Effect of irradiation on the dendrobium hybrid Emma White x Banyat Pink

As a part of the crop improvement programme, mutation breeding was attempted in certain dendrobiurn hybrids using gamma rays. The protocorms produced from the hybrid seeds obtained from the cross Emma White x Banyat Pink were subjected to irradiation using gamma rays under in vitro conditions. The various doses of gamma rays used were 10 Gy, 20 Gy, 30 Gy, 40 Gy, 50 Gy and 60 Gy. Time taken for differentiation of leaf as well as for shoot and root formation was more in the irradiated cultures. Irradiation reduced the height of the plants and resulted in broader leaves with dark green colour. Plants, obtained by irradiation at lOGy and 30 Gy doses were got established in the field. Good vegetative growth could be noticed in these mutants. Flowering was observed in the 30 Gy treated plants 16 months after planting. The time taken from spike emergence to flowering was 38 days which was more or less same as that of Emma White. Good sized florets (7 em x 7 cm) were noticed showing a trend towards Banyat Pink. The time taken from emergence of spike to complete wilting of all the florets was 39 days which was also similar to that of Banyat Pink. The mutant had seven florets per spike, compared to amean of 5.7 in Banyat Pink and 7 in Emma White. The mutants are under further evaluation.