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Free proline, termed proline, is a biomarker used for diagnosing drought stress in plants. A previously developed proline–ninhydrin reaction-based paper sensor could quickly and easily detect proline, but it was limited by low sensitivity. In this study, we developed an enclosed multilayer paper-based microfluidic sensor with high sensitivity for the quantitative detection of proline in plants. The multilayer paper-based sensor was manufactured using simple wax printing and origami methods, and contained an internal mixing channel to allow good mixing of the proline with ninhydrin, increasing the proline–ninhydrin reactivity and providing accurate and sensitive proline detection. By preloading ninhydrin onto the sample loading area, uniform coloration of the sensing window was achieved, allowing quantitative analysis of various proline concentrations using a constant reaction time. Only the sensing window and sample loading area were exposed to limit sample evaporation and contamination from the external environment. The LOD of the fabricated sensor was 23 μM, which is approximately 29-fold lower than that of the previously proposed paper sensor (657 μM). Samples were extracted from A. thaliana plants subjected to drought stress for proline detection. The proline concentrations measured using the developed paper sensor and a spectrophotometric method were not statistically significant at a confidence level of 95%. Therefore, the developed sensor can be applied to measure proline concentrations precisely in the field with a low detection limit. The developed paper-based sensor can be used to detect the early stages of drought in plants and thus improve crop productivity. Image 1 • An enclosed multilayer paper-based microfluidic sensor for proline quantification is manufactured. • The enclosed multilayer sensor structure avoids sample evaporation and contamination. • The sensor detects proline with a LOD of 23 μM. • The sensor is suitable for the early detection of drought stress in plants. • The measured proline concentration is similar to that measured by spectrometry. [ABSTRACT FROM AUTHOR]

Drought stress of crops is an important factor affecting their yield and sustainable agricultural development. Accurate diagnosis of crop drought stress is the basis for improving water resource utilization. Imaging technology can quickly, automatically, non-destructively, accurately acquire and analyze the phenotype characteristics of crops, providing a powerful new tool for crop science research. This paper focuses on the review of phenotype imaging analysis techniques for crop drought stress diagnosis. First, the single imaging technique for crop drought stress diagnosis was introduced, and then we introduced the fusion imaging technique for crop drought stress diagnosis. In the aspect of single imaging technology introduction, firstly, the principles of six phenotype imaging techniques including RGB imaging, 3D imaging, near-infrared imaging, hyperspectral imaging, chlorophyll fluorescence imaging and thermal imaging are introduced in this paper, and then we introduced research progress of the single imaging technology in crop drought stress phenotype analysis, beside the research achievements in crop drought stress in recent years were further summarized. Finally, the imaging technology was summarized and prospected at the end of each imaging technology introduction. In the fusion imaging technology of crop drought stress, this paper first summarized the research results of the automatic comprehensive phenotype imaging analysis platform of crop drought stress in recent years, and then summarized and analyzed the research of different fusion imaging methods, analyzed their advantages and disadvantages, and prospected the future research direction of fusion imaging technology in the end. With the horizontal and vertical comparative analysis of the research results of a single imaging technology, we found that RGB imaging technology has the lowest application cost and the most extensive application range, but the lowest accuracy. The 3D imaging solves the problem of crop occlusion in RGB imaging, improves the accuracy, and is widely used in high-throughput phenotype extraction platforms. The information on crop phenotype parameters can be obtained by near-infrared spectroscopy, chlorophyll fluorescence and hyperspectral imaging in a fast and non-destructive way. Among them, the application scope of NIR imaging is limited due to its limited ability to obtain phenotype information and relatively high cost. Chlorophyll fluorescence and hyperspectral imaging are better at obtaining physiological and biochemical parameters of crops, and are widely used in the fusion of imaging methods. Thermal images obtained by infrared thermal imaging are often used to obtain crop physiological parameters, and are also combined with visible light images for phenotype extraction. In the meantime, the method of obtaining crop phenotype by using the fusion of multiple imaging technologies has the advantages of different imaging technologies, which can effectively avoid the defects of a single imaging technology and make up for the deficiencies of obtaining single imaging phenotype parameters, so as to reflect the crop growth status more accurately and efficiently. More accurate feature extraction can be achieved by integrating various image information obtained by various imaging technologies and using artificial intelligence methods for integrated image processing. The use of fusion imaging technology to obtain crop phenotypes will be one of the important directions of crop drought stress phenotypes extraction in the future. Finally, according to the current development situation, future research on phenotypic imaging technology for crop drought stress diagnosis prospects, including the development of new devices and the combination of new artificial intelligence algorithms. [ABSTRACT FROM AUTHOR]

Climate change is raising concerns about how forests will respond to extreme droughts, heat waves and their co-occurrence. In this greenhouse study, we tested how carbon and water relations relate to seedling growth and mortality of northeastern US trees during and after extreme drought, warming, and combined drought and warming. We compared the response of our focal species red spruce (Picea rubens Sarg.) with a common associate (paper birch, Betula papyrifera Marsh.) and a species expected to increase abundance in this region with climate change (northern red oak, Quercus rubra L.). We tracked growth and mortality, photosynthesis and water use of 216 seedlings of these species through a treatment and a recovery year. Each red spruce seedling was planted in containers either alone or with another seedling to simulate potential competition, and the seedlings were exposed to combinations of drought (irrigated, 15-d 'short' or 30-d 'long') and temperature (ambient or 16 days at +3.5 °C daily maximum) treatments. We found dominant effects of the drought reducing photosynthesis, midday water potential, and growth of spruce and birch, but that oak showed considerable resistance to drought stress. The effects of planting seedlings together were moderate and likely due to competition for limited water. Despite high temperatures reducing photosynthesis for all species, the warming imposed in this study minorly impacted growth only for oak in the recovery year. Overall, we found that the diverse water-use strategies employed by the species in our study related to their growth and recovery following drought stress. This study provides physiological evidence to support the prediction that native species to this region like red spruce and paper birch are susceptible to future climate extremes that may favor other species like northern red oak, leading to potential impacts on tree community dynamics under climate change. [ABSTRACT FROM AUTHOR]

[Objective) The present paper aimed to obtain the complete sequence of SsREMO-la gene, conduct tissue-specific expression, qPCR expression analysis, sub-cellular localization study, and the phenotypic changes of Arabidopsis thaliana with SsREMO-la gene transfer and the expression pattern of CAT-1 gene. (Method) The complete sequence of SsREMO-la gene was obtained by PCR, purification, cloning and sequencing from Hainan sugarcane wild species (Sp-24). Drought stress was applied to the normal growth of the seedlings. Young leaves, roots and stems at 0, 1, 2, 3, 4 and 5 days after the stress treatment were collected for tissue-specific expression analysis and qPCR analysis. The tissue location and function of SsREMO-1a were analyzed by tobacco sub-cellular mapping and gene transformation techniques. PB1221-SSREMO-1a-GFP fusion expression vector was constructed and transformed into tobacco for cell localization analysis. The over-ex- pression vector pCAMBIA 1304-SsREMO-la was constructed, and SsREMO-1a was introduced into A. thaliana by agrobacterium transformation. The phenotypes of plants at 0, 1, 2, 3, 4 and 5 days after drought stress and the expression of CAT-1 gene were observed. [Result] The full length of SsREMO-1a gene was 738 bp, and the open code frame (ORF) was 564 bp, encoding 187 amino acids. Tissue-specific expression showed that SsREMO-1a was expressed in roots, stems and leaves. qPCR results showed that the gene was induced by drought stress and showed significantly up-regulated expression. The results of sub-cellular localization showed that SsREMO-1a protein was localized on the cell membrane. A total of 11 transgenic A. thaliana lines were obtained, and the drought resistance identification showed that the transgenic plants could improve the drought resistance of the plants. The expression of CAT-1 gene in transgenic plants was significantly in- creased. [Conclusion] SsREMO-1a can improve the drought resistance of plants and regulate CAT-1 gene to some extent. [ABSTRACT FROM AUTHOR]

Context: Cannabis is a herbaceous annual plant that belongs to the Cannabaceae family, which is used in the production of fibre, paper, oil and pharmaceutical products. Aims: The aim of this study was to identify drought-tolerant ecotypes and medicinal and industrial populations. Methods: Due to the medicinal and industrial importance of cannabis, 12 cannabis ecotypes were collected from different regions of Iran. Then, their agronomic and phytochemical characteristics were evaluated under different soil moisture conditions. Key results: The soil moisture levels had significant effects (P < 0.01) on the studied traits except for the 1000 seed weight. Based on duration of the growth period, the Tabas and Dasht-e-Moghan ecotypes were identified as early and late maturing ecotypes, respectively. Also, the highest stem dry weight and stem height/diameter ratio and the lowest seed yield were related to the Dasht-e-Moghan ecotype, which is valuable for fibre production. Based on seed yield (relative reduction) and some tolerance indexes, the Tabas and Tabrize ecotypes were shown to be the most tolerant and sensitive ecotypes, respectively. As soil moisture decreased, tetrahydrocannabinol levels increased and cannabidiol levels decreased. The highest amount of tetrahydrocannabinol was related to the Qom ecotype at 50% soil moisture and the highest amount of cannabidiol was related to the Rasht ecotype at 100% soil moisture. Conclusions: Generally, these ecotypes had different responses to soil moisture. Some ecotypes were valuable in terms of the production of pharmaceutical metabolites and some in terms of fibre production. Implications: Tolerant and sensitive ecotypes might be considered in production and also breeding programs. Cannabis is a herbaceous annual plant that belongs to the Cannabaceae family, and is used in the production of fibre, paper and oil. This plant has been used for the treatment of rheumatism, epilepsy, asthma, skin burns, gastrointestinal activity, osteoporosis, schizophrenia, cardiovascular disorders, cancer and metabolic syndrome-related disorders. Generally, our findings showed that these ecotypes had different responses to soil moisture, and some ecotypes were valuable in terms of the production of pharmaceutical metabolites and some in terms of fibre production. [ABSTRACT FROM AUTHOR]

