Comparison of light response models of photosynthesis in Populus euphratica Oliv.grown under contrasting groundwater conditions

We measured the light response curves of Populus euphratica grown under contrasting experimental groundwater conditions.We assessed the applicability of the light response models for P.euphratica under different groundwater conditions by comparing fitted photosynthetic characteristic parameters with measured values using four classic models.Results showed that the LSP,P_nmax,and LCP parameters under well-watered conditions were best fit by the modified rectangular hyperbola model,whereas R_d was better estimated by the non-rectangular hyperbola model.For P.euphratica under water deficit conditions,the rectangular hyperbola model exhibited better estimation for R _d and LCP,whereas the modified rectangular hyperbola model was more suitable for estimating P_nmax and LSP.Overall,our results suggest that when considering model choice for estimating the light response parameters of P.euphratica,the modified rectangular hyperbola model and non-rectangular hyperbola model are applicable for plants grown under benign water environments,but the modified rectangular hyperbola model and rectangular hyperbola model are preferable for those under water deficit environments.This study helps clarifying the light response processes of P.euphratica under different moisture conditions and provides a theoretical basis for photosynthetic characteristics.