Studies on photosynthesis of different poplar strains

A study was conducted to determine the net photosynthetic rate and transpiration rate of 1-year-old seedlings of 13 different poplar strains in the nursery of Tonghua City,Jilin,China.Results show that there are significant differences in net photosynthetic rate between different poplar stains.The net photosynthetic rates of Hybrid 1,Hybrid 2,A5-13,and A5-17 are 15.07%,17.15%,5.25%,and 11.52% higher than that of Populus ussuriensis,respectively.The six well growing stains,Hybrid 1,Hybrid 2,A5-17,Optional(self-selection) 1,A5-13,and Huinan 5 have obvious diurnalvariation in photosynthetic rate.Hybrid 1,Hybrid 2,A5-17,and Optional 1 had two peak values of photosynthetic rate,separately at 10:00 a.m.and 14:00 p.m,while A5-13 and Huinan 5 presented a single peak value of photosynthetic rate,appeared at 14:00p.m.Moreover,the diurnalvariation in transpiration rate of the six poplar strains is basically same,rising from morning to noon,reaching the maximum value at 11:00 a.m.to 13:00 p.m.,and then decreasing rapidly.Compared to the control,A5-13,A5-17,Hybrid 1 and Hybrid 2 have a higher photosynthetic rate and transpiration rate,Huinan 5 has a higher photosynthetic rate and lower transpiration,and Optional 1 has the uniform transpiration rate and lower photosynthetic rate.The net photosynthetic rates of the six strains increased along with the luminous intensity in range of 0～800 μmol·m-2·s-1,basically presenting a positive correlation,and light saturation points appeared at 1 500 μmol·m-2·s1.