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In saline conditions, establishing healthy seedlings is crucial for the productivity of sunflowers (Helianthus annuus L.). Excessive potassium (K+) from irrigation water or overfertilization, similar to sodium (Na+), could adversely affect sunflower growth. However, the effects of salt stress caused by varying K/Na ratios on the establishment of sunflower seedlings have not been widely studied. We conducted a pot experiment in a greenhouse, altering the K/Na ratio of a soil solution to grow sunflower seedlings. We tested three saline solutions with K/Na ratios of 0:1 (P0S1), 1:1 (P1S1), and 1:0 (P1S0) at a constant concentration of 4 dS m−1, along with a control (CK, no salt added), with five replicates. The solutions were applied to the pots via capillary rise through small holes at the bottom. The results indicate that different K/Na ratios significantly influenced ion-selective uptake and transport in crop organs. With an increasing K/Na ratio, the K+ concentration in the roots, stems, and leaves increased, while the Na+ concentration decreased in the roots and stems, with no significant differences in the leaves. Furthermore, an excessive K/Na ratio (P1S0) suppressed the absorption and transportation of Mg2+, significantly reducing the Mg2+ concentration in the stems and leaves. A lower leaf Mg2+ concentration reduced chlorophyll concentration, impairing photosynthetic performance. The lowest plant height, leaf area, dry matter, and shoot/root ratio were observed in P1S0, with reductions of 27%, 48%, 48%, and 13% compared to CK, respectively. Compared with CK, light use efficiency and CO2 use efficiency in P1S0 were significantly reduced by 13% and 10%, respectively, while water use efficiency was significantly increased by 9%. Additionally, improved crop morphological and photosynthetic performance was observed in P1S1 and P0S1 compared with P1S0. These findings underscore the critical role of optimizing ion composition in soil solutions, especially during the sensitive seedling stage, to enhance photosynthesis and ultimately to improve the plant's establishment. We recommend that agricultural practices in saline regions incorporate tailored irrigation and fertilization strategies that prioritize optimal K/Na ratios to maximize crop performance and sustainability. [ABSTRACT FROM AUTHOR]

[Objective] This study aims to explore the effects of exogenous CaCl2 on the growth and photosynthetic characteristics of marigold (Tagetes erecta L.) under saline-alkali stress, and to provide theoretical support for the application of CaCl2 to improve the cultivation efficiency and product quality of marigold on saline-alkali land. [Methods] Taking marigold seedlings as test materials, pot experiment was carried out to observe the growth phenotype, photosynthetic pigment content, photosynthetic gas exchange parameters, and chlorophyll fluorescence parameters of marigold seedlings by watering (CK1), root irrigation with 80 mmol/L mixed saline-alkali solution (CK2), and root irrigation with saline-alkali followed by foliar spraying with four concentrations of CaCl2 solution (5, 10, 15, 20 mmol/L]. [Results] With the prolongation of saline-alkali stress, the plant height, stem diameter, root configuration, and root-shoot ratio of marigold plants showed a gradual upward trend, and the net photosynthetic rate (Pn), transpiration coefficient (Tr), stomatal conductance (Gs), total chlorophyll content (Chl t), and maximum photochemical efficiency (Fv/Fm ) of leaves showed a downward trend, while intercellular CO2 concentration (Ci) showed an upward trend. After spraying different concentrations of CaCl2 on the leaves, the change of each index was decreased. There was a concentration effect, and the effect of 10 mmol/L CaCl2 treatment was the best. On the 20 th day of stress, the Chl t, Pn, Tr, Gs, and Fv/Fm of leaves treated with 10 mmol/L CaCl2 were higher than those of CK2 by 46.78%, 45.53%, 49.51%, 49.57%, and 32.83%, while the root-shoot ratio and Ci were reduced by 22.60% and 30.91%, respectively. [Conclusion] Spraying 10 mmol/L CaCl2 on the leaves reduces the decrease of chlorophyll contents in marigold leaves under saline-alkali stress, increases the electron transport rate of PSⅡ, enhances the photosynthetic capacity of leaves, and effectively improves the growth of plants.

Abstract Nickel (Ni) and copper (Cu) contamination have become major threats to plant survival worldwide. 24-epibrassinolide (24-EBR) and melatonin (MT) have emerged as valuable treatments to alleviate heavy metal-induced phytotoxicity. However, plants have not fully demonstrated the potential mechanisms by which these two hormones act under Ni and Cu stress. Herein, this study investigated the impact of individual and combined application of 24-EBR and MT on the growth and physiological traits of Primula forbesii Franch. subjected to stress (200 μmol L–1 Ni and Cu). The experiments compared the effects of different mitigation treatments on heavy metal (HM) stress and the scientific basis and practical reference for using these exogenous substances to improve HM resistance of P. forbesii in polluted environments. Nickel and Cu stress significantly hindered leaf photosynthesis and nutrient uptake, reducing plant growth and gas exchange. However, 24-EBR, MT, and 24-EBR + MT treatments alleviated the growth inhibition caused by Ni and Cu stress, improved the growth indexes of P. forbesii, and increased the gas exchange parameters. Exogenous MT effectively alleviated Ni stress, and 24-EBR + MT significantly alleviated the toxic effects of Cu stress. Unlike HM stress, MT and 24-EBR + MT activated the antioxidant enzyme activity (by increasing superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)), significantly reduced reactive oxygen species (ROS) accumulation, and regulated ascorbate and glutathione cycle (AsA-GSH) efficiency. Besides, the treatments enhanced the ability of P. forbesii to accumulate HMs, shielding plants from harm. These findings conclusively illustrate the capability of 24-EBR and MT to significantly bolster the tolerance of P. forbesii to Ni and Cu stress.

o uncover the regulatory metabolism of poly-glutamic acid (PGA) in protecting wheat crops against salt stress (SS) at the physiological level, we utilised hydroponic experiments to explore the roles of PGA in regulating the photosynthetic performance, water physiology, antioxidant metabolism and ion homeostasis of wheat seedlings exposed to SS for 10 days. The findings demonstrated that SS inhibited the photosynthetic performance of wheat seedlings. In contrast, different doses of PGA all improved the photosynthetic performance, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS decreased nonphotochemical quenching (qN) by 26.3% and respectively increased photosynthetic rate (Pn), soil and plant analyser development (SPAD) value, maximum photochemical efficiency of photosystem II (PSII) (Fv/Fm), photochemical quenching (qP) and actual photochemical efficiency of PSII (Y(II)) by 54.0, 27.8, 34.6, 42.4 and 25.8%. For water metabolism, SS destroyed the water balance of wheat seedlings. In contrast, different doses of PGA enhanced water balance, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS decreased leaf water saturation deficit (LWSD) by 35.5% and respectively increased leaf relative water content (LRWC), transpiration rate (Tr), stomatal conductance (gs) and the contents of soluble sugars (SSS) and proline (Pro) by 15.9, 94.7, 37.5, 44.6 and 62.3%. For antioxidant metabolism, SS induced the peroxide damage to wheat seedlings. In contrast, different doses of PGA all mitigated the SS-induced peroxide damage, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS respectively decreased superoxide anion (O2-), hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents and electrolyte leakage (EL) by 39.1, 29.6, 46.2 and 36.3%, and respectively increased superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), dehydroascorbate reductases (DHAR) and monodehydroascorbate reductase (MDHAR) activities, and antioxidants ascorbic acid (AsA) and glutathione (GSH) contents by 69.2, 49.2, 77.8, 80.6, 109.5, 121.7, 104.5, 63.8 and 39.6%. Besides, SS destroyed the ion homeostasis of wheat seedlings. In contrast, different doses of PGA all maintained ion homeostasis, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS reduced Na+ content by 40.7% and respectively increased K+, Ca2+ and Mg2+ contents by 64.4, 82.6 and 105.6%, thereby respectively increasing K+/Na+, Ca2+/Na+ and Mg2+/Na+ ratios by 177.6, 209.4 and 244.8%. In the above ways, SS inhibited wheat height and biomass. In contrast, different doses of PGA all improved wheat height and biomass under SS, especially for 0.3% PGA. Compared with SS, 0.3% PGA plus SS, respectively, increased wheat height and biomass by 27.4% and 41.7%. In the above ways, PGA mitigated salt toxicity in wheat seedlings. The current findings implied that there was a potential for the use of PGA in real situations to improve wheat salt tolerance, especially for the 0.3% dose.

