Search

The optimization of cotton defoliant application is critical for enhancing fiber quality and yield. This study aims to assess the impact of different defoliant duty cycles on cotton fiber quality by applying Principal Component Analysis (PCA) to High-Volume Instrument (HVI) data from two fields. Three duty cycles—20%, 40%, and 60%—along with a control treatment were evaluated. PCA was used to identify the key factors influencing cotton quality, with a focus on parameters such as fiber length, strength, and uniformity. The results revealed that the 40% duty cycle consistently produced the most stable and uniform cotton fiber quality across both fields, minimizing variability in critical parameters. In contrast, the 20% and 60% duty cycles, as well as the control, introduced greater variability, with the control treatment showing the most significant outliers. These findings suggest that a 40% duty cycle is optimal for balancing effective defoliation with high-quality cotton production. Future research should explore the robustness of the 40% duty cycle across different environmental conditions and investigate the integration of advanced technologies to further optimize defoliant applications. This study provides valuable insights for improving cotton production practices and ensuring consistent fiber quality. [ABSTRACT FROM AUTHOR]

Olive trees worldwide suffer from a number of devastating fungal diseases that affect production. One such serious disease is olive leaf spot caused by Venturia oleaginea. Recently, we applied magnesium hydroxide porous micron-scale particles (PMPs) on tomatoes and observed potent antimicrobial activity, reducing the fungal load of the treated phyllosphere. To assess the effectiveness of the compound on olive fungal disease, we applied it for two consecutive seasons. One particular olive tree exhibited extreme manifestations of fungal disease and was destined for removal. A single application of Mg(OH)2 PMP reversed all symptoms of the disease and eliminated the Venturia pathogen, curing the tree of disease. Venturia oleaginea appears to be exceptionally susceptible to treatment compared to other species in the fungal leaf community. The beneficial fungus Aureobasidium pullulans increased in relative abundance in all the sprayed trees. No toxicity and leaf loss were observed, and the compound retention exceeded 47 days. All trees sprayed showed drastic reductions in the total fungal load and compared favorably to the commercial copper compound. Spraying induced a moderate expression of key indicator genes associated with stress responses. No leaf chlorosis or shedding were observed. Overall, Mg(OH)2 PMP treatment appears to be a highly promising tool for combating plant fungal disease. [ABSTRACT FROM AUTHOR]

Faba bean is an important, protein-rich pulse crop grown worldwide, with increasing acreage in Canada in the last 50 years. Stemphylium blight can cause substantial yield losses due to defoliation of the plant. In 2022, high incidence levels of Stemphylium blight were observed in research plots at Rosthern and Melfort, SK. Based on morphological characteristics, DNA barcoding, and virulence testing, S. eturmiunum was confirmed as the causal pathogen of these Stemphylium blight lesions. This is the first report of S. eturmiunum infection causing Stemphylium blight on faba bean in Canada. Based on the severity of symptoms it can cause, S. eturmiunum has the potential to pose a serious threat to faba bean production. [ABSTRACT FROM AUTHOR]

Renowned for its leaf-spice attributes, kaffir lime has economic value that is worthy of intensifying amidst environmental threats, such as drought stress. This study aimed to analyze the morpho-physiological traits of kaffir lime in response to defoliation and drought stress. Kaffir lime was subjected to drought, defoliation, and a combination of both arranged in a randomised complete block design. Concerning morphology, defoliated lime produced a new flush that grows like a crown, while drought-treated plants displayed a bent pose with withered, edge-rolled, and drooping leaves. Higher leaf drop incidences were also noticed in drought-stressed plants. A combination of defoliation and drought stress produced severe flushing disruption by reducing 61% flush number, 77% flush fresh weight, and 74% flush dry weight, compared to undefoliated plants in normal irrigated conditions. Regardless of drought stress conditions, leaf production did not show significant differences among all defoliated plants. Defoliated plants maintained their photosynthetic rate and water use efficiency, leading to the absence of bent flush and rolling leaves as morphological markers of drought-treated plants. It is implied that defoliation can be a practical strategy for adapting kaffir lime in a drought environment. [ABSTRACT FROM AUTHOR]

The complex interplay between primary and secondary growth processes in trees holds paramount significance in unraveling the physiological connections within distinct tree tissues. In this study, we continuously monitored the intra-annual radial growth of Pinus koraiensis, Quercus mongolica, and Betula platyphylla in Changbai Mountain of northeast China using microcore techniques from April to September 2021. Additionally, we used existing leaf phenology models to simulate the seasonal variations of leaf area of three species. Our results revealed substantial difference in radial growth dynamics and leaf expansion patterns among the different wood species. Notably, a synchronization between leaf expansion and radial growth was observed in certain phases for pine and birch, with a significant positive correlation between the rates of leaf expansion and radial growth. Conversely, oak exhibited no synchrony between leaf development and radial growth. Temporal disparities between cambial phenology and leaf phenology were observed. Specifically, for pine, leaf unfolding occurred prior to the onset of wall-thickening, while leaf shedding took place after the cessation of lignification. Oak exhibited a delayed leaf unfolding compared to the initiation of secondary wall formation, and leaf shedding notably occurred later than the cessation of radial growth. In contrast, birch displayed an earlier leaf unfolding in comparison to the onset of radial growth, and the cessation of lignification was later than leaf shedding. These findings indicate the diversity in physiological mechanisms and survival strategies among different wood species. Our results suggest that radial growth in pine and birch appears to be heavily reliant on photosynthetic activity of leaves, while oak places greater emphasis on carbon storage, particularly during early growing season. The findings provide new insights into the complex mechanisms of tree growth and are critical for predicting future species suitability in temperate forests. [ABSTRACT FROM AUTHOR]

Farmers in Africa perceive the impact of fall armyworm (FAW) on maize to be significant, but field assessments have shown that yield losses are not significant enough to warrant pesticide interventions. This suggests that relationships between the crop stages, time, and duration of attack can affect the yield. Therefore, assessing the plant's recovery from damage using individual plants based on defoliation levels could guide whether and when pesticides should be applied. To study this, we selected 120 labeled maize plants corresponding to six levels of FAW defoliation, replicated 20 times, based on an initial damage rating. The rating scale ranged from 1 (no defoliation) to 5 (>75% defoliation) during four planting seasons. Plants with a rating scale of 1 were replicated and treated with a chemical insecticide to keep them undefoliated, and that served as a control. Damage severity was recorded weekly on all plants, starting from emergence until maturity, using the same damage rating scale. Results showed that damage severity varied significantly among different defoliation levels during all seasons. Higher levels of defoliation during dry seasons resulted in significant yield loss only for plants with damage levels 4 and 5, with damage severity ranging from 38.7% to 57.5%. These results indicate that FAW control is unnecessary in the rainy season. In contrast, pesticide interventions should be envisaged in seasons of erratic rainfall, with a significant defoliation threshold level of around 50%, occurring at 8 and 5 wk after planting weeks after planting, respectively for the early and late dry season. [ABSTRACT FROM AUTHOR]

Introduction: This study explores how elevated CO2 concentration may alter the source-sink dynamics in rice by providing additional carbon for photosynthesis, thereby affecting nutrient absorption and distribution. Methods: A free-air CO2 enrichment experiment was conducted on a japonica cultivar Wuyunjing 27 in 2017 and 2018 growing seasons. The plants were exposed to ambient and elevated CO2 level (increased by 200 μmol·mol-1) and two source-sink manipulation treatments (control with no leaf cutting and cutting off the top three leaves at heading). Results: The elevated CO2 significantly increased the above-ground biomass and the straw non-structural carbohydrate concentration by an average of 19.3% and 12.5%, respectively. Significant changes in the concentrations of N, S, Fe, and Zn in straw were noted under elevated CO2, with average decreases by 7.1, 7.2, 11.6, and 10.1%, respectively. The exposure to elevated CO2 significantly enhanced the elements accumulation, yet it had minimal impact on their distribution across different organs. When compared to intact rice, removing the top three leaves at heading reduced the above-ground biomass by 36.8% and the straw non-structural carbohydrate content by 44.8%. Leaf-cutting generally increased the concentration of elements in stem, leaf, and grain, likely due to a concentration effect from reduced biomass and carbohydrate accumulation. Leaf-cutting reduced element accumulation and shifted element allocation in rice organs. It increased the proportion of elements in stems while reduced their presence in leaves and grains. Discussion: Our study suggests that a dilution effect may cause a decrease in mineral elements concentrations under elevated CO2 because of the increase in biomass and carbohydrates. [ABSTRACT FROM AUTHOR]

