Determination of gamma rays induced mutagenic sensitivity of guava (Psidium guajava L.) cv. ‘Lalit' and ‘Shweta’

In the present investigation, seeds of guava cv. ‘Lalit' and ‘Shweta' were irradiated with different dosages of gamma rays ranging from 25 to 150 Gy using the ⁶⁰Co source to examine its effects on morphological and physiological traits. The LD₅₀ value calculated on the basis of germination percentage of irradiated seedlings using probit curve analysis, was 57.81 Gy and 57.42 Gy for ‘Lalit' and ‘Shweta', respectively. Seed germination and growth parameters viz., plant height, internode number, internodal length and leaf dimensions had negative correlation with gamma irradiation., while the parameters, number of leaves and branches experienced the hormetics radiostimulant effect at lower dosage (up to 50 Gy), but a marginal reduction was observed at higher dosages (125–150 Gy). Reduction in stomatal number with increased stomatal size were observed in the mutant populations. With ascending irradiation doses, a marginal signifcant reduction was observed in leaf chlorophyll content. The results of this study will allow implementation of mutagenesis-based genetic improvement programmes in guava and, serve as a morphological and physiological marker to identify some desirable mutants at early stage.