Mild Water Stress Research Articles

Evaluation of Genotypes against Water Stress and Salinity in Rice (Oryza sativa L.)

Abiotic stresses pose significant challenges to growth, yield and productivity thus threatening food security. Hence, it is essential to develop climate resilient rice varieties that mitigate the impact of abiotic stress. A study on physiological characterization for water and salinity stress was conducted in twenty-eight rice genotypes during kharif 2023 at Regional Agricultural Research Station, Maruteru. Among all the treatments, root length, shoot length, root and shoot dry weight and chlorophyll content was maximum under control followed by 1% mannitol, 2% mannitol and salinity stress. Visual scoring for water stress at seedling stage revealed that under mild water stress (1% M) more than 90% of plants survived in genotypes viz., AC-35678, FL 478, Ravana, Rahaspunjar, AUS 63, AUS 73, Vandana, NICRA 16, NICRA 17, CR-3439-4-E-17-2-1-B-1-S-1, CR-4215-2-5-2-M-4-SUB-2-5-1. Under severe water stress (2% M) more than 70% of the seedlings survived in NICRA 16, CR-4215-2-5-2-M-4-SUB-2-5-1, CRAC-4423-3, IET -18727, IC-516 149, IET-18716, AC-35678, FL 478, AC 85, Rahaspunjar, AUS 100, NICRA 17, CR-3439-4-E-17-2-1-B-1-S-1. Under salinity stress the score 3 was recorded in FL 478, and 5 in Rahaspunjar, IET -18727, NICRA 16, Ravana, NICRA 17. For both combined stresses, FL 478, Rahaspunjar, NICRA 16 and NICRA 17 were identified as tolerant and can be identified as donors for development of rice varieties having climate resilience.

Cross‐Generational Effect of Water Deficit Priming on Physiology of Peanut Plants Under Water Stress

ABSTRACTWater deficit priming through regulated deficit irrigation has been shown to be beneficial for peanut cultivation, leading to improved water‐use efficiency during the crop cycle and enhanced stress acclimation. The effects of priming using water deficit can be heritable, but little is known about stress priming effects on the physiology and growth of successive generations undergoing water stress. Two experiments were conducted to assess cross‐generational priming by determining physiological and growth responses of offspring of primed and non‐primed peanut plants of two genotypes, COC‐041 and New Mexico Valencia C (NMV‐C), both previously found to be strongly responsive to priming. Seeds were collected from parental plants subjected to mild water stress by regulated deficit irrigation (primed) or adequate irrigation (non‐primed). These seeds were then planted, and the offspring were monitored for physiological and growth responses to water stress, including on a whole‐plant basis using a high‐throughput physiological phenotyping platform and on individual leaves by periodic single‐leaf measurements. Measurements included whole‐plant transpiration (plant‐Tr), root water uptake, leaf transpiration, stomatal conductance and net CO2 assimilation (leaf‐Tr, leaf‐gs, and leaf‐A), leaf water and osmotic potential (leaf‐Ψw and leaf‐Ψo), leaf osmotic adjustment, leaf relative water content (leaf‐RWC) and cumulative plant‐Tr. Offspring of both genotypes from primed parent plants had faster early establishment, with more uniform germination, and more rapid initial seedling growth compared to offspring from non‐primed parent plants. Although offspring of both non‐primed and primed plants of both genotypes exhibited a significant reduction of plant‐Tr, gas exchange, leaf‐Ψw, leaf‐Ψo, and leaf‐RWC when exposed to water stress, offspring of primed plants showed increased water use efficiency through reduced leaf‐gs, leaf‐Tr and plant‐Tr while maintaining leaf‐A under water stress. Despite offspring of both primed and non‐primed plants being susceptible to severe water stress, offspring of primed plants exhibited overall enhanced water use efficiency, leading to greater dry biomass production per gram of transpired water and a trend of less growth reduction due to water stress compared to offspring of non‐primed plants, especially for the genotype COC‐041. This study shows the potential of water deficit priming to promote cross‐generational changes in physiological function under limited water availability, by enhancing crop stress acclimation in the next plant generation.