Accurate inputs of surface roughness parameters are vital for estimating exchange of fluxes between surface and atmosphere, dispersion and transport of pollutants, wind erosion, and wind energy assessment studies, especially over heterogeneous and undulating surfaces. The roughness parameters are derived using observations from a 32 m high meteorological tower during 2016 to 2019. The site is located in the Deccan Plateau region at Shadnagar, India (17°01'59.7"N, 78°11'14.2"E) and experiences a tropical semi-arid climate. We employed multi-level low-frequency measurements (1-min) with a logarithmic wind profile method and single-level high-frequency measurements (20 Hz) with six alternative methods. The zero-plane displacement height () and aerodynamic roughness length for momentum () vary within the range 12.8 to 19.4 m and 0.05 to 0.42 m respectively, across eight wind-direction sectors. For the north-west and south-east sectors featuring prevailing winds, is about 16.2 m and 13.7 m respectively. The corresponding is about 0.15 m and 0.17 m respectively. Influence of seasonal changes in vegetation due to shedding of leaves is evident; and vary by 3 to 6% and 11 to 50%, respectively. Vertically extrapolated winds compared favourably against 100 m ERA5 reanalysis winds over the western sector, suggesting the optimal parameterization within ERA5 for cropland and shrub land covers which dominate these sectors. Our findings indicate that canopy height-based rule-of-thumb guidelines may not suitably estimate roughness parameters for the heterogeneous native land cover, dominated by shrubs and sparsely distributed trees, of the region. [ABSTRACT FROM AUTHOR]

City parks are of great importance to people living in cities, and the presence of trees in the parks increases the value of the parks. There are many types of trees that can be planted in parks. However, it is not possible for every tree to adapt to every natural environment. In addition, the initial investment costs of the trees, the characteristics that may affect the life cycle costs, and the expectations of managers and park users from the trees also affect this choice. All these criteria should be evaluated together, and the ideal selection should be made. Value Engineering is a method that can be applied to make the most appropriate choice by taking into account the wishes of all stakeholders. Value engineering (DM) can be defined as an organized effort to analyze product features, functions and material selections; is designed to solve problems and/or reduce costs while maintaining or improving performance and quality requirements; and performs essential functions at the required quality, reliability, and life-cycle cost. In this study firstly a value engineering team was formed. The value engineering team decided that the trees should be coniferous with the prerequisite that they can remain green without shedding their summer-winter leaves and determined which criteria the coniferous trees required to be located in the park should meet. The team members conducted value engineering after determining which trees met these criteria and were subsequently purchased. In this study, since an existing project and a new project are not compared, it does not include a result on how much the cost gain is. As a result, the team determined the most appropriate optimum cost solution with the value engineering method to meet all the criteria among the determined alternative tree species. [ABSTRACT FROM AUTHOR]

In the context of ongoing threats to forest ecosystems, this study investigates the temporal and spatial dynamics of Lymantria dispar defoliation intensity over a period of three years. We analysed the relationship between the insects' reproductive and feeding behaviours and forest stand characteristics, exploring the key factors that shape this behaviour. The results revealed a dynamic pattern, with a significant escalation of defoliation starting from the second year and peaking in the third. The analysis highlighted that, among several forest stand characteristics, woody species abundance and specific forest composition significantly influence population density and defoliation intensity. Sporadic outbreaks of the insects were associated with stand features, posing major challenges to forest health. These findings make a significant contribution to understanding the population dynamics of L. dispar and provide essential insights for forest managers in efficiently managing this defoliator. By highlighting the complex interactions between the insect and its environment, this study lays the groundwork for conservation and protection strategies for forest ecosystems. [ABSTRACT FROM AUTHOR]

Rachel Carson's warning of a silent spring directed attention to unwanted side effects of pesticide application. Though her work led to policies restricting insecticide use, various insecticides currently in use affect nontarget organisms and may contribute to population declines. The insecticide tebufenozide is used to control defoliating Lepidoptera in oak forests harboring rich insect faunas. Over 3 years, we tested the effect of its aerial application on bird populations with autonomous sound recorders in a large, replicated, full factorial field experiment during a spongy moth (Lymantria dispar) outbreak. The soundscape analysis combined automated aggregation of recordings into sound indices with species identification by experts. After pesticide application in the year of the outbreak, acoustic complexity in early summer was significantly reduced. The soundscape analysis showed that the reduction was not related to birds, but instead to the large reduction in caterpillar feeding and frass dropping. Effects on the vocal activity of birds were smaller than originally expected from a related study demonstrating tebufenozide's negative effect on bird breeding success. The legacy of the pesticide treatment, in terms of soundscape variation, was not present in the second year when the outbreak had ended. Our results showed a dimension of insecticide‐induced acoustic variation not immediately accessible to the human ear. It also illustrated how a multifaceted soundscape analysis can be used as a generic approach to quantify the impact of anthropogenic stressors in novel ways by providing an example of remote and continuous sound monitoring not possible in conventional field surveys. [ABSTRACT FROM AUTHOR]

ABSTRACT Plants in the understory experience climatic conditions affected by the overstory canopy that influence physiological and biochemical processes. Here, we investigate the relationships of leaf lipid molecular abundances to leaf water content, transmitted irradiance, and free‐air temperature (Tair) from deciduous angiosperm (Quercus buckleyi) and evergreen gymnosperm (Juniperus ashei) understory trees across an elevation gradient in a central Texas (USA) woodland. Monthly sampling from 04/2019 to 01/2020 revealed that long‐chain leaf waxes (≥ C27) accumulated with leaf water deficit over the growing season for both tree species. Higher transmitted light during the hottest, driest months was due to a decreased leaf area index (LAI) in the canopy as leaf shedding is a common drought response. Isoprenoids (sesqui‐, di‐terpenoids, phytosterols) in leaves changed by month with changing LAI and transmittance associated with monthly Tair changes. The chain length of n‐alkanols in Q. buckleyi shifted with seasonal LAI at different topographic positions. The unsaturation of fatty acids in both tree species decreased with increased seasonal Tair but showed topography sensitivity. Leaf‐level metabolites responded to understory microclimatic variables that were influenced by seasonality and topography. [ABSTRACT FROM AUTHOR]

ABSTRACT Extensive foliar shedding in monoculture soybeans post‐anthesis negatively impacts yield, whereas relay strip intercropping prolongs leaf area duration, enhancing productivity. However, little is known about the causes of leaf shedding in monoculture and its impact on physiological functions and plasticity of source and sink organs, we conducted a 4‐year field experiment and leaf‐removal simulations in relay intercropped soybeans. Results revealed that monoculture soybeans experienced severe self‐shading and defoliation, while relay intercropping maintained better light conditions, supporting higher leaf area, nodule numbers, and carbon allocation. Increasing leaf removal initially increased leaf area but eventually reduced it. Extensive leaf‐removal reduced Rubisco and sucrose phosphate synthase (SPS) activity, as well as sucrose, malate, ATP, and energy charge (EC) in nodules, revealing a trade‐off between leaf growth and nodule development. Moderate leaf‐removal (L30), however, balanced compensation and consumption, increasing total non‐structural carbohydrates (TNC) in roots and N and ureide in leaves and pods. Network analysis showed that L30 improved the synergies of functional traits in leaves and nodules, ultimately benefiting overall plant growth and nutrient accumulation in pods. This study elucidates a mechanism of foliar shedding and highlights how relay strip intercropping optimizes source‐sink coordination to enhance photosynthesis and nitrogen fixation. [ABSTRACT FROM AUTHOR]