The growth environment of prickly pepper without thorns in dry land is harsh, and the survival rate is low, which limits its planting scale and yield. In order to improve the survival rate of prickly pepper without thorns in dry land, this paper studies the cultivation techniques of prickly pepper without thorns under drought stress through root treatment, planting area coverage, land preparation, etc. The experiments show that: the methods of root treatment > planting area cover > land preparation improved the survival rate of prickly pepper without thorns under drought stress, which had great significance in promoting the development of Tianshui industry. [ABSTRACT FROM AUTHOR]

Atriplex canescens is widely cultivated as drought and salt-tolerant fodder in arid regions of Northwest China, which is used for photoremediation of degraded land and soil and water conservation. To explore the growth performance of A. canescens when exposed to drought and salt stress, seedlings were treated with a range of drought stress (WC1: 75 ± 3.6%, WC2: 49 ± 2.9% and WC3: 27 ± 2.5% of soil water content) and the corresponding drought stress with additional sodium salt supplementation (NaCl:Na2SO4 = 1:1 with the total concentration of Na+ set to 150 mM). The findings of this paper indicated that moderate sodium salt could stimulate the growth of A. canescens and effectively alleviate the deleterious impact of drought stress by increasing the turgor potential (ψt) and relative water content (RWC) and decreasing the leaf water osmotic potential (ψs). Furthermore, the photosynthetic capacity was improved and the negative effects of drought stress on photosystem II (PSII) were mitigated. The extra 150 mM sodium salt also markedly increased the contribution of Na+ to ψs and the contribution of betaine to ψs. In summary, these results indicate that A. canescens can adapt to drought stress by accumulating enough Na+ for osmotic adjustment (OA). Additionally, this paper is aimed to provide a fundamental basis for the utilization and cultivation of A. canescens as a favored pasture crop in the Qaidam basin, thus increasing the ecological and environmental benefits for arid regions worldwide. [ABSTRACT FROM AUTHOR]

【Objective】The paper aims to explore the effect of drought stress on endogenous hormones in Camellia reticulata and the molecular mechanism of plant hormone signal transduction pathway responding to drought stress.【Method】The pot seedlings of half-one-year-old wild C.reticulata were used as experimental materials, and 20% PEG-6000 was used to simulate severe drought stress. The contents of auxin (IAA), zeatin nucleoside (ZR), gibberellin (GA) and abscisic acid (ABA) in roots and leaves of C.reticulata at 0, 24, 72 hours and 48 hours after rewater (re48 hours) under drought stress, and at the same time, the leaves were sequenced by transcriptome to screen differential genes.【Result】Under drought stress, the endogenous hormones in C.reticulata were all affected. The IAA content in leaves first increased and then decreased and then increased after rehydration, while the IAA content in roots continued to decrease and did not recover after rewater. The change trend of ZR content in leaves was the same as IAA, while that in roots was opposite to that in leaves.GA content in leaves increased continuously during stress and rewater, while GA content in roots increased during stress and decreased after rewater. The change trend of ABA content in leaves was similar to IAA, and ABA content in roots continued to increase during stress, and then decreased after rewater, which was similar to the change trend of GA content in roots.A total of 33 349 differentially expressed genes were screened from the transcriptome sequencing results of C.reticulata, which were significantly enriched in plant hormone transduction, phenylpropionic acid biosynthesis, carotenoid biosynthesis, porphyrin and chlorophyll metabolism, photosynthesis and other pathways at four time points. Drought stress induced the expression of 46 differential genes in plant hormone signal transduction pathway. Four gene modules were identified by weighted gene co-expression network analysis (WGCNA), and the transcription group was correlated with the contents of the four hormones. Two key gene modules with high correlation with hormone response were screened, including 2769 and 2502 genes respectively. The top 5% genes in the key modules were selected for co-expression analysis, and six key genes (SDH1-1, PETC, VHA-A3, FtsH, chlD, TL17) and five transcription factors (IAA9, NAC, Trihelix, SWI/SNF, NF-YB) were obtained.【Conclusion】Drought stress affects the changes of endogenous hormone content and the expression of related pathway genes. In the study, two co-expression modules closely related to drought stress response are also identified. It is found that genes such as SDH1-1, PETC, VHA-A3, FtsH, chlD, TL17 and transcription factors such as IAA9, NAC, Trihelix, SWI/SNF, NF-YB play an important role in the response of endogenous hormones in C.reticulata under drought stress. [ABSTRACT FROM AUTHOR]

In order to explore the effects of exogenous salicylic acid soaking treatment on millet germination and seedling growth under PEG stress, Jizajinmiao NO. 1 millet was used as the test material, and the effects of five salicylic acid concentrations (0, 50, 100, 150, and 200 mg/L) on the seed germination process and seedling growth of millet under 20% PEG treatment were determined by Petri dish filter paper method. The results showed that with the increase of salicylic acid concentration, the germination rate, germination potential, germination index, and vigor index of millet seeds showed a trend of first increasing and then decreasing, and when the concentration of salicylic acid was 150 mg/L, all the indexes reached the maximum, which were 95.33%, 90.67%, 1.12, and 39.22, respectively, which were 1.22, 1.30, 1.36, and 2.12 times that of the distilled water control group (the alicylic acid concentration was 0 mg/L). The germination rate, germination potential, germination index, and vigor index of millet seeds under PEG stress were higher than those of the PEG control treatment (the salicylic acid concentration was 0 mg/L and 20% PEG solution was added), the salicylate concentration increased first and then decreased with the increase of salicylate concentration, and the indexes reached the maximum when the salicylic acid concentration was 150 mg/L. With the increase of salicylic acid concentration, root length, plant height, fresh weight, chlorophyll content, proline content, and peroxidase (POD) activity of foxtail millet seedlings increased first and then decreased, while the relative conductivity and malondialdehyde (MDA) content showed a trend of first decreasing and then increasing. The results showed that the salicylic acid had a significant effect on seed germination and seedling growth of millet under drought stress, and the better treatment effect was achieved when the concentration of salicylic acid was 150 mg/L. [ABSTRACT FROM AUTHOR]

In order to understand the differences in drought resistance at the seedling stage of P. humilis, provide scientific basis for the introduction of P. humilis varieties and the selection and cultivation of drought resistant varieties, in this paper, the plant height was measured after natural drought stress treatment for 15 and 30 days, and normal watering was used as the control. The relative water content, SPAD value, and other physiological indexes of young leaves of six P. humilis varieties including Nondada 5, Nongda 7, Jingou 1, Nongda 4, Ningou 2, and Nonda 6 under the same drought stress were measured by the extremely drought environment simulated by PEG-6000 solution and water was taken as the control. The results showed that under the natural drought conditions, the plant height of the P. humilis varieties decreased significantly compared with that of the control. Under the drought stress of PEG-6000, the soluble protein, relative water content of leaves, relative chlorophyll SPAD value, and SOD activity of different P. humilis varieties showed a downward trend compared with those of the control. The content of malondialdehyde, proline, and soluble sugars, POD activity all showed an upward trend. Using the comprehensive evaluation of the membership function value of the drought resistance index for P. humilis, it was concluded that the drought resistance of P. humilis varieties was ranked from strong to weak as Nongda 5, Nongda 7, Jingou 1, Nongda 4, Ningou 2 and Nongda 6. So, the Nongda 5 and Nongda 7 had strong drought resistance and good adaptability, and were suitable to be the main promoted varieties in Ningxia. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to analyze the impact of varying degrees of drought stress treatments on the physiological parameters of Indigofera pseudotinctoria, preliminarily evaluate the drought-resistant physiological responses of these materials, and provide a foundational reference for the selection and genetic improvement of drought-resistant germplasm in I. pseudotinctoria. [Method] 36 wild J. pseudotinctoria germplasm resources collected in Chongqing area were used as experimental materials. Pot cultivation was used to start drought treatment when 1. pseudotinctoria seedlings grew to the 90th day, and measure the content of osmoregulatory substances, relative water content, and antioxidant enzyme activity in the leaves of I. pseudotinctoria under 0 days of stress (control group CK, the relative soil water content was 80%-85% of the field water capacity), 7 days of stress (moderate drought, soil relative moisture content was 40%-50% of the field water capacity), and 14 days of stress (severe drought, soil relative moisture content was 20%-25% of the field water capacity). Drought resistance coefficients, membership functions and cluster analysis were applied for a comprehensive evaluation of drought resistance. [Result] Under drought stress conditions, we observed a wide variation in physiological responses among the 36 1. pseudotinctoria germplasms, leading to significant differences in their drought resistance capabilities. Comparative analysis of mean values for various parameters showed that, in comparison to the control group, osmotic adjustment substances such as malondialdehyde (MDA), soluble protein (SP), and proline (Pro) increased with the severity of drought. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) exhibited a convex trend as drought severity intensified, while relative water content (RWC) decreased with increasing drought stress. Among the seven parameters measured, peroxidase (POD) activity showed the largest coefficient of variation, while relative water content (RWC) displayed the smallest variation. Using membership function analysis, comprehensive D-value assessment, and cluster analysis, we categorized the drought resistance of the 36 1. pseudotinctoria germplasms into two distinct groups: Drought-resistant (comprising 8 germplasms) and sensitive (comprising 28 germplasms). Further examination of physiological indicators between these two groups revealed that drought-resistant germplasms exhibited higher antioxidant enzyme activity and osmotic adjustment substance Pro content compared to their sensitive counterparts. Conclusion] Under drought stress conditions, the physiological responses of the 36 1. pseudotinctoria germplasm resources displayed significant diversity and variation. Among the 36 1. pseudotinctoria germplasms, 8 germplasms were classified as drought-resistance by a comprehensive evaluation analysis. [ABSTRACT FROM AUTHOR]

