Growth model and classification of different alfalfa varieties under irrigation conditions

The growth model for 15 varieties of alfalfa as the first crop in the second year under irrigation conditions was investigated. The results showed that the growth model was consistent with the logistic growth curve. There were obvious differences in the regression models of varieties. Based on these models, the highest potential yield (K), maximum growth speed (Vmax), time of maximum growth (t), turning point of growth speed from slow to fast, and that of fast to slow (t1, t2), the period of vigorous growth (t2-t1), and growth characteristic values (GT) were calculated. The variable t2 can be used as an index to the time to begin harvest with reference to production. Partial correlation analysis showed that the potential yield of alfalfa was determined by the product of days of vigorous growth and maximum growth speed. According to the values, the varieties were clustered into five types. The second classification varieties (Golden Empress, Ameristand 201, Derby, Sandili, Vela, and Rest) are appropriate for local planting with harvest beginning on May 17.