Plant canopies are an important source of biological particles aerosolized into the atmosphere. Certain aerosolized microorganisms are able to freeze slightly supercooled cloud droplets and therefore affect mixed-phase cloud development. Still, spatiotemporal variability of such biological ice-nucleating particles (INPs) is currently poorly understood. Here, we study this variability between late summer and leaf shedding on the scale of individual leaves collected about fortnightly from four temperate broadleaf tree species (Fagus sylvatica, Juglans regia, Prunus avium and Tilia platyphyllos) on a hillside (Gempen, 650 m a.s.l. (metres above sea level)) and in a vertical canopy profile of one Fagus sylvatica (Hölstein, 550 m a.s.l.) in north-western Switzerland. The cumulative concentration of INPs active at ≥-10 °C (INPs−10) did not vary significantly between the investigated tree species but, as inferred from leaf mass per area and leaf carbon isotopic ratios, seemed to be lower on sun leaves as compared with shade leaves. Between August and mid-November, the median INP concentration increased from 4 to 38 INP−10 cm−2 of leaf area and was positively correlated with mean relative humidity throughout 24 h prior to sampling (Spearman's r=0.52 , p<0.0001 , n=64). In 53 of the total 64 samples collected at the Gempen site, differential INP spectra between -3 and -10 °C exhibited clearly discriminable patterns: in 53 % of the spectra, the number of additionally activated INPs increased persistently with each 1 °C decrease in temperature; the remaining spectra displayed significant peaks in differential INP concentration above -9 °C, most frequently in the temperature interval between -8 and -9 °C (21 %) and between -7 and -8 °C (17 %). Interestingly, the three most frequent patterns in differential INP spectra on leaves in Gempen were also prevalent in similar fractions in air samples with clearly discriminable patterns at the high-altitude Jungfraujoch site (3580 m a.s.l., Switzerland) collected during summer in the previous year. These findings corroborate the idea that a large fraction of the airborne biological INP population above the Alps during summer originates from plant surfaces. Which parameter or set of parameters could affect biological INP populations on both scales – upwind airsheds of high-altitude sites as well as individual leaves – is an intriguing question for further exploration. A first guess is that leaf wetness duration plays a role. [ABSTRACT FROM AUTHOR]

Question: Mammalian herbivory affects the structure and composition of plant communities, soil characteristics and intraspecific leaf traits. Understanding the effects of this type of herbivory is particularly relevant in grey dunes, a priority habitat type of the European Union Habitats Directive. Location: Sálvora island (NW Spain). Methods: Vegetation surveys and sampling were carried out in a coastal grey‐dune community, comparing the structure and composition of plant communities and soil characteristics in plots with herbivory exclusion and plots with herbivore activity, in autumn and spring. Changes in the specific leaf area (SLA), C/N ratio, δ13C and δ15N of two main plant species were also analysed. Results: The differentiation between treatments was low in autumn, in contrast to spring results, which demonstrated seasonal variation in the plant community and herbivore behaviour. Spring results showed lower above‐ground dry mass in plots with herbivory due to defoliation, but greater richness and diversity, indicating that intermediate levels of disturbance reduced competition from dominant species. Herbivory treatments were different in terms of species composition, highlighting the positive effects of herbivory on the development of the threatened species Linaria arenaria. Soil temperature and moisture content were higher in herbivory plots because of the suppression of vegetation cover and the effect of trampling, respectively. No differences were detected in the chemical composition of the soil or the SLA, although the variability of these traits was greater in herbivory plots, indicating spatial heterogeneity generated by the activity of herbivores. No differences between treatments were obtained for % C and δ13C, whereas herbivory plots showed lower values of N content and δ15N as an adaptive response to herbivory pressure at the leaf and root level. Conclusion: Our findings show that herbivory effects on plant communities vary by season — stronger in spring and weaker in autumn — emphasising the need for seasonal analysis and highlighting disturbance as a driver of spatial heterogeneity. [ABSTRACT FROM AUTHOR]

BACKGROUND: Transgenic Bt technology in soybean, with plants expressing Cry1Ac, has been adopted as an insect pest management tool. It was first adopted in large areas of South America and Asia in 2013. The risk of resistance in target pests to this technology demands insect resistance management (IRM) programs. In Brazil, a structured refuge (area of non‐Bt soybean) planted adjacent to the Bt soybean crop has been an important IRM recommendation, particularly for the primary lepidopteran defoliators Anticarsia gemmatalis (Lepidoptera: Erebidae) and Chrysodeixis includens (Lepidoptera: Noctuidae). The overall goal of this study was to validate IRM recommendations to Bt soybean. The objectives were to document the impact of soybean phenology, cultivar choice and non‐Bt soybean defoliation on moth oviposition. In addition, a mark‐release‐recapture study estimated the dispersal capacity of these species. Five field experiments per species were performed for 3 years. RESULTS: Our results revealed an increase in A. gemmatalis and C. includens oviposition, respectively, on Bt plants as a consequence of the difference in plant growth stage at the time of oviposition. Defoliation of non‐Bt plants significantly increased the oviposition preference of both moth species for Bt plants. The mark‐release‐recapture experiment indicated an average dispersal distance of ~300 m from the release point for A. gemmatalis, with maximum recapture at 1000 m. CONCLUSION: Overall, our findings emphasize the importance of planting synchronization of Bt soybean and the structured refuge. In addition, when operational aspects in large soybean areas challenge this recommendation, the priority should be for planting the refuge area first. This approach will minimize the impact of selective oviposition of A. gemmatalis and C. includens. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Traditional disease severity monitoring is subjective and inefficient. This study employs a Parrot multispectral sensor mounted on an unmanned aerial vehicle (UAV) to apply machine learning algorithms, such as random forest, for categorizing defoliation levels in R7-stage soybean plants. This research assesses the effectiveness of vegetation indices, spectral bands, and relative vegetation cover as input parameters, demonstrating that machine learning approaches combined with multispectral imagery can provide a more accurate and efficient assessment of Asian soybean rust in commercial soybean fields. The random forest algorithm exhibited satisfactory classification performance when compared to recent studies, achieving accuracy, precision, recall, F1-score, specificity, and AUC values of 0.94, 0.92, 0.92, 0.92, 0.97, and 0.97, respectively. The input variables identified as most important for the classification model were the WDRVI and MPRI indices, the red-edge and NIR bands, and relative vegetation cover, with the highest Gini importance index. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agriculture & Nature / Kahramanmaraş Sütçü İmam Üniversitesi Tarım & Doğa Dergisi is the property of Kahramanmaras Sutcu Imam Universitesi 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.)

Copyright of Glasnik Zastite Bilja is the property of Zadruzna Stampa D.D. 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.)

In the context of ongoing threats to forest ecosystems, this study investigates the temporal and spatial dynamics of Lymantria dispar defoliation intensity over a period of three years. We analysed the relationship between the insects' reproductive and feeding behaviours and forest stand characteristics, exploring the key factors that shape this behaviour. The results revealed a dynamic pattern, with a significant escalation of defoliation starting from the second year and peaking in the third. The analysis highlighted that, among several forest stand characteristics, woody species abundance and specific forest composition significantly influence population density and defoliation intensity. Sporadic outbreaks of the insects were associated with stand features, posing major challenges to forest health. These findings make a significant contribution to understanding the population dynamics of L. dispar and provide essential insights for forest managers in efficiently managing this defoliator. By highlighting the complex interactions between the insect and its environment, this study lays the groundwork for conservation and protection strategies for forest ecosystems.

