Effects Of Seedling Regeneration On Physiological And Ecological Characteristics Of Populus Euphratica At Different Seedling Ages

Populus euphratica seedlings grow slowly in the middle and lower reaches of the Tarim River.In order to enrich the resources of Populus euphratica in the Tarim River,improve the quality of artificial regeneration of Populus euphratica,and promote the growth,survival and breeding of Populus euphratica in the Tarim River,This paper attempts to compare and analyze the seedlings of Populus euphratica at different seedling ages under artificial digging and natural seedling drop regeneration methods.In order to solve the problems of delayed regeneration,degradation,ecological instability and desertification of Populus euphratica in the middle and lower reaches of the Tarim River,we should choose the appropriate age of transplanted Populus euphratica seedlings and appropriate regeneration methods.improve the research content of artificial regeneration of Populus euphratica,and demonstrate and popularize the technology of seedling regeneration of Populus euphratica.By studying the physiological and ecological responses of Populus euphratica seedlings of different seedling ages under different renewal modes,we can better judge the adaptability of selecting renewal modes and transplanting Populus euphratica seedlings.From June to July to August in 2018,Populus euphratica seedlings of different seedling ages were regenerated by artificial digging and natural seedling dropping.valuated comprehensively,which determined by the photosynthetic index,growth index The research results showed that:（1）There are significant differences in photosynthetic physiological parameters of Populus euphratica seedlings of different seedling ages under different regeneration modes,The photosynthetic physiological parameters of Populus euphratica seedlings at different seedling ages were different under two renewal modes,artificial digging and natural dropping.Under the two renewal modes,5-year and 7-year-old Populus euphratica seedlings had strong photosynthetic capacity and high water use efficiency.The total photosynthetic rate of Populus euphratica seedlings under artificial digging Populus euphratica seedlings regenerated by natural seeding and digging.G_sand PAR promoted P_nof Populus euphratica seedlings under two renewal modes,while WUE and T_linhibited P_nof Populus euphratica seedlings under two renewal modes.（2）Using the right-angle hyperbolic correction model to fit the light response parameters.The photosynthetic potential of 5-year-old seedlings（June）/2-year-old seedlings（June）was the highest under the two renewal modes of artificial digging and natural dropping;the photosynthetic efficiency of 5-year-old seedlings（June）and3-year-old seedlings（July）was higher under the two renewal modes,and the photosynthetic efficiency of 7-year-old seedlings remained at a better level under the two renewal modes;the artificial digging and natural dropping were the two renewal modes.7-year-old seedlings and 5-year-old seedlings had better light-lowering ability,and 3-year-old seedlings（August）consumed more organic matter.（3）Using the right-angle hyperbolic correction model to fit the CO₂response parameters.A_maxof 5-year-old seedlings（August）/7-year-old seedlings（August）was the largest under the two renewal modes of artificial digging and natural drop,and the overall photosynthetic capacity of Populus euphratica seedlings was better under the artificial digging renewal mode;the average carboxylation efficiency was the highest for 2-year-old seedlings/7-year-old seedlings,respectively;the photosynthesis of2-year-old seedlings（June）under the artificial digging renewal mode was the highest,and under the artificial digging renewal The photorespiration rate of poplar seedlings was higher than that of natural seedlings.（4）The growth characteristics of Populus euphratica seedlings of different seedling ages under two renewal modeswere significantly different,The rapid growth period of Populus euphratica seedlings at different seedling ages was mainly from July to the end of August under artificial digging and natural seeding.The growth increments of Populus euphratica seedlings at different growth stages were also different.The 3-year-old seedlings height and ground diameter growth increments were the largest under artificial digging.（5）According to the clustering result of the comprehensive evaluation of Populus euphratica seedlings adapation,the two Populus euphratica seedlings with excellent adaptability of 5-year-old seedlings 7-year-old seedlings were selected and suited promotion.The artificial digging is better than natural seedling dropping.Provide scientific basis for demonstration and extension of seedling regeneration technology of Populus euphratica in the middle and lower reaches of Tarim River.In summary,5-year-old and 7-year-old seedlings have good adaptability and are suitable for transplantation.Artificial digging and regeneration methods are selected for Populus euphratica seedling cultivation and growth.