Abstract
In the marker-assisted selection for breeding high-yielding rice, the target traits need to be identified and characterized. Habataki, identified as an indica type and high-yielding cultivar, has been employed in the research for analyzing quantitative trait loci (QTL). In this study, we investigated ecophysiological characteristics contributing to the high grain yield of Habataki compared with Sasanishiki (japonica type). Grain yield was 60—120g m-2 higher in Habataki than in Sasanishiki due to a significantly higher harvest index. Habataki showed a higher crop growth rate (CGR) during the period from the booting to the early ripening stages, which might contribute in part to the higher harvest index in Habataki. Habataki had a higher photosynthetic rate in the morning and maintained a higher rate in midday and afternoon, which might be attributed to the higher CGR during early ripening. Habataki had longer roots with larger surface area and, therefore, lower resistance to water transport from root to leaf than Sasanishiki, which might be attributed to the maintenance of higher photosynthetic rate until afternoon. It would be useful for improving grain yield to identify the QTL related to the high photosynthetic rate and water transport capacity of Habataki, and introduce it into the japonica-type rice.