Avicennia germinans, the black mangrove, has shifted its range limit northward, and increased in abundance in the Southeastern United States. In January 2018, a 3-day freeze event caused substantial defoliation of green leaves in A. germinans near its northernmost range limit in St. Augustine, FL. During their recovery, plants that lost their leaves grew similarly to plants fertilized with nitrogen, leading to the hypothesis that freeze-killed green leaves (frozen green) may have acted as a fertilizer. To assess the value of frozen green litter as a nutrient subsidy, we performed an experiment in which A. germinans seedlings were grown in sand with green, frozen green, senescent, and control leaf litter. We measured growth response in seedlings using the following criteria: total plant height, internode elongation, and plant biomass. All litter treatments stimulated growth in seedlings to a greater extent than that of controls. Seedlings treated with frozen green leaves were at least 5 cm taller and had 0.5 cm longer internodes than those treated with senescent leaves. Seedlings grown in the green leaf treatment were 8 cm taller, on average, and internodes were 0.12 cm longer than the senescent treatment. Biomass was 0.6–0.8 g greater in seedlings treated with green or frozen green litter than in the control treatments. We also conducted a leaching experiment to compare mass loss rates. Frozen and green leaves lost more mass in the leaching experiment than senescent leaves or controls. These results support the hypothesis that green litter that freezes can act as a nutrient source within the ecosystem and spur rapid recovery from freeze damage. [ABSTRACT FROM AUTHOR]

Abstract Defoliation is a primary agronomic traits, its variation depends on different plant species or cultivars. The present article assess the leaf morphological responses, oxidative metabolites and enzymatic activities at sheath base of sugarcane cultivars during defoliation stage of plant leaves. The mature leaf sheath of GT47 strongly wrapped to the stem, and no stem was exposed. The upper and lower edges of the immature fusing abscission zone were parallel, and slightly lower browning area (+ 3 to + 7 leaf position). The ROC22 cultivar was monitored highest leaf sheath-based cellulose and lignin content, followed by GT60 and GT47. Peroxidase activity was higher in leaf sheath base edge (ROC22) as compare to other cultivars. The malondialdehyde content was found highest in GT60, followed by ROC22, and GT47. The exo-β-1,4-glucanase/ cellobiohydrolase activity was found highest in the margin of GT47 than lateral and medial axis of ROC22 and GT60. The axis activity increased exponentially, and ROC22 gradually decreased from the periphery of the mid-axis and lower than GT47 and GT60 in the lateral and mid-axis of leaf. In conclusion, the mature leaves are easy to defoliate mainly loose leaf sheaths, large leaf sheath inclination angles, more deformation during the growth period of the abscission zone, early with large cracks, and slow browning process. Leaf sheaths with high fibre and lignin content showed significant hardness and thickness. The sugarcane cultivars showed positive correlation between peroxidase and malondialdehyde content with the browning process at the base of mature leaf sheaths.

An extensive discoloration (yellowing, browning), and defoliation (leaf loss) were observed in Slovak forests during the summer of 2022. These phenomena are attributed to the combination of very low atmospheric precipitation and extremely high air temperatures from June to early August. In this study, the deterioration of forest health was analysed by comparing the image classification of Sentinel-2 satellite data from the year of intense drought occur-rence, 2022, with that from a referenced year without drought occurrence, 2020. The results indicated that in 2022, the proportion of heavily damaged stands with defoliation exceeding 50% doubled, reaching 19.3% (417,000 ha), and an area of 223,000 ha experienced an increase in defoliation by 30% or more. The damage exhibited an uneven spatial distribution, with the most significant impact observed in the western and southern parts of central Slovakia, as well as partially in the southern part of eastern Slovakia. Further GIS analyses revealed that forests growing on slopes with southern aspects suffered more severe damage than with northern exposures. However, the difference between the most damaged forests with south-southeast exposure (12.2%) and the least damaged ones with north-northwest exposure (8.2%) was only 4%. The level of damage gradually decreased with increasing altitude. Nevertheless, compared to previous studies, the damage was significantly manifested even in the fourth forest vegetation zone, up to an elevation of approximately 800 m. Regarding soil texture, which influences the water regime, the damage gradually decreased with decreasing sand content, ranging from sandy soils (17.5%) to clayey soils (6.6%).

Successful establishment of desired species during restoration is challenging in drylands. Much research has focused on the importance of the critical life stages such as germination and emergence, but factors influencing survival through the seedling stages of perennial grasses may be equally important. We asked whether seedling defoliation by insects and/or mammals could cause restoration failure. We quantified the degree of defoliation on seedlings of common perennial grass species at 46 restoration sites throughout Oregon, Idaho, and Nevada, and calculated survival probabilities during the first growing season after planting. At each site, we excluded small mammals and insects for 6 weeks and compared defoliation and survival probabilities with seedlings in controls without exclusions. Seedlings were classified as either: large perennial grasses (LPG), primarily from the Triticeae tribe, or Bluegrasses (Poa spp.). Defoliation of LPG reduced seedling survival, but the effect was small compared to the influence of meteorological variables, such as precipitation and temperature. Based on bite patterns, most defoliation resulted from insects. Only a small percentage of vegetation was removed (36% of individuals were defoliated, mean = 13.2% vegetation removal). Defoliation of bluegrasses was less common than that of LPG seedlings, with only 16% experiencing defoliation, primarily from insects (mean = 4.3% vegetation removal). Some defoliation did occur within the exclusion treatments, but the effect of defoliation on seedling survival did not appear to interact with treatment. Based on the results of this study, seedling herbivory is unlikely to be a major factor in restoration failure in the Northern Great Basin. [ABSTRACT FROM AUTHOR]

Plant reproduction is often inhibited by herbivorous leaf damage, which affects the resource pool allocated for reproduction. Rhododendron kaempferi var. kaempferi is a semi‐evergreen shrub widely distributed in Japan, and its leaves are occasionally damaged by sawfly larvae (Arge similis). This species is partially self‐compatible, but its selfed seedlings suffer from inbreeding depression. Our study aimed to clarify (1) the magnitude of herbivorous damage under natural conditions, (2) the effects of foliage damage on seed number and mass, and (3) the possibility of selective abortion of selfed seeds to maintain outcrossed seed production under resource limitation. In the 2022 survey, 2 of the 20 ramets observed were collectively parasitized by sawfly larvae, and the most damaged ramet had a 59.6% foliage loss. In contrast, the herbivorous damage in 2023 was consistently low throughout the growing season, averaging a 3.2% loss. Leaf excision reduced the seed number per fruit (i.e., low seed‐set rate) but did not affect the individual seed mass. The outcrossing rate of the excision treatment (81.7%) was significantly higher than that of the control (72.0%). The values of seed‐set rate × outcrossing rate were 0.172 for the excision treatment and 0.171 for the control, nearly equal. Our results indicated that (1) sawfly larvae damage was concentrated on a few specific plants, (2) intense foliage damage reduced seed number but not seed mass, and (3) R. kaempferi mitigated the decline in outcrossed seed production by the abortion of selfed seeds when leaves were intensively damaged. [ABSTRACT FROM AUTHOR]

