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ThesisItem Open Access Induction of mutagenesis in gladiolus through gamma irradiation(Punjab Agricultural University, Ludhiana, 2017) Dogra, Neha; Dhatt, K. K.The present investigations entitled “Induction of mutagenesis in gladiolus through gamma irradiation” was undertaken at research farm, Department of Floriculture and Landscaping, Punjab Agricultural University, Ludhiana, during 2014-17. The experiments were conducted to induce variability in gladiolus through gamma irradiation under in vitro and in vivo conditions. The corms of gladiolus variety ‘Punjab Glance’ and ‘Sylvia’ were irradiated with different doses (0, 50,100,125,150 Gy) of gamma rays and planted in October at a spacing of 30x20 cm. The maximum survival per cent, sprouting per cent, plant survival, plant height and leaf number were reported to decrease with the increase in gamma rays dose above 100 Gy. The corms of ‘Punjab Glance’ treated with lowest dose at 50 Gy sprouted after 15.29 days and the same variety at 150 Gy took 23.15 days to sprouting. Maximum spike lengths, florets per spike, floret size were recorded in corms treated with 50 Gy. The shortest spikes with lowest number of florets in small size were recorded at 150 Gy. The corm multiplication in terms of corm and cormels per plant was found to reduce with increased dose of gamma rays. The leaf abnormalities were observed in terms of changes in leaf shape, leaf size, and leaf margin and leaf apex. Total abnormalities in floral characters were higher in 150 Gy. Treatment of corms at 100 Gy resulted in bud fasciation and asymmetrical development of spike in both the varieties. Five mutants were isolated from variety ‘Punjab Glance’ for flower colour under in vivo treatment, one at 100 Gy, two at 125 Gy and two at 150 Gy. The nodal buds of both varieties were raised in MS medium and bud clumps were irradiated with different doses of gamma rays (Co60) 0, 5, 8, 10 and 12 Gy. Irradiated explants were then cultured aseptically on MS basal medium supplemented with 5 mg/l (BAP) + 2mg/l (IBA) and agar-agar to induce shoot and root proliferation. It took 14.27 days for shoot formation, 15.10 days for root and 62.33 days for cormel development at 8 Gy dose. The maximum shoot length (6.19 cm), root length (8.01 cm) and maximum number of shoots and roots per callus were recorded at 8 Gy dose. The gamma rays doses of 5 and 8 Gy were found to be optimum for the induction of mutagenesis under in vitro in gladiolus variety ‘Punjab Glance’ and ‘Sylvia’ with respect to plant sprouting and survival of plant raised from cormels. The cormels raised through in vitro after gamma irradiation were planted in the field and evaluated for morphological parameters. One cormel produced small cormlets within 60 days in both varieties. This study developed a mutagenesis protocol that could be used to develop novel colour mutants in gladiolus.