DIALLEL ANALYSIS OF HEAD RICE PERCENTAGE, TOTAL MILLED RICE PERCENTAGE, AND ROUGH RICE YIELD

The value of rough rice (Oryza sativa L.) is often determined by the percentage of head rice and total milled rice produced after milling. The objective of this study was to obtain information on general combining ability (GCA), specific combining ability (SCA), and high parent heterosis for head rice percentage, total milled rice percentage, and rough rice yield. An eight-parent diallel (F, crosses plus parents) was evaluated in 1991 at two Arkansas locations: Stuttgart and Marianna. Genetic variation among the hybrids for total milled rice percentage was nonsignificant. The GCA effects were more important than SCA effects for head rice percentage, indicating the importance of additive genetic effects in the inheritance of head rice percentage. It is postulated that head rice percentage SCA effects were due predominantly to additive x additive epistatic effects rather than dominance effects. Additive and additive x additive epistatic types of gene action are most easily exploited by producing homozygous genotypes. Single cross performance for head rice percentage could largely be predicted by GCA effects or mid-parent means. Average heterosis, as indicated by the Parent vs. Hybrid mean squares, was nonsignificant for head rice percentage, but significant for rough rice yield. High-parent heterosis for rough rice yield, head rice percentage, and head rice per plot averaged 21, -5, and 22%, respectively. High parent heterosis, obtained from the hybrids of this eight-parent diallel, for head rice per plot was due primarily to rough rice yield heterosis rather than head rice percentage heterosis. Based on the yield of head rice per plot, hybrid rice production would be feasible.