Proteome analysis of alfalfa roots in response to water deficit stress

To evaluate the response of alfalfa to water deficit （WD） stress, WD-induced candidates were investigated through a proteomic approach. Alfalfa seedlings were exposed to WD stress for 12 and 15 days respectively, followed by 3 days re-watering. Water deficit increased H202 content, lipid peroxidation, DPPH （1,1-diphenyl-2-picrylhydrazyl）-radical scavenging activity, and the free proline level in alfalfa roots. Root proteins were extracted and separated by two-dimentional polyacrylamide gel electrophoresis （2-DE）. A total of 49 WD-responsive proteins were identified in alfalfa roots; 25 proteins were reproducibly found to be up-regulated and 24 were down-regulated. Two proteins, namely cytosolic ascorbate peroxidase （APx2） and putative F-box protein were newly detected on 2-DE maps of WD-treated plants. We identified several proteins including agamous-like 65, albumin b-32, inward rectifying potassium channel, and auxin-independent growth promoter. The identified proteins are involved in a variety of cellular functions including calcium signaling, abacisic acid （ABA） biosynthesis, reactive oxygen species （ROS） regulation, transcription/translation, antioxidant/detoxification/stress defense, energy metabolism, signal transduction, and storage. These results indicate the potential candidates were responsible for adaptive response in alfalfa roots.

Endogenous Levels of Polyamines under Water-Deficit Stress during Cotton’s Reproductive Development

Polyamines, putrescine (PUT), spermidine (SPD) and spermine (SPM) are implicated in plants’ responses under conditions of abiotic stress. Previous research in other crops has indicated that polyamines and changes in their concentrations are associated with drought tolerance under conditions of water-deficit stress;however, no information exists on cotton (Gossypium hirsutum L.). Growth chamber experiments were conducted with two cotton cultivars differing in drought tolerance, ST5288B2F (drought-sensitive) and Siokra L23 (drought-tolerant) in order to investigate the distribution of free polyamines, the effect of water-deficit stress on the polyamine metabolism of cotton reproductive units and their subtending leaves as well as the possible relationship between polyamines and drought tolerance in cotton. Our results showed that cotton ovaries contained significantly higher levels of total free polyamines compared to their subtending leaves under both control and water stress conditions. Water-deficit stress significantly increased PUT concentrations in ST5288B2F, while SPM levels significantly decreased in Siokra L23. The results indicated that water-deficit stress significantly affected cotton polyamine metabolism in reproductive structures and their subtending leaves;however, no clear relationship between drought-tolerance and changes in polyamine accumulation was established. Further research is needed to elucidate the mechanism according to which water-deficit stress affects polyamine metabolism.

Effect of 1-MCP on Gas Exchange and Carbohydrate Concentrations of the Cotton Flower and Subtending Leaf under Water-Deficit Stress

Ethylene is an endogenous plant hormone that increases under adverse environmental conditions, resulting in leaf and fruit abscission and ultimately yield reduction. In cotton, however, the effects of water-deficit stress on ethylene production have been uncertain. In this study it was hypothesized that application of an ethylene inhibitor 1-Methylcyclo- propene (1-MCP) would prevent ethylene production and result in alleviation of water-deficit stress consequences on the physiology and metabolism of the cotton flower and subtending leaf. To test this hypothesis, growth chamber experiments were conducted in 2009-2010 with treatments consisting of (C) untreated well-watered control, (C + 1MCP) well-watered plus 1-MCP, (WS) untreated water-stressed control, and (WS + 1MCP) water-stressed plus 1-MCP. The plants were subjected to two consecutive drying cycles during flowering, approximately 8 weeks after planting, and 1-MCP was foliar applied at a rate of 10g. ai/ha at the beginning of each drying cycle. The results showed that 1-MCP application had no significant effect on gas exchange functions and did not prevent reductions from water stress in leaf photosynthesis, respiration and stomatal conductance. However, application of 1-MCP resulted in a decrease in sucrose content of water-stressed pistils compared to the control indicating that 1-MCP has the potential to interfere in carbohydrate metabolism of reproductive units.