Nickel (Ni) and copper (Cu) contamination have become major threats to plant survival worldwide. 24-epibrassinolide (24-EBR) and melatonin (MT) have emerged as valuable treatments to alleviate heavy metal-induced phytotoxicity. However, plants have not fully demonstrated the potential mechanisms by which these two hormones act under Ni and Cu stress. Herein, this study investigated the impact of individual and combined application of 24-EBR and MT on the growth and physiological traits of Primula forbesii Franch. subjected to stress (200 μmol L–1 Ni and Cu). The experiments compared the effects of different mitigation treatments on heavy metal (HM) stress and the scientific basis and practical reference for using these exogenous substances to improve HM resistance of P. forbesii in polluted environments. Nickel and Cu stress significantly hindered leaf photosynthesis and nutrient uptake, reducing plant growth and gas exchange. However, 24-EBR, MT, and 24-EBR + MT treatments alleviated the growth inhibition caused by Ni and Cu stress, improved the growth indexes of P. forbesii, and increased the gas exchange parameters. Exogenous MT effectively alleviated Ni stress, and 24-EBR + MT significantly alleviated the toxic effects of Cu stress. Unlike HM stress, MT and 24-EBR + MT activated the antioxidant enzyme activity (by increasing superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)), significantly reduced reactive oxygen species (ROS) accumulation, and regulated ascorbate and glutathione cycle (AsA-GSH) efficiency. Besides, the treatments enhanced the ability of P. forbesii to accumulate HMs, shielding plants from harm. These findings conclusively illustrate the capability of 24-EBR and MT to significantly bolster the tolerance of P. forbesii to Ni and Cu stress. [ABSTRACT FROM AUTHOR]

Field mulching and deficit irrigation are applied more frequently in the North China Plain for higher water use efficiency. In order to explore the physiological response of winter wheat to mulching materials under different irrigation amounts, a field experiment with three mulching (no mulching, NM; transparent film mulching, TFM; and straw mulching, SM) and two drip irrigation (full and deficit irrigation, FI and DI) treatments were set up. Soil water content, leaf gas exchange parameters, leaf abscisic acid content, and stomatal morphological parameters were measured. The results showed that the soil water content of TFM and SM treatments were higher than that of NM treatment by 12.4%–29.8% and 6.1%–7.1% under FI, respectively. Because of the lower value and larger differences among treatments of soil water content at the filling stage treatment effects on gas exchange parameters were significant. Comparing to NM treatment under FI, the stomatal conductance of TFM and SM treatments under FI increased by 95.9% and 97.9%, respectively; however, the gas exchange parameters of TFM and SM treatments under DI had significantly different responses. In a manner that the net photosynthetic rate and stomatal conductance of TFM treatment increased by 21.7% and 71.7%, while that of SM treatment decreased by 27.2% and 36.1%. Those changes of the gas exchange parameters were accompanied with the change of stomatal morphological parameters and ABA. Line correlations were found between stomatal conductance and leaf abscisic acid content, net photosynthetic rate, and the stomatal perimeter. To sum up, the changes in leaf abscisic acid content and stomatal morphological characteristics mediated the responses of leaf gas exchange parameters to different treatments. The results also suggested that if one needs to reduce the irrigation amounts, transparent plastic film mulching instead of straw mulching should be applied to compensate for the drawback of the lower soil water content. [ABSTRACT FROM AUTHOR]

Rodents, such as those that feed on plants and nest in plant roots, can significantly affect the growth and development of desert plants. The aim of this study was to investigate the effects of Rhombomys opimus disturbance on the photosynthetic characteristics and nutrient status of Haloxylon ammodendron at different growth stages in the Gurbantunggut Desert. The effects of great gerbil disturbance on the photosynthetic characteristics of H. ammodendron at different growth stages were investigated by measuring the gas exchange parameters, instantaneous water use efficiency, and chlorophyll fluorescence parameters of H. ammodendron at different ages (young, middle, and adult) under the disturbance of great gerbils. The soil nutrients in the assimilated branches and rhizosphere of H. ammodendron at different growth stages were tracked to reveal the relationship between the H. ammodendron nutrient content and gerbil disturbance. The results showed that great gerbil disturbance decreased the organic carbon content in the rhizosphere soil of adult H. ammodendron and increased the total nitrogen content in the rhizosphere soil and the nitrogen and potassium contents in the assimilated branches at each growth stage. The net photosynthetic rate and instantaneous water use efficiency of H. ammodendron decreased at each growth stage, and the maximum photochemical efficiency and non-photochemical quenching parameters of the young H. ammodendron decreased. However, the actual photochemical efficiency and photochemical parameters of the middle H. ammodendron increased. It was concluded that the disturbance of great gerbils decreased the photosynthetic capacity of H. ammodendron and increased the content of total nitrogen in the soil and nitrogen and potassium in the plant. This study revealed that the Gurbantunggut Desert great gerbil and H. ammodendron do not have a simple predation relationship. It laid a foundation for the study of the moderate disturbance threshold and better use of the mutually beneficial relationship between the two. [ABSTRACT FROM AUTHOR]

Seedling survival is vital for ecological restoration and carbon neutrality on the Loess Plateau, yet large-scale afforestation in North China has reduced soil water availability in arid and semi-arid areas, complicating efforts to sustain young trees. The water consumption strategies of commonly planted trees and their eco-hydrological responses to varying water conditions remain unclear. Two common tree seedlings, Robinia pseudoacacia and Pinus tabuliformis, were cultivated using soil column experiments to simulate the initial stage of afforestation. Six irrigation treatments (in 100, 200, 300, 400, 500 and 600 mm) were applied to investigate the effect of rainfall recharge on tree physiological traits and water consumptions from June to August in 2021–2022. Results indicated that the both species experienced reduced leaf gas exchange under drought (500 mm), and it was decreased when the vapour pressure deficit >2 kPa. R. pseudoacacia exhibited lower stomatal conductance and transpiration but higher leaf water use efficiency than P. tabuliformis under drought, indicating better drought resilience. The daily evapotranspiration (ET) of the two species was both limited by soil moisture when irrigation 300 mm. A precipitation threshold of 300 mm was identified as critical for seedling growth. Moreover, the mean ET of R. pseudoacacia and P. tabuliformis was 190.43–648.40 and 196.30–620.40 mm, respectively, in the 100–600 mm irrigation treatments during June to August in 2021–2022, and the mean water use efficiency of P. tabuliformis was 55.1 % higher than that of R. pseudoacacia at the plant level. This study will provide critical insights into water consumption strategies to water stress on early afforestation, offering guidance for species selection and ecological restoration on the Loess Plateau.

Abstract [Objective] The heat tolerance of Camellia attracts more attention due to its rich flower types and colors and long flowering period. Suitable evaluation methods and indexes can provide bases for the heat-tolerance identification, the discovery of heat-tolerance germplasm, and the breeding of new cultivars of Camellia. [Methods] C. uraku and ‘Wirlinga Cascade’ were used as reference materials, and 7 new cultivars of cluster-flowering camellia were selected as test materials. They were cut in vase. After shortterm (5 h) or long-term (7 d) high-temperature (42 ℃/35 ℃) treatment, changes of morphological and photosynthetic indexes were investigated and heat tolerance was evaluated comprehensively. [Results] (1) The contents of chlorophyll, carotenoid, and chlorophyll a/b, net photosynthetic rate (Pn), and stomatal conductance (Gs) of ‘Chuizhi Fenyu’ and ‘Wirlinga Cascade’ were increased. Their maximum photochemical efficiency of PSⅡ (Fv/Fm ), potential activity of PSⅡ (Fv/Fo), and electron transport rate (ETR) were remained at a high level. Additionally, they did not show signs of heat damage after 7 days of high temperatures. Pn and Gs of ‘Jinye Fenyu’, ‘Shangzhi Huazhang’, and ‘Meigui Chun’ were decreased significantly under high temperature stress, while intercellular CO2 concentration (Ci) was increased. Among them, the Fv/Fm, Fv/Fo, and ETR of ‘Jinye Fenyu’ and ‘Shangzhi Huazhang’ were significantly reduced. After 7 days of long-term high temperature stress, these 3 cultivars showed severe heat damage or became dead. (2) 15 individual indicators were converted into 4 independent comprehensive indicators with cumulative contribution rate of 90% through principal component analysis. The comprehensive weight values of chlorophyll content, carotenoid content, and xanthophyll content were higher at 5 h under high temperature stress, and the comprehensive weight values of chlorophyll a/b, Fv/Fm, photochemical quenching coefficient (qP), and non-photochemical quenching coefficient (qN) were higher at 7 d under high temperature stress. [Conclusion] According to the comprehensive evaluation value D , ‘Chuizhi Fenyu’ is a heat-tolerance cultivar, ‘Shangzhi Yueguangqu’, ‘Shangzhi Huanlesong’, and ‘Sweet Gem’ are moderate tolerance, and ‘Meigui Chun’, ‘Shangzhi Huazhang’, and ‘Jinye Fenyu’ are the weakest among the new cultivars of cluster-flowering camellia. Chlorophyll, carotenoid, and xanthophyll contents can be used as the key indicators to analyze the short-term high temperature stress, while chlorophyll a/b, Fv/Fm, qP, and qN can be used as the key indicators to analyze the long-term high temperature stress of Camellia.

