Water Stress Conditions Research Articles

A hybrid multifunctional physicochemical sensor suite for continuous monitoring of crop health

This work reports a first-of-its-kind hybrid wearable physicochemical sensor suite that we call PlantFit for simultaneous measurement of two key phytohormones, salicylic acid, and ethylene, along with vapor pressure deficit and radial growth of stem in live plants. The sensors are developed using a low-cost and roll-to-roll screen printing technology. A single integrated flexible patch that contains temperature, humidity, salicylic acid, and ethylene sensors, is installed on the leaves of live plants. The strain sensor with in-built pressure correction capability is wrapped around the plant stem to provide pressure-compensated stem diameter measurements. The sensors provide real-time information on plant health under different amounts of water stress conditions. The sensor suite is installed on bell pepper plants for 40 days and measurements of salicylic acid, ethylene, temperature, humidity, and stem diameter are recorded daily. In addition, sensors are installed on different parts of the same plant to investigate the spatiotemporal dynamics of water transport and phytohormone responses. Subsequent correlation and principal component analyses demonstrate the strong association between hormone levels, vapor pressure deficit, and water transport in the plant. Our findings suggest that the mass deployment of PlantFit in agricultural settings will aid growers in detecting water stress/deficiency early and in implementing early intervention measures to reduce stress-induced yield decline.

Water requirement of Urban Green Infrastructure under climate change

The increased uncertainty of rainfall and high urban temperatures resulting from climate change present challenges for water management in Urban Green Infrastructure (UGI). UGI is an important component of cities, and it plays a crucial role in addressing various environmental issues (e.g., floods, pollutants, heat islands, etc.). Effective water management of UGI is essential to ensure its environmental and ecological benefits in the face of climate change. However, previous studies have not adequately investigated water management strategies for UGI under climate change scenarios. This study aims to estimate the current and future water requirement and effective rainfall (rainwater stored in the soil and plant roots available for plant evapotranspiration) to determine the irrigation requirement of UGI during periods of rainfall deficit under current and future climate conditions.The results indicate that the water requirement for UGI will continue to increase under both RCP4.5 and RCP8.5 climate scenarios, with a larger increase projected under RCP8.5. For instance, the average annual water requirement for UGI in Seoul, South Korea is currently 731.29 mm, and it is projected to increase to 756.45 mm (RCP4.5) and 816.47 mm (RCP8.5) during the period of 2081–2100, assuming low managed water stress condition. In addition, the water requirement of UGI in Seoul is the highest in June (approximately 125–137 mm) and the lowest in December or January (about 5–7 mm). While irrigation is unnecessary in July and August due to sufficient rainfall, other months in Seoul require irrigation when rainfall is insufficient. For example, continuous insufficient rainfall from May to June 2100 and April to June 2081 would need >110 mm (RCP4.5) of irrigation requirement even under high managed water stress condition. The findings of this study provide a theoretical foundation for water management strategies in current and future UGI settings.

Mycorrhizal inoculation under water stress conditions and its influence on the benefit of host microbe symbiosis of Terminalia arjuna species

BackgroundEntisol is a very poor, compact, and low-water-holding capacity soil. They are obstacles to the plant's root system's penetration and the availability of water, particularly in dry months. However, Arbuscular mycorrhizae fungi (AMF) is used for seedling growth and reduces water stress in the plant.ResultsIn this experiment, the growth parameters and the physiological activities of the plant were changed for the well watering (WW), fractionated watering (FW), and stopped/no watering conditions of the T. arjunaseedling. This experiment demonstrated higher mycorrhizal dependency (24.90%) under the FW condition than that of the WW condition (18.58%). Also the root colonization was higher (67%) under FW plants compared to WW plants (53%) associated with AMF+ in T. arjuna seedling. Photosynthesis was found 24.27% more with FW than the WW condition. Experiment' shows posivitivecorrelation between the photosynthesis and interval of no watering for AMF− plants (r2 = 0.873 for AMF− (control) and comparatively very weak for plants with AMF+ (r2 = 0.259 for AMF+ plants).ConclusionsThe findings confirms the use of AMF in entisol soil to improve plant growth and biomass by reducing edaphic stress.

