首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 125 毫秒
1.
以金沙江干热河谷主要树种坡柳、银合欢、山毛豆实生幼苗为材料,通过盆栽苗自然干旱胁迫,同时以浇水处理为对照,研究了干旱胁迫对坡柳、银合欢、山毛豆3个树种丙二醛含量、膜相对透性及保护酶活性的影响。结果表明,干旱胁迫下3个树种幼苗的细胞膜透性、MDA及SOD, POD酶活性都发生了变化,只是变化的幅度和进程不同。干旱胁迫对银合欢膜系统损伤生成的主要降解产物不是MDA;山毛豆清除活性氧毒害作用主要不是通过SOD和POD的作用;通过叶片相对保水力测定及膜透性、MDA相对含量、酶活性变化情况的分析,3个树种中坡柳耐旱性最强,其次为银合欢,山毛豆居后。  相似文献   

2.
台湾桤木和四川桤木种源苗木对水分胁迫的生理响应   总被引:10,自引:0,他引:10  
采用PEG6000,研究了4种台湾桤木种源和2种四川桤木种源苗木对水分胁迫的生理响应。结果表明:(1)随着水分胁迫强度增加,叶片质膜相对透性增大,四川桤木种源质膜透性比台湾桤木种源增加幅度大。(2)在轻度的水分胁迫下,6个种源SOD活性均呈上升趋势,POD活性的增加只发生在PEG10%的水分胁迫强度以内,轻度水分胁迫下,MDA含量上升幅度小于重度胁迫强度;在PEG30%胁迫处理时,台湾桤木叶片MDA含量平均上升30.22%,而四川桤木上升了40.44%,表明台湾桤木种源膜脂过氧化程度较四川桤木种源轻,受害程度相对要小一些。(3)水分胁迫下,叶片脯氨酸含垃均有不同程度的增加.在PEG20%水分胁迫处理下,各种源脯氨酸积量增加的幅度为:台湾桤木苗栗种源(AF2)(68.9%)〉台湾桤木福建南平种源(AF4)(60.2%)〉台湾桤木台东种源(AF2)(54.7%)〉台湾桤木台中种源(AF1(47.6%)〉四川桤木广元种源(AC2)(39.7%)>金堂种源(AC1)(39.1%)。水分胁迫条件下,叶片可溶性糖含量呈下降趋势。6种种源苗木在水分胁迫条件下,由于脯氨酸的积累,有一定的渗透调节能力,但这种渗透调节能力又是十分有限的。(4)采用隶属函数法,对各种源的抗旱生理进行综合评价,其耐旱牛理强弱的顺序是:AF2、AF1、AF3、AF4、AC2、AC1,台湾桤木比四川桤木具有较强的耐旱生理适应性。从耐旱生理角度讲,凡是适合四川桤木生长的区域,基本上亦适合台湾桤木,在引种载培中,应选择抗旱性稍强一些的台湾桤木苗栗种源和台中种源。  相似文献   

3.
钙素和水分亏缺对黄瓜叶片细胞质膜透性的影响   总被引:16,自引:0,他引:16  
用控制溶液的钙量[加或不加Ca(NO_3)_2]和渗透势(加聚乙二醇6000,202 g/L)的方法,研究了钙素和水分亏缺对黄瓜叶片细胞质膜透性的影响。结果表明:在渗透胁迫下,正常供钙的黄瓜叶片相对含水量(RWC)和膜透性变化较小、MDA增加不显著、SOD活性无明显改变;缺钙植株叶片的RWC随渗透胁迫处理线性下降,膜透性显著增大、MDA含量迅速提高、SOD活性也升高。在正常水分供应下,与供钙植株相比,缺钙植株SOD活性和MDA含量均较高,但RWC和膜透性无差异。在水分胁迫下,缺钙植株MDA和质膜透性与ΔRWC以及MDA与质膜透性之间均呈正相关。这些结果表明在水分胁迫下,缺钙处理叶片保水能力降低,使受害加重;同时,细胞质膜的稳定性降低。膜透性改变可能与在水分胁迫下体内的膜脂过氧化反应密切相关,即缺钙加速了膜脂过氧化反应,从而损害了质膜结构。  相似文献   

