水分胁迫对白三叶水分利用能力的影响

目的]研究不同品种白三叶幼苗在水分胁迫下根系生长与其对土壤水分利用能力之间的关系,以期为该物种的合理利用及工程节水提供科学依据。方法]通过抗旱性能不同的2个品种的栽培对照试验,研究了水分胁迫对白三叶叶片相对含水率、根系分布和土壤水分利用的影响。结果]在水分胁迫发生时,白三叶叶片相对含水率不断下降,甚至干枯或死亡;土壤水分变化还影响到白三叶根系在土壤中的分布情况,使不同层次土壤中的根量发生改变,从而改变了白三叶的吸水状况。不同品种又表现出不同的特性,抗旱性较强的品种通过增加深根数量提高对深层土壤水分的吸收能力显著大于抗旱性较差的品种。结论]不同层次土壤含水量的差异是白三叶不同品种对干旱适应性调节的表现,抗旱性较强的品种在干旱胁迫发生时深根数量增加,吸收土壤深层水分的能力较强,水分利用效率更高,因而能够节约灌溉用水;抗旱性较差的品种深根数量较少,仅能利用表层土壤中的水分,而对土壤深层的水分吸收能力较差,过早表现出了受害症状,对工程节水不利。

Effect of Water Stress on the Water-using Capacity of White Clover

Objective] The scientific basis of the rational use and water conservation of white clover(Trifolium repens) was provided through the study on its root growth of different varieties under the water stress and the relationship between the species and its ability in water-using.Method] The effect of water stress on the content of relative moisture,the distribution of root system and the water-using in soil was studied through the comparison experiment in two varieties with different drought resistance.Results] In the water stress occurring,the content of relative moisture in the leaf of white clover was falling,or even dried up or death.The change of moisture in soil also affected the distribution of root system,resulting in the change in the number of root in the different soil layers,thus the status of its absorbent to water was changed.Also different species showed different characteristics and the variety with drought resistance could improve its absorptive capacity of water from deeper soil through the increment in the number of the root at deeper layer,which ability in the moisture-absorbing was significantly greater than the variety with poor drought resistance.Conclusion] The difference in the contain of moisture in the different layers of soil was the performance of the adaptation of white clover to drought,and the number of the root in the deeper layer of soil was increased for the variety with stronger drought resistance under the drought stress so that it was with the ability in absorbing the moisture from deeper layer’s soil resulting in higher water-using efficiency for the irrigation water-saving.There were few number of root in the deeper layer of soil for the variety with poor drought resistance and only could the water in the surface of soil be used by it but in the deep layer of soil so that the symptom of the drought damage stress might appear much earlier under water stress,which was the disadvantage in the implementation of water-saving engineering.