Effects of Groundwater Mineralization and Groundwater Depth on Eco-Physiological Characteristics of Robinia pseudoacacia L. in the Yellow River Delta, China

Groundwater plays a significant role in influencing the growth and distribution of Robinia pseudoacacia L. plantations, with largest planting area Yellow River Delta, by affecting soil water–salt environment. This study aimed to clarify mechanism groundwater’s influence on R. under different levels groundwater mineralization (GWM) depth (GWD). We simulated GWM 0, 2 4 g L−1, GWD 0.8, 1.3 1.8 m. As increased, relative water content (SRWC) salt (dissolved salt) (SSC) increased; sapling biomass (SB), stem mass (SM), leaf (LM), photosynthesis characteristics (maximum net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), transpiration (E) use efficiency (WUE)) decreased; root (RM), ratio (RMR) root–shoot (RSR) first increased then (SMR) decreased (LMR) increased. SRWC decreased, but SSC SB, RM, RMR, RSR, SM LM SMR LMR decreased. were negatively correlated SB characteristics. was RMR whereas it positively LMR. SMR, The principal component, including characteristics, related growth. second mainly allocation. In conclusion, affected content, which key factors pseudoacacia. Adjustments allocation main adaptive strategies salt, drought, flooding stress.