4.
干旱胁迫对霸王水分生理特征及细胞膜透性的影响   总被引:3,自引:0,他引:3  
以2年生霸王为试验材料,用盆栽人工控制土壤水分,研究不同梯度土壤水分条件对霸王水分生理特征、丙二醛含量和细胞膜相对透性的影响.结果表明,与充足供水对照(土壤重量含水量为23%)相比,在严重干旱胁迫(土壤含水量为3%)20 d和45 d时,霸王叶水势和叶片相对含水量分别显著降低70.87%和45.54%、26.81%和12.66%;相应的叶片MDA含量和细胞膜相对透性分别显著增加33.81%和21.78%、17.51%和14.98%;严重干旱胁迫30 d使得霸王叶片保水力显著下降;同时随着土壤干旱胁迫程度的增强,霸王日蒸腾耗水量持续下降,且严重干旱胁迫处理的蒸腾耗水量日变化为水平直线型,其余处理均为单峰型.研究发现,严重干旱胁迫下随着胁迫时间的延长,霸王叶水势和叶片相对含水量有增加趋势,而叶片MDA含量和细胞膜相对透性则有减小趋势,它能够通过自身的调节机制,逐渐改善叶片水分状况,降低细胞膜伤害程度,从而适应严重干旱环境.  相似文献   

5.
李潮海  尹飞  王群 《生态学报》2006,26(6):1912-1919
干旱是制约玉米生产最主要的逆境因子。通过在活动式防雨棚下进行盆栽试验,以耐旱性不同的2个玉米杂交种及其亲本自交系为材料,研究了水分胁迫下玉米叶片活性氧代谢的变化及膜脂过氧化水平。结果表明,在水分胁迫下:(1)玉米叶片O2产生速率和H2O2含量升高、活性氧清除酶类SOD、CAT、AsP活性和清除剂AsA含量在生育前期略微升高,在生育后期明显降低,致使膜脂过氧化产物MDA含量在整个生育期,特别在生育后期明显升高;(2)耐旱性不同的玉米材料维持活性氧代谢平衡的能力存在差异,且该差异在生育后期更为明显。耐旱性较强的掖单2号及其亲本叶片昕产生速率和H2O2含量增加幅度小。生育前期SOD、CAT和AsP活性,以及AsA含量增幅大,后期清除酶活性和清除剂含量较高,全生育期内MDA含量增幅小,表现出较强的维持活性氧代谢平衡能力。而耐旱性较弱的掖单13及其亲本正相反;(3)杂交种维持活性氧代谢平衡的能力受亲本维持能力遗传决定。杂交种各指标的相对耐旱值与其两亲本的平均值呈正相关,其中CAT和AsP活性以及AsA含量3个指标差异达显著水平。  相似文献   

6.
模拟干旱胁迫对枣树幼苗的抗氧化系统和渗透调节的影响   总被引:30,自引:6,他引:24  
用不同浓度的PEG-6000对抗旱性不同的1年生枣树(Zizyphus jujuba)幼苗进行渗透胁迫处理后,研究了不同抗旱性品种枣树幼苗的抗氧化酶活性和渗透调节物质含量的变化.结果显示,干旱胁迫下3种枣苗叶片的相对含水量(RWC)均降低,丙二醛(MDA)含量和细胞质膜相对透性均增加.在30%PEG胁迫下除骏枣1号的SOD活性降低外,3个品种枣苗在干旱胁迫下SOD和POD活性都增加;狗头枣2号的过氧化氢酶(CAT)活性在胁迫下明显增加,而木枣1号和骏枣1号的CAT活性均随着胁迫程度的增加而逐渐下降;木枣1号和骏枣1号的APX活性随着胁迫程度的增加先增加后降低,而狗头枣2号明显增加.干旱胁迫下,除骏枣1号的脯氨酸(Pro)含量和木枣1号的可溶性糖含量在30%的胁迫水平下降低(P>0.05)外,3种干旱胁迫水平下3个品种枣苗的Pro和可溶性糖含量均增加.总之,干旱胁迫下,枣苗叶片相对含水量、抗氧化酶(SOD、POD、CAT和APX)活性、渗透调节物质Pro和可溶性糖含量均为:狗头枣2号>木枣1号>骏枣1号,而MDA含量和膜透性均为骏枣1号>木枣1号>狗头枣2号,表明3个品种的抗旱性为:狗头枣2号>木枣1号>骏枣1号,研究结果与其品种的实际抗旱性一致.  相似文献   

