渭北主要造林树种根系抗旱性研究

采用盆栽试验的方法，研究了不同土壤干旱条件下渭北主要造林树种苗木根系活力的变化。结果表明:在一定的土壤干旱范围内，苗木可以通过提高根系活力来适应逆境。当土壤干旱超过一定的阈值后，树木根系将逐步丧失其活力和功能，最终导致地上部分的枯死。各树种中，山杏根系的抗旱性最强，其次是侧柏、刺槐和油松。苗木根系活力除了受土壤干旱胁迫程度的影响之外，还受到干旱持续时间的影响。当土壤含水量降至40%的田间持水量时，土壤干旱已经对油松的生长构成了威胁，但对山杏、侧柏及刺槐的影响不大。

Studies on Drought Resistance of Root System for Major Tree Species Planted in the Weibei Loess Plateau

Under different conditions of soil moisture, seedling root vigor was studied for major tree species planted in the Weibei Loess Plateau by means of a pot experiment. The results showed that seedling could raise its root vigor against soil drought in some scope. When soil moisture was lower than a limit value, seedling would lose its root vigor gradually, so that the seedling would die. Among the tree species tested, root of Prunus armeniaca var. ansu Maxim showed the biggest drought resistance. Roots of Platycladus orientalis, Robinia pseudoacacia and Pinus tabulaeformis followed it. Root vigor was affected not only by the degree of soil drought but also by the duration of soil moisture. If soil moisture was lower than 40% of soil moisture capacity, growth of P.tabulaeformis would be limited, but it would not happen to Prunus armeniaca var. ansu Maxim,Platycladus orientalis and Robinia pseudoacacia.