Levels Of Water Stress Research Articles

Accurate estimation of sorghum crop water content under different water stress levels using machine learning and hyperspectral data.

This study investigates the effects of different water stress levels on spectral information, leaf area index (LAI), and the performance of three machine learning (ML) algorithms in estimating crop water content (CWC) of sorghum. The results show that the spectral reflectance of sorghum varies with growth stage and irrigation treatment, but consistent patterns are observed for each treatment. The LAI of sorghum gradually increased throughout the growth stages, with the most significant variation observed during the flowering stage. In this study, three machine learning-based regression models, namely, extreme gradient boosting (XGBoost), random forest (RF), and support vector machine (SVM), were utilized to estimate sorghum CWC using hyperspectral measurements. Recursive feature elimination (RFE) method was used to select the optimal spectral reflectance wavelengths for the ML models, and principal component analysis (PCA) was used to reduce the dimensionality of the hyperspectral data. The results indicated that the RF model achieved the highest R2 (0.90) and lowest of RMSE (56.05) value using selected wavelengths, while the XGBoost model demonstrated superior accuracy and reliability in estimating CWC using dimensionality-reduced hyperspectral data (r = 0.96, RMSE = 45.77). Also, the study highlights the importance of vegetation index (VI) in CWC estimate. Some VIs, such as NDVI and MSAVI, performed poorly, while others, such as CL_Rededge and EVI, performed better. The study provides valuable insights into the effects of water stress levels on spectral information, LAI, and the performance of ML algorithms in estimating the CWC of sorghum. The findings have significant implications for precision agriculture, as accurate and reliable estimates of CWC can help farmers optimize irrigation and fertilizer applications, leading to improved crop yields and resource efficiency.

Influence of sustained deficit irrigation and foliar kaolin application on almond kernel composition

Deficit irrigation and kaolin foliar application are agronomic practices that have been demonstrated to improve productivity and physiological response in almond trees but there is no consistent information on the effects on the kernel composition. The objective of this study was to evaluate the effect of different Sustainable Deficit Irrigation (SDI) strategies and kaolin application on some physicochemical composition of the cv Ferragnès almond (Prunus dulcis (Mill.) D.A. Webb). A randomized block design with five treatments was developed: non-irrigation (NI), non-irrigation with foliar kaolin application (NI+K), full irrigation (FI), and two levels of SDI receiving 70% and 35% of evapotranspiration (SDI75 and SDI35). Pomological parameters, volatile profile and oil composition were analyzed. SDI effect on kernel weight was reduced against full irrigation (FI) but substantially improved in comparison with the rainfed treatments (NI and NI+K). Irrigation treatments showed a lower volatile compounds concentration in comparison with rainfed treatment. The fatty acid composition of the oil was significantly affected, with all the irrigated treatments having higher oleic acid contents than the rainfed treatments, and therefore an expected increased shelf life. Kaolin application had no positive effects on the non-irrigated trees, other than an apparent increase in the total volatiles, a tendency also observed in the NI. Moderate water stress levels (SDI35) improved the synthesis of tocopherols compared to NI, FI and SDI70, which could be related to the adaptation of the almond tree to drought. SDI35 is therefore regarded as a very interesting approach, with significant improvements in comparison with non-irrigated trees, and a clear saving on water against full irrigation without significant pomological and chemical alterations.

Regional Water Stress Forecasting: Effects of Climate Change, Socioeconomic Development, and Irrigated Agriculture—A Texas Case Study