7.
不同瑞典能源柳无性系对干旱胁迫的生理响应   总被引:1,自引:0,他引:1  
以瑞典能源柳无性系2、4、C、E的一年生盆栽扦插苗为材料,采用土壤持续强化干旱胁迫实验,系统测定不同胁迫阶段叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性,以及丙二醛(MDA)、可溶性蛋白含量和株高净生长量,并采用隶属函数模型综合评定了不同能源柳无性系的耐旱性。结果表明:(1)各能源柳无性系叶片的保护酶活性随干旱胁迫的加剧均呈现先增后降趋势:土壤水分含量>11.4%时,SOD、POD和CAT活性均呈增长趋势,三者协同作用;土壤水分含量<11.4%,能源柳无性系2、4的CAT和POD活性显著降低,细胞膜受损。(2)各无性系MDA含量随干旱胁迫的加剧呈增长趋势,土壤含水量降至11.4%时,MDA含量增长显著,其中能源柳无性系4变化最为剧烈。(3)各无性系可溶性蛋白含量随干旱胁迫的持续而增加,但当土壤含水量低于8.1%时有所下降。(4)各能源柳无性系胁迫阶段株高净生长量随干旱胁迫的加剧而降低。(5)隶属函数综合分析发现,4个无性系耐旱潜力表现为能源柳C>能源柳E>能源柳2>能源柳4。  相似文献   

8.
刘建新  胡浩斌  赵国林 《生态学报》2008,28(4):1579-1585
通过盆栽土培试验研究了干旱胁迫下多裂骆驼蓬(Peganum multisectum Bobr)叶片乙烯释放、多胺含量、活性氧水平及细胞膜透性的动态变化.结果表明,随着土壤干旱强度的增加和胁迫时间的延长,多裂骆驼蓬叶片内丙二醛(MDA)含量和细胞膜透性呈递增变化趋势;轻度胁迫下,乙烯产生速率、多胺(Put、Spm、Spd)、活性氧(O2-·、H2O2)和MDA含量及多胺氧化酶(PAO)活性随胁迫时间延长无明显变化;中度和重度胁迫初期(胁迫后0~30d)腐胺(Put)、精胺(Spm)和亚精胺(Spd)含量快速提高,乙烯生成速率下降,而O2-·、H2O2、MDA含量和PAO活性相对平稳;胁迫后期(胁迫后45~75d)乙烯生成速率增高,Put、Spm和Spd含量下降, O2-·、H2O2和MDA含量大幅度增加,膜透性增大,且乙烯释放与O2-·、H2O2含量呈显著正相关.表明中度和重度胁迫下多裂骆驼蓬叶片存在乙烯和多胺合成的相互制约,乙烯释放增加诱导活性氧积累导致膜透性急剧增大.  相似文献   

9.
外源芦丁预处理对水分胁迫下玉米幼苗的生理效应   总被引:4,自引:1,他引:3  
以玉米(Zeamays L.)品种'郏单958'为材料.采用营养液水培法,研究了外源芦丁(Rutin)对聚乙二醇(PEG)胁迫下幼苗叶片质膜相对透性、脯氨酸、可溶性糖含量及保护酶活性的影响.结果显示:(1)在15%PEG-6000胁迫下,玉米叶片的MDA含量、质膜相对透性、脯氨酸和可溶性蛋白质含量均显著增加,保护酶SOD、CAT、POD活性显著升高.(2)一定浓度芦丁(>0.40 g/L)预处理可显著抑制水分胁迫下玉米幼苗叶片MDA含量的上升,降低叶片质膜相对透性,并诱导SOD、POD和CAT活性提高.降低脯氨酸和可溶性蛋白质含量.说明外源芦丁能够提高玉米幼苗的抗氧化作用,缓解水分胁迫引起的膜脂过氧化,保护细胞膜免受或减少损伤·达到提高植物抗旱性的目的.  相似文献   