Background: Wheat (Triticum aestivum L.) is one of the most widely grown and vital cereal crops, containing a high percentage of basic nutrients such as carbohydrates and proteins. Drought stress is one of the most significant limitations on wheat productivity. Due to climate change influences plant development and growth, physiological processes, grain quality, and yield. Drought stress has elicited a wide range of plant responses, namely physiological and molecular adaptations. Biopriming is one of the recent attempts to combat drought stress. Mitigating the harmful impact of abiotic stresses on crops by deploying extreme-habitat-adapted symbiotic microbes. The purpose of this study was to see how biopriming Triticum aestivum grains affected the effects of inoculating endophytic fungi Aspergillus fumigatus ON307213 isolated from stressed wheat plants in four model agricultural plants (Gemmiza-7, Sids-1, Sakha8, and Giza 168). And its viability in reducing drought stress through the use of phenotypic parameters such as root and shoot fresh and dry weight, shoot and root length, and so on. On a biochemical and physiological level, enzymatic parameters such as catalase and superoxidase dismutase are used. Total phenolics, flavonoids, and photosynthetic pigments are non-enzymatic parameters. Making use of molecular techniques such as reverse transcriptase polymerase chain reaction (RT-PCR). Results: It has been found that using Aspergillus fumigatus as a biological biopriming tool can positively impact wheat plants experiencing drought stress. The total biomass of stressed wheat plants that had been bio-primed rose by more than 40% as compared to wheat plants that had not been bio-primed. A. fumigatus biopriming either increased or decreased the amount of enzymatic and non-enzymatic substances on biochemical scales, aside from the noticeable increase in photosynthetic pigment that occurs in plants that have been bio-primed and stressed. Drought-resistant genes show a biopriming influence in gene expression. Conclusions: This is the first paper to describe the practicality of a. fumigatus biopriming and its effect on minimizing the degrading effects of drought through water limitation. It suggests the potential applications of arid habitat-adapted endophytes in agricultural systems. [ABSTRACT FROM AUTHOR]

Key message: PtrANR1 positively regulates plant drought tolerance by increasing proline level and reducing ROS accumulation. PtrANR1 directly activates PtrAUX1 expression to promote root growth and improve plant drought tolerance. Citrus quality and yield are severely declined under drought stress. To date, the effects of MADS-box family transcription factors (TFs) on plant drought resistance have made some progress. However, whether MADS-box family TFs are associated with citrus drought response has remained unclear. The current paper identified a MADS-box family gene PtrANR1 encoding anthocyanidin reductase from trifoliate orange. PtrANR1 exhibits high identities with ANR1 proteins found in various plants. PtrANR1 possesses two conserved domains known as MADS and kertanin-like domains. PtrANR1 is a nuclear protein which has transactivation activity. A significant induction of PtrANR1 transcript was detected in leaves and roots of trifoliate orange treated with PEG6000 and ABA. Under drought stress, Arabidopsis ectopic overexpressing PtrANR1 exhibited obviously elevated contents of proline, ABA and IAA, better developed root, enhanced antioxidant enzyme activities, as well as notably reduced accumulation of malondialdehyde (MDA) and reactive oxygen species (ROS) compared with WT plants. However, opposite change trends of these physiological indices were detected in PtrANR1 homolog silencing lemon. Furthermore, transgenic Arabidopsis displayed significantly increased expression levels in genes associated with ABA, IAA and proline production, IAA polar transport, ROS elimination and drought response. However, these genes exhibited noticeably decreased transcript levels in PtrANR1 homolog silencing lemon. Moreover, PtrANR1 could increase IAA content and promote root growth by binding to GArG-box in the promoter of PtrAUX1 to activate its transcript. These findings indicated that PtrANR1 had a beneficial impact on plant drought resistance through promoting root development, increasing proline accumulation and scavenging of ROS. [ABSTRACT FROM AUTHOR]

Alfalfa (Medicago sativa L.) plays an important role in livestock production in most regions of the world, but the quantity and quality of alfalfa have been critically affected by drought events in recent years. Thus, quantifying the efficacy of widely used strategies, irrigation methods and fertilization that are aimed at improving drought resistance in alfalfa is a worthy topic that has been addressed in a variety of ways using both field observations and simulation models. Although such strategies play a critical role in climate change adaptation, the global patterns of these strategies in a changing world remain elusive due to regional differences, such as drought features, strategy design and environmental conditions. Thus, by using effect size and statistical analyses, we synthesized three variables, namely, alfalfa yield, water use efficiency (WUE) and crude protein (CP), to examine the efficacy of irrigation methods and fertilization in drought areas based on peer‐reviewed papers from 1990 to 2022. Our results showed that increasing drought stress reduces the alfalfa yield (−34.4%) but can increase the WUE (+13.7%). Both yield and WUE showed a negative relationship with the water deficit, but this phenomenon can be improved by using appropriate irrigation. The yield losses of alfalfa can be offset by implementing a fertilization strategy (+22%) under drought stress, especially for phosphate fertilizer. Overall, our results provide some evidence for the climate change adaptation of alfalfa under drought stress and indicate that fertilization is a more effective adaptation to improve alfalfa drought resistance (both yield and WUE, and yield and CP) than the irrigation method, which shows better performance in improving alfalfa WUE. Our synthesis of the effectiveness of irrigation methods and fertilization on alfalfa drought resistance can be used to develop scientific strategies for climate change adaptation for alfalfa and agriculture under climate change. [ABSTRACT FROM AUTHOR]

Drought is a climate problem which has become a major constraint on crop production and causing social and economic devastation to local farmers worldwide. This climate issue has been the most destructive factors for rice cultivation and therefore requires scientist to be more responsive to this problem. In this study, we investigated the effect of drought stress at an early vegetative stage on plant growth, physiology and root anatomy of a few selected known tolerance rice varieties. Rice seeds were first germinated on moisturized filter papers before transplanted into polybags filled with topsoils. Drought treatment was imposed 4 weeks after transplanting until the first sign of rolled leaves were seen. In this study, drought had no major impact on plant height but reduced dry matter accumulation was seen in all varieties. Drought exposure had also triggered changes in the overall content of chlorophyll but not in the composition of chlorophyll a and b. Meanwhile, plants subject to drought in some parameters had better root morphology and structure compared to normal irrigation, especially in Kuku Belang, Apami and Huma Wangi Lenggong. However, depending on the variety, the responses varied in different order of magnitude. [ABSTRACT FROM AUTHOR]

It is estimated that 40–70%, 80–90% and 50–90% of the conventional macronutrients N, P and K applied to the soil are lost, respectively, resulting in considerable loss of resources. Compared to conventional fertilizers, nanofertilizers have the advantages of controlled release, high nutrient utilization, low cost and relatively low environmental pollution due to their small size (1–100 nm) and high specific surface area. The application of nanofertilizers is an up-and-coming field of agricultural research and is an attractive and economical substitute for common fertilizers which can boost global food productivity sustainably. Foliar fertilization is a popular way to satisfy the needs of higher plants. Because of its small application dose, faster nutrient uptake than soil application and relatively less environmental pollution, foliar fertilization is more popular among plants. It can be seen that nanofertilizers and foliar fertilization are the hotspots of attention at present and that current research on the foliar application of nanofertilizers is not as extensive as that on soil application. Based on this background, this paper provides an overview of various applications of foliar spraying of nanofertilizers in agriculture, including applications in improving crop yield and quality as well as mitigating heavy metal stress, salt stress and drought stress. [ABSTRACT FROM AUTHOR]

Common purslane (Portulaca oleracea) is a halophyte, consumed not only as an edible vegetable but also as a traditional medicine. This plant can adapt to extreme salinity and drought conditions and their effects on plant growth, yield and quality were elucidated, but the effects on seed germination was still unclear. Seed germination is an important stage for establishing P. oleracea seedlings that contribute to plant yield and productivity. Thus, the objective of the present study was to examine the individual effects of salinity and drought stress at different levels on the characteristics of seed germination, which the seeds suffered from −0.22, −0.45, −0.89, and −1.78 MPa osmotic stresses induced by polyethylene glycol (PEG), or from 50, 100, 200, and 400 mM NaCl stresses with equivalent osmotic pressures. The seeds sown in petri dishes containing filter paper layers that were flooded with NaCl or PEG-6000 solutions for the treatments and germination parameters were determined daily for 15 days. Data showed that germination percentage (GP), germination rate (GR), germination energy (GE), and mean germination time (MGT) were significantly decreased with increasing levels of salt and osmotic stresses, suggesting that the salinity and drought stress reduced the germination capability of seeds. Moreover, the seeds maintained germination with PEG osmotic pressure above −0.22 MPa, but not with NaCl concentration greater than 50 mM that induced a similar osmotic pressure, suggesting that the ion toxicity effect on the seed germination might be higher than the osmotic effects. [ABSTRACT FROM AUTHOR]

Legumes play a significant role in the alleviation of food insecurity, maintaining soil fertility, and achieving sustainable crop production under adverse environmental conditions. The increased demand in legume production contemplates that attention on the genetic improvement of these crops through various means such as genetic engineering and mutation breeding should take a centre stage in global agriculture. Therefore, this paper provides a succinct analysis of the currently available literature on morphological and physiological traits in polyploidised leguminous plants to counter the adverse effects of drought stress. The effects of colchicine on various morphological and physiological traits of polyploidised legumes compared to their diploid counterparts were examined. Numerous reports revealed variations in these traits, such as improved root and shoot growth, plant biomass, chloroplastidic content, protein, RNA, and DNA. The differences observed were also associated with the strong relationship between plant ploidy induction and colchicine application. Furthermore, the analysis indicated that polyploidisation remains dose-dependent and may be achievable within a shorter space of time as this antimitotic chemical interferes with chromosome separations in somatic plant cells. The efficiency of this process also depends on the advancement of treatment conditions (in vitro, in vivo, or ex vitro) and the successful regeneration of polyploidised plants for adaptation under drought stress conditions. As such, the improvement in metabolite profile and other essential growth characteristics serves as a clear indication that induced polyploidy needs to be further explored to confer resilience to environmental stress and improve crop yield under drought stress conditions in leguminous plants. [ABSTRACT FROM AUTHOR]