Assessment of Genetic Correlation, Path Coefficient Analysis and Principal Component Analysis in Horse Gram under Water Stress

A field experiment was conducted to evaluate the correlation and path analysis in thirty horse gram germplasm lines under moisture-stressed conditions using various selected characters. The association studies revealed a significant positive correlation of seed yield with relative water content, number of pods per plant, number of seeds per pod, total chlorophyll content, harvest index, proline content, root dry weight, root length and leaf area index. While days to 50% flowering, days to maturity, plant height and number of primary branches showed a significant negative correlation with yield. Path coefficient analysis revealed a high positive direct effect of the number of pods per plant on seed yield and the number of seeds per pod recorded exhibited the highest indirect effect on seed yield via the number of pods per plant under moisture stress conditions in horse gram. So, selection based on the number of pods per plant will be more beneficial under water stress conditions. The exploitation of genetic diversity is key to a successful breeding program. The principal component analysis using selected fifteen characters revealed the existence of adequate genetic variability among genotypes under study. First four principal components accounted for a cumulative variance of 82.47%. The principal component analysis (PCA) biplot revealed genotypes viz. IC22785, IC392329, HG 26L and IC20753 to highly diverse and these genotypes may be employed for enhancement of various traits in horse gram.

Soil water migration under three tree species in response to water stress and extreme rainstorms

In arid and semi-arid areas, plant growth and survival are directly related to the soil water content. The soil water content is an important parameter for monitoring land degradation. A better understanding of how forests use soil water is crucial for the quantification how the terrestrial hydrologic cycle adapts to forestry practices and regional climate anomalies in these areas. This study investigated the variation of the water balance under different precipitation patterns (including soil water redistribution patterns under water stress and extreme rainstorms) under three common tree species in a mountainous area of Beijing were investigated. The results showed that soil water storage in the 80–150 cm layer played an important role for the ability of Platycladus orientalis (L.) Franco and Quercus variabilis Blume to survive drought during a dry season. Compared to P. orientalis and Q. variabilis, the duration of water stress was shortest for Pinus tabulaeformis Carr. (15 months). P. tabulaeformis had a higher ability to utilize top soil water but showed a less balanced use of soil water in each soil layer. It also had the strongest ability to replenish groundwater through deep seepage. P. tabulaeformis may resist drought by transferring water to deeper soil horizons, where it is less susceptible to evaporation and where moisture can be temporarily stored. P. orientalis and Q. variabilis are more dependent on soil water storage in response to water stress conditions.

Silicon amendment – influence on sorghum growth, yield, and nutrient uptake under water stress

Silicon enhances plant growth and development, alleviating the effects of biotic and abiotic stresses. Drought severe abiotic stress that hampers plant growth and production globally, posing threat to food security. Mass production of sorghum is crucial to eradicating the present increasing food insecurity in water-stressed regions. The study evaluated the effects of silicon on nutrients uptake, growth and yield of sorghum under different water regimes. A two-season field trial was carried out to evaluate two sorghum varieties (seredo and Machakos local red), silicon (with silicon and without silicon) under three irrigation regimes (20%, 40% and 60%) laid out in Randomized Completely Block Design in a factorial arrangement replicated thrice. Data was collected on growth, yield and nutrients uptake, which was subjected to analysis of variance using R software. Results showed that Seredo variety had the highest root dry weight (123.5 g) and longest roots (51.4 cm). At 60% water regime and silicon amendment enhanced sorghum growth better than other treatments. Seredo variety recorded the highest grain yield (4.82tha−1), phosphorus (95.53 kg ha−1), nitrogen (32.16 kg ha−1), K (76.06 kg ha−1), calcium (3919.00 kg ha−1) and magnesium (165.02 kg ha−1). Seredo had the maximum harvest index of 0.41. At 40% water regime, Seredo variety amendment with Si produced the highest grain yields and nutrients uptake. Si amendment can improve sorghum growth and yield under water stress conditions, as indicated by high grain yield and nutrients uptake achieved at 40% water regime. The use of Silicon is recommended for improving sorghum productivity in regions experiencing low rainfall.

