Comparison of plant type between new and old rice cultivars using computer image analysis.

Abstract

Computer image analysis of a side-view photograph of a plant was applied to compare the plant type between eight new and seven old Japanese rice cultivars grown in a paddy field. Photographs of these cultivars were taken at heading time (stage 1) and three weeks after the heading (stage 2). The distribution of shoot density (percentage of shoot (leaf+stem+panicle) presence in a unit area) was shown by contour lines as seen in a map. The morphological shape was characteristic to each cultivar and stage, and the difference of the shape of cultivars became more prominent after the heading. The characteristics of cultivars were compared by numerical parameters calculated from the density map. In the old cultivars the shape expanded at the upper part or at the lower-middle part, while new ones had less expanded part, though Koshihikari was an exceptional case. The old cultivars showed prominently dispersing nature at stage 2, while the new ones did not disperse. As for the leaf angle, the new cultivars had more vertical leaves at the upper part than old ones at stage 2. The morphological characteristics of each cultivar and their difference at the heading time and after heading were well displayed by the present Plant-Profile-Processing method (PPP method).