关键词: 紫花苜蓿, 紫花苜蓿, 品种, 生产性能, 营养价值, 综合评价

Abstract: As the half arid area, returning farmland to forest and grassland, which is not only the main direction of adjusting the industrial structure, but also is an important work for the building of the ecological environment in Huanxian county. So, climate- studying has important practical significance to Returning farmland effect. This paper adopts research method of the climate tendency coefficient and climatic trend rate, cumulative anomaly, YAMAMOTO test, by analyzing the consecutive meteorological data from 1957 to 2012. The results showed that: over the past 55 years, the annual average temperature increase 0.43 ℃ / 10a, this is much higher than the national average temperature growth which is 0.22 ℃ / 10a .The annual average temperature is even a mutation phenomenon from cold to warm in 1987, before and after the mutation , temperature increased by 1.2 ℃; over the 55 years, it showed a trend of decrease of annual precipitation change, the damping is 15.4 mm / 10 a, annual precipitation days also showed a trend of decrease. Climate is warm and dry, it increases in the heat and light and meanwhile, it also causes droughts, floods, hail, frost and other natural disasters, it has a certain influence on returning farmland to forest and grass work. In order to cope with the effects of climate changes, the author suggested that planting structure should be adjusted in this area from food crops to grass and trees, so that improve the ecological environment. Returning farmland to forest and grassland should take shelter forest and economic forest with arbor, irrigation, grass; The native species of tree and grass with drought resistance and cold resistance should be chosen; Grass and shrubs can be directly seed with the rainy season in the barren hills, wasteland and so on. As arbor can plant by stock in the spring and autumn season ,select multiple strains of afforestation, shade reforestation and other methods of drought resistance afforestation and raise survival rate with temperature raising agent; vigorously develop the " 121" rainwater harvesting, water conservancy, so that keep the trees and grass from the water.