FRUIT MATURATION STAGE AND GA3 IN PAPAYA SEED GERMINATION

Abstract

The achievement of uniform seedlings, capable of establishing a profitable stand, is fundamental for growing papaya successfully. Accordingly, studies related to fruit maturity, dormancy breaking, and physiological quality of seeds can be of great importance for producers of fruits and seeds. Papaya (Carica papaya L.) hybrid group ‘Tainung 01’ seeds germination and seedlings vigor were studied as a function of fruit maturation stage (semi-mature and mature), combined with immersion of the seeds, for four hours, in different concentrations of giberelic acid - GA₃ (0 mg L^-1, 250 mg L^-1, 500 mg L^-1, and 1,000 mg L^-1). A completely randomized design was used, disposed in a 2x4 factorial scheme, with four replications. There were significant effects of the interaction among the factors studied for all variables. The seeds, regardless of fruit ripeness stage, did not germinate in the absence of GA₃. Seeds from semi-mature fruits showed higher germination percentages than those from mature fruits, when soaked in solutions of 250 mg L^-1 and 500 mg L^-1 GA₃. For seeds treated with 1,000 mg L^-1 GA₃, the largest germination percentage was observed in seeds from ripe fruits. The results allowed us to conclude that fruits at semi-mature stage were more appropriate to supply seeds for seedlings. The immersion of seeds from semi-mature fruits in a 500 mg L^-1 GA₃ solution and seeds from mature fruits in a 1,000 mg L^-1 GA₃ solution have promoted a better germination and seedlings with greater vigor.

KEY-WORDS: Carica papaya; propagation; seedling vigor; growth regulator.