Transcriptomic and metabolomic analysis of changes in grain weight potential induced by water stress in wheat

The sink strength of developing ovaries in wheat determines the grain weight potential.The period from booting to the grain setting stage is critical for ovary growth and development and potential sink capacity determination.However,the underlying regulatory mechanism during this period by which the wheat plant balances and coordinates the floret number and ovary/grain weight under water stress has not been clarified.Therefore,we designed two irrigation treatments of W0(no seasonal irrigation)and W1(additional 75 mm of irrigation at the jointing stage)and analyzed the responses of the ovary/grain weight to water stress at the phenotypic,metabolomic,and transcriptomic levels.The results showed that the W0 irrigation treatment reduced the soil water content,plant height,and green area of the flag leaf,thus reducing grain number,especially for the inferior grains.However,it improved the grain weight of the superior and inferior grains as well as average grain weight at maturity,while the average ovary/grain weight and volume during–3 to 10 days after anthesis(DAA)also increased.Transcriptomic analysis indicated that the genes involved in both sucrose metabolism and phytohormone signal transduction were prominently accelerated by the W0 treatment,accompanied by greater enzymatic activities of soluble acid invertase(SAI)and sucrose synthase(Sus)and elevated abscisic acid(ABA)and indole-3-acetic acid(IAA)levels.Thus,the sucrose content decreased,while the glucose and fructose contents increased.In addition,several TaTPP genes(especially TaTPP-6)were down-regulated and the IAA biosynthesis genes TaTAR1 and TaTAR2 were up-regulated under the W0 treatment before anthesis,which further increased the IAA level.Collectively,water stress reduced the growth of vegetative organs and eliminated most of the inferior grains,but increased the ABA and IAA levels of the surviving ovaries/grains,promoting the enzymatic activity of Sus and degrading sucrose into glucose and fructose.As a result,the strong sucrose utilization ability,the enhanced enzymatic activity of SAI and the ABA-and IAA-mediated signaling jointly increased the weight and volume of the surviving ovaries/grains,and ultimately achieved the tradeoff between ovary/grain weight and number in wheat under water stress.

Effects of nitrogen deposition on the carbon budget and water stress in Central Asia under climate change

Atmospheric deposition of nitrogen(N)plays a significant role in shaping the structure and functioning of various terrestrial ecosystems worldwide.However,the magnitude of N deposition on grassland ecosystems in Central Asia still remains highly uncertain.In this study,a multi-data approach was adopted to analyze the distribution and amplitude of N deposition effects in Central Asia from 1979 to 2014 using a process-based denitrification decomposition(DNDC)model.Results showed that total vegetation carbon(C)in Central Asia was 0.35(±0.09)Pg C/a and the averaged water stress index(WSI)was 0.20(±0.02)for the whole area.Increasing N deposition led to an increase in the vegetation C of 65.56(±83.03)Tg C and slightly decreased water stress in Central Asia.Findings of this study will expand both our understanding and predictive capacity of C characteristics under future increases in N deposition,and also serve as a valuable reference for decision-making regarding water resources management and climate change mitigation in arid and semi-arid areas globally.

Enhancing Canola Yield and Photosynthesis under Water Stress with Hydrogel Polymers

While Egypt’s canola production per unit area has recently grown,productivity remains low,necessitating increased productivity.Hydrogels are water-absorbent polymer compounds that can optimize irrigation schedules by increasing the soil’s ability to retain water.Accordingly,twofield experiments were conducted to examine hydrogel application to sandy soil on canola growth,biochemical aspects,yield,yield traits,and nutritional quality of yielded seeds grown under water deficit stress conditions.The experiments were conducted by arranging a split-plot layout in a randomized complete block design(RCBD)with three times replications of each treatment.While water stress at 75%or 50%of crop evapotranspiration(ETc)lowered chlorophyll a,chlorophyll b,caro-tenoids,and total pigments content,indole-3-acetic acid,plant development,seed yield,and oil and total carbo-hydrates of seed yield,hydrogel treatment enhanced all of the traits mentioned above.Furthermore,hydrogel enhanced to gather compatible solutes(proline,amino acids,total soluble sugars),phenolics content in leaves,seed protein,and crop water productivity,which increased while the plants were under water stress.The results revealed that the full irrigation(100%ETc)along with hydrogel compared to water-stressed(50%ETc)led to enhanced seed yield(kg ha^(-1)),Oil(%),and Total carbohydrates(%)of rapeseed by 57.1%,11.1%and 15.7%,respectively.Likewise,under water-stressed plots with hydrogel exhibited enhancement by 10.0%,3.2%and 5.1%in seed yield(kg ha^(-1)),oil(%),and total carbohydrates(%)of rapeseed by 57.1%,11.1%and 15.7%,respec-tively compared to control.As a result,the use of hydrogel polymer will be a viable and practical solution for increasing agricultural output under water deficit stress situations.

