Development of a Method for Evaluating Vertical Leaf Area Distribution in Rice.

Vertical leaf area distribution is the principle factors that determine light radiance distribution and leaf physiological characteristic in crop canopies. However, a laborious work of destructive samplings is commonly necessary to evaluate, limiting the information of vertical leaf area distribution. In this study, we used a plant canopy analyzer, LI-COR LAI-2200, which is a non-destructive and non-laborious equipment to measure leaf area index (LAI), and evaluated vertical leaf area distribution and its dynamical change in rice.

Field experiments were conducted at the experimental fields in Kyoto University with two fertilizer treatments in 2013 and with three plant density treatments in 2014. Three cultivars, Nippobare, Takanari and Shennong265 (common japonica, high-yielding indica and erect panicle type of japonica, respectively) were planted. LAI of every 10 cm-height (stratified measurement) in each plot was measured by LI-COR LAI-2200 once or twice a week. LAI vertical distribution was also measured destructively by the stratified clipping method at panicle initiation and heading. The measurement was analyzed by the moment equations.

Stratified measured LAI by LAI-2200 was closely correlated with that by stratified clipping method at every treatments and cultivars, suggesting that the vertical leaf area distribution can be evaluated by LAI-2200. Statistical moments, center, variance, skewness and kurtosis, based on the vertical leaf area distribution showed that Shennong265 has a significantly different canopy from the other cultivars. The moments also reveal that vertical leaf area distribution varied with time and fertilizer treatments.

These results suggest that the statistical moments evaluated in this method quantitatively provide the information of vertical leaf area distribution. The information might help us to understand the effect of canopy structure to dry matter production.