In this study, the effects of supplemental or night interruptional blue light (S-BL or NI-BL) positioning on morphological growth, photoperiodic flowering, and expression of floral genes in Chrysanthemum morifolium were investigated. Blue light-emitting diodes (LEDs) at an intensity of 30 μmol·m−2·s−1 photosynthetic photon flux density (PPFD) were used for 4 h either (1) to supplement the white LEDs at the end of the 10 h short-day (SD10 + S-BL4) and 13 h long-day conditions (LD13 + S-BL4), or (2) to provide night interruption in the SD10 (SD10 + NI-BL4) and LD13 (LD13 + NI-BL4). The S-BL4 or NI-BL4 was positioned to illuminate either the shoot tip, the youngest leaf (vigorously growing the third leaf from the shoot tip), or the old leaf (the third leaf from the stem base). In the text, they will be denoted as follows: SD10 + S-BL4-S, -Y, or -O; SD10 + NI-BL4-S, -Y, or -O; LD13 + S-BL4-S, -Y, or -O; LD13 + NI-BL4-S, -Y, or -O. Normally, the LD13 conditions enhanced more vegetative growth than the SD10 periods. The growth of leaves, stems, and branches strongly responded to the S-BL4 or NI-BL4 when it was targeted onto the shoot tip, followed by the youngest leaf. The SD10 + S-BL4 or +NI-BL4 on the old leaf obviously suppressed plant extension growth, resulting in the smallest plant height. Under LD13 conditions, the flowering-related traits were significantly affected when the S-BL4 or NI-BL4 was shed onto the youngest leaf. However, these differences do not exist in the SD10 environments. At the harvest stage, other than the non-flowered LD13 treatment, the LD13 + S-BL4 irradiating the youngest leaf induced the most flowers, followed by the shoot tip and old leaf. Moreover, LD13 + NI-BL4 resulted in the latest flowering, especially when applied to the shoot tip and old leaf. However, the SD10 + S-BL4 or + NI-BL4 irradiated the shoot tip, youngest leaf, or old leaf all significantly earlier and increased flowering compared to the SD10 treatment. Overall: (1) Generally, vegetative growth was more sensitive to photoperiod rather than lighting position, while, during the same photoperiod, the promotion of growth was stronger when the light position of S-BL4 or NI-BL4 was applied to the shoot tip or the youngest leaf. (2) The photoperiodic flowering of these short-day plants (SDPs) comprehensively responded to the photoperiod combined with blue light positioning. Peculiarly, when they were exposed to the LD13 flowering-inhibited environments, the S-BL4 or NI-BL4 shed onto the leaves, especially the youngest leaves, significantly affecting flowering. [ABSTRACT FROM AUTHOR]

Cirina butyrospermi Vuillet (Lepidoptera: Attacidae) is an insect whose larvae feed only on shea leaves [Vitellaria paradoxa C.F. Gaertn. (Sapotaceae)]. The last larval stages (L4 and L5) of this insect are harvested and used as food and in a lesser extent, as feed in Southwest of Burkina Faso. However, the distribution and density of C. butyrospermi edible caterpillar have not yet been investigated in Southwest of Burkina Faso. The objective of this work is to evaluate the density and damage of shea caterpillars in the shea parklands located along the Koumbia-Dano environmental and ethnical transect, during three consecutive shea caterpillar seasons (2020, 2021 and 2022). The density of individuals/square meter of shea leaves of each of the five larval stages, including dead larvae, was evaluated on the sampled shea trees. The infestation rate and the severity of defoliation were also investigated. The density of edible larval stages (L4 and L5) ranged from 2.95 ± 3.35 to 29.50 ± 25.49 individuals/m2 of shea leaves according to the study sites and the year. The percentage of shea tree infested with caterpillars and the attack severity varied from 35.57 to 57.50% and from 8.71 to 25.50%, respectively, depending on the study sites and the year. Further investigation is necessary to determine the cause of the larvae mortality and the reasons for the heterogeneous distribution of C. butyrospermi along the transect. [ABSTRACT FROM AUTHOR]

The effects of mechanical defoliation and pinching (1 cm tip cutting) on Buxus plant growth, nutrient mobilization, and root architecture were determined. When 100% defoliation was applied, the highest increase rates of 80.3% in shoots and 88% in leaves were observed compared to the control group. In contrast, the overall effects of defoliation and pinching were negative, with 100% defoliation having the most negative effects. The chlorophyll content of the newly formed young leaves was also 50% lower with 100% defoliation. Leaves and root nutrient mobilization changed significantly, depending on the effects of defoliation and pinching. Apart from a very small increase in root length and number of forks, the effects of the treatments were negative, with 100% defoliation having the greatest negative effect on root development. Most affected was the number of crossings, which was 78% lower than in the control. In addition, machine learning (ML) algorithms were used in the study, including multilayer perceptron, J48, PART, and logistic regression. The input variables were evaluated to model and predict the root features. The performance values of the ML algorithms were noted in the following order: Logistic Regression> PART> J48> MultilayerPerceptron. As the severity of defoliation increased, the losses of the plant also increased. However, boxwood has mechanisms to compensate for these losses even when it suffers complete defoliation. [ABSTRACT FROM AUTHOR]

Defoliation and tree species determine growth during spruce budworm outbreaks, with site showing inconsistent effects. We determined effects of artificial defoliation treatments (0%, 50%, 100%, 100%+bud) for 3 years on volume increment of 240 balsam fir, black spruce, and white spruce trees, initially 7–10 years old and 2.3–4.1 m tall, on four soil drainage/richness classes. Current annual increment was significantly affected by species × site and site × defoliation interactions, with DBH as covariate. Specific volume increment (SVI) was significantly affected by a species × site × defoliation treatment interaction. Combining species and sites, volume reductions after 3 years were 21%–28%, 43%–51%, and 55%–66% for 50% defoliation, 100% defoliation, and 100%+bud. SVI was negatively, linearly related to cumulative defoliation. Marginal r2 and conditional r2 showed that 64% of variance of SVI was explained by site, species, cumulative defoliation, and DBH, but 90% was explained by fixed and random variables. After 3 years of defoliation, SVI of white spruce was 21%–23% greater than balsam fir and black spruce, and SVI on rich was 55%–79% greater than on poor sites. Cumulative defoliation was a good predictor of growth, and soil richness had a stronger effect on growth after defoliation than in previous studies. [ABSTRACT FROM AUTHOR]

Defoliation by eastern spruce budworm is one of the most important natural disturbances in Canadian boreal and hemi‐boreal forests with annual area affected surpassing that of fire and harvest combined, and its impacts are projected to increase in frequency, severity, and range under future climate scenarios. Deciding on an active management strategy to control outbreaks and minimize broader economic, ecological, and social impacts is becoming increasingly important. These strategies differ in the degree to which defoliation is suppressed, but little is known about the downstream consequences of defoliation and, thus, the implications of management. Given the disproportionate role of headwater streams and their microbiomes on net riverine productivity across forested landscapes, we investigated the effects of defoliation by spruce budworm on headwater stream habitat and microbiome structure and function to inform management decisions. We experimentally manipulated a gradient of defoliation among 12 watersheds during a spruce budworm outbreak in the Gaspésie Peninsula, Québec, Canada. From May through October of 2019–2021, stream habitat (flow rates, dissolved organic matter [DOM], water chemistry, and nutrients), algal biomass, and water temperatures were assessed. Bacterial and fungal biofilm communities were examined by incubating six leaf packs for five weeks (mid‐August to late September) in one stream reach per watershed. Microbiome community structure was determined using metabarcoding of 16S and ITS rRNA genes, and community functions were examined using extracellular enzyme assays, leaf litter decomposition rates, and taxonomic functional assignments. We found that cumulative defoliation was correlated with increased streamflow rates and temperatures, and more aromatic DOM (measured as specific ultraviolet absorbance at 254 nm), but was not correlated to nutrient concentrations. Cumulative defoliation was also associated with altered microbial community composition, an increase in carbohydrate biosynthesis, and a reduction in aromatic compound degradation, suggesting that microbes are shifting to the preferential use of simple carbohydrates rather than more complex aromatic compounds. These results demonstrate that high levels of defoliation can affect headwater stream microbiomes to the point of altering stream ecosystem productivity and carbon cycling potential, highlighting the importance of incorporating broader ecological processes into spruce budworm management decisions. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis Editorial Office 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.)

