Bimetallic Single‑Atom Catalysts for Water Splitting

Green hydrogen from water splitting has emerged as a critical energy vector with the potential to spearhead the global transition to a fossil fuel-independent society.The field of catalysis has been revolutionized by single-atom catalysts(SACs),which exhibit unique and intricate interactions between atomically dispersed metal atoms and their supports.Recently,bimetallic SACs(bimSACs)have garnered significant attention for leveraging the synergistic functions of two metal ions coordinated on appropriately designed supports.BimSACs offer an avenue for rich metal–metal and metal–support cooperativity,potentially addressing current limitations of SACs in effectively furnishing transformations which involve synchronous proton–electron exchanges,substrate activation with reversible redox cycles,simultaneous multi-electron transfer,regulation of spin states,tuning of electronic properties,and cyclic transition states with low activation energies.This review aims to encapsulate the growing advancements in bimSACs,with an emphasis on their pivotal role in hydrogen generation via water splitting.We subsequently delve into advanced experimental methodologies for the elaborate characterization of SACs,elucidate their electronic properties,and discuss their local coordination environment.Overall,we present comprehensive discussion on the deployment of bimSACs in both hydrogen evolution reaction and oxygen evolution reaction,the two half-reactions of the water electrolysis process.

Influence of Water Stress on the Physiological and Biochemical Characteristics of Scutellaria Baicalensis Georgi

Previous studies have shown that water stress can stimulate biosynthesis of secondary metabolites,and physiological and biochemical characteristics of plant can play a key role in its defense responses to water stress.So the physiological and biochemical characteristics of potted Scutellaria baicalensis Georgi plants were investigated under continuous water stress condition.The results showed that the water content in roots,stems and leaves,together with chlorophyll content of the leaves decreased as the water stress strengthened.Simultaneously,the specific leaf weight increased,and the content of proline and soluble sugar in Scutellaria baicalensis Georgi leaves increased significantly.The changing trends of the baicalin content in the roots,stems and leaves of Scutellaria baicalensis Georgi were different.It increased continuously in roots,while ascended constantly in the stems and leaves during the early days under the water stress,but decreased sharply under the heavy stress.In conclusion,proline and soluble sugar had a close correlation with the drought resistance of Scutellaria baicalensis Georgi.Moderate drought is in favor of synthesizing the secondary metabolites.

Effects of Different Water Stresses on Eco-physiological Characteristics of Hippophae rhamnoides Seedlings

In order to examine the effects of the decrease of future precipitation on the eco-physiological characteristics of sea buckthorn (Hippophae rhamnoides Linn.) in Huangfuchuan Watershed in Nei Mongol, a water gradient experiment was conducted based on the four specially designed water supply levels, including normal precipitation, slight drought, drought and extreme drought. Results of ANOVE showed that different water gradients had a significant effect on (1) microhabitat factors, such as soil water content and soil temperature; (2) gas exchange, such as net photosynthetic rate, stomatal conductance and transpiration rate; (3) resource use efficiency; and (4) leaf water potential. Water use efficiency of H rhamnoides could increase under moderate water stress, i.e. drought condition, while its net photosynthetic rate and transpiration rate decreased. All kinds of eco-physiological characteristics proved H. rhamnoides seedlings under all water supplies were affected by water stress more or less and that mechanism of intrinsic physiological regulation in seedlings under the extreme drought conditions had the appearance of turbulence to a certain extent. Therefore, H rhamnoides seedlings in Huangfuchuan Watershed could not acclimate to extreme drought conditions.

Study on the Changes of Physiological Indexes of Water Spinach in Eutrophication Water

[Objective] Effect of hypoxic water culture on physiological characteristic of water spinach and its hypoxia tolerance were studied.[Method] Water spinach was planted in soil and eutrophication water by means of floating bed,respectively,and the change of physiological indexes including chlorophyll,proline（Pro）,malondialdehyde（MDA）,soluble sugar and soluble protein in water spinach leaves at mature stage was researched,while the hypoxia tolerance of water spinach and the effect of plant density on water spinach growth were discussed in our paper.[Result] In the hypoxic eutrophication water,the content of total chlorophyll,malondialdehyde,soluble sugar and soluble protein in water spinach leaves was lower than that of soil culture,with higher proline content,which showed that water spinach had better tolerance to hypoxic eutrophication water;the higher the plant density,the lower the chlorophyll content in water spinach leaves,and there was no significant effect of plant density on proline and malondialdehyde content,while soluble protein content was higher under high plant density.[Conclusion] The best plant density of water spinach was 66 plants per floating bed with the area of 2 m2,which could provide theoretical basis for the application of water spinach in floating bed.

