Gamma Radiation Effects on Growth and Mutation Breeding Potential of Radish (Raphanus sativus var. Ceeta)

Abstract

A study evaluated the effects of different gamma radiation doses on radish (Raphanus sativus var. Ceeta) with the objective of to identify optimal dosages for crop improvement. Seeds were irradiated using a Cobalt-60 source, across two sequential experiments. The first experiment evaluated low doses (0, 20, 40, 60, 80, and 100 Gy), while the second examined higher doses (0, 100, 200, 300, 400, and 500 Gy) based on initial findings indicating no significant effects at lower levels. Following irradiation, seeds were germinated in nursery trays and transplanted to field plots, using a randomized complete block design with four replications. Parameters assessed included germination and survival rates, leaf morphology (length, width, and number), root dimensions (length and girth), and biomass measurements (plant weight, root fresh and dry weight). Results demonstrated that low doses (20–100 Gy) had no significant impact on germination or survival. Higher doses maintained germination rates but reduced survival from the second week onward, particularly at 400–500 Gy. Doses up to 300 Gy generally maintained or enhanced growth parameters, suggesting a hormetic response. However, doses exceeding 300 Gy significantly reduced root weight, girth, plant weight, and survival percentage, indicating radiation-induced stress. Plants treated with 500 Gy exhibited early flowering at 35 days compared to the normal 55-day period which suggest potential mutations in developmental pathways. The study concludes that doses between 200–300 Gy have potential for mutation breeding in radish, balancing genetic variation induction with plant viability. Since the LD₅₀ threshold was not reached at 500 Gy, future research should explore higher doses while evaluating biochemical traits, nutritional quality, and trait stability across generations for practical breeding applications.