Search

Cultivated oil palm is commonly found in several ecosystems with different topographies, including riparian areas. This ecosystem is expected to affect the morphology and physiology of oil palms. In addition, oil palm habitats in riparian or flooded ecosystems will experience anaerobic respiration. Indonesia has the potential to access quality palm oil that can be used for cultivation. This study aimed to determine which oil palm accessions could adapt physiologically to the duration of waterlogging. The accession of oil palm seedlings from Jambi tested were Merangin, Tebo, Muara Jambi, Tanjung Jabung, and Simalungun. The research design was to treat waterlogging in a greenhouse and then analyze the plant growth and physiology. Waterlogging was given for two, four, and six weeks. The results showed that the accession of oil palm seedlings and the duration of waterlogging affected photosynthesis rate, transpiration rate, and stomatal conductance. Growth parameters, i.e., fresh weight, dry weight, and root/shoot ratio, were significantly different in accession and waterlogging duration. In conclusion, accessions from Tebo and Merangin can adapt to waterlogging. [ABSTRACT FROM AUTHOR]

The rise in extreme weather events due to climate change challenges the balance of supply and demand for high-quality agricultural products. In Taiwan, greenhouse cultivation, a key agricultural method, faces increasing summer temperatures and higher operational costs. This study presents the innovative AI-powered greenhouse environmental control system (AI-GECS), which integrates customized gridded weather forecasts, microclimate forecasts, crop physiological indicators, and automated greenhouse operations. This system utilizes a Multi-Model Super Ensemble (MMSE) forecasting framework to generate accurate hourly gridded weather forecasts. Building upon these forecasts, combined with real-time in-greenhouse meteorological data, the AI-GECS employs a hybrid deep learning model, CLSTM-CNN-BP, to project the greenhouse's microclimate on an hourly basis. This predictive capability allows for the assessment of crop physiological indicators within the anticipated microclimate, thereby enabling preemptive adjustments to cooling systems to mitigate adverse conditions. All processes run on a cloud-based platform, automating operations for enhanced environmental control. The AI-GECS was tested in an experimental greenhouse at the Taiwan Agricultural Research Institute, showing strong alignment with greenhouse management needs. This system offers a resource-efficient, labor-saving solution, fusing microclimate forecasts with crop models to support sustainable agriculture. This study represents critical advancements in greenhouse automation, addressing the agricultural challenges of climate variability. [ABSTRACT FROM AUTHOR]

Drought stress affects many aspects of plant biochemistry, with photosynthesis being one the most significantly impaired physiological processes. Melatonin is a natural antioxidant with growth-regulating properties in plants. Its diverse physiological functions have been extensively studied in recent decades. Changes in leaf gas exchange and chlorophyll a fluorescence parameters were investigated in young wheat plants (Triticum aestivum L.) cv. Fermer and cv. Gines which were characterized to differ in their responses to drought, with cv. Gines being more tolerant than cv. Fermer. The plants were subjected to drought for five days by withholding their water supply. Melatonin was applied as a root supplement to the irrigation water before or after the drought period. Analyses were performed before and at the end of the stress period, as well as during the recovery phase. Changes in leaf pigment content, photosynthetic rate, stomatal conductance, and transpiration, as well as some chlorophyll a fluorescence parameters, were recorded. Melatonin alone did not cause considerable changes in the measured traits. We found a significant decrease in leaf gas exchange parameters, Fv/Fm and Fv/F0 values, and leaf pigments due to drought, especially in cv. Fermer. The data show that the application of melatonin favorably influenced the efficiency of the photosynthetic apparatus under water deprivation and during plant recovery. The pre-treatment with melatonin maintained the photosynthesis-related parameters closer to the control levels during the stress period. Both melatonin treatments supported the recovery of photosynthesis when the water supply was restored and the post-drought treatment showed a similar but weaker effect than pre-drought treatment. [ABSTRACT FROM AUTHOR]

The most prevalent light source for different plant species being cultivated under ex situ conditions is fluorescent lighting. Nevertheless, other light sources, such as light-emitting diodes (LEDs) in different colors, have shown to be more effective for such controlled conditions. In the present research, we have assessed the impact of variable light qualities on stevia (Stevia rebaudiana Bert.) seed germination and plant growth inside regulated environmental conditions. For this intent, red (RD), white (WH), blue (BL), and the different combinations of RD and BL LEDs were arranged in the plant factory system (PFS). Interestingly, it was found that the fresh weight (FW) and dry weight (DW) of leaves per plant (10.8 and 1.9 g) and FW and DW of roots per plant (2.7 and 0.4 g) measured to be maximum under RD:BL (1:1) exposure. The plants grown in PFS illuminated with RD:BL (8:2) LEDs showed maximum photosynthesis rate (8 μmol CO2/m2/s), chlorophyll a content (1.1 µg/ml), and stomata length and width in comparison to other LED exposures. Stomatal conductance and transpiration rate recorded maximum at 200 μmol/mol of CO2 concentration in plants raised under RD:BL (1:1) with 275 and 2.3 mmol H2O/m2/s, respectively. RuBisCO activity was recorded to be maximum under WH LED (0.17 µg/g). It was observed that a combination of RD and BL LEDs is more suitable for improved biomass, photosynthesis rate, chlorophyll contents, and stomatal conductance in the PFS than that of other individual light sources. The application of such biomass enhancement approach described in the present work might be advantageous for ameliorated steviol glycosides accumulation in stevia. [ABSTRACT FROM AUTHOR]

Wheat is one of the primary cereals in most countries, and in recent decades, its cultivation has been significantly impacted by environmental conditions due to climate change. Therefore, an experiment was conducted during the 2020-2021 agricultural year to examine the response of photosynthetic pigments and the yield of different wheat cultivars to the combined application of bacteria and sulfur under rainfed conditions. This factorial experiment was conducted in a randomized complete block design with three replications. The experimental factors included four wheat cultivars: Eivan, Sardari, Homa, and Azar 2, sulfur treatment at two levels: foliar spray with distilled water as a control and foliar spray with sulfur and bacterial treatment at two levels: without inoculation (control) and inoculation with Azospirillum bacteria. The results showed that the highest grain yield (3030 kg/ha) was observed in the Eivan cultivar with the application of Azospirillum bacteria. Inoculation with Azospirillum bacteria increased the grain yield of the Eivan and Sardari cultivars by 17.9% and 42%, respectively, while no statistically significant effect was observed on the grain yield of the Homa and Azar 2 cultivars. The results indicated that sulfur spraying and bacterial application improved photosynthesis. Under rainfed conditions, the Eivan cultivar had significantly higher grain yield compared to the Sardari, Homa, and Azar 2 cultivars and produced a higher yield with bacterial application. Azospirillum bacteria increased leaf photosynthesis. Plant nutrition management and the use of growth-promoting bacteria, with their physiological effects, can be considered strategies for improving yield under rainfed conditions. [ABSTRACT FROM AUTHOR]

Introduction: Tropical cloud forest ecosystems are expected to face reduced water inputs due to climatic changes. Methods: Here, we study the ecophysiological responses of trees and epiphytes within in an Asian cloud forest to investigate the contributions of rainfall, fog, and soil to leaf water in 60 tree and 30 vascular epiphyte species. We measured multiple functional traits, and δ² H, and δ18O isotope ratios for leaf water, soil water, rainfall, and fog in the wettest (July) and driest (February) months. Using a Bayesian stable isotope mixing model, we quantified the relative contributions of soil water, fog, and rainfall to leaf water. Results and discussion: Rainfall contributes almost all the leaf water of the epiphytes in July, whereas fog is the major source in February. Epiphytes cannot tap xylem water from host trees, and hence depended on fog water when rainfall was low. Most of leaf water was absorbed from soil water in July, while fog was an important source for leaf water in February despite the soil moisture content value was high. In February, lower temperatures, along with reduced photosynthesis and transpiration rates, likely contributed to decreased soil water uptake, while maintaining higher soil moisture levels despite the limited rainfall. These contrasting contributions of different water sources to leaf water under low and high rainfall and for different plant groups outline the communityl-evel ecophysiological responses to changes in rainfall. While direct measurements of water flux, particularly in roots and stems, are needed, our results provide valuable insights on tropical cloud forest hydrology under scenarios of decreased fog immersion due to climatic changes. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is one of the most important cereal crops in the world. Bakanae disease is a significant rice disease widely distributed in rice-growing regions worldwide. Therefore, the present investigation aimed to assess the optimal concentrations of paclobutrazol (PBZ) as a treatment for rice grains (cv. Sakha 108) to control bakanae disease, also evaluating its impact on grain germination, seedling growth parameters as well as disease index. Paclobutrazol concentrations had no significant impact on seed germination, regardless of whether the seeds were incubated with Fusarium fujikuroi or not. Application of PBZ, either alone or in combination with fungal pathogens, negatively impacted the rice seedlings' height. Paclobutrazol at 25, 50 and 100 mg/L, combined with the fungal pathogen positively impacted root length. Paclobutrazol at 3 and 6 mg/L mitigated the adverse impact on chlorophyll pigments content in infected seedlings. The highest proline contents were achieved by 100 mg/L PBZ alone or in combination with fungal pathogens. It has been observed that the application of PBZ, either alone or in combination with a fungal pathogen, leads to the enhancement of catalase, peroxidase, and polyphenol oxidase activities. The median lethal concentration of PBZ was 0.874 mg/L; applying low concentrations of paclobutrazol effectively increased the percentage of fungal growth suppression. Application of PBZ, at higher concentrations (50 and 100 mg/L), decreased infection percentage and disease severity index (DSI) significantly. These findings suggest that PBZ can be an effective treatment for controlling bakanae disease and enhancing resistance in rice plants. [ABSTRACT FROM AUTHOR]

