Characteristics And Quantitative Simulation Of Stomatal Conductance Of Panax Notoginseng

In order to construct a mathematical model for response of stomatal conductance (gs) of Panax notoginseng (Burk.) F.H. Chen leaves to environmental factors. Three-year-old P. notoginseng seedlings were used as experimental materials. The daily variation of gs and environmental factors of P. notoginseng leaves in sunny and cloudy days was determined by LiCOR-6400 Infra-Red Gas Analyzer (IRGA) in September and October 2018. The stepwise regression method was used to analyze the response of gs of P. notoginseng leaves to environmental factors, and the optimal gs model of P. notoginseng leaves were simulated and verified by using two types of representative stomatal conductance models. The results showed that the daily variation of gs showed a double-peak curve in sunny days, while in cloudy days showed a single-peak curve. Photosynthetically active radiation (PAR), vapor pressure deficit (VPD) and air temperature (T-air) were the main environmental factors affecting gs, in which PAR and T-air were positively correlated with gs, while VPD was negatively correlated. The best fitting effect of gs of P. notoginseng leaves was Jarvis model 1, followed by Jarvis model 2 and Ball-Berry model 2, and finally Ball-Berry model 1. The fitting effect of each model in the afternoon was better than that in the morning. Therefore, the optimal response model of gs of P. notoginseng leaves to environmental factors was established, which was: g(s)=200.12PAR(1-0.312VPD)(1.347-0.086T+0.002T(2))(1-0.002C(a))/(121.36 + PAR)(1+12.75VPD). This model not only helped to further estimate leaf photosynthesis, but also laid the foundation for simulating water and heat exchange in the soil-plant-atmosphere systems. (C) 2019 Friends Science Publishers