Genetic Architecture of Grain Yield and its Contributing Characters in Pearl millet [Pennisetum glaucum (L.) R. Br.] Under Varying Environmental Conditions (SKNAU)(RARI)(PhD)

The present investigation was under taken to the study of combining ability, component of genetic variance, heterosis and heterobeltiosis in pearl millet [Pennisetum glaucum (L.) R. Br. ], for grain yield and its contributing characters, performing diallel analysis following Griffings (1956a) Method-II, Model-I and Hayman’s (1954b) approach. For this purpose 10 genetically diverse inbreds viz., J2340, MIR-525-2, RIB-192, RIB-494, RIB-3135-18, RIB-57, RIB-335/74, HBL-11, H77/833-2-202 and G.77/107 and 45 F1’s resulting through diallal among inbreds excluding reciprocals were grown at Rajasthan Agricultural Research Institute Farm, Durgapura, Jaipur in randomized block design with three replications under three environments (created by date of sowing) during kharif season, 2015. Analysis of variance revealed significant differences among the progenies for most of the characters indicating sufficient genetic variability. The environment wise combining ability analysis revealed significant difference for GCA and SCA variance for most of the characters indicating both additive and non-additive gene effects in the genetic control of all the traits. The GCA/SCA variance ratio showed preponderance of non-additive gene action for all the characters. Genetic component analysis revealed that, both additive (D) and dominance (H1 and H2) components were significant for all the characters, except additive (D) component in days to 50% flowering and dry fodder yield in E2 & E3 and days to maturity in E2, productive tillers in E3. plant height, biological yield and grain yield per plant in all the the environments. However, relative magnitude of dominance component was higher than additive component for all the characters indicated preponderance of dominant gene action. Narrow sense heritability estimates were low (productive tillers per plant) to high (harvest index and Fe content). * Ph. D. student, Division of Plant Breeding and Genetics, Rajasthan Agricultural Research Institute,(Sri Karan Narendra Agriculture University), Durgapura, Jaipur * Thesis submitted in partial fulfillment of the requirement for the degree of Ph.D. (Ag.) in Plant Breeding & Genetics under the supervision of Dr. L.D. Sharma, Professor, Division of Plant Breeding & Genetics, Rajasthan Agricultural Research Institute, (Sri Karan Narendra Agriculture University), Durgapura, Jaipur The graphical analysis indicated the presence of partial, complete and over– dominance for different traits. The parents RIB-57, RIB-192 and RIB-335-74 possessed more dominant genes while, J-2340 and H-77/833-2-202 possessed more recessive genes for grain yield and related traits under all the environments. Heterosis and heterobeltiosis was observed for all the traits. The most heterotic crosses for grain yield across the environments and related traits were P2 x P5, P2 x P6, P2 x P7, P4 x P6, P5 x P8, P5 x P9, P5 x P10, P6 x P7, P6 x P10 and P7 x P9. These crosses were considered desirable as these may through transgressive segregants in higher frequency in succeeding generations. The crosses have high SCA effects involving good x good general combiners were P1 x P2, P2 x P5, P2 x P6, P2 x P7, P4 x P7, P5 x P9, P6 x P7 and P7 x P9. All these offer good promise for improvement of grain yield through conventional breeding methods. As regards to GCA effects and per se performance, the parents RIB-3135, RIB-335/74, MIR-525-2 and RIB-192 emerged as good general combines for grain yield and contributing traits. Top parents and crosses on the basis of per se performance; GCA & SCA effect and heterobeltiosis were observed. Among the parents, RIB-3135-18 followed by RIB-335/74 in all the environments and crosses P5 x P9 in all the environments, P4 x P6 in E1, P5 x P10 & P1 x P2 in E2 and P6 x P7 and P2 x P6 in E3 were found best for grain yield and related traits. Conclusively, on the basis of higher SCA effects the F1’s may be used to developed restorer/inbred lines and parents may be used in further, breeding programmes. It has been suggested that, recurrent selection, diallel selective mating, biparents mating and multiple crosses could be effective breeding approaches for developing inbreds, composite/synthetic and hybrid varieties from potential breeding material in the present study. cktjk 1⁄4isfulsVe XykWde 1⁄4,y-1⁄2 vkjczk-1⁄2 esas nkuss dh mit ,oa lEcfU/kr xq.kkass dh fofHkUu okrkoj.k esa vkuqokaf’kda lajpuk jkts’k pUn thrjoky* MkWW,y-Mh'kekZZ** 1⁄4'kks/kdrkZ1⁄2Z 1⁄4eq[; lgykdkj1⁄2