Studies on the Varietal Difference of Harvest Index in Rice. Relationship between harvest index and morphological characteristics and leaf color.

Abstract

To find useful indexes for the selection of new rice varieties having a high harvest index, the correlation of harvest index (HI) with morphological characteristics and leaf color was examined using 60 Japanese varieties (J group) and 20 high-yielding varieties bred in Asian countries (H group). In the J group, HI showed a positive correlation with leaf color (SPAD value, SV) and a negative correlation with plant length (PL) at the heading time. In the H group, HI showed a positive correlation with SV, but the correlation coefficient between HI and PL was not significant. The correlation berween HI and culm length (CL) was similar to that between HI and PL. HI showed a negative correlation with ear length (EL) in the J group, but significantly positive correlation in the H group. There was a significantly positive correlation between EL/CL and HI in the H group. A multiple regression analysis was conducted to clarify the relationship berween morphological characteristics and HI. A significant multiple correlation coefficient was obtained between HI and SV (X1), PL (X2) or EL/CL (X3). The ratio of standard partial regression coefficient of X1, X2 and X3 to HI was 54:15:31. Consequently, it is considered that these morphological characteristics are useful indexes to select varieties with a high harvest index.