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Over-dose pesticide application disrupts plant physiological processes and soil biological functions; however, the toxicity mechanisms of pesticides and the effectiveness of mitigation measures are still unclear. Our review shows that over-dose of pesticide can cause plant phytotoxicity by enhancing reactive oxygen species and cellular membrane electrolyte leakage, which subsequently decrease chlorophyll biosynthesis, vegetative growth and yield. However, the optimum use of pesticides (insecticides at 0.21 kg a.i. ha-1; herbicides at 1.44 kg a.i. ha-1 and fungicides at =0.4 kg a.i. ha-1) may not interfere with plant physiological functions, while indirectly improving plant nutrients absorption, translocation and yield. In the soil system, pesticide application decreases microbial population by disrupting the microbial metabolism and cellular protein denaturation. Moreover, pesticide application can restrict (by adsorption, etc.) glucose release from organic matter by decreasing the hydrolysis of extracellular enzymes, thereby reducing the labile C source for microbes and resulting in lower soil organic carbon cycling. The pesticide residue can decrease biological nitrogen fixation and nitrogen mineralization by decreasing diazotrophs and saprophytic bacterial population due to cellular hyperkinesis and misfunctions, respectively. Organo-phosphate pesticides can induce oxidative stress to microbes which can affect phosphorus (P) mineralization, but may also enhance P-solubilizing bacterial activities and P availability. The use of biosurfactants, exogenously induced microbes, and soil amendments (e.g., biochar) can effectively remediate pesticide toxicity through solubilization, microbial catabolism and sorption of pesticides by 70%, 78% and 69%, respectively. However, field application of biosurfactants and optimization of biochar characteristics remain challenging for effective pesticide sorption and remediation. [ABSTRACT FROM AUTHOR]

SUMMARY: Food security is threatened by climate change, with heat and drought being the main stresses affecting crop physiology and ecosystem services, such as plant–pollinator interactions. We hypothesize that tracking and ranking pollinators' preferences for flowers under environmental pressure could be used as a marker of plant quality for agricultural breeding to increase crop stress tolerance. Despite increasing relevance of flowers as the most stress sensitive organs, phenotyping platforms aim at identifying traits of resilience by assessing the plant physiological status through remote sensing‐assisted vegetative indexes, but find strong bottlenecks in quantifying flower traits and in accurate genotype‐to‐phenotype prediction. However, as the transport of photoassimilates from leaves (sources) to flowers (sinks) is reduced in low‐resilient plants, flowers are better indicators than leaves of plant well‐being. Indeed, the chemical composition and amount of pollen and nectar that flowers produce, which ultimately serve as food resources for pollinators, change in response to environmental cues. Therefore, pollinators' preferences could be used as a measure of functional source‐to‐sink relationships for breeding decisions. To achieve this challenging goal, we propose to develop a pollinator‐assisted phenotyping and selection platform for automated quantification of Genotype × Environment × Pollinator interactions through an insect geo‐positioning system. Pollinator‐assisted selection can be validated by metabolic, transcriptomic, and ionomic traits, and mapping of candidate genes, linking floral and leaf traits, pollinator preferences, plant resilience, and crop productivity. This radical new approach can change the current paradigm of plant phenotyping and find new paths for crop redomestication and breeding assisted by ecological decisions. Significance Statement: While climate change threatens food production through affecting plant physiology and pollinating ecosystem services, plant phenotyping platforms aim at identifying traits of resilience mostly based on vegetative indexes. However, since flowers are better indicators of the plant well‐being and provide food for pollinators, we propose to use the senses of animal pollinators and their preferences to assist in the identification of flower traits of resilience to abiotic stresses for plant breeding based on ecological decisions. [ABSTRACT FROM AUTHOR]

Recent studies have highlighted several advantages in using well-formulated blends of plant growth-promoting rhizobacteria (PGPR) that promote synergistic interactions over single PGPR strains. However, developing PGPR consortia (i.e., blends) that are effective in multiple crop cultivars is challenging. Five PGPR blends were evaluated for broad-spectrum growth promotion efficacy. Rhizosphere bacteria were isolated from crops grown in Texas to identify indigenous PGPR strains, and those with biological activity against fungal pathogens were used to formulate three PGPR blends, hereafter called TX1, TX2 and TX3. Using two corn and two cotton cultivars of contrasting resistance levels to fungal pathogens, the efficacy of these three PGPR blends was compared to two previously reported blends (AU9 and AU8). In addition, effects of the PGPR blends on the crops' transpiration rate and stomatal conductance were evaluated. The newly identified PGPR strains belong to five bacterial taxonomic groups: Bacillus, Paenibacillus, Pantoea, Peribacillus and Priestia. All PGPR blends increased the length and weight of root and shoot of the susceptible cultivars. For the resistant cultivars, blends AU8, TX1, TX2 and TX3 enhanced at least one of the corn growth parameters, while only TX2 and TX3 increased growth of the cotton plants. Resistant corn plants treated with AU8, TX1, TX2 or TX3 blend, and resistant cotton plants treated with AU8 or TX3 blend showed increased transpiration rate and stomatal conductance compared with untreated plants, but no significant differences were observed for the susceptible cultivars. The findings indicate that the PGPR blends showed better growth promotion efficacy in susceptible cultivars than in resistant cultivars. Only blends TX2 and TX3 made of PGPR strains from across four and three bacterial taxonomic groups, respectively, significantly increased growth of all four cultivars, regardless of resistance levels, suggesting that these blends have a great potential to enhance growth of a broad range of corn and cotton cultivars. [ABSTRACT FROM AUTHOR]

Summary Drought stress substantially impacts crop physiology resulting in alteration of growth and productivity. Understanding the genetic and molecular crosstalk between stress responses and agronomically important traits such as fibre yield is particularly complicated in the allopolyploid species, upland cotton (Gossypium hirsutum), due to reduced sequence variability between A and D subgenomes. To better understand how drought stress impacts yield, the transcriptomes of 22 genetically and phenotypically diverse upland cotton accessions grown under well‐watered and water‐limited conditions in the Arizona low desert were sequenced. Gene co‐expression analyses were performed, uncovering a group of stress response genes, in particular transcription factors GhDREB2A‐A and GhHSFA6B‐D, associated with improved yield under water‐limited conditions in an ABA‐independent manner. DNA affinity purification sequencing (DAP‐seq), as well as public cistrome data from Arabidopsis, were used to identify targets of these two TFs. Among these targets were two lint yield‐associated genes previously identified through genome‐wide association studies (GWAS)‐based approaches, GhABP‐D and GhIPS1‐A. Biochemical and phylogenetic approaches were used to determine that GhIPS1‐A is positively regulated by GhHSFA6B‐D, and that this regulatory mechanism is specific to Gossypium spp. containing the A (old world) genome. Finally, an SNP was identified within the GhHSFA6B‐D binding site in GhIPS1‐A that is positively associated with yield under water‐limiting conditions. These data lay out a regulatory connection between abiotic stress and fibre yield in cotton that appears conserved in other systems such as Arabidopsis. [ABSTRACT FROM AUTHOR]

