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1.
To investigate the effects of irrigation regimes on assimilate remobilization, water use efficiency (WUE), relative water content (RWC), photosynthesis and yield of five wheat cultivars, a field experiment was conducted at Shiraz University during the 2008 and 2009 growing seasons. The experimental design was a randomized complete block and treatments were arranged as split-plot in three replicates. There were four levels of water regime including well-watered [irrigation based on 100% field capacity (FC)], excess watered (125% FC), mild drought (75% FC) and severe drought (50% FC) stress, and four bread wheat cultivars (Shiraz, Bahar, Pishtaz and Sistan) and a durum wheat (Yavaros). In all cultivars, progressed leaf senescence at 30 days after anthesis (DAA), was associated with a reduction in chlorophyll content. The reduction was more pronounced in Shiraz and Yavaros than Pishtaz and Sistan. With increasing temperature and remobilization of assimilate to grain, net photosynthesis and stomatal conductance were decreased significantly at 18 DAA compared with 8 DAA. Sistan and Pishtaz cultivars maintained higher RWC than sensitive cultivars of Shiraz and Yavaros under drought stress. The higher WUE in Pishtaz and Sistan was attributed to the effectiveness of a small amount of water in alleviating severe stress during the sensitive stages of growth. Under mild drought stress, controlled soil drying could enhance remobilization efficiency of assimilates in Pishtaz and Sistan and under severe drought, these cultivars had the highest grain yield compared with the other cultivars. Reduction of assimilates remobilization to the grain and 1000-grain weight, caused lower grain yield in Shiraz under severe drought. Overall, controlled soil drying in Sistan and Pishtaz might result in better mobilization of pre-stored assimilates to the grain in arid areas, where a rapid depletion of water resources is threatening crop production.  相似文献   

2.
Drought stress limits crop production in the world. Therefore, employing high-yielding cultivars tolerant to drought is an effective approach to reduce its detrimental effects. To identify drought-tolerant genotypes, 36 wheat genotypes were evaluated during the 2010–2011 and 2011–2012 growth seasons. A field experiment was conducted in a split-plot design with two irrigation treatments (100% field capacity (FC) until harvest and no irrigation after anthesis) as main plots in three replications and genotypes as subplots. Grain yield, its components and drought tolerance indices were measured. Results showed a significant reduction in yield and its components under drought conditions. Grain yield had significant positive correlations with stress tolerance index (STI), mean productivity (MP) index and geometric mean productivity (GMP), while it was negatively correlated with stress susceptibility index (SSI) and tolerance index (TOL) under stress condition. These results indicated that superior genotypes could be selected based on high values of STI, MP and GMP and low value of SSI. The results were validated by principal component analysis (PCA) as it showed genotypes with high PC1 and low PC2 were more desirable. Based on the results, genotypes number 8, 11, 17, 30, 34 and 35 were recognized as suitable for both conditions.  相似文献   

3.
【目的】干旱胁迫影响甘薯叶片光合特性及块根产量,研究通过施肥缓解干旱胁迫机理可为甘薯抗旱高产栽培提供理论依据。【方法】选用食用型甘薯品种“泰中6号”为材料,以硫酸钾(K2SO4)为供试肥料,水分处理设为土壤最大持水量的60%~70%(正常供水W1)和30%~40%(干旱处理W0); 钾肥设K0、 K1、 K2、 K3四个水平,K2O用量分别为0、 12.0、 24.0和36.0 g/m2。分析不同钾肥用量对不同生长时期甘薯叶片相对含水量、 叶绿素荧光参数、 光合特性及收获期块根产量的影响。【结果】在干旱胁迫和正常灌水条件下,施钾处理均显著增加了甘薯叶面积和叶片叶绿素含量,提高净光合速率(Pn),增加光合产物的生产和积累,提高块根产量和收获指数。两种水分条件下,块根产量均以K2处理最高, 干旱胁迫下K2与K3处理差异显著,正常灌水处理不显著。两种水分条件下,甘薯叶片光合参数对钾肥的响应存在显著差异,干旱胁迫下施钾使叶片水分利用效率(WUE)增大,气孔导度(Gs)降低,气孔阻力增大,蒸腾速率(Tr)和胞间CO2浓度(Ci)降低,水分蒸腾量减少; 而正常灌水条件下上述指标对钾肥的响应趋势相反。两种水分条件下施钾均可以增大叶片相对含水量(RWC),提高实际光化学效率(ΦPSII)和最大光化学效率(Fv/Fm),但是干旱胁迫下施钾增幅较大。【结论】干旱胁迫下适量施钾可以提高甘薯的抗旱性,增加甘薯产量,过量施钾使甘薯产量显著降低,而正常水分供应时,稍多钾肥对产量影响不显著。干旱胁迫与正常灌水条件下施钾对叶片光合参数的调控效应存在显著差异。施用钾肥可增大叶面积,提高叶绿素含量和光合性能,调节叶片气孔关闭,增大叶片气孔阻力,减少水分蒸腾损失,增加叶片相对含水量,提高水分利用效率和净光合速率; 施钾还能提高叶片PSⅡ原初光能转换效率和实际光化学效率,减少过剩激发能对光合机构的破坏,提高甘薯叶片的光合能力。干旱条件下钾肥的调节功能优于正常水肥供应。  相似文献   

