GAMMA-IRRADIATION RESPONSE OF CASSAVA (VAR. UBI KUNING)

Abstract

Cassava (Manihot esculenta) is a key staple crop in tropical and subtropical regions, renowned for its ability to thrive in poor soils and withstand drought conditions. In Malaysia, cassava cultivation faces challenges such as low genetic diversity, susceptibility to pests and diseases, and limited yield improvement due to reliance on traditional breeding methods. Despite its economic importance, traditional breeding methods in cassava are challenged by complex polyploid genome and predominantly vegetative propagation. This research aimed to evaluate the acute radiosensitivity of cassava var. Ubi Kuning to gamma irradiation as a preliminary step toward enhancing genetic variability for mutation breeding programs. In this study, evaluation of the acute radiosensitivity of cassava cuttings to gamma irradiation, using doses of 0 (control), 5, 10, 15, 20, 25, 30, 40, 50, and 60Gy was conducted. The cuttings were irradiated with a gamma irradiator (Biobeam GM8000) using Caesium-137 as the source, and subsequently planted in polybags in a glasshouse. The survival data indicated an LD₅₀ of approximately 33Gy whilst plant height data showed a GR₅₀ of approximately 28Gy. The results show that as the gamma radiation dose increases, both data of the survival and growth of cassava decrease, demonstrating the plant's sensitivity to gamma irradiation. The findings suggest that doses around 28-33 Gy induced significant genetic variability while maintaining sufficient viability for mutation breeding programs. This study emphasizes the importance of optimizing irradiation doses as a foundation for developing improved cassava cultivars through mutation breeding.