Climate change scenarios and water restrictions are key challenges for Mediterranean citriculture, requiring sustainable deficit irrigation (DI) strategies to ensure sustainable yields. Further research on the physiological pathways that regulate crop responses to water stress is necessary. This work describes the physiological limitations induced under drought conditions in young Navelina orange trees, including the crop's capability to recuperate its physiological status upon rewatering and after water withholding. A trial was conducted in two-year-old trees subjected to three irrigation treatments: a full irrigation treatment (FI) and two different DI strategies. The results show significant decreases in gas exchange rates for stem water potential (ΨStem) values below −1.5 MPa, evidencing diffusive limitations from drought stress. Additionally, there was evidence of increased osmolyte synthesis, a preventative response to oxidative damage. Significantly increased levels of proline (Pro) and malondialdehyde (MDA) were observed with higher levels of water stress (ΨStem < −1.8 MPa), which leads us to assume that this threshold signals the presence of oxidative damage with no capacity for subsequent recovery, probably affecting the final yield. [ABSTRACT FROM AUTHOR]

A positive relationship between protein concentration and yield has been documented in different combinations of genotype and environment, often under potential conditions. However, the ecophysiological bases underlying this positive relationship under heat stress (HS) and drought stress (DS) during seed filling are still lacking. Our objective was to evaluate the relationship between seed protein content and concentration with yield in field experiments exposed to HS, DS and HS × DS interaction during the seed filling. Two field experiments were conducted and assimilates accumulation, remobilization and redistribution patterns were analysed in high and low seed protein soybean genotypes. The crop was exposed to four treatments: control (ambient temperature and soil water content near field capacity), HS (episodes above 32°C, 6 h d−1) during 15 days, DS (soil water content ≤25% of field capacity) during the whole seed filling and HS × DS. Significant and positive relationships between seed protein content and concentration with yield were observed across treatments and genotypes. Under DS and HS × DS, assimilates available during the seed filling decreased, and assimilates remobilization and partition to seeds were limited, responses significantly associated with seed protein content and concentration, and yield reductions. Furthermore, we demonstrated here that the high leaf N content at the beginning of seed filling, the short early reproductive phase duration, the high source to sink ratio and the high dry matter stem remobilization capacity, as well as the low seed number and high seed weight are intrinsic characteristics of the high protein genotype that could be associated with its high seed protein content and concentration and yield under stressful conditions. This knowledge is key to develop soybean management strategies to improve seed protein level and yield under contrasting productive scenarios. [ABSTRACT FROM AUTHOR]

An experimental study was conducted to assess the detrimental effect of ground-level ozone (O3) on garlic physiology and to find out appropriate control measures against ground-level O3, at TNAU-Horticultural Research farm, Udhagamandalam. Elevated ground ozone levels significantly decreased garlic leaf chlorophyll, photosynthetic rate, stomatal conductance, total soluble solids and pungency. The garlic chlorophyll content was highest in ambient ozone level and lowest in elevated ozone@200 ppb, highest stomatal conductance was recorded in ambient ozone with foliar spray of 3%Panchagavya, and the lowest was observed in elevated ozone@200 ppb. Since the elevated O3 had reduced in garlic photosynthetic rate significantly the lowest was observed in elevated O3@200 ppb and the highest photosynthetic rate was observed in ambient Ozone with foliar spray 3% of panchagavya after a week. The antioxidant enzymes of garlic were increased with increased concentration of tropospheric ozone. The highest catalase (60.97 µg of H2O2/g of leaf) and peroxidase (9.13 ΔA/min/g of leaf) concentration was observed at 200 ppb elevated ozone level. Garlic pungency content was highest in ambient ozone with foliar spray of 0.1% ascorbic acid and the lowest was observed under elevated O3@200 ppb. Highest total soluble solids were observed in ambient ozone with foliar spray of 3%Panchagavya and the lowest observed in elevated ozone@200 ppb. Thus, tropospheric ozone has a detrimental impact on the physiology of crops, which reduced crop growth and yield. Under elevated O3 levels, ascorbic acid performed well followed by panchagavya and neem oil. The antioxidant such as catalase and peroxidase had positive correlation among themselves and had negative correlation with chlorophyll content, stomatal conductance, photosynthetic rate, pungency and TSS. The photosynthetic rate has high positive correlation with chlorophyll content, pungency and TSS. Correlation analysis confirmed the negative effects of tropospheric ozone and garlic gas exchange parameters and clove quality. The ozone protectants will reduce stomatal opening by which the entry of O3 in to the cell will be restricted and other hand they also will alleviate ROS and allied stresses. [ABSTRACT FROM AUTHOR]

Background: Anaerobic conditions in waterlogged soil affect germination rate significantly reducing rice yields. Under wet direct seeded condition, only limited availability of rice genotypes are suitable for anaerobic germination. So, there is an urgent need to identify rice genotypes for enhanced germination even under anoxic stress. Methods: Experiment was conducted in glass house, Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore. In this study, 22 rice germplams with three replications were evaluated for seed and seedling traits underlying anaerobic germination tolerance. Main aim of this study is to explore the starch and sugar relation under anoxic stress and identifying tolerant genotypes for direct seeded rice cultivation. Result: Tolerant genotypes had early emergences, higher shoot and root length along with higher starch degradation and sugar accumulation under waterlogged condition. Cluster analysis revealed that Karuppukavuni, Kalanamak, CBMAS 14065 and Kodavilayan were identified as tolerant genotypes and suitable for wet direct seeded rice cultivation. Finally higher starch degradation coupled with higher accumulation of glucose and fructose were the key traits underlying anaerobic germination tolerance in tolerant genoytpes. Shoot length, root length and sucrose contents had higher genotypic coefficient of variance, phenotypic coefficient of variance coupled with high heritability indicating scope for enhancing anaerobic germination tolerance. [ABSTRACT FROM AUTHOR]

Reproductive development of fruiting trees, including mango (Mangifera indica L.), is limited by nonstructural carbohydrates. Competition for sugars increases with cropping, and consequently, vegetative growth and replenishment of starch reserves may reduce with high yields, resulting in interannual production variability. While the effect of crop load on photosynthesis and the distribution of starch within the mango tree has been studied, the contribution of starch and sugars to different phases of reproductive development requires attention. This review focuses on mango and examines the roles of non-structural carbohydrates in fruiting trees to clarify the repercussions of crop load on reproductive development. Starch buffers the plant’s carbon availability to regulate supply with demand, while sugars provide a direct resource for carbon translocation. Sugar signalling and interactions with phytohormones play a crucial role in flowering, fruit set, growth, ripening and retention, as well as regulating starch, sugar and secondary metabolites in fruit. The balance between the leaf and fruit biomass affects the availability and contributions of starch and sugars to fruiting. Crop load impacts photosynthesis and interactions between sources and sinks. As a result, the onset and rate of reproductive processes are affected, with repercussions for fruit size, composition, and the inter-annual bearing pattern. [ABSTRACT FROM AUTHOR]

This document discusses the importance of understanding the nutrition and physiology of fruit crops. Fruit crops require significant inputs of pesticides and fertilizers, but they have lower rates of energy use, soil erosion, and nitrogen loss compared to annual crops. Fruits are a major source of nutrients and bioactive compounds. The document also highlights the need for continuous research and scientific advances to prevent and treat nutrition problems in fruit trees. The document includes five research papers that investigate various aspects of fruit physiology and nutrition, such as the effects of cultivation practices on fruit quality, alternative nutrient sources for potted olives, the impacts of salinity stress on pomegranate and strawberry, and ways to alleviate cracking in figs at harvest. [Extracted from the article]