The global agricultural productivity has been significantly impaired due to the extensive use of heavy metal. Cadmium (Cd) is now recognized as a significant soil and environmental contaminant that is primarily spread by human activity. This study investigates the possible impact of melatonin (ME) in mitigating the toxicity caused by Cd in pepper (Capsicum annuum L.) seedlings. There were three groups of plants used in the experiment: control (CK) plants, Cd-stressed plants and ME-pretreated + Cd-stressed plants. The concentration of ME and Cd was 1 µM and 0.1 mM, respectively, and applied as root application. The results described that Cd treatment remarkably reduced growth parameters, impaired pigment concentration, hindered gas exchange traits. In contrast, ME supplementation significantly recovered these parameters by increase in growth and biomass production of pepper seedlings under Cd toxicity. In addition, ME application considerably increased osmolyte production and protein level in pepper leaves and roots. Furthermore, ME positively upregulated the antioxidant enzymes activity and effectively decreased the oxidative damage in pepper leaves and roots. The enhanced antioxidant enzymes activity performed a significant role in the reduction of H2O2 and MDA concentration in plants under Cd stress. The findings indicated that the application of ME to plants effectively alleviates the stress caused by Cd exposure. Moreover, ME demonstrates significant efficacy in mitigating the adverse impacts of Cd on pepper plants. [ABSTRACT FROM AUTHOR]

In saline conditions, establishing healthy seedlings is crucial for the productivity of sunflowers (Helianthus annuus L.). Excessive potassium (K+) from irrigation water or overfertilization, similar to sodium (Na+), could adversely affect sunflower growth. However, the effects of salt stress caused by varying K/Na ratios on the establishment of sunflower seedlings have not been widely studied. We conducted a pot experiment in a greenhouse, altering the K/Na ratio of a soil solution to grow sunflower seedlings. We tested three saline solutions with K/Na ratios of 0:1 (P0S1), 1:1 (P1S1), and 1:0 (P1S0) at a constant concentration of 4 dS m−1, along with a control (CK, no salt added), with five replicates. The solutions were applied to the pots via capillary rise through small holes at the bottom. The results indicate that different K/Na ratios significantly influenced ion-selective uptake and transport in crop organs. With an increasing K/Na ratio, the K+ concentration in the roots, stems, and leaves increased, while the Na+ concentration decreased in the roots and stems, with no significant differences in the leaves. Furthermore, an excessive K/Na ratio (P1S0) suppressed the absorption and transportation of Mg2+, significantly reducing the Mg2+ concentration in the stems and leaves. A lower leaf Mg2+ concentration reduced chlorophyll concentration, impairing photosynthetic performance. The lowest plant height, leaf area, dry matter, and shoot/root ratio were observed in P1S0, with reductions of 27%, 48%, 48%, and 13% compared to CK, respectively. Compared with CK, light use efficiency and CO2 use efficiency in P1S0 were significantly reduced by 13% and 10%, respectively, while water use efficiency was significantly increased by 9%. Additionally, improved crop morphological and photosynthetic performance was observed in P1S1 and P0S1 compared with P1S0. These findings underscore the critical role of optimizing ion composition in soil solutions, especially during the sensitive seedling stage, to enhance photosynthesis and ultimately to improve the plant’s establishment. We recommend that agricultural practices in saline regions incorporate tailored irrigation and fertilization strategies that prioritize optimal K/Na ratios to maximize crop performance and sustainability.

Increased soil salinity significantly inhibits crop production around the world. Over the last decade, biochar has been used in agriculture to improve plant productivity, soil quality, and as an alternative to plant amendment. This study was aimed to study the effect of biochar, NPK, and their combination on the growth, physio-biochemical traits, mineral contents, and grain yield of barley (Hordeum vulgare L.). Thus, a pot factorial experiment based on a completely randomized design with three replications was performed. Experimental treatments included four levels of biochar (0, 2, 5 and 10% of total pot mass), four different NaCl levels (0, 75, 125, and 200 mmol L−1), and with or without NPK fertilizer. The results showed that a negative effect on gas exchange parameters, photosynthetic pigments, SPAD value, minerals contents, and grain yield of barley under salinity treatments. In addition, our funding showed the negative effect on biochemical traits such as proline, soluble sugars, individual sugar, and phenolic compounds. The use of biochar, combined with NPK fertilizers, considerably increases these parameters and especially improves barley grains yield under severe salinity conditions (200 mM) with a dose of 2% and 5% (394.1 and 280.61 g m−2, respectively) of total pot mass. It is concluded that biochar amendment could be a promising practice to enhance barley growth under severe saline irrigation and NPK fertilization regimes. [ABSTRACT FROM AUTHOR]

Under field conditions high temperatures are usually associated to high light intensity for periods of time that are getting longer because of global warming caused by climate change. These adverse conditions lead to significant reductions in yield and fruit quality in crops of great economic relevance such as citrus. In this work, the effect of high temperatures and high light intensity occurring alone or simultaneously has been studied in Carrizo citrange plants, a citrus genotype widely used as a rootstock, and the mitigating effect of kaolin (KL) evaluated. The combined stress conditions affected the plants in a unique manner at both, physiological and hormonal regulation levels, different to the effects of each individual stress. KL alleviated the deleterious effect of combined stress in different ways: (i) reducing leaf damage and abscission, (ii) improving physiological and gas exchange parameters, (iii) decreasing foliar proline content, (iv) increasing chlorophyll content, (v) preventing carotenoid degradation, and (vi) modulating levels of hormones and their precursors involved in plant responses to stress [abscisic acid (ABA), salicylic acid (SA), cinnamic acid (CA), indole-3-acetic acid (IAA), jasmonic acid (JA) and 12-oxophytodienoic acid (OPDA)]. [ABSTRACT FROM AUTHOR]

The objective of the study is to investigate the mechanism by which summer pruning enhances the growth of pepper plants, as indicated by growth and fruit appearance indicators, photosynthetic rate and gas exchange parameters, rapid light response and induction kinetics curves and the related chlorophyll fluorescence parameters. The results indicated that the leaf growth rate, the individual pepper fruit weight, and the fruit longitudinal and cross diameters of the pruned group were significantly higher than those of the control. The stomatal conductance (Gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr) of the pruned group were significantly higher than those of the control. The initial slope of the rapid light response curve, which represents light energy utilisation efficiency (a), the maximum electron transfer rate (Jmax) and saturated light intensity (PARsat) were all higher in the summer pruning group than in the control group. The F0 of the pruned group decreased by 16.83%, Fv/F0 increased by 23.69%, PIabs increased by 58.33%, and DIo/RC decreased by 22.09% compared to the control group. In summary, summer pruning significantly improves the leaf growth rate and fruit appearance quality of pepper, effectively promotes the photosynthesis of functional leaves, and reduces the degree of stress under adverse environmental conditions. [ABSTRACT FROM AUTHOR]

The effects of sulfate on the zinc (Zn) bioaccumulation characteristics and photophysiological mechanisms of the ornamental plant Hydrocotyle vulgaris were explored using a hydroponic culture under three Zn concentrations (300, 500 and 700 mg L−1) with (400 μmol L−1) or without the addition of sulfate. Results showed that: (1) tissue Zn concentrations and total Zn contents increased with increasing hydroponic culture Zn concentrations; and sulfate addition decreased Zn uptake and translocation from roots to shoots; (2) Zn exposure decreased photosynthetic pigment synthesis, while sulfate changed this phenomenon, especially for chlorophyll a under 300 mg L−1 Zn treatment; (3) Zn exposure decreased photosynthetic function, while sulfate had positive effects, especially on the photosynthetic rate (Pn) and stomatal conductance (Gs); and (4) chlorophyll fluorescence parameters related to light energy capture, transfer and assimilation were generally downregulated under Zn stress, while sulfate had a positive effect on these processes. Furthermore, compared to photosynthetic pigment synthesis and photosynthesis, chlorophyll fluorescence was more responsive, especially under 300 mg L−1 Zn treatment with sulfate addition. In general, Zn stress affected photophysiological processes at different levels, while sulfate decreased Zn uptake, translocation, and bioaccumulation and showed a positive function in alleviating Zn stress, ultimately resulting in plant growth promotion. All of these results provide a theoretical reference for combining H. vulgaris with sulfate application in the bioremediation of Zn-contaminated environments at the photophysiological level. Excessive zinc reduces the photosynthetic levels of plants. In this study, we investigated how damage caused by Zn stress may be alleviated. We found that exogenous sulfate could improve the photosynthetic levels of the ornamental plant Hydrocotyle vulgaris under Zn stressed. The results of this study provide a reference for the restoration of Zn-contaminated environments by the combining of H. vulgaris with sulfate at the photophysiological level. [ABSTRACT FROM AUTHOR]

Chilling injury can adversely affect strawberry bud differentiation, pollen vitality, fruit yield, and quality. Photosynthesis is a fundamental process that sustains plant life. However, different strawberry varieties exhibit varying levels of cold adaptability. Quantitatively evaluating the physiological activity of the photosynthetic system under low-temperature chilling injury remains a challenge. In this study, we investigated the effects of different levels of chilling stress on twenty photosynthetic fluorescence parameters in strawberry plants, using short-day strawberry variety "Toyonoka" and day-neutral variety "Selva" as representatives. Three dynamic chilling treatment levels (20/10 °C, 15/5 °C, and 10/0 °C) and three durations (3 days, 6 days, and 9 days) were applied to each variety. WUE, LCP, Y(II), qN, S I F O 2 - B and r S I F O 2 - B were selected as crucial indicators of strawberry photosynthetic physiological activity. Subsequently, we constructed a comprehensive score to assess the strawberry photosynthetic system under chilling injury and established a hyperspectral inversion model for stress quantification. The results indicate that the short-day strawberry "Toyonoka" exhibited a recovery effect under continuous 20/10 °C treatment, while the day-neutral variety "Selva" experienced progressively worsening stress levels across all temperature groups, with stress severity higher than that in "Toyonoka". The BPNN model for the comprehensive assessment of the strawberry photosynthetic system under chilling injury showed optimal performance. It achieved a stress level prediction accuracy of 71.25% in 80 validation samples, with an R2 of 0.682 when fitted to actual results. This study provides scientific insights for the application of canopy remote sensing diagnostics of strawberry photosynthetic physiological chilling injury in practical agricultural production. [ABSTRACT FROM AUTHOR]

Rodents, such as those that feed on plants and nest in plant roots, can significantly affect the growth and development of desert plants. The aim of this study was to investigate the effects of Rhombomys opimus disturbance on the photosynthetic characteristics and nutrient status of Haloxylon ammodendron at different growth stages in the Gurbantunggut Desert. The effects of great gerbil disturbance on the photosynthetic characteristics of H. ammodendron at different growth stages were investigated by measuring the gas exchange parameters, instantaneous water use efficiency, and chlorophyll fluorescence parameters of H. ammodendron at different ages (young, middle, and adult) under the disturbance of great gerbils. The soil nutrients in the assimilated branches and rhizosphere of H. ammodendron at different growth stages were tracked to reveal the relationship between the H. ammodendron nutrient content and gerbil disturbance. The results showed that great gerbil disturbance decreased the organic carbon content in the rhizosphere soil of adult H. ammodendron and increased the total nitrogen content in the rhizosphere soil and the nitrogen and potassium contents in the assimilated branches at each growth stage. The net photosynthetic rate and instantaneous water use efficiency of H. ammodendron decreased at each growth stage, and the maximum photochemical efficiency and non-photochemical quenching parameters of the young H. ammodendron decreased. However, the actual photochemical efficiency and photochemical parameters of the middle H. ammodendron increased. It was concluded that the disturbance of great gerbils decreased the photosynthetic capacity of H. ammodendron and increased the content of total nitrogen in the soil and nitrogen and potassium in the plant. This study revealed that the Gurbantunggut Desert great gerbil and H. ammodendron do not have a simple predation relationship. It laid a foundation for the study of the moderate disturbance threshold and better use of the mutually beneficial relationship between the two.

