Genetic Study of Grain Yield and its Contributing Traits in Barley (Hordeum vulgare L.) under Normal and Limited Moisture Conditions

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The present investigation was conducted to analyze combining ability, components of genetic variance, heterosis, heterobeltiosis, inbreeding depression and drought stress tolerance in ten genetically diverse parents viz., BH 946, RD 2592, DWRUB 64, DWRB 137, PL 426, PL 419, RD 103, RD 2035, RD 2052 and RD 2508 in barley (Hordeum vulgare L.) in two environments viz., E1 – normal irrigated and E2 – limited moisture conditions at Research Farm, Rajasthan Agricultural Research Institute (Sri Karan Narendra Agriculture University, Jobner), Durgapura, Jaipur. These parents were crossed in half-diallel mating design (excluding reciprocals) in rabi 2018-19 and their F1 seeds were advanced in summer 2019. The evaluation trial was conducted in rabi 2019-20 in which 10 parents along with their 45 F1‟s and 45 F2‟s were evaluated in a randomized block design with three replications. The observations were recorded for days to heading, days to maturity, plant height, number of effective tillers per plant, flag leaf area, peduncle length, number of grains per spike, number of spikelets per spike, spike length, biomass per plant, 1000-grain weight, grain yield per spike, grain yield per plant and harvest index. The significant differences among the parents and generations in both the environments for all the studied characters suggested the presence of sufficient genetic variability. Significance of GCA and SCA for all the studied characters in both the generations indicated the importance of both additive and non-additive gene action. The GCA/SCA variance ratio (predictability ratio) indicated the preponderance of non-additive gene action. An overall assessment showed that the parents RD 2508, RD 2052 and PL 419 appeared as good general combiners and the crosses DWRUB 64 x RD 2508 and RD 2592 x PL 419 appeared as good cross combinations for grain yield per plant and its contributing traits in both the environments. Evaluation of the genetic components of variance manifested that both additive (D) and dominance (H1 and H2) components were significant for all the studied characters which indicated that both components were operating in the expression of the traits. The results of graphical analysis revealed partial and over dominance for different characters in normal irrigated and limited moisture conditions. The dispersed array point indicated the presence of satisfactory diversity among the parents. Sufficient degree of heterosis and heterobeltiosis were observed for all the studied characters. The cross DWRUB 64 x RD 2508 in E1 (normal irrigated) and DWRB 137 x RD 2052 in E2 (limited moisture) exhibited desirable heterosis and the cross PL 419 x RD 2052 in E1 (normal irrigated) and PL 419 x RD 2508 in E2 (limited moisture) exhibited desirable heterobeltiosis for grain yield per plant and its attributing characters. An overall assessment on the basis of per se performance, SCA effects and heterosis, revealed that the cross RD 103 x RD 2508 in E1 (normal irrigated) and DWRB 137 x RD 2052 in E2 (limited moisture) environment were emerged as good cross combinations for grain yield per plant and its attributing characters. Hence, these crosses may be considered desirable under particular environment and may be used further in specific breeding programmes. The result of drought susceptibility index (DSI), it could be visualized that parents DWRUB 64, BH 946, RD 103 and RD 2592, were found the most desirable for most of the characters. Among the crosses, RD 2592 x PL 426 and PL 426 x RD 103 were found more desirable as they possessed high drought tolerance for most of the studied traits across the generations and could be used as promising breeding material for the development of new drought tolerant varieties. An overall assessment of the result of this study advocated that restricted recurrent selection, diallel mating design and bi-parental mating could be used as effective and alternative breeding approaches for the development of superior genotype and appreciable improvement of barley in forthcoming years.