Hydrus-1D Model for Simulating Potassium Transport in Rice Crop Irrigated with Alternate Wetting and Drying Practice

ABSTRACT Potassium (K) is one of the essential nutrients that play a crucial role in rice fields; however, its availability, transport, and balance components can be influenced by alternating wetting and drying (AWD) irrigation practice. This study used the Hydrus-1D solute transport model to simulate K transport and balance components in AWD irrigated rice fields. Thirty lysimeter field experiment plots with three different irrigation treatments (No: no soil water stress, MS: mild soil water stress (400 cm), and SS: severe soil water stress (750 cm)) were used for rice cultivation. Daily measurements of soil matric potential head (SMPH) and ponding water depth (PWD) were recorded. Throughout the rice-growing season, leachate water samples from the surface (ponding water) and soil profiles were collected to measure K content. Using the lysimeter field experiment data, the Hydrus-1D model simulated K transport in the AWD rice field. The simulation results indicate that the K distribution predominantly occurred within the top puddled soil layer (0–20 cm) in AWD practice. This suggests that the recommended K fertilizer dose with a 4–5 cm PWD and SMPH of 400 cm optimizes K availability for rice while limiting K leaching loss. The Hydrus-1D model proves to be a valuable management tool, aiding in determining optimal K application rates and ponding water depths for AWD irrigation, ensuring sufficient K nutrients for rice, and controlling K loss for sustainable rice production.

Effects of water and exogenous glucose on apple seedling growth and soil enzyme activity in semiarid area.

Soil water and organic carbon (C) are key factors affecting the growth and development of apple seedlings. The objective of the study was to investigate the effects of different soil moisture and glucose supplies on apple seedling growth and soil enzyme activities. We hypothesized that the growth of apple seedlings was affected by soil water and C content through their effects on root structure, plant physiological properties and soil enzymatic activities. A pot experiment consisting of nine treatments was set up, including three water treatments with soil moisture contents at 75-85% (normal irrigation, CK), 65-75% (light water stress, LS), and 55-65% (mild water stress, MS) of the soil field capacity, in combination with three glucose treatments with carbon/nitrogen (C/N) ratio of 7.5 (C1, no adding glucose), 10 (C2) and 15 (C3), respectively. Results showed that the LSC2 treatment significantly increased plant height by 7%, stem diameter by 5% and leaf area by 17%, as compared with LSC1. Also, LSC2 significantly increased root dry weight, root vitality and soil enzyme activities. Moreover, results of leaf photosynthetic, malondialdehyde (MDA), peroxidase (POD), superoxide dismutase (SOD) and proline contents also proved that adding glucose improved the drought resistance of plants. LSC2 treatment is more conducive to the growth of apple seedlings, and application of carbon has a good alleviation effect on plant water stress. The study demonstrated that addition of exogenous glucose alleviated light water deficiency, significantly affected root vitality, and promoted apple seedling growth. © 2024 Society of Chemical Industry.

Film mulching counteracts the adverse effects of mild moisture deficiency, and improves the quality and yield of Cyperus esculentus. L grass and tuber in the oasis area of Tarim Basin.

Plastic film mulching (PFM) and deficit irrigation (DI) are vital water-saving approaches in arid agriculture. Cyperus esculentus is a significant crop in dry zones. However, scant data exists on the impacts of these water-saving methods on C. esculentus yield and quality. Using randomized block experiment design. Three irrigation strategies were tested: CK (standard irrigation), RW20 (20% water reduction), and RW40 (40% water reduction). Mulchin treatments included film mulching (FM) and no film mulching (NFM). Results revealed substantial effects of film mulching and drip irrigation on soil nutrients and physical properties, with minor influence on grass, root, and tuber stoichiometry. PF treatment, DI treatments, and their interaction significantly affected C. esculentus forage and tuber yields. Initially, grass and tuber yields increased and then decreased with reduced irrigation. The highest yields were under RW20 (3716.31 and 4758.19 kg/ha). FM increased grass and tuber yield by 17.99% and 8.46%, respectively, over NFM. The water reduction augmented the biomass distribuiton of the leaf and root, while reducing the tuber biomass in NFM. FM significantely impacted grass ether extract content, while reduced water influenced grass and tuber crude protein and tuber ether extract content. Mild water stress increased ether extract, crude protein, and soluble matter in grass and tubers, while excessive RW decreased them. Integrating soil traits, nutrients, yield, and quality, findings indicate C.esculentus yield and quality primarily hinge on soil water content, pond hydrogenase, and electrical conductivity. Based on this results, the recommended strategy is to reduce irrigation by 20% for cultivating C. esculentus in this area.