Key message: This paper sheds light on the evolution and expression patterns of MADS genes in Setaria and Panicum virgatum. SiMADS51 and SiMADS64 maybe involved in the ABA-dependent pathway of drought response. The MADS gene family is a key regulatory factor family that controls growth, reproduction, and response to abiotic stress in plants. However, the molecular evolution of this family is rarely reported. Here, a total of 265 MADS genes were identified in Setaria italica (foxtail millet), Setaria viridis (green millet), and Panicum virgatum (switchgrass) and analyzed by bioinformatics, including physicochemical characteristics, subcellular localization, chromosomal position and duplicate, motif distribution, genetic structure, genetic evolvement, and expression patterns. Phylogenetic analysis was used to categorize these genes into M and MIKC types. The distribution of motifs and gene structure were similar for the corresponding types. According to a collinearity study, the MADS genes have been mostly conserved during evolution. The principal cause of their expansion is segmental duplication. However, the MADS gene family tends to shrink in foxtail millet, green millet, and switchgrass. The MADS genes were subjected to purifying selection, but several positive selection sites were also identified in three species. And most of the promoters of MADS genes contain cis-elements related to stress and hormonal response. RNA-seq and quantitative Real-time PCR (qRT-PCR) analysis also were examined. SiMADS genes expression levels are considerably changed in reaction to various treatments, following qRT-PCR analysis. This sheds fresh light on the evolution and expansion of the MADS family in foxtail millet, green millet, and switchgrass, and lays the foundation for further research on their functions. [ABSTRACT FROM AUTHOR]

The Pentatricopeptide repeat (PPR) superfamily is a large gene family in plants that regulates organelle RNA metabolism, which is important for plant growth and development. However, a genome-wide analysis of the PPR gene family and its response to abiotic stress has not been reported for the relict woody plant Liriodendron chinense. In this paper, we identified 650 PPR genes from the L. chinense genome. A phylogenetic analysis showed that the LcPPR genes could roughly be divided into the P and PLS subfamilies. We found that 598 LcPPR genes were widely distributed across 19 chromosomes. An intraspecies synteny analysis indicated that duplicated genes from segmental duplication contributed to the expansion of the LcPPR gene family in the L. chinense genome. In addition, we verified the relative expression of Lchi03277, Lchi06624, Lchi18566, and Lchi23489 in the roots, stems, and leaves and found that all four genes had the highest expression in the leaves. By simulating a drought treatment and quantitative reverse transcription PCR (qRT-PCR) analysis, we confirmed the drought-responsive transcriptional changes in four LcPPR genes, two of which responded to drought stress independent of endogenous ABA biosynthesis. Thus, our study provides a comprehensive analysis of the L. chinense PPR gene family. It contributes to research into their roles in this valuable tree species' growth, development, and stress resistance. [ABSTRACT FROM AUTHOR]

This paper highlights the evolution and impact of the SWAP model (Soil – Water – Atmosphere – Plant), which was initiated by R.A. Feddes and colleagues fifty years ago, in 1974. Since then, the SWAP model has played a crucial role in the advancement of agrohydrology. This paper highlights some major advances that have been made, especially focussing on the last fifteen years. The domain of the SWAP model deals with the simulation of the soil water balance in both unsaturated and saturated conditions. The model solves the Richards equation using the water retention and hydraulic conductivity functions as described by the Van Genuchten – Mualem equations. Bimodal extensions of the Van Genuchten - Mualem relationships have been implemented, as well as modifications near saturation and addressing hysteresis. An important sink term in the Richards equation is root water uptake. Crop development plays an important role in a robust simulation of root water uptake. That is why a link has been made with the dynamic crop growth model WOFOST. Instead of using a prescribed crop development, a distinction between potential and actual crop development is calculated by reducing the potential photosynthesis as a result of water or oxygen stress. Since the early days of SWAP, empirical and macroscopic concepts have been used to simulate root water uptake. Recently two process-based concepts of root water uptake and oxygen stress have also been implemented. Another important sink-source term in the Richards equation is the interaction with artificial drains. In SWAP, drainage can be simulated by either using prescribed or simulated drain heads and simulation of controlled drainage with subirrigation is possible. Finally, we briefly elaborate on three studies using SWAP: water stresses in agriculture in the Netherlands, regional water productivity in China, and controlled drainage with subirrigation. We finish discussing promising developments for the near future. • Advances in soil-vegetation-atmosphere transfer modelling in the SWAP model. • Coupling of soil water dynamics with dynamic crop growth model. • Process-based root water uptake and oxygen uptake functions. • Climate-adaptive drainage with subirrigation. [ABSTRACT FROM AUTHOR]

The two-source energy balance model estimates canopy transpiration (Tr) and soil evaporation (E) traditionally from satellite partitions of remotely sensed land surface temperature (LST) and the Priestley-Taylor equation (TSEB-PT) at seasonal time with limited accuracy. The high spatial–temporal resolution spectral data collected by unmanned aerial vehicles (UAVs) provide valuable opportunity to estimate Tr and E precisely, improve the understanding of the seasonal and the diurnal cycle of evapotranspiration (ET), and timely detect agricultural drought. The UAV data vary in spatial resolution and the uncertainty imposed on the TSEB-PT outcome has thus far not being considered. To address these challenges and prospects, a new energy flux modelling framework based on TSEB-PT for high spatial resolution thermal and multispectral UAV data is proposed in this paper. Diurnal variations of LST in agricultural fields were recorded with a thermal infrared camera installed on an UAV during drought in 2018 and 2019. Observing potato as a test crop, LST , plant biophysical parameters derived from corresponding UAV multispectral data, and meteorological forcing variables were employed as input variables to TSEB-PT. All analyses were conducted at different pixelation of the UAV data to quantify the effect of spatial resolution on the performance. The 1 m spatial resolution produced the highest correlation between Tr modelled by TSEB-PT and measured by sap flow sensors (R2 = 0.80), which was comparable to the 0.06, 0.1, 0.5 and 2 m pixel sizes (R2 = 0.76–0.78) and markedly higher than the lower resolutions of 2 to 24 m (R2 = 0.30–0.72). Modelled Tr was highly and significantly correlated with measured leaf water potential (R2 = 0.81) and stomatal conductance (R2 = 0.74). The computed irrigation requirements (IRs) reflected the field irrigation treatments, ET and conventional irrigation practices in the area with high accuracy. It was also found that using a net primary production model with explicit representation of temperature influences made it possible to distinguish effects of drought vis-a-vis heat stress on crop productivity and water use efficiency. The results showed excellent model performance for retrieving Tr and ET dynamics under drought stress and proved that the proposed remote sensing based TSEB-PT framework at UAV scale is a promising tool for the investigation of plant drought stress and water demand; this is particularly relevant for local and regional irrigations scheduling. [ABSTRACT FROM AUTHOR]

The root system is vital for anchorage, mobilizing water and nutrients and symbiosis with soil microbes, which influence adaptation and crop performance. However, root traits are not widely used in crop variety development because root phenotyping is difficult and there is limited understanding of the genetics of root traits. The available genetic variation and emerging root phenotyping and genotyping technologies present opportunities for integrating root traits in breeding. Selection efficiency for root traits can be enhanced by integrating shovelomics, digital imaging, crop modelling and gene sequencing systems. Therefore, the objectives of this review are to discuss critical root traits and their vital functions, genetic variation present for root traits, opportunities and challenges in root phenotyping and integration of genomic tools in breeding for improved root systems. The information presented in the paper will guide crop breeders in developing a new generation of crop varieties with desirable yield and root traits. [ABSTRACT FROM AUTHOR]

【Objective】The present paper aimed to understand the difference of drought resistance among hybrid soybean varieties, thus to select drought tolerant hybrid soybean varieties.【Method】3 hybrid soybean varieties were used as experimental materials and different concentrations of PEG-6000 solution (5%,10% and 20%) hydroponic model were used to simulate drought stress in soybean seedling stage. To identify the physiological response and drought resistance of 3 hybrid soybeans, chlorophyll content, photosynthetic physiological index, osmotic regulator content and antioxidant enzyme activity of leaves in seedling stage were measured after drought stress. 【Result】With the increasing concentration of PEG-6000 solution, there were significant differences in the related drought resistance indicators of the three hybrid soybeans and the growth of soybean seedlings was gradually significantly inhibited. The chlorophyll content of soybean seedlings was detected, and it was found that with the increase of PEG-6000 solution concentration, its content showed an upward trend, the most significant being dominant Hybrid soybean-A-5. In terms of photosynthetic physiological indexes of soybean seedlings, the variation trends of net photosynthetic rate (Pn), transpiration rate (Tr), intercellular carbon dioxide concentration (Ci) and stomatal conductance (Gs) of leaves of three hybrid soybean seedlings showed significant differences. The response of different soybean varieties to drought stress under different treatment conditions was analyzed. The results showed that soybean seedlings could respond to drought stress through osmoregulation and activating antioxidant defense system was analyzed.The content of each substance changed significantly with the increase of stress degree. There were also significant differences among different varieties. The order of drought resistance of 3 hybrid soybeans was obtained by comprehensive analysis of membership function value method, Hybrid soybean-A-5> Hybrid soybean No.6>Jindou 48.【Conclusion】 The photosynthesis inhibition, osmotic adjustment and antioxidant enzyme activities could respond to drought stress of 3 hybrid soybeans. The Hybrid soybean-A-5 can be used as a demonstration of drought resistant hybrid soybean to promotion and demonstration in Huanghuaihai Area. It also provides an important reference for drought resistant breeding of hybrid soybean in later stage. [ABSTRACT FROM AUTHOR]

