Gamma-rays induced morphological changes in pot marigold (calendula officinalis)

Three years mutagenesis programmes were carried out using physical mutagens (gamma rays) on calendula. Pre-soaked three sets of 100 seeds were irradiated with 2.5, 5 & 7.5 KRD of gamma rays at N.B.R.I., Lucknow in Feb., 2007. A set of 100 untreated seeds was used as control. Reduction in survival rate, days to flower, fresh weight, was observed after irradiation and with increase in exposure of gamma rays. In M1generation, significant increase in plant height at 2.5 KRD & stunted growth of plants at 5 KRD gamma irradiation was observed. Morphological abnormalities in leaf and plants with abnormal leaves increased with increase in exposure of gamma rays. In case of Calendula the intensity of inhibition increased with increasing exposures though lower exposure in some cases was stimulatory. Cent per cent mortality was recorded in plants treated with 5 and 7.5 KRD gamma rays and eliminated from population at the end of first year. On the basis of present observation it may be concluded that 2.5 KRD dose of gamma rays are suitable for induction of somatic mutation in Calendula.