【摘要】 研究了我国培育的4个杨树杂交品系（中石2号、中潜6号、中嘉8号、中新4号）在我国南方生态条件下净光合速率的日进程和季节变化．结果表明：净光合速率的日变化特点是6、7月份均为单峰，9月份为双峰；季节变化特点是7月份的高峰值除中嘉8号外均比6月份的早4h，而9月份净光合速率明显低于6、7月份的．更多还原

【Abstract】 The four poplar hybrid strains (Zhongshi 2,Zhongqian 6,Zhonjia 8,Zhongxing 4)were cultivated in China. The diurnal trends in net photosynthetic rate (Pn) in the south ofChina were studied. The diurnal variation characteristics are that Pn appears a single peak in June and July,but it appears a double peak in September. The seasonal variations were alsostudied. The peaks of Pn except for Zhongjia 8 in July are earlier 4 h than that in June. Pn inSeptember is apparently lowwer than that in June and July.更多还原