Leaf growth and photosynthesis of Quercus liaotungensis in Dongling Mountain region
东灵山地区辽东栎叶的生长及其光合作用

Leaf length,area and weight were measured for Quercus liaotungensis in different stages of leaf development,and the infra red CO 2 technique was applied to measure the seasonal and diurnal rate of net photosynthesis and dark respiration.Based on the mean rate of leaf growth and net photosynthesis,the tendency of carbon transition was also estimated.The results showed that (1) the accretions of leaf length,area and weight had a common tendency of rapid increase in the early stage of leaf expansion.Leaf length and area reached their maxima in early June,shortly after which leaf dry weight also reached the maximum;(2) The rate of net photosynthesis increased in the early stage,and reached its peak in mid July,subsequently declined;while the rate of dark respiration declined during leaf development except a slight rise before abscission;(3) The "noon rest" of net photosynthesis rate in the diurnal variation might be caused by high temperature or high light intensity;(4) Leaf carbon import was relatively high in the early stage of development,and approximated to zero at the tenth day of leaf expansion.Carbon export reached its maximum in mid July.and subsequently declined.It could be concluded that (5) leaf photosynthesis capacity had a close relation to development stage.