Global climate change has significantly increased the frequency and intensity of high temperature and drought stresses. Additionally, the high temperature and drought are often concurred, which make the situation of maize production tougher. However, the influence of the combined stresses of high temperature and drought on summer maize production remains uncertain. The study aimed to investigate the effects of high temperature, drought, and their combined stress at different growth stages on photosynthetic and senescence characteristics of summer maize. Denghai 605 (DH605) was used as the experimental material. High temperature (T), drought (D), and their combined stress (T-D) for 6 days were set at the 3rd leaf stage, 12th leaf stage, and tasseling stage, respectively. The natural temperature and normal water management were used as the control (CK). The results showed that high temperature, drought, and their combined stress at different growth stages decreased the activities of antioxidant enzymes and soluble protein content in leaves, leading to increases in MDA content and damage to cell membranes, which accelerated the senescence of the plant. Accordingly, the activities of RuBPcase and PEPCase were decreased, indicating the abilities of plants to harvest and utilize light energy declined due to high temperature, drought, and combined stresses at different growth stages. As a result, the Pn and thus, the dry matter accumulation rate were decreased by these stresses. In addition, the translocation of dry matter to ears was impeded by stresses, especially by the high temperature at the VT stage. While, high temperatures concurred with drought aggravated the adverse effects on summer maize, compared with single stresses. Significantly, high temperature, drought, and their combined stresses at the VT stage decreased the yield mostly, followed by stresses at the V12 stage, and then by stresses at the V3 stage. Compared with CK, the yield of VT-T-D, V12-T-D, and V3-T-D were decreased by 61.6 %, 13.7 %, and 10.4 %, respectively. As global climate change is unstoppable, the superimposed changes of various meteorological factors make the growth conditions for crop production extreme. Studies to explore the combined effects of two or even more meteorological factors on crop growth are becoming more and more important. This study fulfilled the current knowledge gap of the combined stresses on maize production, however, the underlying mechanisms should be dug out in the future.

Owing to global climate changes, periods of soil drought or waterlogging occur. Each of these factors causes negative effects on plant physiological processes and growth. Weeds are another factor that limits plant productivity. The main task of this study is to investigate the physiological reactions of triticale to herbicide treatment and subsequent drought or waterlogging. Young triticale plants were treated with Serrate® (selective herbicide produced by Syngenta) and exposed for 7 days to drought or waterlogging. Plant growth, chlorophyll and carotenoids content, the net photosynthesis rate and chlorophyll a fluorescence were measured during the stress period and after 4 days of plant recovery. Herbicide by itself did not induce considerable changes in the abovementioned parameters during the stress period. Serrate® did not affect strongly the efficiency of the photosynthetic machinery under harsh conditions. A significant reduction in fresh weight (85%), water content (93%), net photosynthesis rate, chlorophyll a fluorescence indices Fv/Fm and Fv/F0, and leaf pigments (58% for chlorophyll a, 53% for chlorophyll b, and 45% for carotenoids) was found because of drought. Waterlogging also influenced negatively these parameters but to a smaller extent. After resuming the normal irrigation, the photosynthesis and chlorophyll a fluorescence tended to increase and showed signs of recovery. The comparative analysis of growth and photosynthetic parameters demonstrated that triticale plants subjected to waterlogging could recover to a higher degree than those exposed to drought. [ABSTRACT FROM AUTHOR]

Copper (Cu) is an abundant essential micronutrient element in various rocks and minerals and is required for a variety of metabolic processes in both prokaryotes and eukaryotes. However, excess Cu can disturb normal development by adversely affecting biochemical reactions and physiological processes in plants. However, organic soil is rich in micronutrients and can assist plants to tolerate toxicity by promoting growth and biomass. This study explored the potential of organic and Cu-contaminated soil on fibrous jute (Corchorus capsularis). Plants were grown in the organic soil, natural soil (normal soil) and Cu-contaminated soil for 60 days, and we studied different growth, physiological and ultra-structure alterations in the plant. Results showed that the addition of organic acid in the soil showed a remarkable increase in seed germination, plant height, fresh biomass, photosynthetic pigment and gas exchange parameters, and decreased the malondialdehyde (MDA) concentration in the tissues when compared to the plants grown in the natural soil. In contrast, plants grown in the Cu-contaminated soil significantly (P < 0.05) decreased the seed germination, plant height, fresh biomass, photosynthetic pigment and gas exchange parameters, and increased MDA content, proline concentration and the activities of various antioxidant compounds; i.e. peroxidase (POD) and superoxidase dismutase (SOD). In addition, Cu toxicity also destroyed many membrane bounded organelles especially the chloroplast, which was revealed from transmission electron microscopy (TEM). We concluded that Cu toxicity affected growth and physiological attributes in C. capsularis , while addition of organic soil increased plant growth and biomass. An excessive amount of copper (Cu) reduces plant growth and biomass, lowering agricultural production and productivity. An organic soil may be found that improves seed germination in addition to plant growth and development. The growth, biomass, seed germination, photosynthesis pigments and plant exchange indices of Corchorus capsularis were all increased by organic soil. It is possible to increase C. capsularis biomass and growth by using organic soil in the field. [ABSTRACT FROM AUTHOR]

Mung bean, a legume, is sensitive to abiotic stresses at different growth stages, and its yield potential is affected by drought and high-temperature stress at the sensitive stage. Melatonin is a multifunctional hormone that plays a vital role in plant stress defense mechanisms. This study aimed to evaluate the efficiency of melatonin under individual and combined drought and high-temperature stress in mung bean. An experiment was laid out with five treatments, including an exogenous application of 100 µM melatonin as a seed treatment, foliar spray, and a combination of both seed treatment and foliar spray, as well as absolute control (ambient condition) and control (stress without melatonin treatment). Stresses were imposed during the mung bean's reproductive stage (31–40 DAS) for ten days. Results revealed that drought and high-temperature stress significantly decreased chlorophyll index, Fv/Fm ratio, photosynthetic rate, stomatal conductance, and transpiration rate through increased reactive oxygen species (ROS) production. Foliar application of melatonin at 100 µM concentration enhanced the activity of antioxidant enzymes such as superoxide dismutase, catalase, and ascorbate peroxidase and the concentration of metabolites involved in osmoregulation and ion homeostasis; thereby, it improves physiological and yield-related traits in mung bean under individual and combined stress at the reproductive stage. [ABSTRACT FROM AUTHOR]

Elevated atmospheric CO2 concentration and soil water deficiency have posed some impacts on the plant growth, leaf gas exchange and biochemical characteristics of maize ( Zea mays L.). It is a high demand to explore the physiological and ecological responses of agricultural ecosystems to future climate change. This study aims to further understand the key processes and potential mechanisms of elevated atmospheric CO2 concentration and soil water deficiency on the growth, physiological and biochemical characteristics of maize. Eight environmental growth chambers were employed to examine the changes in plant biomass, stomatal morphology and distribution, leaf gas exchange, and chlorophyll fluorescence of maize with the ambient CO2 concentration (400 μmol/mol) and elevated CO2 concentration (800 μmol/mol) along a soil water gradient, including full irrigation (75%~85% FC), mild water deficiency (65%~75% FC), moderate water deficiency (55%~65% FC), and severe water deficiency (45%~55% FC). A split-plot experiment was designed with two factors of CO2 concentration and watering, where CO2 concentration was the main plot with two levels, and watering was the subplot with four water treatments. Environmental growth chambers were selected to control the CO2 treatments with high-purity CO2 source from a CO2 bottle tank. Specifically, the CO2 concentration was maintained at an ambient CO2 concentration of 400 μmol/mol in four environmental growth chambers, whereas, the target CO2 concentration in the other four chambers was supplied with the elevated CO2 concentration (800 μmol/mol). The results showed that the soil water deficiency significantly decreased the aboveground biomass (P<0.05), but the elevated CO2 concentration increased the aboveground biomass and the total biomass of maize plants under mild water deficiency. Meanwhile, the contents of nitrogen and nonstructural carbohydrates in leaves were also outstandingly enhanced by the elevated CO2 concentration. Moreover, the elevated CO2 concentration substantially increased by 15.8% (P<0.05) and 25.7% (P=0.001), respectively, in the net photosynthetic rates (Pn ) of maize plants under mild and moderate water deficiency, indicating the strong CO2 fertilization effect on maize plants. However, the leaf transpiration rate ( Tr ) and stomatal conductance (G s ) were significantly declined by elevated CO2 concentration. Thus, the leaf-level water use efficiency (WUEI) was drastically enhanced under elevated CO2 concentration (P<0.001). Furthermore, the elevated CO2 concentration resulted in the decrease of chlorophyll under mild water deficiency. There was a significant increase in the photosynthetic electron transport rate (ETR) and photochemical quenching coefficient (qP) of maize plants subjected to mild water deficiency. Additionally, the soil water deficiency also dominated the stomatal density and morphology of maize leaves. But the most regular pattern of stomatal distribution was found on maize leaves under mild water deficiency. Therefore, the maize plants under mild water deficiency can benefit from the higher CO2 concentration with “CO2 fertilization effect” via plant biomass accumulation, leaf photosynthesis, and water use efficiency of maize. Thus, the deficiency irrigation during the growth of maize plants can be expected to serve as “ CO2 fertilization effect” from the future higher atmospheric CO2 concentration. The finding can also provide scientific evidence to determine the physiological and ecological mechanisms of maize, in response to the elevated atmospheric CO2 and soil water deficiency under future climate change. [ABSTRACT FROM AUTHOR]