4.
拔节期干旱是影响冬小麦产量的重要灾害,揭示不同品种对干旱胁迫生理响应的差异,可为鉴选与培育抗旱品种提供指导。选取黄淮海平原不同冬麦区种植面积较大的晋麦47、洛旱2号、石家庄8号、豫麦18和郑麦9023共5个品种和1个抗逆性较弱的品种偃麦20,利用防雨棚开展盆栽试验研究。从籽粒产量以及气孔特性、膜稳定性和渗透调节特性等方面,分析拔节期受水分胁迫后,各品种抗旱性和干旱胁迫响应途径的差异。结果表明:(1)灌溉条件下,晋麦47、洛旱2号和石家庄8号产量较高,豫麦18和偃麦20产量较低。拔节期受干旱胁迫后,晋麦47、洛旱2号和豫麦18产量较高,石家庄8号和偃麦20产量较低。可见,以籽粒产量为抗旱性评价的核心指标,晋麦47、洛旱2号和豫麦18抗旱性较强,石家庄8号和偃麦20抗旱性较弱,郑麦9023抗旱性居中。(2)3个抗旱品种间干旱胁迫响应途径并不一致。与抗旱性较弱的石家庄8号和偃麦20相比,拔节期干旱胁迫下,豫麦18气孔导度较低,气孔调节能力强;洛旱2号细胞渗透势较低,渗透调节能力较强;洛旱2号膜离子渗漏率较低,膜稳定性较强;晋麦47在气孔调节、渗透调节和膜稳定性调节方面与抗旱性较弱的品种无显著差异。研究结果说明,冬小麦品种间响应干旱胁迫的关键途径存在差异。因而品种的抗旱性难以通过单一生理指标科学评价,需要多指标联合鉴定。  相似文献   

5.
干旱胁迫对花生生育中后期根系生长特征的影响   总被引：5，自引：0，他引：5  
花生是较耐旱的经济和油料作物, 长期少雨或季节性干旱是限制花生产量提高的重要环境因子, 也是花生收获前黄曲霉素感染的重要因素。根系是植物吸水的主要器官, 不同土壤水分状况下植物的根系构型可能会表现出显著差异, 进而影响植物根系吸收养分和水分的能力。研究不同土壤水分状况下花生根系形态的发育特征与抗旱性的关系对进一步理解花生的水分吸收、运输、利用和散失机制以及培育抗旱性花生具有非常重要的作用。为明确不同抗旱性花生品种的根系形态发育特征, 探讨其根系形态发育特征对不同土壤水分状况的响应机制, 在防雨棚旱池内进行土柱栽培试验, 研究抗旱型花生品种"花育22号"和干旱敏感型花生品种"花育23号"生育中后期根系生长特征及其对干旱胁迫的响应。设置正常供水和中度干旱胁迫(分别控制土壤含水量为田间持水量的80%~85%和45%~50%)2个水分处理, 分别在花针期、结荚期和饱果期进行取样,根长、根表面积和体积扫描后通过WinRhizo Pro Vision 5.0a程序进行分析; 收获时测定产量和抗旱系数(干旱胁迫处理与正常供水处理下产量之比)。结果表明, "花育22号"具有较高的产量和抗旱系数, "花育23号"对干旱胁迫的适应性小于"花育22号"。抗旱型品种"花育22号"具有较大的根系生物量、总根长和根系表面积, 且深层土壤内根系表面积和体积大于"花育23号"。与正常供水处理相比, 干旱胁迫显著降低2个品种花针期的根系总根长、根系总表面积和总体积, 对结荚期和饱果期根系性状无显著影响; 干旱胁迫增加2个品种生育中后期40 cm以下土层内的根长密度分布比例、根系表面积和体积, 但"花育23号"各根系性状增加幅度小于"花育22号"。干旱胁迫处理下20~40 cm和40 cm以下土层内根系表面积和体积分别与总根长、总表面积和总体积呈显著或极显著正相关, 而正常供水处理下0~20 cm土层内根系表面积和体积与整体根系性状表现极显著正相关。总体而言, 具有较大根系和深层土壤内较多的根系分布是抗旱型花生的主要根系分布特征; 土壤水分亏缺条件下, 花生主要通过增加深层土壤内根长、根系表面积和体积等形态特性调节植株对水分的利用。  相似文献   