Introduction: Under water stress conditions, intercropping can be used as a strategy for maximum use of sunlight and limited water resources. Due to the difference in morphological and physiological traits, the two plants corn and mung bean may be suitable for intercropping under drought stress; Therefore, this research was conducted with the aim of investigating the effects of drought stress on the physiological traits and yield of corn and mung beans in monocultures and intercropping in order to study the possibility of reducing water consumption in this production system. Materials and methods: An experiment was carried out as a split plot based on randomized complete block design with three replications at Ilam University during 2019-2020 growing season. The main plot were four water regimes including (40, 60, 80, and 100% of the plant's water requirement) and the subplots were include the planting pattern at four levels (additive intercropping series 100% corn + 50% mung bean, replacement intercropping series 50% corn + 50% mung bean and monocultures of mung bean and corn). The application of drought stress started after the establishment stage of the plant and continued until the harvest. At the end of the growth period, some physiological traits of both plants were measured, including photosynthetic pigments, photosynthesis rate, transpiration rate, intercellular CO2 concentration, proline amount, leaf relative water content and grain yield. Finally, analysis of variance (ANOVA) was performed using Minitab 14 and SAS 9.1 softwares and the means compared by HSD test at 5% probability level (p≤0.05). Results and discussion: The results showed the highest rate of photosynthesis (25.4 µmol CO2.m-2.s-1) was obtained in the treatment of 100% water requirement and the lowest rate of photosynthesis was obtained in 40% water requirement, which showed a decrease of 68.5% compared to the well-watered conditions. The rate of photosynthesis of corn in the replacement intercropping of 50% corn + 50% mung bean was 18.3% higher compared to monocultures corn. The highest rate of mung bean photosynthesis was observed in replacement intercropping under conditions of 100% water requirement and additive intercropping series under 80% water requirement, and the lowest rate of mung bean photosynthesis was observed in intercropping under conditions of 60 and 40% water requirement. Dehydration stress decreased the amount of total chlorophyll in mung beans and corn. The highest intercellular CO2 concentration (475.5 mmol of CO2.m-2.s-1) and the temperature of the corn leaf (36.7 °C) belonged to the 40% water requirement treatment. The rate of transpiration of corn and mung bean decreased by 55.56 and 61.43% in the condition of 40% water requirement compared to well-watered conditions. Water stress reduced the relative water content of corn and mung bean. The highest proline in corn and mung leaves (46.3 and 45.23 µmol.g-1.FW-1, respectively) was obtained in the treatment of 40% water requirement, which had no significant difference with 60% water requirement. Corn grain yield in the treatment of 40% water requirement showed a decrease of 52.76% compared to 100% water requirement. Monocultures (3945.8 kg.ha-1) and intercropping (3875.1 kg.ha-1) had the highest corn grain yield, and the lowest corn grain yield in replacement intercropping was 2700 kg ha-1. At all irrigation levels, the highest grain yield of mung bean was obtained in monocultures, and the yield decreased in additive and replacement intercropping, and additive intercropping had the lowest grain yield. The values of land equality ratio of all intercropping patterns were greater than one, which indicates the advantage of corn and mung bean intercropping patterns to use land and increase yield. Conclusion: Considering the occurrence of recent droughts in arid and semi-arid regions of the country and the need for forage in these regions, the cultivation of forage plants, especially corn, is inevitable. Therefore, one of the appropriate strategies to protection in management and water consumption is the intercropping of this plant with plants of the legume such as mung bean. Intercropping can partially moderate the effects of drought stress on plant water conditions. In general, it seems that the patterns of intercropping and substitution, due to having higher grain yield potential, is a suitable strategy for producing higher yield and stability of this plant compared to monocultural under well-watered and stress water. Acknowledgments: This research has been carried out using the research credits of Ilam University, by which we express our thanks and appreciation to the respected Assistance of Research and Technology of Ilam University. [ABSTRACT FROM AUTHOR]

IntroductionUnder water stress conditions, intercropping can be used as a strategy for maximum use of sunlight and limited water resources. Due to the difference in morphological and physiological traits, the two plants corn and mung bean may be suitable for intercropping under drought stress; Therefore, this research was conducted with the aim of investigating the effects of drought stress on the physiological traits and yield of corn and mung beans in monocultures and intercropping in order to study the possibility of reducing water consumption in this production system.Materials and methodsAn experiment was carried out as a split plot based on randomized complete block design with three replications at Ilam University during 2019-2020 growing season. The main plot were four water regimes including (40, 60, 80, and 100% of the plant's water requirement) and the subplots were include the planting pattern at four levels (additive intercropping series 100% corn + 50% mung bean, replacement intercropping series 50% corn + 50% mung bean and monocultures of mung bean and corn). The application of drought stress started after the establishment stage of the plant and continued until the harvest. At the end of the growth period, some physiological traits of both plants were measured, including photosynthetic pigments, photosynthesis rate, transpiration rate, intercellular CO2 concentration, proline amount, leaf relative water content and grain yield. Finally, analysis of variance (ANOVA) was performed using Minitab 14 and SAS 9.1 softwares and the means compared by HSD test at 5% probability level (p≤0.05).Results and discussionThe results showed the highest rate of photosynthesis (25.4 µmol CO2.m-2.s-1) was obtained in the treatment of 100% water requirement and the lowest rate of photosynthesis was obtained in 40% water requirement, which showed a decrease of 68.5% compared to the well-watered conditions. The rate of photosynthesis of corn in the replacement intercropping of 50% corn + 50% mung bean was 18.3% higher compared to monocultures corn. The highest rate of mung bean photosynthesis was observed in replacement intercropping under conditions of 100% water requirement and additive intercropping series under 80% water requirement, and the lowest rate of mung bean photosynthesis was observed in intercropping under conditions of 60 and 40% water requirement. Dehydration stress decreased the amount of total chlorophyll in mung beans and corn. The highest intercellular CO2 concentration (475.5 mmol of CO2.m-2.s-1) and the temperature of the corn leaf (36.7 °C) belonged to the 40% water requirement treatment. The rate of transpiration of corn and mung bean decreased by 55.56 and 61.43% in the condition of 40% water requirement compared to well-watered conditions. Water stress reduced the relative water content of corn and mung bean. The highest proline in corn and mung leaves (46.3 and 45.23 µmol.g-1.FW-1, respectively) was obtained in the treatment of 40% water requirement, which had no significant difference with 60% water requirement. Corn grain yield in the treatment of 40% water requirement showed a decrease of 52.76% compared to 100% water requirement. Monocultures (3945.8 kg.ha-1) and intercropping (3875.1 kg.ha-1) had the highest corn grain yield, and the lowest corn grain yield in replacement intercropping was 2700 kg ha-1. At all irrigation levels, the highest grain yield of mung bean was obtained in monocultures, and the yield decreased in additive and replacement intercropping, and additive intercropping had the lowest grain yield. The values of land equality ratio of all intercropping patterns were greater than one, which indicates the advantage of corn and mung bean intercropping patterns to use land and increase yield.ConclusionConsidering the occurrence of recent droughts in arid and semi-arid regions of the country and the need for forage in these regions, the cultivation of forage plants, especially corn, is inevitable. Therefore, one of the appropriate strategies to protection in management and water consumption is the intercropping of this plant with plants of the legume such as mung bean. Intercropping can partially moderate the effects of drought stress on plant water conditions. In general, it seems that the patterns of intercropping and substitution, due to having higher grain yield potential, is a suitable strategy for producing higher yield and stability of this plant compared to monocultural under well-watered and stress water.AcknowledgmentsThis research has been carried out using the research credits of Ilam University, by which we express our thanks and appreciation to the respected Assistance of Research and Technology of Ilam University.

Abstract Climate change has become a concern, emphasizing the need for the development of crops tolerant to drought. Therefore, this study is designed to explore the physiological characteristics of quinoa that enable it to thrive under drought and other extreme stress conditions by investigating the combined effects of irrigation water levels (100%, 75%, and 50% of quinoa's water requirements, WR as I1, I2 and I3) and different planting methods (basin, on-ridge, and in-furrow as P1, P2 and P3) on quinoa's physiological traits and gas exchange. Results showed that quinoa’s yield is lowest with on-ridge planting and highest in the in-furrow planting method. Notably, the seed protein concentrations in I2 and I3 did not significantly differ but they were 25% higher than those obtained in I1, which highlighted the possibility of using a more effective irrigation method without compromising the seed quality. On the other hand, protein yield (PY) was lowest in P2 (mean of I1 and I2 as 257 kg ha−1) and highest in P3 (mean of I1 and I2 as 394 kg ha−1 , 53% higher). Interestingly, PY values were not significantly different in I1 and I2, but they were lower significantly in I3 by 28%, 27% and 20% in P1, P2, and P3, respectively. Essential plant characteristics including plant height, stem diameter, and panicle number were 6.1–16.7%, 6.4–24.5%, and 18.4–36.5% lower, respectively, in I2 and I3 than those in I1. The highest Leaf Area Index (LAI) value (5.34) was recorded in the in-furrow planting and I1, while the lowest value was observed in the on-ridge planting method and I3 (3.47). In I3, leaf temperature increased by an average of 2.5–3 oC, particularly during the anthesis stage. The results also showed that at a similar leaf water potential (LWP) higher yield and dry matter were obtained in the in-furrow planting compared to those obtained in the basin and on-ridge planting methods. The highest stomatal conductance (gs) value was observed within the in-furrow planting method and full irrigation (I1P3), while the lowest values were obtained in the on-ridge and 50%WR (I3P2). Finally, photosynthesis rate (An) reduction with diminishing LWP was mild, providing insights into quinoa’s adaptability to drought. In conclusion, considering the thorough evaluation of all the measured parameters, the study suggests using the in-furrow planting method with a 75%WR as the best approach for growing quinoa in arid and semi-arid regions to enhance production and resource efficiency.