Climate change, socioeconomic development, and irrigation management are exacerbating water scarcity in many regions worldwide. However, current global-scale modeling approaches used to evaluate the impact of these factors on water resources are limited by coarse resolution and simplified representation of local socioeconomic and agricultural systems, which hinders their use for regional decision making. Here, we upgraded the irrigation water use simulation in the system dynamics and water environmental model (SyDWEM) and integrated it with the water supply stress index (WaSSI) ecosystem services model. This integrated model (SyDWEM-WaSSI) simulated local socioeconomic and agricultural systems to accurately assess future water stress associated with climate change, socioeconomic development, and agricultural management at subbasin levels. We calibrated the integrated model and applied it to assess future water stress levels in Texas from 2015 to 2050. The water stress index (WSI), defined as the ratio of water withdrawal to availability, was used to indicate different water stress levels. Our results showed that the integrated model captured changes in water demand across various sectors and the impact of climate change on water supply. Projected high water stress areas (WSI > 0.4) are expected to increase significantly by 2050, particularly in the Texas High Plains and Rolling Plains regions, where irrigation water use was projected to rise due to the impact of climate change. Metropolitan areas, including Dallas, Houston, Austin, and San Antonio, were also expected to experience increased domestic water demand, further exacerbating water stress in these areas. Our study highlights the need to incorporate socioeconomic planning into water resources management. The integrated model is a valuable tool for decisionmakers and stakeholders to evaluate the impacts of climate change, socioeconomic development, and irrigation management on water resources at the local scale.

Assessing Climate-Driven Salinity Intrusion through Water Accounting: A Case Study in Ben Tre Province for More Sustainable Water Management Plans

This scientific paper delves into sustainable water management strategies for Ben Tre Province of the Vietnamese Mekong Delta (VMD) in light of water-infrastructure plans that have been impacted by climate change-induced salinity intrusion. Specifically, we aim to mitigate the effects of salinity intrusion for the province while promoting long-term environmental sustainability. In doing so, a water accounting framework was applied, mostly based on the MIKE11 hydrodynamic modeling and water balance calculations, to determine current and future water stress issues based on two main scenarios of extreme drought year 2016 (baseline) and the future year 2030 under climate change for a medium-low emission scenario (RCP4.5). The study found that salinity intrusion significantly causes severe water stress in the future year 2030 compared to the baseline year 2016, while the existing water management methods are relatively inadequate to control salinity intrusion, leading to over 57% of the area affected by medium to critical water stress levels, although it will go along with planned water infrastructures. Additionally, a system of triple rice cropping converted two rice cropping and upland cropping with 40% water demand cutoff was found to be the most suitable measure for 2030. Particularly, water-saving and water demand reduction should be incorporated into infrastructural planning for sustainable water management. Our study provides valuable insights for policymakers and stakeholders, not only for the province and the VMD, but also other regions facing similar challenges.

A tug of war between centralization and decentralization: the co-evolution of urban governance and water risks in Guwahati, India

Intermediate cities in Asia and Africa house more than 60% of the world’s urban population. More than 54% of the people here face high levels of water stress and are increasingly vulnerable to water-related risks such as floods, limited access to safe drinking water and water pollution. These urban water risks are complex outcomes of climate change, land use changes, governance failures, and social inequities. This study examines the co-evolution of three water risks and governance responses through the case of Guwahati, India. Guwahati, on the Brahmaputra River in the Northeast of India, serves as a case of an intermediate city to demonstrate changes in water risk governance trends. We focus on studying the connected governance responses to changes in three interrelated water risks, i.e., domestic water supply, urban floods, and river pollution. The shifts in the socio-political structures for these risks are assessed by combining historical institutionalism with multi-level perspective theory. The results show that despite the growing diversity of actors and devolution of responsibilities in cities to mitigate water risks, there is an ongoing tug-of-war between centralized and decentralized modes of decision-making. Contrary to the recommendations for decentralized urban governance, the trend is currently tugging towards a centralized decision-making mode. However, when differences arise between the local and national, local actors within their limited frames of action manage to circumnavigate nationally dictated mandates to fit local needs.