6.
ABSTRACT

The selection response of wheat (Triticum aestivum L.) under water-limited condition can be enhanced through breeding novel genotypes possessing drought-adaptive and yield-related agronomic and physiological traits. The objective of this study was to evaluate terminal drought tolerance among bread wheat genotypes and select superior parents for breeding. Agronomic and physiological responses of 28 wheat lines were assessed under well-watered (WW) and terminal drought (TD) treatments using a 7?×?4 alpha-lattice design under rainout shelter (RS) and glasshouse (GH) environments. Significant (p?≤?0.05) genotype?×?environment interaction effects were observed for number of days to heading (DTH), number of days to maturity (DTM), number of productive tillers per plant (TN), grain yield (GY), thousand kernel weight (TKW), stomatal conductance (SC), leaf canopy temperature (LCT) and chlorophyll content index (CCI) suggesting varied genotypic response under WW and TD treatments. Correlation analysis revealed significant associations TN and GY (r?=?0.67; p?≤?0.001), TKW and GY (r?=?0.72; p?≤?0.001), CCI and GY (r?=?0.39; p?≤?0.05) under TD treatment. Drought tolerant wheat genotypes such as LM100, LM72, LM22 and LM95 are useful for direct cultivation and for developing breeding populations with enhanced yield performance.  相似文献   

7.
This study aims to explain the effects of silicon (Si) foliar application on gas exchange characteristics, photosynthetic pigments, membrane stability and leaf relative water content of different wheat cultivars in the field under drought stress conditions. The experiment was arranged as a split-split plot based on randomized complete block design with three replications. Irrigation regime (100%, 60%, and 40% F.C.), silicon (control and Si application) and wheat cultivars (Shiraz, Marvdasht, Chamran, and Sirvan) were considered as main, sub and sub-sub plots, respectively. This study was carried out at the Research Farm of the Collage of Agriculture, Shiraz University, Iran, during 2012–2013 growing season. The results showed that foliar application of silicon increased the leaf relative water content, photosynthesis pigments (chlorophyll a, b and total chl and carotenoids), chlorophyll stability index (CSI) and membrane stability index (MSI) in all wheat cultivars, especially in Sirvan and Chamran (drought tolerant cultivars), under both stress and non-stress conditions. However, more improvement was observed under drought stress as compared to the non-stress condition. In contrast, these parameters decreased under drought stress. Si significantly decreased electrolyte leakage in all four cultivars under drought stress conditions. Furthermore, the intercellular carbon dioxide (CO2) concentration (Ci) increased under drought stress. Si application decreased Ci especially under drought stress conditions. Net photosynthesis rate (A), transpiration rate (E) and stomatal conductance (gs) were significantly decreased under drought conditions. Under drought, Si applied plants showed significantly higher leaf photosynthesis rate, transpiration rate, and stomatal conductance. Intrinsic water use efficiency (WUEi) and carboxylation efficiency (CE) decreased in all cultivars under drought stress. However, the silicon-applied plants had greater WUEi and CE under drought stress. The stomatal limitation was found to be higher in stressed plants compared to the control. Exogenously applied silicon also decreased stomatal limitation. Overall, application of Si was found beneficial for improving drought tolerance of wheat plants.  相似文献   