Climate change has become a concern, emphasizing the need for the development of crops tolerant to drought. Therefore, this study is designed to explore the physiological characteristics of quinoa that enable it to thrive under drought and other extreme stress conditions by investigating the combined effects of irrigation water levels (100%, 75%, and 50% of quinoa's water requirements, WR as I1, I2 and I3) and different planting methods (basin, on-ridge, and in-furrow as P1, P2 and P3) on quinoa's physiological traits and gas exchange. Results showed that quinoa's yield is lowest with on-ridge planting and highest in the in-furrow planting method. Notably, the seed protein concentrations in I2 and I3 did not significantly differ but they were 25% higher than those obtained in I1, which highlighted the possibility of using a more effective irrigation method without compromising the seed quality. On the other hand, protein yield (PY) was lowest in P2 (mean of I1 and I2 as 257 kg ha−1) and highest in P3 (mean of I1 and I2 as 394 kg ha−1, 53% higher). Interestingly, PY values were not significantly different in I1 and I2, but they were lower significantly in I3 by 28%, 27% and 20% in P1, P2, and P3, respectively. Essential plant characteristics including plant height, stem diameter, and panicle number were 6.1–16.7%, 6.4–24.5%, and 18.4–36.5% lower, respectively, in I2 and I3 than those in I1. The highest Leaf Area Index (LAI) value (5.34) was recorded in the in-furrow planting and I1, while the lowest value was observed in the on-ridge planting method and I3 (3.47). In I3, leaf temperature increased by an average of 2.5–3 oC, particularly during the anthesis stage. The results also showed that at a similar leaf water potential (LWP) higher yield and dry matter were obtained in the in-furrow planting compared to those obtained in the basin and on-ridge planting methods. The highest stomatal conductance (gs) value was observed within the in-furrow planting method and full irrigation (I1P3), while the lowest values were obtained in the on-ridge and 50%WR (I3P2). Finally, photosynthesis rate (An) reduction with diminishing LWP was mild, providing insights into quinoa's adaptability to drought. In conclusion, considering the thorough evaluation of all the measured parameters, the study suggests using the in-furrow planting method with a 75%WR as the best approach for growing quinoa in arid and semi-arid regions to enhance production and resource efficiency. [ABSTRACT FROM AUTHOR]

Zinc (Zn) is an essential micronutrient that participates in several plant metabolisms. Soil application of Zn is an effective strategy to increase the productivity and Zn concentration in maize grains, but the effect of Zn fertilizers on the nutrients uptake and biofortification still needs more studies. In this study, a greenhouse plot experiment was conducted to evaluate the effect of the optimum Zn fertilizer doses (0, 5.7, and 11.4 kg ha−1) on the nutrients uptake and Zn biofortification of maize crops. Zn applications were found to increase significantly the transpiration rate; photosynthesis rate, Zn, and P concentration in the maize shoot at the VT (Tasseling) stage as well as the grain Zn and maize grain yield. P, Mg, and phytic acid (PA) concentration in grains was also increased with a Zn application of 11.4 kg ha−1. The PA/Zn molar ratio in grains decreased due to the Zn application doses as compared with the control treatment, but there was no significant difference between Zn 5.7 and 11.4 kg ha−1 doses, while Zn 5.7 kg ha−1 achieved a higher PA/Fe molar ratio in maize grains compared to other treatments. [ABSTRACT FROM AUTHOR]

Phymatosorus scolopendria, commonly known as monarch fern or wart fern, grows naturally as an epiphyte, lithophyte, or terrestrial plant primarily in the seasonally dry tropical biome, and is widely distributed in Africa, Southeastern Asia, Indonesia, and extending south to northeastern Australia. It has become naturalized in Florida, Bermuda, Hawaii, and localities in South America. Although it is widely distributed geographically, and maintained in cultivation, less is known about its physiological ecology. This is a report of the photosynthesis, respiration, and physiological properties of P. scolopendria grown under controlled laboratory conditions with moderate light intensity of 100 µmol m–2 s–1 and temperature of 25C, approximating semi-shaded environmental conditions. Maximum net photosynthesis rate based on leaf area was 1.50 µmol m–2 s–1, and based on leaf dry weight was 1,581.80 nmol CO2 gdw–1 min–1. Dark respiration rate based on leaf area was 0.24 µmol CO2 m–2 s–1, and per leaf dry weight was 319.54 nmol CO2 gdw min–1. The specific leaf area was 209.52. Mean density of stomata on the abaxial leaf surface was 3,242 cm–2, and leaf stomatal water vapor conductance was c. 62 mmol H2O m–2 s–1. [ABSTRACT FROM AUTHOR]

Introduction: One of the most important problems threatening agriculture is water deficit stress in many regions of the world. Water deficit stress could result in a decrease in yielding or death of a wide range of crops. In Iran, like other arid and semi-arid regions, forage quality and production have decreased due to the occurrence of frequent water stress. Restriction of water resources, especially in arid and semi-arid regions where agricultural systems depend on supplementary irrigation, has become the most important problem of fodder production. Persian clover (Trifolium resupinatum L.) is a forage legume cultivated in the temperate region of world; it is of great value for livestock feed, soil improvement, and reclaiming disturbed land because of its nitrogen-fixing capability. The purpose of this research, was evaluate the effect of water deficit stress on the physiological and qualitative traits of fodder of Persian clover. Materials and methods: An experiment was carried out during the 2016 and 2017 cropping seasons as a randomized complete block design at the Research Farm of Tarbiat Modares University. Experimental treatments included water deficit stress at four levels. The tested treatments included water deficit stress at four levels (irrigation after reaching the levels of 80, 60, 40 and 20% available moisture). Irrigation of all treatments was carried out at the level of 70% of available water until the start of stress in the final stages of vegetative growth of the second cut. To measure the effects of water deficit stress on physiological traits physiological indexes were recorded during the first 10 days of stress treatment, every day. The clovers were harvested at about 20-25% flowering stage. After drying, they were transferred to the laboratory to determine the quantitative and qualitative feed yield. Based on Bartlett's test results, the experiment's dependent variables had the same trend. Results and discussion: The results show that the irrigation regime had a significant effect on all traits. Irrigation treatments at 80 and 60% of available water had the highest dry matter yield, and delaying irrigation until 40 and 20% caused a 19% and 36% significant decrease in this trait. Also, stress at the level of 20% caused a 27% decrease in fodder protein, a 10% increase in acid detergent fiber and neutral detergent fiber, and finally, an 16% reducing relative feed value. Evaluation of physiological traits in the first ten days of the beginning of water stress showed a continuous increase in leaf temperature from 30.5 to 34 °C, and 49, 50, and 15% decrease in photosynthesis rate, stomatal conductance, and SPAD index, respectively. It Also reduces the concentration of chlorophyll a and b 25 and 40 percent. The return of increased leaf temperature and reduced stomatal conductance due to the discharge of 80% moisture was fast to the initial level, but other traits slowly approached the value before the stress. It seems that returning to initial values at levels of 80 and 60 is easily possible for the plant, but with the increase in the intensity of stress, the damage of dehydration is slowly compensated. Conclusion The experiment results showed that the photosynthesis rate and other physiological traits of Persian clover significantly react to the soil's decreased available water. In most physiological traits, irrigation after the available soil moisture reached 60% caused a relatively quick return to the initial value. There was no significant difference in fodder yield in the 80% and 60% irrigation treatments. When the available soil moisture reached 40%, the physiological traits showed a greater decrease than before. It seems that some damages to physiological traits are irreparable to such an extent that they eventually lead to a drop in yield or a decrease in the quality of Persian clover fodder. Finally, it is not necessary for clover irrigation at levels of more than 60% of available water, taking into account the more quality of forage in the level of 60% (about 1.5% of insoluble fiber, and 11% feed value), considering the water conditions of the country. [ABSTRACT FROM AUTHOR]

Abtract: Climate change; the most concerning issue throughout the globe, is now considered a major cause of heat stress which is deteriorating agricultural crops. A pot experiment was performed to examine the ameliorative role of melatonin foliar spray on growth attributes, physiological attributes and yield and quality attributes of heat-tolerant and heat-sensitive genotypes of tomatoes under heat stress mediated by field environment. The results demonstrated that all the growth parameters of all tomato genotypes such as plant fresh biomass, plant dry biomass, stem girth, leaf area, the number of viable seeds, protein contents as well as physiological attributes including photosynthetic rate, stomatal contents, transpiration rate, chlorophyll contents, water use efficiency (WUE) and synthesis of osmoprotectants including proline and glycine betain (GB) were increased significantly upon foliar application of melatonin @ 25 µM under heat stress except electrolyte leakage (EL), leaf temperature and hydrogen peroxide contents (H2O2) which were decreased in all cultivars of tomato either in heat tolerant or in heat sensitive; as compared to their respective control which remained untreated. Similarly, acivity of enzymatic and non-enzymatic antioxidants including nitric oxide synthase (NOS), glutathione reductase (GR), nitrate reductase (NR) and glutathione S transferase (GST) were also improved upon melatonin foliar application under heat stress. However, the maximum improvement in all measured attributes was observed in all types of tomato genotypes grown under both control and 25 µM melatonine foliar spray treatment. All these findings proved that melatonin spray is capable to address the deteriorative impact of high temperature on tomato growth.

Abstract Yerba mate (Ilex paraguariensis St. Hil., Aquifoliaceae), a dioecious, subtropical, perennial tree found in South America, was hypothesized to exhibit secondary sexual dimorphism in relation to stomatal density (SD). The objective of this study was to examine the variability of SD in yerba mate leaves and its relationship to secondary sexual dimorphism as a first step towards identifying a genetic marker for gender determination in seedlings. Leaves from four male and four female plants were collected from two monoculture plantations, San Vicente and General Alvear, in the Misiones province, Argentina, during both flowering and vegetative latency periods. Results showed that SD was significantly higher in leaves from female than in male plants in both sites. Also, samples collected during the vegetative growth period have higher SD compared to flowering period. The findings indicate that the SD of yerba mate leaves varies based on gender and serves as a secondary marker for sexual determination in this species. We also discussed the impact of SD variability in photosynthesis rate between female and males.

