应用气象学报 (May 2020)
Construction of the Model for Soil Moisture Effects on Leaf Photosynthesis Rate of Winter Wheat
Abstract
The rate of leaf photosynthesis, which is sensitive to soil moisture, is one of the most important parameters to characterize the photosynthetic capacity of plants. Constructing a model which can reveal effects of soil moisture on leaf photosynthesis rate of winter wheat will be helpful to accurately understand the photosynthesis and yield formation. A total of 310 photosynthesis rate samples under different soil moistures, including 227 drought stress samples in 50 tests and 83 waterlogging stress samples in 14 tests, are jointly collected from 17 winter wheat cultivars at 11 experimental sites via the published references. However, photosynthesis rates of winter wheat are quite different between different cultivars, different developmental stages, and different experimental sites. Normalized photosynthesis rate coefficients for winter wheat are derived by calculating the ratio of leaf photosynthesis rate under different water stresses and CK. And then, segmental and exponential models are established for effects of drought and waterlogging stresses on leaf photosynthesis rate of winter wheat, respectively. The model for soil moisture effects on leaf photosynthesis rate of winter wheat (SMEP) is correspondingly constructed. Photosynthesis rate coefficients of winter wheat leaves show the trend of "stable low value-linear increase-stable high value-slow decrease" with the increase of soil relative moisture. Meanwhile, photosynthesis rate coefficients exhibit characteristics of "slow decline-rapid decline" with the prolongation of waterlogging stress. Four tests, including back-training test, extrapolation test, single-site test and certain developmental stage test, are also done to validate the SMEP model. Generally, the results simulated by the SMEP model are in good agreement with the records in the literatures. The linear regression coefficients are all around 1.0, and the regression equations all pass the significant test of 0.01. SMEP model will be coupled to Chinese Agro-Meteorological Model (CAMM1.0), providing scientific and technological supports for the continuous improvement of CAMM1.0.
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