Methodology for a preliminary assessment of water use sustainability in industries at sub-basin level

The sustainability of industrial production, especially for highly water-demanding processes, is strictly related to water resource availability and to the dynamic interactions between natural and anthropogenic requirements over the spatial and temporal scales. The increase in industrial water demand raises the need to assess the related environmental sustainability, facing the occurrence of global and local water stress issues. The identification of reliable methodologies, based on simple indices and able to consider the impact on local water basins, may play a basilar role in water sustainability diagnosis and decision-making processes for water management and land use planning. The present work focalized on the definition of a methodology based on the calculation of indicators and indices in the view of providing a synthetic, simple, and site-specific assessment tool for industrial water cycle sustainability. The methodology was built starting from geo-referenced data on water availability and sectorial uses derived for Italian sub-basins. According to the data monthly time scale, the proposed indices allowed for an industrial water-related impacts assessment, able to take into account the seasonal variability of local resources. Three industrial factories, located in northern (SB1, SB2) and central (SB3) Italian sub-basins, were selected as case studies (CS1, CS2, CS3) to validate the methodology. The companies were directly involved and asked to provide some input data. The methodology is based on the calculation of three synthetic indexes: the Withdrawal and Consumption water Stress Index (WCSI) allowed for deriving a synthetic water stress level assessment at the sub-basin scale, also considering the spatial and temporal variations; the industrial water use sustainability assessment was achieved by calculating the Overall Factory-to-Basin Impact (OFBI) and the Internal Water Reuse (IWR) indices, which allowed a preliminary evaluation of the factories' impacts on the sub-basin water status, considering the related water uses and the overall pressures on the reference territorial context. The WCSI values highlighted significant differences between the northern sub-basins, characterised by limited water stress (WCSISB1 = 0.221; WCSISB2 = 0.047), and the central ones, more subjected to high stress (WCSISB3 = 0.413). The case studies CS1 and CS3 showed to exert a more significant impact on the local water resource (OFBICS1 = 0.18%; OFBICS2 = 0.192%) with respect to CS2 (OFBI = 0.002%), whereas the IWR index revealed the different company's attitude in implementing water reuse practices (IWRCS1 = 40%; IWRCS1 = 27%; IWRCS1 = 99%). The proposed methodology and the indices may also contribute to assessing the effectiveness of river basin management actions to pursue sustainable development goals.

Impact of water stress on the demographic traits and population projection of Colorado potato beetle.

Introduction: The Colorado potato beetle is one of the famous quarantine pests in China which is extremely destructive to Solanaceae crops and causes serious losses to the potato industry. Methods: In this experiment, the host plant potato was subjected to different degrees of water stress to observe the oviposition selection, growth and development, survival, reproduction and population growth of Colorado potato beetles. Results: The results showed that adult Colorado potato beetles laid more eggs on potato plants suitable for water treatment, but fewer eggs on potato plants treated with water stress. The developmental duration of Colorado potato beetles in light drought treatment was shorter than that in control treatment, and the survival rate was higher than that in control treatment. With the aggravation of water stress, the developmental duration was prolonged, survival rate was decreased, and the number of eggs was decreased. Under different water stress levels, the intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R 0), and mean generation time (T) of the Colorado potato beetle population were significantly lower than those of control treatment, but there was no significant difference between light drought and control treatment. The TIMING-MS Chart program was used to predict the population dynamics of Colorado potato beetle for 110days, which showed the fastest population growth in CK treatments and the slowest in HD treatments. The reduced water content of the leaves also reduces the survival rate of adult Colorado potato beetles. The growth, development, survival, and reproduction of Colorado potato beetles are affected by water stress of host plants. Moderate and heavy droughts have negative effects on the development and reproduction of Colorado potato beetles. Discussion: This information can be used to clarify the impact of water stress on the growth, development and population dynamics of Colorado potato beetle, to provide a theoretical basis for the control of this pest.

Transcriptome and metabolites analysis of water-stressed grape berries at different growth stages.

