Heterosis in F1 Rice Hybrids

For practical exploitation of hybrid vigor in rice, emasculation is a major constraint, however, the use of male sterile lines increases the chance of identifying more heterotic hybrids. In addition, parents should perform well in hybrid combinations. Heterosis, heterobeltiosis and standard heterosis for 13 characters were studied from 5 crosses between rice (Oryza sativa L.) cultivars (improved and landraces) and three wild aborted male sterile lines. These crosses showed marked variations in the expression of heterosis, heterobeltiosis and standard heterosis for all characters. Grain yield manifested highly significant heterosis, heterobeltiosis and standard heterosis in five crosses. Heterobeltiosis ranging from –55 to 139% and standard heterosis from –11 to 369% were found for grain yield. The highest heterotic effect among the yield components was for panicle number plant-1 followed by spikelet number and panicle length. The highest level of heterosis (62.6%), heterobeltiosis (39.57%) and standard heterosis (19.37%) for plant height was expressed by the hybrid IR58025A/Kanchan. The F1 hybrids appeared useful for their high grain yield per cropping season as well as for other characters. The results indicated the possibility of obtaining more heterotic hybrids only in specific cross combinations. The performance of F1 was positively correlated with the mid parent and male parents for most of the characters. Therefore, selection of parental lines is the important factors for commercial utilization of heterosis. J. Inst. Agric. Anim. Sci. 2003 24:29-36