Effects of water stress on nutrients and enzyme activity in rhizosphere soils of greenhouse grape.

In grape cultivation, incorrect water regulation will lead to significant water wastage, which in turn will change soil structure and disrupt soil nutrient cycling processes. This study aimed to investigate the effects of different water regulation treatments [by setting moderate water stress (W1), mild water stress (W2), and adequate water availability (CK)] on soil physical-chemical properties and enzyme activity in greenhouse grape during the growing season. The result showed that the W2 treatment had a negative impact on the build-up of dissolved organic carbon (DOC), nitrate nitrogen (NO3-N), and available phosphorus (AP). Throughout the reproductive period, the W1 and W2 treatments decreased the soil's microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) contents, and MBC was more vulnerable to water stress. During the growth period, the trends of urease, catalase, and sucrase activities in different soil depth were ranked as 10-20 cm > 0-10 cm > 20-40 cm. The urease activity in 0-10 cm soil was suppressed by both W1 and W2 treatments, while the invertase activity in various soil layers under W1 treatment differed substantially. The W1 treatment also reduced the catalase activity in the 20-40 cm soil layer in the grape growth season. These findings suggested that W2 treatment can conserve water and enhance microbial ecology of greenhouse grape soils. Therefore, W2 treatment was the most effective water regulation measure for local greenhouse grape cultivation.

Impact of predicted climate change environmental conditions on the growth of Fusarium asiaticum strains and mycotoxins production on a wheat-based matrix

Fusarium asiaticum is a predominant fungal pathogen causing Fusarium Head Blight (FHB) in wheat and barley in China and is associated with approximately £201 million in annual losses due to grains contaminated with mycotoxins. F. asiaticum produces deoxynivalenol and zearalenone whose maximum limits in cereals and cereals-derived products have been established in different countries including the EU. Few studies are available on the ecophysiological behaviour of this fungal pathogen, but nothing is known about the impact of projected climate change scenarios on its growth and mycotoxin production. Therefore, this study aimed to examine the interacting effect of i) current and increased temperature (25 vs 30 °C), ii) drought stress variation (0.98 vs 0.95 water activity; aw) and iii) existing and predicted CO2 concentrations (400 vs 1000 ppm) on fungal growth and mycotoxin production (type B trichothecenes and zearalenone) by three F. asiaticum strains (CH024b, 82, 0982) on a wheat-based matrix after 10 days of incubation. The results showed that, when exposed to increased CO2 concentration (1000 ppm) there was a significant reduction of fungal growth compared to current concentration (400 ppm) both at 25 and 30 °C, especially at 0.95 aw. The multi-mycotoxin analysis performed by LC-MS/MS qTRAP showed a significant increase of deoxynivalenol and 15-acetyldeoxynivalenol production when the CH024b strain was exposed to elevated CO2 compared to current CO2 levels. Zearalenone production by the strain 0982 was significantly stimulated by mild water stress (0.95 aw) and increased CO2 concentration (1000 ppm) regardless of the temperature. Such results highlight that intraspecies variability exist among F. asiaticum strains with some mycotoxins likely to exceed current EU legislative limits under prospected climate change conditions.

Influence of high temperature and drought stress at jointing stage on crop physiological responses and growth in summer maize plants (Zea mays L.)