Drought stress is one of the most important factors that reduce the yield of crops in arid and semi-arid regions, including the climatic conditions of Iran. The experiment was conducted as factorial based on completely randomized design with three replications in the research greenhouse of Ilam University in 2020. The experimental factors included irrigation at three levels (100, 60, and 30% of field capacity) and three accessions of camelina (Kermanshah, Sabzevar, and Shahrekord). The results showed that under the irrigation conditions of 30%, seed yield, biological yield, harvest index, plant height, number of capsules per plant, number of seeds per capsule, relative leaf water content, photosynthesis rate, transpiration rate, stomatal conductance and total chlorophyll respectively 69.4, 53.8, 33.9, 44.1, 72.9, 25.6, 43.8, 72.0, 62.9, 56.7, and 61.1% reduction compared to optimal irrigation they found There was no difference observed between the three populations investigated in different irrigation conditions in terms of the investigated traits. In addition, the results showed that the highest amount of camellia seed oil (39%) was obtained in Kermanshah massif under favorable irrigation conditions; which decreased by 40.8% under severe stress of dehydration. In general, it is possible to use camelina Kermanshah under conditions of moderate water stress for oil production. [ABSTRACT FROM AUTHOR]

IntroductionDust storms are meteorological phenomena that usually occur in arid and semi-arid regions with an annual rainfall of less than 200 to 250 mm when strong winds blow with a high speed. Dust particles affect plants growth and development directly by depositing in shoot or indirectly by changing soil chemical properties (Maletsika et al., 2015). The interference of weeds with the mungbean (Vigna radiate) plant is one of the important factors limiting the production capacity of this crop, which leads to a decrease in yield and an increase in production costs. The competition between crops and weeds becomes more complicated when coincide with environmental stresses like soil dust. Compared to crops, weeds are more resistant to environmental stresses and have a high capacity to absorb more water and nutrients. The aim of this research was to evaluate the competitive balance between lambsquarters and mungbean under soil dust conditions in order to manage production of this crop with lambsquarters under soil dust conditions. Materials and MethodsThe pot experiment was carried out in the research greenhouse of the Faculty of Agriculture of Ilam University, Iran in spring of 2022. The experiment was conducted as a factorial based on a completely randomized design with four replications. The treatments were included soil dust at two levels (0 and 60 g dust.m-3 of air) and replacement planting pattern at five levels (mungbean monoculture, lambsquarters monoculture, alternative intercropping of 75% mungbean + 25% lambsquarters, 50% mungbean + 50% lambsquarters and 25% mungbean + 75% lambsquarters). Totally, four plants per pots were sown. The measured traits were included physiological characteristics such as photosynthetic pigments, photosynthesis rate, transpiration rate, leaf area, plant height, stem diameter, biological yield and grain yield components of mungbean and inflorescence yield of lambsquarters. Results and DiscussionThe results showed that soil dust has no significant effect on the morpho-physiological characteristics of lambsquarters weed, while it decreased the photosynthesis rate, leaf relative water content, leaf area, plant height, number of pods per plant, biological yield and grain yield of mungbean by 26.1, 9.7, 10.6, 19.3, 14.8, 24 and 23.2%, respectively. The highest amount of chlorophyll in mungbean leaves (4.65 mg g-1 fresh weight of leaves) was obtained in the intercropping patterns of 75% mungbean + 25% lambsquarters and monoculture of mungbean under no dust conditions. The highest photosynthesis rate, transpiration rate, leaf area and number of pods in mungbean plant were observed in monoculture and planting pattern of 75% mungbean + 25% lambsquarters. The highest seeds number per plant (10.4 and 10.1) was observed in monoculture of mungbean and planting pattern of 75% mungbean + 25% lambsquarters under the no dust condition, which was 30.5 and 65.8 percent higher compared to dust treatment, respectively. The lowest seed number per plant (3.3) was obtained in 25% mungbean + 75% lambsquarters. Under both dust and no dust conditions in all plant patterns, the actual mungbean seed yield was lower than the expected yield and the changes in curve of mungbean yield was concave; but the actual yield of lambsquarters was more than the expected lambsquarters inflorescence yield, and the curve was convex suggesting a commensalism relationship for lambsquarters and amensalism relationship for mungbean. The relative crowding coefficient and the competition ratio under both conditions of dust and in different planting patterns were obtained for lambsquarters weed, were greater than one, which indicates the superiority of lambsquarters competitive ability compared to mungbean. The aggressivity index of lambsquarters under dusty conditions was higher than under dust-free conditions, which shows that lambsquarters weed has more competitive capacity under environmental stress conditions including soil dust. The results also showed that the mungbean plant has a greater potential to absorb dust than the lambsquarters weed, which is due to the presence of trichome in mungbean leaves surface. In general, in this experiment the lambsquarters dominated the mungbean plant in competition for water and nutritional resources and had better growth compared to mungbean in different planting patterns. ConclusionIn the presence of dust, lambsquarters weed may have higher efficiency to use environmental resources due to its higher adaptability compared to the mungbean and causes decreasing in the yield of crop plants including mungbean. The interactive effect of dust and the interference from lambsquarters caused a significant decrease in mungbean yield. Therefore, the management of lambsquarters under dusty conditions is of important value.

Drought stress affects many aspects of plant biochemistry, with photosynthesis being one the most significantly impaired physiological processes. Melatonin is a natural antioxidant with growth-regulating properties in plants. Its diverse physiological functions have been extensively studied in recent decades. Changes in leaf gas exchange and chlorophyll a fluorescence parameters were investigated in young wheat plants (Triticum aestivum L.) cv. Fermer and cv. Gines which were characterized to differ in their responses to drought, with cv. Gines being more tolerant than cv. Fermer. The plants were subjected to drought for five days by withholding their water supply. Melatonin was applied as a root supplement to the irrigation water before or after the drought period. Analyses were performed before and at the end of the stress period, as well as during the recovery phase. Changes in leaf pigment content, photosynthetic rate, stomatal conductance, and transpiration, as well as some chlorophyll a fluorescence parameters, were recorded. Melatonin alone did not cause considerable changes in the measured traits. We found a significant decrease in leaf gas exchange parameters, Fv/Fm and Fv/F0 values, and leaf pigments due to drought, especially in cv. Fermer. The data show that the application of melatonin favorably influenced the efficiency of the photosynthetic apparatus under water deprivation and during plant recovery. The pre-treatment with melatonin maintained the photosynthesis-related parameters closer to the control levels during the stress period. Both melatonin treatments supported the recovery of photosynthesis when the water supply was restored and the post-drought treatment showed a similar but weaker effect than pre-drought treatment.

Tillage practices have been widely acknowledged to play a critical role in optimizing water use efficiency (WUE) for winter wheat production in the Northern China Plain (NCP) where drought is a critical limiting factor. Therefore, the WUE of wheat as influenced by annual rotational tillage under the corn–wheat cropping system during 2016–2018 has determined. The tillage regimes in the corn season were either N: no–tillage or SR: sub–soiling with rotary tillage). One of three regimes, sTR: strip rotary tillage; R: rotary tillage; and SR: sub–soiling with rotary tillage) were the tillage practices in the wheat seasons. Thus, making a total of 6 treatments. N–SR markedly decreased the penetration resistance, while the soil water storage was enhanced in the 60-100 cm layer during the wheat season, over both years. On the other hand, the use of SR during the wheat-growing season increased evapotranspiration. Compared with other tillage practices, the photosynthesis rate enhanced under the N–SR. As a result, the highest yield and WUE of wheat were recorded in the N–SR regime. Our findings suggest that no–tillage in the corn season and sub–soiling with rotary tillage in the succeeding wheat season can improve wheat yield by promoting deep soil water, enhancing the leaves photosynthesis rate and increasing WUE.

IntroductionMortality of the riparian alder population caused by Phytophthora pathogens has been studied for over 20 years throughout Europe, recently gaining more importance in the context of evident climate change. The main objective of this study was to examine the pathogenicity of species from the “Phytophthora alni complex” present in the Czech Republic (P. × alni and P. uniformis) and P. plurivora to Alnus glutinosa seedlings grown at ambient and elevated CO2 concentration.MethodsAn underbark inoculation test was performed with seedlings grown from seeds collected from two Czech alder populations, one suffering from severe Phytophthora decline and the other disease-free.ResultsThe results showed significant differences in lesion development and seedling mortality. After a 13-week experimental period, at both CO2 levels P. × alni and P. uniformis showed high aggressiveness to A. glutinosa seedlings causing lesions of variable sizes and mortality of 33.3%, and 45.8% of plants, respectively. In contrast, P. plurivora did not cause mortality to any plant, and lesion sizes did not differ significantly from those in control plants. Physiological measurements did not reveal any significant differences between Phytophthora species except for plants inoculated with P. plurivora showing increased values in specific physiological parameters 4 weeks post-inoculation. Net photosynthesis decreased over the measurement period in all treatments with significant differences found between measurements conducted 2 and 4 weeks after the inoculation. Transpiration showed a decreasing trend in all inoculated plants with no significant differences between Phytophthora species at both CO2 levels. Chemical analyses of root samples showed high variability in sugars and phenolic compounds related to the plant's health status.DiscussionThis is the first study to examine the response of alder seedlings to Phytophthora pathogens at different CO2 levels. The findings demonstrate high aggressiveness of P. × alni and P. uniformis and weaker aggressiveness of P. plurivora to alder seedlings regardless of the CO2 level.

Evaluating the impacts of high temperature-mediated changes in soil-plant systems is crucial in sustaining the productivity of heat-sensitive crops like chickpea (Cicer arietinum L.). Currently, the impact of a high temperature environment on soil processes and crop nutrition, particularly phosphorus (P), remains uncertain in tropical alkaline soils. Therefore, an open-top chamber-based experiment with ambient temperature [a(Temp)] and elevated temperature [e(Temp)] (+2 °C over ambient) aimed to investigate the impacts of high temperature environment on plant physiology, soilplant P dynamics, and yield of chickpea in a moderately-alkaline Vertisol of sub-tropical climate. The e(Temp) reduced Olsen-P (available-P) and NaHCO3-Pi at the flowering stage by 12% and 32%, respectively, as compared to a(Temp) treatment. The e(Temp) treatment markedly reduced KMnO4-oxidizable carbon (-25% to 42%), but did not alter water-soluble carbon. Alkaline phosphatase and ß-glucosidase activities were reduced under the e(Temp) treatment, while acid phosphatase activity remained unchanged. The elevated temperature had a significant impact on chlorophyll-b content (+18%), stomatal conductance (+5%), transpiration rate (+8%), and photosynthetic rate (-22%). The e(Temp) treatment did not alter total P uptake rather altered its distribution in grain (-16%) and stover (+17%) parts, resulting in a lower internal P use efficiency (-12%) and P harvest index (+15%). The e(Temp) treatment caused 12% yield loss compared to a(Temp) treatment. Therefore, this is concluded that retardation in P-mineralization along with terminal heat stress could impair P nutrition, physiological activity, and yield of chickpea. [ABSTRACT FROM AUTHOR]

