水分胁迫及土壤质地对新银合欢幼苗根系生长的影响

Influence of Moisture Stress and Soil Texture to Root Growth of Leucaena Leucocephala Seedlings

新银合欢是生物措施治理泥石流的重要树种,但在金沙江干热河谷的泥石流源区,干旱少雨和土壤砾石含量高已成为新银合欢生长的主要限制因子。为揭示新银合欢幼苗在生境中的抗逆特性,利用盆栽模拟试验,从水分胁迫和土壤质地的角度研究了非生物因素对新银合欢幼苗根系生长的影响,结果表明:对根系生长的影响水分胁迫程度大于土壤质地状况;在相同土壤质地条件下,水分胁迫程度与根系长度、累积表面积及根尖数量均呈负相关;在相同土壤水分条件下,低砾石含量的土壤对根系生长的促进作用总体优于高砾石含量的,但在极端水分条件下这种差异不明显;低砾石组和高砾石组对根系生长构成限制条件的土壤水分含量分别在8.25%、11.46%以下。

Leucaena leucocephala is an important tree species of ecological measures for debris flow control.While in the source area of debris flow in the dry-hot valley of Jinsha River,aridity and high gravel content in soil have become the main limiting factors to the growth of Leucaena leucocephala.The paper studied the influence of non-biological factors to the growth of root system from the point of moisture stress and soil texture by simulation tests of potted plant for revealing the characteristic of anti-adversity of seedlings in habitat.The outcomes show that: a) the influence of moisture stress to root growth is greater than that of soil texture;b) the degree of moisture stress is in negative correlation with the length of root system,accumulated surface area and amount of root tips,under the same conditions of soil texture;c) under the same conditions of soil texture,the soil in low gravel content is better for the growth of root system than that of high gravel content,but the difference is not obvious under the conditions of extreme moisture conditions;d) the limiting conditions of soil moisture content of low-gravel-content group and high-gravel-content group to the root system growth are smaller than 8.25% and 11.46% respectively.