MSc

The present study entitled “Evaluation of CMS based rice hybrids developed from rice varieties of Kerala identified as restorers” was carried out in the Department of Plant Breeding and Genetics, College of Agriculture, Vellayani during 2016-2018, with an objective to evaluate CMS based rice hybrids developed from rice varieties of Kerala as restorers, for heterosis for yield and grain quality. The study was conducted in two experiments i.e., 1) Hybrid seed production 2) Evaluation of hybrids. The first experiment, on hybrid seed production was undertaken in College of Agriculture, Vellayani during May to August, 2017 (Virippu, 2017).
Two CMS lines viz., CRMS31A and CRMS32A were crossed with nine restorers. Restorers were sown in three staggers, 10 days before the sowing date of CMS lines, at the sowing date of CMS lines and 10 days after the sowing date of CMS lines. Synchronized flowering dates of the CMS and restorer lines were recorded. CRMS31A was crossed with Remya, Jayathy, Swarnaprabha, Kanakom and Neeraja. CRMS32A was crossed with Annapoorna, Aiswarya, Mattatriveni and Kanakom. Six crosses i.e., CRMS31A x Jayathi (H1), CRMS31A x Kanakom (H2), CRMS31A x Remya (H3), CRMS32A x Annapoorna (H4), CRMS32A x Kanakom (H5), CRMS32A x Mattatriveni (H6) that had given more than 1500 viable seeds were carried forward for hybrid evaluation. Date of sowing of the restorers and maintainers for getting synchronization in flowering to undertake hybridization was standardized in this experiment.
In the second experiment, hybrids along with the better parent and checks were evaluated in a Randomized Block Design (RBD) with three replications during October 2017 to February 2018 (Mundakan) in IFSRS (Integrated Farming System Research Station), Karamana.
Observations on 12 yield contributing traits and 8 grain quality traits were recorded in the hybrids. Genetic parameters calculated from these observations showed that the GCV and PCV values for the characters studied did not vary greatly indicating low influence of the environment in these characters.
The mean performance of hybrids showed that the yield plot -1 was the highest for H5 (CRMS32A x Kanakom) followed by H3 (CRMS31A x Remya), H1 (CRMS31A x Jayathi), H2 (CRMS31A x Kanakom) and H4 (CRMS32A x Annapoorna). The hybrid H5 (CRMS32A x Kanakom) showed the highest mean values for plant height, number of filled grains panicle-1, length breadth ratio of grain and grain yield (g) plant-1. Pollen fertility of the hybrid H3 (CRMS31A x Remya) was superior to the standard check. This shows that the variety Remya is a complete restorer for male sterile cytoplasm CRMS31A. Hybrid H5 also showed pollen fertility on par with the check showing that the variety Kanakom is restorer for CRMS32A. The other hybrids H4 (CRMS32A x Annapoorna) and H6 (CRMS32A x Mattatriveni) had pollen fertility per cent around 50. So the male parents Annapoorna and Mattatriveni for CRMS32A can be considered as only partial restorers. The low level of pollen fertility was the reason for low yield of hybrids H4 (CRMS32A x Annapoorna) and H6 (CRMS32A x Mattatriveni) despite high number of productive tillers.
Five out of six hybrids were red kernelled. It was found that the hybrids inherited the kernel colour from the male parents. The kernel length by breadth ratio of all the hybrids was significantly higher than that of Uma. The hybrids had a medium to slender grain shape (kernel length by breadth ratio 2.1 to 3 and above). This may be the reason behind the phenomenon of curling noted in cooked rice in all the rice hybrids studied.
Standard heterosis for yield plot-1of the hybrids calculated over the standard check variety Uma was the highest for H5 (CRMS32A x Kanakom) followed by H3 (CRMS31A x Remya) and H1 (CRMS31A x Jayathi). Heterobeltiosis for yield calculated over the better parent was maximum for H1 (CRMS31A x Jayathi) followed by H5 (CRMS32A x Kanakom). Amylose content of most of the hybrids fell into intermediate category along with that of the check variety Uma, showing the hard and non sticky nature of the cooked rice of the hybrids. Cooking time for hybrids was less compared to that of Uma (29 minutes).
This evaluation of hybrids could identify two promising hybrids for Kerala H5 (CRMS32A x Kanakom) and H3 (CRMS31A x Remya) which could give a yield advantage of 17.91% and 16.37% over the popular rice variety Uma. These two hybrids had long slender grain shape with red kernel colour. The amylose content of these two hybrids was also intermediate and low. These hybrids had a lower cooking time and good head rice recovery. Hence the hybrids can be recommended for Kerala after trials over locations and seasons. A better seed production technique has to be standardized before commercial release.