Breeding for two line hybrids in rice (Oryza sativa L.)

Abstract

The present investigation entitled “Breeding for two line hybrids in rice (Oryza sativa L.)”was conducted in the Department of Plant Breeding and Genetics, College of Horticulture, Kerala Agricultural University during 2002-2005. Field trails were laid out at experimental fields of College of Horticulture Vellanikkara (COH) and Cardamom Research Station (CRS), Pampadumpara of Kerala Agricultural University. The experimental materials consist of TGMS lines collected from Tamil Nadu Agricultural University. HYVs from different Research Stations of Kerala viz. Moncompu, Pattambi and Mannuthy formed pollinator parents. The primary investigation was carried out at College of Horticulture, Vellanikakra to study the sterility/fertility behaviour of TGMS lines. It was found that February to May season can be considered as the ideal period for exhibiting 100 per cent sterility to utilize this period for the hybrid seed production. The study at COH, about the sterility behaviour of TGMS lines revealed that >32.20C during day time and >220C during night time are sufficient to make the lines completely male sterile. Experiments at Cardamom Research Station, Pampadumpara indicated that the region is suited for the maintenance and multiplication of TGMS lines. The study at CRS, Pampadumpara proved that 290C maximum temperature and 190C minimum temperature as the Critical Fertility Points of TGMS lines. Evaluation of 25 high yielding pollinator parents indicated that taller genotypes having more number of productive tillers plant-1increased straw yield and optimum growth duration are indicative of higher grain yield. TS29-1 was found to be a better line for higher hybrid seed production. Natural pollination with suitable pollinator parents was proved to be a viable method for the production of two line hybrid seeds. The allogamous traits of TGMS lines viz. total number of spikelets panicle-1, total number of tillers plant-1, SER, angle of glume opening and anther length will increase OCR. The 34 two line hybrids evolved through natural pollination with pollinator parents exhibited higher mean value for the characters such as panicle length, total number of spikelets panucle-1, number of filled grains panicle-1, grain yield and straw yield. Out of 25 pollinator parents, 21 could restore fertility in TGMS lines indicating that all these 21 parents can be used for evolving two line hybrids. Based on the gca effects of male parents Asha, Panchami, Krishnanjana, Ahalya, Aruna and Uma were good general combiners. Ten promising two line hybrids were TS29-1 x Aruna, TS29-1 x Makom, TS29-1 x Remya, TS29-1 x Panchami, TS29-1 x Uma, TS29-2 x Asha, TS29-2 x Krishnanjana, TS29-2 x Annapoorna, TS29-2 x Bharathy and TS29-2 x Ahalya. All the two line hybrids recorded significant positive heterosis for ear head characters, grain yield and straw yield (except TS 29-1 x Revathy).Twenty one F1 hybrids had more than 50 per cent heterosis over standard check Jyothi for grain yield. Superior ten crosses with respect to Jyothi had heterosis ranged from 80.58 per cent to 122.04 per cent for grain yield. Straw yield showed more than 30 per cent standard heterosis for these top ten crosses. All these hybrids recorded intermediate amylose content and acceptable cooking quality parameters including red kernels much preferred by Keralites. All the two line hybrids had black coloured stigma, an ideal character for early rouging of off types. Proline content of these hybrids was higher suggesting their improved stress tolerance.