Preliminary Study on Water Physiological Characters of Male and Female Ginkgo biloba L.

[Objective] The experiment aimed to study the difference of water physiology of male and female Ginkgo biloba L. for discussing the strategy of water utilization as well as the important role of this difference during evolution process. [Method] The stem sap flow, stomatal conductance(Gs), transpiration rate(Tr) and water use efficiency (WUE) of male and female Ginkgo biloba L. were comparatively studied. [Result] The day-night processes of flow on male and female Ginkgo biloba L. were similar. The flow on male and female Ginkgo biloba L. in day were almost same while the flow at night on male Ginkgo biloba L. was bigger than that on female Ginkgo biloba L. The Tr and Gs of male and female Ginkgo biloba L. were high in morning and at night but low at noon ,while Tr and Gs of female Ginkgo biloba L. in morning and at night were higher than these of male Ginkgo biloba L. at the same time point. However, these indexes of female plant were lower than these of male plant from 11:00 to 14:00. WUE changing trends of male and female Ginkgo biloba L. were similar, while average water utilization rate of female Ginkgo biloba L. was slightly lower than that of male Ginkgo biloba L. [Conclusion] Compared with other companion plants, water physiology of male and female Ginkgo biloba L. had strong homoplasy. The phenomenon might be a survival strategy of dioecious plants under long term evolutionary pressure.

Effect of Water Control before Transplanting and Rooting Powder Treatment on Tobacco Seedling Quality and Physiological Properties at Green Stage

Cultivating strong seedlings is an important guarantee for the production of high-quality flue-cured tobacco, while there are many disadvantages in tobacco floating system that is commonly adopted in China. To improve the tobacco floating system, with Xiangyan No.3 as experimental material, the effects of water control before transplanting and rooting powder treatment on tobacco seedling quality and physiological properties at green stage were investigated. The results showed that： （1） water control showed small influence on tobacco seedling quality, while rooting powder treatment and water control ＋ rooting powder treatment showed great influence on tobacco seedling quality, mainly represented by reduced plant height, thickened stem and increased dry matter accumulative amount; （2） water control before transplanting and rooting powder treatment all improved leaf chlorophyll content and root vigor of tobacco seedlings, and the effect of water control ＋ rooting powder treatment was best, followed by rooting powder treatment and water control; （3） all treatments increased the nitrate reductase and invertase activity, and reduced the MDA content of tobacco seedlings, and the effect of water control ＋ rooting powder treatment was best, followed by rooting powder treatment and water control. Mean- while, the treatment effect 10 d before the transplanting was better than that 5 d before the transplanting. In overall, the improvement effects of water control 10 d before transplanting ＋ rooting powder treatment on tobacco seedling quality and physiological properties at green stage were the best.

Effects of Waterlogging Stress on Growth and Physiological Index in Cucumber Seedlings

The effects of waterlogging stress on the growth, chlorophyll and MDA content of cucumber seedlings were studied by using cucumber varieties （Cucumis sativus L. cv. Jinyan No.7） as materials. The results show that plant height, leaf number, shoot fresh weight, total root length, total projected area and total surface area of cucumber seedlings showed insignificant differences with those of the control; root fresh weight, root average diameter, total root volume were significantly higher, but the number of root tips and furcation number increased first and then reduced; the chlorophyll content of cucumber seedlings was significantly lower than that of control; MDA content was significantly higher than that of control under waterlogging stress. It was showed that the cucumber was tolerant to waterlogging stress, but the ability of waterlogging stress was limited, and the physiological was significantly hurt and photosynthesis of cucumber seedlings was significantly affected by waterlogging stress.

Effects of Water Stress on Some Physiological Characteristics and Yield Compensation of Rice in Booting Stage

[Objective] The physiological characteristics and yield compensation effects of rice in booting stage were studied after water recovery when rice suffered water stress to provide references for improving rice water utilization efficiency and its drought resistance. [Method] The pot experiments with five rice varieties under three different treatments of water stresses were conducted to study physical signs every six days after water water-recovery. [Result] Along with the increase of water recov- ery, leaf water potential, SPAD and Pn values in treatment B （light drought） in- creased fast, and its compensation effect of the soluble sugar content was higher than that of treatment C （severe drought）; all sap flow speeds in treatments with water stresses fell. As for yield components, panicles per plant and spikelets per panicle decreased with water stress degree, and the decline of spikelets per pani- cle, in particular, was greatly influenced by water stress. Seed setting percentages in treatment B most reached peaks of different varieties, except of D you No. 363. The thousand-seed weight and ear weight per plant in treatment B and C both dropped, compared with control group. [Conclusion] When regular management was resumed after rice underwent water stress at booting stage, many characteristics and yield traits of rice got favorable compensation effects in the light water-stress treatments.

