A comparison of photosynthethetic characteristics in four poplar clones

Abstract

The photosynthetic characteristics and the relationship of net photosynthetic rate,water use efficiency with the environmental factors and stomatal conductance in four new poplar clones(3~#、6~#、8~#、9~#) were studied.The results showed that the peak value of the diurnal courses of the photosynthetic rate generally appeared around 10:00,and then reduced gradually.The diurnal courses of transpiration rate in different months were different.The peak value of the diurnal courses of stomatal conductance generally appeared at 7:00~9:00.The total mean net photosynthetic rate(μmol CO_2·m~(-2)·s~(-1)),transpiration rate(mmol H_2O·m~(-2)·s~(-1)) and water use efficiency(mmol CO_2·mol~(-1) H_2O) had following order in June,July and August respectively: Clone 9~#(8.53)6~#(7.21)3~#(6.47)8~#(4.98);Clone 9~#(3.74)3~#(2.76)6~#(1.76)8~#(1.47);Clone 8~#(4.77)6~#(4.35)3~#(2.99)9~#(2.40).Clone 9~# had higher net photosynthetic rate and transpiration rate,with lower water use efficiency.On the contrary,clone 8~# had lower net photosynthetic rate and transpiration rate,with higher water use efficiency.Net photosynthetic rate and water use efficiency had a close relationship with the air temperature and relative humidity in 6~#,and had a close relationship with the photosynthetic active radiation and stomatal conductance in 3~#、8~# and 9~#.