Drought is one of the main abiotic factors affecting grape quality. However, the impacts of drought stress on sugar and related gene expression during grape berry ripening remain unclear. In this experiment, the grapes were subjected to different levels of continuous water stress from 45 to 120 days after flowering (DAA) to study the changes in berry sugar content and the expression of genes related to sugar metabolism under different water stresses. Data supported that glucose, fructose, sucrose, and soluble sugars increased from 45 DAA. Combined with previous research results, T1, T2, and Ct grape berries with 60 ~ 75 DAA and large differences in sucrose, fructose, glucose and soluble sugars compared with the Ct were selected for RNA sequencing (RNA-seq). Through transcriptome analysis, 4471 differentially expressed genes (DEGs) were screened, and 65 genes in photosynthesis, ABA signaling pathway and photosynthetic carbon metabolism pathway were analyzed further by qRT-PCR. At 60 DAA, the relative expression levels of CAB1R, PsbP, SNRK2, and PYL9 were significantly upregulated in response to water stress, while AHK1, At4g02290 were down-regulated. At 75 DAA, the relative expression levels of ELIP1, GoLS2, At4g02290, Chi5, SAPK, MAPKKK17, NHL6, KINB2, and AHK1 were upregulated. And CAB1R, PsbA, GoLS1, SnRK2, PYL9, and KINGL were significantly downregulated under moderate water stress. In addition, PsbA expression was down-regulated in response to water stress. These results will help us to fully understand the potential connections between glucose metabolism and gene expression in grapes under drought stress.

Water and sludge resource planning for sustainable agriculture: An energy-water-food-waste nexus approach

The population rise and expected increase in global food demand will stress natural freshwater resources. It will also result in increased emissions if proper resource planning is not implemented and unconventional water and energy resources are not exploited. There is a need to assess the potential of these unconventional resources, such as wastewater and sludge in alleviating carbon emissions and water stress. This study aims to do so by assessing the use of treated wastewater and sludge for food production and optimizing their planning using a multi-objective optimization model embedded within an energy-water-food-waste nexus approach applied to a case study on the agricultural sector in the state of Qatar. It is demonstrated that the use of treated sewage effluent as a water resource can supply the fodder farms in Qatar with all their nitrogen fertilization requirements almost throughout the year. Furthermore, the use of both treated sewage effluent and sludge as a source of energy has the potential to reduce the carbon footprint and water stress level by 62 % and 57 %, respectively. It is thus recommended to include treated sewage effluent in the agricultural water budget and to suspend outdoor farming not only during the summer but also in the hot month of March, as the latter can result in an additional 7 % and 30 % reduction of carbon footprint compared to the base-scenario when the water stress level is set to 0 % and 75 %, respectively.

The response of oil palm seedlings' growth to vermicompost and water stress under the main nursery stage

The availability of nutrients and water are two things that are essential for the development of plants. Future oil palm agriculture will require a strategy for the management of water because of the erratic nature of the weather. The addition of organic matter, such as vermicompost, is one strategy for addressing the issue of insufficient water supplies. The primary objective of this study is to investigate the relationship between oil palm seedlings' exposure to vermicompost and various levels of water stress in the main nursery. During the three-month study, 100, 200, and 300 g of vermicompost per polybag was combined with 1.0, 1.5, and 2.0 L/polybag/day. There was no relationship between the dose of vermicompost and the water stress that had observed. The addition of 300 g/polybag of vermicompost increased root fresh weight by 37.8% compared to 100 g/polybag. Moreover, water stress leads to a reduction in plant height and dry weight of the shoots. Compared to 2 L/polybag/day, plant height was lowered by 23.3% and 19.8% at watering volumes of 1.0 and 1.5 L/polybag/day, respectively. In addition, when compared to the appropriate water level of 2 L/polybag/day, high water stress (1.0 L/polybag/day) declined shoot dry weight by 12%.

Response of different substrates and irrigation water levels on yield and oil quality of ginger grown in greenhouse

