Parameterization of leaf growth in rice (Oryza sativa L.) utilizing a plant canopy analyzer

Monitoring leaf growth is a useful method for evaluating crop growth. In this study, frequent measurements of the rice canopy were conducted with a plant canopy analyzer, and parameters were estimated by applying several equations to evaluate leaf growth. The applicability of this evaluation method is discussed based on the statistical analysis of parameters. Experiments were conducted for 6 rice cultivars under 5 treatments in 2 years. Parameters describing the dynamics of leaf growth were obtained by applying 4 mathematical growth models in which the independent variable was the effective accumulated temperature. The parameters numerically represented the dynamics of leaf growth in each cultivar and treatment. In particular, maximum LAI and interception growth rates (MLGR and MIGR) which were obtained by applying logistic function to leaf area index (LAI) and diffuse non-light intercepted (DIFN), respectively, showed no interaction between the cultivar and environment. The lack of interaction may indicate that these parameters typically characterize cultivar and growth environments. The differences in the parameters could also be used to quantify the effect of basal fertilizer application on leaf growth enhancement and that of additional fertilizer on the extension of this enhancement. These results suggest that the applied method for parameterizing leaf growth based on frequent measurements with a canopy analyzer is suitable for evaluating the effects of genotype, management and the environment because it facilitates measurements in many plots.