不同土壤水分胁迫下沙漠葳的生长及生物量的分配特征

将从美国西部引进的2年生的沙生灌木沙漠葳（Chilopsis linearis）分别盆栽于含水量不同的土壤中,研究其生长及生物量的分配特征.结果表明,土壤水分胁迫严重限制了沙漠葳的营养生长和生殖生长,使单株叶片数、分枝数和侧根数显著下降,生物量大大降低,其中中度和重度胁迫下沙漠葳的干重分别比轻度胁迫降低40.9%和76.4%.重度土壤水分胁迫下沙漠葳的单叶干重、单叶面积和单位叶面积干重分别比轻度土壤水分胁迫降低63.45%、47.39%和27.23%,比叶面积和根茎比分别上升22.28%和86%.随土壤水分胁迫的加重,光合物质的积累从中下部叶片向中上部叶片转移.各构件生物量随土壤水分胁迫的加重而降低,其幅度大小为叶生物量＞茎生物量＞主根生物量＞侧根生物量,反应了沙漠葳对土壤水分胁迫响应的整体行动.

Growth and biomass allocation of Chilopsis linearis under different soil water stresses

In this paper,2-year old Chilopsis linearis introduced from western USA was pot-cultured under different soil moisture regime,and its growth and biomass allocation were studied.The results showed that soil water stress severely restricted the vegetative and reproductive growth of C.linearis,and induced a remarkable decrease of its individual leaf number,branch number,lateral root number,and total biomass.Compared with light water stress,medium and heavy water stress decreased the individual dry biomass of C.linearis by 40.9% and 76.4%,respectively.Under heavy soil water stress,the single leaf dry biomass,single leaf area,and the ratio of single leaf dry biomass to single leaf area decreased by 63.45%,47.39% and 27.23%,while the ratio of leaf surface area to its fresh biomass and that of root to stem increased by 22.28% and 86%,respectively,compared to light water stress.With aggravating soil water stress,there was a trend that photosynthetic matter accumulated mainly in middle and top leaves of stem,and the decrement of component biomass was in order of leaf>stem>main root>lateral root,which reflected the whole plant action to soil water stress.