This study investigated the effects of cerium (Ce) on the growth and fruit quality of strawberries under salt stress. The findings revealed that salt stress markedly enhanced the activities of antioxidant enzymes and increased the contents of malonaldehyde (MDA) and hydrogen peroxide (H2O2) in leaves and the contents of anthocyanins, phenolic compounds, vitamin C (Vc), soluble sugar (SS) and titratable acid (TA) in fruits. Ce markedly improved the activities of ascorbate peroxidase, superoxide dismutase, peroxidase and catalase in leaves and the contents of anthocyanins, phenolic compounds, Vc and SS in fruits, but significantly decreased MDA and H2O2 levels in leaves and TA content in fruits under salt stress. However, salt stress significantly decreased the contents of chlorophyll (Chl) and carotenoids (Car), photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (gs), relative water content (RWC), plant height and biomass, and fruit weight and sugar-acid ratio (SAR). Compared with salt stress alone, Ce obviously increased Chl and Car contents, Pn, Tr, gs, RWC, plant height and biomass, as well as fruit weight and SAR. The above results suggested that Ce showed beneficial effects on the growth and fruit quality of strawberries under salt stress.

Abstract Background The potato (Solanum tuberosum L.) is an important food crop in the alkaline soil area of northwest China. It is abundant in ascorbic acid (vitamin C), which facilitates iron absorption in the body. The large consumption of potato makes it a good food source of iron absorption for human body. However, iron deficiency in alkaline soil regions reduced chlorophyll synthesis in the leaves, resulting in lower photosynthesis and less sugar supply to the plant's healthy organs, significantly restricted crop development and yield, and inflicted major economic losses. Methods In this study, a 2-year (2020–2021) field trial was designed. Under foliar application of five different iron fertilizers: ferric sulfate [(Fe2(SO4)3], T1; ferrous sulfate (FeSO4·7H2O), T2; citric acid/ferric sulfate (CA/Fe2(SO4)3), T3; citric acid/ferrous sulfate (CA/FeSO4·7H2O), T4; ethylenediamine tetra acetic acid (EDTA-Fe·Na), T5, changes in potato plant photosynthesis were compared to no iron fertilization, CK conditions. The effects of various iron fertilizers on the yield, quality, and iron content of potato tubers, their correlations to chlorophyll levels, and the characteristics of photosynthetic fluorescence were studied. Results The results indicated that spraying iron fertilizers increased the yield, quality and Fe content of the tubers, which might be due to the improvement of the plants’ photosynthetic pigment content, gas exchange parameters and chlorophyll fluorescence. In two consecutive years of cultivation, we found that potato tuber yield and Fe content increased in potatoes treated with five iron fertilizer sprays. Among them, tuber yield increased most significantly by T5 and T3 treatments compared to CK, while Fe content was significantly higher by the T5 treatment than by CK and other treatments. Tuber yield was increased by 33.28% and 18.85% in 2020 and 50.74% and 54.48% in 2021 by T5 and T3 treatments, respectively, compared to CK. Fe content was increased by 112.64% and 54.98% in 2020 and 2021 by T5 treatment, respectively, compared to CK. Conclusions EDTA-Fe·Na and CA/Fe2(SO4)3 excelled over the other iron fertilizers. The findings of this study are instructive for developing cost-effective iron fertilizer management systems to maximize the impact of iron biofortification on human health. Graphical Abstract

Summary: We present a robust estimation of the CO2 concentration at the surface of photosynthetic mesophyll cells (cw), applicable under reasonable assumptions of assimilation distribution within the leaf. We used Capsicum annuum, Helianthus annuus and Gossypium hirsutumas model plants for our experiments.We introduce calculations to estimate cw using independent adaxial and abaxial gas exchange measurements, and accounting for the mesophyll airspace resistances.The cw was lower than adaxial and abaxial estimated intercellular CO2 concentrations (ci). Differences between cw and the ci of each surface were usually larger than 10 μmol mol−1. Differences between adaxial and abaxial ci ranged from a few μmol mol−1 to almost 50 μmol mol−1, where the largest differences were found at high air saturation deficits (ASD). Differences between adaxial and abaxial ci and the ci estimated by mixing both fluxes ranged from −30 to +20 μmol mol−1, where the largest differences were found under high ASD or high ambient CO2 concentrations.Accounting for cw improves the information that can be extracted from gas exchange experiments, allowing a more detailed description of the CO2 and water vapor gradients within the leaf. [ABSTRACT FROM AUTHOR]

China is the largest kiwifruit producer in the world, accounting for more than half of the total. However, in terms of yield per unit area, China is much lower than the global average and lags behind that of other countries. Yield improvement is of critical importance for the current kiwifruit industry in China. In this study, an improved overhead pergolas trellis (OPT) system, namely, the umbrella-shaped trellis (UST) system, was developed for Donghong kiwifruit, which is now the second most popular and widely cultivated red-fleshed kiwifruit in China. Surprisingly, the estimated yield on the UST system was more than two times higher than that with a traditional OPT, while the external fruit quality was maintained and the internal fruit quality was improved. One of the mechanisms contributing to the yield improvement was the significant promotion of the vegetative growth of canes at 6 ~ 10 mm in diameter by the UST system. The upper canopy of the UST treatment served as a natural shading condition for the lower fruiting canopy and thus had positive effects on the accumulation of chlorophylls and total carotenoids in the fruiting canopy. The most productive zones on the fruiting canes (6 ~ 10 mm in diameter) contained significantly higher (P < 0.05) levels of zeatin riboside (ZR) and auxin (IAA) and ratios of ZR/gibberellin (GA), ZR/abscisic acid (ABA), and ABA/GA. A relatively high carbon/nitrogen ratio may promote the flower bud differentiation process of Donghong kiwifruit. The outcomes of this study provide a scientific basis for manifold increase in production of kiwifruit and contribute to the sustainability of the kiwifruit industry. [ABSTRACT FROM AUTHOR]

Increased soil salinity significantly inhibits crop production around the world. Over the last decade, biochar has been used in agriculture to improve plant productivity, soil quality, and as an alternative to plant amendment. This study was aimed to study the effect of biochar, NPK, and their combination on the growth, physio-biochemical traits, mineral contents, and grain yield of barley (Hordeum vulgare L.). Thus, a pot factorial experiment based on a completely randomized design with three replications was performed. Experimental treatments included four levels of biochar (0, 2, 5 and 10% of total pot mass), four different NaCl levels (0, 75, 125, and 200 mmol L−1), and with or without NPK fertilizer. The results showed that a negative effect on gas exchange parameters, photosynthetic pigments, SPAD value, minerals contents, and grain yield of barley under salinity treatments. In addition, our funding showed the negative effect on biochemical traits such as proline, soluble sugars, individual sugar, and phenolic compounds. The use of biochar, combined with NPK fertilizers, considerably increases these parameters and especially improves barley grains yield under severe salinity conditions (200 mM) with a dose of 2% and 5% (394.1 and 280.61 g m−2, respectively) of total pot mass. It is concluded that biochar amendment could be a promising practice to enhance barley growth under severe saline irrigation and NPK fertilization regimes.

In the present study, hydroponic experiments were performed to explore the mechanistic role of H2S (NaHS (donor of H2S); 40 μM) in alleviating NaCl stress in brinjal and tomato seedlings by analyzing the growth, pigments content, gas exchange parameters, and contents of inorganic nitrogen and activities of enzymes involved in N2 metabolism. While NaCl at 20 mM declined the growth (tolerance index (TI) and plant height), pigment content (total chlorophyll and Chl a/b), and gas exchange parameters (intercellular CO2 concentration; Ci, net photosynthetic rate; A, transpiration rate; E, stomatal conductance; Gs). It also variably affected the inorganic N (NO3−, NO2− and NH4+) content, and the enzymes involved in nitrate (nitrate reductase; NR and nitrite reductase; NiR), and ammonium (glutamine synthetase; GS, glutamate synthase; GOGAT and Glutamate dehydrogenase; GDH) assimilation, whereas the supplementation of H2S showed considerable improvement in all the studied parameters. Furthermore, the addition of H2S scavenger hypotaurine (HT; 200 μM) to NaCl + NaHS seized all the recovery on the above parameters caused by the NaHS treatment, suggesting the role of exogenous H2S. While, the addition of an inhibitor of H2S generation propargylglycine (PAG; 100 μM) to NaCl treatments further declined the growth more than NaCl treatment alone, implying the role of endogenous H2S. Altogether, our study highlights the modulatory role of endogenous and exogenous H2S in conferring NaCl stress tolerance in brinjal and tomato seedlings by maintaining the ion homeostasis and the C/N ratio.

