Effect of gibberellic acid and thiourea on seed germination, growth and survival of papaya (Carica papaya L.) cv. Pusa nanha and Pusa delicious

Papaya (Carica papaya L.) is mainly propagated through seeds and seedlings are raised in the nurseries before transplanting in to main field. The seeds are covered with sarcotesta, a whitish succulent and translucent material, which has been reported to delay germination. The freshly extracted seeds exhibit dormancy, when sown immediately and the dormancy can be broken by after-ripening by storage for a short period, but prolonged storage also results in poor germ inability. Treatment of seeds with growth regulators and certain chemicals has been found to break dormancy and improve the germination. A field experiment was carried out at Department of Horticulture, Sam Higginbottom Institute of Agriculture, Technology and Science, Allahabad. India during 2012-13. The experiment was laid out in randomized block design with 13 treatments in three replications on different cultivars. The treatments included soaking the seed in GA3 (100, 200 and 300 ppm), and Thiourea (1000, 2000, and 3000) for 12 hr duration along with a control. The results revealed that maximum germination (86.66%), seedling height (26.13cm), number of leaves (14.83), stem diameter (10.36 mm), plant speared (24.25cm2), survival percentage (84.61%) and minimum days required for completion of germination (15.33) were recorded in GA3 at 200 ppm in cv. Pusa nanha, followed by seed treatment with GA3 300 ppm in cv. Pusa nanha. The least values were recorded in the control.