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2011 - 20132
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Subject: Plant Breeding and Genetics ×

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    ThesisItemOpen Access
    Genetic Analysis in Relation to Yield and Quality Characters in Indica Rice (Oryza sativa L.)
    (2011) Mehfuza Habib; Parray, G.A.
    The present investigation entitled “Genetic analysis in relation to yield and quality characters in indica rice (Oryza sativa L.)” was carried out to generate information on degree of interrelationship and combining ability (general and specific), nature and magnitude of gene effects and heterosis for yield and yield attributing traits. Parents were assessed for some quality traits and diversity of parents at molecular level was assessed using SSR markers. The experimental materials comprised a diallel set involving eight diverse parents excluding reciprocals. The experimental materials were evaluated in a randomized complete block design with two replications over two locations, namely Regional Rice and Research Station, Khudwani (E1) and Experimental Farm, Division of Plant Breeding and Genetics, Shalimar (E2) of SKUAST (K) during Kharief, 2008. The data were recorded on days to 50% flowering, days to maturity, number of tillers plant-1, plant height (cm), panicle number plant-1, panicle length (cm), grain weight panicle-1 (g), total spikelets panicle-1, grain yield plot-1 (kg), number of seeds panicle-1 and 1000-grain weight(g). The quality parameters for which parents were studied included L/B ratio of grain, milling(%), head-rice recovery(%), gelatinization temperature, volume expansion ratio and amylose content(%). Significant variability and G x E interaction was observed for all the traits indicating that the behavior of parents and crosses was not similar in the random set of environments. Grain yield plot-1 exhibited a significant positive correlation with number of tillers plant-1, panicle length, number of seeds panicle-1, grain weight panicle-1 and 1000-seed weight. The mean values were used for statistical analyses and estimation of genetic parameters following diallel analysis. Analysis of variance revealed significant differences among the parents and their crosses for all the traits indicating that the material selected were diverse for all the morpho-agronomic traits. The variance due to GCA and SCA was significant for all the traits which showed that both were important in the inheritance of the traits. Significant interaction between combining ability effects and environments were observed for all the traits. Estimates of combining ability revealed that SKAU-382, Jhelum, Chenab, Ch-1039 and SKAU-5 were desirable combiners for days to 50% flowering, whereas SKAU-389, Jhelum and SR-1 were desirable combiners for grain yield plot-1. The most promising crosses that revealed highly positive and significant SCA effects for yield were Jhelum x Ch-1039, SKAU-389 x Ch-1039 and SKAU-382 x SKAU-5. Component analysis revealed higher magnitude for dominance variation for all the traits. Graphical analysis indicated complete dominance in case of total spikelets plant-1 and number of seeds panicle-1, whereas over-dominance was observed for rest of the traits. Maximum heterosis for grain yield plot-1 was registered in Jhelum x Ch-1039, Chenab x Ch-1039 and SKAU-382 x SKAU-5 (mid and better parent estimates). Based on the study carried out, it is concluded that diallel selective mating scheme could be implemented to exploit non-additive gene action which was preponderant in the materials. The SSR primers used revealed distinct polymorphism among the cultivars studied indicating the robust nature of microsatellite markers in revealing polymorphism.
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    ThesisItemOpen Access
    Heterosis and combining ability analysis for yield and component traits in rice (Oryza sativa L.)
    (SKUAST, 2013) Dar, Sajad Hussain; Rather, A.G.