Adaptability and recovery capability of two maize inbred-line foundation genotypes, following treatment with progressive water-deficit stress and stress recovery

Two maize inbred lines, the foundation genotype Y478 and its derived line Z58, are widely used to breed novel maize cultivars in China, but little is known about which traits confer Z58 with superior drought tolerance and yield. In the present study, responses in growth traits, photosynthetic parameters, chlorophyll fluorescence and leaf micromorphological characteristics were evaluated in Y478 and Z58 subjected to water-deficit stress induced by PEG 6000. The derived line Z58 showed greater drought tolerance than Y478, which was associated with higher leaf relative water content (RWC), root efficiency, and strong growth recovery. Z58 showed a higher stomatal density and stomatal area under the non-stressed condition;in these traits, both genotypes showed a similar decreasing trend with increased severity of water-deficit stress. In addition, the stomatal size of Y478 declined significantly. These micromorphological differences between the two lines were consistent with changes in physiological parameters, which may contribute to the enhanced capability for growth recovery in Z58. A non-linear response of Fv/Fm to leaf RWC was observed, and Fv/Fm decreased rapidly with a further gradual decline of leaf RWC. The relationship between other chlorophyll fluorescence parameters (photochemical quenching and electron transport rate) and RWC is also discussed.

Polyamine Metabolism of the Cotton Flower and Its Sub-tending Leaf under Water-Deficit Stress in the Field

Polyamines, putrescine, spermidine and spermine are low molecular weight polycations implicated in flowering and seed set and plants’ responses under adverse environmental conditions. Research in other crops has shown that polyamine metabolism is greatly affected by water-deficit stress, however, no information exists on cotton (Gossypium hirsutum L.). A field study was conducted in 2011 in two contrasting locations (Fayetteville, AR, and Lubbock, TX) in order to investigate the effect of water-deficit stress during flowering on polyamine metabolism of the cotton flower and its subtending leaf. Treatments consisted of control (well watered) and water-stress (irrigation withheld for two weeks at the onset of flowering) in a split plot design. First day white flowers and their subtending leaves were collected at the end of each week of the stress period for determination of polyamine concentrations. Water-deficit stress resulted in significant increases in PUT and SPD levels of pistils and leaves compared to the control. However, pistil and leaf SPM content significantly increased under drought conditions in one location and remained unaltered in the other one. Leaf and pistil polyamine metabolism of cotton appeared to be greatly affected by limited water supply, however further research is needed to elucidate the ways polyamines can be used to increase cotton drought tolerance.

Physiological Mechanism of Nitrogen Mediating Cotton (<i>Gossypium hirsutum</i>L.) Seedlings Growth under Water-Stress Conditions

The objective of this investigation was to study the effects of nitrogen on tolerance to water-stress in cotton (Gossypium hirsutum L.) seedlings. Growth chamber studies with pots of washed sand were carried out in Fayetteville, USA, and Nanjing, Chinawith three water conditions (well-watered, drought-stressed, and waterlogging), and three nitrogen rates, low nitrogen (16 mM, approximately 224 mg N·l–1 water), medium nitrogen (24 mM, approximately 448 mg N·l–1 water) and high nitrogen (32 mM, approximately 672 mg N·l–1 water), respectively. The results showed that water-stress treatments reduced plant biomass, C/N ratio, root vigor and leaf photosynthesis (Pn). The plant response to water-stress resistance was affected by nitrogen, and was correlated with the activities of antioxidant enzymes. The changes of anti-oxidant enzymes was the highest in the low nitrogen rate in the drought-stressed and waterlogged cotton seedlings. Malondialdehyde (MDA) content increased significantly in the water-stress treatments, and was the lowest in the low nitrogen rate. There was a significant reduction of N accumulation under water stress. Low-nitrogen treatmentincreased C accumulation, while high-nitrogen treatment decreased N accumulation. Root vigor was decreased by water stress, and was highest in the low-nitrogen rate. After terminating the water stress, N application promoted root vigor, especially in waterlogged seedlings. The trends of Pn weresimilarto that of root vigor. These results suggested that low N application may contribute to cotton drought tolerance by enhancing the activity of antioxidant enzymes and conse-quently decreasing lipid peroxidation, and enhancing root vigor. However, higher N should be applied to waterlog- ging-stressed cotton seedlings after terminating waterlogging.

