气候因子与苜蓿草产量的苜蓿草产量的灰色关联度分析

利用灰色关联度分析法，分别以紫花苜蓿Medicago sativa全年干草产量、各茬次干草产量作参考数列，以紫花苜蓿生长期内≥5 ℃积温、降水量、日照时间、平均温度、平均最高温度、平均最低温度及相对湿度为参比数列，对旱作条件下紫花苜蓿干草产量与气候因子的关联程度作相关分析。结果表明：第1茬草产量与5月上旬、4月上旬、4月中旬的降水量和3月上旬、3月下旬、5月上旬的≥5 ℃积温关联度最大；影响再生草产量的气候因子主要是热量指标；影响全年产草量的气候因子主要是6-8月的最高温度和最低温度，以及4、5、6月的降水量。因此，影响紫花苜蓿全年及各茬草产量的主、次气象因子及其时段效应都是有差异的，生产上应采取相应的措施。

Grey connection analysis of alfalfa yield and climate factors

By using grey connection analysis, the connection degree between alfalfa yield (all year yield and each stubble yield) and climate factors (including accumulated temperature above 5 ℃, precipitation, sunshine hours, mean temperature, mean maximum temperature, mean minimum temperature and relative humidity) was studied in the rain fed farming area. Results were as follows: association degree of yield of the first stubble with precipitation was the biggest, which was in the first ten day of May, the first and middle ten days of April, with effective accumulated temperature above 5 ℃ was the bigger, which was in the first and last ten days of March, and the first ten day of May; Climate factors of affecting on regrowth hay yield were primarily temperature index; Climate factors of affecting on total year hay yield was maximum temperature and minimum temperature most, which was in June, July and August, and precipitation, which was in April, May and June. Primary and lesser climate factors affecting on total year hay yield and every cutting hay yield, and effect of time period were different, therefore, corresponding measures were adopted in practice.