Tillage practices have been widely acknowledged to play a critical role in optimizing water use efficiency (WUE) for winter wheat production in the Northern China Plain (NCP) where drought is a critical limiting factor. Therefore, the WUE of wheat as influenced by annual rotational tillage under the corn-wheat cropping system during 2016-2018 has determined. The tillage regimes in the corn season were either N: no-tillage or SR: sub-soiling with rotary tillage). One of three regimes, sTR: strip rotary tillage; R: rotary tillage; and SR: sub-soiling with rotary tillage) were the tillage practices in the wheat seasons. Thus, making a total of 6 treatments. N-SR markedly decreased the penetration resistance, while the soil water storage was enhanced in the 60-100 cm layer during the wheat season, over both years. On the other hand, the use of SR during the wheat-growing season increased evapotranspiration. Compared with other tillage practices, the photosynthesis rate enhanced under the N-SR. As a result, the highest yield and WUE of wheat were recorded in the N-SR regime. Our findings suggest that no-tillage in the corn season and sub-soiling with rotary tillage in the succeeding wheat season can improve wheat yield by promoting deep soil water, enhancing the leaves photosynthesis rate and increasing WUE. [ABSTRACT FROM AUTHOR]

IntroductionCovering a staggering 215 million hectares, wheat stands as the world's most extensively cultivated crop plant. Just like its botanical counterparts, wheat operates as an obligate aerobic organism, implying its reliance on absorbing oxygen from the surrounding environment to facilitate growth, proliferation, and the successful completion of its life cycle. Annual instances of waterlogging stress inflict harm upon wheat crops, attributed to inadequate irrigation practices, subpar drainage systems, uneven field leveling, elevated groundwater levels, the presence of unyielding impermeable layers, and bouts of intense, abrupt rainfall. This adverse impact is progressively escalating, potentially influenced by the ongoing shifts in climate patterns. Consequently, the adoption of resilient cultivars and the genetic enhancement of bread wheat assume critical importance. These strategies are aimed at augmenting the wheat's capacity to effectively cope with waterlogging stress, aligning it with the mounting demands of a burgeoning global population.To achieve these goals, it is necessary to understand the factors causing waterlogging stress damage in wheat and to know the mechanisms of tolerance in this plant. The survival of root terminal meristem cells under waterlogging stress conditions is very limited, and their ability to grow again after removing the stress is also restricted. Waterlogging stress leads to the death of primary roots and reduced growth of lateral roots in wheat. However, there is variation among wheat cultivars concerning these traits. Reduced access to oxygen hampers root growth and nutrient absorption, including nitrogen. Consequently, photosynthesis and carbohydrate availability decrease, further restricting root growth.Materials and MethodsAn outdoor pot experiment was conducted to investigate the effect of waterlogging stress on shoot and root dry matter, as well as some physiological characteristics. The experiment followed a split-plot design based on randomized complete blocks with three replications. The stress was applied at the three-leaf stage, and three control levels were used: no waterlogging stress, mild stress (48 hours of waterlogging stress), and severe stress (120 hours of waterlogging stress) as the main factors. Cultivars and genotypes were also included as secondary factors.During the stress period, the water level was maintained at approximately 5 cm above the soil level. The cultivation took place outdoors in plastic pots. Data analysis was performed using SAS software, and graphs were generated using Excel software. Comparisons between treatments were based on the standard error. After testing different models, the linear regression model was ultimately employed.Results and DiscussionMild and severe waterlogging stress resulted in a significant decrease in shoot dry matter of 14.06% and 38.37%, respectively, across all cultivars and genotypes. Different cultivars and genotypes exhibited varying responses to waterlogging stress. To further understand the reasons for these differences, among the 21 cultivars and genotypes, Mehrgan and Sarang cultivars, as well as ms 93-16 and ms 93-6 genotypes, were selected due to their contrasting tolerance levels and yield potential. These selected cultivars and genotypes were studied to analyze specific root traits.Amidst severe waterlogging stress, a significant 38% reduction in root dry matter and a corresponding 29% decrease in root volume were recorded when compared to stress-free conditions. This closely mirrored the decline evident in shoot dry matter. Evaluation of the susceptibility index during the three-leaf stage unveiled that sole resilience was exhibited by the Aflak cultivar. In contrast, the remaining cultivars and genotypes were stratified into semi-tolerant and semi-susceptible categories.Notably, regression analysis underscored that even brief periods of waterlogging stress ushered in a reduction in dry matter. Furthermore, the elongation of the waterlogging duration magnified this decrease in dry matter, thereby mitigating the disparities across various cultivars and genotypes.ConclusionIn general, cultivars that were able to sustain higher levels of photosynthetic activity during waterlogging stress demonstrated a lower percentage decrease in dry matter. Although the Mehrgan cultivar experienced a significant reduction in dry matter yield and fell into the semi-sensitive group, it consistently exhibited significantly higher dry matter yield compared to other cultivars and genotypes across all treatments.AcknowledgmentThe authors express their gratitude to the Agriculture Research Center of Khuzestan for providing the seeds, the Research Vice-Chancellor of the Shahid Chamran University of Ahvaz for covering the costs, and all the employees of the Department of Plant Production and Genetics.

Toona ciliata M. Roem. is a valuable and fast-growing timber species which is found in subtropical regions; however, drought severely affects its growth and physiology. Although the exogenous application of salicylic acid (SA) has been proven to enhance plant drought tolerance by regulating the osmotic system and photosynthesis rate, the physiological processes involved in the regulation of drought tolerance by SA in various plants differ. Therefore, drought mitigation techniques tailored for T. ciliata should be explored or developed for the sustainable development of the timber industry. We selected 2-year-old T. ciliata seedlings for a potting experiment, set the soil moisture at 45%, and subjected some of the T. ciliata seedlings to a moderate drought (MD) treatment; to others, 0.5 mmol/L exogenous SA (MD + SA) was applied as a mitigation test, and we also conducted a control using a normal water supply at 70% soil moisture (CK). Our aim was to investigate the mitigating effects of exogenous SA on the growth condition, osmotic system, and photosynthesis rate of T. ciliata under drought stress conditions. OPLS–VIP was used to analyze the main physiological factors that enable exogenous SA to alleviate drought-induced injury in T. ciliata. The results indicated that exogenous SA application increased the growth of the ground diameter, plant height, and leaf blades and enhanced the drought tolerance of the T. ciliata seedlings by maintaining the balance of their osmotic systems, improving their gas exchange parameters, and restoring the activity of their PSII reaction centers. The seven major physiological factors that enabled exogenous SA to mitigate drought-induced injury in the T. ciliata seedlings were the soluble proteins (Sp), net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), stomatal opening window (Sow), activity of the photosystem II reaction center (ΦPSII), and electron transfer rate (ETR). Of these, Sp was the most dominant factor. There was a synergistic effect between the osmotic system and the photosynthetic regulation of drought injury in the T. ciliata seedlings. Overall, our study confirms that exogenous SA enhances the drought tolerance of T. ciliata by modulating the osmotic system and photosynthesis rate. [ABSTRACT FROM AUTHOR]

Introduction Dust storms are meteorological phenomena that usually occur in arid and semi-arid regions with an annual rainfall of less than 200 to 250 mm when strong winds blow with a high speed. Dust particles affect plants growth and development directly by depositing in shoot or indirectly by changing soil chemical properties (Maletsika et al., 2015). The interference of weeds with the mungbean (Vigna radiate) plant is one of the important factors limiting the production capacity of this crop, which leads to a decrease in yield and an increase in production costs. The competition between crops and weeds becomes more complicated when coincide with environmental stresses like soil dust. Compared to crops, weeds are more resistant to environmental stresses and have a high capacity to absorb more water and nutrients. The aim of this research was to evaluate the competitive balance between lambsquarters and mungbean under soil dust conditions in order to manage production of this crop with lambsquarters under soil dust conditions. Materials and Methods The pot experiment was carried out in the research greenhouse of the Faculty of Agriculture of Ilam University, Iran in spring of 2022. The experiment was conducted as a factorial based on a completely randomized design with four replications. The treatments were included soil dust at two levels (0 and 60 g dust.m-3 of air) and replacement planting pattern at five levels (mungbean monoculture, lambsquarters monoculture, alternative intercropping of 75% mungbean + 25% lambsquarters, 50% mungbean + 50% lambsquarters and 25% mungbean + 75% lambsquarters). Totally, four plants per pots were sown. The measured traits were included physiological characteristics such as photosynthetic pigments, photosynthesis rate, transpiration rate, leaf area, plant height, stem diameter, biological yield and grain yield components of mungbean and inflorescence yield of lambsquarters. Results and Discussion The results showed that soil dust has no significant effect on the morpho-physiological characteristics of lambsquarters weed, while it decreased the photosynthesis rate, leaf relative water content, leaf area, plant height, number of pods per plant, biological yield and grain yield of mungbean by 26.1, 9.7, 10.6, 19.3, 14.8, 24 and 23.2%, respectively. The highest amount of chlorophyll in mungbean leaves (4.65 mg g-1 fresh weight of leaves) was obtained in the intercropping patterns of 75% mungbean + 25% lambsquarters and monoculture of mungbean under no dust conditions. The highest photosynthesis rate, transpiration rate, leaf area and number of pods in mungbean plant were observed in monoculture and planting pattern of 75% mungbean + 25% lambsquarters. The highest seeds number per plant (10.4 and 10.1) was observed in monoculture of mungbean and planting pattern of 75% mungbean + 25% lambsquarters under the no dust condition, which was 30.5 and 65.8 percent higher compared to dust treatment, respectively. The lowest seed number per plant (3.3) was obtained in 25% mungbean + 75% lambsquarters. Under both dust and no dust conditions in all plant patterns, the actual mungbean seed yield was lower than the expected yield and the changes in curve of mungbean yield was concave; but the actual yield of lambsquarters was more than the expected lambsquarters inflorescence yield, and the curve was convex suggesting a commensalism relationship for lambsquarters and amensalism relationship for mungbean. The relative crowding coefficient and the competition ratio under both conditions of dust and in different planting patterns were obtained for lambsquarters weed, were greater than one, which indicates the superiority of lambsquarters competitive ability compared to mungbean. The aggressivity index of lambsquarters under dusty conditions was higher than under dust-free conditions, which shows that lambsquarters weed has more competitive capacity under environmental stress conditions including soil dust. The results also showed that the mungbean plant has a greater potential to absorb dust than the lambsquarters weed, which is due to the presence of trichome in mungbean leaves surface. In general, in this experiment the lambsquarters dominated the mungbean plant in competition for water and nutritional resources and had better growth compared to mungbean in different planting patterns. Conclusion In the presence of dust, lambsquarters weed may have higher efficiency to use environmental resources due to its higher adaptability compared to the mungbean and causes decreasing in the yield of crop plants including mungbean. The interactive effect of dust and the interference from lambsquarters caused a significant decrease in mungbean yield. Therefore, the management of lambsquarters under dusty conditions is of important value. [ABSTRACT FROM AUTHOR]

