Comparative study on light response and CO₂ response of Populus euphratica seedlings under different regeneration methods

To select a suitable regeneration method to rejuvenate the Populus euphratica forest in the lower reaches of the Tarim River, the changes in photosynthesis parameters of Populus euphratica at different seedling ages during the fast-growing period (June-July-August) under artificial digging and natural seeding regeneration methods were analyzed. The photosynthesis-light and CO₂ responses of Populus euphratica seedlings at 2a, 3a, 5a and 7a during the fast-growing period were measured using a US Li-6400XT photosynthesis instrument. The results show that the photosynthetic potential of Populus euphratica seedlings under artificial pit regeneration is better, especially the ability to use strong light, which reflects faster growth under strong light; The A_max value of Populus euphratica seedlings under artificial pit regeneration is generally higher, and the Rubisco activity, CO₂ assimilation capacity, utilization efficiency, and photorespiration rate of Populus euphratica are higher in artificial seed regeneration too. It is concluded that artificial pit regeneration are more suitable, which will help the Populus euphratica forest in the middle and lower reaches of the Tarim River and the demonstration and popularization of planting techniques in future.