Detection of susceptible Norway spruce to bark beetle attack using PlanetScope multispectral imagery

Climate change-related acute or long-term drought stress can weaken forest ecosystems and result in widespread bark beetle infestations. Eurasian spruce bark beetle (Ips typographus L.) infestations have been occurring in Norway spruce [Picea abies (L.) Karst.]-dominated forests in central Europe including the Czechia. These infestations appear regularly, especially in homogeneous spruce stands, and the impact varies with the climate-induced water stress conditions. The removal of infected trees before the beetles leave the bark is an important step in forest pest management. Early identification of susceptible trees to infestations is also very important but quite challenging since stressed tree-tops show no sign of discolouration in the visible spectrum. We investigated if individual spectral bandwidths or developed spectral vegetation indices (SVIs), can be used to differentiate non-attacked trees, assumed to be healthy, from trees susceptible to attacks in the later stages of a growing season. And, how the temporal-scale patterns of individual bands and developed SVIs of susceptible trees to attacks, driven by changes in spectral characteristics of trees, behave differently than those patterns observed for healthy trees. The multispectral imagery from the PlanetScope satellite coupled with field data were used to statistically test the competency of the individual band and/or developed SVIs to differentiate two designated classes of healthy and susceptible trees. We found significant differences between SVIs of the susceptible and healthy spruce forests using the Enhanced Vegetation Index (EVI) and Visible Atmospherically Resistant Index (VARI). The accuracy for both indices ranged from 0.7 to 0.78; the highest among all examined indices. The results indicated that the spectral differences between the healthy and susceptible trees were present at the beginning of the growing season before the attacks. The existing spectral differences, likely caused by water-stress stimuli such as droughts, may be a key to detecting forests susceptible to early infestations. Our introduced methodology can also be applied in future research, using new generations of the PlanetScope imagery, to assess forests susceptibility to bark beetle infestations early in the growing season.

WATER STRESS INDUCED CHANGES IN PHYSIOLOGICAL ATTRIBUTES OF MUNGBEAN

The production of mungbean [Vigna radiata (L.)] is adversely affected by drought in the tropics and sub-tropics. This study investigated the physiological responses of six mungbean varieties viz. BUmug 2, BUmug 4, BARI Mung-5, BARI Mung-6, Binamoog-5 and Binamoog-8 to non-stress (80% of field capacity) and water deficit (50% of field capacity) conditions. The experiment was laid out in a completely randomized design having four replications at the research field of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur. The variety Binamoog-5 showed the highest level of physiological parameters related to drought tolerance, such as proline content (32.57%), xylem exudation (577.00 mg hr-1 and 383.70 mg hr-1) and total chlorophyll content (2.65 mg g-1 and 2.81 mg g-1) at preflowering and pod development stage, photosynthesis (38.94 μmol m-2 s-1 CO2 ), transpiration (15.00 mg H2 O/dm2 /h), and relative water content (66.14%), whereas that showed the lowest level of cell membrane thermostability (63.8%) under water stressed condition, followed by Binamoog-8. The measured physiological characteristics of other varieties were affected noticeably. Therefore, Binamoog-5 may be considered as a resource for drought tolerant genetic material.