Climate change caused by global warming involves crucial plant growth factors such as atmospheric CO2 concentration, ambient temperature or water availability. These stressors usually co-occur, causing intricate alterations in plant physiology and development. This work focuses on how elevated atmospheric CO2 levels, together with the concomitant high temperature, would affect the physiology of a relevant crop, such as broccoli. Particular attention has been paid to those defence mechanisms that contribute to plant fitness under abiotic stress. Results show that both photosynthesis and leaf transpiration were reduced in plants grown under climate change environments compared to those grown under current climate conditions. Furthermore, an induction of carbohydrate catabolism pointed to a redistribution from primary to secondary metabolism. This result could be related to a reinforcement of cell walls, as well as to an increase in the pool of antioxidants in the leaves. Broccoli plants, a C3 crop, grown under an intermediate condition showed activation of those adaptive mechanisms, which would contribute to coping with abiotic stress, as confirmed by reduced levels of lipid peroxidation relative to current climate conditions. On the contrary, the most severe climate change scenario exceeded the adaptive capacity of broccoli plants, as shown by the inhibition of growth and reduced vigour of plants. In conclusion, only a moderate increase in atmospheric CO2 concentration and temperature would not have a negative impact on broccoli crop yields. [ABSTRACT FROM AUTHOR]

French marigold (Tagetes patula L.) is an aromatic plant known for its repellent effects on pests. It is traditionally grown in fields near many vegetable crops, including potato (Solanum tuberosum L.). However, the effects of marigold essential oil (EO) on the physiology of neighboring crops have been neglected in research. The aim of this study was to establish, for the first time, a comprehensive phytohormone profile of potato plants exposed to French marigold EO for different time periods (4, 8 and 12 h). Endogenous levels of all major phytohormone groups, determined by HPLC–MS analysis, showed altered phytohormone responses of EO-exposed potato plants. The most affected were stress-related phytohormones: abscisic acid–glucose ester, 1-aminocyclopropane-1-carboxylic acid, and jasmonic acid. Increased levels of jasmonic acid, cytokinins, storage form of abscisic acid together with decreased levels of indole-3-acetic acid and ethylene precursor were observed. In most of the analyzed phytohormone groups similar response pattern was observed—an increase in levels after short time exposure (4 h), followed by a decrease to control values after prolonged exposure (8 h and 12 h). Expression levels of genes involved in biosynthesis and catabolism of stress-related phytohormones, obtained by de novo bioinformatic processing of data from cDNA microarray analysis, revealed that jasmonic acid biosynthetic pathway was the most affected, with the highest number of altered transcripts and with one of the genes from this pathway (12-oxophytodienoate reductase 1-like) exhibiting the highest expression rate. [ABSTRACT FROM AUTHOR]

This document is an editorial published in the journal Frontiers in Plant Science. It discusses the importance of using plant architectural models to understand plant growth and its interactions with the environment. The editorial highlights the different types of models that can be used, ranging from statistical models to mechanistic models. It also provides examples of research topics covered in the journal, including the analysis of plant morphology and structure, physiological mechanisms underlying plant productivity, and the interactions between genetic traits and management practices. The editorial emphasizes the need for further work in integrating different models and developing universal simulators for plant breeding and crop optimization. [Extracted from the article]

Rice is one of the major food crops, particularly in Asia. However, it is vulnerable to high temperature and has high yield fluctuations. Monitoring crop growth and physiological responses to high temperatures can help us better understand the agricultural impacts of global warming. The aim of this study is to monitor growth, development, and physiological responses to high temperature conditions on paddy rice and to assess their combined effects on yield. In this study, changes to growth, maturity, and senescence in paddy rice throughout the growing season were identified under elevated air temperature conditions created by a temperature gradient field chamber (TGFC). That facility provides a gradient from the ambient air temperature (AT) to 3 °C above AT (AT + 3 °C). To represent crop physiology and productivity, we measured the plant height, chlorophyll, normalized difference vegetation index (NDVI), and maximum photosynthetic rate (Amax) to assess growth and physiological processes, and heat stress effects on four yield measurements were assessed using the heating degree day index. Rice height increased more rapidly in the AT + 3 °C treatment from the early growth stage to heading, while SPAD and NDVI decreased more rapidly at AT after heading. The Amax of AT and AT + 3 °C was not significantly different in the tillering stage. However, it was higher at AT in the booting stage but higher at AT + 3 °C in the grain filling stage. These results indicate that paddy rice was not affected by heat stress at the tillering stage, but a cumulative effect emerged by the booting stage. Further, photosynthetic capacity was maintained much later into the grain filling stage at AT + 3 °C. These results will be useful for understanding the growth and physiological responses of paddy rice to global warming. [ABSTRACT FROM AUTHOR]

Zinc-oxide nanoparticles (ZnO-NP) effect on crop physiology and zinc recovery remains poorly studied for acidic-sandy soils. To address this, greenhouse pot (plastic-pots, 6 kg soil, maize) experiments with ZnO-NP (50, 100, 150, 200 mg kg−1) applied via different methods (soil-drench, seed-coating and foliar-spray) was conducted in a 60 days study. Results revealed that ZnO-NP via seed-coating (100 mg kg−1) and soil-drench (150 mg kg−1) enhanced shoot and total P uptake, while ZnO-NPs (foliar) (50 mg kg−1) enhanced maize growth (6–11%), with agronomic and physiological improvements ultimately resulted in greater biomass (16–20%), Zn agronomic efficiency and uptake. Compared to ZnSO4 treatment and the control, seed-coating with 100 mg kg−1 ZnO-NP increased leaf chlorophyll and pigment content by 12–127%. Principal component analysis revealed a close association among growth traits, plant pigments, fluorescence parameters, total Zn and P concentration, and uptake with total biomass as influenced by ZnO-NPs. Thus, compared to conventional ZnSO4 and higher dosages of ZnO-NPs, foliar-spray of ZnO-NP at 50 mg kg−1, seed-coating at 100 mg kg−1, or soil-drench at 150 mg kg−1 increased maize biochemical characteristics, growth, biomass, and Zn agronomic efficiency. These elucidate important implications of ZnO-NP application for increasing plant development and Zn biofortification in acidic-sandy soils. [ABSTRACT FROM AUTHOR]

Proline is an integral osmoprotectant produced in plants under stressed conditions to reduce the adverse effects of any abiotic stress. For the induction of drought stress tolerance exogenously applied proline could be an effective strategy. To evaluate this, a pot experiment was designed to mitigate drought stress on wheat through exogenous application of proline. Two water stress levels i.e., 70% and 30% (applied after 4 weeks) and 30mM proline was either applied in soil (after one week of water stress) or as foliar application (after 1 and 2 week of drought stress. In, another treatment double spray of proline was applied after 1 and 2 weeks of drought stress. When compared with control the proline application has a considerable share in improving plant growth attributes under drought stress. Maximum improvement in plant height (53.99 cm), count of tillers plant-1 (3.33), root fresh weight (7.15 g), root dry weight (1.28 g), shoot fresh weight (32.75 g), shoot dry weight (3.03 g), chlorophyll contents (37.13 mg kg-1), N (31%) and P concentration (0.23%) in plants was observed when proline was applied at 1st week and repeated after 2nd week of drought stress. In addition, 46% reduction in Na+\K+ ratio (0.28) in plant leaves was also observed in proline foliar application. The foliar application of proline showed better response than that of soil application. Proline application as foliar spray in two splits during drought stress sounds stronger effects to improve growth and physiology of wheat crop. [ABSTRACT FROM AUTHOR]