Hydrogen-rich water alleviates constipation by attenuating oxidative stress through the sirtuin1/nuclear factor-erythroid-2-related factor 2/heme oxygenase-1 signaling pathway

BACKGROUND Constipation,a highly prevalent functional gastrointestinal disorder,induces a significant burden on the quality of patients'life and is associated with substantial healthcare expenditures.Therefore,identifying efficient therapeutic modalities for constipation is of paramount importance.Oxidative stress is a pivotal contributor to colonic dysmotility and is the underlying pathology responsible for constipation symptoms.Consequently,we postulate that hydrogen therapy,an emerging and promising intervention,can serve as a safe and efficacious treatment for constipation.AIM To determine whether hydrogen-rich water(HRW)alleviates constipation and its potential mechanism.METHODS Constipation models were established by orally loperamide to Sprague-Dawley rats.Rats freely consumed HRW,and were recorded their 24 h total stool weight,fecal water content,and charcoal propulsion rate.Fecal samples were subjected to 16S rDNA gene sequencing.Serum non-targeted metabolomic analysis,malondialdehyde,and superoxide dismutase levels were determined.Colonic tissues were stained with hematoxylin and eosin,Alcian blue-periodic acid-Schiff,reactive oxygen species(ROS)immunofluorescence,and immunohistochemistry for cell growth factor receptor kit(c-kit),PGP 9.5,sirtuin1(SIRT1),nuclear factor-erythroid-2-related factor 2(Nrf2),and heme oxygenase-1(HO-1).Quantitative real-time PCR and western blot analysis were conducted to determine the expression level of SIRT1,Nrf2 and HO-1.A rescue experiment was conducted by intraperitoneally injecting the SIRT1 inhibitor,EX527,into constipated rats.NCM460 cells were induced with H2O2 and treated with the metabolites to evaluate ROS and SIRT1 expression.RESULTS HRW alleviated constipation symptoms by improving the total amount of stool over 24 h,fecal water content,charcoal propulsion rate,thickness of the intestinal mucus layer,c-kit expression,and the number of intestinal neurons.HRW modulated intestinal microbiota imbalance and abnormalities in serum metabolism.HRW could also reduce intestinal oxidative stress through the SIRT1/Nrf2/HO-1 signaling pathway.This regulatory effect on oxidative stress was confirmed via an intraperitoneal injection of a SIRT1 inhibitor to constipated rats.The serum metabolites,β-leucine(β-Leu)and traumatic acid,were also found to attenuate H2O2-induced oxidative stress in NCM460 cells by up-regulating SIRT1.CONCLUSION HRW attenuates constipation-associated intestinal oxidative stress via SIRT1/Nrf2/HO-1 signaling pathway,modulating gut microbiota and serum metabolites.β-Leu and traumatic acid are potential metabolites that upregulate SIRT1 expression and reduce oxidative stress.

Research Progress on Economic Forest Water Stress Based on Bibliometrics and Knowledge Graph

This study employed the bibliometric software CiteSpace 6.1.R6 to analyze the correlation between thermal infrared,spectral remote sensing technology,and the estimation of economic forest water stress.It aimed to review the development and current status of this field,as well as to identify future research trends.A search was conducted on the China National Knowledge Infrastructure(CNKI)database using the keyword“water stress”for relevant studies from 2003 to 2023.The visual analysis function of CNKI was used to generate the distribution of annual publication volume,and CiteSpace 6.1.R6 was utilized to create network maps illustrating collaboration among authors and institutions.The study also analyzed the hotspots and frontiers of economic forest water stress.As a result,a total of 6664 academic journal articles related to water stress were retrieved.Considerable collaboration networks were observed among scholars and institutions,with a focus on using crown temperature monitoring to diagnose crop water stress.Based on the research findings,it was evident that the primary research trend involved the use of thermal infrared and spectral remote sensing technology for estimating water stress,making it a future research hotspot.