Effect of Different Bacillus Species on Morphological Parameters, Chlorophyll Content and Relative Water Content of Rice under Water Stress Condition

Multiple factors are threatening food security through climate change. Potential effect of this is seen in the variability of rainfall received with drought as the most critical factor that is affecting the growth and yield of plants. Plant growth promoting bacteria (PGPB) are taunted as one of the most promising organisms to counter the drastic effect of climate change especially in drought condition. They facilitate the growth of plants and helps alleviate the stresses brought by abiotic stress conditions. Three previously isolated Bacillus species labeled (SA1 (Bacillus subtilis), SA3 (Bacillus niacini) and SB1 (Bacillus cereus)) were tested for plants growth promoting enhancement in rice under water stress condition. Growth parameters; Root length, shoot length, fresh of root and dry weight of root were all tested using standard techniques. Chlorophyll content was measured using SPAD chlorophyll meter while relative water content of the leaves was calculated using a standard formula. Among all the three Bacillus species tested, Bacillus subtilis (SA1) was found to enhance all the measured growth parameters, relative water content and chlorophyll content in the rice under water stress condition to a significant extent when compared with other Bacillus species. Therefore, Bacillus subtilis (OM184294) could be a potential candidate as PGPB especially under drought conditions.

Genetic analyses of stay green for tolerance to water stress and nitrogen deficiency in Algerian Saharan maize populations

Delayed senescence could contribute to maintain yield under water stress and low nitrogen stress. Landraces from arid areas can provide favorable alleles for stay green under stress. The objectives of this study were to estimate varietal and heterosis effects of Algerian Saharan populations and their crosses for stay-green under water stress and no-nitrogen fertilization and to identify the most promising populations as sources of stay-green under stress. Six Algerian maize populations were evaluated in a diallel under water stress (300 mm irrigation) versus control (600 mm) and no-nitrogen fertilization versus 120 kg/ha N fertilization. Both varietal and specific heterosis were involved in delayed senescence under stress. Breeding programs could capitalize additive components by using the populations IZM or IGS with favorable varietal effects for delayed senescence under nitrogen stress, or dominance effects by using the population AOR with favorable heterotic effects for plant color under water and nitrogen stresses. Based on specific heterosis, under water stress conditions with no-nitrogen supply, the most promising cross was AOR × IZM for delayed senescence, while IZM × BAH (with no-nitrogen supply), and SHH × BAH (with nitrogen fertilizer), will allow a longer maintenance of the plant coloration. We suggest reciprocal recurrent selection with these populations for developing drought-tolerant and low nitrogen hybrids to improve stay-green.

Analysis of the Differentially Expressed Proteins and Metabolic Pathways of Honeybush (Cyclopia subternata) in Response to Water Deficit Stress.

Honeybush (Cyclopia spp.) is a rich source of antioxidant properties and phenolic compounds. Water availability plays a crucial role in plant metabolic processes, and it contributes to overall quality. Thus, this study aimed to investigate changes in molecular functions, cellular components, and biological processes of Cyclopia subternata exposed to different water stress conditions, which include well-watered (as Control, T1), semi-water stressed (T2), and water-deprived (T3) potted plants. Samples were also collected from a well-watered commercial farm first cultivated in 2013 (T13) and then cultivated in 2017 (T17) and 2019 (T19). Differentially expressed proteins extracted from C. subternata leaves were identified using LC-MS/MS spectrometry. A total of 11 differentially expressed proteins (DEPs) were identified using Fisher's exact test (p < 0.00100). Only α-glucan phosphorylase was found to be statistically common between T17 and T19 (p < 0.00100). Notably, α-glucan phosphorylase was upregulated in the older vegetation (T17) and downregulated in T19 by 1.41-fold. This result suggests that α-glucan phosphorylase was needed in T17 to support the metabolic pathway. In T19, five DEPs were upregulated, while the other six were downregulated. Based on gene ontology, the DEPs in the stressed plant were associated with cellular and metabolic processes, response to stimulus, binding, catalytic activity, and cellular anatomical entity. Differentially expressed proteins were clustered based on the Kyoto Encyclopedia of Genes and Genomes (KEGG), and sequences were linked to metabolic pathways via enzyme code and KEGG ortholog. Most proteins were involved in photosynthesis, phenylpropanoid biosynthesis, thiamine, and purine metabolism. This study revealed the presence of trans-cinnamate 4-monooxygenase, an intermediate for the biosynthesis of a large number of substances, such as phenylpropanoids and flavonoids.

