Influence of gamma irradiation on germination traits, growth and biochemical attributes of dragon fruit (Selenicereus monacanthus)

The aim of this research is to assess the effectiveness of gamma irradiation in developing genetic variability in dragon fruit by influencing biochemical attributes. Seeds of dragon fruit were exposed to 100, 200, 300, 400 and 500 Gy γ-radiation using Co-60 source. Highest germinability, mean germination time, mean daily germination, vigour index and growth rate were observed in untreated seeds, however these traits were relatively less affected at lower irradiation level (up to 200 Gy). An irradiation level of ≥ 400 Gy severely affected germination traits and seedling growth and consequently 441 Gy irradiation level was considered as the lethal dose (LD50) for dragon fruit. Photosynthetic pigments, protein content and nutrient content were highest in untreated seedlings and moderately high up to 200 Gy. Findings demonstrated that the concentration of biochemical markers for abiotic stress tolerance viz. proline, phenol, flavonoid and antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase), were significantly high at 200 Gy irradiation level. Hence an irradiation dose of 200 Gy may be considered as an optimal for induced mutagenesis for abiotic stress tolerance in dragon fruit with the least possible unintended damage to seedling growth traits. The findings provide valuable insights into the efficient utilization of γ-irradiation in expediting the development of abiotic stress-tolerant mutant lines of dragon fruit.