| By analyzing the data of leaf area index of maize observed in Xifeng Agro-meteorological Experiment Station,it is found that the changing trend of leaf area index in the growth period of maize is slow increase-rapid increase-slow decrease.The leaf area index of various growth periods is much different among years,which is mainly caused by the differences of environmental factors.There is a close correlation between the change of leaf area index and the precipitation,and the leaf area index is positively related to the accumulated temperature and sunlight hours in three leaves to seven leaves period,but not remarkably related to those in other periods.The yield of maize is remarkably related to the leaf area index in heading and milk mature period.When the leaf area index in heading period is less than 3,the output is low;when it is higher than 4, the output begins to decrease;the ideal range of leaf area index is 34. |