Growing media and irrigation water level are the most important factors affecting plant yield and quality throughout the world. The present research was conducted in greenhouse located in Batı Akdeniz Agricultural Research Institute between 2019 and 2020 growing season to determine the effects of different substrates and irrigation levels on yield and phenolic and essential oil compounds of ginger (Zingiber officinale). In this research, in order to investigate the effects of different substrates and irrigation levels on physiological characteristics and yield of ginger, an experiment was conducted as factorial, in which the main factor was three substrates (S1: 75% cocopeat + 25% perlite, S2: 50% peat + 50% perlite, and S3: 25% zeolite + 75% peat) and the sub factor was four irrigation levels, I1:100% I2: 75%, I3: 50%, and I4:25% were applied experimental plots according to the daily solar radiation values reaching the greenhouse, with 3 replications. Evapotranspiration values ranged between 49.7-198.7 L plant-1 and 51.7-206.9 L plant-1 in 2019 and 2021 years, respectively. Rhizome fresh weight values for S1, S2, S3 and S4 were determined as134.8, 94.7, 71.2 and 31.1 g in 2019 and 164.5, 148.1, 95.1 and 74.9 g in 2020, respectively. Water deficit stress significantly (P ≤ 0.01) increased 6-gingerol, 6-shogaol, α-zingiberene, α-farnesene, and geranly-acetate contents while it decreased β-sesquiphellandrene and β-bisabolene content. It is concluded that essential oil yield of ginger decreased depending on the increasing irrigation water stress levels.

The Influence of Induced Drought Stress on Germination of Cenchrus ciliaris L. and Cenchrus setigerus Vahl.: Implications for Rangeland Restoration in the Arid Desert Environment of Kuwait

Drought impacts in arid desert ecosystems can result in decreased ecosystem productivity and biodiversity. Implementation of restoration projects in arid desert environments is largely dependent on water availability and soil moisture condition. This study investigated the influence of induced drought stress by using polyethylene glycol (PEG-6000) solution on germination viz. Cenchrus ciliaris and Cenchrus setigerus as the important rangeland species. The water stress potential treatments were 0 (control), –0.5 MPa, –1.0 MPa, –1.5 MPa, and –2.0 MPa. The extent of seed germination was severely affected by decreased water stress potential. As drought increased, the percentage of germination decreased in both Cenchrus’ species. The water deficit at –0.5 MPa showed a significant (P < 0.001) reduction in the final germination percentage in the case of C. setigerus and C. ciliaris by 65% and 42.5%, respectively. At –1.0 MPa to –1.5 MPa, changes in intermediate germination were observed in C. ciliaris (from 35% to 17.5%, respectively) and C. setigerus (from 22.5% to 11.25% respectively). Higher levels of water stress (–2.0 MPa) prevented the survival of both species. Understanding the germination strategies of native desert plant species associated with drought stress and identifying favorable conditions during the germination process can be useful for restoration practices and rangeland management actions to improve desert ecosystems and maintain biodiversity.

Influence of Watering Regimes on Physiological Traits, Growth, Yield, and Capsaicin Content of Chilies

Water stress is a major limiting factor affecting the physiological processes, growth, and productivity of crop plants, including chili. This study evaluated chili plants' responses regarding physiological traits, growth, yield, and capsaicin content under different irrigation levels. The experimental design was a 2x4 factorial in CBD. A pot experiment was conducted on two species of chilies: Capsicum annuum ‘Super-Hot 2’ and ‘Huay-Siiton’ and C. frutescent ‘Prik-Kee-Nu-Suan.’ The plants were irrigated at four watering regimes such as 100%, 80%, 60%, and 40% of maximum water holding capacity (MWHC) after the anthesis through fruit development. Midday leaf water potential (LWPmd) was ranked between -1.30 MPa in 100% MWHC to -2.11 MPa in 40% MWHC indicating the level of water stress. The 40% MWHC caused a drastic decrease in LWPmd and reduced the maximum quantum yield of PSII (Fv/Fm) and growth rate in canopy width. Observed leaf greenness was maximized at 60% MWHC. The irrigation regimes also affected the yield of chili, especially the 60% and 40% MWHC, with a reduced number of fruits/plant, fruit fresh and dry weights, and fruit sizes. In the case of 40% MWHC, the dry yield was too low, and it was impossible to analyze the capsaicin content. The reduced irrigation (80% and 60% MWHC) did not significantly induce the capsaicin content or pungency of the studied chili cultivars. Thus the capsaicin yield of studied chili cultivars was reduced considerably by severe reduction of dry fruit yield under restricted water.

Responses of dry matter accumulation and partitioning to drought and subsequent rewatering at different growth stages of maize in Northeast China.