In response to increasing global warming, extreme heat stress significantly alters photosynthetic production. While numerous studies have investigated the temperature effects on photosynthesis, factors like vapour pressure deficit (VPD), leaf nitrogen, and feedback of sink limitation during and after extreme heat stress remain underexplored. This study assessed photosynthesis calculations in seven rice growth models using observed maximum photosynthetic rate (Pmax) during and after short‐term extreme heat stress in multi‐year environment‐controlled experiments. Biochemical models (FvCB‐type) outperformed light response curve‐based models (LRC‐type) when incorporating observed leaf nitrogen, photosynthetically active radiation, temperatures, and intercellular CO2 concentration (Ci) as inputs. Prediction uncertainty during heat stress treatment primarily resulted from variation in temperatures and Ci. Improving FVPD (the slope for the linear effect of VPD on Ci/Ca) to be temperature‐dependent, rather than constant as in original models, significantly improved Ci prediction accuracy under heat stress. Leaf nitrogen response functions led to model variation in leaf photosynthesis predictions after heat stress, which was mitigated by calibrated nitrogen response functions based on active photosynthetic nitrogen. Additionally, accounting for observed differences in carbohydrate accumulation between panicles and stems during grain filling improved the feedback of sink limitation, reducing Ci overestimation under heat stress treatments. Summary statement: The predictions of rice leaf photosynthesis during and after heat stress were improved by modifying the effects of temperature, VPD, nitrogen, and feedback of sink limitation, based on multi‐model comparison approach. [ABSTRACT FROM AUTHOR]

Studies on fertilization management of species native to the Amazon for energy plantations contribute to the diversity of species use and reduce biological risk due to the excessive use of clones or hybrids of Eucalyptus. This study evaluates the effect of precipitation seasonality and phosphorus and potassium fertilization on gas exchange in a Tachigali vulgaris plantation. Three levels of P (zero, 65.2, 130.4 kg ha−1) and three of K (zero, 100.0, 200.0 kg ha−1) were applied in a 3 × 3 factorial randomized block design. Gas exchange measurements were conducted in April and November 2018. In low rainfall, high irradiance period, photosynthetic rates were up to four times higher than in the high rainfall period, reaching 20.3 μmol m−2 s−1 in the treatment with 130.4 g kg−1 of P and 100.0 g kg−1 of K. Factor analysis and principal component analysis reduced the initial eight gas exchange variables to two and three principal components in periods of high and low rainfall, respectively. The multivariate method used in this study readily identified variations in the variables as a function of rainfall, with high reliability in explaining the data set. [ABSTRACT FROM AUTHOR]

Water availability and nitrogen (N) supply are two major issues that affect plant productivity, however, the processes of water and N utilization and their hormone regulation are not conclusive in response to varying water-N interaction. The objective of this study was to evaluate the effects of water stress (WS) at different growth stages on maize plant development, root morphology, water utilization, hormone signaling and N accumulation under various N conditions. A set of controlled drought stress at 60% field capacity was conducted from bell (V12) to tassel (VT) stage (V12-VT, denoted as W1W2), from silk (R1) to milk (R3) stage (R1-R3, denoted as W2W1) and their compound stages (V12-R3, denoted as W1W1) under high- and low-N supply, respectively. The results indicated that compared to the well-watered control (W2W2), W2W1 reduced root length, root area, and shoot dry matter by 4.68–19.15%, 5.92–11.97% and 4.38–29.61%, respectively, while W1W2 promoted the root system and improved the shoot growth, grain formation and plant water use efficiency (WUEp). High N supply tended to aggravate WS with a poorer root system and lower leaf water potential (ψleaf) but higher leaf abscisic acid (ABA) accumulation at different growth stages. Leaf ABA significantly increased while stomatal conductance (Gs) decreased under WS and N-rich environment, hence increasing leaf intrinsic water use efficiency (WUEi). Root zeatin-riboside (ZR) was higher for well-watered and N-rich conditions. Moreover, leaf ABA significantly increased with the decrease of ψleaf (R2 =0.51 for R3, R2 =0.35 for dough stage (R4)) and the variation of ψleaf was relatively constant (≤0.3 MPa) with different water treatments, indicating that maize performed isohydric behavior to response water stress and N-rich environment. This study suggests that to promote the potential of water- and N-saving and improve crop productivity in maize cultivation, mild water stress at vegetative growth stages and appropriate N supply are of great importance.

Night temperature plays a key role in the growth and development of rice plants, specifically the flowering and grain filling stages. An increase in night temperature more than the normal range is regarded as high night temperature (HNT). The HNT results in reduced yield; largely the action mechanism of HNT induced rice grain yield loss remains unknown. The present study provides a comprehensive and holistic analysis of HNT induced impact on several morphological, physiological and anatomical factors which individually or in combination may be linked with yield loss. Normal night temperature (AMB) and + 2° C and + 5° C increase (referred to as HNTs) from ambient temperature was imposed on seven rice varieties viz. Ronga Ahu, Haringa, Inglonkiri, Dishang, Maibee, and Banglami over 2 years in bioreactor facilities. The Nagina-22 (N-22), a drought tolerant variety was used as a reference line. Based on grain yield and grain filling percentage, Maibee was highly sensitive; while Bangalami was the most tolerant to HNT. Key parameters of reproductive growth were reduced by HNT among all the varieties, with Bangalami and Maibee proving tolerant and sensitive to HNT. Among the physiological attributes viz. Fv/Fm, NPQ, qP, Pn, gs, iCO2, ETR, and Φ yield showed deviation from normal values under HNT, which led to a reduction in carboxylation efficiency and carbohydrate synthesis in all the varieties. Leaf anatomical features negatively impacted by HNT included the size of the stomatal pore, xylem, and phloem profiles. The SPAD showed a linear correlation with a reduction in leaf chlorophyll, and leaf and grain nitrogen content under HNT. Structured equation modeling (SEM) estimated the contribution of all the morphological and physiological variables toward grain yield loss under HNT. Among the 27 variables, mainly carboxylation efficiency (CO_S), quantum yield (QY_S), dark respiration (RES_S), Fv/Fm (FVFM_S), and non-photochemical and photochemical quenching (NPQ/PQ_S), chlorophyll stability (CS_S) were able to explain variance in grain yield loss under HNT in Bangalami, Maibee, and N-22. The findings of the present study provided a novel insight into the HNT action mechanism responsible for a reduction in growth, development, and yield in rice. Furthermore, SEM indicates important attributes which were crucial for HNT induced yield loss in rice varieties under study. [ABSTRACT FROM AUTHOR]

Greenhouse gas (GHG) emissions from anthropogenic activities are the most significant drivers of climate change, which has both direct and indirect effects on crop production. The study was conducted during the kharif season for two years inside the Open Top Chamber (OTC) at the Genetic-H field of ICAR-Indian Agriculture Research Institute (IARI) to quantify the effect of elevated CO2 and temperature on water use efficiency of two rice varieties viz. Pusa Basmati 1509 and Nagina 22. There were two different CO2 concentrations i.e. ambient (410 ppm) and elevated (550 ± 25 ppm) and also two of rice different temperature levels i.e. ambient and elevated (+2.5-2.9°C). Results suggested that warming caused more accumulated GDD in rice, which negatively affected the duration of both the varieties. In elevated CO2 plus high temperature interaction, net photosynthesis rate was more than that of control while stomatal conductance and transpiration rate got reduced. Hence the study showed that, co-elevation of CO2 and temperature improved WUE (both instantaneous and intrinsic), of the crop. [ABSTRACT FROM AUTHOR]

Analysis of ecological and evolutionary aspects leading to durability of resistance in soybean cultivars against species Soybean vein necrosis orthotospovirus (SVNV) (Bunyavirales: Tospoviridae) is important for the establishment of integrated pest management (IPM) across the United States, which is a leading exporter of soybeans in the world. SVNV is a seed- and thrips- (vector)-borne plant virus known from the USA and Canada to Egypt. We monitored the resistance of soybean cultivars against SVNV, surveyed thrips species on various crops including soybeans in Pennsylvania, and studied thrips overwintering hibernation behavior under field conditions. Field and lab experiments determined disease incidence and vector abundance in soybean genotypes. The impact of the virus, vector, and their combination on soybean physiology was also evaluated. Seed protein, fiber, oil, and carbohydrate content were analyzed using near infra-red spectroscopy. We found that the variety Channel3917R2x had higher numbers of thrips; hence, it was categorized as preferred, while results showed that no variety was immune to SVNV. We found that thrips infestation alone or in combination with SVNV infection negatively impacted soybean growth and physiological processes. [ABSTRACT FROM AUTHOR]

Wheat stripe rust, due to infection by Puccinia striiformis f. sp. tritici (Pst), is a devastating disease that causes significant global grain yield losses. Yr36, which encodes Wheat Kinase START1 (WKS1), is an effective high-temperature adult-plant resistance gene and confers resistance to a broad spectrum of Pst races. We previously showed that WKS1 phosphorylates the thylakoid ascorbate peroxidase protein and reduces its ability to detoxify peroxides, which may contribute to the accumulation of reactive oxygen species (ROS). WKS1-mediated Pst resistance is accompanied by leaf chlorosis in Pst-infected regions, but the underlying mechanisms remain elusive. Here, we show that WKS1 interacts with and phosphorylates PsbO, an extrinsic member of photosystem II (PSII), to reduce photosynthesis, regulate leaf chlorosis, and confer Pst resistance. A point mutation in PsbO-A1 or reduction in its transcript levels by RNA interference resulted in chlorosis and reduced Pst sporulation. Biochemical analyses revealed that WKS1 phosphorylates PsbO at two conserved amino acids involved in physical interactions with PSII and reduces the binding affinity of PsbO with PSII. Presumably, phosphorylated PsbO proteins dissociate from the PSII complex and then undergo rapid degradation by cysteine and aspartic proteases. Taken together, these results demonstrate that perturbations of wheat PsbO by point mutation or phosphorylation by WKS1 reduce the rate of photosynthesis and delay the growth of Pst pathogen before the induction of ROS.