8.
A study was conducted to investigate the sensitivity of physiological traits under different soil water availability in summer maize (Zea mays L.). Plant growth (plant height and stem), water relations (relative water content), gas exchange (net photosynthesis rate, stomatal conductance and transpiration rate) and nutrient levels were measured after 5, 10, 15 and 20 days of drought with different soil water availability. We found that all these physiological traits were inhibited by drought stress, but they showed differing levels of sensitivity with different soil water availability. Our results show that stomatal conductance was the most sensitive in mild drought conditions, that carbon accumulation was more sensitive than the other parameters in moderate drought, and that height and stem showed the largest response ratio in severe drought conditions. Different traits performed differently under drought conditions; thus, choosing an adequate index for evaluating soil water availability is necessary for maize cultivation.  相似文献   

9.
旱涝交替胁迫条件下粳稻叶片光合特性   总被引：3，自引：2，他引：3  
为研究分蘖期和拔节期旱涝交替胁迫对粳稻叶片光合特性和产量的影响,于2013年进行盆栽试验,分别在粳稻分蘖期(tillering stage,T)和拔节期(jointing stage,S)设置涝-轻旱(light drought,LD)和涝-重旱(sever drought,HD)共4个旱涝交替胁迫处理,其中分蘖期涝保持水深10 cm,拔节期涝保持水深15 cm,同时以浅水勤灌(CK)为对照,测定叶片净光合速率、气孔导度、潜在水分利用效率和胞间二氧化碳浓度以及最终产量等。结果表明,胁迫结束时,T-HD处理净光合速率极显著低于CK和T-LD处理(P0.01);T-LD和T-HD处理气孔导度和胞间二氧化碳浓度均极显著低于CK(P0.01);S-HD处理净光合速率极显著低于CK(P0.01),且气孔导度比CK低62.73%(P0.01);S-LD和S-HD处理胞间二氧化碳浓度呈升高趋势,且S-LD和S-HD处理潜在水分利用效率均低于CK。复水至10月10日,各处理净光合速率、气孔导度和胞间二氧化碳浓度均显著高于CK(P0.05)。相同光强下,各处理净光合速率低于CK,但光补偿点、光饱和点和暗呼吸速率均高于CK,并且提高了水稻CO_2响应曲线的净光合速率。但各处理最终产量均显著低于CK(P0.05)。研究结果可为分析水稻干物质积累、灌溉水利用效率等提供依据。  相似文献   

10.
Drought and low amounts of organic matter are two main constraints in arid and semiarid regions and their adverse effects on soils and plants can be alleviated by biochar (B). Therefore, the influence of 0 (0B), 1.25 (1.25B), 2.5 (2.5B) and 5% (5B) cattle-manure biochar on the growth and physiological traits of spinach and physical characteristics of postharvest soil under field capacity (FC), 0.7FC and 0.55FC conditions was evaluated. Drought decreased stomatal conductance (SC), water use efficiency (WUE), shoot dry matter yield (SDMY), soil water repellency (WR) and saturated hydraulic conductivity (Ks) by 13–45%, 3–17%, 27–51%, 48–60% and 26–36%, respectively. Whereas, all B treatments increased SC, Ks and total porosity by 11–63%, 82–221% and 2–12%, respectively. Application of 1.25B increased SDMY and WUE, whereas higher B levels were ineffective, i.e. 2.5B did not significantly affect the measured parameters and 5B reduced them. At all B levels, drought reduced SDMY. However, the lowest decrease in SDMY was observed by 1.25B. Despite their positive influence on soil’s physical quality, high B levels induced excessive salinity. Therefore, a low B level (1.25B) may be recommended since it provides positive impacts on the plant’s growth and yield while mitigating the adverse effects of drought.  相似文献   