Dry matter accumulation (DMA) and dry matter partitioning (DMP) are important physiological processes determining crop yield formation. Deep understanding of the DMA and DMP processes and their responses to drought are limited by difficulty in acquiring total root biomass. Pot experiments with treatments quitting and ceasing ear growth (QC) and controlling soil water (WC) during vegetative (VP) and reproductive (RP) growth stages of maize (Zea mays) were conducted in Jinzhou in 2019 and 2020 to investigate the effects of drought and rewatering on DMW and DMP of different organs. The response of DMW of reproductive organ to drought was more sensitive than those of vegetative organs, and was maintained after rehydration. Drought during VP (VPWC) reduced more sharply DMW of stalk than of leaves, and that during RP (RPWC) decreased more substantially leaves DMW. The effect of drought on DMPR was inconsistent with that on DMW for each organ. The DMP patterns of maize in different growth stages have adaptability to some level of water stress, and their responses increased with drought severity. Drought increased significantly DMP rates (DMPRs) of vegetative organs and reduced the ear DMPR and harvest index (HI), attributing to the suppressed photosynthates partitioning into ear and dry matter redistribution (DMRD) of vegetative organs, especially for stalk DMRD decreasing 26%. The persistence of drought impact was related to its occurrence stage and degree as well as the duration during rewatering to maturity. The aftereffect of drought during different growth periods on DMP were various, and that of VPWC enlarged and drastically induced the reduction of HI, also was larger than that of RPWC which demonstrated obvious alleviation in the previous responses of DMP and HI. Root-shoot ratio (RSR) increased under VPWC and RPWC and subsequent rehydration. The DMWs of stalk, roots and leaves were affected by VPWC in order from large to small, and were close to or larger than the controls after rehydration, indicating the compensation effect of rewatering after drought. The DMPRs, RSR AND HI are the important parameters in agricultural production, and are often used as the constants, but in fact they vary with plant growth. In addition, the interannual differences in ear and stalk DMPRs in response to drought were probably caused by the difference in degree and occurrence stage of drought, further reflecting the variation in response of allometry growth among organs to the environment. Besides, the persistence of drought impact was related to the occurrence stage and degree of drought, which is also associated with the duration during rewatering to maturity. Notably, the effect of drought on DMW was inconsistent with that on DMPR for each organ meaning that the two variables should be discussed separately. The QC did not affect total DMW but increased RSR, changed and intensified the effect and aftereffect of RPWC on DMP, respectively, indicating that the DMP pattern and its response to drought occur change under the condition of QC.

Precise control of water stress in the field reveals different response thresholds for forage yield and digestibility of maize hybrids.

With dwindling global freshwater supplies and increasing water stress, agriculture is coming under increasing pressure to reduce water use. Plant breeding requires high analytical capabilities. For this reason, near-infrared spectroscopy (NIRS) has been used to develop prediction equations for whole-plant samples, particularly for predicting dry matter digestibility, which has a major impact on the energy value of forage maize hybrids and is required for inclusion in the official French catalogue. Although the historical NIRS equations have long been used routinely in seed company breeding programmes, they do not predict all variables with the same accuracy. In addition, little is known about how accurate their predictions are under different water stress-environments. Here, we examined the effects of water stress and stress intensity on agronomic, biochemical, and NIRS predictive values in a set of 13 modern S0-S1 forage maize hybrids under four different environmental conditions resulting from the combination of a northern and southern location and two monitored water stress levels in the south. First, we compared the reliability of NIRS predictions for basic forage quality traits obtained using the historical NIRS predictive equations and the new equations we recently developed. We found that NIRS predicted values were affected to varying degrees by environmental conditions. We also showed that forage yield gradually decreased as a function of water stress, whereas both dry matter and cell wall digestibilities increased regardless of the intensity of water stress, with variability among the tested varieties decreasing under the most stressed conditions. By combining forage yield and dry matter digestibility, we were able to quantify digestible yield and identify varieties with different strategies for coping with water stress, raising the exciting possibility that important potential selection targets still exist. Finally, from a farmer's perspective, we were able to show that late silage harvest has no effect on dry matter digestibility and that moderate water stress does not necessarily result in a loss of digestible yield.