The combination of low precipitation and high temperature stresses at jointing stage can severely threaten maize production. However, to date, few studies have been conducted on the effects of combined stress on maize plants expression at jointing stage. In the current research, plant growth, root morphology, and yield components were determined after exposure to the single and combined stress of high temperature and drought stress. Leaf gas exchange, malondialdehyde (MDA) content and antioxidant enzymes activities were conducted to identify potential mechanisms of stress responses. The single stress of high temperature and drought significantly reduced the biomass of various organs and the total aboveground biomass, which reduced the yield of maize plants. High temperature substantially decreased aboveground biomass and yield under mild and severe water stress, which indicated that the inhibitory effects of combined stress were more significant than that of high temperature or drought individually. High temperature exacerbated the negative impacts of water stress on plants growth and yield as shown by the reduced leaf photosynthetic rate (Pn), probably related to the increasing MDA content. Leaf-level water use efficiency (WUE) was enhanced as the reduction in leaf transpiration (Tr) was greater than the decrease in leaf photosynthesis under high temperature, even for those plants were suffering water stress. High temperature, drought stress and their combination all greatly increased the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), but were ineffective in mitigating oxidative damage. The MDA content and antioxidant enzymes activities showed an increasing trend following 12 days of combined stress. This substantiated the irreversible damage induced by combination of high temperature and desiccation stresses. The combined stress optimized roots length, root volume, root surface area, and thinned the average root diameter, which improved the adaptation of maize to high temperature, drought and combined stress. This study has provided meaningful references for improved understanding the impacts of drought, high temperature, and concurrent events on the physiology and growth of maize plants during the jointing period.

Co-inoculation of mycorrhizal fungi and plant growth-promoting rhizobacteria improve growth, biochemical and physiological attributes in Dracocephalum kotschyi Boiss. under water deficit stress.

Because of swift climate change, drought is a primary environmental factor that substantially diminishes plant productivity. Furthermore, the increased use of chemical fertilizers has given rise to numerous environmental problems and health risks. Presently, there is a transition towards biofertilizers to enhance crops' yield, encompassing medicinal and aromatic varieties. This study aimed to explore the impacts of plant growth-promoting rhizobacteria (PGPR), both independently and in conjunction with arbuscular mycorrhizal fungi (AMF), on various morphological, physiological, and phytochemical characteristics of Dracocephalum kotschyi Boiss. This experimentation took place under different irrigation conditions. The irrigation schemes encompassed well watering (WW), mild water stress (MWS), and severe water stress (SWS). The study evaluated the effects of various biofertilizers, including AMF, PGPR, and the combined application of both AMF and PGPR (AMF + PGPR), compared to a control group where no biofertilizers were applied. The findings of the study revealed that under water-stress conditions, the dry yield and relative water content of D. kotschyi Boiss. experienced a decline. However, the application of AMF, PGPR, and AMF + PGPR led to an enhancement in dry yield and relative water content compared to the control group. Among the treatments, the co-application of AMF and PGPR in plants subjected to well watering (WW) exhibited the tallest growth (65 cm), the highest leaf count (187), and the most elevated chlorophyll a (0.59 mg g-1 fw) and b (0.24 mg g-1 fw) content. Regarding essential oil production, the maximum content (1.29%) and yield (0.13 g plant -1) were obtained from mild water stress (MWS) treatment. The co-application of AMF and PGPR resulted in the highest essential oil content and yield (1.31% and 0.15 g plant-1, respectively). The analysis of D. kotschyi Boiss. essential oil identified twenty-six compounds, with major constituents including geranyl acetate (11.4-18.88%), alpha-pinene (9.33-15.08%), Bis (2-Ethylhexyl) phthalate (8.43-12.8%), neral (6.80-9.32%), geranial (9.23-11.91%), and limonene (5.56-9.12%). Notably, the highest content of geranyl acetate, geranial, limonene, and alpha-pinene was observed in plants subjected to MWS treatment following AMF + PGPR application. Furthermore, the co-application of AMF, PGPR, and severe water stress (SWS) notably increased the total soluble sugar (TSS) and proline content. In conclusion, the results indicate that the combined application of AMF and PGPR can effectively enhance the quantity and quality of essential oil in D. kotschyi Boiss., particularly when the plants are exposed to water deficit stress conditions.

