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ArticleItem Open Access HETEROSIS BREEDING IN RICE (ORYZA SATIVA L.) FOR QUANTITATIVE TRAITS(Plant Archives, 2019) Singh, N.K.The magnitude as well as direction of heterosis over better parent and standard variety differed from character to character depending upon cross combinations. The manifestation of heterosis for grain yield plant-1 is evident by significant superiority of hybrids over better parent ranging from -54.69 to 139.43 per cent and over standard variety ranging from 60.35 to 22.64 per cent. In general, the crosses which displayed superiority over better parent and standard variety for grain yield also exhibited significant heterosis for some yield contributing traits. Besides, exhibiting exploitable level of hybrid vigour for yield, most of these hybrids except few also showed heterosis for earliness closer to the standard variety. Therefore, these hybrids are useful as they produced more yield day-1 in comparison to standard variety and may fit well in multiple cropping systems. Most of the hybrids possessed higher number of seed set than pollen parent and standard variety but percentage was low due to hybrid sterility as one of the parent used as CMS line. So far heterosis over standard variety was concerned, 50% hybrids showed significant superiority for harvest index, ear bearing tillers plant-1, 1000 grain weight, biological yield whereas only 40% hybrids were observed better for days to 50% flowering and days to maturityArticleItem Open Access ESTIMATES OF GENETIC PARAMETERS, COMPONENTS OF VARIANCE AND THEIR MAGNITUDE IN RICE (ORYZA SATIVA L.)(Plant Archives, 2019) Singh, N.K.The relative contribution of males x females was higher than that of males and females for the expression of all the characters except total number of spikelets and number of fertile spikelets. Males exhibited maximum contribution for ear bearing tillers plant-1. In general, phenotypic coefficient of variation was higher than genotypic coefficient of variation for all the characters. Phenotypic and genotypic variations were lower for days to 50% flowering, plant height, days to maturity, ear bearing tillers plant-1 and total number of spikelets plant-1, indicating little opportunity of selection for these characters. Other characters showed more variation among phenotypic and genotypic values. Heritability in narrow sense (h2n) ranged from 5.18 for days to maturity to 20.27 for ear bearing tillers plant-1. Highest h2n estimate was recorded for ear bearing tillers plant-1. Moderate h2n estimates were observed for remaining traits except days to 50% flowering, biological yield, harvest index, plant height and days to maturity which, were of lesser order. Estimates of h2b were recorded high for all the characters except days to maturity.ArticleItem Open Access Study of line x tester analysis, combining ability and per se performance in rice (Oryza sativa L.)(Journal of Pharmacognosy and Phytochemistry, 2018) Singh, N.K.The analysis of variance for combining ability revealed significant differences due to lines and testers for all the characters indicating wide genetic diversity among lines and testers. The lines x testers’ interaction components also emerged significant for all the twelve traits which indicated that combining ability contributed more in the expression of these traits. Among the CMS lines, IR 58025A having ‘WA’ type of cytoplasm was found to be good general combiner for grain yield and its major components. The line, NDMS 4A was poor general combiner for grain yield and most of the components but showed better ability to combine for plant height and panicle length. Among restorer lines, CR 792-B4-2-1R was found good general combiner for grain yield and biological yield. Other good combiner was TTB 517-17-SBIR-70149-35R noticed for total number of spikelets panicle-1, number of fertile spikelets panicle-1 and number of sterile spikelets panicle-1. The higher magnitude of sca than gca variances and greater value of average degree of dominance and lower predictability ratio were observed for all the twelve characters except days to maturity, suggesting significant role of non-additive gene action for these traits which results from dominance /epistasis and various other interaction effects that are non-fixable.ArticleItem Open Access GENETIC VARIABILITY IN RAIN-FED LOWLAND RICE BREEDING POPULATION UNDER NORMAL AND DELAYED TRANSPLANTING CONDITIONS(International Journal of Agriculture Sciences, 2017) Singh, N.K.The importance of additive gene effects for most of the nine traits in the three crosses under two transplanting conditions suggested substantial scope of improvement in yield status can still be achieved by using breeding procedures. GY/P, BY/P and PH possessed high heritability and genetic advance in both conditions and emerged as ideal traits for selection. G/P, T/P and DFF in E1 and HI in E2 appeared also as ideal traits for selection owing to their high estimates for both parameters in respective conditions. At both levels, positive correlation of GY/P was recorded with HI in both transplanting conditions. BY/P, PL in both transplanting conditions and T/P and G/P in E1 appeared as strong positive associates of GY/P at both levels. Path analysis identified BY/P and HI as most important direct components and PL and G/P as most important indirect components of GY/P in both conditions. These characters merit due to consideration in formulating effective selection strategy in rainfed lowland rice for developing high yielding varieties for normal and delayed transplanting.