Abstract: The response mechanisms of roots of typical desert plants to precipitation and interspecific relationship are poorly understood. To address these uncertainties,the roots morphological characteristics of Reaumuria soongorica and Salsola passerina growing under mono- and mixed-cultural at six different precipitation levels were measured. The results showed:With the increase of precipitation,the fine root biomass of monocultural,mixed-cultural R. soongorica and monocultural S. passerinaincreased firstly,then decreased and then increased. However,the mixed growth of the two plants increased the proportion of fine root biomass but reduced the proportion of coarse root biomass for S. passerina. In the precipitation range of 150~300 mm,the specific root length and specific surface area of mixed-cultural S. passerina were larger than that of monocultural S. passerina. Under the same precipitation condition,the root to shoot ratio of monocultural R. soongorica was greater than that of mixed-cultural R. soongorica and monocultural S. passerina. In conclusion that the mixed growth favors S.passerina to shape good fine root morphology to adapt to the water change,while R. soongorica has a greater root absorption efficiency when it grows alone.

Key words: Precipitation, Growth pattern, Root morphological characteristics, Reaumuria soongorica, Salsola passerina

摘要： 为揭示典型荒漠植物地下根系对降水变化和种间关系的响应，本研究以红砂（Reaumuria soongorica）和珍珠（Salsola passerina）为材料，通过人工模拟降水变化，测定不同降水量（年降水量50 mm~300 mm，Δ=50）下单生和混生红砂和珍珠的根系形态特征指标。结果表明：随着降水量的增加，单生、混生红砂和单生珍珠的细根生物量均呈现增-减-增的趋势；两种植物混生提高了珍珠细根生物量的比重，降低了粗根生物量的比重；在150~300 mm降水量范围内，混生珍珠细根比根长和比根面积均大于单生珍珠；同一降水量条件下，单生红砂根冠比大于混生红砂和单生珍珠。可见，两种植物混生更有利于珍珠塑造良好的根系形态，且在混生生长时其地下部分主要通过调整细根根系形态来适应水分变化，而红砂在单生生长时其根系对水分养分的吸收效率更强。

关键词: 降水量, 生长方式, 根系形态特征, 红砂, 珍珠