Study On Drought-resistance Of Populus Tomentosa Carr And Populus Deltoides Marshall Clones

11 Populus tomentosa Carr clones and 10 Populus deltoides Marshall clones were used as test materials.The growth indexes,physiological and biochemical indexes of seedling seedling stage under different soil water stress conditions(100% soil moisture content,60% soil moisture content and 30% soil moisture content)were determined by water control treatment with different gradients.The adaptive ability of each clonal system included rhizome ratio,leaf transpiration rate,relative conductivity and the Pro content of leaf.The productivity under drought conditions included the net photosynthetic rate,biomass,plant height,ground diameter and other indexes.We analyzed the correlation between the indexes,and selected suitable indexes to make a comprehensive evaluation of the drought resistance of each clonal system by using TOPSIS method,which provided theoretical basis for the breeding of drought resistant varieties of Populus tomentosa Carr and Populus deltoides Marshall clones.The results of this experimental study showed that:1 11 Populus tomentosa Carr clones Under the condition of water stress,the growth of seedling height and ground diameter was inhibited,and the accumulation of dry biomass in root,stem and leaf was correspondingly decreasing.‘Qinbaiyang1hao’ ‘Qinbaiyang2hao’‘Qinbaiyang3hao’ ‘Qinbaiyang4hao’ ‘Qinbaiyang5hao’ ‘04-14-15’ were larger than the control variety ‘84K’ ‘I-101’ ‘P.tomentosa Carr 30hao’.Under different water stress conditions,the net photosynthetic rate of clones showed a decreasing trend,and the decline of ‘Qinbaiyang1hao’‘Qinbaiyang4hao’ ‘Qinbaiyang5hao’ ‘03-4-22’ ‘04-17-12’and‘07-23-23’ were smaller,showing that those clones had a better drought productivity.The clones of ‘Qinbaiyang1hao’ ‘Qinbaiyang2hao’ 04-17-12’ had the smallest transpiration rate,indicating that these clones had a strong drought-resistance capacity.‘Qinbaiyang1hao’ ‘Qinbaiyang2hao ’ ‘Qinbaiyang3hao’ ‘Qinbaiyang5hao’ ‘04-17-12’relative conductivity changes were small.With the increase of water stress,the Proline content of each clonal leaf increased with different amplitude.2 10 Populus deltoides Marshall clones The effect of drought stress on the growth ofPopulus deltoides Marshall clones was significant,especially in the accumulation of biomass,which indicated that the deficiency of water seriously limited the growth of clones,and showed a significant decrease in plant height and ground diameter compared with CK.‘Qinheiyang1hao’‘Qinheiyang2hao’‘14-Su1’‘14-Su3’‘Tennessee-1’‘Tennessee-2’‘Ten nessee-3’are greater than the control variety ‘Shanlin3hao’ ‘69 Poplar’,and ‘14-Su5’biomass was the smallest.‘Qinheiyang2hao’ and ‘Tennessee-3’ under different treatment,the net photosynthetic rate decreased less and performed better in productivity.Drought stress also showed significant changes in physiological substances,the transpiration rate of leaves decreased,the transpiration rate of ‘Qinheiyang1hao’ ‘Qinheiyang2hao’and ‘14-Su8’was the smallest,indicating that it was resistant to water stress.The relative conductivity of the leaves of St-123 under different drought treatment was the smallest,which indicated that drought stress had the least damage to its cell membranes and showed good drought endurance,and its leaf Pro accumulation increased greatly,was sensitive to the response of drought stress,and accumulated osmotic substances to resist drought.3 Comprehensive judgment of drought resistance The growth and physiological indexes of clones of 11 Populus tomentosa Carr and 10 Populus deltoides Marshall were measured,and the differences and correlations among the indexes were analyzed.The drought Resistance evaluation indexes of 11 Populus tomentosa Carr clones were net photosynthetic rate,single leaf area,seedling height,biomass,osmotic regulation ability and cytoplasmic membrane permeability;the evaluation indexes of 10 Populus deltoides Marshall clones were photosynthetic rate,ground diameter,seedling height,biomass,osmotic regulation ability and cytoplasmic membrane permeability.After experimental study and analysis,the drought resistance of most Populus tomentosa Carr clones clones was stronger than that of the control variety ‘Poplus tomentosa 30hao’,and the drought resistance of most Populus deltoides Marshall clones was stronger than that of the control cultivated varieties ‘Shanlin3hao’ ‘69 Poplar’,which indicated that most of the varieties could adapt to the arid environment in northwest China.At the same time,based on the comprehensive Identification Index,the drought resistance of each clonal system was evaluated synthetically by TOPOSIS,and the preliminary results were as:(1)The Clones‘Qinbaiayng1hao’‘Qinbaiayng3hao’‘Qinbaiyang4hao’ ‘QinBaiyang5hao’ ‘03-4-22’‘04-14-15’ and ‘07-17-18’ had a strong comprehensive drought resistance of 11 Populus tomentosa Carr clones;(2)10 Populus deltoides Marshall clones with strong comprehensive drought resistance were ‘Qinheiyang1hao’ ‘Qinheiyang2hao’ ‘Tennessee-3’‘14-Su8’ and ‘St-123’.