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Wheat Information Service
Number 74: 17-21 (1992)


Radioprotective effect of gibberellic acid in triticale

V. K. Khanna

Department of Plant Breeding, G. B. Pant Agrivarsity, Pantnagar-263145, U. P., India


The damage caused by ionizing radiations has been reported to get reduced by pre-treatment with many chamicals. Thiourea and dimethly sulphoxide has been found to reduce chromosomal damage in various species of plants (Wolff 1954, MikasIsen 1955, Riley 1957, Kaul 1969). Among the plant growth regulators gibberellic acid (GA_3,) is known to reduce gamma radiation effects on plant growth in maize (Gaur and Notani 1960), wheat (Habar and Luipold 1960, Uppal and Maherchandani 1988), barley (Maharchandani and Vasudeva 1984), and Avena fatua (Maherchandani and Vasudeva 1985). Gibberellic acid has been reported to increase peroxidase activity (Jain et al 1980), due to which surviving paroxy radicals may be eliminated such that the resultant detectable damage is less (Alper 1979). Present study deals with the effects of a low concentration (10 ppm) of GA₃ on the seedling growth, cytological damage and peroxidase activity in the gamma-irradiated triticale seeds.


Materials and Methods

Seeds of triticale variety UPT 78268 with a moisture content of 10 + or - 1 per cent were irradiated with 10-40 kR gamma rays. These were soaked either in water or in 10 ppm GA₃ soultion for 16 hours. The seeds were then removed from the solutions and germinated in petri-dishes on filter papers soaked with water or GA₃ soulution. There were three plates per treatment, each containing 25 seeds.

Root tips were fixed in acetic acid-ethanol (1:3) for cytological studies after 36 hours. After 24 hours in the fixative, these roots were transferred to 70 per cent alcohol and kept in a refrigerator. Root tips were hydrolysed in 1N HCl for 10 minutes, and stained and squashed in 1 per cent acetocarmine. Frequency of abnormal anaphases was estimated in each treatment from 500 anaphase cells scored from 5-6 slides from 10 root tips. Mitotic Index was estimated from 1200-1900 cells. Seedling height was recorded on 5 day old seedlings. For peroxidase activity 0-6 days old seedlings were selected and dried with a blotting paper. One gram material was homogenized for 60 seconds in 5 ml of precooled 0.9 per cent NaCl, in a precooled mortar kept in an ice-bucket. The homogenate was centrifuged for 30 minutes at 12,000 rpm and the supernatant was collected. The crude enzyme extract (0.1 ml) was diluted in 5 ml. of 50 mM Na₂CO₃-50 mM NaCI buffer having a pH of 6. The enzyme was assayed by the method of Karege et al (1982). Na-K phoshate buffer (40 mM), pH 6.1 containing 8 mM guaiacol and 2 mM H₂O₂ was added to the enzyme mixture. The increase in absorbance due to oxidation of guaiacol in the presence of H₂O₂ and enzyme was recorded at 470 nm after 2 min. Data was recorded on three replications.

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