Imaging of the electrical activity in the root zone under limited-water-availability stress: a laboratory study for Vitis vinifera

Abstract. Understanding root signals and their consequences for the whole plant physiology is one of the keys to tackling the water-saving challenge in agriculture. The implementation of water-saving irrigation strategies, such as the partial root zone drying (PRD) method, is part of a comprehensive approach to enhance water use efficiency. To reach this goal tools are needed for the evaluation of the root's and soil water dynamics in time and space. In controlled laboratory conditions, using a rhizotron built for geoelectrical tomography imaging, we monitored the spatio-temporal changes in soil electrical resistivity (ER) for more than a month corresponding to eight alternating water inputs cycles. Electrical resistivity tomography (ERT) was complemented with electrical current imaging (ECI) using plant-stem-induced electrical stimulation. To estimate soil water content in the rhizotron during the experiment, we incorporated Archie's law as a constitutive model. We demonstrated that under mild water stress conditions, it is practically impossible to spatially distinguish the limited-water-availability effects using ECI. We evidenced that the current source density spatial distribution varied during the course of the experiment with the transpiration demand but without any significant relationship to the soil water content changes. On the other hand, ERT showed spatial patterns associated with irrigation and, to a lesser degree, to RWU (root water uptake) and hydraulic redistribution. The interpretation of the geoelectrical imaging with respect to root activity was strengthened and correlated with indirect observations of the plant transpiration using a weight monitoring lysimeter and direct observation of the plant leaf gas exchanges.

Endophyte Inoculation Enhances Growth, Secondary Metabolites and Biological Activity of Endostemon obtusifolius Grown Under Drought Stress

There is a need to cultivate medicinal plants to meet the growing demand. Their cultivation is hampered by extreme environmental conditions such as drought that affect plant growth and its pharmacological potential. Application of stress-tolerant endophytic species may potentially attenuate these negative impacts. This study assessed the effects of individual and co-inoculation of two native endophytic species (bacterium Paenibacillus polymyxa and fungus Fusarium oxysporum) on growth, physiological responses, metabolite accumulation and therapeutic efficacy of Endostemon obtusifolius subjected to varying watering regimes (well watered, mild and severe stress) under greenhouse conditions. Drought stress negatively affected root and shoot biomass, carotenoid content, chlorophyll fluorescence and relative water content in E. obtusifolius. Electrolyte leakage and malondialdehyde and hydrogen peroxide accumulation increased with drought stress. Individual and co-inoculation endophyte treatments significantly improved growth and stress tolerance mechanisms via increased osmolyte production (soluble sugars, proline), up-regulation of the enzymatic antioxidant system (superoxide dismutase) and increased antioxidant metabolite content (total phenolics, flavonoids). Antioxidant (DPPH, FRAP) and in vitro α-glucosidase activity of ethyl acetate leaf extracts were negatively affected by water stress but significantly improved when plantlets were subjected to endophyte inoculation. The most active extracts were from plants subjected to mild water stress with co-inoculation. Thus severe drought stress negatively affected growth and therapeutic efficacy of E. obtusifolius. Inoculation with beneficial endophytes enhanced the biochemical responses, osmoregulatory network and improved the therapeutic efficacy of E. obtusifolius.

Effect of Two Biostimulants, Based on Ascophyllum nodosum Extracts, on Strawberry Performance under Mild Drought Stress

