水分胁迫和氮添加对白刺根系形态的调控效应

为筛选出干旱地区唐古特白刺（Nitraria tangutorum）根系生长的最佳氮添加量。以唐古特白刺为试材，在干旱胁迫和水分充足两个水分条件下，分别设置4个氮添加水平（0、6、36、60 mmol·L^-1），研究不同土壤水分和氮处理对唐古特白刺根系形态发育特征的影响。水分充足时，氮浓度越高，对白刺根系的抑制效果越明显。当氮浓度为60 mmol·L^-1时，白刺总根长、表面积、体积、直径和根尖数仅为未施氮处理的55.45%、47.07%、38.63%、79.37%和76.55%。水分胁迫下，白刺总根长、表面积、根尖数均在氮浓度为36 mmol·L^-1时达到最高值，分别为792.13 cm、155.74 cm²、2 370.00 个，较无氮处理增加了31.96%、42.95%和20.84%。水分充足时，氮添加会抑制白刺根系生长发育；水分胁迫下，氮添加会促进白刺根系生长，但并非氮素浓度越高，促进效果越好。水分充足时的白刺根系生长状况始终优于干旱条件下的白刺。

The effects of water stress and nitrogen addition on root morphology of Nitraria tangutorum

In order to study the effects of water stress and nitrogen addition on root morphology of Nitraria tangutorum.the root morphological indexes of Nitraria tangutorum were studied under drought stress and nitrogen addition (0 mmol^.L^-1,6 mmol^.L^-1,36 mmol^.L^-1,60 mmol^.L^-1). When water was sufficient, nitrogen addition could inhibit root growth, and the higher the nitrogen concentration, the more obvious the inhibition effect. When the nitrogen concentration was 60 mmol^.L^-1, the total root length, surface area, volume, diameter and number of root tips were 55.45%, 47.07%, 38.63%, 79.37% and 76.55% respectively of without nitrogen treatment. Under water stress, the total root length, surface area and number of root tips were the highest when nitrogen concentration was 36 mmol^.L^-1, they were 792.13 cm, 155.74 cm² and 2 370.00 respectively, which increased by 31.96%, 42.95% and 20.84% compared with nitrogen free treatment. When water was sufficient, nitrogen addition could inhibit root growth. Under water stress, nitrogen addition could promote root growth, but not the higher the nitrogen concentration, the better the promotion effect. Compared with the same nitrogen concentration under different water conditions, the root growth of Nitraria tangutorum was stronger than that of drought stress.