Heterosis and heterobeltiosis for high density grain index (HDI) and other rice panicle characters
1989
Mallik, S. | Aguilar, A.M. | Vergara, B.S. (International Rice Research Inst., Los Banos, Laguna (Philippines). Plant Physiology Dept.)
Estimates of overall degree and direction of heterosis (Fmac1-Pmac) were significantly positive for number of tillers (1.74), PB (1.27), SB (3.28), spikelets on PB (8.65), spikelets on SB (8.41), and sterility on SB (5.37), indicating dominance of higher values. Heterosis was negative only for number of spikelets on PB (-3.01). Low or nonsignificant heterosis for other characters may be due to little genetic interactions or differences among parents. The individual F1 family differed from overall estimates for different characters showing positive, negative or no heterosis. The F1 means deviated conspicuously from parental and midparental values, indicating involvement of nonadditive gene action in the expression of most characters. Substantial heterosis in the desirable direction was observed in PB number, spikelets on PB, and HDI on PB and SB. Three crosses among HD-grain parents (P1/P2, P5/P2, P2/P6) and one cross between HD- and LD-grain parents (P2/P8) exhibited positive heterosis and heterobeltiosis for number of PB and spikelets on PB. Only two crosses, P5/P2 and P2/P8, manifested positive heterosis and heterobeltiosis for HDI on PB. The cross P2/P8 showed positive heterosis for all characters except sterility on PB and SB, where negative heterosis is desirable. Two crosses, P3/P4 and P3/P7, showed negative haterosis for almost all characters. Number of HD grains was higher on PB of parents and hybrids. Substantial heterosis for this character may lead to higher yield, since HD grains have higher test weight and higher head rice recovery. The cross P2/P8 had positive heterosis for all desirable traits and exceeded the highest parent of HDI on both PB and SB.
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