4种沙生灌木幼苗PV曲线水分参数对干旱胁迫的响应

The Response of Pressure-volume Curve Water Parameters of Four Desert Shurb Seedlings to Drought Stress

以柠条、沙木蓼、杨柴和花棒4种沙生灌木幼苗为材料,采用盆栽法在适宜水分、中度干旱和重度干旱(田间持水量的75%、50%和35%)3种土壤水分条件下,应用PV技术测定了它们在膨压为0时的渗透势(ψstlp)、相对水含量(RWCtlp)和相对渗透水含量(ROWCtlp),以及饱和含水时的渗透势(ψssat)、束缚水含量(Va)、膨压随叶水势下降而降低的速率b值和组织细胞总体弹性模量(ε′)等水分参数,并用隶属函数值法对4种苗木在干旱下保持膨压的能力进行了综合评价.结果显示:与适宜水分条件下相比较,除花棒幼苗在中度及重度干旱下ψssat值、柠条苗在中度干旱下ψssat和ψstlp差值和在中度及重度干旱下Va值、沙木蓼苗在中度干旱下ε′和RWCtlp值均变化很小以外,4种苗木其它水分参数在不同程度干旱胁迫下均有较明显的变化,且其变化幅度随干旱胁迫的加剧而增加,从而使苗木保持膨压及吸水保水的能力较适宜水分下明显增强;苗木保持膨压能力的综合评价结果为:中度干旱下柠条>花棒>杨柴>沙木蓼,重度干旱下柠条>花棒>沙木蓼>杨柴.研究表明,柠条幼苗对干旱胁迫具有极强的渗透调节适应性.

With pressure-volume technique the water parameters including osmotic potential at zero turgor point（ψs^tlp） ,osmotic potential at water saturation point （ψs^sat） ,relative water content and osmotic potential water content at zero turgor point（RWC^tlp and ROWC^tlp） ,rate of bound water（Va）,ratio of descendent of turgor with the leaf water potential （b） and cell whole elastic modulug（ε＇） of seedlings of Caragana korshinskii ,Atraphaxis bracteata , Hedysarum mongolicum , Hedysarum scoparium were studied under three soil moisture treatments which were suitable soil moisture,mediun drought and severe drought（75% ,50% and 35% of saturated soil moisture content）by planting seedlings in pots. The subordinate function value analysis was used to estimate the abilities of maintaining turgor of four species seedlings under drought. Except that the ψs^sat values of Hedysarum scoparium seedlings under medium and severe drought,the differences between ψs^sat and ψ s^tlp and Va values of Caragana korshinskii seedlings under medium drought and under medium and severe drought,the ε＇ and RWC^tlp values of Atraphaxis bracteata seedlings under medium drought changed a little compared with suitable soil moisture. The other water parameters of four speeies seedlings under different drought stress conditions changed considerably and the changes increased along with drought stress becoming stronger. It indicated the abilities of maintaining turgot and capturing and keeping water of seedling were improved obviously compared with suitable soil moisture. The eompre-hensive estimating results on abilities of maintaining turgor showed that they were Caragana korshinskii Hedysarum scoparium〉 Hedysarum mongolicum 〉Atraphaxis bracteata under medium drought and Ca-ragana korshinskii 〉 Hed ysarum scoparium 〉Atra phaxis bracteata 〉 Hed ysarum mongolicum under severe drought. The conclusion was the Caragana korshinskii seedling possess very strong adaptability of osmotic adjustment to drought stress.