Abstract

                                Ten aggregatum onion lines (Allium cepa L. Var, aggregatum Don) a were crossed with three testers in the line X tester method to get 30 crosses and to choose suitable: combiners and best hybrid combination for exploitation of hybrid vigour. The study revealed that the lines P1 and P10 and tester T1 were found to exhibit high mean expression and high gca effect for yield and yield components indicating their use as appropriate parents in a crossing programme for further accumulation of favourable genes through recombinations. The hybrids P1 x T1 and P10 x T1 were found to be desirable for the purpose of exploitation of hybrid vigour because of combined expression of high mean, heterotic expression. sca effect and also the parents involved possessed high expression of gca effects, Plant height. number of leaves, number of bulbs, weight. of plant. shape index and Tss were governed by non-additive genetic factors suggesting that these traits could be improved through heterosis breeding. The role of additive genetic factors was observed for weight of bulbs and days to maturity.

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