Genetics of fertility restoration 2 in six varieties and breeding lines of rice was studied in 'Wild Abortive' cytoplasmic genetic male sterility system using cytoplasmic male sterile lines V 20 A and IR 54752 A. Fertility evaluation of the plants in F2 and testcross populations of the crosses of V 20 A with PR 103, PR 106 and PAU 502-94-1, and IR 54752 A with PAU 1124-36-1 and PAU 1126-1-1 revealed that fertility restoration in PR 103, PR 106, PAU 502-94-1, PAU 1124-36-1 and PAU 1126-1-1 was controlled by two independently segregating dominant genes. The two genes appeared to have additive effects; one of them being stronger than the other in imparting fertility restoration. Data on spikelet fertility of the plants in F2 and testcross populations of V 20 A/UPR 82-1-1 cross showed that fertility restoration in UPR 82-1-1 was controlled by two independently segregating dominant genes which exhibited recessive epistatic interaction.

Heterosis for yield and four yield components, viz. panicle number per plant, panicle length, spikelet per panicle and lOOO-grain weight, was studied in fifteen crosses involving six varieties of rice, Uryza sutiva L. Positive and significant heterosis for yield was observed in 11 and 8 crosses, over the midparent and the better parent, respectively. Hamsa x Hybrid 27 gave the highest heterosis both over the mid-parent (156.23 %) and the better parent (136.38%) followed by Jaya x Norin 18 with respective values of 155.18 and 56.29%.As compared with the average yield of 36.54 g per plant of the high yielding commercial variety, viz.