The paper is dealing with the effects of the late drought stress on the productivity and yield components of 12 varieties and 7 lines of winter bread wheat, which differ in morphophysiological characteristics. It was found that drought stress created in the late period decreased productivity, number of spikes per sheaf, number of spikelets per spike, number and mass of grains per spike and mass of 1000 grains by 19.9%, 7.7%, 4.9%, 12.8%, 21,6%, and 10.01%, respectively. As can be seen, of the components directly affected by water stress, the productivity and grain mass per spike were the most depressed, while number of spikes per unit area and number of spikelets per spike was relatively stable. Under late drought stress, Gobustan and Gyrmyzy gul 1 varieties, 7thWON-SA No.465 and Ferrigineum 2/19 lines manifested the highest productivity (557, 515, 607, and 549 g/m², respectively). Under drought stress, the most depressed values for 1000-grain mass were found for the genotypes Tale 38, Gyrmyzy gul 1, 12thIWWYT No.8, and Ferrigineum 2/19, while the least depressed values were found for Sonmez 01, Gobustan, 4thFEFWSN No.50 and 7thWON-SA No.477. [ABSTRACT FROM AUTHOR]

Purpose: Seed orientation is widely known to affect shoot growth, but the effects on root growth and crop drought tolerance are unclear. Thus, one germination paper experiment, two soil pot experiments and one field experiment were conducted to study the effects of seed orientation (Brush-up, Brush-down, Crease-up and Crease-down) on crop root and shoot growth under two water treatment levels (full and deficit) using winter wheat (Triticum aestivum L.) as an example. Methods: Seedling root traits, early shoot growth, mature root distribution, soil water consumption, root/shoot ratio, harvest index and grain yield were measured. Results: The results showed that under full irrigation, the control Brush-up orientation allowed for the highest grain production, mainly due to shoot growth. However, Crease-down resulted in the highest yield under limited-water supplies because root biomass was optimally related to grain yield in the pots, and a reasonably deep root system (lower root biomass and longer specific root length) benefitted yield production in the field. The higher shoot biomass, lower root/shoot ratio and higher harvest index also contributed to a higher grain yield under deficit irrigation, suggesting that sowing seeds lying flat with the crease down can optimize root and shoot growth and improve drought tolerance. Conclusions: To our knowledge, this is the first report verifying that seed orientation can significantly regulate root growth under dry conditions, providing a possible new mechanism underlying crop drought tolerance. [ABSTRACT FROM AUTHOR]

Forest tree species are likely to be affected by drought due to global climate change. Drought and nitrogen (N) affect plant growth. Therefore, we should understand the mechanisms underlying the N availability and species response to drought for plant development. This paper had two objectives. First, it determined the effects of N addition on water potential, gas exchange parameters, soluble sugar and photosynthetic pigment content, leaf N concentration, and growth parameters under drought stress and well-watered conditions. Second, it searched the drought response of Quercus ithaburensis Decne. subsp. macrolepis (Kotschy) Hedge & Yaltırık seedlings under N conditions with drought stress. In a greenhouse, one-year-old seedlings were exposed to two drought stress and nitrogen addition and three drought cycles. Drought stress significantly reduced stem water potential, relative water content, net photosynthetic rate, stomatal conductance, transpiration rate, leaf area, root collar diameter, seedling height, shoot and root dry weight. On the other hand, it increased water use efficiency and soluble sugar content. N addition is effective on soluble sugar content and photosynthetic pigment content, and promoted leaf N concentrations. Nitrogen addition under well-watered conditions stimulated the growth of Q. ithaburensis seedlings. Drought stress changed the physiological response of Q. ithaburensis seedlings (decreased water potential, net photosynthetic rate, stomatal conductance, and transpiration rate) in the short term, although nitrogen addition under drought stress has not changed the decreasing trend overall. [ABSTRACT FROM AUTHOR]

As one of the three alpine flowers in the world and one of the ten traditional famous flowers in China, Rhododendron has high ornamental value and broad landscape applications. However, most of them are naturally distributed in high-altitude mountains, and they prefer cool and humid climate for the restriction of genetic mechanism. Drought is the key factor to restrict their ex-situ conservation and landscape application. As Rhododendron have many different species, cultivars and ecological types, distributed in a wide area, the mechanisms of different species or cultivars responses to drought stress are different. In this paper, how Rhododendron responses to drought stress and the effects of exogenous substances on improving the drought resistance of Rhododendron in China and abroad were reviewed from the aspects of seed germination, morphological and anatomical characteristics, physiological and biochemical parameters, gene expression, etc. In addition, the deficiency of current research and the future research directions were also discussed. It is proposed that the water use strategy and drought resistance mechanism of different ecological types and different drought resistances of Rhododendron should be future studied, as well as the gene regulation mechanism of mycorrhizal fungi for improving the drought resistance and the screening of excellent strains. This study provides the basis for the diversity conservation, the exploitation of drought resistance resources and the landscape applications of Rhododendron in China. [ABSTRACT FROM AUTHOR]

Background: Use of soil amendments in agriculture is an old practice and with increase in demand of organic agriculture, it is gaining more attention. Work on the quality of the produce more particularly if crop faces any adverse situation like drought are scarce. This paper provides a comparative assessment of organic (farm yard manure) and inorganic (biochar) soil amendments on grain quality of grass pea (Lathyrus sativus L.) when crop faces drought. Different grain quality parameters were studied along with crop health and grain yield under the application of soil amendments during drought. Results: Biochar and farm yard manure (FYM) lowered drought‐induced leaf water potential (upto 22%) and root nitrate reductase activity (by 62% and 67% respectively). Both inorganic and organic soil amendments improved in vitro protein digestibility (up to 16% and 37% respectively). Whereas higher grain phytic acid content (increased up to 40%) was noted from application of organic amendment (FYM) compared to inorganic (16% increase in biochar treated plots). Protein yield is enhanced (8%) under the application of Biochar‐enhanced protein yield by 8% when crops experienced drought at vegetative stage, whereas FYM reduced it by 9% under the same situation. Conclusion: Tested soil amendments can improve grain quality of grass pea. However, they were not equally efficient when the crop experienced drought at either stage of growth. Thus, screening of soil amendment is important when added under stressful situation like drought to ascertain better grain quality for consumers. [ABSTRACT FROM AUTHOR]

Plants confront several environmental stresses that are crucial in defining plant productivity. Among these environmental stresses, drought stress is recognized as the foremost abiotic factor which affects the food security around the globe due to its negative impact on the plant development, and quality of plant products. Because of this, drought stress has gained an imperative appearance in the field of plant sciences in recent years. Silicon (Si), an agronomically essential mineral nutrient, is recognized highly advantageous in enhancing plant growth at various phases of plant life cycle under water deficit circumstances. Si has been considered extensively useful in mitigating harmful consequences of drought stress by enhancing root H 2 O absorption, regulating uptake of nutrients, reducing transpiration rate, improving photosynthetic activity, increment in the production of compatible solutes and by elevating plant antioxidant defense functioning. Si also known to improve plant endurance to limited water availability by inducing the functioning of various stress associated genes. To maximize the potential benefits and sustainable efficiency of Si in agriculture, it is of crucial importance to gain knowledge about the underlying mechanisms of how Si counteract stress conditions. Various findings suggested that Si increases the plant's immune system against drought stress, and application of Si is an important approach to shield plants from adverse stress conditions and soil nutrient depletion. This paper shows that Si has imperative and noteworthy impacts on improving plant tolerance to drought stress via maintaining cellular homeostasis. Present review mainly provides an insight into silicon role as beneficial element to alleviate drought stress in plants by regulating their morphological, physicochemical and molecular characteristics. • Silicon (Si) is an agronomically essential mineral nutrient. • Si is highly advantageous in enhancing plant growth and productivity under drought stress conditions. • Si application improve plant tolerance to drought stress by triggering the expression of various stress associated genes. [ABSTRACT FROM AUTHOR]

【Objective】The present paper aimed to identify the augophagy(ATG) gene of Vicia faba L. based on the results of transcriptional sequencing, and analyze its response to drought stress, which provides theoretical reference for further study on the mechanism of these genes under drought stress.【Method】According to the annotation of Swiss port, NCBI,ensemble and other databases, the ATG gene of V. faba L. was screened and identified based on RNA sewuencing data. The conserved domain, subcellular localization prediction, phylogenetic tree and motif were analyzed by SMART,MEGA-X and MEME software. Based on transcriptome data, the expression differences of ATG gene in V. faba L. varieties CDAS105(drought tolerant) and ECAN No.1(sensitive) were analyzed under drought stress.【Result】 Twelve ATG genes from V.faba L. were screened and annotated, all of which contained autophagy domain. According to the different C-terminal domains, they were divided into five subfamilies: ATG3,ATG6,ATG8,ATG18 and ATG26. In the phylogenetic tree constructed by faba bean ATG gene and Arabidopsis,maize, rice and yeast, it was found that genes with the same C-terminal domain were clustered together. Prediction of subcellular localization indicated the elevent genes and one ATG gene were located in extracellular and cytoplasm, respectively. Gene structure analysis showed that there were no introns in the DNA sequences of ATG family genes in V. faba L.,and they were composed of UTR and CDs regions. Conserved motif analysis identified that these proteins contained 20 mortifs. Analysis of ATG expression showed that ATG18 b,ATG18 c and ATG8 a were up-regulated in drought resistant varieties after 16 hours or 64 hours drought treatment, and the expression of ATG8 a in drought resistant varieties was further enhanced with the increase of drought treatment time. 【Conclusion】Twelve ATG genes were identified and distributed in five subfamilies. ATG8 a, ATG18 b and ATG18 c responded to drought stress, which could be used as potential gene resources to improve the drought tolerance during seed germinating in faba bean. [ABSTRACT FROM AUTHOR]

