Effect of chemicals on disintegration of the operculum in oil palm (Elaeis guineensis) seeds for early germination

摘要

Seed dormancy (mechanical) is a persistent problem in oil palm and it takes six months to one year for germination to occur under natural conditions. With existing seed processing methods, germination takes nearly 110 days involving disintegration of the mesocarp and operculum (mechanical barrier for dormancy), pretreatment and germination. In this study, we attempted to improve germination by using chemicals to promote disintegration of the operculum and breaking of dormancy. In addition to distilled water as control, CaCl2, MgSO4, KNO3, KH2PO4, K2SO4, NaOH, DMSO and H2O2 at different concentrations were tested. GA(3) and thiourea combined with NaOH, DMSO and H202 at different concentrations were also used to treat the fresh fruits. MgSO4, KNO3, KH2PO4 and K2SO4 were not effective in the disintegration of the operculum, hence no improvement in germination was observed. However, 0.25-0.75 M NaOH and combinations of 0.25-0.75 M NaOH with 0.13-0.39 M thiourea did result in complete disintegration of the mesocarp and operculum while maintaining the viability of the embryo up to 10 days, as evident from a tetrazolium test and high germination (55-72%). Whereas, water could disintegrate the mesocarp within 10 days, did not affect embryo viability and resulted in 90% germination, there was no effect on the operculum.