侧柏种基盘苗和营养钵苗移栽后根系生长对不同水分亏缺的响应

苗期干旱胁迫是关系干旱区植被恢复成败的关键制约因子.采用侧柏种基盘育苗和营养钵育苗的方法培育侧柏幼苗,栽植在人工控制环境下,进行重度水分胁迫、轻度水分胁迫和充足水分供应3种水分处理实验,探讨不同类型苗木根系发育对水分亏缺的响应.结果表明：1）在不同水分亏缺条件下,侧柏种基盘苗主根长、根总长、根表面积等均大于营养钵苗,但其根尖数和一级侧根数量在水分供应充足时却小于营养钵苗;2）随着水分胁迫的加剧,种基盘苗主根长不断增加,而总根长则急剧降低;3）无论是种基盘苗还是营养钵苗,苗木的地径和根系生物量都有随水分亏缺程度增加而减小的趋势,但种基盘苗的根冠比却随着水分亏缺程度的加剧而增加;4）在水分胁迫条件下,种基盘育苗比营养钵育苗更能促进苗木的生长.

Responses of root development after transplanting of seed-base and container seedlings of Platycladus orientalis under different water stresses

The water stress happening in seedling period is a key factor inhibiting the revegetation in arid regions. In order to explore the responses of different stoke types to water stress, we transplanted seed- base seedling （SS） and container seedling （CS） of Platycladus orientalis in water controlled condition. Soil water was controlled at three levels： well watered （WW） , mild water stress （MWS） and severe water stress （SWS）. The results showed that SS of P. orientalis had greater taproot length, root length and root surface area, but smaller number of root tips and first order lateral roots than CS. Taproot length increased with the water stress getting more severe; however, total root length decreased rapidly. For both SS and CS, their diameter at ground level and root biomass decreased as the water stress intensified, but the root-to-shoot ratio of SS increased. These results may indicate that SS outperforms CS after transplantation under water stress condition.