Effects of Different Irrigation Amounts on Physiological Indexes and Water Use Efficiency of Rice at the Jointing-booting Stage

[Objective] This study was conducted to investigate the effects of different irrigation amounts on rice leaf physiology and water use efficiency. [Method] The irrigation test with three different treatments was carried out in the Agrometeo- rological Experimental Station of Nanjing University of Information Science ＆ Technology. [Reset] Under flood irrigation, the rice leaf temperature was lower than wet irrigation by 0.4-0.7 ℃; when the strength of photosynthetically active radiation was in the range of 800-1 800 gmol/（m^2·s）, the average stomatal conductance of rice leaves under flood irrigation was higher than that of the wet irrigation treatment by 0.123-0.183 mol H2O/（m^2·s）, and the leaf water use efficiency was higher than that of the wet irrigation treatment by 0.24 g/kg; after 10：00 every day, the water use efficiency under flood irrigation was always higher than that of the wet irrigation treatment; and compared with the wet irrigation treatment, the rice of the flood irrigation treatments had higher leaf water use efficiency, and final yields were also remarkably improved by 5.89%-13.97%. [Conclusion] This study will provide a practical reference basis for field management.

Effect of continuous negative pressure water supply on the growth, development and physiological mechanism of Capsicum annuum L.

Effects of continuous negative pressure water supply on water consumption, growth and development, as well as physiological mechanism and quality of Capsicum annuum L. were investigated in this paper. Meanwhile, the optimal negative pressure water supply conditions for growth of C. annuum L. were screened out to achieve the goals of water conservation, high yield and high quality, thus providing theoretical foundation for its field production. The pot experiment within the greenhouse was utilized; the continuous negative pressure water supply was adopted; the four treatments, artificial watering（CK）, –5 k Pa（T1）, –10 k Pa（T2）, and –15 k Pa（T3） were set; and the daily water consumption, yield, as well as the biomass, nitrate reductase, root activity, vitamin C, capsaicin, and nutrient uptakes of nitrogen（N）, phosphorus（P） and potassium（K） during various stages of its growth were determined. Compared with CK, when the water supply pressure was controlled at –5 to –15 k Pa in the experiment, the total water consumption of C. annuum L. reduced by 53.42 to 67.75%, the total water consumption intensity reduced by 54.29 to 67.14%, and the water use efficiency increased by 12.66 to 124.67%. The N accumulation in a single strain of C. annuum L. from the color turning stage to the red ripe stage increased by 15.99 to 100.55%, respectively, compared with that of CK; the P accumulation increased by 20.47 to 154.00% relative to that of CK, and the K accumulation increased by 64.92 to 144.9% compared with that of CK. Compared with CK, C. annuum L. yield was remarkably improved by 13.79% at T1, and contents of vitamin C, capsaicin as well as carotenoids at all growth stages were enhanced by 13.42–147.01%, 11.54–71.01%, and 41.1–568.06%, respectively. Nitrate reductase activity, root activity and chlorophyll（a＋b） were markedly increased by 335.78–500%, 79.6–140.68% and 114.95–676.19%, respectively, from immature stage to full ripe stage. Adopting the continuous negative pressure water supply for C. annuum L. has a significant water-saving effect, and the water supply pressure being stable at –5 k Pa contributes to its growth and development, improves yield, enhances root activity, promotes nutrient uptake, and improves its quality, thus achieving the effects of water conservation, high yield, high quality and high efficiency.

