柳枝稷的生长发育与土壤水分特征

1992-1998年中国科学院安塞水土保持综合试验站在山地、川地引种10份原产美国的柳枝稷（Panicum virgatum）材料，经过7a测定，数据表明柳枝稷在3～5a生长高峰期对土壤水分需求最大，产量最高。从土壤水分含量的变化来看，柳枝稷草地在80-200cm土层已经形成土壤干层，而且在经过生长季节降雨和休闲期的雨雪水分补充不能够补偿，这主要是维持较大的生产力造成。柳枝稷在半干旱黄土丘陵区有较强的适应性，这对当地人工草地建造、天然草地改良具有重要意义。通过对柳枝稷驯化栽培的人工草地在黄土丘陵半干旱地区立地条件下生产力与土壤水分特征的比较，以揭示柳枝稷的生态适应性对其地上生物量形成规律的影响，为该地区合理利用牧草资源、提高草地的生产能力提供依据与参考。

Growth of Panicum Virgatum and Soil Moisture Characteristics

Ten kinds of Panicum virgatum originated in USA were introduced on hill slope and valley plain in the Ansai research station from 1992 to 1998.The data observed for 7 years illustrate that Panicum virga-turn in 3 to 5 year growth fastigium stage particularly requires soil moisture and gives the highest yield. In view of the change in soil water content, Panicum virgatum helps form a dried layer between 80 and 200 cm from soil surface and it can not be compensated by rainfall in growing season, as well as rainfall and snow in leisure time.The problem is resulted from the maintenance for a higher productivity.Panicum virgatum has a strong adaptability in semi-arid hilly and gully region of the Loess Plateau, which is of importance to artifi-cial grassland construction and natural grassland improvement.Through comparing the productivity of Pani-cum virgatum cultivated in the region with the characteristics of soil moisture, the effects of Panicum virga-tum's eco-adaptability on its aboveground biomass formation may be understood.The results offer a scientific basis and an important reference to rational utilization of local herb resources and improvement of grassland productivity.