Regeneration and Rejuvenation of Water Bodies in the City of Bhawanipatna

Abstract: Water is one of the essential resources for human survival.it is also a precious national resource linked to every aspect of development. With less than 3% of the Earth's water being fresh, the need to conserve and manage it is crucial. Global warming, climate change causes inadequate rainfall which are the reason for the water stress condition of india.it effect the level of water in ponds and lakes and eventually dries them up. Water bodies like lakes and ponds are integral for drinking water, agriculture, and urban purposes. Assessing freshwater resources and implementing conservation measures are essential for sustainable development. Watershed development, rainwater harvesting, and water recycling are essential for sustainable water supply in the coming future. Regeneration and rejuvenation of water bodies are important for sustainable development of cities and town as they help in water conservation, ground water recharge, improve climatic conditions, supports bio-diversity, etc. In which community plays important role in the regeneration and rejuvenation process. Bhawanipatna is the city and the districts headquarter of the Kalahandi district in the Indian state of Odisha. These water bodies both big and small have an inseparable impact on the aestheticity and operational functionality of the city. They are a vital part of the temperature regulatory mechanism and help the city in various other ways. Bhawanipatna, having highest population growth in the Kalahandi District, faces an imminent and acute water scarcity due to the lack of development as compared to other cities. Asha Sagar Pond which is located at the epicenter of Bhawanipatna has a significant amount of land cover that impacts the lifestyle and influences the microclimate of the study area. Implementation of water management scheme with local community participation is essential for sustainable urban development of cities and towns. Restoration methods such as preventive and ameliorative method can help in overcoming water scarcity at a micro to city level. There is a growing concern in many quarters that the world is running out of water. According to the United Nations Development Programme (UNDP) Human Development Report 2006, for over a billion people around the world, water access is unreliable, unsafe or beyond their purchasing power (UNDP, 2006). Urban areas in India are facing a water crisis due to loss of watershed, increasing levels of pollution, deteriorating water balance, lowering of water table and a dire lack of groundwater recharge (Singh, 2012). Regeneration and rejuvenation of water bodies are important for sustainable development of cities and town as they help in water conservation, ground water recharge, improve climatic conditions, supports bio-diversity

FTIR spectroscopy-based lipochemical fingerprints involved in pomegranate response to water stress

Pomegranate trees are known for their ability to withstand drought conditions, but there is still much to learn about how water stress affects the lipobiochemical behavior of their seeds. This study aimed to investigate how sustained deficit irrigation (SDI-50), equivalent to 50% of crop evapotranspiration, influences pomegranate seed oil attributes such as phenols, flavonoids, and tannins content, and the seeds’ lipochemical fingerprints compared to fully irrigated trees. At the full ripening stage, pomegranate seeds were analyzed for their oil content, biochemical traits, and vibrational fingerprints using infrared radiation. The results indicated that there was a significant genotypic effect coupled with applied water stress on all the investigated traits. Interestingly, an increasing trend in seed oil yield was observed under water stress conditions compared to the control, with the highest oil yield increase observed in the ‘Zheri Precoce’ fruit seeds. Only two cultivars did not show the same pattern, with the oil yield increase ranging from 8% to 100%. Furthermore, SDI-50 induced a substantial increase in total phenolic content, coupled with a significant genotypic effect, and resulted in an average increase of 7.5%. This increase in total phenolics also correlated with an increase in antioxidant activity across all investigated cultivars. ATR-FTIR fingerprinting revealed eleven spectral fingerprints corresponding to functional groups present in pomegranate seeds oil, with a particular pattern of significant effects of both genotypic and SDI-50 factors. These results suggest that exploiting water scarcity conditions could be a viable approach to improve the quantitative and qualitative attributes of pomegranate seed oil. While there are still several aspects to be investigated further, this study provides a basis for pomegranate processing under water shortage conditions.