The world’s population continues to grow while available natural resources, such as arable land, water, and quality soil, are decreasing. Therefore, it is essential to implement environmentally friendly crop management strategies, which include the use of biostimulants. This study analysed the effects on strawberry plants of ActyseiTM and Phylgreen®, two commercial biostimulants based on extracts of the seaweed Ascophyllum nodosum. The study was conducted under field capacity (regular irrigation) and at 50% field capacity (mild water stress conditions) for 12 weeks. Different growth parameters of the aerial parts of the plants were measured weekly, such as the number of leaves, length of the longest leaf, leaf area, and the number of flowers and fruits produced, as well as the chlorophyll content, determined with a single-photon avalanche diode (SPAD) detector. At the end of the experiment, the plant material was collected, and the roots and aerial parts were weighed separately to obtain the fresh and dry weight of the samples. Fruit quality was assessed by analysing morphological parameters (weight and size) and some biochemical variables (proline, total soluble sugars, and antioxidant compounds contents). ActyseiTM application generally enhanced plant growth in control plants and under mild water stress conditions, even though root weight was reduced. In contrast, no significant effect of Phylgreen® on vegetative growth was observed, except for stimulating the root growth of plants watered at field capacity. Both biostimulants, Phylgreen® to a greater extent, showed an impact on the plants already seven weeks after their initial application, stimulating flower and fruit production, especially at field capacity.

Water stress significantly affects the diurnal variation of solar-induced chlorophyll fluorescence (SIF): A case study for winter wheat

Remote sensing of Solar-induced chlorophyll fluorescence (SIF) has been widely used in estimating Gross Primary Productivity (GPP) and detecting stress in terrestrial ecosystems. Water stress adversely impacts the growth, development, and productivity of a plant. Recently, the characterizing and understanding of the diurnal cycling of plant functioning and ecosystem processes has been explored using SIF. However, the diurnal response of SIF to different levels of water stress remains unclear. This study conducted field experiments on winter wheat by subjecting it to different levels of water stress including well-watered (CK) and, mild, moderate, and severe water stress (D1, D2, D3), and collected the spectral data using an automated SIF measurement system. The results observed the strong SIF-PAR (photosynthetically active radiation) correlations and that these relationships gradually decoupled with increasing water stress, which further decreased the accuracy of temporal upscaling of far-red SIF from an instantaneous to daily scale. To quantify the characteristics of diurnal far-red SIF, five indices including peak time, peak value, curve opening coefficient (leading coefficient of the parabola), and left/right slopes of the peak were proposed. The results demonstrated that diurnal far-red SIF was characterized by an earlier peak time, decreasing peak value, wider curve opening, and flattening right slope from the CK plot to the D3 plot. There were certain mechanisms linking the different indices, for example, between peak size and opening coefficient. Furthermore, the response of far-red SIF to water stress was most pronounced at noon. SIF/PAR exhibited a more significant response to varying water stress compared to far-red SIF, which mitigated the negative influence of PAR variations on diurnal SIF. These findings contribute to the monitoring of plant water dynamics at fine temporal scales.

Changes induced by multi-stage water stress on maize growth, water and nitrogen utilization and hormone signaling under different nitrogen supplies

Water availability and nitrogen (N) supply are two major issues that affect plant productivity, however, the processes of water and N utilization and their hormone regulation are not conclusive in response to varying water-N interaction. The objective of this study was to evaluate the effects of water stress (WS) at different growth stages on maize plant development, root morphology, water utilization, hormone signaling and N accumulation under various N conditions. A set of controlled drought stress at 60% field capacity was conducted from bell (V12) to tassel (VT) stage (V12-VT, denoted as W1W2), from silk (R1) to milk (R3) stage (R1-R3, denoted as W2W1) and their compound stages (V12-R3, denoted as W1W1) under high- and low-N supply, respectively. The results indicated that compared to the well-watered control (W2W2), W2W1 reduced root length, root area, and shoot dry matter by 4.68–19.15%, 5.92–11.97% and 4.38–29.61%, respectively, while W1W2 promoted the root system and improved the shoot growth, grain formation and plant water use efficiency (WUEp). High N supply tended to aggravate WS with a poorer root system and lower leaf water potential (ψleaf) but higher leaf abscisic acid (ABA) accumulation at different growth stages. Leaf ABA significantly increased while stomatal conductance (Gs) decreased under WS and N-rich environment, hence increasing leaf intrinsic water use efficiency (WUEi). Root zeatin-riboside (ZR) was higher for well-watered and N-rich conditions. Moreover, leaf ABA significantly increased with the decrease of ψleaf (R2 =0.51 for R3, R2 =0.35 for dough stage (R4)) and the variation of ψleaf was relatively constant (≤0.3 MPa) with different water treatments, indicating that maize performed isohydric behavior to response water stress and N-rich environment. This study suggests that to promote the potential of water- and N-saving and improve crop productivity in maize cultivation, mild water stress at vegetative growth stages and appropriate N supply are of great importance.

