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- Cryopreservation of 'Laguna Tall' Coconut (Cocos nucifera L.) Embryos.
Cryopreservation of 'Laguna Tall' Coconut (Cocos nucifera L.) Embryos.
Thesis Abstract:
‘Laguna Tall’ coconut (Cocos nucifera L.) embryos were successfully cryopreserved by two cryogenic procedures with complete germination of up to 46.67 percent after immersion in liquid nitrogen. Two methods, namely: pretreatmentdesiccation and vitrification were effective for cryopreservation of coconut, while embryos pregrowth in sucrose as a cryoprotectant did not work at all. The pretreatmentdesiccation method gave the highest percentage of germination (33.34-46.67%) as compared with vitrification method, which had only 13.33 percent. Reinvigoration of the embryos and addition of plant growth regulators to the medium can hasten recovery and improve percent germination of coconut embryos after immersion in liquid nitrogen.
To avoid lethal intracellular ice formation, the moisture content of the embryos had to be reduced. Results demonstrated that coconut embryos could be desiccated down to moisture content of 10.15 percent without appreciable loss in viability (70%) and still retain their germinability (50%). Desiccation was accomplished by placing the embryos in airtight jars containing 100g silica gel for 24 hours. Embryos desiccated under the laminar airflow hood did not fare as well. Desiccation to moisture content below 8 percent was found to be the critical moisture content for ‘Laguna Tall’ embryos.
Sucrose, to be effective as a cryoprotectant, must be used in combination with desiccation. Sucrose at a concentration of 0.5 M when combined with desiccation for 24 hours in 100g silica gel was beneficial as a pretreatment or cryoprotectant giving high percentage viability (86.67%) and germinability (53.69%) with less membrane leakage. Higher concentrations of sucrose were deleterious.
The feasibility of long-term conservation for tall coconut genetic resources had been confirmed. Further study is necessary to confirm the applicability of these protocols to a wider array of genotypes to complement gene bank.