Developing an environmental friendly approach for enhancing water retention with the amendment of water-absorbing polymer and fertilizers

The effect of climate/environmental change has resulted in adverse water stress conditions which necessitates the sustainable approaches for improving the water use efficiency to boost agricultural production in Central Asia. Water-absorbing polymer (WAP) has emerged as one of the amendments for soil water stress management. WAP are chemically cross-linked structure capable of absorbing and storing a large amount of water. The agricultural land has different levels of fertilizers which can influence the performance of WAP because of its sensitivity due to external ionic medium. Therefore, the combined or hybrid use of WAP and organic/ inorganic fertilizers may inhibit the functionality of WAP, which needs to be thoroughly investigated. This study demonstrates the performance of two different WAPs (a commercially WAP (crosslinked potassium polyacrylate) and a laboratory synthesized WAP (crosslinked fly ash-polyacrylate superabsorbent composite)) with varying combinations of fertilizers in silt loam (agrarian soil). The combined use of fertilizers and WAP have improved the water retention properties of soils due to modification in the soil pore volume for both the WAPs. Quantification from water retention properties revealed a significant increase in plant wilting time (PWT) and plant available water content (PAWC) under the combined influence of fertilizers and WAP amended soils, indicating the possibility of high-water availability to plant roots. The study suggests the potential of WAPs as an efficient soil conditioner even in the presence of fertilizer for countering the negative impacts of water stress conditions. WAPs might minimize the requirement for chemical fertilizers, which helps to enhance the climate/environmental change and agriculture sector in the Central Asian region.

Thermal infrared reflectance characteristics of natural leaves in 8–14 μm region: Mechanistic modeling and relationships with leaf water content

The use of thermal infrared (TIR) remote sensing, between 8 and 14 μm, is an important method to monitor vegetation water stress status. To comprehend the spectral characteristics of natural leaves, understanding the relationship between TIR reflectance and leaf water content is helpful. In this study, we selected Magnolia cylindrica E.H.Wilson, Canna indica Rosc. and Gardenia jasminoides J. Ellis leaves to isolate cuticles with varying thicknesses. Subsequently, we constructed a leaf thermal infrared model (Leaf-TIR model) to examine the impact of cuticle thickness and inside wet epidermal cell wall on the TIR reflectance of natural leaves. Our findings indicate that the cuticle thicknesses of the three selected leaves are 12.2, 5.5, and 1.1 μm, respectively. Moreover, as cuticle thickness decreases, the similarity between the isolated cuticle and the leaf reflectance behaviors also decreases because a thinner cuticle has lower absorptance and a weaker effect on the reflection characteristics of natural leaves. Moreover, we observed that as the water content in the cell wall decreases, the reflectance of the leaves significantly increases when the cuticle thickness becomes 5.5 or 1.1 μm. This outcome is due to the increasing difference in the refractive indices of the cuticle and cell wall with declining water content. Our findings suggest that the Leaf-TIR model can quantitatively determine the relationship between TIR reflectance and water content in the cell wall. This information is crucial in interpreting TIR spectral behaviors of natural leaves and provides an important theoretical basis for future research.

Evaluation of Vegetative Development of Quinoa under Water Stress by Applying Different Organic Amendments

