Studies on the Leaf Photosynthetic Characteristics of Summer-sown Corn during the Course of the Growth and Development

The leaf photosynthetic characteristics of 5 corn hybrids were studied.The results showed that the pattern of the course of dynamic changes of the chlorophyll content and the soluble protein content of leaves at different positions were approximately the same,their maximum values appeared after the leaves full expansion,then gradually decreased when the leaves were getting old,but the photosynthetic rates of leaves at different positions reached the maximum values at leaves full expansion.During the last phase of growth and development of the corn plant,the soluble protein content of the 15th leaf and the photosynthetic rates of the 18th leaf were higher than others.