GENETIC ANALYSIS OF YIELD AND OTHER TRAITS TO UNRAVEL THE MUTAGENS-MEDIATED VARIABILITY IN ETHIOPIAN MUSTARD (Brassica carinata A. Braun)
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Date
2019-03-08
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CSKHPKV, Palampur
Abstract
The present study entitled “Genetic analysis of yield and other traits to unravel the mutagens-mediated variability in Ethiopian mustard (Brassica carinata A. Braun)” was carried out to congregate information on genetic architecture, combining ability, heterosis and inheritance of Alternaria blight resistance. The materials for the investigation comprised of 16 fixed mutant lines, three testers i.e. Jayanti, P(4)2b and their F1 (Jayanti × P(4)2b) and resulting 48 TTC hybrids. These progenies and their parents were grown in a randomized complete block design with three replications during rabi 2016-17 at the Experimental Farm of the Department of Crop Improvement, CSK HPKV, Palampur (H.P.).
Analysis of variance indicated the significance of mean squares due to genotypes for all the traits which revealed the presence of sufficient genetic variability in the existing material. Triple test cross analysis exhibited the presence of significant epistasis for all the traits except for plant height and harvest index. Further, partitioning of epistasis revealed the importance of ‘j+l’ type of epistasis for almost all the traits except for harvest index whereas, ‘i’ type interaction were non-significant for all the traits except for days to 50 per cent flowering, number of secondary branches per plant, seeds per siliqua and oil content. Relative magnitude of additive component (D) was predominant over dominance component (H) for most of the traits except for seeds per siliquae, biological yield per plant and oil content.
The line × tester analysis revealed that non-additive gene action (σ2 D) played a major role in the manifestation of almost all the traits except for days to flower initiation. The genotype P(4)2a was found to be good general combiner for seven traits followed by P22 for six traits, P74 for five traits and P36 for four traits, respectively. None of the crosses could reveal significant specific combining ability effect for all the traits. For seed yield per plant, five crosses viz., P(3)2 × Jayanti, P13b × P(4)2b, P47 × P(4)2b, P36 × Jayanti and P10b × Jayanti showed significant positive SCA effects. Heterosis was observed for almost all the characters except for harvest index. For seed yield per plant, only two crosses namely P(4)2a × Jayanti and P74 × Jayanti were found to be the best cross combinations showing heterobeltiosis and economic heterosis. To study the genetic control of inheritance of Alternaria blight resistance, three crosses viz., Jayanti × P(4)2b, Jayanti × EC-399300 and RCC-4 × EC-399300 were attempted and evaluated. However, no concrete ratio could be fitted in F2 population as disease reaction varied from moderate to high susceptibility as the available donor sources do not have high level of resistance which indicated that Alternaria blight resistance is not at least monogenic in nature. Therefore, six parameter model was used to find out the gene effects for inheritance to Alternaria blight resistance using per cent disease index (PDI) with square root transformation. Significance of A, C and D tests confirmed the presence of epistasis. Six parameters model showed significant estimates of additive [d], and non-additive [h] effects as well as all the three types of epistasis viz., additive × additive [i], additive × dominance [j] and dominance × dominance [l]. The opposite signs of [h] and [l] indicated the presence of duplicate epistasis for the inheritance of Alternaria blight resistance.
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