    Realizing the potential of hybrid rice to increase productivity, the present study entitled “Heterosis and Combining Ability Analysis for Yield and Component Traits in Rice (Oryza sativa L.)” was carried to generate information regarding combining ability and its interaction with environment, nature and magnitude of gene action, heterosis for yield and yield attributing traits and also to generate the information regarding fertility restoring ability among the various lines. The experimental breeding material comprised of a diallel cross, excluding reciprocals (Experiment-I), and a line x tester mating design (Experiment-II). 27 F1 hybrids were generated through Line x Tester mating design by pollinating three CMS lines SKUA-7A, SKUA-11A and IR-68888A with nine testers namely Jhelum, Pusa Sugand-5 (PS-5), China-988, Shalimar rice-1, SKAU-382, SKAU-389, K-08-59, K-08-60, K-08-61 in Kharif 2011. Another set of 36 single crosses were generated in the same season by intermating the nine parents used as testers in experiment-I in all possible combinations excluding reciprocals. All the crosses and parents of each experiment along with two standard checks Jhelum and SR-1 were evaluated for various agronomic traits over two diverse locations viz. Mountain Research Centre for Field Crops, Khudwani (E1), and at the Experimental Farm of Krishi Vighyan Kandra (KVK) Pombay (E2) of Sher-e-Kashmir University of Agricultural Sciences & Technology of Kashmir during Kharif, 2012. The experimental design used was randomized complete block design with three replications. The observations were recorded on 18 morpho-agronomic traits viz. days to 50 per cent flowering, days to maturity, pollen fertility per cent, spikelet fertility per cent, number of spikelets panicle-1, number of filled grains panicle-1, panicle length, number of primary branches panicle-1, number of secondary branches panicle-1, number of tillers plant-1, number of productive tillers plant-1, plant height, biological yield plant-1, grain yield plant-1, harvest index, grain length, grain breadth and grain L/B ratio. Analysis of variance revealed significant differences among the genotypes for most of the characters studied. G x E interaction was observed to be significant for all the traits in the entire material indicating differential behavior of parents and crosses across environments. The variance due GCA and SCA was found significant for all the traits in both the experiments thus revealed that both additive and non-additive gene effects were important in the inheritance for these traits. Significant interaction between combining ability effects and environment was observed for most of the traits. The estimate of dominance deviations (sˆ 2D ) was higher than their corresponding additive genetic variance (sˆ 2 A ) for most of the traits in Experiment-I. However, both additive and non-additive genetic components were found equally important in experiment-II. None of the parents showed significant GCA effects in the desired direction simultaneously for all the traits studied. However, based on significant positive GCA effects for grain yield and components traits in individual and combined analysis SKAU-389, Jhelum, SKAU-382, and SR-1, in Experiment-I and K-08-60, K-08-61 and Pusa sugandh-5 in Experiment-II were found most promising. For grain yield plant-1, fifteen hybrid combinations in Experiment-I and seven combinations in Experiment-II had positive significant SCA effects at individual and pooled over environments. All these cross combinations were observed to have significant SCA effects for most of yield component traits. For grain yield plant-1 five promising crosses namely Jhelum x K-08-60, SKAU-389 x K-08-60, SR-1 x K-08-60, K-08-59 x PS-5, Ch- 988 x SR-1 in experiment-I and K-08-61 x SKAU-7A, PS-5 x SKAU-7A, K-08-61 x SKAU- 11A, K-08-60 x SKAU-7A and K-08-60 x SKAU-11A in experiment-II involved predominantly good x poor, poor x average, good x good and good x average combiners. Correspondence between SCA effects and per se performance was recorded for most of the traits in both experiments. Average degree of dominance was in over dominance range for most of the characters. The gene distribution was observed to be asymmetrical for all traits with positive and negative effects in parents for most of the characters. The value of KD/KR indicated presence of excess of dominant genes in parents for most of the traits, also the estimate of heritability (narrow sense) was recorded low in case of diallel experiment. Significant and desirable heterotic effects were observed for most of the characters studied. Maximum standard heterosis for grain yield plant-1 was registered by SKAU-389 x K-08-60 fallowed by Jhelum x K-08-60, SKAU-389 x PS- 5, Jhelum x SKAU-389 and China-988 x SR-1 in Experiment-I. Whereas in Experiment-II highest standard heterosis was recorded by PS-5 x SKAU-7A followed by K-08-60 x SKAU-11A and K-08-61 x IR-68888A. Three genotypes K-08-61, K-08-60 and PS-5 were found as effective restorers whereas Jhelum behaved as a maintainer for all the three CMS lines used in the study. High magnitude of standard heterosis in the favorable direction for grain yield and yield contributing traits coupled with availability of potential restorers and maintainers reveals the feasibility of hybrid rice breeding in this temperate region of the globe.