Quantifying the impacts of soil water stress on the winter wheat growth in an arid region,Xinjiang

Wheat growth in response to soil water deficit play an important role in yield stability. A field experiment was conducted for winter wheat (Triticum aestivum L.) during the period of 2002-2005 to evaluate the effects of limited irrigation on winter wheat growth. 80%, 70%, 60%, 50% and 40% of field capacity was applied at different stages of crop growth. Photosynthetic characteristics of winter wheat, such as photosynthesis rate, transpiration rate, stomatal conductance, photosynthetically active radiation, and soil water content, root and shoot dry mass accumulation were measured, and the root water uptake and water balance in different layer were calculated. Based on the theory of unsaturated dynamic, a one-dimensional numerical model was developed to simulate the effect of soil water movement on winter wheat growth using Hydrus-1 D. The soil water content of stratified soil in the experimental plot was calculated under deficit irrigation. The results showed that, in different growing periods, evapotranspiration, grain yield, biomass, root water uptake, water use efficiency, and photosynthetic characteristics depended on the controlled ranges of soil water content. Grain yield response to irrigation varied considerably due to differences in soil moisture contents and irrigation scheduling between seasons. Evapotranspiration was largest in the high soil moisture treatment, and so was the biomass, but this treatment did not produce the highest grain yield and root water uptake was relatively low. Maximum depth of root water uptake is from the upper 80 cm in soil profile in jointing stage and dropped rapidly upper 40 cm after heading stage, and the velocity of root water uptake in latter stage was less than that in middle stage. The effect of limited irrigation treatment on photosynthesis was complex owing to microclimate. But root water uptake increased linearly with harvest yield and improvement in the latter gave better root water uptake under limited irrigation conditions. Appropriately controlled soil water contents can improve the root water uptake and grain yield. Consistently high values of root water uptake and grain yield were produced under conditions of mild water deficit at the seedling and start of regrowth to stem-elongation stages, in addition to a further soil water depletion at the physiological maturity to harvest stage. We suggest that periods of mild soil water depletion in the early vegetative growth period together with severe soil water depletion in the maturity stage of winter wheat is an optimum for limited irrigation regime in this oasis. Considerable potential for further improvement in agricultural water use efficiency in the arid zone depends on effective conservation of moisture and efficient use of the limited water.

Cold water swimming pretreatment reduces cognitive deficits in a rat model of traumatic brain injury

A moderate stress such as cold water swimming can raise the tolerance of the body to potentially injurious events. However, little is known about the mechanism of beneficial effects induced by moderate stress. In this study, we used a classic rat model of traumatic brain injury to test the hypothesis that cold water swimming preconditioning improved the recovery of cognitive functions and explored the mechanisms. Results showed that after traumatic brain injury, pre-conditioned rats（cold water swimming for 3 minutes at 4℃） spent a significantly higher percent of times in the goal quadrant of cold water swim, and escape latencies were shorter than for non-pretreated rats. The number of circulating endothelial progenitor cells was significantly higher in pre-conditioned rats than those without pretreatment at 0, 3, 6 and 24 hours after traumatic brain injury. Immunohistochemical staining and Von Willebrand factor staining demonstrated that the number of CD34~＋ stem cells and new blood vessels in the injured hippocampus tissue increased significantly in pre-conditioned rats. These data suggest that pretreatment with cold water swimming could promote the proliferation of endothelial progenitor cells and angiogenesis in the peripheral blood and hippocampus. It also ameliorated cognitive deficits caused by experimental traumatic brain injury.

蘸水处理对月季切花保鲜效果的影响

为分析蘸水处理对月季切花的保鲜效果,以‘卡罗拉’月季切花为试材,分别进行蘸水处理和不蘸水处理,于4℃下贮藏,并测定其腐烂指数、萎蔫指数、花朵直径、失重率、呼吸强度、丙二醛(MDA)含量。冷藏试验结果表明,蘸水处理能够降低鲜切花在冷藏过程中膜脂过氧化产物MDA含量和鲜切花呼吸代谢的速率,从而延缓衰老,延长鲜切花的贮藏时间。瓶插试验结果表明,蘸水处理在冷藏15 d后瓶插期间最大花径达6.90 cm,大于不蘸水处理组的6.09 cm,蘸水处理可有效延缓鲜切花腐烂指数、萎蔫指数和失重率的上升,抑制月季切花贮藏和瓶插期间品质的下降。综上,蘸水处理对月季切花具有较好的保鲜效果。本研究结果可为延长‘卡罗拉’月季切花的瓶插寿命及保鲜剂研究提供理论依据。