The influences of canopy temperature measuring on the derived crop water stress index

Crop water stress index(CWSI)is widely used for efficient irrigation management.Precise canopy temperature(T_(c))measurement is necessary to derive a reliable CWSI.The objective of this research was to investigate the influences of atmospheric conditions,settled height,view angle of infrared thermography,and investigating time of temperature measuring on the performance of the CWSI.Three irrigation treatments were used to create different soil water conditions during the 2020-2021 and 2021-2022 winter wheat-growing seasons.The CWSI was calculated using the CWSI-E(an empirical approach)and CWSI-T(a theoretical approach)based on the T_(c).Weather conditions were recorded continuously throughout the experimental period.The results showed that atmospheric conditions influenced the estimation of the CWSI;when the vapor pressure deficit(VPD)was>2000 Pa,the estimated CWSI was related to soil water conditions.The height of the installed infrared thermograph influenced the T_(c)values,and the differences among the T_(c)values measured at height of 3,5,and 10 m was smaller in the afternoon than in the morning.However,the lens of the thermometer facing south recorded a higher T_(c)than those facing east or north,especially at a low height,indicating that the direction of the thermometer had a significant influence on T_(c).There was a large variation in CWSI derived at different times of the day,and the midday measurements(12:00-15:00)were the most reliable for estimating CWSI.Negative linear relationships were found between the transpiration rate and CWSI-E(R^(2)of 0.3646-0.5725)and CWSI-T(R^(2)of 0.5407-0.7213).The relations between fraction of available soil water(FASW)with CWSI-T was higher than that with CWSI-E,indicating CWSI-T was more accurate for predicting crop water status.In addition,The R^(2)between CWSI-T and FASW at 14:00 was higher than that at other times,indicating that 14:00 was the optimal time for using the CWSI for crop water status monitoring.Relative higher yield of winter wheat was obtained with average seasonal values of CWSI-E and CWSI-T around 0.23 and 0.25-0.26,respectively.The CWSI-E values were more easily influenced by meteorological factors and the timing of the measurements,and using the theoretical approach to derive the CWSI was recommended for precise irrigation water management.

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.

Effects of Water Stress on Photosynthesis and Fluorescence Characteristics in Peony

[ Objective] Study on the photosynthesis and fluorescence characteristics in peony under water stress. [ Method ] The two peony varieties Huhong and Luoyanghong were treated by different water stress for determining the photosynthesis and fluorescence characteristics. [ Result ] With the aggravation of water stress, the net photosynthetic rate （Pn） and stomatal conductance （Gs） decreased, while the intercellular CO2 concentration （Ci） increased. Drought could decrease Pn, constrain gas exchange and change the daily photosynthesis. Fo of peony leaf increased and Fv/Fm decreased under water stress especially water logging, causing the inactivation of the PS II reaction center, and the chlorophyll fluorescence characters gradually recovered until afternoon. [ Conclusion] The 75% soil relative water content （SRWC） is the best condition for growth of peony. Compared with drought, water logging is more unfit for the growth of peony. For the two varieties, Huhong assumed more tolerance to drought, accordingly more adaptability.

Signal Transduction from Water Stress Perception to ABA Accumulation

To cope with unpredictably environmental perturbations and sometimes stresses, plants have evolved with some mechanisms so that these developing stresses can be sensitively perceived and the physiology can be rapidly regulated. Such perception and regulation can be a kind of feed_forward mechanism and may involve many biochemical and physiological processes and/or the expression of many genes. Although many dehydration_responsive genes have been identified, much fewer of their functions have been known. Such stress_ induced responses should include the initial perception of the dehydration signal, then the complicated signal transduction and cellular transmission until to the final gene activation or expression. As an important plant stress hormone abscisic acid (ABA) mediates many such responses. We believe that starting from the initial perception of dehydration to the gene expression leading to the stress_induced ABA biosynthesis is the most important stress signal transduction pathway among all the plant responses to stresses. Identification of the genes involved and understanding their roles during stress perception and physiological regulation shall be the most important and interesting research field in the coming years.

