Development and evaluation of restorers and their relationship with heterosis in rice (Oryza sativa L.)

Abstract

One hundred and sixteen restorers whose hybrid combinations had been ,evaluated in the national testing were critically evaluated in the field for two years. Those were grouped as high, medium and low based on Duncan's Multiple Range Test (DMRT) and mean and standard deviation of joint scores. More than 75% of the entries were found in the same groups in both the years indicating a very high reproducibility and repeatability of the method of grouping. Only 50 restorers out of 116 were found to give heterotic hybrids with an yield advantage of 1.0 t ha-1 or more over the best inbred check variety. Majority of the restorers (>86%) showing heterosis were from the medium group emphasizing the need to select restorers from this group in order to develop heterotic hybrids. In another experiment, 28 Fs lines derived from a eMS based hybrid IR 62829A1 WGL 3962 were crossed with IR 62829A to assess the potential of newly developed iso-cytoplasmic restorers. The F, crosses were evaluated along with the original hybrid, IR 62829A1 WGL 3962. Results indicated that only 32% of the restorers were able to restore the complete fertility in hybrids implying that the restoration is governed by more than one gene. Nearly 14% of the crosses _involving new restorers showed significant heterosis over the original hybrid from which they were derived indicating that there were heritable genetic factors responsible for heterosis. Selection of restorers based on the joint scores of a number of dependent traits appears to be a sound criteria to develop heterotic rice hybrids.