Prolonged drought periods, increasingly occurring worldwide due to global climate change, could affect the growth and productivity of both traditional and climate-resilient crops, including quinoa. Specifically, the vegetative growing cycle of this species is highly sensitive to drought conditions. In this context, using organic amendments could help plants cope with drought due to their ability to enhance soil water status. So, the current study aimed to investigate the effect of different organic amendments, i.e., two biochars (from woodchips and vineyard prunings) and a vermicompost (from cattle manure), applied to the soil alone and mixed at 2% rate (w/w), on the vegetative development of quinoa (cv. Titicaca), during which a period of water stress was imposed from the twelve-leaf stage to the bud stage. A set of growth-related parameters were measured both during and at the end of the experiment, along with a set of water-related parameters, at the end of the water-stress period and after soil re-watering. The results showed that woodchip biochar, both alone and mixed with vermicompost, significantly affected plant growth during the water-stress period, also allowing a quicker recovery once drought conditions ended. Indeed, the leaf number and area, SPAD index, leaf and stem fresh weight, and dry matter content in plants treated with woodchip biochar, alone and mixed with vermicompost, were higher than vineyard pruning biochar, alone and mixed with vermicompost and similar to the well-watered control plants. Similar results were observed considering the yield contributing traits detected at the end of the experiment, including the main panicle length, number of sub-panicle, as well as fresh weight and dry matter content of both panicle and sub-panicles. Additionally, the water-related parameters, especially the low turgid weight to dry weight ratio of woodchip biochar treated plants, showed evidence of better growth than vineyard pruning biochar. At the end of the experiment, the WUE of plants treated with woodchip biochar and vermicompost, both alone and mixed, was higher than vineyard pruning biochar alone and mixed with vermicompost. Among the tested organic amendments, woodchip biochar alone and mixed with vermicompost positively affected the vegetative growth response of quinoa under water-stress conditions.

The drought-tolerant rhizobacterium, Pseudomonas putida AKMP7, suppresses polyamine accumulation under well-watered conditions and diverts putrescine into GABA under water-stress, in Oryza sativa

Drought-tolerant plant growth promoting rhizobacteria (PGPR) have been reported to alleviate water-stress in plants that they associate with. Here, we report the impact of a free-living, drought-tolerant PGPR strain, Pseudomonas putida AKMP7 on (a) morpho-physiological responses and (b) metabolism of the three major polyamines-namely, putrescine (Put), spermidine (Spd) and spermine (Spm) in well-watered and water-stressed Oryza sativa (BPT5204). The bacterium significantly improved the plant growth and biomass, decreased membrane damage, electrolyte leakage and plant proline levels under water-stress, indicating drought alleviation. Dehydration did not affect the root colonization efficiency of the bacterium. We observed that the concentrations of all three polyamines were downregulated in rice leaves under well-watered conditions by AKMP7 inoculation. Under water-stress, however, AKMP7 caused a significant decrease only in the levels of foliar Spm, while Put and Spd levels did not majorly fluctuate. Transcript levels of most of the polyamine biosynthetic genes studied (AIH involved in Put biosynthesis; SPD/SPM2, SPD/SPM3 and SAMDC2, involved in Spd and Spm biosynthesis) positively correlated with the low polyamine levels in the inoculated plants, vs. the non-inoculated ones under well-watered conditions. While similar trends were observed in the water-stressed, inoculated plants vs. water-stressed, non-inoculated plants, the reduction in only Spm (and not Put and Spd) was a potential consequence of the interplay of both, its biosynthesis and back-conversion. In water-stressed plants, AKMP7 caused a small downregulation in AIH, while stronger downregulations in the expressions of SPD/SPM2 as well as SAMDC2 were seen. Furthermore, the Spd to Put back-conversion gene, PAO3 exhibited a downregulation on AKMP7 treatment under water-stressed conditions. There was also an increase in the expression of BADH2 gene, leading to a concomitant increase in foliar GABA levels in inoculated, water-stressed plants vs. their non-inoculated counterparts. The overall conclusion from this study is- P. putida AKMP7 tightly regulates polyamine homeostasis in rice plants, both under well-watered and water-stressed conditions by lowering polyamine levels, through (a) transcriptional control of polyamine biosynthetic genes under well-watered conditions and (b) a combination of biosynthesis, back-conversion and catabolism of polyamines under water-stress.