Research on mitigating the effects of water scarcity by applying silicon to perennial grasses is still insufficient. This study was conducted to investigate the effect of spring and summer droughts and silicon applications on gas exchange parameters; the morphometric characteristics of root systems; and the biomass distribution of Festulolium braunii, Festuca arundinacea, and Lolium perenne cultivars. Plants were treated with a drought during the tillering phase once a year (during spring or summer regrowth) for 21 days. Foliar nutrition with silicon was applied twice under the drought conditions. Grasses in a pot experiment were cut three times during vegetation. The plants that were exposed to the drought had lower values of the gas exchange parameters than those that were well watered. The beneficial effect of silicon was related to the reduction of excessive water loss through transpiration during the spring drought. Under the drought and silicon applications, the water use efficiency, root dry mass, and length increased compared to the control. Moreover, silicon increased the proportion of both the finer and thicker roots in F. braunii and L. perenne, while the distribution of the root diameter changed least in the more resistant F. arundinacea. Silicon also reduced the carbon content in the roots and increased root carbon accumulation. Our results indicated that Si may help perennial forage grasses cope better with drought stress. This was due to the allocation of carbon to the roots to develop the fine root network, increasing the length and root biomass and improving the water use efficiency. [ABSTRACT FROM AUTHOR]

Copyright of Asian Journals of Ecotoxicology is the property of Gai Kan Bian Wei Hui 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.)

• Seedling responses to drought were assessed by cultivation experiments. • R. pseudoacacia had higher drought resilience than P. tabuliformis. • The daily ET was highly promoted by R n when rainfall > 300 mm. • P. tabuliformis had higher water use efficiency than R. pseudoacacia. Seedling survival is vital for ecological restoration and carbon neutrality on the Loess Plateau, yet large-scale afforestation in North China has reduced soil water availability in arid and semi-arid areas, complicating efforts to sustain young trees. The water consumption strategies of commonly planted trees and their eco-hydrological responses to varying water conditions remain unclear. Two common tree seedlings, Robinia pseudoacacia and Pinus tabuliformis , were cultivated using soil column experiments to simulate the initial stage of afforestation. Six irrigation treatments (in 100, 200, 300, 400, 500 and 600 mm) were applied to investigate the effect of rainfall recharge on tree physiological traits and water consumptions from June to August in 2021–2022. Results indicated that the both species experienced reduced leaf gas exchange under drought (<200 mm) and flood (>500 mm), and it was decreased when the vapour pressure deficit >2 kPa. R. pseudoacacia exhibited lower stomatal conductance and transpiration but higher leaf water use efficiency than P. tabuliformis under drought, indicating better drought resilience. The daily evapotranspiration (ET) of the two species was both limited by soil moisture when irrigation <300 mm, while it was promoted by solar radiation when irrigation > 300 mm. A precipitation threshold of 300 mm was identified as critical for seedling growth. Moreover, the mean ET of R. pseudoacacia and P. tabuliformis was 190.43–648.40 and 196.30–620.40 mm, respectively, in the 100–600 mm irrigation treatments during June to August in 2021–2022, and the mean water use efficiency of P. tabuliformis was 55.1 % higher than that of R. pseudoacacia at the plant level. This study will provide critical insights into water consumption strategies to water stress on early afforestation, offering guidance for species selection and ecological restoration on the Loess Plateau. [ABSTRACT FROM AUTHOR]

Soil salinization effects plant photosynthesis in a number of global ecosystems. In this study, photosynthetic and physiological parameters were used to elucidate the impacts of saline-alkaline stress on Cyperus esculentus L. (C. esculentus) seedling photosynthesis. The results demonstrate that salt stress, alkali stress and mixed salt and alkali stress treatments all have similar bell-shaped influences on photosynthesis. At low concentrations (0−100 mmol L−1), saline-alkaline stress promoted net photosynthetic rate, transpiration rate and water use efficiency in C. esculentus. However, as the treatments increased in intensity (100−200 mmol L−1), plant photosynthetic parameters began to decline. We interpreted this as the capacity of C. esculentus to improve osmoregulatory capacity in low saline-alkaline stress treatments by accumulating photosynthetic pigment, proline and malondialdehyde to counterbalance the induced stress – an adaptive mechanism that failed once concentrations reached a critical threshold (100 mmol L−1). Stomatal conductance, maximum photosynthetic rate and actual photosynthetic rate all decreased with increasing concentration of the stress treatments, and intercellular carbon dioxide showed a decreasing and then increasing trend. These results indicated that when the saline-alkaline stress concentrations were low, C. esculentus seedlings showed obvious adaptive ability, but when the concentration increased further, the physiological processes of C. esculentus seedlings were significantly affected, with an obvious decrease in photosynthetic efficiency. This study provides a new understanding of the photosynthetic adaptation strategies of C. esculentus seedlings to varying concentrations of saline-alkaline stress. • Photosynthesis in C. esculentus did not differ under saline-alkaline stress. • At low levels, C. esculentus adapted photosynthetically, showing salt tolerance. • Stomatal limitation is the dominant factor of low stress in C. esculentus seedlings. • High concentration impairs C. esculentus photosynthesis mechanisms. [ABSTRACT FROM AUTHOR]

Background: The potato (Solanum tuberosum L.) is an important food crop in the alkaline soil area of northwest China. It is abundant in ascorbic acid (vitamin C), which facilitates iron absorption in the body. The large consumption of potato makes it a good food source of iron absorption for human body. However, iron deficiency in alkaline soil regions reduced chlorophyll synthesis in the leaves, resulting in lower photosynthesis and less sugar supply to the plant's healthy organs, significantly restricted crop development and yield, and inflicted major economic losses. Methods: In this study, a 2-year (2020–2021) field trial was designed. Under foliar application of five different iron fertilizers: ferric sulfate [(Fe2(SO4)3], T1; ferrous sulfate (FeSO4·7H2O), T2; citric acid/ferric sulfate (CA/Fe2(SO4)3), T3; citric acid/ferrous sulfate (CA/FeSO4·7H2O), T4; ethylenediamine tetra acetic acid (EDTA-Fe·Na), T5, changes in potato plant photosynthesis were compared to no iron fertilization, CK conditions. The effects of various iron fertilizers on the yield, quality, and iron content of potato tubers, their correlations to chlorophyll levels, and the characteristics of photosynthetic fluorescence were studied. Results: The results indicated that spraying iron fertilizers increased the yield, quality and Fe content of the tubers, which might be due to the improvement of the plants' photosynthetic pigment content, gas exchange parameters and chlorophyll fluorescence. In two consecutive years of cultivation, we found that potato tuber yield and Fe content increased in potatoes treated with five iron fertilizer sprays. Among them, tuber yield increased most significantly by T5 and T3 treatments compared to CK, while Fe content was significantly higher by the T5 treatment than by CK and other treatments. Tuber yield was increased by 33.28% and 18.85% in 2020 and 50.74% and 54.48% in 2021 by T5 and T3 treatments, respectively, compared to CK. Fe content was increased by 112.64% and 54.98% in 2020 and 2021 by T5 treatment, respectively, compared to CK. Conclusions: EDTA-Fe·Na and CA/Fe2(SO4)3 excelled over the other iron fertilizers. The findings of this study are instructive for developing cost-effective iron fertilizer management systems to maximize the impact of iron biofortification on human health. [ABSTRACT FROM AUTHOR]

Salinity is one of the most decisive environmental factors limiting crop productivity, especially in arid and semi-arid regions. The objective of this study was to evaluate the growth depression of spring maize (Zea mays L.) due to salinity stress caused by different drip irrigation regimes in an arid saline area. A two-year field experiment was conducted in the Hetao Irrigation District, northwest China in 2019 and 2020. The study soil was moderately saline with ECe (electrical conductivity of saturated soil extract) of 8.04 dS m-1. Three threshold values of soil matric potential (SMP), -10, -30, and -50 kPa, were used to trigger a 10-20 mm drip irrigation of spring maize. Nine plots were arranged in a randomized block design (with triplication for each SMP level). Results showed that the lower soil salinity caused by higher SMP levels significantly increased crop photosynthetic capacity and reduced salt cations (K+, Na+, Ca2+, Mg2+) concentrations in plant organs, thereby increasing aboveground biomass and grain yields. Gas exchange parameter values first increased and then decreased in the R1-R5 stage (76-115 DAP) except for net photosynthetic rate (Pn) of -10 kPa treatment. Four salt cations in the aboveground parts were mainly distributed in stems and leaves, followed by grains. However, there was no significant difference in aboveground cationic accumulation among treatments. Correlation analysis indicated that gas exchange parameter values were negatively correlated with concentrations of K+, Na+, Ca2+, and Mg2+ in aboveground plant organs at harvest, indicating that Pn could quantitatively reflect the salt ionic toxicity in crops to a large extent. Considering photosynthesis, salt cations absorption, and water use efficiency, an SMP threshold of -30 kPa is recommended for drip irrigation of maize in this arid saline condition. These findings can provide a theoretical basis and technical reference for the promotion of mulched drip irrigation under the arid saline condition. [ABSTRACT FROM AUTHOR]

