Effects of gibberellic acid on growth and flowering of china aster (Callistephus chinesis Nees.)

Abstract

Gibberellic Acid at concentrations of 0 (control, spraying with distilled water), 10,25,50,100,250,500 and 1000 ppm were sprayed at 60 and 75 days after sowing on China aster cultivar ‘Heart of France’ to observe the effects on growth, flowering and chemical composition. The results indicated that GA3 spray at 50 ppm and above effetely increased plant height at all stages of growth, whereas 100 and 500 ppm concentrations were most effective in increasing the number of main branches. The influence of GA3 was not evident on the production of axillary branches. Flowering was accelerated considerably as a result of GA3 spray and the maximum acceleration of 52 days was obtained by 250 ppm spray. Though total flower production was not increased, the marketability of the flowers was significantly increased by GA3 sprays of 50-25 ppm as GA3 treated flowers were of better quality in terms of size (diameter), fresh weight and longevity. The total nitrogen content of leaves increased at vegetative stage in GA3 treated plants which might have contributed towards production of more branches. Similarly, sugar content in leaves at vegetative stage improved in GA3 treatments which might have helped the plants to produce better quality flowers. The flowers of the GA3 treated plants contained maximum amount of reducing and non-reducing sugars, which might have contributed towards better flower life.