10.
增强UV-B辐射与干旱复合处理对小麦幼苗生理特性的影响   总被引:18,自引:0,他引:18  
为研究由于平流层臭氧层减薄紫外线B辐射增强在干旱地区对春小麦生理特性的影响的特殊性,模拟平流层臭氧减少20%时辐射到地表的紫外线B(UV-B,280-315nm)的增强和水分胁迫(-0.5Mpa,聚乙二醇PEG-6000处理获得),通过测定两种胁迫下春小麦(Triticum aestivum L.)叶绿素含量、类黄酮含量、水势、细胞膜相对透性、超氧歧化酶(SOD)活性及丙二醛(MDA)含量,研究了增强UV-B辐射和水分胁迫复合作用对温室种植的小麦幼苗生理生化的影响。实验结果表明,虽然水分胁迫和UV-B辐射单独或复合处理都使春小麦的叶绿素含量降低,但仅UV-B辐射增强单独处理显著地降低小麦叶绿素a、b和总叶绿素的含量,而水分胁迫以及复合处理对叶绿素的含量的降低作用不显著。两种胁迫无论是单独作用还是复合作用均能使类黄酮含量升高,并且处理第3天比第1天高出近50%,复合处理下类黄酮的含量大于两个因子单独处理。UV-B辐射和水分胁迫处理1d对春小麦叶片的相对电导率的影响不明显,处理3d后两种胁迫下相对电导率均上升,表明膜透性增加,其中水分胁迫作用下增加尤其明显。膜质过氧化产物丙二醛的含量,在两种因子单独和复合作用下都升高,说明膜的生理功能受到了一定的不利影响。活性氧清除剂超氧化物歧化酶(SOD)的活性在各种处理下,都没有发生改变。虽然增强的UV-B辐射和干旱处理一样,会显著降低植物水势,但是,UV-B辐射与干旱同时处理时叶片水势降低的程度,不但没有比两者分别处理时降低程度之和低,而且比单做干旱处理时的降低程度还低,这表明UV-B辐射和干旱胁迫同时处理时,UV-B辐射不但没有加重水分胁迫,反而减轻了干旱对春小麦生长的胁迫。由此可以认为,在干旱条件下,增强UV-B辐射不会加剧而是有利于提高小麦对干旱的抗性。  相似文献   

11.
强旱生小灌木绵刺劈裂生长过程中的水分特征   总被引:3,自引:0,他引:3       下载免费PDF全文
 绵刺(Potaninia mongolica)是西鄂尔多斯-东阿拉善地区特有的单种属残遗植物。 选取内蒙古磴口县境内具有绵刺群落的草原化荒漠区为研究样区,于2002~2003年每年8月1~5日采集未劈裂、正在劈裂和已劈裂植株,运用PV技术对不同劈裂生长状态绵刺的多种水分关系参数(φssat、φstlp、ROWCtlp、RWCtlp、Δφ、εmax等)进行了测定,从绵刺保持膨压的能力和途径两方面进行了深入探讨;同时结合同一项目研究中绵刺劈裂生长过程中抗氧化酶系统和内源激素方面的研究成果,综合分析并探讨了绵刺劈裂生长的发生机理及其环境适应性。结果表明:1)未劈裂绵刺主要通过增加细胞内溶质(如脯氨酸),减少细胞内的水分丧失来进行渗透调节,从而在干旱胁迫下能够维持正常的膨压。2)已劈裂绵刺通过渗透调节和高的组织弹性两条途径来共同保持膨压,以抵抗不良的生存环境;同时对环境水分胁迫具有较高的敏感性。3)3种状态绵刺保持膨压的能力由强到弱依次为:未劈裂绵刺、正在劈裂绵刺、已劈裂绵刺。4)劈裂的发生导致绵刺保持膨压能力的降低,同时耐旱方式和途径发生了变化。  相似文献   