Fire damage can significantly impact fruit productivity in orchards. However, the effects of nonlethal fire injuries on the reproductive development of apple trees remain poorly understood. To investigate these effects, we implemented three treatments: trunk girdling to simulate fire injury to xylem, defoliation of a third of the canopy (simulated crown fire injury), and a combined treatment (simulated surface fire injury), alongside a control. The experiment was conducted during the 2021–22 growing season using a randomised block design with four biological replicate plots. Girdling was less effective than crown and surface fire treatments in influencing fruit composition during the current growing season, and flowering and fruiting in the following season. The crown and surface fire treatments induced localised detrimental effects on fruit sugar and titratable acidity while stimulating peel blush. Additionally, these treatments led to reduced starch reserves by harvest, which likely disrupted subsequent flowering and crop load near the previously defoliated sections of the canopy. When surface fires damage leaves near the base of the canopy in addition to the trunk, fruit production in the lower part of the canopy is more likely to be compromised in the following season. Crown fires, which cause leaf loss near the apex of the canopy, appear to be particularly detrimental to tree productivity, as the top defoliation treatment impaired carbohydrate reserves in shoot terminals and roots. In conclusion, fire-induced loss of leaf area during fruit growth alters fruit composition in the current growing season and may lead to lower yields in the subsequent season. [ABSTRACT FROM AUTHOR]

Selecting seedlings of varying sizes and effectively managing root pruning are key challenges in transplantation. However, the effects of seedling size and root pruning on transplantation outcomes are not fully understood. This study classified one-year-old Populus 'Beilinxiongzhu-01' seedlings into three size categories based on height: large (308.75 ± 9.66 cm), medium (238.00 ± 7.71 cm), and small (138.92 ± 7.18 cm). In early March of the subsequent year, root pruning was applied with varying intensities based on root collar diameter: low (15 times), medium (7.5 times), and high (3.75 times). A control group without pruning was also included. Over the year, key phenological and morphological traits were monitored. The results showed that (1) root pruning significantly impacted the phenology of seedlings, accelerating root emergence, delaying early leaf phenology, increasing the dieback rate, and postponing end-of-season defoliation. Mortality and the rapid growth phase were not significantly affected. Larger seedlings exhibited earlier end-of-season defoliation and higher dieback rates early in the growing season, while smaller seedlings advanced in early leaf development. (2) Except under low or no pruning, root pruning reduced seedling height (H), diameter at breast height (DBH), and root collar diameter (RCD). However, across all treatments, these indicators remained higher in larger seedlings compared to smaller ones. Under medium- and high-intensity pruning, smaller seedlings exhibited higher relative growth rates and larger leaf areas than larger seedlings, with the reduction in these variables becoming more pronounced as seedlings increased in size. Notably, only larger seedlings demonstrated a reduction in maximum growth rate, suggesting greater vulnerability to root pruning. In summary, root pruning induced significant phenological and morphological differences across seedling sizes. While smaller seedlings showed some response to pruning, larger seedlings experienced more pronounced phenological disruptions and growth inhibition. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effects of different potassium (K) fertilization levels and defoliation intensities on performance of "BRS Zuri" guineagrass Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L Jacobs (syn. Panicum maximum Jacq.). Treatments were the factorial arrangement of three K fertilization levels: 0 (control), 40, 80 kg K2O/ha/harvest) and two defoliation intensities (10‐ and 20‐cm stubble heights), distributed in a completely randomized design with five replications. The experiment was conducted in Araguaina, TO, Brazil, from October to January, 2020–2021 and 2021–2022. Plots were harvested four times per year with 21‐day regrowth interval. The 40 and 80 kg K2O/ha/harvest fertilization levels had greater HA than the control (5490 vs. 3,440 kg DM/ha, respectively). There was a K fertilization level × stubble height interaction on tiller population. There was greater tiller population at 20‐ than 10‐cm stubble height at 40 kg K2O/ha/harvest; however, no effect of stubble height was detected at 0 and 80 kg K2O/ha/harvest. Plots fertilized with 80 kg K2O/ha/harvest had greater tiller population than 40 kg K2O/ha/harvest, which was greater than control. Forage harvested at 10 cm had greater crude protein (CP) than 20‐cm stubble height (mean = 11.4% vs. 10.8%). Tissue K concentration increased from control to 40 kg K2O/ha/harvest, but there was no difference between 40 and 80 kg K2O/ha/harvest (mean = 1.1% vs. 3.5%). The combination of 40 kg K2O/ha/harvest and 20‐cm stubble height may be a desirable management strategy to promote Zuri guineagrass productivity in tropical regions. [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.)

Plantago lanceolata L. (plantain) increases herbage dry matter (DM) production and quality during warm and dry conditions due to its deep roots and drought tolerance and reduces nitrogen losses in grazing systems compared to traditional pastures. However, plantain density usually declines after the third growing season, mainly due to defoliation management. The effects of defoliation frequency and intensity on water-soluble carbohydrate (WSC) reserves and below-ground plant responses need further research to optimize grazing strategies for improved productivity and sustainability of grazing systems. Our study investigated the effects of defoliation frequencies (15, 25, and 35 cm of extended leaf length, ELL) and intensities (5 and 8 cm of residual heights) on morphological traits and WSC concentrations in plantain biomass under controlled environmental conditions. Defoliation frequency significantly influenced morphological and chemical characteristics and biomass distribution more than residual height. Less frequent defoliations promoted above-ground herbage DM production, reproductive stems, and root biomass. Root architecture showed adaptations in response to defoliation frequency, optimizing resource acquisition efficiency. Frequent defoliation reduced high molecular weight WSC concentrations in leaves, affecting regrowth capacity and DM mass. A defoliation frequency of 25 cm ELL (~15 days) balances herbage production and root development, promoting long-term pasture sustainability. [ABSTRACT FROM AUTHOR]

Growing season freeze events pose a threat to quaking aspen (Populus tremuloides Michx.), leading to canopy defoliation, reduced vigor, and increased mortality, especially for declining montane populations western North America. Detecting the spatial distribution and progression of this damage is challenging due to limited in situ observations in this region. This study represents the first attempt to comprehensively resolve the spatial extent of freeze-induced aspen canopy damage in southern Utah using multispectral remote sensing data. We developed an approach to detect the spatial and temporal dynamics of freeze-damaged aspen stands, focusing on a freeze event from 8–9 June 2020 in southern Utah. By integrating medium- (~250 to 500 m) and high-resolution (~10 m) satellite data, we employed the Normalized Difference Vegetation Index (NDVI) to compare post-freeze conditions with historical norms and pre-freeze conditions. Our analysis revealed NDVI reductions of 0.10 to 0.40 from pre-freeze values and a second flush recovery. We introduced a pixel-based method to evaluate freeze vulnerability, establishing a strong correlation (R values 0.78 to 0.82) between the onset of the first flush (NDVI > 0.50) and the accumulation of 100 growing degree days (GDD). These methods support the potential for retrospective assessments, proactive forest monitoring, and forecasting future risks. [ABSTRACT FROM AUTHOR]

Traditional pastures in temperate regions face limitations such as reduced growth and nutritional quality during the summer season. Plantain (P. lanceolata L.) offers advantages like increased yield and decreased nitrogen losses from grazing ruminants. Effective grazing management is essential for pasture health, and defoliation frequency and intensity play a pivotal role. This study aimed to evaluate plantain's regrowth, yield, and morpho-physiological and chemical responses under different defoliation frequencies and intensities, with the goal of enhancing its management in pastures. The study was conducted in pots within a controlled-environment growth chamber, examining the impact of three defoliation frequencies (based on extended leaf length: 15, 25 and 35 cm) and two defoliation intensities (5 and 8 cm of residual heights) with four replicates (24 pots as experimental units). The variables of interest were morphological characteristics, dry matter (DM) accumulation, herbage chemical composition, growth rate traits, and photosynthetic parameters. Defoliation frequency affected plantain's growth and nutritional composition. More frequent cuts (15 cm) resulted in lower DM yield per cut and lower stem content, while less frequent cuts (35 cm) produced higher values. Defoliation intensity influenced the proportion of leaves and stems in the total DM, with 5 cm cuts favoring leaves. Nutrient content was also affected by defoliation frequency, with less frequent cuts (35 cm) showing lower crude protein concentration and metabolizable energy content but higher neutral detergent fiber and water-soluble carbohydrate concentration. Plantain's growth rate variables were mainly influenced by defoliation frequency, with less frequent cuts promoting faster leaf appearance and growth of new leaves. The basal fluorescence variables and chlorophyll content were affected by cutting frequency, being highest when cut less frequently (35 cm), while no differences were found in the actual quantum efficiency among different defoliation frequencies and intensities. The fraction of light dedicated to non-photochemical quenching was highest when cut less frequently and more intensively. Overall, defoliation at 25 cm of extended leaf length balanced plantain forage quality and regrowth capacity. [ABSTRACT FROM AUTHOR]

