The relationships between harvest index, grain yield and biomass in rice

O. Mohamad, O. Suhaimi and M. Z. Abdullah

Abstract

Harvest index, grain yield and biomass were significantly higher in the main season than in the off-season for most of the 20 released varieties studied. Significant non-linear relationships were observed for harvest index and grain yield, and for grain yield and biomass. The study indicated a general tendency of improvement in harvest index and grain yield among the released varieties. Kadaria (42.4%) and MR 84 (40.5%) had the highest harvest index in the offseason 1988, while harvest indices of Setanjung (51.3%) and MR 84 (49.1%) were highest in the main season 1988/89. Malinja and Mahsuri had the highest grain yields in the off-season while that of MR 84 and Setanjung were highest in the main season. Although the relationship between grain yield and biomass was strongly positive, it was observed that the recent released varieties achieved higher yield without concomitant increase in biomass. Increase in grain yield, accompanied by increased harvest index, was probably attributed to increase in partitioning efficiency.

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