12.
Shoot water relations and morphological responses to drought preconditioning were studied by subjecting 5-month-old seedlings of three provenances of Eucalyptus globulus to different water regimes for 36 days in a greenhouse pot study. Moderately stressed plants were watered every 6 days and severely stressed plants were watered every 9 days. Control plants were watered daily. Drought cycles induced significant changes in morphological and physiological characteristics. Preconditioned seedlings were smaller in size, root collar diameter, height, and leaf area than control seedlings. Shoot/root ratio was not affected by drought. Osmotic potential at full turgor (ψπFT) and osmotic potential at turgor loss point (ψπTLP) were significantly lower and the magnitude of osmotic adjustment was significantly higher under the severe than under the moderate stress treatment. In severely stressed plants a decrease of turgid mass/dry mass contributed to osmotic adjustment. In a subsequent acclimation test, preconditioned seedlings showed higher values of stomatal conductance, predawn relative water content and water potential and lower mortality than control plants. These variables were significantly related to ψπFT. We assume that the reduced leaf area and osmotic adjustment observed in preconditioned seedlings contributed to drought acclimation in the selected E. globulus provenances leading to better rates of gas exchange and improved water status than non-conditioned plants. Provenances exhibited differences in their responses to drought, albeit mainly morphological differences. E. globulus subsp. bicostata from Tumbarumba grew more quickly (larger diameter and height relative growth rate) than the other provenances, implying a greater ability to tolerate water stress. It can be expected that preconditioned seedlings will display greater tolerance of water stress than non-conditioned plants and perform better during early establishment (higher survival and early growth).  相似文献   

13.
To assess the potential of short-term screenings for drought resistance at the seedling stage to detect ecotypic variation and predict field performance, we studied the responses to water deficit of seedlings of Pinus canariensis from five geographic origins under controlled conditions and compared these responses with the performance of provenances in a multi-site field trial. Leaf water potential, the osmotic component, leaf chlorophyll fluorescence and growth and biomass partitioning were measured as seedlings were subjected for 11 days to two levels of osmotic potential generated by polyethylene glycol (PEG 6000), −1 MPa (slowly imposed water deficit; S) and −1.5 MPa (fast imposed water deficit; F), and a control treatment (no PEG added to the nutrient solution; C). Leaf water potential declined to final mean values of −1.2, −2.7 and −4.7 MPa in the C, S and F treatments, respectively. The ratio of variable to maximum chlorophyll fluorescence declined to final mean values of 0.77, 0.66 and 0.40 in the C, S and F treatments, respectively, with no differences amongst provenances. All provenances showed an active osmotic adjustment (OA) in response to water deficit which varied depending on the drying rate. A slow imposition of water deficit favoured solute accumulation. Pooling all treatments, the index of OA ranged from 0.28 to 0.40, but rose considerably when only C and S treatments were considered (0.56 to 0.70). There was a positive and significant correlation between the overall index of OA (all treatments pooled) and the drought period in the site of origin, suggesting ecotypic variation in OA as a result of drought duration. Seedlings allocated more dry matter to roots than shoots when subjected to moderate and slowly imposed water deficit; only one provenance showed no increase in the root to shoot ratio at the end of the treatment period compared with control seedlings. Responses to controlled water deficits were only qualitatively related to performance (survival and growth) of provenances in several field sites, indicating the involvement of complex mechanisms to cope with drought under natural conditions. However, the provenance with the highest overall index of OA outgrew and outsurvived the other provenances in the most arid site, and the only provenance not modifying the root to shoot ratio in response to water deficit survived the least in all field sites. Acclimation of root to shoot ratio and net solute accumulation to water deficit could hence favour drought-tolerance beyond the seedling stage and be used as preliminary predictors of field performance.  相似文献   

