ABSTRACT

This study was carried out to investigate the effects of different X-ray irradiation doses on the vegetative, ornamental and some molecular attributes of African marigold (Tagetes erecta L.) plant. The seeds were subjected to various X-ray doses (0mGy, 5mGy, 10mGy, 15mGy, 20mGy, 25mGy, 30mGy and 35mGy). Treated seeds were planted on sand filled pots and they were arranged under shade house condition in randomized complete block design (RCBD) with three replications for each treatment and each replication contained 10 seeds. Emergence percentage and survival percentage of the seeds were recorded continuously for fourteen days from the first day of emergence. After close examination of the sown seeds for fourteen days, it was observed that X-ray doses above 20 mGy proved lethal to the seeds, hence seeds treated with such higher doses (25mGy, 30mGy and 35mGy) recorded no seedling emergence or germination. Reduction in emergence percentage and survival percentage was observed after irradiation and with increase in X-rays dose. The stimulatory effect of x-ray irradiation was observed at 10mGy and 15mGy in almost all the characters. Contrastingly, the high mutagenic dose of 20mGy substantially decreased all the vegetative parameters and flowering parameters as compared to the control. On the basis of the present observation, it may be concluded that X-ray irradiation of 10mGy and 15mGy could induce variability and enhance vegetative growth and flowering of African marigold (Tagetes erecta).. Thus, it can be recommended that the treatments with lower X-ray doses at 10mGy and 15mGy be adopted for improving growth and flowering parameters of African marigold (Tagetes ereta) plants. DNA was isolated from two weeks old leaves of the plant samples. The DNA of the African marigold samples were assessed for their genetic diversity using ISSR markers. A dendrogram that identified two main clusters was generated using UPGMA method of clustering, and three main sub clusters were obtained. The treated samples were aligned against the untreated samples using ClustalW multiple sequence alignment. The analysis revealed the presence of various forms of mutation. A total of 50 mutations were recorded.