Background: The cotton growing farmers in India are facing major problem at the time of harvest due to labor shortages, asynchronized boll opening, leaf trash in the cotton, which is reducing the boll picking efficiency and fiber quality. Presently, the Indian cotton industry is moving towards mechanical harvesting by cotton harvester. Defoliation or leaf abscission is induced in cotton as a natural physiological process which usually is inadequate for a complete mechanical harvest of cotton. Defoliation before harvest is often induced by managing the plants so that senescence, abscission (separation) layer development and leaf drop are encouraged. Chemical defoliants induce leaf abscission, hasten mature boll dehiscence and inhibit regrowth. Selection of appropriate defoliants is one of the critical decisions in cotton production. Their use can result in increased manual as well as machine harvest efficiency, reducing boll rot and the trash in seed cotton. The physiological basis of defoliation in cotton is essential to understand the role of appropriate defoliant with time of application. Hence, the objective of the study was to evaluate the defoliation efficiency, boll opening percentage and to know the physiological basis of defoliation in response to different defoliants and time of application in high density Cotton cultivation which eases the mechanical harvesting. Methods: In this field investigation during 2018 - 2019 at Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore was carried with seven different defoliants and three different time of defoliants application were fixed based on crop maturity and duration of the crop. In this study, high density cotton variety CO 17 was used as experimental material. A series of lab and field analysis were determined on defoliation process, physiological attributes, boll opening percentage and seed yield and quality. The collected data were subjected to statistical analysis. Result: Our investigation exploring the effect of different defoliants on physiological, biochemical, yield and quality parameters of high density Cotton. Among the different defoliants and time of applications, two defoliants and two times of applications works better in terms of better defoliation, boll opening rate, physiology, yield and quality. The physiological and biochemical effects of defoliants on defoliation process were discussed. The present work will be useful for mechanized picking with these effective defoliants without loss of yield and quality loss in cotton. [ABSTRACT FROM AUTHOR]

The deleterious effects of ozone (O3) pollution on crop physiology, yield, and productivity are widely acknowledged. It has also been assumed that C4 crops with a carbon concentrating mechanism and greater water use efficiency are less sensitive to O3 pollution than C3 crops. This assumption has not been widely tested. Therefore, we compiled 46 journal articles and unpublished datasets that reported leaf photosynthetic and biochemical traits, plant biomass, and yield in five C3 crops (chickpea, rice, snap bean, soybean, and wheat) and four C4 crops (sorghum, maize, Miscanthus × giganteus, and switchgrass) grown under ambient and elevated O3 concentration ([O3]) in the field at free-air O3 concentration enrichment (O3-FACE) facilities over the past 20 y. When normalized by O3 exposure, C3 and C4 crops showed a similar response of leaf photosynthesis, but the reduction in chlorophyll content, fluorescence, and yield was greater in C3 crops compared with C4 crops. Additionally, inbred and hybrid lines of rice and maize showed different sensitivities to O3 exposure. This study quantitatively demonstrates that C4 crops respond less to elevated [O3] than C3 crops. This understanding could help maintain cropland productivity in an increasingly polluted atmosphere. [ABSTRACT FROM AUTHOR]

Smoke is one of the fire-related cues that can alter vegetation communities' compositions, by promoting or excluding different plant species. For over 30 years, smoke-derived compounds have been a hot topic in plant and crop physiology. Research in this field was initiated in fire-prone areas in Australia, South Africa and some countries of both Americas, mostly with Mediterranean-type climates. Then, research extended to regions with moderate climates, like Central European countries; this was sometimes determined by the fact that in those regions, extensive prescribed or illegal burning (swailing) occurs. Hence, this review updates information about the effects of smoke compounds on plant kingdoms in different regions. It also focuses on research advances in the field of the physiological effects of smoke chemicals, mostly karrikins, and attempts to gather and summarize the current state of research and opinions on the roles of such compounds in plants' lives. We finish our review by discussing major research gaps, which include issues such as why plants that occur in non-fire-prone areas respond to smoke chemicals. Have recent climate change and human activities increased the risk of wildfires, and how may these affect local plant communities through physiologically active smoke compounds? Is the response of seeds to smoke and smoke compounds an evolutionarily driven trait that allows plants to adapt to the environment? What can we learn by examining post-fire smoke on a large scale? [ABSTRACT FROM AUTHOR]

The deleterious effects of ozone (O3) pollution on crop physiology, yield, and productivity are widely acknowledged. It has also been assumed that C4 crops with a carbon concentrating mechanism and greater water use efficiency are less sensitive to O3 pollution than C3 crops. This assumption has not been widely tested. Therefore, we compiled 46 journal articles and unpublished datasets that reported leaf photosynthetic and biochemical traits, plant biomass, and yield in five C3 crops (chickpea, rice, snap bean, soybean, and wheat) and four C4 crops (sorghum, maize, Miscanthus × giganteus, and switchgrass) grown under ambient and elevated O3 concentration ([O3]) in the field at free-air O3 concentration enrichment (O3-FACE) facilities over the past 20 y. When normalized by O3 exposure, C3 and C4 crops showed a similar response of leaf photosynthesis, but the reduction in chlorophyll content, fluorescence, and yield was greater in C3 crops compared with C4 crops. Additionally, inbred and hybrid lines of rice and maize showed different sensitivities to O3 exposure. This study quantitatively demonstrates that C4 crops respond less to elevated [O3] than C3 crops. This understanding could help maintain cropland productivity in an increasingly polluted atmosphere. [ABSTRACT FROM AUTHOR]

Waterlogging constrains crop yields in many regions around the world. Despite this, key drivers of crop sensitivity to waterlogging have received little attention. Here, we compare the ability of the SWAGMAN Destiny and CERES models in simulating soil aeration index, a variable contemporaneously used to compute three distinct waterlogging indices, denoted hereafter as WIDestiny, WIASD1, and WIASD2. We then account for effects of crop growth stage and soil temperature on waterlogging impact by introducing waterlogging severity indices, WIGrowth, which accommodates growth stage tolerance, and WI Plus, which accounts for both soil temperature and growth stage. We evaluate these indices using data collected in pot experiments with genotypes "Yang mai 11" and "Zheng mai 7698" that were exposed to both single and double waterlogging events. We found that WIPlus exhibited the highest correlation with yield (-0.82 to -0.86) suggesting that waterlogging indices which integrate effects of temperature and growth stage may improve projections of yield penalty elicited by waterlogging. Importantly, WIPlus not only allows insight into physiological determinants, but also lends itself to remote computation through satellite imagery. As such, this index holds promise in scalable monitoring and forecasting of crop waterlogging. [ABSTRACT FROM AUTHOR]

