Dhaduk L. K.SODAVADIYA PARESH RAMESHBHAI2016-09-212016-09-212010-03http://krishikosh.egranth.ac.in/handle/1/77929In the present investigation entitled “Genetic architecture of seed yield and yield attributing traits in castor (Ricinus communis L.) under diverse environments” was undertaken with a view to generate genetic information on heterosis, combining ability, gene action, genotype x environment interaction and stability parameters for seed yield and yield attributing traits. The experimental material consisted of ten diverse genotypes of castor (SKP-42, Geeta, JI-244, JI-342, JI-353, JI-357, JI-371, DCS-89, PCS-124 and JI-338), their F1‟s derived by crossing these parents in a diallel fashion excluding reciprocals and GCH-6 as standard check. The experiment was laid out in kharif 2008 under three environments, created by three different date of sowing in randomize block design with three replications in each environment. Observations were recorded on days to flowering of main raceme, days to maturity of main raceme, plant height up to main raceme (cm), number of nodes up to main raceme, total length of main raceme (cm), effective length of main raceme (cm), effective branches per plant, number of capsules on main raceme, shelling out turn (%), 100-seeds weight (g), oil content (%) and seed yield per plant (g). The data were analyzed for heterosis and combining ability (Method II, Model I of Griffing, 1956). The genetic components of variation were analyzed following the method of Hayman (1954a) while, stability analysis was carried out as per model suggested by Eberhart and Russel (1966). Analysis of variance in individual as well as pooled over environments revealed significant differences among genotypes and existance of overall heterosis for seed yield per plant and yield attributes. The magnitude of heterosis over better parent was considerable for seed yield per plant; moderate to high for total and effective length of main raceme, number of capsules on main raceme, effective branches per plant; low to moderate for plant height, number of nodes per plant, 100-seed weight, shelling outturn and oil content. The magnitude of heterosis over standard check GCH-6 was low for seed yield per plant, 100-seed weight, oil content, shelling outturn, days to 50 per cent flowering and days to maturity, while it was moderate to high for plant height, number of nodes per plant, number of capsules on main raceme, effective branches per plant and total and effective length of main raceme. Among 45 hybrids, DCS-89 x PCS-124, JI-353 x PCS-124 and Geeta x PCS-124 recorded the significant and positive (desirable) heterosis over GCH-6. The cross SKP-42 x JI-371 followed by DCS-89 x PCS-124 and SKP-42 x JI-338 recorded the highest heterobeltiosis for seed yield per plant. The high heterosis in these hybrids was mainly due to high heterosis in one or more of their component traits. The combining ability analysis revealed significant general and specific combining ability variances for all the characters across the environments and these variances were largely influenced by environments. The specific combining ability variance were found more important compared to general combining ability for seed yield and all other characters except days to 50 per cent flowering, plant height up to main raceme, number of nodes up to main raceme and 100-seed weight. Parents JI-353, DCS-89 and PCS-124 were good general combiners for seed yield per plant. Among ten parents, PCS-124 and DCS-89 recorded the good general combining ability for all the yield attributing traits studied. The hybrids DCS-89 x PCS-124, JI-353 x PCS-124 and Geeta x PCS-124 recorded the highest sca effects for seed yield per plant along with high and desirable sca effects for most of the traits directly related to seed yield. As per Hayman diallel analysis the value of H1/D indicated over dominance for all the traits evaluated except for days to flowering of main raceme, plant height up to main raceme and number of nodes up to main raceme and 100-seed weight. The distribution of genes with positive and negative effects in the parents were nearly symmetrical for the traits like days to flowering of main raceme, plant height up to main raceme, total length of main raceme, effective length of main raceme, effective branches per plant, number of capsules on main raceme, shelling outturn, 100-seed weight, oil content and seed yield per plant indicating considerable degree of gene symmetry over all the loci. The estimates of KD/KR ratio was more than unity for all the characters except for days to flowering of main raceme, shelling outturn, 100-seed weight and seed yield per plant indicating high proportion of dominant genes in the parents for these traits. The estimates of ratio h2/H2 suggested the involvement of one group of genes showing dominance in all the traits except for total and effective length of main raceme, effective branches per plant, number of capsules on main raceme and seed yield per plant. Griffing and Hayman analysis revealed importance of additive as well as non-additive gene effects with high relative magnitude of non-additive gene effects for seed yield per plant as well as components directly related to seed yield. This situation suggested heterosis breeding for evolving highly productive hybrids. For overall improvement, biparental mating with reciprocal recurrent selection could offer the best promise. Alternatively, intermating and selfing or intermating between F2‟s showing transgressive segregation would also be helpful in isolating superior genotypes. The genotype x environment interactions were substantial for all the characters except days to 50 per cent flowering and oil content. The linear components were accounted for major portion of total G x E interactions for all the traits except total length of main raceme, effective length of main raceme and oil content. Among parents DCS-89 and JI-353 and among hybrids Geeta x PCS-124, Geeta x DCS-89, JI-353 x DCS-89, Geeta x JI-353 and JI-244 x PCS-124 were the best combinations due to their good stability coupled with high seed yield per plant. Good stability of these superior genotypes for seed yield per plant were synchronized with their stability for yield attributes. On the basis of per se performance, heterosis, combining ability as well as stability over the environments, the cross Geeta x PCS-124 was the most promising for exploitation of heterosis on commercial scale whereas, the hybrids DCS-89 x PCS-124, JI-353 x PCS-124, Geeta x DCS-89, JI-353 x DCS-89 and JI-342 x DCS-89 may be utilized for isolation of high yielding genotypes /inbred lines in the later segregating generation. ABBREVIATIONS USED BP = Better parent Cap = Number of capsules on main raceme DF = Days to flowering of main raceme DM = Days to maturity of main raceme EB = Number of effective branches per plant EL = Effective length of main raceme G x E = Genotype x Environment gca = General combining ability ND = Number of nodes up to main raceme No. = Number Pht = Plant height up to main raceme SC = Standard check sca = Specific combining ability SW = 100-seed weight TL = Total length of main racemeenYIELD AND YIELD ATTRIBUTING TRAITS IN CASTORThesis