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Please use this identifier to cite or link to this item: http://www.erepo.iihr.ernet.in/handle/123456789/344

Title: Studies on the genetics of yield and quality characters in bulb and seed crop of onion (Allium cepa L.)
Authors: R, Veere Gowda
Guide/Chairperson: C S, Pathak
Keywords: Genetic
bulb and seed
Issue Date: 1988
Year of Submission: 1988
Abstract: The main objectives of the investigation were to study extent of heterosis, combining ability and nature of gene action in respect of twenty five characters in bulb crop and nine characters in seed crop of onion using the diallel technique. The variance due to treatments were significant at one percent level for all the traits in both bulb and seed crop. Variance due to parents were highly significant in respect of height of the plant, earliness, split bulbs, dry weight of leaves, fresh and dry weight of the bulb, ten bulb weight, marketable and total bulb yield, double centres, rings per bulb, TSS, storage rot, sprouts and storage loss in weight for the bulb crop. In seed crop, variance were highly significant for days to flower initiation, height of umbel stalk, diameter of umbel, seed yield per plant and seed yield per hectare, however, percent dry matter content was significant at five percent level only. The variance due to hybrids was highly significant for height of the plant, earliness, split bulbs, dry weight of leaves, fresh and dry weight of the bulbs, ten bulb-weight, marketable and total bulb yield, double centres, firmness of the bulb, storage rot, sprouts and loss in the bulb crop where as in seed crop there were significant difference for days to flower initiation, height of umbel stalk, diameter of umbel, seed yield per plant and seed yield per hectare. The extent of heterosis estimated over mid, better and best parents revealed superiority of some outstanding F1s over best parent; for the number of leaves per plant, three hybrids i.e., 2x5, 2x7 and 3x7 were best. For the equatorial diameter of the bulb, the crosses 1x4, 5x 9,6x7, 6x8 and 9x10 were significantly superior over the best parent; for the polar diameter of the bulb, crosses 2x5 2x7, 2x10, 3x10, 4x9, 4x10, 8x10, 8x11 and 9x10 were significant over the best parent. The crosses 1x8, 1x9, 2x9 and 10x11 showed significant heterotic effects over the best parent for dry weight of leaves, the crosses that expressed superiority over best parent for fresh weight of bulb were 4x9 and 4x11. In seed crop the outstanding F1s over best parent were seen in the cross 2x10, for diameter of umbel stalk; 5x6 and 5x11 for diameter of umbel, the crosses 2x8, 3x10, 5x9, 6x7, 8x11, 9x10 and 2x10 followed by several other crosses for seed yield per umbel; 2x8 and 2x9 for seed yield per plant: 2x8, 2x9, 9x11, 2x10 and 4x7 for yield per hectare and none of the crosses were significantly superior for rest of the characters. The variances due to GCA were greater than SCA for all characters in bulb in seed crop; except for the character seed yield per umbel where in SCA variance was greater. A comparison of gca effects revealed that none of the parents were good in respect of all the characters. However, parent 1 (IHR 52-80) was found to have best performance as it has significant gca effects for 12 characters followed by parent 6 (IHR- 68) for 10 characters, parent 2 (IHR-60-94), 4 (IHR-400), 5(IHR 121-26), 7(IHR 399), and 8 (IHR-6). Best parental combination i.e., parent 2 (IHR-60-94) and 8 (IHR-6) were found to be top combiners for most of the characters (14) followed by the combination, parent 1(IHR 52-80) and parent 11(IHR56-198) for 11 traits each. All these parents have additive genetic variance for these traits which could be utilized for improving these characters through selection. For the exploitation of heterosis; the specific combining ability is important. On the whole in most of the characters studies, all the three types of generation were observed. Under such situation, improvement in such characters may be expected through standard selection procedures which may first exploit additive genetic variance simultaneously the dominance variance should be concentrated. For this, reciprocal recurrent selection breeding procedures seem to be the best method to meet the requirements as it will utilize simultaneously all the 3 kinds of gene effects.
URI: http://www.erepo.iihr.ernet.in/handle/123456789/344
University in which they received their degree: University of Agricultural Sciences, Bangalore
Degree Level: Ph.D

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