• Severe drought negatively impacts crop physiology leading to a decline in crop yields • There is limited knowledge regarding the acclimation of lablab to water deficit. • Ten lablab bean seedlings were investigated for response to water stress. • Photosystem II quantum yield increased in severe water stress, indicating improved photosynthetic efficiency • Water stress significantly reduced shoot and root length of lablab seedlings. • Increased activity of ascorbate peroxidase led to increased production of reactive oxygen species. Drought is a major crop productivity-limiting factor, which adversely affects growth and yield worldwide. Lablab (Lablab pupureus [L.] Sweet), is better adapted to withstand drought stress, however, characterization of lablab in Kenya has not been undertaken and there is limited knowledge on plant response to drought stress. Ten lablab genotypes were evaluated under greenhouse to determine the morpho-physiological and biochemical response at the seedling stage. The study revealed significant differential responses among lablab genotypes to water stress. The interaction between the water stress and the genotypes significantly affected the evaluated traits. Genotypes D1 and D6 showed significantly increased and superior morphological adaptation, respectively, indicating enhanced adaptation for tolerance to water stress. Significant variations of ascorbate peroxidase, guaiacol peroxidase and catalase activities were detected during the experimental period. The plants exhibited varying non-enzymatic antioxidants and osmolytes with an increase in proline, total phenol and water-soluble carbohydrates and a decline in free amino acids and water-soluble proteins under severe water stress. Genotype D10 recorded high antioxidant enzymatic activity and water-soluble carbohydrates, whereas D1 accumulated more proline and proteins, indicating better adaptation in scavenging reactive oxygen species to prevent membrane damage. The higher photosynthetic efficiency of seedlings of genotype D1 and superior morphological adaptation of D6 indicated better agronomic adaptation to severe water stress and could be utilized in plant breeding programmes for tolerance to drought. [ABSTRACT FROM AUTHOR]

Foliar application of Atonik (sodium nitrophenolate) at crop critical growth stages is expected to improve crop physiology, morphology, and productivity. The present field study was conducted at the University of Agriculture, Faisalabad in autumn season of 2018 and 2019. Water deficit conditions were imposed by skip irrigation method. Plants were treated with foliar application of Atonik 10 (mg L−1) to evaluate the physiological, morphological, yield, and yield causative attributes of maize grown under deficit irrigation treatments. Randomized complete block design (RCBD) with split plots arrangement was used to layout the experiment having three replications. It was revealed that application of Atonik improved the crop's physiological attributes: relative leaf water contents (RLWC by 10%), chlorophyll contents (14%), and carotenoids content (15%) under water deficit conditions. Similarly, Atonik application augmented the leaf length at maturity, the number of green leaves at harvesting, and the number of grains row−1 of maize by 7%, 20% and 12%, respectively. Moreover, the application of Atonik amended the 100-grains weight, grain yield, and biological yield by 8%, 9% and 20%, respectively. In crux, application of Atonik is an excellent strategy to alleviate the detrimental influence of water deficit on physiological, morphological, and yield causative attributes of maize. [ABSTRACT FROM AUTHOR]

Flowering dogwoods (Cornus florida L.) are drought-sensitive ornamental trees. Two trials (in 2021 and 2022) were conducted to evaluate the physiological changes induced as a result of drought conditions. In an outdoor setting, trees were organized in a randomized complete block design. Three different irrigation treatments were applied at 125%, 25%, and 10% (control, moderate, and severe drought, respectively) of their daily water usage (evapotranspiration). The two physiological parameters normalized difference vegetation index (NDVI) and leaf moisture potential were collected every week for 1 month. Plant growth data (height and width) were collected at the beginning and the end of the study. Normalized difference vegetation index data collected with a handheld NDVI meter and a Sentera NDVI sensor mounted on an unmanned aerial vehicle (UAV) were correlated for ground truthing. In 2021, control plants had a greater plant width increase and shoot biomass, whereas no significant differences in growth were observed among the treatments in 2022. In both trials, the NDVI was the greatest for control plants compared with the other treatments on days 7, 14, 21, and 27. In both studies, no differences were observed for leaf moisture potential on day 7, but was greatest for controls on days 14, 21, and 27. The correlation between the handheld NDVI and the UAV NDVI was found to be strong and positive, ranging from 0.84 to 0.93 (trial 1: P ≤ 0.0001, P ≤ 0.0001, P = 0.0002, and P ≤ 0.0001; trial 2: P = 0.0002, P ≤ 0.0001, P ≤ 0.0001, and P ≤ 0.0001 for weeks 1–4, respectively). This information will be applicable to understanding the physiology of the crop and the inclusion of emerging technology in crop production and monitoring.

Climate change scenarios and water restrictions are key challenges for Mediterranean citriculture, requiring sustainable deficit irrigation (DI) strategies to ensure sustainable yields. Further research on the physiological pathways that regulate crop responses to water stress is necessary. This work describes the physiological limitations induced under drought conditions in young Navelina orange trees, including the crop’s capability to recuperate its physiological status upon rewatering and after water withholding. A trial was conducted in two-year-old trees subjected to three irrigation treatments: a full irrigation treatment (FI) and two different DI strategies. The results show significant decreases in gas exchange rates for stem water potential (ΨStem) values below −1.5 MPa, evidencing diffusive limitations from drought stress. Additionally, there was evidence of increased osmolyte synthesis, a preventative response to oxidative damage. Significantly increased levels of proline (Pro) and malondialdehyde (MDA) were observed with higher levels of water stress (ΨStem < −1.8 MPa), which leads us to assume that this threshold signals the presence of oxidative damage with no capacity for subsequent recovery, probably affecting the final yield.

Flowering dogwoods (Cornus florida L.) are drought-sensitive ornamental trees. Two trials (in 2021 and 2022) were conducted to evaluate the physiological changes induced as a result of drought conditions. In an outdoor setting, trees were organized in a randomized complete block design. Three different irrigation treatments were applied at 125%, 25%, and 10% (control, moderate, and severe drought, respectively) of their daily water usage (evapotranspiration). The two physiological parameters normalized difference vegetation index (NDVI) and leaf moisture potential were collected every week for 1 month. Plant growth data (height and width) were collected at the beginning and the end of the study. Normalized difference vegetation index data collected with a handheld NDVI meter and a Sentera NDVI sensor mounted on an unmanned aerial vehicle (UAV) were correlated for ground truthing. In 2021, control plants had a greater plant width increase and shoot biomass, whereas no significant differences in growth were observed among the treatments in 2022. In both trials, the NDVI was the greatest for control plants compared with the other treatments on days 7, 14, 21, and 27. In both studies, no differences were observed for leaf moisture potential on day 7, but was greatest for controls on days 14, 21, and 27. The correlation between the handheld NDVI and the UAV NDVI was found to be strong and positive, ranging from 0.84 to 0.93 (trial 1: P ≤ 0.0001, P ≤ 0.0001, P = 0.0002, and P ≤ 0.0001; trial 2: P = 0.0002, P ≤ 0.0001, P ≤ 0.0001, and P ≤ 0.0001 for weeks 1-4, respectively). This information will be applicable to understanding the physiology of the crop and the inclusion of emerging technology in crop production and monitoring. [ABSTRACT FROM AUTHOR]

