GENE ACTION FOR AGROMORPHOLOGICAL AND QUALITY TRAITS IN LINSEED

Abstract

newline ABSTRACT newlineFlax (Linum usitatissimum L.) is an annual, self-pollinating, diploid (2n = 2x = 30) crop belonging to the Linaceae newlinefamily with a genome size of ~ 370 Mb. Gene action for seed yield and its component traits in linseed were studied newlineusing triple test cross and line × tester analysis. The main objective was to determine the nature and magnitude of newlinegenic effects for different biometrical traits under variable environments that could support further improvements of newlinelinseed productivity using appropriate breeding methodology. The epistatic component of genetic variation detected in newlinethe present studies in the inheritance of all the yield and yield contributing traits except for plant height, technical newlineheight at Palampur (E1 newline) and seeds per capsule in all the environments (E1 newline, E2 and E3 newline). Mean squares due to sums newline(which indicate additive component) were highly significant for all characters studied except for seeds per capsule in newlineall the environments (E1 newline, E2 and E3 newline). The mean squares due to differences (which indicate dominance component) were newlinealso significant for all characters studied except for technical height at Palampur (E1 newline) and days to 75 per cent maturity newlineand seeds per capsule in all the environments (E1 newline, E2 and E3 newline). The directional element (F) was non-significant newline(ambidirectional) for all the traits for which dominance component was significant in all the environments (E1 newline, E2 and newlineE3 newline) suggesting that the alleles with increasing and decreasing effects appear to be dominant and recessive to the same newlineextent. Comparison of the two approaches has revealed that, in general the presence of dominance genetic variance newlinealone with respect to seeds per capsule and additive genetic variance with respect to days to 75 per cent maturity in all newlinethe environments (E1 newline, E2 and E3 newline) has been revealed by both triple test cross and line × tester analysis. The parents Giza7, newlineJeewan and Bhagsu were found to be the good general combiners for seed yield per plant and component traits at newlinePalampur (E1 newline) and pooled over the environments (E3 newline). Further, evaluation of crosses based on combination of heterosis newlineand SCA parameters would be more meaningful than on individual parameters. The common crosses based on both newlinehigh heterotic response as well as high SCA effect in relation to GCA effects were Giza-7 × Surbhi, Lauro × Belinka60 newlineand KL-236 × Belinka-60 for seed yield, Giza-7 × Surbhi and Lauro × Belinka-60 for fibre yield and Chambal × newlineBelinka-60, Jeewan × Surbhi and T-397 × Belinka-60 for oil content in pooled over the environments (E3 newline). Two newlinegenotypes Nagarkot, and Jeewan and four crosses Ariane × F1 newline, Giza-8 × Belinka-60, KL-244 × Belinka-60 and newlineNagarkot × Belinka-60 were found to be resistant to powdery mildew, rust and fusarium wilt diseases. The F2 newlinepopulation of the crosses between resistant and susceptible parents segregated in a ratio of 3R:1S, indicating the newlinepresence of a single dominant gene for resistance to powdery mildew in Nagarkot, Janaki and Jeewan. Information of newlinegenetic diversity and the relationship among different genotypes of linseed is of great importance for plant breeding newlineand genetic resource management. Molecular analysis of 28 genotypes of linseed was carried out to determine the newlinegenetic relationship among them. The results suggest that primers used in this study were informative and 16 RAPD newlineand 11 ISSR primers generated 4.5 and 5.27 fragments on an average. ISSR data revealed somewhat more clear newlinerelationships between studied genotypes and found more useful than RAPD marker data as besides more number of newlinefragments, RAPD was unable to detect clear relationships between the genotypes. Thus ISSR markers were more newlineinformative than RAPD markers in revealing clear cut relationships of the genotypes. The results of present study newlineindicate that the collection of 28 genotypes assessed here is having high diversity and also revealed the broad genetic newlinebase of analyzed genotypes.