A model predicting forage maize growth based on temperature and solar radiation
2002
Takahashi, S. (National Inst. of Livestock and Grassland Science, Tsukuba, Ibaraki (Japan))
A dynamic simulation model to predict growth of forage maize is built on a daily time step. The key factors for growth rate in the model are the weather variables of daily solar radiation and air temperature. The daily photosynthetic rate of the canopy is calculated by the equations, which are formulated by the factors of the two weather variables, of development stage (development index) and of the leaf area index. The photosynthetic product is partitioned into leaves, stems, ears, and root system according to the development index. Each organ is respired depending on the air temperature and the stage of the development index. The parameters of the model were determined by data from the cultivar 'Takanewase', which were grown for four years in northern, central and southern locations in Japan. The output from the model showed good agreement with the data sets that were not used in the parameter determination. The regression coefficient of predicted biomass to the observed biomass through the origin for leaves stems, ears and aboveground total by a single regression are 1.034, 0.951, 0.954, and 0.965, respectively. When the model was applied to the cultivar 'P3715', it was necessary for some parameters to be modified. They were the parameters representing the relationships between temperature and the development index, between partitioning rate of reserves and the development index, and between the specific leaf area index and the development index, and also the parameter of maximum photosynthetic rate. After changing these parameters, there was close agreement between observed and predicted aboveground biomass.
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