Effect of Liquid Nitrogen Storage Time on the Survival and Regeneration of Somatic Embryos of Cocoa

Investigations were undertaken on the effect of liquid nitrogen (LN) storage time on survival and regeneration of somatic embryos of cocoa (Theobroma cacao l.). Somatic embryos from different cocoa genotypes (AMAZ 32, AMAZ 10-1, AMAZ 12, SIAL 93, and IMC 14) at 15.45% moisture content were cryopreserved in LN for one h, four and eight weeks. Somatic embryos of the genotypes emerged from the alginate beads at different periods 4 to 12 weeks post-cryopreservation. Individual genotypes subjected to low temperature storage time did not show significant differences in post-cryopreservation survival, although different genotypes responded differently with AMAZ 12 and IMC 14 recording the highest and lowest mean survival rates of 58% and 35%, respectively. Plantlets originating from five genotypes had been weaned and developed normally comparable to non-cryopreserved somatic embryo-derived plantlets in the glasshouse. The effects of low temperature storage time on survival and genetic stability of somatic embryos using genotypes from the same parental and distinct lines may contribute to long-term storage of cocoa germplasm.