14.
荒漠植物蒙古扁桃水分生理特征   总被引:3,自引:0,他引:3       下载免费PDF全文
 蒙古扁桃(Prunus mongolica)是荒漠区和荒漠草原的水土保持植物和景观植物,是蒙古高原古老残遗植物,对其深入研究对于了解蒙古高原植被演替以及对当地生态环境的稳定和恢复有着重要意义。该实验采用PV技术和自然脱水法探讨了蒙古扁桃的水分生理特性。结果表明:在自然状态下,蒙古扁桃幼苗叶片的相对含水量为69%,饱和含水量为117%,临界饱和亏为48%,水势为-0.85 MPa。经 5% PEG-Hoagland (-0.46 MPa)干旱胁迫处理3 d后,其相对含水量、临界含水量和水势分别下降到48%、39%和 -1.97 MPa,而饱和含水量和束缚水与自由水比值分别增加到187%和11.94。对失水率分析的结果表明:在正常水分状态下,蒙古扁桃幼苗经102 h自然脱水后失水达到平衡,而经过干旱胁迫处理3 d后,其失水率曲线斜率变小,失水过程明显减缓,失水最终达到平衡的时间延长到152 h,其保水能力显著提高。将旱生植物蒙古扁桃的失水率曲线与中旱生植物长柄扁桃(P. pedunculata) 的失水率曲线相比较发现,蒙古扁桃的耐脱水能力明显强于中旱生植物长柄扁桃。PV曲线(Pressure-volume curve)分析结果表明:蒙古扁桃饱和含水量渗透势(Ψπ100)和零膨压渗透势 (Ψπ0)很低,分别为-2.49 MPa和-3.11 MPa,而Ψπ100和Ψπ0差值较大(0.62 MPa),表明其维持膨压的能力很强。其细胞壁弹性模量值低(4.18 MPa)进一步表明,蒙古扁桃具有很强的膨压调节能力。蒙古扁桃幼苗失去膨压时的渗透含水量(ROWCtlp)为80%,这是其细胞壁特性所决定的渗透调节能力的基础。蒙古扁桃质外体含水量(AWC, %)较高(79%),因而具有较高的束缚水与自由水比值(7.76),这是其耐脱水性的生理基础。总之,蒙古扁桃叶水势、渗透势低有利于其根部对深层土壤水分的吸收,而较高的束缚水与自由水比值及较低的细胞壁弹性模量是其耐脱水的生理基础。  相似文献   

15.
不同种源乌桕幼苗对干旱胁迫的生理响应   总被引:3,自引:0,他引:3  
以不同种源1年生乌桕幼苗为材料,采用盆栽控水试验研究了持续干旱条件下其外部形态及主要生理指标的变化,探讨各种源乌桕的抗旱性特性与差异。结果显示:(1)随着干旱持续时间的延长,各种源乌桕幼苗生长均受到不同程度抑制,外形表现出明显的缺水特征;其叶片相对含水量逐渐减小,复水后明显回升。(2)在极度干旱条件下(停水后第12天),幼苗叶片净光合作用速率仍维持一定的强度,而且细胞膜透性的变化不显著;在干旱胁迫条件下,幼苗叶片的过氧化物酶和超氧化物歧化酶活性增强,可溶性糖和可溶性蛋白质质量分数增加,丙二醛含量上升,脯氨酸积累,复水后呈现相反的变化趋势。(3)极度干旱条件下,不同种源乌桕幼苗间除丙二醛和相对电导率外,其它生理指标的变化差异显著或极显著,即不同种源具备比较稳定的抗旱性差异。(4)采用隶属函数法对不同种源幼苗的抗旱性分析发现,安徽黄山、河南商城两种源综合评价指数最大,为抗旱性较强的种源。研究表明,各种源乌桕幼苗能够通过调控自身保护酶活性和渗透调节物质含量来有效缓解干旱胁迫的伤害,从而表现出较强的抗旱性和适应性,但种源间存在稳定的差异,并以安徽黄山和河南商城种源抗旱性较强,可应用推广于季节性干旱区造林。  相似文献   

