Comparative analysis of the growth among alfalfa varietieswith different fall dormancy rate in Beijing

Studies on the dynamic growth of different alfalfa varieties showed that the order of alfalfa varieties with different fall dormancy rates reached a same growth period was as follows: extreme nondormancy type, nondormancy type, halffall dormancy type and fall dormancy type. In a period of fertility, the dynamic change of alfalfa height was fitted to the Logistic model (r0.954 1). The fastgrowth period of different alfalfa varieties were in branching and heading periods, which accounted for more than 50% of total growth. Gray systematical analysis indicated that under the natural conditions, the alfalfa growth was influenced by the air temperature, illuminating intensity, relative humidity and other climatically factors and the order of influence was as follows: air temperature illuminating intensity relative humidity.