水分亏缺胁迫对马铃薯块茎产量构成的影响

为了探究水分亏缺胁迫对马铃薯块茎产量构成的影响,以马铃薯品系BFL10和BFL12为试验材料,对不同水分胁迫状态下马铃薯各生育期的株高、分枝数、匍匐茎数量、单株结薯数量和单株结薯重量进行测定。结果表明:水分亏缺胁迫对马铃薯株高和分枝数的影响因品种熟性而异;重度水分亏缺胁迫显著降低了两个品系的单株结薯数量、单株大薯数量和单株结薯重量,轻度水分亏缺胁迫显著降低了单株大薯数量,推测轻度水分亏缺可能通过影响薯块膨大降低产量,而重度水分亏缺是通过影响薯块膨大和减少薯块数量两个方面降低产量。

Exogenous abscisic acid coordinating leaf senescence and transport of assimilates into wheat grains under drought stress by regulating hormones homeostasis

Drought at the grain filling stage of wheat will cause premature leaf senescence, thus leading to considerable loss of wheat yield. Therefore, this paper aims to establish a cultivation technology for strong drought resistance, delayed senescence, and yield improvement based on the analysis of hormones homeostasis obtained by applying chemical control substances. Experiments were conducted with two genotypes of wheat. Four water irrigation treatments were applied to impose the water deficit, including well-watered control treatment(WW), mild water deficit(MiWD), moderate water deficit(MoWD), and severe water deficit(SWD). Exogenous abscisic acid(ABA) was sprayed on the plants at the anthesis stage of the wheat. As a result, exogenous ABA reduced initial senescence rate(r0), total duration of chlorophyll(Chltotal), rapid senescence phase(Chlloss), and the accumulated temperature at an inflection point(M) but improved the persistence phase(Chlper) of flag leaves under all of the four treatments. However, exogenous ABA produced inconsistent effects on photoassimilate relocation and grain weight under different treatments. It produced positive regulatory effects on grain weight under WW, MiWD, and MoWD treatments. On the one hand, spraying ABA during the persistence phase of flag leaves reduced the ratios of zeatin to gibberellin(Z/GA3), spermine to spermidine(Spm/Spd), and salicylic acid to ABA(SA/ABA),which prolonged active photosynthesis by stimulating high level of proline(Pro) and increased the activities of antioxidant enzymes, such as superoxide dismutase(SOD), peroxidase(POD), catalase(CAT), and ascorbate peroxidase(APX). Therefore, drought tolerance was enhanced, and more photosynthetic assimilates were accumulated. On the other hand, the rapid senescence phase and the transport rate of assimilates into grains were accelerated, resulting in higher grain weight, yield, and water use efficiency(WUE). However, under SWD treatment, exogenous ABA improved the ratio of SA/ABA, leading to low Pro content and low antioxidant enzyme activity of flag leaves in the rapid loss phase. Meanwhile,drought resistance declined and the transport duration of assimilates into grains was shortened, thus making photosynthetic assimilates redundant. Therefore, exogenous ABA can lead to the reduction in grain weight, yield, and WUE of wheat under SWD treatment.

马铃薯水分胁迫指数模型优化研究

【目的】探究马铃薯的叶气温差与环境因子的关系,进一步优化马铃薯水分胁迫指数模型。【方法】在河南农业大学林学院试验基地进行马铃薯盆栽试验,选择晴朗天气测定不同土壤含水率下马铃薯的叶气温差随太阳辐射和大气饱和水汽压差(VPD)的变化规律,确定作物水分胁迫指数(crop water stress index,CWSI)的上下基线,进一步试验后得到优化后的马铃薯CWSI经验模型,并对相关模型进行验证。【结果】马铃薯的叶气温差随着土壤含水率的降低而升高;当土壤含水率较低(7.28%)时,马铃薯的叶气温差随太阳辐射的增大而增大,呈显著线性关系;当土壤含水率较高(15.85%)时,马铃薯的叶气温差随VPD的增大而减小,呈显著线性关系;构建出马铃薯CWSI的上基线为y=0.0098Q-0.68[Q为太阳辐射强度/(W·m^(-2))],下基线为y=-1.67V+3.75(V为大气饱和水汽压差/kPa);将优化的CWSI模型验证后得知,随着土壤含水率的减少,CWSI值增加,且CWSI同土壤含水量呈极显著负相关关系(p<0.01)。【结论】马铃薯的最大叶气温差与太阳辐射的线性关系作为马铃薯水分胁迫指数的上基线是可行的,该研究对传统CWSI经验模型进行改进,进一步优化了CWSI经验模型。

