Determination of gamma radiation dose in mutation breeding of poplar (Populus deltoides Bartr. ex Marsh.)

Abstract

Monoculture of poplar based on few clones has led to widespread incidence of insects and diseases. Mutation breeding is considered an option for creation of new variability in the vegetatively propagated crops. In the present study, cuttings of clone L-47/88 were subjected to six doses of gamma rays i.e. 0, 10, 20, 30, 40 and 50 Gy and were planted in the field following randomized block design with four replications and plot size of 16 cuttings. The effect of gamma rays on sprouting, survival percentage, leaf and growth traits was found to be significant. The reduction in sprouting over control was maximum at 50 Gy (40.43 %) and the lowest reduction was at 10 Gy and 20 Gy (2.13 %). All cuttings of dose 40 Gy and 50 Gy were having stunted growth and experienced total mortality within 45 days after sprouting. The percent reduction in survival over control at 30 Gy was 48.05, which may be considered as LD50. The maximum values for leaf area (176.7 cm2), leaf length (15.99 cm) and leaf width (16.19 cm) were recorded in T1 (control) and relative values for T6 (50 Gy) were 45.4 cm2, 10.16 cm and 9.96 cm, respectively. The leaf blade area and plant height decreased significantly with progressive increase in dose level. The chlorophyll index was at par among all levels of gamma rays. Further studies need to be conducted for identification of positive mutants by using 30 Gy dose of gamma radiations.