Integrated Effects of Water Stress and Plastic Film Mulch on Yield and Water Use Efficiency of Grain Maize Crop under Conventional and Alternate Furrow Irrigation Method

Water scarcity in arid regions increases the need for technologies to improve water productivity. The integrated effects of plastic film mulching and water stress on grain maize under conventional and alternate furrow irrigation methods are still poorly understood in Sindh’s climate. Therefore, field trials were conducted at Malir farm, Sindh Agriculture University Tandojam, Pakistan, during the cropping season 2020–2021 to investigate whether mulching is practicable for grain maize production under the different furrow irrigation methods. The experiments involved two types of furrow irrigation, two water stress levels (sufficient and severe water stress), and plastic film mulching. Treatments were laid out in a randomized block design and three replications. The conventional and alternate furrow irrigation method was assigned to the main plot, while the water stress and plastic film mulching were in sub-plots. The results showed that different furrow irrigation methods significantly affected plant growth, grain yield parameters, and crop harvest index. Significant highest plant growth and grain yield of maize crop were observed with the conventional furrow irrigation (CFI) compared with the alternate furrow irrigation (AFI) method. However, grain yield and irrigation water productivity (IWP) were increased significantly by the plastic film mulching. The results revealed that sufficient water stress was more effective in sustaining grain yield and IWP than crop irrigating at several water stresses. The interaction effect of furrow irrigation and water stress, furrow irrigation, and plastic film mulching significantly impacted the IWP of grain maize. The IWP of the maize crop was significantly higher under the AFI than the CFI method if it was mulched with plastic film and irrigated at sufficient water stress level.

Effects of Water Stress on Resveratrol Accumulation and Synthesis in ‘Cabernet Sauvignon’ Grape Berries

Resveratrol (3, 4′, 5 trihydroxy stilbene) is a natural phytoalexin produced by plants in response to biotic and abiotic stresses. It is well known for its cardio-protective, anticarcinogenic, and antioxidant properties. This study characterized physiological and molecular changes in resveratrol synthesis exposed to two levels of water stress at distinct grape berry developmental stages. Physiological data were measured to assess the berry quality. We used high-performance liquid chromatography to study enzyme activity and qRT-PCR to assess the expression levels of genes involved in resveratrol synthesis. The berry development was suppressed under water stress, while the content of total polyphenol, especially resveratrol was enhanced. Related enzymes and genes regulate the changes in resveratrol in plants. Water stress improved the enzyme activities of PAL (phenylalanine ammonia-lyase) and STS (stilbene synthase) after veraison. Moreover, the transcription factors VvMYB14, VvMYB15 and resveratrol synthesis-related genes are also changed. Expression of Vv4CL and VvMYB15 were upregulated during the pre-reversion stage, whereas VvPAL and VvSTS increased throughout development. As the co-substrate of VvSTS, VvCHS decreased during the berry development. Our study demonstrates that water stress regulates resveratrol synthesis through enzymatic activities and the gene expression of PAL and STS.

Functional phenotypic plasticity mediated by water stress and [CO2] explains differences in drought tolerance of two phylogenetically close conifers.