亏缺灌溉条件下增施硅肥对番茄生长发育及品质的影响研究

为有效提高番茄种植水肥利用效率,促进作物生长,提升番茄产量及品质,以番茄为研究对象,设置3个灌溉水量(100%Ep、75%Ep和50%Ep,Ep为作物蒸发蒸腾量,分别用W100、W75和W50表示)和3个硅肥施加量(0、1、2 mmol/L,分别用Si0、Si1和Si2表示)共9组处理,分析亏缺灌溉条件下增施硅肥对番茄生长发育、产量及品质的影响。结果表明,W75Si1、W100Si2、W75Si2处理的株高、茎粗和叶片干物质量最大,生长发育最佳,产量最高,株高、茎粗、叶片干物质量和产量均随着灌溉水量和施硅量的增加而增加,且灌溉水量和施硅量及其交互作用对株高、茎粗、叶片干物质量、水分利用效率(WUE)及产量影响显著(P<0.05),水分利用效率随着硅肥的增加和灌溉水量的降低而增加;番茄红素、可溶性糖和可溶性固形物均随灌溉水量的增加呈现出上升趋势,维生素C随硅肥的增加呈现出现先增加后下降趋势;施硅处理在促进番茄生长发育、提高产量和促进番茄红素合成的同时,也抑制了维生素C、可溶性糖和可溶性固形物含量的形成。隶属函数法表明,W75Si2处理能够提高水分利用效率,促进番茄生长,提升产量及品质,是试验条件下最优的灌溉方式。

华北平原40年夏玉米作物系数变化及影响因素

作物系数(作物实际蒸散量与参考作物蒸散量之比,Kc)作为农田需耗水确定的关键参数,对农业精准灌溉和节水具有重要的参考价值。研究作物系数如何受生产条件和气象条件变化的影响,可为准确确定作物系数提供依据。本研究基于中国科学院栾城农业生态系统试验站1980—2018年充分灌溉条件下夏玉米作物系数变化规律及影响因素,利用2019—2021年夏玉米不同灌水处理下的试验数据,确定不同供水条件下夏玉米作物系数的计算方法。结果表明,1980—2018年参考作物蒸散量(ETo)基本保持稳定,但存在年际波动。充分供水条件下夏玉米实际蒸散量(ETc)在2005年之前保持年际间稳定,近年来年际间波动幅度较大。作物实际蒸散量与参考作物蒸散量之比的作物系数多年平均值为0.91,年际变异系数为12.36%。作物系数受作物产量和大气条件影响,产量的增加伴随着夏玉米实际蒸散量的增加,参考作物蒸散量主要受平均风速和日照时数的影响。分析表明作物系数由参考作物蒸散量和实际蒸散量共同决定,且受夏玉米实际蒸散量的影响较大。灌水量的差异是造成相同年份不同处理间差异的主要因素。利用缺水处理下土壤水分状况和不同土层相对根长密度计算土壤水分胁迫系数,结果表明使用缺水灌溉处理的土壤有效水分含量对夏玉米作物系数进行校正,所得值与实际值最为接近,可根据计划控制的土壤水分状况调整作物系数,确定不同控水条件下的农田实际耗水量。