Sunflower seeds (hybrid Luka) were primed with water (hydropriming) or sodium hydrosulphide (NaHS) solutions (0.1, 0.5, 1.0 and 1.5 mM NaHS) and subsequently dried to initial moisture content. Unprimed (control) and primed seeds were germinated in a growth chamber on paper towels moistened with water or polyethylene glycol (PEG) 6000 solutions (2.5, 5.0 and 10%), mimicking different drought stress levels. To evaluate the response of the primed seeds to drought in the germination stage, the germination energy (GE), germination rate (SG), seedling fresh mass (SW), hydrogen peroxide and free proline content (PRO), as well as lipid peroxidation rate (malondialdehyde; MDA) were established. The results show strong effects of the imposed drought stress and the metabolic response to oxidative stress through lower germinability and proline accumulation in seedlings. NaHS priming showed some positive effects on seed germination depending on stress level and the concentration of NaHS. Sunflower seeds were also germinated in pots filled with soil, at optimal (70% of field water capacity [FWC 70%]) and drought conditions (FWC 30%), in natural outdoors conditions. When plantlets developed the first pair of leaves, the number of plants (emergence rate [ER]), shoot mass (SM) and leaves mass (LM) were determined, as well as the total activities of catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) and dehydroascorbate reductase (DHAR). There was a significant influence of an interaction between drought stress and priming, whereas drought stress inhibited plant emergence and early growth (SW and LW), and strong antioxidative enzymatic response to drought stress was clearly established in the leaves. Although seed priming showed some influence on enzyme activities, it was mostly related to seed hydropriming effects, while NaHS seed priming was less effective, influencing only DHAR. Altogether, the results imply that sunflower seed priming with NaHS may not have a prolonged impact on the antioxidative defence mechanism based on CAT and ascorbate/glutathione cycle during sunflower early growth in drought conditions. [ABSTRACT FROM AUTHOR]

Water absorption is one of the major factors limiting rice seeds germination rate. It is very important to study the drought-tolerance mechanism of rice under drought stress, in order to improve the drought-tolerance capacity of rice and thereby increase the yield. In this paper, 2 varieties of rice seeds were placed in 10%, 20% PEG (polyethylene glycol) 6000 solution and control solution respectively, and moisture variation was analyzed with T2 relaxation spectrum and proton density weighted image of low field nuclear magnetic resonance (NMR) 0, 6, 22, 48, and 72 h later after seed germination. The influence of PEG solution on water absorption was studied, and the regression equation was deduced between relative moisture content and total signal amplitude of nuclear magnetic signal in this paper. The proton density weighted images obtained by the magnetic resonance imaging system can show the absorption and flow patterns of water during the germination of rice seeds directly. The germination test results showed that the drought resistance of H9710 is higher than that of LX1. The proton density weighted image results showed that water molecules enter the seed directly through cracks on the seed surface, and embryo absorbs water molecules and expands downwards firstly. After 24 h, the nutrient in the seeds flows to the seeds embryo to provide adequate nutrition for the growth of the radicle and germ. The seeds absorbed less water and the germination process was inhibited obviously under PEG stress, and the higher the PEG mass fraction, the less the water absorption and the slower the germination process. This is consistent with the results of T2 relaxation spectrum detection. Based on the theory of NMR and multicomponent characteristics of T2 relaxation spectrum, when inversion frequency was 10000 times, the water in rice seeds during germination was categorized into 2 phases, which were short relaxation time standing for bound water and long relaxation time standing for free water. The T2 relaxation spectrum results suggested that the amplitude of NMR signals of the bound water, that of the free water and the total amplitude all increased gradually. The drought tolerance of rice seeds is closely related to the relative water absorption rate after 24 h, and PEG solution inhibits the absorption of water; the higher the PEG mass fraction, the stronger the inhibition. The relative water absorption rate of rice varieties with stronger drought resistance was higher than that with weaker drought resistance. The change of NMR signals directly reflects the moisture distribution and water absorption of rice seeds during germination. In addition, the moisture content of the seeds and the total amplitude of NMR signals were positively correlated(R2=0.983). This indicated that the data obtained by NMR technique were consistent with those obtained by the conventional dry-weight weighing method. Therefore it is a proper method to detect the moisture content in seeds during germination with NMR technique. By this regression equation, the moisture content of each state of water during seed germination can be calculated. These empirical data offer a reference for the study of rice seeds’ response mechanism under drought stress during seed germination and the screening of germplasm resources, and also develop a new nondestructive detecting technology of moisture for plants under stress. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to study the effects of drought stress on fruit quality, sugar acid content and related enzyme activity in the process of development, and to provide a theoretical basis for drought resistance and disaster reduction of Huangguogan. [Method] In this experiment, seven years old Huangguoganfruit trees were used as the experimental materials. Field experiment with strict design to control the water laminating to mimick different degrees of drought stress was conducted. Related indexes of fruit quality were analyzed. [Result] Drought stress can inhibit the fruit size of Huangguogan. Light drought stress can effectively improve the content of soluble solids, total soluble sugar and the ratio of sugar to acid,and light drought stress can enhance the activity of SS (sucrose synthetase) synthesis direction in the fruit at the later stage of fruit development, which is conducive to the accumulation of soluble sugar in the fruit. Cytoplasmic ACO (aconitase) and NAD-IDH (isocitrate dehydrogenase) are the key enzymes for the difference of organic acid content in the late stage of fruit development. Drought stress enhanced the degradation of organic acids in fruits by increasing the activity of these two enzymes. [Conclusion] The effects of drought stress on sugar increasing and acid decreasing of Huangguoganfruits mainly occurred at the later stage of fruit development, and light drought stress can improve the comprehensive quality of citrus fruits. [ABSTRACT FROM AUTHOR]

[Objective] The aim of this paper was to explore the function of LEA3 gene and the molecular mechanism of drought resistance of Festuca Arundinacea, for which LEA3 gene from two Guizhou native F. Arundinacea cultivars ( Qiancao 1 and Qiancao 2) were cloned and the bioinformatics of LEA3 genes and their expression under drought stress at seedling stage were analyzed as well. [Method] In this experiment, we cloned LEA3 genes of Qiancao 1 and Qiancao 2 by RT-PCR, referring to the sequences recorded by NCBI. At the same time, the amino acid sequence was analyzed by relevant software, and the expression of amino acid under drought stress was analyzed by real-time fluorescence quantitative PCR ( qRT-PCR). [ Result ] In this study, we found that LEA3 genes in Qiancao 1 and Qiancao 2 consisted of open reading frame (ORF) of 609 bp and 642 bp respectively, which encoded proteins of 203 and 213 amino acids residues, respectively. Compared with Qiancao 2, the LEA3 protein of Qiancao 1 lacks the motif composed of 11 amino acids. At the same time, 11 amino acid differences were found between Qiancao 1 and Qiancao 2. Bioinformatics analysis showed that the molecular weight of Qiancao 1 LEA3 protein was 20. 72 kDa, the isoelectric point was 8. 55, and the grand average of hydropathicity ( GRAVY) was - 0. 971. The LEA3 protein of Qiancao 2 has a molecular weight of 22. 01 kDa, an isoelectric point of 8. 99, and a GRAVY of - L 069. The hydrophobicity analysis showed that both Qiancao 1 and Qiancao 2 LEA3 proteins had no transmembrane structure, and the hydrophilicity of Qiancao 2 LEA3 was stronger than that of Qiancao 1 LEA3. Alpha-helixes are dominant in Qiancao 1 and Qiancao 2 LEA3 proteins. LEA3 proteins of Qiancao 1 and Qiancao 2 have high homology with that of barley, goatgrass, wheatgrass and wheat. The phylogenetic tree showed that LEA3 proteins of Qiancao 1, Qiancao 2, wheat, ryegrass, barley, goatgrass, bromus inermis and wheatgrass were clustered into one group. The results of qRT-PCR analysis showed that the expression of Qiancao 1 LEAJ was higher than that of Qiancao 2 in the whole process of drought stress at seedling stage. Compared with mild stress, the response of LEA3 in Qiancao 1 and Qiancao 2 under severe stress was stronger. [ Conclusion] It was found that the drought resistance of Qiancao 1 and Qiancao 2 was positively correlated with the expression of I.EAJ gene. Under the same conditions of drought stress, the expression of Qiancao 1 LEAJ gene was higher than that of Qiancao 2. Therefore, it can be inferred that Qiancao 1 is more adaptable to arid environment than Qiancao 2. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to investigate the effects of wood vinegar on growth and physiology of flue-cured tobacco under drought stress, and provide a theoretical basis for in-depth application of wood vinegar in flue-cured tobacco cultivation. [Method] Yunyan 87 was used as research object to analyze the effects of peanut shell vinegar, fruit wood vinegar and peach shell vinegar on agronomic traits, SP AD value, malondialdehyde (MDA), proline (Pro) content, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activities of flue-cured tobacco under drought stress. [Result] Under normal watering and drought stress, the growth and SPAD value of fluecured tobacco applied with different wood vinegar were higher than that of the control, and peach shell vinegar performed better, the maximum SPAD values were 46. 6 and 44. 33 under normal watering and drought stress, respectively. The MDA contents were 3. 98-4. 31 and 4. 53-6. 12 f.LmoV g,respectively under normal watering and drought stress, and Pro contents were 123. 45-13. 427 and 183. 28-237. 97 f.Lg/ g, respectively. The contents of MDA and Pro of flue-cured tobacco under drought stress applied with different wood vinegar was higher than normal watering. The activities of SOD, POD and CAT in different treatments were all greater than those in normal watering, the average increasing rate was 24. 05 %, 47.36 % and 17. 30 %, respectively. [Conclusion]Wood vinegar could promote the growth of tobacco plants and improve the drought resistance of flue-cured tobacco. The peach shell vinegar solution performed better. [ABSTRACT FROM AUTHOR]