16.
Climate projections propose that drought stress will become challenging for establishing trees. The magnitude of stress is dependent on tree species, provenance, and most likely also highly influenced by soil quality. European Beech (Fagus sylvatica) is of major ecological and economical importance in Central European forests. The species has an especially wide physiological and ecological amplitude enabling growth under various soil conditions within its distribution area in Central Europe. We studied the effects of extreme drought on beech saplings (second year) of four climatically distinct provenances growing on different soils (sandy loam and loamy sand) in a full factorial pot experiment. Foliar δ13C, δ15N, C, and N as well as above‐ and belowground growth parameters served as measures for stress level and plant growth. Low‐quality soil enhanced the effect of drought compared with qualitatively better soil for the above‐ and belowground growth parameters, but foliar δ13C values revealed that plant stress was still remarkable in loamy soil. For beeches of one provenance, negative sandy soil effects were clearly smaller than for the others, whereas for another provenance drought effects in sandy soil were sometimes fatal. Foliar δ15N was correlated with plant size during the experiment. Plasticity of beech provenances in their reaction to drought versus control conditions varied clearly. Although a general trend of declining growth under control or drought conditions in sandy soil was found compared to loamy soil, the magnitude of the effect of soil quality was highly provenance specific. Provenances seemed to show adaptations not only to drought but also to soil quality. Accordingly, scientists should integrate information about climatic pre‐adaptation and soil quality within the home range of populations for species distribution modeling and foresters should evaluate soil quality and climatic parameters when choosing donor populations for reforestation projects.  相似文献   

17.
The tepary bean ( Phaseolus acutifolius Gray var. latifolius ), a drought resistant species, was compared under water stress conditions with the more drought susceptible P. vulgaris L. cvs Pinto and White Half Runner (WHR). In order to better understand the basis for the superior drought resistance of tepary, this study was designed to determine the relationships among leaf water potential, osmotic potential, turgor potential, and relative water content (RWC).
Plants were prestressed by withholding irrigation water. These stress pretreatments changed the relation between leaf water potential and relative water content of both species so that prestressed plants had lower water potentials than controls at the same leaf RWC. Tepary had lower water potentials at given RWC levels than Pinto or WHR; this can account for part of the superior resistance of tepary. In all genotypes, prestressed plants maintained osmotic potentials approximately 0.2 MPa lower than controls. Tepary reached osmotic potentials that were significantly lower (0.15 to 0.25 MPa) than Pinto or WHR. Both control and prestressed tepary plants had 0.05 to 0.25 MPa more turgor than Pinto or WHR at RWC values between 65 and 80%. Both prestressed and control tepary plants had greater elasticity (a lower elastic modulus) than Pinto or WHR. This greater turgor of tepary at low RWC values could be caused by several factors including greater tissue elasticity, active accumulation of solutes, or greater solute concentration.
Tepary had significantly lower osmotic potentials than the P. vulgaris cultivars, but there was little difference in osmotic potential between Pinto and WHR. Knowledge of differences in osmotic and turgor potentials among and within species could be useful in breeding for drought resistance in Phaseolus.  相似文献   

18.
Bryla  David R.  Duniway  John M. 《Plant and Soil》1997,197(1):95-103
The influence of arbuscular mycorrhizal fungi on drought tolerance and recovery was studied in safflower (Carthamus tinctorius L.) and wheat (Triticum aestivum L.). Plants were grown with and without the mycorrhizal fungus, Glomus etunicatum Becker & Gerd., in nutrient-amended soil under environmentally-controlled conditions to yield mycorrhizal and nonmycorrhizal with similar leaf areas, root length densities, dry weights, and adequate tissue phosphorus. When drought stress was induced, mycorrhizal infection did not affect changes in leaf water, osmotic or pressure potentials, or osmotic potentials of leaf tissue rehydrated to full turgor in either safflower or wheat. Furthermore, in safflower, infection had little effect on drought tolerance as indicated by the level of leaf necrosis. Mycorrhizal wheat plants, however, had less necrotic leaf tissue than uninfected plants at moderate levels of drought stress (but not at severe levels) probably due to enhanced phosphorus nutrition. To determine the effects of infection on drought recovery, plants were rewatered at a range of soil water potentials from –1 to –4 MPa. We found that although safflower tended to recover more slowly from drought after rewatering than wheat, mycorrhizal infection did not directly affect drought recovery in either plant species. Daily water use after rewatering was reduced and was correlated to the extent that leaves were damaged by drought stress in both plant species, but was not directly influenced by the mycorrhizal status of the plants.  相似文献   

