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Genetic improvement through induced mutation in dahlia (Dahlia variabilis Desf.)
The per cent sprouting and survival at 15 days (%) decreased with increase in dose of gamma rays which was exhibited by all the three varieties in the same fashion. The reduction at higher doses might be attributed to genetic loss due to chromosomal aberrations and gene mutation which might be let...
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| Format: | Ph.D Thesis |
| Publicat: |
Vellayani
Department of Plant Breeding and Genetics, College of Agriculture
2017
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| Matèries: |
| LEADER | 04803nam a22001697a 4500 | ||
|---|---|---|---|
| 082 | |a 630.28 |b MAN/GE | ||
| 100 | |a Manu R | ||
| 245 | |a Genetic improvement through induced mutation in dahlia (Dahlia variabilis Desf.) | ||
| 260 | |a Vellayani |b Department of Plant Breeding and Genetics, College of Agriculture |c 2017 | ||
| 300 | |a 88 | ||
| 502 | |a MSc | ||
| 520 | 3 | |a The per cent sprouting and survival at 15 days (%) decreased with increase in dose of gamma rays which was exhibited by all the three varieties in the same fashion. The reduction at higher doses might be attributed to genetic loss due to chromosomal aberrations and gene mutation which might be lethal for sprouting and survival. A gradual decrease in plant height was recorded with increase in dose of gamma rays which was evident in data recorded at 30, 60, 90 and 120 days after planting. Reduction in vegetative growth after exposure to radiations might be due to interference in normal mitosis and frequent occurrence of mitotic aberrations, inhibition of rate of assimilation and also due to changes in auxin level or due to inactivation of auxin. The range in plant spread among the treatments showed that there was a significant reduction in plant spread at higher doses of gamma rays as compared to lower doses. This decrease was inversly proportional to the dose employed. A gradual decrease in number of branches was recorded with gradual increase in dose of gamma rays. The reduction in number of branches may be due to inhibitory effect of higher mutagenic doses of gamma rays. Leaf length and leaf width were found higher in control plants as compared to treated plants. As dose of gamma radiation increased the length and width of leaf decreased. Internodal length, thickness of internode and thickness at node were found superior in control plants than the plants treated with gamma rays in all the three varieties studied. Days to flowering however, was earlier at 5 Gy (63.89 days) as compared to control (64.94 days). As dose of radiation increased the days to flowering also increased. Number of flowers plant-1 and size of flower (cm) were inversely proportional to mutagen dose. The number of flowers got significantly reduced with increasing rate of gamma irradiation. The decrease in number of flowers per plant may be due to decrease in number of branches plant-1. Significant reduction in floret number at higher doses of gamma rays was noticed, which might be due to reduction in the vegetative growth of the treated plants and also physiological disturbances. Petal number was also reduced at doses which were high. The longevity of flower was reduced and there was disharmony of ray floret opening at higher doses. The delay in flowering resulted in a reduced longevity period both in intact and cut flower condition. In M1V1 generation Amb - white and Amb - purple produced mutants for flower colour at 5 Gy and 10 Gy dose of radiation. Flower colour mutant obtained from Amb-white variety at 5 Gy was WM1 which showed a change in colour from wood colour in control flower to yellow colour in the central disc region . In WM2 mutant in Amb-white, the central disc was enclosed by a whorl of ray florets presenting an unopened spherical appearance of ray florets in the centre. Towards the pheriphery, the ray florets were broad and arranged in a haphazard manner. The mutant from Amb-purple PM1 showed white tips with purple base, whereas control flower was single solid purple colour. Length of tuber was found to be the highest in plants treated with 5 Gy dose as compared to untreated plants. As doses were increased the tuber length showed a diminishing trend. Fresh weight, length and breadth of tubers were inversely proportional to mutagen dose. Three mutants showing prominent flower character mutations were isolated from M1V1 generation. They include WM1 showing flower colour and form variation isolated from Amb-white, WM2 showing form variation isolated from the same parent and PM1 showing colour variation isolated from Amb-purple. They were carried forward to M1V2 generation for stability screening. Both WM1 and WM2 showed a tendency to revert back to the original flower form and colour, denoting that they were not stable. PM1, the colour mutant isolated from Amb-purple, showed stable performance in M1V2 generation. Although prominent plant architecture mutations were not observed, significant size reduction at higher doses was prevalent in all the three varieties in M1V1 and M1V2 generations. | |
| 650 | |a Plant Breeding and Genetics | ||
| 700 | |a Lekha Rani C (Guide) | ||
| 942 | |2 ddc |c TH | ||
| 999 | |c 157828 |d 157828 | ||
| 952 | |0 0 |1 0 |4 0 |6 630_280000000000000_MANGE |7 1 |8 REF |9 157593 |a KAUCLV |b KAUCLV |c THESES |d 2017-12-04 |o 630.28 MAN/GE |p 173997 |r 2017-12-04 |w 2017-12-04 |y TH | ||