科尔沁沙地紫花苜蓿的光合日动态

Diurnal dynamics of photosynthetic characteristics of alfalfa on Kerqin sandy land.

利用Li-6400光合测定系统,田间实地测定了紫花苜蓿3个品种(敖汉苜蓿、Range-lander和阿尔冈金)的光合作用日变化特征.结果表明:不同生长年限紫花苜蓿3个品种的净光合速率(Pn)、蒸腾速率(Tr)和水分利用效率(WUE)日变化并不完全呈双峰曲线.其中,敖汉苜蓿和阿尔冈金叶片的Pn和Tr峰值均出现在9:00—11:00,Rangelander在11:00,最低值均出现在7:00和19:00;Rangelander和阿尔冈金叶片的WUE最高值出现在7:00,敖汉苜蓿在9:00,最低值均出现在15:00—17:00.综合分析Pn、Tr和WUE3项指标,2年生苜蓿各项指标最佳,1年生次之,而4年生最差;对Pn和Tr影响最大的环境因子是气温,其次是水分亏缺和空气相对湿度.

By using a Li-6400 portable photosynthesis system, the diurnal dynamics of the photosynthetic characteristics of three alfalfa varieties Medicago sativa L. cv. Aohan, M. sativa L. cv. Rangelander, and M, sativa L. cv. Algonquin were studied. The results showed that for the test alfalfa varieties, the diurnal variation curves of their Pn, Tr, and WUE were not all presented doublepeak. For Aohan and Algonquin, the maximum Pn and T occurred at 9：00-11：00; while for Rangelander, they appeared at 11：00. The minimum P and Tr of the three varieties all appeared at 7：00 and 19：00. The maximum WUE of Rangelander and Algonquin appeared at 7：00 and that of Aohan was at 9：00, and the minimum WUE of the three varieties all appeared at 15：00-17：00. Comprehensive analysis on the photosynthetic performance indices Pn, Tr, and WUE indicated that 2 years old alfalfa was in the best state, followed by 1 year old, and 4 years old. Correlation analysis showed that air temperature （Tr） was the main environmental factor affecting P and Tr, followed by water vapor pressure deficit （VPD） and relative humidity （RH）.