A greenhouse experiment was conducted to examine the influence of Phelipanche aegyptiaca on vegetative growth, rate of photosynthesis, chlorophyll fluorescence and leaf chlorophyll content of 35 cucumber genotypes. High demand of assimilates by P. aegyptiaca caused significant reductions in shoot and root dry weight, leaf number, leaf area and plant height in all cucumber genotypes. Once plants were infected by P. aegyptiaca, the leaf chlorophyll content, the photosynthesis rate and the maximum quantum yield of PSII chemistry were significantly less than control, thus implying a reduction in carbon assimilation, photosynthesis efficiency and susceptibility of infected plants to photoinhibition. P. aegyptiaca traits were significantly affected by cucumber genotypes. There was no correlation between P. aegyptiaca traits with the reduction percentage of cucumber shoot dry weight. However, there were correlations between underground attachments number plant-1 (UAN) and percentage of cucumber root dry weight reduction (-0.58), total attachment number plant -1 (TAN) and the percentage of reduction of root dry weight (+0.39). In accordance with the results obtained, the genotypes were classified into 3 groups. It was demonstrated that the genotype number 22 (Khassib) behaved differently to other genotypes and, in particular, they suffered less damage from the presence of P. aegyptiaca.

Greenhouse gas (GHG) emissions from anthropogenic activities are the most significant drivers of climate change, which has both direct and indirect effects on crop production. The study was conducted during the kharif season for two years inside the Open Top Chamber (OTC) at the Genetic-H field of ICAR-Indian Agriculture Research Institute (IARI) to quantify the effect of elevated CO2 and temperature on water use efficiency of rice varieties. There were two different CO2 concentrations i.e. ambient (410 ppm) and elevated (550 ± 25 ppm) and also two different temperature levels i.e. ambient and elevated (+2.5-2.9°C). Results suggested that warming caused more accumulated GDD in rice and which negatively affected the duration of both the varieties. In elevated CO2 plus high temperature interaction treatment net photosynthesis rate was more than that of chamber control. Stomatal conductance and transpiration rate reduced with co-elevation of CO2 and temperature. Co-elevation of CO2 and temperature, has also improved WUE (both instantaneous and intrinsic) through enhanced carbon assimilation and reduced stomatal conductance, thus, reducing the amount of water lost through transpiration, eventually improving WUE of the crop.

The aim of this study was to examine how light intensity and quality affect the photosynthetic apparatus of Cyanidioschyzon merolae cells by modulating the structure and function of phycobilisomes. Cells were grown in equal amounts of white, blue, red, and yellow light of low (LL) and high (HL) intensity. Biochemical characterization, fluorescence emission, and oxygen exchange were used to investigate selected cellular physiological parameters. It was found that the allophycocyanin content was sensitive only to light intensity, whereas the phycocynin content was also sensitive to light quality. Furthermore, the concentration of the PSI core protein was not affected by the intensity or quality of the growth light, but the concentration of the PSII core D1 protein was. Finally, the amount of ATP and ADP was lower in HL than LL. In our opinion, both light intensity and quality are main factors that play an important regulatory role in acclimatization/adaptation of C. merolae to environmental changes, and this is achieved by balancing the amounts of thylakoid membrane and phycobilisome proteins, the energy level, and the photosynthetic and respiratory activity. This understanding contributes to the development of a mix of cultivation techniques and genetic changes for a future large-scale synthesis of desirable biomolecules. [ABSTRACT FROM AUTHOR]

The physiological mechanisms of shade tolerance and trait plasticity variations under shade remain poorly understood in rice (Oryza sativa L.). Twenty-five genotypes of rice were evaluated under open and shade conditions. Various parameters to identify variations in the plasticity of these traits in growth irradiance were measured. We found wide variations in specific leaf weight (SLW) and net assimilation rate measured at 400 µmol m−2 s−1 photosynthetic photon flux density (PPFD; referred to as A 400) among the genotypes. Under shade, tolerant genotypes maintained a high rate of net photosynthesis by limiting specific leaf weight accompanied by increased intercellular CO2 concentration (C i) compared with open-grown plants. On average, net photosynthesis was enhanced by 20% under shade, with a range of 2–30%. Increased accumulation of biomass under shade was observed, but it showed no correlation with photosynthetic plasticity. Chlorophyll a / b ratio also showed no association with photosynthetic rate and yield. Analysis of variance showed that 11%, 16%, and 37% of the total variance of A 400, SLW, and C i were explained due to differences in growth irradiance. SLW and A 400 plasticity in growth irradiance was associated with yield loss alleviation with R 2 values of 0.37 and 0.16, respectively. Biomass accumulation was associated with yield loss alleviation under shade, but no correlation was observed between A 400 and leaf-N concentration. Thus, limiting specific leaf weight accompanied by increased C i rather than leaf nitrogen concentration might have allowed rice genotypes to maintain a high net photosynthesis rate per unit leaf area and high yield under shade. Plasticity in photosynthesis and specific leaf weight (SLW) are traits that allow shade-tolerant rice (Oryza sativa L.) genotypes to alleviate yield loss under shade. This was achieved by a reduction in SLW with increased intercellular CO2 concentration (C i). Leaf nitrogen did not influence photosynthesis rate under shade, but an accumulation of biomass was associated with yield. Limiting SLW with increased C i is the principal strategy to alleviate loss in photosynthesis and yield under low light intensity. [ABSTRACT FROM AUTHOR]

Plants subjected to mechanical stimulation respond by undergoing morphological changes (thigmomorphogenesis). Wind is an environmental factor that induces mechanical stimulation of plants, affecting their growth and photosynthetic responses depending on its speed. In this study, we evaluated the effects of wind stimulation on watermelon seedlings in terms of wind speed, stimulation time, and application timing. We found that wind stimulation decreases the growth of watermelon seedlings, mainly suppressing their height. Among different wind treatments, the dwarf rate was the highest in the treatment performed at a wind speed of 4 m‧s−1 for 10 h per day. Compactness was the highest in the control treatment with diniconazole, and it increased with increasing exposure to different wind treatments. Low wind speeds, such as 1 m‧s−1, increased the photosynthesis rate and water-use efficiency of the exposed seedlings; however, wind speed of 4 m‧s−1 decreased the photosynthesis rate. Moreover, wind stimulation increased transpiration in watermelon seedlings. Among different plug seedling production stages, wind application after the grafting stage resulted in effective growth retardation of watermelon seedlings. After transplanting, wind stimulation at the plug seedling stage did not have a negative effect on watermelon growth. Thus, wind stimulation can be used as a potential growth retardant for suppressing plant height in watermelon seedlings. [ABSTRACT FROM AUTHOR]

Milk thistle Silybum marianum (L.) Gaertn. is one of the most researched medicinal plants, but at the same time it belongs to crops with wide industry potential whose growth requirements for marginal agroecological conditions or the response to agronomic interventions has not yet been sufficiently studied. The aim of the present research was to verify the effect of mineral nutrition (NPK 200 kg/ha) and humic acids applied to the soil (HUMAC Agro 250 kg/ha) on the main biometric parameters and the intensity of photosynthesis of milk thistle grown under less favourable climatic conditions of the semi-cold and humid foothills in Central Europe. The highest seed yield was achieved with the NPK variant in terms of dry matter 0.534 t/ha, in the HUMAC Agro variant 0.254 t/ha and with the untreated control 0.087 t/ha. The soil before the trial establishment was characterised by low nutrient content. The use of mineral fertiliser on NPK treatment eliminated the influence of low PK nutrients content of the soil, influencing the crop growth and yield/quality, while no doses of NPK were used on the HUMAC Agro variant and the untreated control. For both of the two sequences created (temperature and light), the highest photosynthesis rate was measured on untreated control (20.115 and 12.386 mmol/m2/s1), markedly lower on HUMAC Agro (16.386 and 9.653 mmol/m2/s1) – and the lowest on the NPK (10.933 and 7.813 mmol/m2/s1, respectively), in inverse proportion to the crop yield. Therefore, the size of the leaf area of the crop was decisive for the increased crop yield. The polynomial trend line of the photosynthesis rate according to the temperature sequence shows the photosynthesis rate and the torrential decrease by temperature increasing on untreated control compared with both treated variants. Both of these threats, mineral nutrition and use of humic preparations to soil, although they reduce the photosynthesis rate, have a wide range of complex effects that provide an opportunity to optimise the growth and yield of milk thistle. Ideally, the mineral nutrition and humic preparations should be used in combination with the crop of milk thistle for medicinal and energy purposes.

