HETEROSIS IN IRRIGATED RICE

Abstract

The objective of this study was to evaluate heterosis, heterobeltiosis and standard heterosis for eight characteristics of irrigated rice (Oryza sativa L.) hybrids derivated from crosses among two A lines and 17 restorers lines. Field trials were conducted in Goinira, Goiás, Brazil. The experimental design was a completely randomized block with three replications. Results indicate a wide genetic divergence for grain yield on the restorers lines. All hybrids showed positive heterosis for grain yield and those presenting the highest values also demonstrated positive heterosis for different yield components. These data indicate that grain yield heterosis is a result of the interaction among heterosis observed for yield components. For tillers and panicles per square meter, the positive and negative values observed were similar in number and magnitude, for the three types of heterosis studied. Panicle length and 100 grain weight were the traits that contributed the most to yield heterosis. All hybrids presented shorter growth duration than the parents. Since the parents had short stature, plant height was not significantly changed in the hybrid offspring. Hybridization increased spikelet sterility, even among cultivars within the same Indica group.

KEY-WORDS: Oryza sativa; hybrid rice; grain yield; yield components.