Maize is one of the most important grains in the world. The leaves play an important role in providing grain reserves in cereals by performing photosynthesis. The leaf is known as the source and the seed is known as the sink. Removing part of the leaf can decrease the amount of photosynthetic material produced by the plant. A C4 plant, maize has been widely cultivated as a summer plant in western of Iran in recent years. Utilizing maize for both grain and forage can reduce the amount of the woody residues left by this plant in the soil while providing part of the forage for livestock. Field and laboratory experiments were conducted to investigate the effect of defoliation and nitrogen on seed yield and germination characteristics of seeds derived from the maternal plant. Defoliation intensities (removing none, half of the leaves, or all of the leaves per plant) and nitrogen rates (zero and 100 kg ha-1) were among the variables examined. Nitrogen and defoliation as two source manipulations were used. The results demonstrated a significant decrease in the number of seeds per ear row and column, cob length and weight, and seed yield upon complete defoliation during the tasselling stage. Germination features of generated seeds were also affected by the maternal plant environment. Under removal of all leaves per plant, seed germination percentage, seed vigor, and seedling weight were reduced. Harvesting of the half-green leaves prior to the ripening of the seeds did not result in a decrease in seed yield or germination characteristics of the generated seeds. Nitrogen had less application of an impact on the analyzed maize features than defoliation. In conclusion, half of the green leaves in maize can be harvested before seed maturity without reducing seed yield and seed germination. [ABSTRACT FROM AUTHOR]

In order to study the nutrient cycling process of Fraxinus velutina plantation, the nutrient resorption of N, P, K, Ca and Mg in male plants of F. velutina with different diameter classes was systematically analyzed. The result showed that N, P and K in leaves were obviously resorbed by other tissues before abscission, while Ca and Mg were further enriched in the leaves. The nutrient resorption efficiencies of N in F. velutina plants were mostly in the range of 40%-60%, the nutrient resorption efficiencies of Ca were mainly distributed between (–10%) and (–40%), however, the range of nutrient resorption efficiencies of other elements were relatively dispersed. Compared with the plants of larger diameter class, the plants of small diameter class of F. velutina had higher N resorption efficiencies and lower K resorption efficiencies. There was a highly significant positive correlation between leaf N and P nutrient resorption efficiency of F. velutina. During the defoliation stage, the organic N and P fractions of senescent leaves were hydrolyzed into amino acids and inorganic P respectively and then transported out, and these two physiological processes were simultaneous and closely related, and this was also the main reason why N and P resorption efficiencies were closely related. The nutrient resorption efficiency of Ca and Mg also showed a significant positive correlation. Ca and Mg were important structural elements in cell wall and chlorophyll molecule respectively, and these two elements often accumulated continuously in the senescent leaves, which was called "negative resorption", indicating that the transfer processes of these two elements in plants were similar and correlated. The N/P ratios of the fresh leaves of the young F. velutina trees were more than 16, while when the diameter of F. velutina was more than 10 cm, the N/P ratios were mostly less than 14, which indicated that with the increase of forest age, the P limitation in the plantation gradually changed into N limitation. The above results indicate that the application amount of nitrogen fertilizer should be gradually increased with the growth of forest age. The above research results can provide a theoretical reference for further understanding the nutrient cycle process of F. velutina. [ABSTRACT FROM AUTHOR]

There is a close relationship between stem and leaf biological characteristics of mature broccoli plants and defoliation technology. Morphological parameters such as the spread degree and diameter of cauliflower stem and leaf and the connection performance of cauliflower stem and leaf were studied. These experiments are helpful to the research of defoliation devices and methods for large-scale manual transportation lines. In this paper, according to the damage forms that may be suffered in the separation process of mature broccoli stems and leaves, "sunny" broccoli varieties were selected. Firstly, the mechanical properties of mature broccoli stems were obtained through different loading methods such as stretching, compression, shearing and bending. Secondly, the stress relaxation characteristics of broccoli were analyzed by static compression of broccoli flower balls. Finally, the separation method of broccoli stems and leaves was simulated by ANSYS. The simulation results showed that shear fracture was more suitable for stem and leaf separation of broccoli than tensile fracture. Then, aiming at the separation of stems and leaves of broccoli, an artificial broccoli assembly line was proposed to ensure the efficiency of leaf removal through man–machine cooperation. The dynamic characteristics of the belt of broccoli leaf removal line were studied to ensure the efficient and stable operation of the conveyor system of broccoli artificial leaf removal line. [ABSTRACT FROM AUTHOR]

The mutual influence of components in an aqueous system consisting of ammonium sulfate and magnesium chlorate defoliant was studied in a wide concentration range at a temperature of -27.0 to 4.5°C. On the state diagram of the system, the fields of crystallization of ice, magnesium chlorate hexahydrate, ammonium sulfate, and the compound (NH4)2SO4 · 2NH4CIO3 · 2MgSO4 · H2O are delimited, which was identified and characterized by chemical, X-ray phase, thermal, and IR spectroscopic methods of analysis. [ABSTRACT FROM AUTHOR]

Denphal-type Dendrobium is the famous cut and potted flower in the world, and most cultivated in tropical and subtropical regions. However, it often suffers from cold in winter in subtropical regions. To verify the physiological response of Denphal-type Dendrobium under low temperature in this study, the mature and young plantlets of Dendrobium Udomsri Beauty were treated under 15, 10, and 5 °C, respectively. And then the electrical conductivity (EC), soluble protein, soluble sugar, free proline, malondialdehyde (MDA), chlorophyll content, and the rate of defoliation after regrowth were measured. The results showed that both mature plant and young seedlings of Dendrobium Udomsri Beauty, the EC, soluble protein, soluble sugar, free proline, MDA content, and defoliation rate were increased with the decrease of treatment temperature and the extension of treatment times. The content of chlorophyll decreased gradually with the decrease of treatment temperature and the extension of treatment times. The correlation analysis showed that soluble sugar, free proline, MDA, chlorophyll content, and defoliation rate were significantly correlated with the semi-lethal temperature. It is indicated that the content of free proline, MDA, chlorophyll, and defoliation rate could be used as the effective indexes for the comprehensive assessment of cold tolerance of Dendrobium Udomsri Beauty. [ABSTRACT FROM AUTHOR]