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 water stress on Haloxylon ammodendron seedlings in the desert region of Heihe inland river watershed, Gansu Province, China

The water relation and leaf gas exchange of saxoul (Haloxylon Ammodendron Bge, a C4 shrub) seedlings were studied under water stress in 2001. Saxoul seedlings maintained high transpiration when the soil moisture was above 11%. The seedlings were able to take up water from soil with above 6 % soil water content, which was the threshold level of soil moisture for seedlings. The relationship between transpiration and potential evaporation was linear for well-watered seedlings. The de-crease of soil water availability led to different degrees of down-regulation of stomatal conductance, leaf transpiration and net CO2 assimilation rate. The stomata played a relatively small part in determining the net CO2 assimilation rate for the same seedling. The relationship between net CO2 assimilation rate and transpiration was linear diurnally, and reduction scale of leaf transpiration was much bigger than that of net CO2 assimilation rate by waters tress treatments, therefore intrinsic wa-ter-use-efficiency increased. High evaporative demand increased the leaf transpiration but inhibited net CO2 assimilation rate. Because of the effect of VPD on transpiration in this region, the transpiration of well-watered and mild water stress seedlings becomes responsive to change in stomatal conductance over a wider range.

Effects of Water Stress on Leaf Water and Chlorophyll Fluorescence Parameters of Sugarcane Seedling

[Objective] The aim was to explore the effects of water stress on leaf water and chlorophyll fluorescence parameters of sugarcane seedling,as well as to provide basis for the study on sugarcane production and evaluation. [Method] Seven different sugarcane varieties were studied at the seedling stage under drought stress,and the changes of leaf water and chlorophyll fluorescence parameters under stress conditions were detected. [Result] leaf water potential,leaf relative water content and soil relative water content showed a certain amount of internal relationship,the sugarcane varieties that had more tolerant to drought had higher utilization rate of soil water; the correlation analysis and factor analysis suggested that the survival rate at seedling stage under drought stress,Fv/Fm,leaf water potential and relative water content could be used as drought resistance evaluation indicators. [Conclusion] As a relatively independent influencing factor,water potential had dominating effect on drought resistance,and the reliability of Fv/Fm as drought resistance evaluation indicator had been verified.

ACC and MACC Biosynthesis and Ethylene Production in Water-Stressed Spring Wheat

Changes of ACC and MACC levels, ACC synthase activity as well as ethylene production in the leaves of two spring wheat (Triticum aestivum L.) cultivars 8139 (with relatively low drought-resistance) and 504 (with relatively high drought-resistance) during water stress were determined. The levels of ACC and MACC in both cultivars decreased in the first 24 It of water stress and increased in the second 24 It while the activities of ACC synthase increased continuously throughout the entire period of treatment (48 h), As water stress progressed, ethylene production decreased continuously in cv. 8139 but remarkably increased earlier and decreased later in the cv. 504. Moreover, the decrease in RWC of stressed leaves was greater and the changes in ACC and MACC levels as well as ACC synthase activity were higher in the drought-sensitive cv. 8139 than in the drought-resistant cv, 504 during water stress. The levels of ACC and MACC, activities of ACC synthase and productions of ethylene in the stressed leaves in two cultivars were significantly altered by the application of MGBG (an inhibitor of SAMDC) and AOA (an inhibitor of ACC synthase) where their effects on these items were almost opposite. They were increased by the former inhibitor but reduced by the latter. All of these results suggested that the level of ethylene production in plants did not depend on the level of ACC during water stress. The increase in the level of ethylene in the drought-resistant cultivar during the earlier period of water stress might be a phenomenon of adaptation to water stress and be correlated with the development of the drought-tolerance in plants and playing role in the transduction of stress signal. The role of MACC, however, was primarily in the regulation of ethylene production under water stress.

