Early Generation Selection of Lines Suitable for Yield and Earliness in Cauliflower (Brassica oleracea var. botrytis L.)
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Date
2017-08
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Department of Horticulture (Vegetable and Floriculture), BAU, Sabour
Abstract
Cauliflower is a thermo-sensitive cool season vegetable crop. On the basis of temperature requirement to curd initiation the crop is grouped into early, mid and late cauliflower. The hybrid is most important as because of uniform maturity, compacted curd, and resistant to environmental stresses. Very few hybrids are available for cultivation in early group of cauliflower. Inbreeding programme in cauliflower is tedious, labour intensive and costly that slower down the effectiveness of hybrid breeding programme. To reduce these problems, Jenkin (1935) had been proposed a technique to early generation testing in genotypes during inbreeding based on GCA estimation. In the present experiment 19 S2 generation lines were tested for combining ability analysis using line x tester mating design with two testers namely Sabour Agrim and Pusa Kartik Sankar. The experiment was laid out in Randomised Block Design with a spacing of 50x 50 cm in two replications with two dates of planting. The analysis of variance revealed the existence of significant genetic variability among the treatments. The MSS for parent vs. cross was also found significant which depicted that existence of heterosis among the cross for the traits under study. The characters net curd weight (NCW), harvest index (HI), marketable curd weight (MCW) and biological weight (BW) were found to be highly heritable and high expected genetic advance indicated that the selection of parental line for these traits could be effective. Pooled analysis of GCA recorded Hzp 108 (-7.22) and Sel 31-1 (-4.97) were significantly negative for D50 % CI; usefulness for the development of early maturity hybrid. However Hzp 106 (112.23), Hzp 101 (80.52) and Hzp 111 (44.70) were found to be good general combiner for NCW that means these genotypes will be useful for the development high yielding hybrids. Cross combination Hzp 106 x PKS (48.02 %), Sel 332 x PKS (33.68 %) and SA-1 x SA (37.05 %) were recorded positive significant relative heterosis and heterobeltiosis for NCW. In the present study, the high D2 value indicated a high degree of genetic diversity among the genotypes. Pooled data analysis for morphological diversity revealed that all the 21 genotypes were grouped into four groups or clusters Cluster I includes 14 lines, cluster II includes 5 lines, cluster III and cluster IV include single genotype in each cluster. The highest inter cluster distance (580.42) was observed in between cluster I and cluster IV followed by cluster I and III (438.36), cluster I and II (180.79). On the basis of molecular diversity analysis, similarity values for all cauliflower genotypes were ranged from 0.50-0.90. The high ranges of similarity coefficient indicated the presence of narrow genetic variability. PIC value ranged from 0.121-0.290. All the SSR primers showed monomorphic band except SSR 73 and SSR 110. From the above findings it can be concluded that among the 19 segregating lines Hzp 108 and Sel 31-1 would be desirable for breeding cauliflower hybrids for earliness and lines Hzp 106 and Hzp 101 would be effective to producing the heterotic hybrids for net curd weight.
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