Assessing the effect of climate and land use changes on the hydrologic regimes in the upstream of Tajan river basin using SWAT model

Climate change is the most important challenge in achieving sustainable development. Semi-arid and arid areas (such as Iran) are particularly susceptible to the effects of climate change on water supply. In this research, the effect of climate change and upstream land use is investigated on Tajan, a river in the north of Iran. The data regarding the climate were produced via second-generation Canadian Earth System Model (CanESM2) and adopted as the input to SWAT hydrologic model under RCP2.6 and RCP8.5 for the period of 2016–2066. The results showed that the peak streamflow will increase by 4% and 5.7% and the average annual discharges will decrease by 16% and 16.5% from 2016 to 2066 for RCP2.6 and RCP8.5 scenarios, respectively. Besides, the effect of different land use change scenarios on streamflow was investigated under four diverse scenarios selected to represent a comprehensive range of possible land use map of the basin. Land use change scenarios led to 8.5–15.8% increase in the average annual streamflow, highlighting the fact that it is less effective than climate change on streamflow. It could be concluded that downstream water users in the basin should adopt strategies to cope with water-stressed condition under the changing climate.

Deciphering the mechanisms of microbe mediated drought stress alleviation in wheat

Drought stress adversely influences the crop plants. Herein, present research was designed to elucidate the role of plant growth promoting bacteria for amelioration of water stress in wheat. A pot experiment was conducted for screening the microorganisms on the basis of plant growth, chlorophyll and proline content under water stress. Bacillus sp. BT3 and Klebsiella sp. HA9 were found to be more promising strains that positively influenced the plant growth, chlorophyll and proline status of seedlings under water stress condition. Further, Bacillus sp.BT3 and Klebsiella sp. HA9 along with check strain (BioNPK) were used for elucidating their detailed effect on morphological, biochemical, physiological and molecular traits to mitigate water stress in wheat. Microbial inoculation significantly improved plant height, fresh weight and dry weight of root and shoot, relative water content, chlorophyll content and root morphological parameters over the uninoculated water stressed (30% FC) control. Likewise, sugar content, protein content and antioxidant enzymes were also significantly enhanced due to microbial inoculation under water stress (30% FC). Microbial inoculation significantly decreased proline, glycine betaine, lipid peroxidation, peroxide and superoxide radicals in wheat over the uninoculated water stressed (30%FC) control. Quantitative real-time (qRT) PCR analysis revealed that Bacillus sp. BT3, Klebsiella sp. HA9 and BioNPK inoculation significantly upregulated stress responsive genes (DHN, DREB, L15 and TaABA-8OH) over the uninoculated water stressed (30% F.C.) control. The study reports the potential of Bacillus sp. BT3 and Klebsiella sp. HA9 along with BioNPK in water stress alleviation in wheat which could be recommended as effective bioinoculants.

Hydric Behavior: Insights into Primary Metabolites in Leaves and Roots of Cabernet Sauvignon and Grenache Grapevine Varieties under Drought Stress

The classification of grapevine cultivars into isohydric and anisohydric categories depends on their ability to close stomata under conditions of low soil water availability or high atmospheric demand. This study aimed to compare the responses of Grenache, classified as isohydric, and Cabernet Sauvignon, classified as anisohydric, both grafted onto Richter 110 rootstock, and subjected to severe drought stress. Three cycles of drought stress were applied, followed by watering, while a well-watered treatment served as the control. Stomatal conductance and stem water potential were measured at predawn and midday during the drought cycles, and primary metabolites were analyzed in leaves and roots using gas chromatography. We found that Grenache had significantly higher stomatal conductance than Cabernet Sauvignon under both well-watered and water-stressed conditions. There were no significant differences in stem water potential between the two varieties, but the control treatment maintained a higher stem water potential at predawn and midday for both varieties. Primary metabolite analysis showed that both varieties accumulated sugars and polyols in their leaves and roots under drought stress, while organic acids were more abundant in leaves than in roots. Overall, the results suggest that the hydric behavior of grapevines depends on the intensity and duration of drought stress. In this study, both varieties exhibited near-isohydric behavior by regulating stomatal closure under drought stress. The metabolites identified in this study may serve as potential biomarkers of water drought stress in Grenache and Cabernet Sauvignon grapevines under the conditions of this experiment.