Little is known about the photosynthetic physiology of guar (Cyamopsis tetragonoloba L. Taub), a legume crop, including how photosynthetic parameters intrinsically vary among germplasm and their recovery from water stress. To address this, two greenhouse studies were conducted: Study-1 to compare photosynthetic light response (AN–I) curves and related parameters in three contrasting guar genotypes under optimal and post-water deficit conditions; and Study-2 to quantify photosynthetic parameters in 44 guar genotypes and explore inter-relationships with plant growth parameters. In Study-1, the mean net photosynthetic rate (AN) statistically peaked with 1500 μmol (photons) m −2 s −1, though the maximum AN [33.29 μmol (CO2) m−2 s−1] was modeled to occur with 1950 μmol (photons) m −2 s −1. The light compensation point (Icomp), dark respiration rate (RD), and maximum quantum yield (Ф(I0)) were modeled to be 49.9 μmol (photons) m−2 s−1, 2.62 μmol (CO2) m−2 s−1, and 0.0526 μmol (CO2) μmol−1 (photons), respectively. Photosynthesis in guar was resilient to water stress. Despite reductions in growth, specific leaf area (SLA), and other growth parameters, persistently drought-stressed guar plants, on average, exhibited rapid and full recovery of photosynthetic functions when watered. Genotypes differed in their capacity to recover to some degree. In Study-2, AN differed only between two of the 44 genotypes tested, corresponding to the minimum and maximum AN values. There were no relationships between AN and most plant growth parameters. This finding suggested there is low potential to use point measurements of AN as a selection parameter for increased guar productivity. [ABSTRACT FROM AUTHOR]

Nanotechnology is rapidly emerging and innovative interdisciplinary field of science. The application of nanomaterials in agricultural biotechnology has been exponentially increased over the years that could be attributed to their uniqueness, versatility, and flexibility. The overuse of nanomaterials makes it crucial to determine their fate and distribution in the in vitro (in cell and tissue cultures) and in vivo (in living species) biological environments by investigating the nano-biointerface. The literature states that the beneficial effects of nanoparticles come along with their adverse effects, subsequently leading to an array of short-term and long-term toxicities. It has been evident that the interplay of nanoparticles with abiotic and biotic communities produces several eco-toxicological effects, and the physiology and biochemistry of crops are greatly influenced by the metabolic alterations taking place at cellular, sub-cellular, and molecular levels. Numerous risk factors affect nanoparticle's accumulation, translocation, and associated cytogenotoxicity. This review article summarizes the contributing factors, possible mechanisms, and risk assessment of hazardous effects of various types of nanoparticles to plant health. The methods for evaluating the plant nanotoxicity parameters have been elaborated. Conclusively, few recommendations are put forward for designing safer, high-quality nanomaterials to protect and maintain environmental safety for smarter agriculture demanded by researchers and industrialists. [ABSTRACT FROM AUTHOR]

The mitogen‐activated protein kinase (MAPK) pathway is an important signalling event associated with every aspect of plant growth, development, yield, abiotic and biotic stress adaptation. Being a central metabolic pathway, it is a vital target for manipulation for crop improvement. In this review, we have summarised recent advancements in understanding involvement of MAPK signalling in modulating abiotic and biotic stress tolerance, architecture and yield of plants. MAPK signalling cross talks with reactive oxygen species (ROS) and abscisic acid (ABA) signalling events in bringing about abiotic stress adaptation in plants. The intricate involvement of MAPK pathway with plant's pathogen defence ability has also been identified. Further, recent research findings point towards participation of MAPK signalling in shaping plant architecture and yield. These make MAPK pathway an important target for crop improvement and we discuss here various strategies to tweak MAPK signalling components for designing future crops with improved physiology and phenotypes. Summary Statement: To the best of our knowledge, the proposed review article is first of its kind which has comprehensively discussed involvement of mitogen‐activated protein kinase (MAPK) signalling cascade in abiotic and biotic stress tolerance as well as plant development and crop yield in a single article. Additionally, one of the novel features of this review is that it has also discussed the ways to manipulate the MAPK signalling components for designing crops for improved stress resilience as well as yield. Climate change, rapid decline in lands arable lands and population explosion necessitates revisiting the role of a very important central metabolic pathway (i.e., MAPK signalling module) for achieving crop improvement and stress adaption in plants and in our present review; we have tried to address it to the best possible extent. [ABSTRACT FROM AUTHOR]

Organic farming in extensive production regions, such as the Canadian prairies have a particularly difficult challenge of replenishing soil reserves of phosphorus (P). Organic grains are exported off the farm while resupply of lost P is difficult due to limited availability of animal manures and low solubility of rock organic fertilizers. As a result, many organic farms on the prairies are deficient in plantavailable P, leading to productivity breakdown. A portion of the solution may involve crop genetic improvement. A hypothetical 'catch and release' wheat ideotype for organic production systems is proposed to (i) enhance P uptake and use efficiency but (ii) translocate less P from the vegetative biomass into the grain. Root traits that would improve P uptake efficiency from less-available P pools under organic production are explored. The need to understand and classify 'phosphorus use efficiency' using appropriate indices for organic production is considered, as well as the appropriate efficiency indices for use if genetically selecting for the proposed ideotype. The implications for low seed P and high vegetative P are considered from a crop physiology, environmental, and human nutrition standpoint; considerations that are imperative for future feasibility of the ideotype. [ABSTRACT FROM AUTHOR]

The evapotranspiration of potato, corn and pea crops in the central region of Boyacá (Colombia) is analyzed under standard conditions and under hydric stress to determine water requirements and optimal planting calendars according to water balances. The study included the collection and purification of information that has a greater impact on these phenomena such as climatological variables, crop physiology and soil types; Mathematical models that describe evapotranspiration and water needs were designed and adjusted, which were implemented computationally through the simulation of all possible crops under study in the analysis period from 1967 to 2019. As results, critical periods were determined and optimal planting dates were established for each crop. [ABSTRACT FROM AUTHOR]

Wheat is one of the most widely consumed grains in the world and improving its yield, especially under severe climate conditions, is of great importance to world food security. Phenotyping methods can evaluate plants according to their different traits, such as yield and growth characteristics. Assessing the vertical stand structure of plants can provide valuable information about plant productivity and processes, mainly if this trait can be tracked throughout the plant's growth. Light Detection And Ranging (LiDAR) is a method capable of gathering three-dimensional data from wheat field trials and is potentially suitable for providing non-destructive, high-throughput estimations of the vertical stand structure of plants. The current study considers LiDAR and focuses on investigating the effects of sub-sampling plot data and data collection parameters on the canopy vertical profile (CVP). The CVP is a normalized, ground-referenced histogram of LiDAR point cloud data representing a plot or other spatial domain. The effects of sub-sampling of plot data, the angular field of view (FOV) of the LiDAR and LiDAR scan line orientation on the CVP were investigated. Analysis of spatial sub-sampling effects on CVP showed that at least 144000 random points (600 scan lines) or an area equivalent to three plants along the row were adequate to characterize the overall CVP of the aggregate plot. A comparison of CVPs obtained from LiDAR data for different FOV showed that CVPs varied with the angular range of the LiDAR data, with narrow ranges having a larger proportion of returns in the upper canopy and a lower proportion of returns in the lower part of the canopy. These findings will be necessary to establish minimum plot and sample sizes and compare data from studies where scan direction or field of view differ. These advancements will aid in making comparisons and inform best practices for using close-range LiDAR in phenotypic studies in crop breeding and physiology research. [ABSTRACT FROM AUTHOR]

