水分胁迫对紫花苜蓿叶片水势及生物量分配的影响

Effects of water stress on leaf water potential and biomass allocation of Medicago sativa

摘要:

为探讨水分胁迫对新疆大叶苜蓿叶水势与生物量的影响及其相关性。本研究采用盆栽控水法，以 1 年生新疆大叶苜蓿为试验材料，设置充分供水(T1)、轻度胁迫(T2)、重度胁迫(T3)3 个水分梯度，研究不同水分胁迫下新疆大叶苜蓿在不同生育时期的叶水势、苗高、根径、根长、根干重、茎干重和叶干重的变化。结果表明：新疆大叶苜蓿的叶水势在整个生育期内均呈现 T1＞T2＞T3 的规律，且 T3 与 T1 和 T2 之间均有显著性差异(P＜0. 05)；轻度水分胁迫会刺激新疆大叶苜蓿的苗高、根径和根长的生长，在整个生育期内均表现为 T2＞T1＞T3 的规律；轻度水分胁迫时，新疆大叶苜蓿在整个生长阶段茎干重显著高于充分供水和重度水分胁迫，其根干重在苗期和分枝期呈现为 T2＞T1＞T3，现蕾期和开花期表现为 T3＞T2＞T1 的规律；叶干重除苗期外，在分枝期、现蕾期和开花期均表现为 T2＞ T1＞T3。该结果为干旱、半干旱地区苜蓿节水栽培和作物高效用水机制提供理论依据。

Abstract:

In order to explore the effect of water stress on the leaf water potential and biomass of Medicago sa- tiva cv. Xinjiangdaye and its correlation，pot water control method was used to study the changes of leaf water poten- tial，seedling height，root diameter，root length，root dry weight，stem dry weight and leaf dry weight of one-year-old Medicago sativa cv. Xinjiangdaye in different growth periods under different water stress by setting three water gradi- ents： full water supply （T1），mild stress （T2） and severe stress （T3）. The results showed as follows： the leaf water potential of Medicago sativa cv. Xinjiangdaye presented the rule of T1>T2>T3 during the whole growth period， and there were significant differences between T3，T1 and T2（P<0. 05）. Mild water stress would stimulate the growth of seedling height，root diameter and root length of Medicago sativa cv. Xinjiangdaye，which showed the law of T2>T1>T3 throughout the growth period. Under mild water stress，the stem weight of Medicago sativa cv. Xin-jiangdaye was significantly higher than those of Medicago sativa cv. Xinjiangdaye under adequate water supply and se- vere water stress during the whole growth stage. In the mean time，under mild water stress，the root dry weight showed the order of T2>T1>T3 at seedling stage and branching stage，and T3>T2>T1 at bud stage and flower- ing stage. Except seedling stage，the leaf dry weight showed T2>T1>T3 at branching stage，bud stage and flower- ing stage. The experimental results provide a theoretical basis for alfalfa water-saving cultivation and crops water-effi- cient mechanism in arid and semi-arid areas.