A simple protocol for cryopreservation of zygotic embryos of ten accessions of coconut (Cocos nucifera L.)

A simple and efficient cryopreservation protocol for coconut zygotic embryos has been developed. Embryos were inoculated in Petri dishes on medium containing 3.2 M glucose, which were placed in hermetically closed containers containing 80 or 160 g silica gel for 48 or 24 h. Moisture content of embryos at the end of this treatment varied between 0.25 and 0.65 g g(-1) DW, depending on the accession. Embryos were then transferred for cryopreservation by rapid immersion of cryotubes in liquid nitrogen. After rapid re-warming, embryos were transferred to culture medium containing Eeuwens mineral elements for germination. This protocol was applied to ten accessions representative of coconut genetic diversity, with germination percentages of cryopreserved embryos between 13.7% and 74.7%.