Responses of the seedlings of five dominant tree species in Changbai Mountain to soil water stress

Soil water stress was studied on the potted seedlings of five dominant tree species (Pinus koraienes Sieb.et Zucc., Fraxinus mandshurica Rupr., Juglans mandshurica Maxim, Tilia amurensis Rupr. and Quercus mongolica Fisch.ex Turcz) from the broadleaved/Korean pine forest in Changbai Mountain. Leaf growth, water transpiration and photosynthesis were compared for each species under three soil moisture conditions: 85%-100% (high water, CK), 65%-85% (Medium water, MW) and 45%-65% (low water, LW) of 37.4% water-holding capacity in field. The results showed that the characteristic of typical drought-resistance of the leaves is significantly developed. The net photosynthetic rate and water use efficiency of Fraxinus mandshurica were higher in MW than those in CK. But for the other four species, the net photosynthetic rate and water use efficiency in CK were lower than those in MW and LW. The transpiration rate responding to soil moistures varied from species to species.

Variable chlorophyll fluorescence in response to water plus heat stress treatments in three coniferous tree seedlings

Effects of water and heat stress treatments on chlorophyll fluorescence of Chinese fir (Cunninghamia lanceolata), Masson pine (Pinus massoniana) and western redcedar (Thuja plicata D. Don)_seedlings were monitored during a three-cycle stress period. It was shown that ratio of variable to maximal chlorophyll fluorescence (Fv/Fm) of these three species responded differently to water stress treatments. The Fv/Fm ratio of western redcedar decreased dramatically after water stress, while that of Chinese fir had only a slight reduction and that of Masson pine had no significant change. The experiment also showed that the Fv/Fm ratio of all three species differed significantly under heat stress treatments. Concerning three different water plus heat stress cycles, it was found that the Fv/Fm ratios of Chinese fir and Masson pine measured at the end of each water plus heat stress cycle were not significantly different. However, the Fv/Fm ratio of western redcedar was diminished significantly in response to an increase of stress time. Keywords Chinese fir - Chlorophyll fluorescence - Heat stress - Masson pine - Water stress - Western redcedar CLC number Q945.17 - S791.248 Document code A Biography: Yu Fang-yuan (1965-), male, Ph. Doctor. Associate professor in College of Forest Resources and Environment, Nanjing, Forestry University, Nanjing 210037, P. R. China.Responsible editor: Zhu Hong

Responses of Apple Rootstock Leaf Structure on Water Stress

[Objective] The aim was to explore, leaf structure characters of Malus rockii and Malus robusta at drought and rewatedng. [Method] The research used Malus rockii and Malus robusta as test materials to conduct water stress treatment by water control and rewatering. [Result] Malus rockii consists of two layers of pal- isade tissue and Malus robusta consist of three layers of columnar cells. Leaf of Malus robusta is thicker, and the thickness of leaf palisade tissue-to-the thickness of spongy tissue ratio is higher. In contrast, leaf stoma of Malus rockii performs more sensitively to water change, and the stoma area after rewatering is 10 times as high as Malus robusta. Besides, after rewatering, SR grows higher, the thickness of leaf palisade tissue-to-the thickness of spongy tissue ratio declines of the two test materials, but the changes of Malus robusta prove more significant. [Conclusion] The two test materials are different in responses to drought and rewatering, and the leaf structure characters of Malus robusta changes obviously than that of Malus rockii during water variation in terms of resisting drought.

DNA Damage and Repair of Two Ecotypes of Phragmites communis Subjected to Water Stress

In order to thoroughly understand the mechanism Of drought resistance in plants at DNA level, the DNA damage of two ecotypes of reeds (Phragmites communis T.) stressed by PEG 6000 was analyzed by means of fluorescence analysis of DNA unwinding (FADU). The results showed that the residual double strand DNA percentages (dsDNA%) in dune reed (DR) were significantly higher than those in swamp reed (SR) treated with either 20% or 30% PEG 6000. This meant that the DNA of DR was less damaged in comparison with SR. Similarly, DR resisted DNA damage more strongly than SR as reactive oxygen species (ROS) increased by adding ROS producers diethyldithio carbamate (DDC), H2O2 and Fe2+ of different concentrations. Meanwhile, treating PEG stressed SR with ROS scavengers such as dimethyl sulphoxide (DMSO) and ascorbic acid (Vc) resulted in the reduction of DNA damage, suggesting that ROS could cause DNA damage. In addition, the DNA repair for water-stressed reeds indicated that DR repaired DNA damage much faster and more completely. This might be the first indication that drought stress led to DNA damage in plants and that drought resistance of plants was closely related to DNA damage and repair.