淮北地区干旱胁迫对冬小麦不同土壤中生长及水分利用效率影响与差异性分析

为探究不同干旱胁迫在各生育期中对冬小麦在砂姜黑土和黄潮土中生长发育的影响与差异,基于2022年五道沟水文实验站桶栽干旱试验,在冬小麦返青-拔节、拔节-抽穗、抽穗-乳熟期进行水分控制,设置轻旱、中旱、重旱3个胁迫水平及全生育期无旱对照(CK),分析各生育阶段不同干旱胁迫对冬小麦在砂姜黑土和黄潮土中株高、耗水量、产量、水分利用效率(WUE)的影响与差异。结果表明:①两种土壤冬小麦各生育阶段受旱影响下,株高小于对照组,重旱对株高的抑制最显著,拔节-抽穗期受旱对株高造成持续抑制影响;收获时黄潮土各处理株高均低于砂姜黑土,但干旱影响下,黄潮土各生育阶段受旱组株高抑制水平均小于砂姜黑土。②两种土壤各生育阶段耗水量随干旱加重而减少,重旱减少趋势最显著,且耗水量减少均会使总耗水量低于对照组,但黄潮土各受旱组基于对照减少水平均小于砂姜黑土。③两种土壤随干旱加重减产加剧,砂姜黑土各处理组产量均大于黄潮土,但黄潮土返青-拔节期、拔节-抽穗期相比砂姜黑土有一定抗旱能力;抽穗-乳熟期,砂姜黑土抗旱能力优于黄潮土。④各处理砂姜黑土WUE均高于黄潮土,抽穗-乳熟期差距最显著,该生育阶段受旱对黄潮土冬小麦的影响比砂姜黑土更大。

干旱胁迫和复水对火麻生理及次生代谢产物含量的影响

为探究火麻干旱胁迫的耐受能力及复水后其次生代谢产物的含量变化。以土培盆栽的方式培养火麻幼苗,以正常浇水的火麻为对照(CK),对比分析胁迫组在胁迫后的0、3、5、7、9 d和复水后的生理特性、光合及次生代谢产物的变化情况。结果表明:干旱胁迫条件下,火麻叶中含水量、光合指标、最大光能转换效率、实际光能转换效率、电子传递速率RET、光化学淬灭系数Qp降低;而非光化学淬灭系数QNP、叶绿素和类胡萝卜素、脯氨酸、可溶性蛋白、可溶性糖及MDA含量和相对电导率上升,4种抗氧化酶活性升高,复水后叶片含水量、叶绿素b、光合指标、脯氨酸含量和SOD活性低于CK组,其他各生理指标均高于CK组水平。总黄酮、总酚和总萜含量升高,复水后这3种次生代谢产物含量不同程度地低于对照。火麻的第1、2对叶片中CBD含量随胁迫程度的增加而降低,且远高于下部叶片;第3、4对叶中CBD含量虽在7 d胁迫处理时含量最高,但仍低于对照并且2者差异不显著(P<0.05);第5、6对叶片在胁迫处理的3 d时CBD含量达到峰值。复水后,3组叶位中的CBD含量均高于CK组。综合研究发现,适度的干旱胁迫会提高火麻的生理抗逆性,降低其光合作用,提高次生代谢产物的含量;胁迫会降低药物活性物质CBD的含量;在适度的胁迫经复水后,缓解了胁迫对植物的伤害,并提高叶片中CBD的含量。

不同干旱胁迫及亚精胺复水对南方红豆杉生理特性的影响

为了解干旱胁迫以及复水喷施亚精胺对南方红豆杉(Taxus chinensis var.mairei)生理特性的影响,采用盆栽控水法模拟不同干旱环境,设置正常供水(CK)、轻度干旱(T1)、中度干旱(T2)、重度干旱(T3)4个处理,并施加3种浓度外源亚精胺复水处理(N1、N2、N3),探究不同干旱条件下南方红豆杉的抗旱机理,对比出最佳的外源亚精胺复水浓度。结果表明:干旱胁迫在短期内可显著提高南方红豆杉叶片的叶绿素总含量、SOD活性以及可溶性蛋白含量,并显著增加丙二醛(MDA)的累积(P<0.05),且随胁迫时间的延长呈不同的波动变化,在重度干旱胁迫下,其各项数值的变化幅度更大,SOD活性、可溶性蛋白含量的峰值来临时间越早。复水试验中,喷施3种浓度的亚精胺相比单一复水处理(EGCK)均有显著的促进作用(P<0.05),其中对幼苗期南方红豆杉复水+1.0mmol/L外源亚精胺的组合效果(N2)最好,且3种亚精胺浓度对南方红豆杉的干旱恢复作用表现为:N2>N3>N1。综合研究认为,适度的干旱胁迫导致生理代谢活动双向波动,将干旱胁迫锻炼和喷施亚精胺结合,可提高南方红豆杉的农艺性状,增强植株的抗逆性。