Forests are threatened globally by increased recurrence and intensity of hot droughts. Functionally close coexisting species may exhibit differences in drought vulnerability large enough to cause niche differentiation and affect forest dynamics. The effect of rising atmospheric [CO2], which could partly alleviate the negative effects of drought, may also differ between species. We analysed functional plasticity in seedlings of two taxonomically close pine species (Pinus pinaster Ait., Pinus pinea L.) under different [CO2] and water stress levels. The multidimensional functional trait variability was more influenced by water stress (preferentially xylem traits) and [CO2] (mostly leaf traits) than by differences between species. However, we observed differences between species in the strategies followed to coordinate their hydraulic and structural traits under stress. Leaf 13C discrimination decreased with water stress and increased under elevated [CO2]. Under water stress both species increased their sapwood area to leaf area ratios, tracheid density and xylem cavitation, whereas they reduced tracheid lumen area and xylem conductivity. Pinus pinea was more anisohydric than P. pinaster. Pinus pinaster produced larger conduits under well-watered conditions than P. pinea. Pinus pinea was more tolerant to water stress and more resistant to xylem cavitation under low water potentials. The higher xylem plasticity in P. pinea, particularly in tracheid lumen area, expressed a higher capacity of acclimation to water stress than P. pinaster. In contrast, P. pinaster coped with water stress comparatively more by increasing plasticity of leaf hydraulic traits. Despite the small differences observed in the functional response to water stress and drought tolerance between species, these interspecific differences agreed with ongoing substitution of P. pinaster by P. pinea in forests where both species co-occur. Increased [CO2] had little effect on the species-specific relative performance. Thus, a competitive advantage under moderate water stress of P. pinea compared with P. pinaster is expected to continue in the future.

Assessing Grapevine Water Status by Integrating Vine Transpiration, Leaf Gas Exchanges, Chlorophyll Fluorescence and Sap Flow Measurements

A precise knowledge of the grapevine responses to increasing level of water stress is of the utmost relevance for an effective application of deficit irrigation strategies in viticulture. Against this background, a study was conducted on potted grapevines subjected to two ten-day drought cycles to assess their water status by integrating the information derived from different physiological indexes including whole-plant transpiration (measured gravimetrically and with sap flow sensors), leaf gas exchanges and chlorophyll fluorescence. When soil water availability was not limited, vine transpiration rate was determined mainly by environmental factors and ranged between 0.5 and 2 L day−1 m−2 of leaf surface. Transpiration was affected by the soil water availability only when water stress became evident (midday stem water potential < −1 MPa), with vines showing a strong limitation of the stomata functioning (stomatal conductance < 0.05 mol m−2 s−1) and, consequently, low transpiration rates (<0.5 L m−2 d−1). Transpiration rates measured with the sap flow sensors were correlated with those measured gravimetrically, showing daily patterns that were highly affected by the intensity of the water stress. Nevertheless, these sensors highly underestimated actual transpiration rates, limiting their reliability for vineyard irrigation management. At the end of the second drought cycle, vines showed very limited responses to daily changes in environmental conditions (same photosynthetic rate and stomatal conductance at morning, midday and afternoon), likely reflecting a carryover stress effect from the first drought cycle and an incomplete physiological recovery before the beginning of the second. Evidence of the severe water stress reached by vines was also given by the high value of the quantum yield of nonregulated energy dissipation (Y(NO) higher than 0.4) found at the end of the first drought cycle. Taken together, the obtained results integrate the current knowledge on water stress development in grapevine, also highlighting the relevance of specific physiological indexes that could be used effectively for the correct management of deficit strategies in viticulture.

De novo transcriptome assembly from the nodal root growth zone of hydrated and water-deficit stressed maize inbred line FR697

Certain cultivars of maize show increased tolerance to water deficit conditions by maintenance of root growth. To better understand the molecular mechanisms related to this adaptation, nodal root growth zone samples were collected from the reference inbred line B73 and inbred line FR697, which exhibits a relatively greater ability to maintain root elongation under water deficits. Plants were grown under various water stress levels in both field and controlled environment settings. FR697-specific RNA-Seq datasets were generated and used for a de novo transcriptome assembly to characterize any genotype-specific genetic features. The assembly was aided by an Iso-Seq library of transcripts generated from various FR697 plant tissue samples. The Necklace pipeline was used to combine a Trinity de novo assembly along with a reference guided assembly and the Viridiplantae proteome to generate an annotated consensus “SuperTranscriptome” assembly of 47,915 transcripts with a N50 of 3152 bp in length. The results were compared by Blastn to maize reference genes, a Benchmarking Universal Single-Copy Orthologs (BUSCO) genome completeness report and compared with three maize reference genomes. The resultant ‘SuperTranscriptome’ was demonstrated to be of high-quality and will serve as an important reference for analysis of the maize nodal root transcriptomic response to environmental perturbations.