Development of Sugarcane Leaf Erectness Index using Leaf Morphological Features

抄録

Improvement of the sugarcane canopy structure using varietal diversity in leaf erectness should effectively increase the number of millable canes, which is highly correlated with cane yield. Traditionally, leaf erectness has been evaluated with visual observations; however, quantitative analyses using leaf morphological features would be a more practical means of selecting optimal leaf erectness. The objective of this study was to develop a new evaluation method using the leaf features to characterize the leaf erectness. Thirty-seven sugarcane genotypes were evaluated by means of leaf silhouette sketches. The correlation between the conventional leaf-erectness scores and the leaf features suggested that the aboveground height of leaf tips best characterizes varietal leaf erectness. Therefore, we developed a leaf erectness index (LEI) as the ratio of leaf tip height to aboveground height of its dewlap. The values of the LEI were useful for characterizing leaf erectness because they significantly correlated with the leaf-erectness score with indices ranging continuously from 0.36 to 2.55. When quantifying LEI at different growth stages and under differing environmental conditions, it is better to compare the measured LEI for a given variety to the LEI of a standard variety.