疏叶骆驼刺幼苗根系生态学特性对水分处理的响应

通过人工壕沟挖掘法,对疏叶骆驼刺幼苗在不同水分条件下的根系生态学特性的季节变化进行研究.结果表明:①在土壤水分较好的环境中,疏叶骆驼刺幼苗大量拓展水平根,并产生分蘖植株竞争光照资源;而在土壤水分相对缺乏时垂直根系发达,向深层土壤拓展资源空间.根系形态的可塑性是疏叶骆驼刺幼苗获取水分适应干旱环境的重要策略之一.②根冠比随土壤水分的减少而增加,且在生长季后期这种趋势更加明显,增加根冠比是疏叶骆驼刺幼苗适应干旱的策略之一.③幼苗根系的扎根深度和垂直生长速度随着土壤水分的减少而增加.④根系生物量、根系表面积随土壤深度的增加而减小,并在垂直剖面上呈倒金字塔状分布.根系生物量形成过程符合Logistic"慢-快-慢"的S型生长曲线,总生物量随着土壤干旱程度的增加而降低.

Response of Ecological Properties of Roots of Alhagi sparsifolia SHAP.Seedlings to Different Irrigation Treatments

Seasonal variation of ecological properties of roots of Alhagi sparsifolia SHAP.seedlings under different irrigation treatments is studied by manual digging.Conclusions are as following:(1)In morphological features of roots:If water supply is relatively sufficient,the seedlings grow their horizontal roots and tiller new plants for getting more sunshine;if soil moisture content is limited,the seedlings grow their vertical roots in deeper soil.Such root growth is an important property of A.sparsifolia for adapting arid environment;(2)Root-shoot radio is increased with decreasing soil moisture content,especially at the late stage of growing season.To increase the rootshoot ratio is one of the properties of A.sparsifolia for adapting soil moisture shortage;(3)Growth depth and vertical growth speed of the seedling roots are increased with decreasing soil moisture content under the different irrigation treatments;(4)Biomass and surface area of roots are decreased with increasing soil depth,and they are in an inverse "pyramid" distribution.At the beginning of growth season,more biomass of A.sparsifolia increases in shoots for getting more sunshine,but at the end of growth season,much more biomass increases in roots for the growth next year.The formation process of biomass of roots accords with the Logistic S-shaped growth curve.Total biomass is decreased with increasing drought stress.