Improving Papaya Seedling Emergence by Matriconditioning and Gibberellin Treatment

Papaya (Carica papaya L.) seeds germinated poorly at 25C in the presence of gibberellin (GA4+7) or following matriconditioning at 25C for 4 days. However, a combined treatment of matriconditioning and GA 4+7 for 4 days synergistically promoted germina- tion and seedling emergence. Drying the seeds after conditioning reduced the percentage of seedling emergence in the combined treatment involving 400 µ M GA4+7 only. Combining matriconditioning with 100 or 200 µM GA4+7could effectively reduce germination time and improve seedling emergence and is recommended as a standard procedure for testing papaya seed germination. Papaya is cultivated in many tropical and subtropical regions. Papaya is propagated com- mercially by seed. The seed is enclosed in a gelatinous sarcotesta (aril or outer seedcoat), which is formed from the outer integument. Papaya seed germination frequently is slow, erratic, and incomplete (Chacko and Singh, 1966; Lange, 1961; Ramirez, 1961; Yahiro, 1979). While the sarcotesta can delay germi- nation, dormancy also is observed in seeds from which the aril has been removed (Lange, 1961; Yahiro, 1979; Yahiro and Oryoji, 1980).