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Language: en
Type: Thesis
Series/Report no.: D9829;
Agrotags: grain, hybrids, developmental stages, planting, yields, heterosis, rice, productivity, fertilizers, biological phenomena
Abstract: The present investigation entitled “Studies on Combining Ability and Blast Resistance in Hybrid Rice (Oryza sativa L.)” was undertaken to identify the effective restorers and maintainers among the elite lines. Based on the results, 12 parents were selected and mated in line × tester mating design to study the combining ability and magnitude of heterosis of experimental hybrids for grain yield per plant and yield contributing characters in Telangana. Out of 23 lines screened for restorer and maintainer reaction 12 lines exhibited very high spikelet fertility (>75%), 8 lines exhibited partial fertility (50 to 75%), 3 lines resulted low fertility (0.1 to 50%) and none of the lines recorded complete sterility (0%). Based on the results, 12 R lines were identified as male parents and crossed with three CMS lines (IR 72081A, IR 68902A, IR 58025A) in line × tester mating design resulting in 36 hybrids. The 15 parents, 36 hybrids and a hybrid check, PA-6129 were evaluated at Rice Research Centre, Rajendranagar of Telangana during Kharif 2014 for combining ability and heterosis. Further blast screening experiment was done during Rabi 2014-15, using the checks, IR-64 and TN1. The analysis of variance for grain yield and yield contributing characters revealed significant difference between the treatments for all the characters under study indicating that there was sufficient variability among the lines tested. Hence, combining ability analysis was carried out. The analysis of variance for combining ability revealed significant difference between the treatments for grain yield per plant and all the component traits, thus justifying their use in the present investigation. Similarly, hybrids also varied considerably between themselves, suggesting the wide variability among the crosses. The parents vs crosses were significant for all the characters studied except panicle length, number of unproductive tillers per plant and grain length-breadth ratio. Significance of parents vs crosses indicates that significant heterosis is observed for these traits. Further, crosses partitioned into lines, testers and lines × testers. The lines were found significant for all the characters; the testers were significant for majority of characters except panicle length, flag leaf width and spikelet fertility per cent; while the interaction between lines and testers were significant for all the traits studied which suggests sufficient variability. On the whole, based on the mean performance, GCA effects and SCA effects, IR 72081A was best among the testers while among the lines, MTU 1010, RNR 15038 and IR 64 performed better. Among the hybrids IR 58025A × MTU 1010, IR 68902A × RNR 15038 and IR 72081A × RNR 15038 performed superior to check PA 6129 in the present investigation. Heterosis for single plant yield is mainly because of simultaneous manifestation of heterosis for yield component traits. Out of 36 hybrids studied, the significant standard heterosis is observed in 3 hybrids viz., 58025A × MTU 1010 (18.25), IR 68902A × RNR 15038 (14.59) and IR 72081A × RNR 15038 (9.57) over the hybrid check, PA 6129. From the blast screening experiments by UBN (Uniform Blast Nursery) method, it was found that 22 hybrids and 5 parents are resistant to screening reaction; 14 hybrids and 7 parents are moderately susceptible; and 3 parents are highly susceptible to the blast disease. The parents which showed resistant reaction were IR 64, NLR 33358, KNM 118, RNR 15048 and RNR 15038 which can be used as parents for development of blast resistant varieties and hybrids. Among the top 10 hybrids with high yielding per se performance, 8 hybrids showed resistant reaction. The best hybrids identified with blast resistance are, IR 72081A × MTU 1010, IR 72081A × IR 64, IR 72081A × RNR 15038, IR 72081A × RNR(RK) 28, IR 72081A × RNR(RK) 53, IR 68902A × IR 64, IR 68902A × RNR 15038 and IR 58025A × MTU 1010. Character association and path analysis revealed that the traits viz., productivity/ day, days to 50 per cent flowering, grain length, number of productive tillers per plant, panicle weight, number of filled grains per panicle, 1000 grain weight, flag leaf width and flag leaf length have direct positive effect on grain yield per plant. Therefore, it is suggested that preference should be given to these characters in the selection programme to isolate superior lines with genetic potentiality for higher yield in rice genotypes. From this study, three hybrids viz., IR 58025A × MTU 1010, IR 68902A × RNR 15038 and IR 72081A × RNR 15038 were identified as best hybrids with high significant standard heterosis for grain yield and yield contributing characters, high SCA effects and blast resistance. These hybrids are recommended for further testing over locations and seasons, for stable performance.
Issue Date: 2015
Appears in Collections:Theses

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