Chilling injury can adversely affect strawberry bud differentiation, pollen vitality, fruit yield, and quality. Photosynthesis is a fundamental process that sustains plant life. However, different strawberry varieties exhibit varying levels of cold adaptability. Quantitatively evaluating the physiological activity of the photosynthetic system under low-temperature chilling injury remains a challenge. In this study, we investigated the effects of different levels of chilling stress on twenty photosynthetic fluorescence parameters in strawberry plants, using short-day strawberry variety “Toyonoka” and day-neutral variety “Selva” as representatives. Three dynamic chilling treatment levels (20/10 °C, 15/5 °C, and 10/0 °C) and three durations (3 days, 6 days, and 9 days) were applied to each variety. WUE, LCP, Y(II), qN, SIFO2-B and rSIFO2-B were selected as crucial indicators of strawberry photosynthetic physiological activity. Subsequently, we constructed a comprehensive score to assess the strawberry photosynthetic system under chilling injury and established a hyperspectral inversion model for stress quantification. The results indicate that the short-day strawberry “Toyonoka” exhibited a recovery effect under continuous 20/10 °C treatment, while the day-neutral variety “Selva” experienced progressively worsening stress levels across all temperature groups, with stress severity higher than that in “Toyonoka”. The BPNN model for the comprehensive assessment of the strawberry photosynthetic system under chilling injury showed optimal performance. It achieved a stress level prediction accuracy of 71.25% in 80 validation samples, with an R2 of 0.682 when fitted to actual results. This study provides scientific insights for the application of canopy remote sensing diagnostics of strawberry photosynthetic physiological chilling injury in practical agricultural production.

Owing to global climate changes, periods of soil drought or waterlogging occur. Each of these factors causes negative effects on plant physiological processes and growth. Weeds are another factor that limits plant productivity. The main task of this study is to investigate the physiological reactions of triticale to herbicide treatment and subsequent drought or waterlogging. Young triticale plants were treated with Serrate® (selective herbicide produced by Syngenta) and exposed for 7 days to drought or waterlogging. Plant growth, chlorophyll and carotenoids content, the net photosynthesis rate and chlorophyll a fluorescence were measured during the stress period and after 4 days of plant recovery. Herbicide by itself did not induce considerable changes in the abovementioned parameters during the stress period. Serrate® did not affect strongly the efficiency of the photosynthetic machinery under harsh conditions. A significant reduction in fresh weight (85%), water content (93%), net photosynthesis rate, chlorophyll a fluorescence indices Fv/Fm and Fv/F0, and leaf pigments (58% for chlorophyll a, 53% for chlorophyll b, and 45% for carotenoids) was found because of drought. Waterlogging also influenced negatively these parameters but to a smaller extent. After resuming the normal irrigation, the photosynthesis and chlorophyll a fluorescence tended to increase and showed signs of recovery. The comparative analysis of growth and photosynthetic parameters demonstrated that triticale plants subjected to waterlogging could recover to a higher degree than those exposed to drought.

Mung bean, a legume, is sensitive to abiotic stresses at different growth stages, and its yield potential is affected by drought and high-temperature stress at the sensitive stage. Melatonin is a multifunctional hormone that plays a vital role in plant stress defense mechanisms. This study aimed to evaluate the efficiency of melatonin under individual and combined drought and high-temperature stress in mung bean. An experiment was laid out with five treatments, including an exogenous application of 100 µM melatonin as a seed treatment, foliar spray, and a combination of both seed treatment and foliar spray, as well as absolute control (ambient condition) and control (stress without melatonin treatment). Stresses were imposed during the mung bean’s reproductive stage (31–40 DAS) for ten days. Results revealed that drought and high-temperature stress significantly decreased chlorophyll index, Fv/Fm ratio, photosynthetic rate, stomatal conductance, and transpiration rate through increased reactive oxygen species (ROS) production. Foliar application of melatonin at 100 µM concentration enhanced the activity of antioxidant enzymes such as superoxide dismutase, catalase, and ascorbate peroxidase and the concentration of metabolites involved in osmoregulation and ion homeostasis; thereby, it improves physiological and yield-related traits in mung bean under individual and combined stress at the reproductive stage.

Exogenously applied phytohormones improve the endosperm cells and establish greater kernel sink capacity and grain filling, improving grain yield. In this study, 28-Homobrassinolide (HBR) dosages (20, 25, and 30 mg a. i. ha−1) were applied separately at the silking stage under controlled conditions, and EDAH (a mixture of ethephon and diethyl aminoethyl hexanoate) dosage of 90 g a. i. ha−1 was sprayed at the jointing stage to enhance the lodging resistance. Our objective was to investigate whether the application of HBR under controlled conditions or with EDAH could enhance the grain filling rate by regulating endogenous hormones. The results showed that HBR at the silking stage significantly increased endogenous hormones (ABA, IAA, Z+ZR), hampered leaf senescence, enhanced photosynthetic, improved dry matter accumulation in grains, and increased the grain-filling period, filling rate, and thousand-grains weight. Additionally, HBR 25 and 30 mg a. i. ha−1 increased the final yield by 9.9% and 19.5% compared to the control (CK) in 2020 and 14.1% and 18.95% in 2021, respectively. There was no significant difference between the results obtained from HBR-controlled and EDAH treatments at the jointing stage. Thus, we conclude that spraying HBR 25~30 mg a. i. ha−1 under controlled conditions may increase the grain yield under normal weather conditions. In adverse weather conditions and heavy wind, spraying EDAH 90 g a. i. ha−1 at the jointing stage and HBR 30 mg a. i. ha−1 at the silking stage can enhance maize production. [ABSTRACT FROM AUTHOR]

Abstract Background The photosynthetic parameters of cotton plants may be modified by the timing of film removal during their growing period. This study was undertaken during 2015–2017 in Xinjiang, China, to determine to what extent the film mulching removal time, 1 and 10 days before the first irrigation and 1 day before the second irrigation after seedling emergence, influenced cotton’s photosynthetic characteristics. The control group (CK) was film-mulched throughout the growth stages. Results The results suggested the following: (1) Removing mulching-film within 50 days since seedling emergence had adverse effects on soil temperature and moisture. (2) Film-removal before the first or second irrigation after emergence improved the net photosynthetic rate in cotton’s later flowering stage and its transpiration rate in mid and later flowering stages while enhancing the actual electron transport rate (ETR) and maximum electron transfer rate (ETRmax) between cotton photosystems I and II. (3) Film-removal treatment also increased cotton plants’ tolerance to high irradiation after emergence, the trend was more pronounced in the early flowering stage in wetter years. (4) Leaf area index (LAI) of cotton was reduced in the film-removal treatment for which the least accumulation of dry matter occurred in a drought year (i.e., 2015). (5) Film removal caused a yield decrease in the dry year (2015), and the earlier the film was removed, the more seriously the yield decreased. Removing mulching film before the second irrigation could increase the yield of XLZ42 in the rainy year (2016) and the normal rainfall year (2017). Early film removal can increase the yield of XLZ45 in the rainy year (2016). Conclusions Collectively, our study’s experimental results indicate that applying mulch film removal at an appropriate, targeted time after seedling emergence had no adverse effects on soil moisture and temperature, and improved the photosynthetic performance of cotton, thus increased cotton yield and fiber quality, but no significant difference was reached.

To explore the critical relationships of photosynthetic efficiency and stem sap flow to soil moisture, two-year-old poplar saplings were selected and a packaged stem sap flow gauge, based on the stem-heat balance method, and a CIRAS-2 portable photosynthesis system were used. The results show that photosynthetic rates (Pn), transpiration rates (Tr), instantaneous water use efficiency (WUE) and the stem sap flow increased initially and then decreased with decreasing soil water, but their critical values were different. The turning point of relative soil water content (Wr) from stomatal limitation to nonstomatal limitation of Pn was 42%, and the water compensation point of Pn was 13%. Water saturation points of Pn and Tr were 64% and 56%, respectively, and the WUE was 71%. With increasing soil water, the apparent quantum yield (AQY), light saturation point (LSP) and maximum net photosynthetic rate (Pnmax) increased first and then decreased, while the light compensation point (LCP) decreased first and then increased. When Wr was 64%, LCP reached a lower value of 30.7 µmol m−2 s−1, and AQY a higher value of 0.044, indicating that poplar had a strong ability to utilize weak light. When Wr was 74%, LSP reached its highest point at 1138.3 µmol∙m−2 s−1, indicating that poplar had the widest light ecological amplitude and the highest light utilization efficiency. Stem sap flow and daily sap flow reached the highest value (1679.7 g d−1) at Wr values of 56% and 64%, respectively, and then declined with increasing or decreasing Wr, indicating that soil moisture significantly affected the transpiration water-consumption of poplar. Soil water was divided into six threshold grades by critical values to maintain photosynthetic efficiency at different levels, and a Wr of 64–71% was classified to be at the level of high productivity and high efficiency. In this range, poplar had high photosynthetic capacity and efficient physiological characteristics for water consumption. The saplings had characteristics of water tolerance and were not drought resistant. Full attention should be given to the soil water environment in the Yellow River Delta when planting Populus. [ABSTRACT FROM AUTHOR]

Research on mitigating the effects of water scarcity by applying silicon to perennial grasses is still insufficient. This study was conducted to investigate the effect of spring and summer droughts and silicon applications on gas exchange parameters; the morphometric characteristics of root systems; and the biomass distribution of Festulolium braunii, Festuca arundinacea, and Lolium perenne cultivars. Plants were treated with a drought during the tillering phase once a year (during spring or summer regrowth) for 21 days. Foliar nutrition with silicon was applied twice under the drought conditions. Grasses in a pot experiment were cut three times during vegetation. The plants that were exposed to the drought had lower values of the gas exchange parameters than those that were well watered. The beneficial effect of silicon was related to the reduction of excessive water loss through transpiration during the spring drought. Under the drought and silicon applications, the water use efficiency, root dry mass, and length increased compared to the control. Moreover, silicon increased the proportion of both the finer and thicker roots in F. braunii and L. perenne, while the distribution of the root diameter changed least in the more resistant F. arundinacea. Silicon also reduced the carbon content in the roots and increased root carbon accumulation. Our results indicated that Si may help perennial forage grasses cope better with drought stress. This was due to the allocation of carbon to the roots to develop the fine root network, increasing the length and root biomass and improving the water use efficiency.

