水分胁迫对不同紫花苜蓿品种幼苗生长特性和根系ABA含量的影响

为探讨水分胁迫对3个紫花苜蓿(Medicago sativa L.)品种的生长特性和根系ABA浓度的影响,在温室可控条件下,采用盆栽停水法设置轻度(停水7d)、中度(停水14d)和重度(停水21d)3个水分胁迫水平,对敖汉、中苜1号和三得利3个紫花苜蓿品种进行处理,并分别测量叶片水势、相对含水量、气孔导度、根系ABA含量、地上生物量、根冠比及Fv/Fm。结果表明:随着水分胁迫程度增加,紫花苜蓿的地上生物量、Fv/Fm、叶水势、叶片相对含水量和气孔导度下降,根冠比和根系ABA含量升高。品种间的地上生物量和根系ABA含量差异显著(P0.05),Fv/Fm和根冠比无显著差异(P0.05);敖汉和三得利的气孔导度和土壤体积含水量呈线性正相关,中苜1号则是二项式相关;3个紫花苜蓿品种的气孔导度与叶水势以及气孔导度与ABA含量皆呈指数相关。3个品种对水分胁迫的响应存在显著差异,中苜1号的抗旱性最强,其地上生物量和根系ABA含量最高,敖汉次之,三得利最弱。

Effects of water stress on the growth characteristics and root ABA content of alfalfa

The aim of this study was to investigate the effects of water stress on growth characteristics and root ABA content in three alfalfa varieties,which were treated by withholding water in pots under controlled conditions.Pot experiments were conducted in the greenhouse to determine the effects of water stress on alfalfa.Water stress was imposed by withholding water 7 d (mild drought),14 d (moderate drought) and 21 d (severe drought).Leaf water potential,relative water content,stomatal conductance,root ABA content,shoot biomass,root/shoot ratio and Fv/Fm were measured.Generally,shoot biomass,Fv/Fm,leaf water potential,RWC and stomatal conductance tended to decrease as water stress increased;On the contrary,ABA content and root/shoot ratio (R/S) tended to increase.The differences of shoot biomass and root ABA content between the varieties were significant (P<0.05),but the difference of Fv/Fm and R/S between the varieties were not significant (P>0.05).In addition,by regression analysis,the linear correlations were found between soil water content and stomatal conductance in Aohan and Sanditi,and binomial correlation in Zhongmu NO.1;Correlation of indices was found between stomatal conductance and water potential,and the same between stomatal and ABA content.The responses of 3 alfalfa varieties to water stress were significantly different.Zhongmu No.1,which presented the highest shoot biomass and root ABA content among the 3 varieties,was most tolerant to drought,followed by Aohan and Sanditi.