Determination of Yield and Quality Parameters in Pickling Hot Peppers Grown under Different Water Stress Conditions

Plants are exposed to various adverse environmental conditions throughout their growth period. In recent years, drought, which has occurred and necessitated different measures, ranks among these adverse conditions. At the same time, plants synthesize certain biochemical compounds in response to the adverse conditions they will encounter. These compounds not only strengthen the immune system but also provide resistance against various diseases, and they tend to increase under adverse environmental conditions that plants will face during cultivation. This study was conducted to determine the changes in yield and some biochemical components in pickling hot peppers (Capsicum Annuum L.) grown under different water stress conditions. Two different levels of water stress (%70 and %30 irrigation) were applied in addition to full irrigation (%100 irrigation). At the end of the research, while a yield of 269.42 g per plant was obtained in the control group (%100 irrigation), 150.14 g and 93.33 g of pickling hot peppers were harvested in each water stress treatment, respectively. Total phenolic compound levels increased with water stress; it was determined to be 0.827 mg-1g in the trial irrigated with full irrigation water, 1.170 mg-1g in plants exposed to mild water stress, and up to 1.536 mg-1g in the trial subjected to severe water stress. In addition, total flavonoids and antioxidant compound levels also increased with increasing water stress. The amounts of flavonoid compounds obtained from the trial groups were 0.146, 0.373, and 0.412 mg-1g, respectively, while the antioxidant levels determined by the DPPH method increased in quantity with increasing water stress, similar to other biochemical compounds. According to these results, it was determined that the yield of pickling hot peppers decreased in the case of water shortage that the plants would face in cultivation, but there was an increase in some biochemical compounds.

Evaluation for Multiple Abiotic Stress Tolerance in Rice (Oryza Sativa) Genotypes

Abiotic stresses are the major constraints that affect the morphological, physiological and biochemical attributes of plants resulting in reduction of yield. Recently, combined occurrence of stresses has become a greater cause of concern in farmers’ fields. Hence, there is a need to identify genotypes that are tolerant to more than one stress. A study on physiological characterization for water and salinity stress was conducted in twenty rice genotypes during kharif 2022 at Regional Agricultural Research Station, Maruteru, Andhra Pradesh, India. Results showed that among all the treatments, root length, shoot length, root and shoot dry weight and chlorophyll content were greater under control followed by 1% mannitol, 2% mannitol and salinity stress. Visual scoring for water stress at seedling stage revealed that under mild water stress (1% M) in genotypes viz., CR4423-8, FL 478 and Pantara recorded 75-90% of survival and under severe water stress (2% M) 40-50% survival. Under salinity stress, the score 3 was recorded in FL 478 and 5 in Naveen, Pantara and CR 4423-75. For combined stresses, FL 478 and Pantara were identified as tolerant and can be suggested as donors.

Impact of Mild Water Stress During the Flowering Stage on Leaf Functional Traits and Yield of Selected Cowpea Varieties Grown in The Low Country Dry Zone of Sri Lanka

Impact of Mild Water Stress During the Flowering Stage on Leaf Functional Traits and Yield of Selected Cowpea Varieties Grown in The Low Country Dry Zone of Sri Lanka

Response of Water Stress and Bacterial Fertilizer Addition to the Structure of Microbial Flora in the Rhizosphere Soil of Grapes Under Delayed Cultivation