Growth and Eco-Physiological Performance of Cotton Under Water Stress Conditions

A cotton cultivar Xinluzao 8 was grown under four levels of water stress treatments （normal irrigation, slight, mild and severe water stress） from the initial reproductive growth stage in Shihezi, Xinjiang, China, in 2002, to evaluate the growth and eco-physiological performances. Under water stress conditions, the transpiration ability decreased while the leaf temperature increased. Although the relative leaf water content decreased as water stress increased, the differences among the treatments were small, indicating that cotton has high ability in maintaining water in leaf. The stomatal density increased as water stress increased, while the maximum stomatal aperture reduced only in the severest stressed plants. The time of the maximum stomatal aperture was delayed in the mild and severe stressed plants. When severe stress occurred, the stomata were kept open until the transpiration decreased to nearly zero, suggesting that the stomata might not be the main factor in adjusting transpiration in cotton. Cotton plant has high adaptation ability to water stress conditions because of decrease in both stomatal conductance and hydraulic conductance from soil-to-leaf pathway. The actual quantum yield of photosystem Ⅱ （PS Ⅱ） decreased under water stress conditions, while the maximum quantum yield of PS Ⅱ did not vary among treatments, suggesting that PS II would not be damaged by water stress. The total dry weight reduced as water stress increased.

The Relative Contribution of Non-Foliar Organs of Cotton to Yield and Related Physiological Characteristics Under Water Defi cit

Water deficit is one of the most important causes of decreased yield in cultivated plants. Non-foliar green organs in cotton play an important role in yield formation at the late growth stage. Although better photosynthetic performance was observed in a non-foliar organ （bract） compared with leaves under water deficit. However, the physiological response of each organ in cotton to water deficit has not been comprehensively studied in relation to the water status and photosynthesis characteristics. We studied the maintenance of water status of each organ in cotton by measuring their relative water content, proline content and stomatal characteristics. Water deficit significantly decreased the surface area of each organ, but to a lesser extent in non-foliar organs. Our results showed that the relative contribution of biomass accumulation of non-foliar organs increased under water deficit. Non-foliar organs （bracts and capsule wall） showed less ontogenetic decrease in O2 evolution capacity and in RuBPC activity （per dry weight） as well as better antioxidant systems than leaves at various days after anthesis. We conclude that the photosynthesis from non-foliar organs is important for increasing cotton yield especially under water deficit conditions.

Physiological evaluation of nitrogen use efficiency of different apple cultivars under various nitrogen and water supply conditions

Nitrogen(N) deficiency is a common problem for apple(Malus×domestica) production in arid regions of China.However,N utilization efficiency(NUE) of different apple cultivars grown under low N conditions in arid regions has not been evaluated.In this study,NUE was assessed for one-year-old seedlings of six apple cultivars,Golden Delicious,Qinguan,Jonagold,Honeycrisp,Fuji and Pink Lady,grafted onto Malus hupehensis Rehd.rootstocks.Four treatments were used,including control water with control N(CWCN),limited water with control N(LWCN),control water with low N(CWLN) and limited water with low N(LWLN).Our results showed that growth indices such as biomass,plant height and stem diameter,and photosynthetic rate of all cultivars decreased in the order CWCN>CWLN>LWCN>LWLN.When subjected to LWLN treatment,Qinguan showed better growth and photosynthetic characters than other tested cultivars.Additionally,Qinguan and Pink Lady had higher NUE,while Honeycrisp and Jonagold had lower NUE,based on the determination of biomass,photosynthetic parameters,chlorophyll content,the maximal photochemical efficiency of PSII(Fv/Fm),15 N and N contents.

Evaluation of photosynthesis, physiological, and biochemical responses of chickpea (Cicer arietinum L. cv. Pirouz) under water deficit stress and use of vermicompost fertilizer

One goal in the face of drought stress conditions is to increase growth and yield through the reduction of negative effects of stress. Vermicompost can play an effective role in plant growth and development and in reducing harmful effects of various environmental stresses on plants due to its porous structure, high water storage capacity, having hormone-like substances, plant growth regulators, and high levels of macro and micro nutrients. This study considered the physiological, biochemical, and photosynthetic responses of the chickpea to different combinations of vermicompost and water stress in a greenhouse environment. Two factors were involved, addition of vermicompost to soil at four ratios： control （100 wt% （weight percentage） sol0; 10 wt% vermicompost＋90% soil; 20 wt% vermicompost＋80 wt% soil; 30 wt% vermicompost＋70 wt% soil weight percentage, and treatment of water stress at three levels including 75, 50, and 25% of field capacity. The results showed that vermicompost had a significant effect on all traits under stress and non-stress conditions. Application of vermicompost in soil, especially at the levels of 20 and 30 wt% significantly increased all studied traits under non-stress conditions. Under moderate stress conditions, vermicompost at 30 wt% treatment resulted in a significant increase in the photosynthetic pigments, CO2 assimilation rate, internal leaf CO2 concentration, transpiration, the maximal quantum yield of photosystem II （PSII） photochemistry （FJF）, concentrations of Ca and K in root and leaf tissues, proline and soluble protein contents in root tissues. Peroxidase （POX） and catalase （CAT） enzyme activities decreased significantly with increasing proportions of vermicompost, but the activity of superoxide dismutase was not significantly different. In conclusion, the above results showed that vermicompost fertilizer had a positive effect on physiological, biochemical, and photosynthetic responses of chickpea under non-stress and moderate stress conditions, but no positive effect was determined under severe water stress.