Isoprene concentrations were measured at four heights below, within, and above the forest canopy in Wytham Woods (United Kingdom) throughout the summer of 2018 using custom‐built gas chromatographs (the iDirac). These observations were complemented with selected ancillary variables, including air temperature, photosynthetically active radiation, occasional leaf gas exchange measurements, and satellite retrievals of normalized difference vegetation and water indices. The campaign overlapped with a long and uninterrupted heatwave accompanied by moderate drought. Peak isoprene concentrations during the heatwave‐drought were up to a factor of 4 higher than those before or after. Higher temperatures during the heatwave could not account for all the observed isoprene; the enhanced abundances correlated with drought stress. Leaf‐level emissions confirmed this and also included compounds associated with ecosystem stress. This work highlights that a more in‐depth understanding of the effects of drought stress is required to better characterize isoprene emissions. Plain Language Summary: Plants emit a number of volatile organic compounds into the atmosphere as a response to environmental stimuli such as temperature and incoming sunlight. Once emitted, these compounds undergo chemical processes that can affect local air quality (for instance, contributing to the formation of pollutants such as ground‐level ozone) and climate (by contributing to the formation of aerosol particles). Numerical models have been developed to successfully simulate volatile emissions under most environmental conditions. However, one notable exception is during extreme weather events such as heatwaves and droughts, where current models appear inadequate. In this paper, we present a unique data set consisting of continuous measurements of isoprene, the main volatile emission from vegetation, during the summer of 2018 in a UK temperate forest. A prolonged heatwave and drought affected the United Kingdom that summer. We report unusually high levels of isoprene and show that higher temperatures during the heatwave cannot account for all the observed isoprene. Our analysis shows that ecosystem stress brought about by moderate drought correlates with the enhanced isoprene. This work enables an improved description of isoprene emissions under extreme events (droughts) that are predicted to become more frequent in the near future as a consequence of global change. Key Points: Isoprene concentrations were monitored for a whole growing season in a temperate forest in the United Kingdom before, during, and after the 2018 heatwaveIsoprene abundances during the heatwave increased by up to 400%, and stress‐related sesquiterpenes were observed during the heatwaveHigher temperatures in the heatwave cannot account for all the enhanced isoprene abundances, which correlate to drought stress [ABSTRACT FROM AUTHOR]

【Objective】The present paper aimed to explore the effect of nitrogen application of Nitraria tangutorum seedlings under drought stress.【Method】This experiment simulated drought stress, sprayed different concentrations of nitrogen fertilizer on Nitraria tangutorum seedlings(0, 6, 36, 60 mmol·L-1), studied root morphological characteristics and endogenous hormones.【Result】（i）Nitrogen addition could promote root elongation and elongation of Nitraria tangutorum under drought stress, when the nitrogen concentration reached 36 mmol·L-1, the fine and small roots increased to the maximum; for medium roots, when the nitrogen concentration reached 60 mmol·L-1, the promotion effect was the best.（ii）Nitrogen addition could increase root surface area, volume and number of root tips of Nitraria tangutorum under drought stress. After nitrogen application, the maximum values of surface area, volume and number of root tips of Nitraria tangutorum were 155.74 cm2, 2.67 cm3 and 2370.00 respectively, 46.80 cm2, 1.03 cm3 and 408.67 more than those without nitrogen application.（iii）Under drought stress, nitrogen addition could promote the synthesis of IAA, ABA and GA3. Analysis of variance showed that nitrogen had no significant effect on IAA（P>0.05）; nitrogen promoted ABA and GA3 significantly（P<0.05）.（iv）The correlation analysis of root morphological indexes and endogenous hormones of Nitraria tangutorum showed that the correlation among these indexes was not strong, and only individual indexes showed significant correlation. 【Conclusion】In a word, nitrogen addition could improve the drought resistance of Nitraria tangutorum from root and endogenous hormones, but not the higher the concentration of nitrogen, the better the growth of Nitraria tangutorum. [ABSTRACT FROM AUTHOR]

Major abiotic stress factors such as salt and drought adversely affect important physiological processes and biochemical mechanisms and cause severe loss in crop productivity worldwide. Plants develop various strategies to stand healthy against these stress factors. The accumulation of proline (Pro) is one of the striking metabolic responses of plants to salt and drought stress. Pro biosynthesis and signalling contribute to the redox balance of cell under normal and stressful conditions. However, literature is meager on the sustainable strategies potentially fit for modulating Pro biosynthesis and production in stressed plants. Considering the recent literature, this paper in its first part overviews Pro biosynthesis and transport in plants and also briefly highlights the significance of Pro in plant responses to salt and drought stress. Secondly, this paper discusses mechanisms underlying the regulation of Pro metabolism in salt and drought-exposed plant via phytohormones, mineral nutrients and transgenic approaches. The outcome of the studies may give new opportunities in modulating Pro metabolism for improving plant tolerance to salt and drought stress and benefit sustainable agriculture. [ABSTRACT FROM AUTHOR]

[Objective]The aim of this paper was to screen Paspahim dilatalum germplasms with strong drought resistance, and provide theoretical basis for the breeding and promotion of drought resistant germplasm. [Method] A drought simulation pot experiment was carried out with six P. dilatalum germplasms, and then the changes of various physiological indexes under drought stress were evaluated by means of principal component analysis and membership function. [Result] Under drought stress, the malondialdehyde contents of all the six germplasms gradually increased from the start to the 21st day, then a sharp increase was observed during 21st -28th days. The peroxidase activity, catalase activity,and soluble protein content increased first and then decreased,reached the maximum at 14 day,with one exception that the soluble protein in P. dilatalum germplasm coming from Meitan, Guizhou reached the maximum at 7th d. The total soluble sugar content displayed a significant upward trend,while the chlorophyll content showed a significant downward trend. The results of principal component a-nalysis showed that the cumulative contribution rate of the first three principal components reached 92.64 % ,which could be identified as a comprehensive index for drought resistance evaluation. Comprehensive evaluation of drought resistance showed that the drought resistance of the P. diliilatum germplasm from USA was the strongest,followed by the one from Anlong (grass slope) , Guizhou, the one from Vietnam was relatively weak, and the other germplasms rank in the medium position. [ Conclusion ] In the breeding and promotion of drought-resistant P. dilaUitum germplasms, American P. ddalatum germplasms with stalwart drought resistance should be selected priorly. [ABSTRACT FROM AUTHOR]

Water stress disrupts horticultural crop growth, development and finally results in low productivity particularly in arid and semi arid parts of the world. Plants require certain physical, chemical and biological factors for their growth and development. Any deviation from these factors may cause aberrant metabolic changes and plant experience a tension known as stress. Water stresses trigger a wide variety of plant responses, ranging from altered gene expression and cellular metabolism to changes in plant growth, leaf morphology and movement and root development and finally productivity. Drought stress modifies photosynthetic rate, relative water content, leaf water potential, and stomatal conductance. Finally, it destabilizes membrane structure and permeability, protein structure and function, leading to cell death. Drought tolerant plants possess various mechanisms like reduction in water loss by reducing stomatal conductance or morphological modification, improving water uptake by developing efficient root systems and accumulation of osmolytes. Management practices employed for drought stress management in horticultural crops include use of drought tolerant crop varieties, use of tolerant root stocks, canopy management, wind breaks, regulated deficit irrigation and partial root zone drying, uses of anti-transpirants etc. The varieties selected should have deep root system (bael, ber), leaf shedding (ber, lasoda, pomegranate), thorns on stem (ker, karonda, ber), stomata at lower side (custard apple), wax coating (ber), thin foliage and leaf orientation (aonla), hair on leaf and sunken stomata (fig, phalsa, ber and lasoda). This paper elaborates physiological, biochemical and molecular mechanism of drought tolerance along with drought stress management in horticultural crops. [ABSTRACT FROM AUTHOR]

Histone modification is an important epigenetic mechanism in eukaryotes. Histone acetyltransferase and deacetylase regulate histone acetylation levels antagonistically, leading to dynamic control of chromatin structure. One of the histone deacetylases, HDA6, is involved in gene silencing in the heterochromatin regions, chromocenter formation, and metabolic adaptation under drought stress. Although HDA6 plays an important role in chromatin control and response to drought stress, its intracellular localization has not been observed in detail. In this paper, we generated transformants expressing HDA6-GFP in the model plant, Arabidopsis thaliana, and the crops, rice, and cassava. We observed the localization of the fusion protein and showed that HDA6-GFP was expressed in the whole root and localized at the nucleus in Arabidopsis, rice, and cassava. Remarkably, HDA6-GFP clearly formed speckles that were actively colocalized with chromocenters in Arabidopsis root meristem. In contrast, such speckles were unlikely to be formed in rice or cassava. Because AtHDA6 directly binds to the acetate synthesis genes, which function in drought tolerance, we performed live imaging analyses to examine the cellular dynamics of pH in roots and the subnuclear dynamics of AtHDA6 responding to acetic acid treatment. The number of HDA6 speckles increased during drought stress, suggesting a role in contributing to drought stress tolerance. [ABSTRACT FROM AUTHOR]