Grain yield improvement in globally important staple crops is critical in the coming decades if production is to keep pace with growing demand; so there is increasing interest in understanding and manipulating plant growth and developmental traits for better crop productivity. However, this is confounded by complex cross-scale feedback regulations and a limited ability to evaluate the consequences of manipulation on crop production. Plant/crop modelling could hold the key to deepening our understanding of dynamic trait–crop–environment interactions and predictive capabilities for supporting genetic manipulation. Using photosynthesis and crop growth as an example, this review summarises past and present experimental and modelling work, bringing about a model-guided crop improvement thrust, encompassing research into: (1) advancing cross-scale plant/crop modelling that connects across biological scales of organisation using a trait dissection–integration modelling principle; (2) improving the reliability of predicted molecular–trait–crop–environment system dynamics with experimental validation; and (3) innovative model application in synergy with cross-scale experimentation to evaluate G × M × E and predict yield outcomes of genetic intervention (or lack of it) for strategising further molecular and breeding efforts. The possible future roles of cross-scale plant/crop modelling in maximising crop improvement are discussed. Significant improvements in the grain yield of globally important staple crops will be required in the coming decades, prompting genetic manipulation of plants for gains. But this path is impeded by limited understanding of molecular- and crop-scale interactions and insufficient field testing. To overcome these challenges, a model-guided crop improvement strategy can be employed, which capitalise on emerging cross-scale plant/crop models for unpacking complex agronomic traits and evaluating genetic manipulation targets, adding significant value to yield improvement efforts. [ABSTRACT FROM AUTHOR]

Gamma-aminobutyric acid (GABA) is a non-protein amino acid known for its role in the nervous system of animals. However, research has also revealed its presence and function in plants recently. In plants, GABA is a signal molecule involved in multiple physiological processes, including stress response, growth, and development. This review aims to present a thorough summary of the current knowledge regarding the role of GABA in plants. We begin by discussing the biosynthesis and transport of GABA in plants, followed by a detailed examination of its signaling mechanisms. Additionally, we explore GABA's potential roles in various plant physiological processes, such as abiotic stress response, and its potential application in horticultural plants. Finally, we highlight current challenges and future directions for research in this area. Overall, this review offers a comprehensive understanding of the significance of GABA in plants and its potential implications for plant physiology and crop improvement. [ABSTRACT FROM AUTHOR]

The long‐term dynamics of the transcriptome under natural field conditions remain unclear. We conducted comprehensive gene expression analyses of rice leaves and roots grown under natural field conditions for a long period, from the tillering stage to the ripening stage. In this experiment, changes in the transcriptome were captured in relation to microclimatic parameters, particularly potential evaporation (Ep), which is a multiple meteorological factor and acts as an indicator of transpirational demand. The results indicated that many genes were regulated by changes in temperature and Ep in both leaves and roots. Furthermore, the correlation between gene expression and meteorological factors differed significantly between the vegetative and reproductive stages. Since Ep triggers transpiration, we analyzed aquaporin gene expression, which is responsible for water transport, and found that many aquaporin genes in leaves were positively correlated with Ep throughout the growth period, whereas in roots, two plasma membrane intrinsic aquaporins, PIP2;4 and PIP2;5 were strongly correlated with Ep during reproductive growth. Other genes closely related to productivity, such as those involved in nutrient absorption and photosynthesis, exhibited different responses to meteorological factors at different growth stages. The stage‐dependent shift in the microclimate response provides an important perspective on crop physiology in light of climate change. [ABSTRACT FROM AUTHOR]

Context: In the malting industry, the low protein content of barley grains is a major issue. A useful strategy to overcome this problem is to complement the initial fertilisation with a foliar application of nitrogen (N) near anthesis. Aims: This study aimed to advance knowledge of the metabolic adjustments displayed by plants grown under common management practices in response to foliar N fertilisation at anthesis. Methods: Field experiments with two different rates of foliar N application near anthesis were performed at three commercial sites under the common practice of each farmer. Key results: Grain protein content increased upon foliar fertilisation in all sites without affecting leaf senescence or N remobilisation efficiency. Barley plants also showed a rapid assimilation of the N applied at anthesis, increasing the leaf N organic pools and the global phloem amino acid mobilisation during grain filling. These results could be attributed to the increase in the gene expression of glutamine synthetase 1 and two amino acid transporters (HvAAP6 and HvAAP7). Conclusions: Foliar N applied was rapidly assimilated and exported with high efficiency to the grain with no negative impact over the contribution of N from vegetative organs. Furthermore, phloem N contribution was shown to be of major importance for grain protein content. Implications: Foliar fertilisation near anthesis is an efficient strategy to correct grain protein content to meet maltsters' requirements because it did not affect pre-assimilated N remobilisation, and was useful under the different nutrient availabilities explored here (N sufficiency, N deficiency and sulfur deficiency). Foliar fertilisation near anthesis was an effective strategy to correct grain protein content and meet malting requirements. This was possible because this strategy did not decrease the remobilisation of pre-assimilated nitrogen, and was useful under the different nutrient availabilities explored here. In addition, our results showed that the contribution of phloem nitrogen was of great importance in determining grain protein content. [ABSTRACT FROM AUTHOR]

Source-sink relationships and the management of carbon partitioning among sinks in plants help us to understand crop physiology and yield limiting issues. The effect of variable leaf fruit ratio alone or in combination with girdling on the yield and fruit quality performance of nectarine peach cv. Silver King was analysed. With increasing leaf fruit ratio alone or in conjunction with girdling, the greatest leaf nutrients, such as N, P, K, Ca, and Mg, decreased. The fruit yield decreased linearly as the leaf fruit ratio increased and the lowest yield was reported with the leaf fruit ratio of 50:1 plus girdling half the bark. However, the fruit quality in terms of fruit size and weight were maximum when the leaf fruit ratio was 40:1 and half the bark was girdled. Other fruit quality indicators such as total soluble solids, total sugars, and sugar acid ratio were highest when the leaf fruit ratio was 50:1 coupled with girdling half the bark. The treatment with the lowest titratable acidity was leaf fruit ratio 40:1 + girdling half the bark, followed by leaf fruit ratio 40:1 + girdling half the bark. When compared to control, all of the leaf fruit ratio treatments alone or in combination with girdling half the bark advanced the harvest date by 1–4 days recording earliest harvest, with leaf fruit ratio 50:1 plus girdling half the bark. Overall, leaf fruit ratios of 40:1 combined with girdling half the bark and leaf fruit ratios of 50:1 combined with girdling half the bark were determined to be acceptable for producing high-quality Silver King nectarine. [ABSTRACT FROM AUTHOR]

This study aimed to characterise the specific phenotypic responses and the sensitivity of photosynthetic parameters to progressive drought in modern wheat genotypes. In pot experiments, we tested eight wheat genotypes (Triticum sp.) that differed in ploidy level and country of origin. Water stress was simulated by the restriction of irrigation, which led to a decreased leaf relative water content of up to 70%. During gradual dehydration, changes in the structure and function of photosystem II (PSII) were analysed using the fluorescence parameters derived from fast fluorescence kinetics (OJIP transient). The results indicated that a group of JIP test-based parameters demonstrated sensitivity to drought, including genotype-specific responses. Severe drought stress led to a decrease in the photochemical efficiency of PSII (Fv/Fm), a reduction in the number of active PSII reaction centers (RC/ABS) and a decrease in parameters, indicating overall photochemical performance at the PSII level (performance indices PIabs and PItot). These findings demonstrate that the approaches used in our experiments were useful and reliable in monitoring the physiological responses of individual varieties of wheat exposed to stress conditions, and they have application potential as selection criteria in crop breeding. The contribution of the high-temperature effects on the photochemical responses under water deficit conditions is also discussed.

