Variability and genetic diversity among selfed lines (S1) of onion (Allium cepa L.)

Abstract

Onion is a highly cross-pollinated crop, high variability could possibly come from traditional seed production by out-crossing or by open pollination and it could lead to more diversity and variation. The high phenotypic, genotypic variation coefficients reveal high-quantifiable variation of traits in S1 lines. Selection of lowest premature bolting and split bulbs producing genotypes, least incidence of purple blotch incidence and thrips incidence with the highest weight of ten bulbs and maximum plot yielding genotypes were more appropriate for genetic improvement of onion. The traits aided the yield witnessed high traits heritability (h2) and maximum genetic-advance-mean (GAM) and isolation of S1 lines in terms of selection indices fixed for higher values of measurement. Whereas traits like premature bolting, split bulbs, purple blotch incidence, thrips incidence and were selected at least values although these traits were high heritability (h2) and GAM could contribute for additive-gene-action and hence it indicates the straight mass selection be more effective for genetic improvement of onion genotypes or lines. The genetic distance was highly flanked by Cluster-II and –IV groups and was highly divergent. Hence, the selection of parental lines from these groups is more appropriate for traditional heterosis breeding.