Modelling growth processes of selected indica rice varieties grown under different nitrogen levels
1996
Sta Cruz, P.C. | Garcia, F.D. | Yajima, M. | Yoshida, K. | Takahashi, H. (Philippine Rice Research Inst., Maligaya, Munoz 3119, Nueva Ecija (Philippines))
The evaluation of the Developmental Stage (DVS) model showed that it can estimate the heading dates of rice genotypes from Tsukuba and Munoz sites, provided that DVS parameters used are taken from both sites. A growth model in combination with the DVS model was developed. An added feature of the new model is its capability to predict leaf area index (LAI) and dry matter accumulation (DMA) under varying nitrogen (N) applications. The parameters used in the growth model were generated from two separate experiments conducted at Tsukuba and Munoz sites from 1993 to 1994. The estimated LAI and top dry matter values using the new mode matched the actual values obtained at both sites. In some N application, however, the model overestimated the DMA particularly at the middle and late stages of plant growth. This was attributed to the disfunction between the radiation - use efficiency values used in the model and the actual N economy of the plant. Hence, a third experiment was conducted in 1995 at Munoz site to establish stable growth parameters under varying N levels. The modified varietal coefficient produced good fit between actual and estimated LAI and DMA values. Field experiments at Tohoku and Munoz sites are being conducted to generate yield index and grain filling parameters for the model to be utilized in yield forecasting
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