19.
Goicoechea  N.  Antolín  M.C.  Sánchez-Díaz  M. 《Plant and Soil》1997,192(2):261-268
The objective of this research was to study the effect of drought on nutrient content and leaf water status in alfalfa (Medicago sativa L. cv Aragón) plants inoculated with a mycorrhizal fungus and/or Rhizobium compared with noninoculated ones. The four treatments were: a) plants inoculated with Glomus fasciculatum and Rhizobium meliloti 102 F51 strain, (MR); b) plants inoculated with R. meliloti only (R); c) plants with G. fasciculatum only (M); and d) noninoculated plants (N). Nonmycorrhizal plants were supplemented with phosphorus and nonnodulated ones with nitrogen to achieve similar size and nutrient content in all treatments. Plants were drought stressed using two cycles of moisture stress and recovery. The components of total leaf water potential (osmotic and pressure potentials at full turgor), percentage of apoplastic water volume and the bulk modulus of elasticity of leaf tissue were determined. Macronutrient (N, P, K, Ca, S and Mg) and micronutrient (Co, Mo, Zn, Mn, Cu, Na, Fe and B) content per plant were also measured. Leaves of N and R plants had decreased osmotic potentials and increased pressure potentials at full turgor, with no changes either in the bulk modulus of elasticity or the percentage of apoplastic water upon drought conditions. By contrast, M and MR leaves did not vary in osmotic and turgor potentials under drought stress but had increased apoplastic water volume and cell elasticity (lowering bulk modulus). Drought stress decreased nutrient content of leaves and roots of noninoculated plants. R plants showed a decrease in nutrient content of leaves but maintained some micronutrients in roots. Leaves of M plants were similar in content of nutrients to N plants. However, roots of M and MR plants had significantly lower nutrient content. Results indicate an enhancement of nutrient content in mycorrhizal alfalfa plants during drought that affected leaf water relations during drought stress.  相似文献   

20.
自然状况下头状沙拐枣对水分条件变化的响应   总被引:11,自引:0,他引:11       下载免费PDF全文
 对塔克拉玛干沙漠南缘沙漠-绿洲过渡带前沿人工植被头状沙拐枣(Calligonum caput-medusae)水分关系的研究表明:头状沙拐枣在生长季节中一直保持着正的膨压,水分亏缺的发展并不严重,植被所受水分胁迫在正常范围内,因而在现存条件下干旱引起的水分胁迫不足以威胁植被的存在。在生长进程中,随着环境胁迫的加剧,头状沙拐枣依然维持了比较高的水势和渗透势,实验结果也显示植株体内可溶性物质(NsDM)的累积程度并没有升高,因而其生理过程仍然在比较宽松的环境中进行。相对含水量(RWCp)在生长季节一直保持很高的水平,这对植株保持体内水分防止水分过度损失有利。头状沙拐枣在干旱胁迫下表现出的这些生理特点说明,植物对干旱环境的生理适应类型属于抵抗型。在叶水平上植株对干旱胁迫的水分生理适应主要表现为质外体水比例的增高,细胞壁弹性的增加,持续较高的相对含水量(RWCp)以及灌水后RWCp和枝条水分比值(WCsat)的增加上。夏季的引洪灌溉有助于头状沙拐枣水分状况的恢复,并很可能是植被免于严重水分胁迫的原因之一。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号