11.
不同水分和施氮量对催吐萝芙木光合特性和生长的影响   总被引：3，自引：0，他引：3  
在西双版纳干季, 田间试验探讨了水分胁迫下施氮量[不施氮、低量施氮(1.25 g·株-1)、高量施氮(3.75 g·株-1)]对两年生催吐萝芙木(Rauvolfia vomitoria Afzel.)生长和光合的影响。结果表明: 水分胁迫显著降低了催吐萝芙木叶片相对含水量(LRWC), 但LRWC仍在85%以上, 属于低度水分胁迫, 其最大净光合速率、气孔导度、比叶面积、茎重比以及株高、基径和生物量的相对生长速率均较无水分胁迫时低。水分胁迫下, 低量施氮可使最大净光合速率、蒸腾速率、根重比升高, 使株高、基径和生物量的相对生长速率增加, 从而明显增加最终根产量; 而高量施氮则会增加幼树对干旱的敏感性, 加重干旱对催吐萝芙木光合和生长的抑制作用。水分与施氮量交互作用对催吐萝芙木叶片相对含水量、最大净光合速率、水分利用效率、比叶面积和根重比的影响显著, 表明施氮量对其影响视水分胁迫状况而不同。因此, 为获得催吐萝芙木最大根产量, 应在干季收获期前少量施用氮肥。  相似文献   

12.
In this study, we selected 180 accessions from different wild relatives of wheat (Aegilops–Triticum species) and tested them in the presence of a tolerant and a sensitive control variety under well-watered and drought-stressed conditions. The results of analysis of variance for dry masses and all measured root traits showed that water regimes, accession and species main effects were highly significant. Drought stress significantly declined shoot dry mass (59.42%), root length (37.85%) and the total number of branch roots (36.25%), but increased the root-to-shoot ratio (75.00%), specific root length (64.19%) and root tissue density (29.46%). Principal component analysis for 182 individuals and 12 species groups identified two components that explained 75.67 and 82.39% of the total variation in dry mass and root traits under drought-stressed conditions, respectively. Taking together, our results identified 12 accessions with superior tolerance to drought stress. Remarkably, four species of wild relatives – Ae. cylindrica (DC genome), Ae. neglecta (UM genome), Ae. speltoides (B genome) and Ae. tauschii (D genome) – responded well to drought stress. The potential of these species could be used for molecular analysis such as marker assisted selection and gene mapping, ultimately aimed at breeding for root traits with improved adaptation to drought environments.  相似文献   

13.
The frequency and severity of drought is predicted to rise in many parts of the world. Considering that drought is the main constraint on rain-fed wheat crop production, both agronomic and genetic measures have been taken to minimize yield losses under drought. Beyond its role as a micronutrient, chloride also acts as an osmoticum, implicated in the regulation of stomatal aperture. This study explores the potential for chloride fertilization of Australian bread wheat (Triticum aestivum L.) to minimize grain yield losses caused by drought stress. For this, two drought-tolerant commercial genotypes (Mace and Gladius) and a well-studied drought-tolerant genotype used in wheat breeding (RAC875) were treated with ammonium chloride, potassium chloride, or ammonium bicarbonate, the latter two treatments served as controls for chloride and ammonium, respectively. Plants were grown under either a watered or water-restricted (drought) regime. The genotype RAC875 was found to accumulate leaf chloride at a significantly higher level than the other genotypes under optimal growth conditions. Under drought conditions, top-dressing RAC875 plants with ammonium chloride resulted in up to a 2.5-fold increase in grain number and this effect was not seen when plants were top-dressed with either of the control fertilizers. The ammonium chloride treatment also minimized losses of grain yield in RAC875 plants grown under drought. Treatment effects were accompanied by an increase in stomatal conductance. These results collectively suggest that the compound fertilizer ammonium chloride can improve drought tolerance of wheat.  相似文献   

14.
Phytohormones have an essential ability to adapt to abiotic stresses, including drought stress (DS), by mediating physiological and molecular processes. Arbuscular mycorrhizas (AMs) can enhance tolerance of DS, but the information regarding phytohormone changes in AM plants exposed to DS is little known. Trifoliate orange (Poncirus trifoliata) seedlings colonized by an AM fungus Funneliformis mosseae were subjected to DS and well-watered for 6 weeks. Plant growth performance, gas exchange, indole-acetic acid (IAA), gibberellins (GAs), brassinosteroids (BRs), abscisic acid (ABA), methyl jasmonate (MeJA) and zeatin riboside (ZR) were determined. The 6-week DS treatment strongly restricted root mycorrhizal colonization. Mycorrhizal inoculation significantly increased plant growth parameters under DS, as compared with non-mycorrhizal treatment. Mycorrhizal treatment also induced significantly higher leaf-relative water content, net photosynthetic rate, transpiration rate and stomatal conductance but lower intercellular CO2 concentration and leaf temperature under DS, compared with non-mycorrhizal treatment. Mycorrhizal plants under DS condition represented significantly higher leaf ABA, IAA, GAs, BRs and ZR levels than non-mycorrhizal plants. The study, hence, suggested that mycorrhizal inoculation induced the changes of gas exchange and endogenous phytohormone levels to enhance drought tolerance in trifoliate orange.  相似文献   