Ungulate herbivores shape grassland plant communities at multiple scales, ultimately affecting ecosystem function. However, ungulates have complex effects on grasslands, including defoliation, trampling, excreta return and their interactions. Moreover, the effects of ungulate density on grasslands are regulated by these three mechanisms. Nevertheless, how these three mechanisms affect biodiversity at multiple scales and community assembly remains poorly understood.Here, we conducted a 4‐year novel field experiment to disentangle the effects of defoliation, trampling, and excreta return by ungulates on plant community assembly in a temperate grassland in Inner Mongolia, China. This experiment set two different scenarios: moderate ungulate density (Moderate, characterised by selective defoliation and moderate trampling) and high ungulate density (Intense, characterised by non‐selective defoliation and heavy trampling), including different combinations of defoliation, trampling and excreta return in each scenario.We found that defoliation and trampling increased stochasticity in community assembly and promoted alpha and beta diversity under both scenarios. Specifically, defoliation promoted the coexistence of species with multiple resource acquisition strategies (higher functional trait diversity) by reducing interspecific competition; trampling tended to facilitate random species colonisation. Conversely, excreta return favoured grasses, promoting deterministic assembly and impacting species coexistence. Notably, selective defoliation in the Moderate scenario led to a dominance of stochastic processes during community assembly, whereas non‐selective defoliation still did not change the dominance of deterministic processes. Further, communities subject to selective defoliation were insensitive to changes in soil properties caused by trampling and excreta return, maintaining a high‐level beta diversity and the stochastic of community assembly.Synthesis: Our study provides important insights into the mechanisms by which ungulate herbivores influence plant community assembly, suggesting that defoliation and trampling have the potential to drive stochastic processes, while excreta return plays the opposite role. Our study also suggests that selective foraging by ungulates acts as stronger stochastic forces during community assembly compared to non‐selective defoliation. These results imply that considering ungulate feeding preferences and foraging behaviour in grassland management will help prevent biodiversity loss and biotic homogenisation. [ABSTRACT FROM AUTHOR]

Cat's claw creeper (Dolichandra unguis‐cati), native to tropical South America, is a major invasive species and a target for biological control in Australia, South Africa and some South Pacific Island countries. Native range surveys in Argentina, Brazil, Paraguay and Venezuela have identified eight insects and four fungal pathogens as potential agents. Five leaf‐feeding insects a tortoise beetle Charidotis auroguttata, two tingids Carvalhotingis visenda and C. hollandi, a leaf‐tying moth Hypocosmia pyrochroma and a leaf‐mining beetle Hedwigiella jureceki, have been tested and all were released in South Africa. Four of these have become established but are not widespread and cause only limited damage. In Australia, only three of these, C. visenda, H. pyrochroma and H. jureceki were released, while C. auroguttata was not approved due to perceived non‐target risks. All agents have become widely established, except for H. pyrochroma which is restricted to riparian corridors in southeast Queensland. In South Africa, an accidentally introduced leaf‐spot pathogen, Neoramulariopsis unguis‐cati, causes necrotic lesions and premature abscission of leaves in cat's claw creeper infestations, resulting in widespread defoliation. Based on its impact and field‐host specificity in its native range and in South Africa, the pathogen has been prioritised for evaluation as a potential additional agent in Australia. The current priority is to seek approval for the introduction of this leaf‐spot pathogen into Australia. Future research should focus on the gall‐inducing rust Uropyxis rickiana and the seed‐feeding weevil Apteromechus notatus as prospective agents. [ABSTRACT FROM AUTHOR]

Hymenoscyphus fraxineus causes ash dieback in Europe. It overwinters on ash leaf residue (rachis) within the forest litter. In late spring, the fungus produces apothecia on the rachises and releases ascospores to infect leaves. Previous studies reported that H. fraxineus was able to produce apothecia on the rachis for 5 years after the leaf infection under artificial conditions. However, ash litter is known to decompose rapidly in situ. We therefore monitored the decomposition kinetics of ash leaf debris and the persistence of the pathogen, as well as its ability to produce apothecia in the forest litter. For this, leaves shed in autumn in stands affected by ash dieback were placed in mesh bags and left in the forest litter for 6, 18 and 30 months. At each sampling period, litter mass loss and level of colonization of the rachises by H. fraxineus were measured, as was the pathogen's ability to produce apothecia on them. Despite high fragmentation, about 14% of the rachis dry weight remained in the mesh bags after 30 months, and the pathogen retained the ability to produce apothecia on these rachises. A simulation estimating the age composition of the colonized rachises present in the litter during the fruiting period was developed from these results. It shows that the persistence of H. fraxineus in old rachises of the litter represents a reservoir of inoculum that could compensate for poor colonization of autumn leaves and revive local outbreaks after years of unfavourable weather for the development of the pathogen. [ABSTRACT FROM AUTHOR]

Shoot branches grow from axillary buds and play a crucial role in shaping shoot architecture and determining crop yield. Shade signals inactivate phytochrome B (phyB) and induce bud dormancy, thereby inhibiting shoot branching. Prior transcriptome profiling of axillary bud dormancy in a phyB‐deficient mutant (58M, phyB‐1) and bud outgrowth in wild‐type (100M, PHYB) sorghum genotypes identified differential expression of genes associated with flowering, plant hormones, and sugars, including SbCN2, SbNCED3, SbCKX1, SbACO1, SbGA2ox1, and SbCwINVs. This study examined the expression of these genes during bud dormancy induced by shade and defoliation in 100M sorghum. The aim was to elucidate the molecular mechanisms activated by shade in axillary buds by comparing them with those activated by defoliation. The expression of marker genes for sugar levels suggests shade and defoliation reduce the sugar supply to the buds and induce bud dormancy. Intriguingly, both shade signals and defoliation downregulated SbNCED3, suggesting that ABA might not play a role in promoting axillary bud dormancy in sorghum. Whereas the cytokinin (CK) degrading gene SbCKX1 was upregulated solely by shade signals in the buds, the CK inducible genes SbCGA1 and SbCwINVs were downregulated during both shade‐ and defoliation‐induced bud dormancy. This indicates a decrease in CK levels in the dormant buds. Shade signals dramatically upregulated SbCN2, an ortholog of the Arabidopsis TFL1 known for inhibiting flowering, whereas defoliation did not increase SbCN2 expression in the buds. Removing shade temporarily downregulated SbCN2 in dormant buds, further indicating its expression is not always correlated with bud dormancy. Because shade signals also trigger a systemic early flowering signal, SbCN2 might be activated to protect the buds from transitioning to flowering before growing into branches. In conclusion, this study demonstrates that shade signals activate two distinct molecular mechanisms in sorghum buds: one induces dormancy by reducing CK and sugars, whereas the other inhibits flowering by activating SbCN2. Given the agricultural significance of TFL1‐like genes, the rapid regulation of SbCN2 by light signals in axillary buds revealed in this study warrants further investigation to explore its potential in crop improvement strategies. [ABSTRACT FROM AUTHOR]

Fruit skin color and physical quality are important for customer acceptability and market value. Therefore, this study aimed to evaluate the effect of pneumatic defoliation on the fruit quality, coloration, and anthocyanin content of 'Fuji' apples. Apple trees were subjected to no defoliation (control) and defoliation at low (0.6 bar) and high (0.9 bar) air pressure 20 days before harvest at 1 km/h of tractor speed. High-defoliation treatment increased the leaf damage rate but did not significantly affect the defoliation rate compared to low-defoliation treatment. Additionally, photosynthetically active radiation and solar irradiance inside the tree canopies were highest in the high-defoliation group, followed by the low-defoliation and control groups. With the exception of higher firmness in the high-defoliation treatment, pneumatic defoliation treatments had little effect on fruit size and weight, titratable acidity, soluble solids content, the starch pattern index, and the sunburn incidence of fruit. Compared with that of the control group, both defoliation treatments significantly increased the a* and C values and decreased the ho values of the fruit color. Moreover, both defoliation treatments significantly increased anthocyanin content and upregulated the anthocyanin biosynthesis genes (MdPAL, MdCHS, MdCHI, MdF3H, MdANS, MdANS, MdUFGT) and the transcription factor (MdMYB10). A Pearson′s correlation analysis also showed that anthocyanin production was strongly correlated with each of the anthocyanin biosynthesis genes, especially in the pneumatic defoliation treatments. Conclusively, the results show that pneumatic defoliation at low pressure bars could be an effective strategy for improving the red coloration of 'Fuji' apples. [ABSTRACT FROM AUTHOR]