Drought is the most predominant abiotic factor that affects plant growth and development. The present research examined how drought stress affected the growth, physiological, and biochemical responses of Local and Markofana red pepper (Capsicum annum L.) cultivars. Five-week-old cultivars were exposed to well-watered, low, moderate, and severe drought conditions and kept at 100, 80, 60 and 40 % of field capacity, respectively. Nine-week-old cultivars were sampled to analyze the effects of the stress on different parameters of both cultivars. Compared with the control group, drought stress caused a reduction in growth, physiological and biochemical parameters; nevertheless, negative effects of the stress were more noticeable in the Local cultivar. Severe drought stress significantly reduced shoot length in Markofana (53.71 %) compared to the control group. Significant variation was observed in relative water content in the Local cultivar (20.26 %) exposed to drought. In the Local cultivar, the total chlorophyll content and chlorophyll fluorescence declined significantly by 77.28 % and 3.33 %, respectively. Therefore, the cultivar Markofana was relatively less affected by drought stress. In general, these differences in cultivar responses to drought stress may aid in developing drought tolerance genotypes that can withstand drought stress conditions with minimal yield losses. [ABSTRACT FROM AUTHOR]

Greenhouse climate control systems are usually based on greenhouse microclimate settings to exert any control. However, to save energy, water and nutrients, additional parameters related to crop performance and physiology will have to be considered. In addition, detecting crop stress before it is clearly visible by naked eye is an advantage that could aid in microclimate control. In this study, a Machine Learning (ML) model which takes into account microclimate and crop physiological data to detect different types of crop stress was developed and tested. For this purpose, a multi-sensor platform was used to record tomato plant physiological characteristics under different fertigation and air temperature conditions. The innovation of the current model lies in the integration of photosynthesis rate (Ps) values estimated by means of remote sensing using a photochemical reflectance index (PRI). Through this process, the time-series Ps data were combined with crop leaf temperature and microclimate data by means of the ML model. Two different algorithms were evaluated: Gradient Boosting (GB) and MultiLayer perceptron (MLP). Two runs with different structures took place for each algorithm. In RUN 1, there were more feature inputs than the outputs to build a model with high predictive accuracy. However, in order to simplify the process and develop a user-friendly approach, a second, different run was carried out. Thus, in RUN 2, the inputs were fewer than the outputs, and that is why the performance of the model in this case was lower than in the case of RUN 1. Particularly, MLP showed 91% and 83% accuracy in the training sample, and 89% and 82% in testing sample, for RUNs 1 and 2, respectively. GB showed 100% accuracy in the training sample for both runs, and 91% and 83% in testing sample in RUN 1 and RUN 2, respectively. To improve the accuracy of RUN 2, a larger database is required. Both models, however, could easily be incorporated into existing greenhouse climate monitoring and control systems, replacing human experience in detecting greenhouse crop stress conditions. [ABSTRACT FROM AUTHOR]

Toona ciliata M. Roem. is a valuable and fast-growing timber species which is found in subtropical regions; however, drought severely affects its growth and physiology. Although the exogenous application of salicylic acid (SA) has been proven to enhance plant drought tolerance by regulating the osmotic system and photosynthesis rate, the physiological processes involved in the regulation of drought tolerance by SA in various plants differ. Therefore, drought mitigation techniques tailored for T. ciliata should be explored or developed for the sustainable development of the timber industry. We selected 2-year-old T. ciliata seedlings for a potting experiment, set the soil moisture at 45%, and subjected some of the T. ciliata seedlings to a moderate drought (MD) treatment; to others, 0.5 mmol/L exogenous SA (MD + SA) was applied as a mitigation test, and we also conducted a control using a normal water supply at 70% soil moisture (CK). Our aim was to investigate the mitigating effects of exogenous SA on the growth condition, osmotic system, and photosynthesis rate of T. ciliata under drought stress conditions. OPLS–VIP was used to analyze the main physiological factors that enable exogenous SA to alleviate drought-induced injury in T. ciliata. The results indicated that exogenous SA application increased the growth of the ground diameter, plant height, and leaf blades and enhanced the drought tolerance of the T. ciliata seedlings by maintaining the balance of their osmotic systems, improving their gas exchange parameters, and restoring the activity of their PSII reaction centers. The seven major physiological factors that enabled exogenous SA to mitigate drought-induced injury in the T. ciliata seedlings were the soluble proteins (Sp), net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), stomatal opening window (Sow), activity of the photosystem II reaction center (ΦPSII), and electron transfer rate (ETR). Of these, Sp was the most dominant factor. There was a synergistic effect between the osmotic system and the photosynthetic regulation of drought injury in the T. ciliata seedlings. Overall, our study confirms that exogenous SA enhances the drought tolerance of T. ciliata by modulating the osmotic system and photosynthesis rate.

Lycaste aromatica (Graham) Lindl. orchid is known for its outstanding cinnamon aroma, which has caused its illegal and accelerated extraction from its natural habitat. For this reason, procedures were developed for asymbiotic seed germination and seedling development in a gravity immersion bioreactor (GIB) system. Four culture media were tested for in vitro germination: ½ Murashige and Skoog (MS) containing 15 g L−1 sucrose, MS, ½ Knudson C containing 15 g L−1 sucrose, and Knudson C. The efficiency of in vitro culture protocol using semi-solid medium was compared to four immersion frequencies of the GIB system in a liquid medium using 30 mL of ½ MS medium per seedling. Germination began at 8 wk and lasted for 6 wk. The best treatment was ½ MS with 81% seed germination. In 90 d, the GIB did not result in significant effects on most growth parameters, including number of leaves; number of roots and seedling height were not significantly different to those of seedlings developed in the semi-solid medium. However, seedlings developed in the semi-solid medium reported a higher number of shoots (1.6 shoots) and root length (2 cm). The GIB showed the highest photosynthesis rate (0.74 μmol CO2 g−1 s−1). The GIB could be an alternative to develop this species due to its increased photosynthesis and having stomatal function. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Slovenica is the property of Biotechnical Faculty of the University of Ljubljana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Intercropping is an agricultural practice that can improve crop yield due to better availability of resources, including water. There are few studies, however, addressing the physiological mechanisms behind this phenomenon. In this work oilseed rape (Brassica napus L.) and barley (Hordeum vulgare L.) were cultivated either as monocrop (MC) or intercrop (IC) under well-watered (WW) or drought stress (DS) conditions in a growth chamber. After eight weeks DS, the leaf relative water content was higher in the IC compared with the MC plants in both species and the DS-induced senescence of old leaves was considerably postponed in oilseed rape. Intercropped oilseed rape showed elevated levels of leaf photosynthesis rate, superior accumulation of organic osmolytes but higher water loss compared with the MC counterparts under DS conditions. In barley, less transpiration, an increased root : shoot ratio and osmolyte accumulation was observed in the IC compared with MC plants under DS conditions. The water use efficiency was higher in the IC compared to MC barley and the plants yield was higher in the IC than in the MC oilseed rape. Our data showed that intercropping is a reliable practice for cultivation of both species under arid and semi-arid regions or under rainfed conditions.

Climate change; the most concerning issue throughout the globe, is now considered a major cause of heat stress which is deteriorating agricultural crops. A pot experiment was performed to examine the ameliorative role of melatonin foliar spray on growth attributes, physiological attributes and yield and quality attributes of heat-tolerant and heat-sensitive genotypes of tomatoes under heat stress mediated by field environment. The results demonstrated that all the growth parameters of all tomato genotypes such as plant fresh biomass, plant dry biomass, stem girth, leaf area, the number of viable seeds, protein contents as well as physiological attributes including photosynthetic rate, stomatal contents, transpiration rate, chlorophyll contents, water use efficiency (WUE) and synthesis of osmoprotectants including proline and glycine betain (GB) were increased significantly upon foliar application of melatonin @ 25 µM under heat stress except electrolyte leakage (EL), leaf temperature and hydrogen peroxide contents (H 2 O 2) which were decreased in all cultivars of tomato either in heat tolerant or in heat sensitive; as compared to their respective control which remained untreated. Similarly, acivity of enzymatic and non-enzymatic antioxidants including nitric oxide synthase (NOS), glutathione reductase (GR), nitrate reductase (NR) and glutathione S transferase (GST) were also improved upon melatonin foliar application under heat stress. However, the maximum improvement in all measured attributes was observed in all types of tomato genotypes grown under both control and 25 µM melatonine foliar spray treatment. All these findings proved that melatonin spray is capable to address the deteriorative impact of high temperature on tomato growth. [ABSTRACT FROM AUTHOR]

Effects of potassium fertigation on the productivity of Kinnow were investigated in potassium rich soils of South-Western Punjab, India during 2018–2020. Three application rates of potassium i.e. 1000, 750 and 500 g Muriate of Potash (MoP; 60% K as K2O) per tree were applied at fortnightly intervals in two, three and four splits during February, May, July and September. The results were compared with standard recommendation for the region (three foliar sprays of 1% potassium nitrate) and no K application (control). The experiment was laid out in randomized block design, replicated thrice. The data showed that K fertigation significantly (p <.05) improved the growth, yield and quality of fruits over both standard recommendation and control. A comparison among different K split applications (fertigation) revealed higher growth, yield and quality of fruits in trees which received MoP in four splits. However, the differences among 1000 g, 750 g and 500 g K application rates were statistically comparable especially in terms of tree vigor, yield, percent juice, TSS–acid ratio and ascorbic acid content of fruits. These results suggest the fertigation of 500 g MoP per tree in four split applications to achieve higher growth and productivity of Kinnow in K rich soils of South-Western Punjab. [ABSTRACT FROM AUTHOR]

Liquidambar formosana is an excellent landscape ecological tree species because its leaves turn red gradually after autumn, which is of great ornamental value. In this paper, the changes of tissue structures, photosynthetic characteristics and pigment contents of L. formosana leaves were continuously monitored, and the relationships between leaf structures and photosynthetic characteristics and pigment were analyzed in order to understand the relationships between leaf structure changes and leaf color. The results were as follows:(1)During the discoloration process of L. formosana leaves, the epidermal cells were oval and closely arranged, no obvious cell variation was observed, no villi and wax were attached to the surface, and the upper epidermal cells were closely arranged with palisade tissue cells, there was no large air chamber.(2)With the leaf turning red gradually, the leaf structure changed significantly. The thickness of leaf, upper epidermis, palisade tissue, spongy tissue and stomatal aperture decreased gradually, whereas the length and width of stomatal apparatus and the area of single stomatal apparatus gradually increased.(3)With the change of leaf structure, the chlorophyll content decreased gradually, resulting in the decrease of net photosynthetic rate. When light damage occurred, leaves protected themselves by synthesizing anthocyanins in the vacuoles of palisade tissue cells, then a large amount of anthocyanins caused the leaf surface to show red. Therefore, the decrease of chlorophyll content and the accumulation of anthocyanins were the direct reasons for the redness of L. formosana leaves. To sum up, the red color of L. formosana leaves is the combination result of a series of physiological structure characteristics. [ABSTRACT FROM AUTHOR]