15.
Drought is an important limiting factor which can cause major loss in barley productivity. A field experiment was conducted to investigate the effects of irrigation regimes on assimilate remobilization and photosynthetic characteristics of five barley cultivars in 2012 and 2013. There were four levels of irrigation including well-watered [soil moisture content in root depth kept at 100% field capacity (FC)], mild drought (75% FC), severe drought (50% FC), and very severe drought (25% FC). Results showed that Karoon and Valfajr cultivars had the maximum net photosynthetic rate (Pn) ranged from 16.3 to 19.3 µmol CO2 m?2 s?1 under very severe drought. Stomatal conductance (gs) was affected by drought so that Karoon and Valfajr had the lowest gs under severe and very severe drought. By improving the drought, remobilization efficiency in Karoon and Valfajr increased from 18.3% in well-watered to 54.1% under severe drought. In both years under severe and very severe drought, maximum 1000-grain weight and grain yield was obtained in Valfajr and Karoon. Overall, in arid areas, applying suitable irrigation regimes such as mild or severe drought can control soil drying, so that suitable cultivars such as Karoon and Valfajr can rehydrate overnight, and yield might not be inhibited severely.  相似文献   

16.
干旱胁迫及复水对耐旱枸杞水力学特性的影响   总被引：1，自引：1，他引：0  
耐旱枸杞是西北干旱地区重要的经济作物,为进一步明确枸杞水分运输特性,提高农业生产潜力,在甘肃省古浪县农业示范基地(37.09°N,102.79°E)以2年生‘宁杞1号’、‘宁杞5号’和‘蒙杞1号’3个枸杞品种苗木为试验材料,设计3个处理[N:正常水分;M:中度干旱;S:重度干旱],研究干旱胁迫对光合速率、气孔导度、冠层和根系导水率的影响,以及干旱胁迫后复水对枝条导水率的影响。结果表明:随着干旱程度增加,枸杞冠层、枝条和根系导水率均下降,‘宁杞5号’在干旱胁迫后植株导水率的减小和根系导水阻力在整个植株中所占比例的增大最显著;通过拟合木质部脆弱性曲线发现,‘宁杞1号’导水率损失50%时木质部水势显著高于‘宁杞5号’和‘蒙杞1号’。枸杞叶片净光合速率和气孔导度与植株叶片导水速率具有显著相关性。干旱胁迫复水后植物生长主要取决于根系恢复吸水的能力,干旱胁迫复水4 d后苗木导水率呈现不同程度的恢复,‘蒙杞1号’导水率恢复速度最快,并出现显著补偿效应,恢复速度最慢的为‘宁杞5号’。综合分析表明,枸杞耐旱特性与导水能力有关,根系导水对干旱胁迫的敏感性可以反映植株持续抗旱能力,干旱胁迫复水后根系导水率恢复能力和补偿效应对植株在逆境条件下土壤水分利用具有显著影响,调控根系导水率对于提高土壤水分利用率具有重要意义。  相似文献   

17.
Young trees of Norway spruce (Picea abies (L.) Karst.) were grown in 120 litre pots under two different ozone levels in open-top chambers for three seasons, 1992–1994. The ozone treatments were charcoal filtered air (CF, average 24 h seasonal mean 6.5 ppb) and non-filtered air with extra ozone aiming to track 1.5 times ambient (NF+, average seasonal mean 34 ppb). In addition, half of the spruce trees in Aug – Sep each season recieved a drought period of between five and seven weeks. The remaining half were kept well-watered. The soil water content, the needle water potentials, and the gas exchange as well as the chamber micro climate were measured before, during and after the drought period. Furthermore, the growth of the trees was measured as biomass increase. During the 1993 drought period, where the trees experienced a moderate drought stress, the trees grown in NF+ consumed soil water faster and showed a higher needle conductance compared to CF. However, no negative effects were found on needle water potential or growth. During the more severe 1994 drought stress period we did not find any differences between the two ozone treatments in soil water consumption, needle conductance or needle water potential. There was a significant negative effect of the high ozone treatment on tree biomass of the well-watered trees. Total plant biomass was reduced 18 % and stem biomass was reduced as much as 28 %. The negative effect of ozone on tree biomass was much smaller for the droughted trees.  相似文献   

