霸王和木本猪毛菜在遮风和不遮风环境下的表型特征差异

植物的表型特征是对环境适应的结果。霸王(Zygophyllum xanthoxylum)和木本猪毛菜(Salsola arbuscula)是新疆达坂城大风区的主要植物,也是该区植被恢复潜在的先锋植物。在达坂城柴窝堡,通过野外盆栽实验,对霸王和木本猪毛菜持续吹风和遮风处理90 d,定量分析这两种植物在遮风和不遮风环境下其地上部分的生长和空间构型差异。结果表明:(1)与遮风下的相比,自然大风中的霸王和木本猪毛菜其株高、叶长度、单叶面积、单株叶面积均减小,顺风向基径均增大,尤其是霸王,其株高减小了一半多。木本猪毛菜的叶片数量增多,叶宽增大,霸王的叶片数量减少、叶宽度、叶柄长度、叶柄直径均减小;(2)遮风下的木本猪毛菜其植冠在四个方向均匀生长,而自然大风中的植冠空间构型在迎风面和背风面出现明显的不对称,一级分枝数增多,主茎弯曲角度、枝倾角、叶倾角均减小。霸王没有出现一级分枝,主茎弯曲角度减小,叶倾角增大。可见,霸王主要通过减小地上部分各器官来响应大风环境,而木本猪毛菜除减小各器官之外,还减小各器官之间的角度,形成更紧凑的构型,以此适应大风环境。

Phenotype differences between Zygophyllum xanthoxylum and Salsola arbuscula from open and wind-protected sites

Wind is an important ecological factor. Plants can capture enough light and resist the external mechanical pressure by regulating the phenotype. The study area, Dabancheng in Xinjiang China is basically characterized by strong wind and drought. Salsola arbuscula and Zygophyllum xanthoxylum are dominant shrubs in this area. However, their resistance capacity to wind has not been assessed. This study investigated the phenotype of S.arbuscula and Z.xanthoxylum under strong wind to understand how these two shrubs responds to wind disturbance. Two natural wind regimes (from open and wind protected sites) were designed, lasting for 90 days. In the wind-exposed site, the height of S.arbuscula and Z. xanthoxylum were reduced, the basal stem diameter were increased respectively, compared from the closed site. The height of Z. xanthoxylum were reduced more than half in particular. The leaves of S.arbuscula and Z.xanthoxylum from the open site were smaller in every measured respect than those sampled from the closed site on average. The length and area of the S.arbuscula and Z.xanthoxylum leaves from open site were reduced respectively. The number and diameter of S.arbuscula leaves from wind-exposed site were increased, but the number and width of Z.xanthoxylum leaf from open site were decreased, the length and diameter of Z.xanthoxylum petiole from open site were reduced respectively, compared from the wind-protected site. S.arbuscula showed asymmetrical canopy in the wind-exposed site, number of the first order branch was increased with wind loading. Compared from the wind-protected site, the trunk angle to horizon, branch and leaf angle to trunk of S.arbuscula were reduced respectively. Z. xanthoxylum from the open site did not have the first order branch, its trunk angle to horizon was reduced, while leaf angle to trunk was increased, compared from the wind-protected site. It is indicated that S. arbuscula and Z. xanthoxylum exhibit dwarfism in response to chronic strong wind disturbance, and S. arbuscula also show a more compact form, with increased stem taper and smaller angle between branch and leaf,which present a streamlined shape to adapt the prevailing wind.