Study On Clonal Propagation And Drought Resistance Of Elite Populus Purdomii In Qinghai Province

In this experiment,the survival rate and growth of 1 year old seedlings of 48 clone cuttings selected from Mutual Aid Beishan Forest Region in 2008,14 clone cuttings selected from Maixiu Forest Region,Shuangpengxi Forest Region,Lancai Forest Region,Mengda Nature Reserve of Xunhua,Qilian Forest Region of Qilian County,Gucheng and Liancheng Forest Region of Gansu Province in 2015,and 13 clone cuttings selected from Mutual Aid Beishan Forest Region in 2015 were compared in the nursery of Mutual Aid Beishan Forest Farm.And then six excellent clones H1,H10,HB10,HB18,HB19 and M2 were screened for stomatal and physiological indexes determination.There was a negative correlation between stomatal density and stomatal length of Populus purdomii,and it was related to water use efficiency.There were obvious differences in the physiological indexes of six groups of Populus purdomii under drought stress,and the physiological responses to drought stress were different,which indicated that there was a one-sidedness in the evaluation of drought tolerance among six groups of Populus purdomii by single physiological index.Therefore,only single physiological index can not accurately reflect the drought resistance of six groups of Populus purdomii.By using the mathematical models of net photosynthetic rate and soil moisture content of H1,H10,HB10,HB18,HB19,M2,the soil hydration compensation points of H1,H10,HB10,HB18,HB19 and M2 were calculated at 1.19%,5.02%,2.05%,2.19%,2.10% and 1.34% respectively.And the appropriate soil water content of H1,H10,HB10,HB18,HB19 and M2 was 11.18%-15.34%,21.61%-29.66%,26.41%-36.25%,22.34%-30.65%,23.87%-32.75%,17.54%-24.07% respectively.Then,based on the changes of Pn,Tr,PPO,CAT activities of the six-group Populus purdomii leaves,the drought resistance of six groups of Populus purdomii were evaluated by membership function method,and the average membership function values of four physiology indicators of the leaves of H1,H10,HB10,HB18,HB19,HB19 and M2 were 0.528,0.475,0.492,0.439,0.474,0.505,respectively.Thus,the order of drought resistance of six groups was H1 > M2 > HB10 > H10 > HB19 > HB18.In addition,the growth characteristics of H1,H10,HB10,HB18,HB19 and M2 under normal conditions were evaluated by fuzzy membership function method,and the average membership function values of 11 indexes of H1,H10,HB10,HB18,HB19,M2 were 0.025,0.018,0.026,0.078,0.029,0.030,respectively.Therefore,the growth traits of H1,H10,HB10,HB18,HB19 and M2 were HB18 > M2 > HB19 > HB10 > H1 > H10.