Abstract:

Our objective was to examine the effect of climate factors on alfalfa yield in river valley of Tibet. By using grey relevancy analysis(GRA), the relevancy degree between yield (total fresh yield and yield of each mowing )of 20 alfalfa cultivars and climate factors (including precipitation, sunshine hours, mean temperature, accumulated temperature above 5℃, mean maximum temperature, mean minimum temperature, mean wind speed and relative humidity) in growing season was studied in the river valley of Tibet. Results showed that mean minimum temperature affected the yield of the first mowing mostly, and climate factor affecting regrowth yield was primarily temperature index. Climate factors that affected total fresh yield were precipitation on May, June and July and mean minimum temperature on March, April and May. There were different climate factors affecting total fresh yield and every mowing fresh yield, therefore, corresponding measures should be adopted in practice.

Key words: River valley, Alfalfa, Herbage yield, Climate factors, Relevancy degree

摘要：

为了解西藏高海拔河谷气候对紫花苜蓿(Medicago sativa)生产的影响,以西藏达孜引种栽培的20个紫花苜蓿品种为研究对象,分别以3茬次鲜草量产、总草产量为参考数列,以生长期内的降水量、日照时数、平均气温、≥5℃积温、日均最高气温、日均最低气温、平均风速、相对湿度等为参比数列,应用灰色关联度分析法,对西藏紫花苜蓿草产量与气象因子进行关联度分析。结果表明:日均最低温度对第1茬草产量影响最大;而影响再生草产量的气象因子主要是平均温度即热量指标;影响总草产量的气象因子主要是5-7月的降水量和3-5月的日均最低气温。因此,影响紫花苜蓿总草产量及各茬次草产量的主、次气象因子及其效应都有所差异,生产中可进行相应调整。

关键词: 西藏河谷, 紫花苜蓿, 草产量, 气象因子, 关联度