Genetic assessment of yield and quality traits in aromatic rice (Oryza sativa L.)
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Date
2012-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The present investigation was conducted during Kharif, 2010 at Norman E. Borlaug Crop Research Centre, Pantnagar with the following objectives: (i) to work out the combining ability of parents and their all possible crosses for grain yield and quality characters, (ii) to elucidate the nature of gene action, (iii) to determine the extent of heterosis, heritability and genetic advance and (iv) to study the association between yield and its components as well as to ascertain direct and indirect effects of component characters on seed yield. The experimental material comprised of eight aromatic cultivars, 28 F1’s generated following a half diallel mating design and two checks, Pusa basmati-1 and Basmati-370. Observations were recorded on 23 (10 field and 13 quality) characters. Analysis of variance revealed that these genotypes differed significantly for all the characters except for panicle length indicating the presence of ample amount of variability among genotypes. High heritability estimates coupled with high genetic advance was observed for number of kernels per panicle, seed yield /plant,
percent harvest index, cooked kernel L/B ratio, cooked kernel length, elongation ratio, biological yield per plant and per cent head rice recovery. Considerable heterosis over the mid parent, better parent and both the checks was observed with respect to all the characters under study. The nature and magnitude of heterosis revealed that high heterosis for grain yield was mostly accompanied by heterosis for major yield contributing traits. It is evident that crosses exhibiting high extent of heterosis posses high sca estimate. This indicated that manifestation of heterosis depend upon sca estimates. Combining ability analysis revealed that the gca and sca variances were significant for most of the characters under study indicating importance of both additive and non-additive genetic variances. The magnitude of SCA variance (σ2S) was greater than GCA variance (σ2g) for most of the characters suggesting preponderance of non-additive gene actions and revealed suitability of material for hybrid breeding. The GCA effects of the parents indicated that the parent, Pant sugandh Dhan-17 to be the best general combiner with 11 characters in desired direction followed by Sugandhmati with 10 characters. The top three specific combiners for seed yield per plant were Pant Sugandh Dhan-15 x Pant sugandh Dhan-17, Sugandhmati x Pant sugandh Dhan-17 and Pusa Sugandh-4 x Pusa Sugandh-6. Seed yield per plant showed positive and highly significant correlation with harvest index, number of spikelets per panicle, biological yield per plant, flag leaf length, number of effective tillers per plant, days to 50% flowering, plant height and panicle length. Harvest index (%) was the most important direct contributor towards seed yield per plant followed by biological yield per plant, days to 50% flowering, 1000-grain weight, panicle length and number of spikelets per panicle. Therefore these characters can strategically be used as selection criteria in yield improvement programme of aromatic rice.
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