沙打旺与柳枝稷单、混播种苗期水分利用和根冠生长的比较

在室内生长箱内盆栽沙打旺和柳枝稷的苗期生长阶段进行高土壤水分 (黄绵土土壤田间持水量FC的 80 % )和低土壤水分 (5 0 ?)处理 ,比较二者单、混播种植下水分利用与根冠生长差异 ,以探讨黄土高原半干旱丘陵区牧草植物的合理种植方式 .结果表明 :在水分利用方面 ,低水处理下混播使沙打旺和柳枝稷叶片瞬时水分利用效率均较单播提高 ,低水处理后混播群体水分利用效率也显著比单播柳枝稷增大 .在根冠生长方面 ,混播促进了柳枝稷地上部分植株高度生长 ,并使地下部分分配比重增大 ,根系绝对长度缩短 ;混播后沙打旺的植株高度降低 ,根系绝对长度增加 ,但干物质分配比重减小 .低水处理后 ,沙打旺和柳枝稷混播下的根冠生长趋向于资源的充分合理利用 ,表现在混播群体的根系生长有利于充分利用土壤深层水和表层来水 ,混播后地上部分高度的生长特征变化利于对光的利用 .因此 ,在水分和养分条件相对较差坡地占较大比例的半干旱黄土丘陵地区 ,采用沙打旺和柳枝稷混播种植相比各自单播利于促进苗期生长与提高土壤水分利用率 .图 2表 2参 10

COMPARATIVE STUDY OF WATER USE EFFICIENCY AND GROWTH OF ASTRAGALUS ADSURGENS AND PANICUM VIRGATUM SEEDLINGS UNDER SEPARATED AND MIXED PLANTATION

In this study, Astragalus adsurgens and switchgrass (Panicum virgatum) under separated and mixed plantation in pots were treated with two levels of soil water supplies: high (80% field capacity of loess soil water holding, the soil moisture content: 14.72%) and low (50?, the soil moisture content: 9.2%) at seedling stage in growth chamber. The results through comparing the leaf gas exchange, plant shoot and root growth and water use efficiency showed that: mixed plantation could improve A. adsurgens and switchgrass leaf water use efficiency and mixed community water use efficiency, especially under low soil water supply. Plant height of switchgrass increased faster when mixed with A. adsurgens, and the root length decreased but the root biomass/shoot biomass increased as compared with separated plantation, those of A. adsurgens under mixed plantation with switchgrass changed on the opposition entirely as compared with switchgrass. So the A. adsurgens and switchgrass roots and shoots growth of A. adsurgens and switchgrass inclined to use resources effectively in mixed plantation under low soil moisture treatment. It was proposed that the switchgrss switchgrass and A. adsurgens could be mixed planted to improve soil water use efficiency and facilitate seedling growth at slope land in semi-arid loess hilly gully region. Fig 2, Tab 2, Ref 10