Analysis Of Growing Dynamic Of Alfalfa Leaves And Affecting Environmental Factors

Alfalfa (Medicago sativa L.) is the deeply-rooted perennial leguminous fodder crop with the longest growing history and largest distributing area in the world, being reputed to the King of fodder crops. However a little literature has been reported on the growing dynamic of alfalfa leaves. The writer conducted the researches on the leaf growing dynamic and affected environmental factors of 7 alfalfa cultivars, including 13Rsupreme, Affimity ,Amerigraze401,Lobo,Ameristand201,Xinjiang broad leaf,and Zhonglan no.1, by means of collecting samples in fields, measuring in laboratory and modelling. Results showed:1. Single-leaf area, compound-leaf area, leaf area index of a single tress and plant height of the 7 alfalfa cultivars increased as their growing courses went forward; the dry leaf weight of the 7 cultivars was positively correlated to single-leaf area, compound-leaf area, leaf area index of a single tress and plant height.2. The growing process of leaf and plant height of the 7 cultivars was accordant to model Logistic. However leaf and plant height were different in average growing speed, maximum growing speed and corresponding growing stages as well as fastest growing period among the cultivars.3. With regard to meteorological factors, the growth of leaf and plant height of the 7 alfalfa cultivars was poorly correlated to mean air temperature, relative air humidity, 0-15cm soil temperature or sunshine hours, with correlation coefficients less than 0.64. Whereas they were well correlated to≥5°C and≥10°C accumulative air temperature, soil temperature at 20cm depth and accumulative sunshine hours, with correlation coefficients more than 0.7. It was validated by stepwise regression analyses that movably accumulative temperature (≥5°C,≥10°C) and accumulative sunshine hours played most important roles in the growth of leaves and pant height of alfalfa.