Main content area

A process model for explaining genotypic and environmental variation in growth and yield of rice based on measured plant N accumulation

Yoshida, Hiroe, Horie, Takeshi
Field crops research 2009 v.113 no.3 pp. 227-237
Oryza sativa, rice, plant growth, grain yield, nitrogen, plant nutrition, nutrient uptake, genetic variation, environmental factors, genotype-environment interaction, mechanistic models, calibration, model validation, leaf area index, nutrient partitioning, vegetative growth, dry matter accumulation, inflorescences, photosynthesis, nutrient use efficiency, stomatal conductance, senescence
The objective of this study was to develop a mechanistic model for simulating the genotypic and environmental variation in rice growth and yield based on measured plant N accumulation. The model calibrations and evaluations were conducted for rice growth and yield data obtained from a cross-locational experiment on 9 genotypes at 7 climatically different locations in Asia. The rough dry grain yield measured in the experiment ranged from 71 to 1044gm⁻² over the genotypes and locations. An entire process model was developed by integrating sub-models for simulating the processes of leaf area index development, partitioning of nitrogen within plant organs, vegetative biomass growth, spikelet number determination, and yield. The entire process model considered down-regulation of photosynthesis caused by limited capacity for end-product utilization in growing sink organs by representing canopy photosynthetic rate as a function of sugar content per unit leaf nitrogen content. The model well explained the observed genotypic and environmental variation in the dynamics of above-ground biomass growth (for validation dataset, R ² =95), leaf area index development (R ² =0.82) and leaf N content (R ² =0.85), and spikelet number per unit area (R ² =0.67) and rough grain yield (R ² =0.66), simultaneously. The model calibrations for each sub-model and the entire process model against observed data identified 10 genotype-specific model parameters as important traits for determining genotypic differences in the growth attributes. Out of the 10 parameters, 5 were related to the processes of phenological development and spikelet sterility, considered to be major determinants of genotypic adaptability to climate. The other 5 parameters of stomatal conductance, radiation extinction coefficient, nitrogen use efficiency in spikelet differentiation, critical leaf N causing senescence, and potential single grain mass had significant influence on the yield potential of genotypes under given climate conditions.