Cytoplasmic male sterility CMS based heterosis and gene action studies in cauliflower Brassica oleracea L var botrytis L

Abstract

The present investigation was undertaken to assess the combining ability, nature and magnitude of gene action and to ascertain best heterotic combinations for morpho-physiological, yield and yield contributing and quality traits. Forty eight cross combinations developed by crossing eight CMS lines and six diverse testers in Line × Tester fashion were evaluated along with four standard checks in randomized complete block design with three replications at the Vegetable Research Farm, CSK HPKV, Palampur and HAREC, Bajaura, Kullu during winter 2017-18. Visual, morphological (Ward s method) and molecular characterization (SSRs) were employed to assess the diversity in parental materials. Out of 35 SSRs, 28 were found to be polymorphic and PIC value ranged from 0.17 to 0.54 with an average of 0.37. The PCoA, PCA and factor analysis delineated the CMS lines into two groups as mid-maturity (CaYCMS-1, CaYCMS-2, CaYCMS-3, CaYCMS-4 and CaYCMS-5) and late group (CaYCMS-6, CaYCMS-7 and CaYCMS-8) CMS lines. All the CMS lines showed similar performance as that of their maintainers for seedling, floral and seed traits. Results of combining ability were discussed by analysing the data in all three possibilities as Experiment I (All CMS lines and testers), Experiment II (5 Mid-late group lines and testers) and Experiment III (3 Late group lines and testers). The bifurcation of experiment reveals the importance of late group lines in terms of earliness and mid-group lines for yield and related traits when analysed for GCA. Thus lines and testers showing good GCA, crosses with good SCA and heterosis in Experiment II and Experiment III were given prime importance. The analysis of variance indicated significant differences among genotypes for most of the traits in both the experiments under all the environments, exhibiting wealth of variability. Location × genotype interaction was significant for most of the traits which indicated a definite role of environment on the performance of genotypes. The line × tester analysis revealed sign