Effect of different water supply on morphology, growth and physiological characteristics of Salix psammophila seedlings in Maowusu sandland, China

Response pattern was investigated for seedlings of Salix psammophila, a dominant shrub in Maowusu sandland, to the simulated precipitation change by artificially controlling water supply at four levels. The growth characters, in terms of plant height, stem diameter, total branch number, total leaf number and area, total bifurcation ratio, total branch lenght and branch number, branch lenght, leaf number and leaf area of each branch order, and leaf, branch and root biomass significantly increased when water supply increased. That water supply had significant effect on biomass allocation showed different investment pattern of biomass resource of the seedlings grown under different water supply treatments. Stomatal density of abaxial leaf surface decreased, and stomatal apparatus length and width of adaxial and abaxial leaf surface increased with the increase of water supply, while Stomatal density of adaxial leaf surface was not affected by water supply. Water supply obviously affected the diumal changes of photosynthetic rate, and the photosynthetic rate of the seedlings showed strongly midday depression grown under the 157.5 mm water supply, but not grown under higher water supply. Additionally the assimilation-light response curves and flourescence efficiency more showed that water supply improve photosynthesis capacity. Finally, S. psammophila seedlings stood out by their slow growth and relatively high investments in root growth in order to reduce tissue losing rate and consumption of water resource for keeping water balance under water stress. The seedlings that grown under rich water supply did by their fast growth and relatively high investments in branch and leaf growth in order to improve the power of capturing light energy for higher photosynthesis.

Some Physiological Processes Related to Water Use Efficiency of Higher Plants

Water use efficiency （WUE） of higher plants is of vital importance in the dry-land agricultural ecosystem in terms of the development of water-saving agriculture. Of all the approaches used to improve WUE, the intrinsic water use efficiency （WUET, the ratio of CO2 assimilation rate to transpiration rate） can be a right index, as the variation of WUET is correlated with the physiological and biochemical processes of higher plants. The measurements of leaf gas exchange and carbon isotope discrimination （D^13C） are the two ways to detect the variation in WUEr. This article reviewed some physiological processes related to WUEv, including the relationship between CO2 assimilation and stomatal conductance and WUET and water absorption. The relationship between WUE and aquaporin and the yield are discussed as well.

Physiological performance of three calcifying green macroalgae Halimeda species in response to altered seawater temperatures

The effects of seawater temperature on the physiological performance of three Halimeda species were studied for a period of 28 d.Five treatments were established for Halimeda cylindracea,Halimeda opuntia and Halimeda lacunalis,in triplicate aquaria representing a factorial temperature with 24°C,28°C,32°C,34°C and 36°C,respectively.The average Fv/Fm of these species ranged from 0.732 to 0.756 between 24°C and 32°C but declined sharply between 34°C(0.457±0.035)and 36°C(0.122±0.014).Calcification was highest at 28°C,with net calcification rates(Gnet)of(20.082±2.482)mg/(g·d),(12.825±1.623)mg/(g·d)and(6.411±1.029)mg/(g·d)for H.cylindracea,H.opuntia and H.lacunalis,respectively.Between 24°C and 32°C,the specific growth rate(SGR)of H.lacunalis(0.079%–0.110%d–1)was lower than that of H.cylindracea(0.652%–1.644%d–1)and H.opuntia(0.360%–1.527%d–1).Three Halimeda species gradually bleached at 36°C during the study period.Malondialdehyde(MDA)and proline levels in tissues of the three Halimeda were higher in 34–36°C than those in 24–32°C.The results indicate that seawater temperature with range of 24–32°C could benefit the growth and calcification of these Halimeda species,however,extreme temperatures above 34°C have negative impacts.The measured physiological parameters also revealed that H.cylindracea and H.opuntia displayed broader temperature tolerance than H.lacunalis.

