Effects of Acute Gamma Irradiation on Adventitious Plantlet Regeneration and Mutation from Leaf Cuttings of African Violet (Saintpaulia ionantha)

Abstract

Leaf cuttings of Saintpaulia ionantha (African violet) cv. Optima Hawaii, purple flower were acutely irradiated by gamma-rays with the doses of 0, 10, 20, 40, 60, 80 and 100 gray (Gy) to induce mutation. Irradiated leaves (M1V0) were planted in plastic trays containing peat moss medium and were
placed in a shaded greenhouse. A number of adventitious plantlets per irradiated leaf (M1V1/M1V0) were recorded. M1V1 plantlets were transplanted and were grown to flowering according to the standard African violet culture. The characters investigated in M1V1 plants were the number of leaves per plant, plant canopy width, the number of inflorescences per plant, the number of flowers per inflorescence, flower size and mutated characters. The results showed LD₅₀₍₆₀₎ to be 56 Gy. The number of plantlets per leaf decreased as radiation doses increased. No survived leaves were observed at doses higher than 80 Gy. In M1V1 generation, averaged width of plant canopy and the number of flowers per inflorescence
were not significantly different whereas the number of inflorescences per M1V1 plant and flower size were significantly different. Mutation characters observed were – changes in leaf colour, leaf margin, leaf thickness, flower colour, flower size, flower form and plant type. Mutation rate of M1V1 plants increased as radiation doses increased. Seven mutants with desirable characters were selected.