title: Can the Responses of Photosynthesis and Stomatal Conductance to Water and Nitrogen Stress Combinations Be Modeled Using a Single Set of Parameters?
abstract: Accurately predicting photosynthesis in response to water and nitrogen stress is the first step toward predicting crop growth, yield and many quality traits under fluctuating environmental conditions. While mechanistic models are capable of predicting photosynthesis under fluctuating environmental conditions, simplifying the parameterization procedure is important toward a wide range of model applications. In this study, the biochemical photosynthesis model of Farquhar, von Caemmerer and Berry (the FvCB model) and the stomatal conductance model of Ball, Woodrow and Berry which was revised by Leuning and Yin (the BWB-Leuning-Yin model) were parameterized forLilium(L. auratum×speciosum"Sorbonne") grown under different water and nitrogen conditions. Linear relationships were found between biochemical parameters of the FvCB model and leaf nitrogen content per unit leaf area (Na), and between mesophyll conductance andNaunder different water and nitrogen conditions. By incorporating theseNa-dependent linear relationships, the FvCB model was able to predict the net photosynthetic rate (An) in response to all water and nitrogen conditions. In contrast, stomatal conductance (gs) can be accurately predicted if parameters in the BWB-Leuning-Yin model were adjusted specifically to water conditions; otherwisegswas underestimated by 9% under well-watered conditions and was overestimated by 13% under water-deficit conditions. However, the 13% overestimation ofgsunder water-deficit conditions led to only 9% overestimation ofAnby the coupled FvCB and BWB-Leuning-Yin model whereas the 9% underestimation ofgsunder well-watered conditions affected little the prediction ofAn. Our results indicate that to accurately predictAnandgsunder different water and nitrogen conditions, only a few parameters in the BWB-Leuning-Yin model need to be adjusted according to water conditions whereas all other parameters are either conservative or can be adjusted according to their linear relationships withNa. Our study exemplifies a simplified procedure of parameterizing the coupled FvCB andgsmodel that is widely used for various modeling purposes.
authors.affiliation: College of Agriculture, Nanjing Agricultural UniversityNanjing, China; Center for Crop Systems Analysis, Department of Plant Sciences, Wageningen University & ResearchWageningen, Netherlands; Horticulture and Product Physiology Group, Department of Plant Sciences, Wageningen University & Research CentreWageningen, Netherlands.
authors.forename: Ningyi
authors.initials: N
authors.lastname: Zhang
authors.affiliation: College of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: College of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Shanxiang
authors.initials: S
authors.lastname: Yu
authors.affiliation: College of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Dongsheng
authors.initials: D
authors.lastname: An
authors.affiliation: College of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Sun
authors.affiliation: College of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Weihong
authors.initials: W
authors.lastname: Luo
authors.affiliation: Center for Crop Systems Analysis, Department of Plant Sciences, Wageningen University & Research Wageningen, Netherlands.
authors.forename: Xinyou
authors.initials: X
authors.lastname: Yin
keywords: mesophyll conductance; model; nitrogen; photosynthesis; stomatal conductance; water