短期干旱对水稻叶水势、光合作用及干物质分配的影响

采用盆栽水分试验 ,研究了不同生育期短期干旱处理对水稻叶水势、光合作用和干物质分配的影响 .结果表明 ,干旱胁迫后 ,水稻叶水势低于对照 ,午后叶水势回升缓慢 .凌晨叶水势随土壤含水量的降低而降低 ,表现为阈值反应 .叶片净光合速率与凌晨叶水势密切相关 ,低于凌晨叶水势临界值 ,水稻叶片净光合速率急剧下降 .在水稻抽穗期和灌浆期叶片净光合速率显著下降的凌晨叶水势临界值为 - 1.0 4和- 1.13MPa,对应的土壤含水量阈值分别为饱和含水量的 6 1.0 %和 5 0 .9% ,土壤水势分别为 - 0 .133和- 0 .2 4 0MPa .干旱胁迫下单叶净光合速率的日变化规律表现为 :胁迫较轻时 ,单叶净光合速率在正午附近出现低谷 ;胁迫严重时 ,净光合速率全天低于对照 ,且不及对照的一半 .短期干旱后 ,水稻叶、根、穗的分配指数均降低 ,茎鞘的分配指数升高 .本研究可为水稻节水灌溉管理和水分限制下水稻的生长模拟提供生理基础和理论依据 .

水分胁迫下水稻剑叶中多胺含量的变化及其与抗旱性的关系

以 6个中熟水、陆稻品种为材料 ,研究了在不同土壤水分状况下剑叶中腐胺 (Put)、亚精胺 (Spd)和精胺 (Spm)含量的变化及其与抗旱性的关系。结果表明 ,供水充足 (对照 )的叶片中Put、Spd和Spm含量随叶片的衰老而缓慢下降 ,与品种的抗旱性没有明显联系。水分胁迫处理 (土壤水势保持 -0 0 5MPa)后 ,叶片中Put、Spd和Spm含量均显著增加 ,增加的量以Put >Spd >Spm ;抗旱品种叶片中多胺累积开始较早、持续时间长 ,Spd和Spm的相对含量 (胁迫处理 对照 )较高 ,干旱敏感性品种则相反。Put和Spd或Spm开始在叶片中累积的叶水势阈值 ,抗旱品种分别为 -0 5～ -0 53MPa和-0 61～ -0 62MPa,干旱敏感性品种分别为 -0 72～ -0 74MPa和 -0 81～ -0 83MPa。Spd和Spm的相对含量与品种的抗旱系数呈极显著的正相关 (r =0 92 1 ～ 0 984 ,P <0 0 1 ) ,Put的相对含量与抗旱系数的相关值因测定时期不同而异。在水分胁迫初期分别用 0 1mmol LSpd或Spm喷施叶片 ,籽粒产量较仅用清水处理的对照显著增加 ,用 0 2mmol LPut处理后的产量与对照差异不显著 ,用 1mmol LMGBG [甲基己二醛 双 (脒基腙 ) ,多胺合成抑制剂 ]处理 ,产量较对照显著降低。上述结果说明 。

抗氧化剂对月季切花失水胁迫耐性和SOD、POD活性的影响

研究从细胞膜保护酶水平上明确抗氧化剂可改善月季切花失水胁迫耐性的机理 ,选用中度耐失水品种‘Lambda’和耐失水品种‘BlueCard’。抗氧化剂为 3g·L-1的抗坏血酸和 10 μmol·L-1的 β 胡萝卜素 ,在失水胁迫处理前 8℃下茎基吸收 12h。失水胁迫以温度 2 2～ 2 5℃、相对湿度为 30 %～ 5 0 %干置 2 4h。处理结束时 ,上述 2品种未经抗氧化剂处理的对照花材的花朵水势分别降到 - 1.31和 - 1.15MPa;2种抗氧化剂都能显著提高月季切花失水胁迫后瓶插期间花朵和叶片水势 ,降低花瓣相对电导率和MDA含量 ,维持花瓣相对稳定的SOD和POD活性水平。结果说明 2种抗氧化剂抗坏血酸和 β 胡萝卜素能够延缓月季切花‘Lambda’和‘BlueCard’衰老进程和延长切花瓶插寿命 ,与提高了细胞膜保护酶活性相关。