EFFECT OF PHYSICAL AND CHEMICAL MUTAGENS ON MORPHOLOGICAL BEHAVIOUR OF PAPAYA CV. 'ARKA PRABHAT

Abstract

The present investigation on “Effect of physical and chemical mutagens on the morphological behaviour of the papaya variety 'Arka Prabhat' was carried out at the CCS Haryana Agricultural University in Hisar during the 2020–21 period. The experiment was Completely Randomized Design (CRD) with twelve treatments and three replications. In papaya, plant height represents a significant problem at the time of harvest since tall plants are very susceptible to wind damage; nevertheless, no dwarf gynodioecious cultivar is currently available. In order to obtain variability for desirable morphological traits in the 'Arka Prabhat' variety, a mutation breeding programme was started using both physical (gamma rays) and chemical (ethyl methanesulfonate, EMS) mutagens. The treatments included T1 at 100 Gy, T2 at 200 Gy, T3 at 300 Gy, T4 at 400 Gy, T5 at 500 Gy and T6 at 600 Gy for gamma radiation, and T7 at 0.2%, T8 at 0.4%, T9 at 0.6%, T10 at 0.8% and T11 at 1.0% for EMS, with T12 serving as the untreated control. The seeds of 'Arka Prabhat' were obtained from freshly ripe fruit after controlled pollination and were used for the mutagenic treatments. The LD50 was determined to be at T4 (400 Gy) for gamma rays and at T9 (0.60% EMS) for the chemical mutagen. The progeny from treatment T12 (control) showed significantly better values for germination percentage, the number of days taken for germination, survival percentage, the number of leaves per seedling, shoot length, root length and seedling height when compared to the progeny obtained from the mutagen treated plants. The seedlings derived from treatment T1 (100 Gy) had the highest total leaf chlorophyll content, whereas those from treatment T4 (400 Gy) irradiated plants had the largest trunk circumference and canopy spread. The progeny from treatment T8 (0.4% EMS) had the lowest plant height and dwarf plants were specifically noted at this treatment. No significant differences were found among the treatments with respect to the non-numerical morphological characteristics- the type of branching, the number of branches and leaf type and no morphological abnormalities were observed in any of the treated progenies.