Cryopreservation of ‛Laguna Tall’ Coconut (Cocos nucifera Linn.) Mature Zygotic Embryos
J. Kumaunang, O. P. Damasco and C. M. Protacio
‘Laguna Tall’ coconut (Cocos nucifera L.) zygotic embryos were successfully cryopreserved through cryoprotection using pretreatment-desiccation or vitrification, rapid freezing in liquid nitrogen, rapid thawing at 40°C for 2 min, and recovery and growth of frozen embryos in coconut germination medium. Pretreatment in 0.5 M sucrose for 1 d followed by 24 h desiccation in silica gel gave the highest recovery and complete germination (47%) of cryopreserved embryos. This was followed by 24 h desiccation alone (43%), 3 d sucrose pretreatment + 24 h desiccation (33%), and the least recovery from vitrification using PVS4 solution (13%). Embryo reinvigoration as a post thawing treatment and addition of 0.5 mg L-1 benzyl amino purine + 1.0 mg L-1 naphthalene acetic acid onto Y3 germination medium hastened recovery and significantly improved complete germination of cryopreserved embryos. The study demonstrated the feasibility of cryopreservation for long-term conservation of coconut genetic resources and for the first time reported on the success in cryopreservation of ‛Laguna Tall’, an endemic coconut variety grown in the Philippines.