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.