Quantifying Responses of Winter Wheat Physiological Processes to Soil Water Stress for Use in Growth Simulation Modeling

A deep understanding of crop-water eco-physiological relations is the basis for quantifying plant physiological responses to soil water stress. Pot experiments were conducted to investigate the winter wheat crop-water relations under both drought and waterlogging conditions in two sequential growing seasons from 2000 to 2002, and then the data were used to develop and validate models simulating the responses of winter wheat growth to drought and waterlogging stress. The experiment consisted of four treatments, waterlogging (keep 1 to 2 cm water layer depth above soil surface), control (70%-80% field capacity), light drought (40%-50% field capacity) and severe drought (30%-40% field capacity) with six replicates at five stages in the 2000-2001 growth season. Three soil water content treatments (waterlogging, control and drought) with two replicates were designed in the 2001-2002 growth season. Waterlogging and control treatments are the same as in the 2000-2001 growth season. For the drought treatment, no water was supplied and the soil moisture decreased from field capacity to wilting point. Leaf net photosynthetic rate, transpiration rate, predawn leaf water potential, soil water potential, soil water content and dry matter weight of individual organs were measured. Based on crop-water eco-physiological relations, drought and waterlogging stress factors for winter wheat growth simulation model were put forward. Drought stress factors integrated soil water availability, the sensitivity of different development stages and the difference between physiological processes (such as photosynthesis, transpiration and partitioning). The quantification of waterlogging stress factor considered different crop species, soil water status, waterlogging days and sensitivity at different growth stages. Data sets from the pot experiments revealed favorable performance reliability for the simulation sub-models with the drought and waterlogging stress factors.

Growth and Physiological Performance of Aerobic and Lowland Rice as Affected by Water Stress at Selected Growth Stages

Aerobic rice technology is still new in Malaysia, and information regarding MARDI Aerob 1(MA1), the first local aerobic rice variety, is still lacking. Therefore, comparative studies were carried out to determine the physiological performance of aerobic rice variety MA1 and lowland rice variety MR253 under water stress given at the panicle initiation, flowering and ripening stages. This experiment was arranged in a randomized complete block design. Stomatal conductance(g_s), chlorophyll a fluorescence(F_v/F_m), leaf relative water content(leaf RWC), and soil moisture content(SMC) as well as yield component parameters such as panicle number, grain yield and 100-grain weight were measured. Results revealed that gs and leaf RWC for both varieties decreased with depletion of SMC. The correlation study between the physiological parameters and SMC indicated that F_v/F_m was not affected by water stress, regardless of varieties. The yield components(panicle number, grain yield and 100-grain weight) for both varieties greatly decreased when water stress was imposed at the panicle initiation stage. This study showed that the panicle initiation period was the most sensitive stage to water stress that contributed to a substantial reduction in yield for both varieties. Under the aerobic condition(control), MR253 produced higher panicle number, 100-grain weight and yield than MA1. Although MR253 is bred for lowland, it is well adapted to aerobic condition.

Physiological and Biochemical Basis of Water-Deficit Stress Tolerance in Pearl Millet Hybrid and Parents

The present investigation was aimed to understand the physiological and biochemical basis of water-deficit stress tolerance in pearl millet [Pennisetum glaucum (L.) R. Br.] hybrid ICMH 356 and its parents ICMR 356 (♂) and ICMB 88004 (♀) in response to and recovery from drought stress and also to comprehend crop adaptation under dryland conditions. A field experiment was conducted in a split plot design with moisture levels as the main plot and genotypes as the sub plots. A comparative analysis of hybrid and parents under well-watered and water-deficit stress conditions revealed that the hybrid was superior over the parents in terms of leaf water relations, excised leaf water retention capacity, accumulation of compatible solutes, photosynthesis, membrane stability index and antioxidative enzyme viz., superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (APX) and guaiacol peroxidase (GPOX) activities. ANOVA for these parameters was also found to be significant for genotypes, treatments and their interactions at 0.01% level. Maintenance of superiority in terms of these physiological and biochemical parameters coupled with better recovery ability upon stress relief are crucial physiological mechanisms contributing to water deficit stress tolerance in pearl millet. Simple correlation coefficient analysis revealed significant positive association of yield at 0.01% level with relative water content, leaf water potential, stomatal conductance, photosynthesis, proline, total soluble sugars, free amino acids, membrane stability index, leaf area index and total biomass, while a significant negative association with solute potential and malondialdehyde content, under water-deficit stress clearly indicated that such relationships can be positively attributed to drought tolerance.