[Objective] The differences in photosynthetic physiological characteristics of different lines of Baccaurea ramiflora Lour.were investigated to provide a scientific basis for the further selection of superior B.ramiflora Lour.varieties and their promotion in the field. [Method] The CIRAS-3 portable photosynthesizer was used to determine the gas exchange parameters of the leaves of six lines of grafted B.ramiflora Lour.seedlings, record each photosynthetic physiological parameter and analyze and compare the differences in photosynthetic physiological characteristics of different lines of B.ramiflora Lour.[Result] Among the photosynthetic physiological parameters of the six lines of B.ramiflora Lour.,transpiration rate (Tr), intercellular CO2 concentration (Ci), stomatal conductance(Gs), water vapor pressure deficit (VPD), water use efficiency (WUE), stomatal limitation value(Ls) and carboxylation efficiency (CE) varied greatly among the lines, with Tr ranging from 2.83 to 3.98 mmol/（m²·s）,Ci 260.70-287.10 μmol/mol, Gs was 81.10-128.90 mmol/(m²·s), VPD was 3.12-3.64 mb, WUE was 1.26-1.87 μmol/mmol, Ls was 0.25-0.32 μmol/(m2·s), and CE was 0.017%-0.025%;And net photosynthetic rate (Pn) ranged from 4.56 to 6.48 μmol/(m²·s) and light energy use efficiency(LUE) from 0.0038 to 0.0054 μmol/mmol, both of which were not significantly different among the lines (P>0.05). Obvious correlations were found among photosynthetic physiological indices of the six lines of B.ramiflora Lour.,in which Pn was highly significantly correlated(P<0.01) with LUE(r=1.000**), Pn with CE(r=0.972**), LUE with CE(r=0.972**),Ci with Ls(r=-0.997**);Tr with Gs(r=0.911*), and Ci with WUE(r=-0.834*) were significantly correlated(P<0.05). The results of cluster analysis showed that the six lines of B.ramiflora Lour.could be clustered into two types of lines, Jinghong No.5, Maogan No.3 and Shangnian No.1, which had better photosynthetic physiological characteristics, and Tanleng No.1, Pona No.1 and Xinglong No.2,which had average photosynthetic physiological characteristics.[Conclusion] There are differences in the photosynthetic physiological characteristics of different lines of B.ramiflora Lour.seedlings, of which Jinghong No.5, Maogan No.3 and Shangnian No.1 are more suitable for the promotion of B.ramiflora Lour.lines in the field, artificial cultivation management process should be based on their different photosynthetic characteristics to take appropriate measures to prevent sunlight and moisture. [ABSTRACT FROM AUTHOR]

This work compares the tolerance to long-term anoxia conditions (35 days) of five new citrus ‘King’ mandarin (Citrus nobilis L. Lour) × Poncirus trifoliata ((L.) Raf.) hybrids (named 0501XX) and Carrizo citrange (CC, Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.), the widely used citrus rootstock in Spain. Growth parameters, chlorophyll concentration, gas exchange and fluorescence parameters, water relations in leaves, abscisic acid (ABA) concentration, and PIP1 and PIP2 gene expressions were assessed. With a waterlogging treatment, the root system biomass of most hybrids went down, and the chlorophyll a and b concentrations substantially dropped. The net CO2 assimilation rates (An) and stomatal conductance (gs) lowered significantly due to flooding, and the transpiration rate (E) closely paralleled the changes in gs. The leaf water and osmotic potentials significantly increased in most 0501 hybrids. As a trend, flooding stress lowered the ABA concentration in roots from most hybrids, but increased in the leaves of CC, 05019 and 050110. Under the control treatment (Ct) conditions, most 0501 hybrids showed higher PIP1 and PIP2 expressions than the control rootstock CC, but were impaired due to the flooding conditions in 05019 and 050110. From this study, we conclude that 0501 genotypes develop some adaptive responses in plants against flooding stress such as (1) stomata closure to prevent water loss likely mediated by ABA levels, and (2) enhanced water and osmotic potentials and the downregulation of those genes regulating aquaporin channels to maintain water relations in plants. Although these traits seemed especially relevant in hybrids 050110 and 050125, further experiments must be done to determine their behavior under field conditions, particularly their influence on commercial varieties and their suitability as flooding-tolerant hybrids for replacing CC, one of the main genotypes that is widely used as a citrus rootstock in Spain, under these conditions. [ABSTRACT FROM AUTHOR]

In addition to irrigation, other viticultural practices such as soil management can be applied to improve grapevine (Vitis vinifera L.) quality responses and attenuate unfavourable environmental conditions. Cover crops in the interrow of irrigated vineyards change the dynamics of water extraction and it is expected that the patterns of vines’ water relations will be modified, also changing their productive responses. This study took place over two seasons in ‘Tempranillo’ grapevines in a vineyard in South Portugal, where a cover crop was sown in the inter-rows of half the study area (SCC) while maintaining resident vegetation in the remaining (RV). Five water regime treatments were applied: full irrigation (200 mm irrigation amount–I200); moderate irrigation (150 mm–I150); deficit irrigation (100 mm–I100); ultra-deficit irrigation (50 mm–I50); rainfed (I0). Measurements of predawn leaf water potential (ΨPD), stomatal conductance (gs), photosynthetic rate (An), and transpiration rate (E) were made during the final stages of the growth cycle. Data of soil water availability, yield and growth variables, and berries and wine composition were also used. Significant interactions between the effect of soil management and water regime were observed on ΨPD. A water competition effect exerted by the cover crop could be responsible for reduced water loss and carbon assimilation, whenever Spring rain is lower and/or the cover crop biomass development is not controlled. Differences in gs and An observed at midday and late measurements reflect the influence of the daily increase of atmospheric water demand. Stomatal closure of grapevines was less affected in plots of higher soil water storage capacity. The correlation between ΨPD and gs was higher in the midday and late measurements, pointing to the regulation of stomatal response in response to water availability and daily environmental conditions. Principal components analysis (PCA) evidenced an influence of water deficit on metabolic responses that benefit fruit and wine quality. The cluster analysis (CA) revealed that no significant cluster of cases was clearly controlled by soil management or water regime in the first season but, in the second, drier season, significant clustering more irrigation- than soil management-controlled showed that a predominant influence of irrigation should be expected for ‘Tempranillo’ grapevines grown under dry Mediterranean conditions.

Drought is known to be the most important constraint to the growth and yield of agricultural products in the world, and plant symbiosis with arbuscular mycorrhizal fungi (AMF) can be a way to reduce drought stress negative impacts. A two-year experiment to investigate the factorial combination of mycorrhizal fungi (Glomus mosseae , Glomus intraradices , Control) and phosphorus fertilizer (application and non-application of phosphorus) on fruit yield and phenolic acids changes bitter gourd under different irrigation regimes as a split factorial based on a randomized complete block design. Three irrigation regimes, including irrigation after 20%, 50%, and 80% available soil water content depletion (ASWD), were considered in the main plots. The results showed that under water deficit stress, fruit yield and physiological (photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), RWC, total chlorophyll, and root colonization) parameters decreased compared to 20% ASWD, and biochemical (proline, soluble sugar, MDA, CAT, SOD, phenol) parameters and fruit phenolic acids (caffeic acid, coumaric acid, ferulic acid) increased. However, the inoculation of AMF and phosphorus fertilizer in three irrigation regimes decreased MDA content, but physiological and biochemical parameters and fruit phenolic acids were increased. In this study, the factorial combination of AMF and sufficient phosphorus improved the resistance of bitter gourd to water deficit, and this not only improved fruit yield but also increased fruit phenolic acids under 80% ASWD, which can be an innovation in the management of water resources and the production industry of medicinal plants with high antioxidant properties in water deficit areas. [Display omitted] • Drought stress and AMF increase significantly the coumaric acid of bitter gourd fruit. • Drought stress increases MAD, decreases RWC and chlorophyll synthesis in bitter gourd. • AMF moderates drought stress by increasing of antioxidant enzymes activity and phenol. • Phosphorus fertilizer and AMF combination improves fruit yield under drought stress. • AMF improves gas exchange under drought stress by increasing root chlorination. [ABSTRACT FROM AUTHOR]