ABSTRACT The objectives of this study were to reveal the soil microbial structures in the rhizosphere soil of the delayed cultivation and to evaluate the effects of water stress and bacterial fertilizer on major bacteria. The experiment was conducted in 2019 in Yongdeng County, Gansu Province. Three treatments of water regulation were set, including the moderate water stress, mild water stress and adequate water supply treatment with the bacterial fertilizer added at the levels of no addition (0 g), small addition (75 g) and large addition (150 g), respectively. The results showed that the relative abundance of dominant species of soil microorganisms was significantly higher under sufficient water supply and mild water stress treatment than under moderate water stress treament. Under the mild water stress condition, the relative abundance of the most dominant species in each classification level sequentially decreased with the bacterial fertilizer added increasingly. Adding a small amount of bacterial treatment fertilizer to moderate water stress can improve the overall abundance of soil microbial communities during the growth period of new shoots. It was found that Proteobacteria, Bacteroidetes, Gemmatimonadetes, Actinobacteria, Firmicutes, Acidobacteria, Chloroflexi, Planctomycetes, Thaumarchaeota, Verrucomicrobia, and the other bacteria were the major bacterial phyla in the rhizosphere soil of delayed cultivation grapes, among, which Proteobacteria were the most dominant group. Therefore, adding a small amount of bacterial fertilizer under the mild water stress treatment can not only improve the diversity and richness of soil microorganisms during the fruit expansion period, but also significantly save water resources compared with the traditional irrigation regimes.

Organ-specific responses during acclimation of mycorrhizal and non-mycorrhizal tomato plants to a mild water stress reveal differential local and systemic hormonal and nutritional adjustments

Main conclusionTomato plant acclimation to a mild water stress implied tissue-specific hormonal and nutrient adjustments, being the root one of the main modulators of this response.Phytohormones are key regulators of plant acclimation to water stress. However, it is not yet clear if these hormonal responses follow specific patterns depending on the plant tissue. In this study, we evaluated the organ-specific physiological and hormonal responses to a 14 day-long mild water stress in tomato plants (Solanum lycopersicum cv. Moneymaker) in the presence or absence of the arbuscular mycorrhizal fungus Rhizoglomus irregulare, a frequently used microorganism in agriculture. Several physiological, production, and nutritional parameters were evaluated throughout the experiments. Additionally, endogenous hormone levels in roots, leaves, and fruits at different developmental stages were quantified by ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC–MS/MS). Water deficit drastically reduced shoot growth, while it did not affect fruit production. In contrast, fruit production was enhanced by mycorrhization regardless of the water treatment. The main tissue affected by water stress was the root system, where huge rearrangements in different nutrients and stress-related and growth hormones took place. Abscisic acid content increased in every tissue and fruit developmental stage, suggesting a systemic response to drought. On the other hand, jasmonate and cytokinin levels were generally reduced upon water stress, although this response was dependent on the tissue and the hormonal form. Finally, mycorrhization improved plant nutritional status content of certain macro and microelements, specially at the roots and ripe fruits, while it affected jasmonate response in the roots. Altogether, our results suggest a complex response to drought that consists in systemic and local combined hormonal and nutrient responses.

Determination of Water Stress in Wheat Crops by Thermal Images Under Mediterranean Conditions

ABSTRACT Canopy temperature is used as an indicator of plant water stress. In recent years, technological advances have allowed improved applications in agriculture from temperature sensors clamped on leaves to short-range remote-sensing, such as infrared thermometry and thermal imaging. There are many scientific studies on the use of thermal imaging to determine crop water stress; however, no study on wheat crops has been found in the literature. Therefore, this study aimed to determine the detectability of water stress in wheat by using thermal images. In the experiment, drainage-type, weighable lysimeters were used to make precise irrigations and obtain components of the water budget for calculating the plant water consumption. Wheat crops were grown under four different irrigation levels including no water stress as control (I100), mild water stress (I75), moderate water stress (I50), and severe water stress (I25). When the thermal images were examined, it can be seen that pre-irrigation images reflect water stress conditions better than post-irrigation. The warm color distribution was more evident under severe water stress, whereas cold colors were dominant under no water stress. During the experimental period, the plant leaf temperatures varied from 17.5 to 34.2°C, while the spike temperatures ranged from 26.6°C to 36.3°C. The lowest plant leaf and spike temperature values were observed under control, whereas the highest values were obtained under severe water stress. It can be said that thermal cameras that provide fast and contactless data acquisition have the potential to be used in detecting water stress in wheat crops.