Abstract

                                Hybridization programme involving seven resistant sources of leaf folder and seven popular strains was launched at the Paddy Breeding Station, Coimbatore and crossed seeds were obtained. Twenty three hybrid combinations and their respective parents were raised in randomised block design replicated twice. Six economic traits were studied in randomly selected twenty hybrids and parents. Heterosis, heterobeltiosis and standard heterosis were computed and significance was worked out for heterosis. The study revealed that three crosses viz, IR. 36 x W 1263. IR 20 x IR 4707-106- 3-2 and IR 20 x Muthumanickam manifested heterosis for the six characters studied. The manifestation of heterosis in all the 23 cross combinations might be due to additive gene effects and the negative heterosis observed might be due to the disharmony of the gene combinations prosent in different parents.

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