GENE ACTION FOR AGROMORPHOLOGICAL AND QUALITY TRAITS IN LINSEED (Linum usitatissimum L.)
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Date
2015-08-14
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DEPARTMENT OF CROP IMPROVEMENT
Abstract
ABSTRACT
Flax (Linum usitatissimum L.) is an annual, self-pollinat¬ing, diploid (2n = 2x = 30) crop belonging to the Linaceae family with a genome size of ~ 370 Mb. Gene action for seed yield and its component traits in linseed were studied using triple test cross and line × tester analysis. The main objective was to determine the nature and magnitude of genic effects for different biometrical traits under variable environments that could support further improvements of linseed productivity using appropriate breeding methodology. The epistatic component of genetic variation detected in the present studies in the inheritance of all the yield and yield contributing traits except for plant height, technical height at Palampur (E1) and seeds per capsule in all the environments (E1, E2 and E3). Mean squares due to sums (which indicate additive component) were highly significant for all characters studied except for seeds per capsule in all the environments (E1, E2 and E3). The mean squares due to differences (which indicate dominance component) were also significant for all characters studied except for technical height at Palampur (E1) and days to 75 per cent maturity and seeds per capsule in all the environments (E1, E2 and E3). The directional element (F) was non-significant (ambidirectional) for all the traits for which dominance component was significant in all the environments (E1, E2 and E3) suggesting that the alleles with increasing and decreasing effects appear to be dominant and recessive to the same extent. Comparison of the two approaches has revealed that, in general the presence of dominance genetic variance alone with respect to seeds per capsule and additive genetic variance with respect to days to 75 per cent maturity in all the environments (E1, E2 and E3) has been revealed by both triple test cross and line × tester analysis. The parents Giza-7, Jeewan and Bhagsu were found to be the good general combiners for seed yield per plant and component traits at Palampur (E1) and pooled over the environments (E3). Further, evaluation of crosses based on combination of heterosis and SCA parameters would be more meaningful than on individual parameters. The common crosses based on both high heterotic response as well as high SCA effect in relation to GCA effects were Giza-7 × Surbhi, Lauro × Belinka-60 and KL-236 × Belinka-60 for seed yield, Giza-7 × Surbhi and Lauro × Belinka-60 for fibre yield and Chambal × Belinka-60, Jeewan × Surbhi and T-397 × Belinka-60 for oil content in pooled over the environments (E3). Two genotypes Nagarkot, and Jeewan and four crosses Ariane × F1, Giza-8 × Belinka-60, KL-244 × Belinka-60 and Nagarkot × Belinka-60 were found to be resistant to powdery mildew, rust and fusarium wilt diseases. The F2 population of the crosses between resistant and susceptible parents segregated in a ratio of 3R:1S, indicating the presence of a single dominant gene for resistance to powdery mildew in Nagarkot, Janaki and Jeewan. Information of genetic diversity and the relationship among different genotypes of linseed is of great importance for plant breeding and genetic resource management. Molecular analysis of 28 genotypes of linseed was carried out to determine the genetic relationship among them. The results suggest that primers used in this study were informative and 16 RAPD and 11 ISSR primers generated 4.5 and 5.27 fragments on an average. ISSR data revealed somewhat more clear relationships between studied genotypes and found more useful than RAPD marker data as besides more number of fragments, RAPD was unable to detect clear relationships between the genotypes. Thus ISSR markers were more informative than RAPD markers in revealing clear cut relationships of the genotypes. The results of present study indicate that the collection of 28 genotypes assessed here is having high diversity and also revealed the broad genetic base of analyzed genotypes.
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Linseed