Effects of Water Stress on Stay Green of Sugarcane Innovative Materials Yunge F_2 Generation

[Objective] This study aimed to investigate the effect of water stress on stay green of Yunge F2 generation. [Method] Total 26 sugarcane innovative germplasm materials of Yunge F2 generation, along with their female parent, were selected as the experimental materials. Based on the observation on appearance of stray green and other five physiological and biochemical indexes, the drought resis- tance of the experimental materials was evaluated comprehensively by subordinate function method, grey relational analysis, and cluster analysis. [Result] The rank of drought resistance of the experimental materials was not exactly the same between subordinate function method and grey relational analysis. However, the drought .re- sistance evaluation results by isometric range-based cluster analysis were consistent with those by the two foregoing methods except Yunge F2 11-68 and Yunge F1 11- 254. At the Euclidean distance of 2.00, the tested materials were classified into four groups. The first group included 8 drought-strongly resistant materials, the third group included 6 drought-moderately resistant materials, the fourth group included 3 drought-poorly resistant materials, and the second group included drought-strongly resistant and drought-moderately resistant materials. The drought resistance coeffi- cients of green leaf numberLtotal leaf number and top four leaves chlorophyll content showed significantly positive correlation with drought resistance comprehensive eval- uation value, thus green leaf number/total leaf number and top four leaves chloro- phyll content could be used as the evaluation indexes of drought resistance in sug- arcane. [Conclusion] The excellent materials possess strong drought resistance and good green holding performance, such as Yunge F2 11-159, can be used as crucial parents and basic germplasm materials in drought resistance breeding of sugarcane. 7

Studies on the Secretion of Organic Acids from Roots of Two-year-old Larix olgensis under Nutrient and Water Stress

[Objective] This study aimed to investigate the effects of nutrient and water stress on the secretion of organic acids from roots of two-year-old Larix olgensis. [Method] Different nutrient and water stress conditions were designed to investi- gate the types and quantities of organic acids secreted from roots of two-year-old L. olgensis. [Result] Under nutrient and water stress, the types of organic acids secreted from roots of two-year-old L. olgensis increased, which varied with different stress levels. In addition, nutrient and water stress also increased the secretory vol- ume of organic acids from roots of two-year-old L. olgensis. The increment in total amount of organic acids reached the maximum under Level 1 （high stress）. Among different types of organic acids, the increment in secretory volume of citric acid reached the maximum, followed by malic acid, while oxalic acid presented relatively small increment. Furthermore, the increment in secretory volume of these three organic acids all reached the maximum under Level 1. [Conclusion] The proportion of the secretory volume of each organic acid accounting for the total amount of organic acids varied slightly, but the overall order was unchanged.

Effects of Water Stress on Economic Characters of Water-saving Rice Variety Luhan No.1

[Objective] This study aimed at exploring the utilization rate of water of the new water-saving rice variety ＂Luhan No.1＂ and providing references and basis for the further demonstration and extension.[Method] Water-saving rice variety ＂Luhan No.1＂ and original receptor ＂6527＂ were used for dry processing without aquifer,and rice under regular irrigation conditions was used as the control.[Result] Under conditions which had economized on 67.4% of water compared with the regular irrigation,decreasing rates of 1 000-seed weight,seed setting rate,plant height and effective panicles of ＂Luhan No.1＂ were relatively small and had not achieved a significant level,while the decreasing rates of production of the region,total grains per panicle,theoretical production and filled grains per panicle of the original receptor ＂6527＂ were all over 25% and had attained very significant levels（P0.01）.[Conclusion] ＂Luhan No.1＂ had shown stable production,energy conservation,reducing environmental pollution and other advantages under water-conservating cultivation conditions.