Plant growth and crop yield are essentially determined by photosynthesis when considering carbon dioxide (CO2) availability. CO2 diffusion inside a leaf is one of the factors that dictate the CO2 concentrations in chloroplasts. Carbonic anhydrases (CAs) are zinc-containing enzymes that interconvert CO2 and bicarbonate ions (HCO3−), which, consequently, affect CO2 diffusion and thus play a fundamental role in all photosynthetic organisms. Recently, the great progress in the research in this field has immensely contributed to our understanding of the function of the β-type CAs; however, the analysis of α-type CAs in plants is still in its infancy. In this study, we identified and characterized the OsαCA1 gene in rice via the analysis of OsαCAs expression in flag leaves and the subcellular localization of its encoding protein. OsαCA1 encodes an α-type CA, whose protein is located in chloroplasts with a high abundance in photosynthetic tissues, including flag leaves, mature leaves, and panicles. OsαCA1 deficiency caused a significant reduction in assimilation rate, biomass accumulation, and grain yield. The growth and photosynthetic defects of the OsαCA1 mutant were attributable to the restricted CO2 supply at the chloroplast carboxylation sites, which could be partially rescued by the application of an elevated concentration of CO2 but not that of HCO3−. Furthermore, we have provided evidence that OsαCA1 positively regulates water use efficiency (WUE) in rice. In summary, our results reveal that the function of OsαCA1 is integral to rice photosynthesis and yield potential, underscoring the importance of α-type CAs in determining plant physiology and crop yield and providing genetic resources and new ideas for breeding high-yielding rice varieties. [ABSTRACT FROM AUTHOR]

Fluctuating light (FL) and drought stress usually occur concomitantly. However, whether drought stress affects photosynthetic performance under FL remains unknown. Here, we measured gas exchange, chlorophyll fluorescence, and P700 redox state under FL in drought-stressed tomato (Solanum lycopersicum) seedlings. Drought stress significantly delayed the induction kinetics of stomatal and mesophyll conductances after transition from low to high light and thus delayed photosynthetic induction under FL. Therefore, drought stress exacerbated the loss of carbon gain under FL. Furthermore, restriction of CO 2 fixation under drought stress aggravated the over-reduction of photosystem I (PSI) upon transition from low to high light. The resulting stronger FL-induced PSI photoinhibition significantly suppressed linear electron flow and PSI photoprotection. These results indicated that drought stress not only caused a larger loss of carbon gain under FL but also accelerated FL-induced photoinhibition of PSI. Furthermore, drought stress enhanced relative cyclic electron flow in FL, which partially compensated for restricted CO 2 fixation and thus favored PSI photoprotection under FL. To our knowledge, we here show new insight into how drought stress affects photosynthetic performance under FL. • We examine the effect of drought stress on dynamic photosynthesis in tomato. • Drought stress decreases mesophyll conductance during light induction. • Drought stress causes photosynthetic depression under fluctuating light. • Drought stress aggravates photoinhibition of photosystem I under fluctuating light. • Drought stress largely affects crop physiology under fluctuating light. [ABSTRACT FROM AUTHOR]

A comprehensive study on both the eco-physiological and productive response of potatoes to dynamic deficit irrigation is lacking. Therefore, the aim was to study, over two growing seasons and on two potato cultivars—Arinda and Timate, the effects of five irrigation regimes (I0–dry control, I1—irrigated control, I2—supply 100% of the maximum evapotranspiration—ETm from tuber initiation up to 50% of tuber growth and 0% ETm from 50% to the end of tuber growth, I3—supply 100% of ETm from tuber initiation up to 50% of tuber growth and 50% ETm from 50% to the end of tuber growth, I4—supply 100% of ETm from tuber initiation up to 50% of tuber growth and 75% ETm from 50% to the end of tuber growth) simultaneously on the crop physiology (via chlorophyll fluorescence and leaf gas exchange traits), above-ground biomass yield, tuber yield and its components, irrigation water use efficiency (IWUE), source/sink ratio and tubers' dry matter content. Regardless of cultivars and seasons, in I3 and I4 for eco-physiological and productive traits, values comparable with I1 were found. Compared to I1, I2 reduced tuber yield by about 18% but increased the IWUE by about 110%, saving a high amount of irrigation water (about 1500 m3 ha−1 per season). Arinda appeared more susceptible than Timate to water deficit in the second part of tuber growth, namely I2, from an eco-physiological point of view, but no differences between cultivars were found from a productive point of view. It was possible to effectively apply dynamic deficit irrigation to save irrigation water without compromising yields strongly. [ABSTRACT FROM AUTHOR]

Insolation and precipitation instability associated with climate change affects plant development patterns and water demand. The potato root system and soil properties lead to water vulnerability, impacting crop yield. Regarding potato physiology, plants stop growing when the root depth stabilizes, and then the tuberization period begins. Since this moment, water supply is required. Consequently, an approach based on plant physiology may enable farmers to detect the beginning of the irrigation period precisely. Remote sensing is a fast and precise method for obtaining surface information using non-invasive data collection. The database comprises root depth (RD) and plant height (H) data collected during 2019, 2020, and 2021. This research aims to develop a dynamic approach based on remote sensing and crop physiology to accurately determine the beginning of the tuberization period, called here the irrigation critical point (ICP). The results indicate a high correlation between RD and H (>0.85) which is independent of in-field soil and relief variations > 0.95). Further, plant growth rate corroborates the correlation results with decreasing patterns in time (R2 > 0.80), independent of environmental variations. In short, it was possible to determine the ICP based on the crop growth dynamics, independently of climate variations, field placement, or irrigation system. [ABSTRACT FROM AUTHOR]

Changes in plant metabolism due to water deficit combined with other stresses, such as high irradiance and high temperatures, cause damage to the physiology and development of crops, which can lead to significant yield losses. The aim of this study was to determine the potential of potassium phosphite (PP) to induce tolerance to water deficit combined with high irradiance in soybean plants. The experiment was carried out in an acclimatized growth chamber. Soybean plants, upon reaching the R1 developmental stage, received the following treatments: PP application (0 L ha−1–control; 0.6 L ha−1 PP; and 1.2 L ha−1 PP), two levels of PAR irradiance (650 µmol m−2 s−1–control; and 1500 µmol m−2 s−1–high irradiance (HI)), and three water availability levels (90% of field capacity (FC), and water deficit at 40% FC and 50% FC). The treatments were maintained for 12 days. The PP increased the photosynthetic rate of plants submitted to a dosage of 1.2 L ha−1 and stresses of 50% FC + HI. PP also decreased the intensity of lipid peroxidation, and rate of electrolyte leakage, which suggests stability of cell membranes. These responses may have occurred due to the activation of the antioxidant enzymes superoxide dismutase and peroxidase. Furthermore, the application of PP increased the proline concentrations, suggesting osmotic adjustment in response to stress. These results provide the first record of PP-induced tolerance in plants under combined water and HI stresses. PP proves to be a potential alternative method to reduce the harmful effects caused by the combined stresses of water deficit and high irradiance in soybean. [ABSTRACT FROM AUTHOR]