Responses of photosynthetic parameters of Quercus mongolica to soil moisture stresses

The effect of drought on plant photosynthetic parameters has not been quantitatively described in the models of plant photosynthetic mechanism, so the seedlings of Quercus mongolica from Northeast China were used to study the responses of the photosynthetic parameters to soil water stresses. The results showed that the relationship between the maximum net leaf photosynthetic rate (Pmax) of Quercus mongolica and soil moisture could be expressed as a quadratic curve (P < 0.01), and Pmax reached the maximum when soil volume moisture was close to 35.45% of the field water holding capacity. The maximum rate of carboxylation (Vcmax), the maximum potential rate of electron transport (Jmax) and triose phosphate utilization (TPU) rate of Quercus mongolica also had quadratic relationships with soil water content (P < 0.01). Namely, Vcmax, Jmax and TPU had similar response curves to soil water, but had different optimal soil water contents. Based on the temperature and responses of plant photosynthetic parameters to water, this function provides researchers with the parameters and methodology for understanding and simulating the responses of plant photosynthetic parameters to drought stress.