18.
以“XR4347”冬小麦品种为供试作物,在温室内开展盆栽试验。试验设置不施氮（N0）和施氮（N1, 1.5g·盆1）2个氮素水平,每个水平下设置3种水分处理模式,即全程充分灌水（CK）、干旱锻炼后复水（PW）和干旱锻炼后复旱（PD）,研究施氮和干旱锻炼后复水/复旱对冬小麦水分利用效率的影响。结果表明：干旱锻炼后复旱使植株水势降低。与CK和PW处理相比,干旱锻炼后复旱对气孔导度（gs）的降低作用大于光合速率（Pn）的下降,因此,提高了叶片和植株水平的水分利用效率。在CK和PW处理下,施氮与未施氮处理相比,叶片的Pn和gs均显著提高,而内在水分利用效率（WUEint, Pn/gs）小幅度增加。PD处理下,施氮对gs的影响大于对Pn的影响,与不施氮（N0）处理相比,施氮（N1）处理下小麦叶片Pn增加4.5%,而gs下降13.6%,因此,WUEint显著提高。干旱锻炼后复旱显著降低了施氮后植株的gs和耗水量,其WUEb和叶片δ13C在施氮后最高,进一步表明干旱锻炼后复旱条件下施氮提高植株的WUEb主要是由于气孔的调控造成的。因此,在干旱缺水地区,将干旱锻炼与施氮结合,不仅可以显著降低植株耗水量、节约灌溉用水、维持作物生长和养分吸收,还可以提高叶片和植株水平的水分利用效率。  相似文献   

19.
The effect of drought preconditioning before anthesis and post-anthesis waterlogging on water relation, photosynthesis, and growth was studied in tomatoes. Tomatoes were grown in pots and exposed to four treatments, whereby the plants were irrigated to 80% field capacity in T1 (control) and T2, 70% of the control (T3), and 50% of the control (T4). Drought was maintained for 30 days from 14 days after transplanting (DAT), and then the plants under T2, T3, and T4 were subjected to waterlogging at 60 and 80 DAT and lasted for 2 days. The results showed that drought pretreatments induced a decrease in leaf water potential, leaf insertion angle, photosynthetic rate, and transpiration rate. The stomatal closure and epinasty observed in response to drought pretreatment represented adaptive mechanisms to the followed waterlogging. The soil redox potential, photosynthetic rate, stomatal conductance, and transpiration rate of un-pretreatment were dramatically decreased by post-anthesis waterlogging; however, T3 was found to effectively enhance tolerance to a waterlogging event by decreasing leaf insertion angle and increasing photosynthetic rate, stomatal conductance, and transpiration rate. Fruit quality and yield were deteriorated considerably by waterlogging. However, T3 caused less damage to fruit quality and yield by post-anthesis waterlogging compared to T2.  相似文献   

20.
ABSTRACT

Drought is a major constraint for agricultural productivity worldwide, and it is likely to further increase. Different strategies are required to mitigate drought stress in plants. In a two-year study that conducted at agronomic research area of the Islamia University of Bahawalpur, we investigated the role of rhizobacteria (RB) and cytokinins (Ck) on drought tolerance, nutrient uptake, yield, and physiological parameters in wheat under drought stress at different developmental stages (tillering, anthesis, and grain filling). Thirteen treatments used were well-watered control plants without RB or Ck, drought at tillering, anthesis, or grain filling without or with RB alone, Ck alone, or combination of both (RB+Ck). In both years, and at the different stages, measured parameters were highest in the well-watered plants but lowest in drought-stressed plants. Application of RB and Ck to drought-stressed plants increased these parameters in the order RB+Ck > RB > Ck. In some cases, under drought stress, there was no difference between inoculation with RB and application of Ck. It was concluded that the combined application of RB and Ck could play a significant role in improving wheat yield and also alleviation of stress under drought condition.  相似文献   

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