This paper investigates historical growth and climate records among the oak sites representing the northern edge of species range in northernmost Europe (Finland). This is to characterize plant-climate interactions for a multitude of sites where oak decline has recently been observed and understand this most recent decline in the context of the past decline studies elsewhere. Further, our paper demonstrates the procedures the tree-ring data can be used in isolating those factors significantly contributing to decline. Our findings point towards complex tree mortality dynamics. Compared to oaks that remain healthy, the declining and dead oaks represent the trees clearly having suffered from competition and edaphic position within their site. This was indicated by their reduced growth rates and more drastic growth disturbance, with indications of reduced resilience. Growth of these trees was also deteriorated by cold soil temperatures during the dormancy in addition to summer droughts. By contrast, the growth of healthy oaks has been notably ameliorated by springtime soil warming over the past decades. The results demonstrate the climatic determinants for observed decline in the northern oak sites, which may become increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought, although their habitats are not normally considered water-limited. [ABSTRACT FROM AUTHOR]

Little is known about how soil properties control tree growth at its upper limit. This paper reviews the state of knowledge and discusses the results specifically related to ecozones, to the scale-dependent importance of single factors, and to new findings from a near-natural treeline ecotone in Rolwaling Himal, Nepal. This paper identifies gaps in literature and shows where new research is needed, both conceptual and geographical. The review shows that at a global scale and throughout diverse ecozones, growing season soil temperature is considered a key factor for tree growth. Soil temperatures differ greatly at a local scale, and are mainly determined by local climatic, edaphic, and topographic conditions. Our result of 7.6 ± 0.6°C for growing season mean soil temperature at treeline in Rolwaling is 1.2 K higher compared to the postulated 6.4 ± 0.7°C for alpine treelines. We suggest a broadening of the ±0.7°C error term to cover the wide range at a local scale. The role of major soil nutrients and soil moisture for treeline shift has been underestimated by far. In Rolwaling, significantly decreasing nutrient availability (N, K, Mg) in soils and foliage with elevation might explain why treeline shift and global warming are decoupled. Further, soil moisture deficits early in the year impede seedling and sapling establishment, which could be an important mechanism that controls treeline position. These findings question previous results which argue that alpine treelines are unaffected by soil nutrient availability and soil moisture. We assume that specific combinations of soil properties as well as single soil properties limit tree growth even below climatic treelines. [ABSTRACT FROM AUTHOR]

Betulin and oleanolic acid are pentacyclic triterpene compounds with a broad range of biological and medicinal properties. Herein, we demonstrated that 2-year-old white birch saplings were capable of synthesizing betulin and oleanolic acid, and the accumulation of these compounds was significantly affected by seasonal and environmental factors. Indeed, the triterpenes accumulated mainly in the stem bark, with little in the root bark and leaves. From May to October, betulin and oleanolic acid stem bark accumulation displayed an inverted 'V' curve, peaking in late July to late August (warmest summer months in Haerbin, China). Interestingly, low nitrogen levels promoted root bark and leaf accumulation of oleanolic acid, while high nitrogen amounts were more favorable to oleanolic acid and betulin accumulation in the stem bark. Moderate and mild drought during the accumulation peak period promoted oleanolic acid and betulin accumulation in the stem bark. Serious shortage of soil moisture inhibited the accumulation of both triterpenes. From July to August, high nitrogen (N3) treatment increased lupeol synthase (BPW) and beta-amyrin synthase (BPY) gene expression in the stem bark. Water stress, especially mild and moderate, induced BPW and BPY expression and downregulated cycloartenol synthase (BPX) in the stem bark. This study provides a strong basis for understanding triterpenoid synthesis in birch at the molecular level. [ABSTRACT FROM AUTHOR]

【Objective】 The presented paper explored the effect of drought stress on the growth of oat seedlings. 【Method】Qingyan No. 1 was chosen to cultivate through a hydroponic experiment, and the six concentrations of polyethylene glycol(PEG-6000) including(0, 5, 10, 15, 20, 25 %) and three times(0, 7, 14 days) were used to simulate different drought conditions. Under the six different concentrations, the indexes including chlorophyll, relative water content, relative conductivity and vegetation of growth state were measured. 【Result】The chlorophyll content and relative water content were on the decline since drought stress. When the PEG concentration was 5 % the chlorophyll at 7 thday, the content and relative water content in leaves had the significant difference(P < 0. 05) with control; When the concentration of PEG was 15 %, the chlorophyll a and chlorophyll b, total chlorophyll content and relative water content compared with control decreased53. 98 %, 40. 57 %, 50. 26 % and 64. 61 %, respectively on the last day under drought stress; The relative conductivity was increasing with the increase of PEG concentration and stress time, but at 7 thday, the relative conductivity had no significant difference with different PEG concentrations(5 %, 10 %, 15 %); Under various drought stress, oat seedlings fresh weight significantly decreased, but under light drought stress, the root dry weight induced by 5 % or 10 % PEG significantly increased, there was no significant difference by 15 PEG, but the root dry weight significantly decreased by 20 or 25 PEG. 【Conclusion】To sum up, PEG concentration could cause the growth inhibition of oat seedlings. When PEG concentration was below 15 %, it could be simulated as a drought test for oats seedlings and moderate stress and improve the drought resistance of oat seedlings. [ABSTRACT FROM AUTHOR]

[Objective]The present paper aimed to study the effect of drought stress on the garden trees in arid area of southern Xinjiang to provide a basis for drought resistance selection of garden trees. [Method]Taken five species of Populus alba, Fraxinus rhynchophylla, Quer-cus robur, Xanthoceras sorbifolium and Jugiqns nigra as tested materials, the pot experiments were conducted, the comparisons of five tree species of protective enzymes and osmotic adjustment substances in the trend under drought conditions were made. [Result]The soluble protein content and protective enzyme activities of the five tree species increased with the drought stress duration, of which the activity of the Populus alba tree was the most significant, and the activity of the activity of the Xanthoceras sorbifolium tree was smaller. Their MDA contents and proline contents increased with the duration of drought stress, and the content of proline was significantly changed. [Conclusion] Through membership function comprehensive evaluation and analysis, the drought tolerance of 5 tree species from high to low were : Xanthoceras sorbifolium > Populus alba - Fraxinus rhynchophylla > Jugiqns nigra > Quercus robur. [ABSTRACT FROM AUTHOR]

Water deficit is one of the main factors to limit sugar cane production. This paper's goal is to characterize biometrically varieties of sugarcane under different water regimes. The experiment was performed using randomized design with three repetitions in parcels subdivided in time, in which three varieties: RB855156, RB835486 e RB867515 (plots), with absence and presence of irrigation (irrigated and rainfed - subplots) to which the plants were subjected, and data collection in six observations in time (50, 100, 150, 200, 250 and 300 days after cutting - DAC), were the subsubplots. The following biometrics were assessed: mean stem diameter (MSD), mean tiller height (MTH), number of green and completely open leaves (NoFOGL), length and width of +3 leaf (C+3 and L+3, respectively), leaf area index (LAI), leaf area (LA) and productivity. The data were subjected to variance analysis and regression at p<0.05. The variety RB867515 was the one that displayed higher MSD, MTH, C+3 and L+3 biometric values, both in irrigated cultivation and rainfed; it was observed that there was a decrease in NoFOGL values per tiller when the varieties were grown in rainfed conditions; the RB867515 variety had higher productivity, not differentiating to the RB855156, and proved better suited to water stress during the beginning of cultivation cycle. [ABSTRACT FROM AUTHOR]

To date, few attempts have been made to assess the influence of climate change on forest ecosystems and on the relationship between tree growth and climate in humid areas of low latitudes. In this paper, we studied the response of tree growth and forest ecosystem to climate change by using Fokienia hodginsii tree-ring cores from the northern Yunnan-Guizhou Plateau, southwest of China. Tree growth correlates the highest ( r = −0.64, p < 0.01) with mean temperature (July-September), but the coefficients were changing with time as revealed by a moving correlation analysis. Tree growth is significantly ( p < 0.05) and positively correlated with January-April mean temperature from AD 1961-1987, while correlations with precipitation are insignificant. In contrast, from 1988 to 2014, tree growth correlated negatively with mean temperature of previous summer and positively with precipitation of previous August-September. This indicated that the limiting factors for tree growth have changed under different climate conditions. The meteorological data suggested that from 1961 to 1987 it was cold and wet in the study area and radial growth is limited by winter and spring temperatures. This restriction is weaker if the climate is appropriate in general. However, from 1988 to 2014, the combined effects of recent warming and decreasing precipitation have led to an increasing response of tree-ring width to drought. In addition, a large proportion of mature F. hodginsii mortality occurred from 2007 to 2013, which corresponds with a drastic reduction of radial growth (narrowest in recent 100 years). The recent drought, induced by decreasing precipitation and increasing temperature, may have passed the threshold which F. hodginsii could tolerate, causing tree growth reduction, tree growth-climate relationship change, as well as catastrophic tree mortality. All these changes may lead to further responses of the local ecosystem to climate change which should be highly regarded. [ABSTRACT FROM AUTHOR]

Background and aims: In many plant species, hydrogen sulfide (HS) triggers stomatal closure, which is produced mainly by two classes of enzymes, cysteine desulfhydrases (CDes) and O-acetyl-L-serine (thiol) lyases (OASTLs). Stomatal movement is accompanied by several ion fluxes across the plasma membranes of guard cells. Methods: In this paper, we detected the fluxes of H, Ca, K and Cl in guard cells of wild-type Arabidopsis thaliana and the mutants associated with HS production ( lcd, OE-LCD, des, OE-DES, oastl-a1, oastl-a2, oastl-b and oastl-c), using a non-invasive micro-test technique. Results: The results showed that endogenous HS induced a transmembrane K efflux, and Ca and Cl influxes, while not affecting the flow of H. Furthermore, the K channel was the main osmolyte responder during the regulation of stomatal movement by HS in response to drought stress. Finally, the two classes of enzymes produced HS, CDes and OASTLs, played different roles in regulating stomatal movements. Conclusions: Thus, HS mediates ion fluxes inducing stomatal closure in response to drought stress in Arabidopsis thaliana. [ABSTRACT FROM AUTHOR]