Alternative Materials for Plumule Initiation and Callus Induction of Coconut (Cocos nucifera L.) cv. Laguna Tall
Coconut (Cocos nucifera L.) is an important Philippine export crop. Coconut yields in the Philippines are low owing to high genetic variability and old, senile trees. To provide better quality replacement planting materials, somatic embryogenesis was introduced in the country. It produces uniform, disease-free planting materials, in a high volume at a shorter time than seedling propagation. However, this modern technology requires expert skill, costly equipment, and specialized laboratory-grade materials. Hence, low-cost material options must be considered. Using Laguna Tall coconut embryos, the plumule initiation study was laid out in a two-factorial completely randomized design with sugar (sucrose, white table sugar) and duration (1, 3, and 5 d) as factors. Likewise, the callus induction experiments had culture vessel (45, 60, and 100 mL) and sealing materials (polypropylene sheets with rubber band, aluminum foil with masking tape) as factors. Data were analyzed using ANOVA with LSD for mean separation. Plumule growth was initiated to remove the need for microscopy in plumule excision prior to callus induction. For plumule initiation, embryo plugs were held for 3 d in liquid medium with sucrose resulting in plumule protrusion. Highest percentage of healthy explants was produced in 45-mL glass jars. Moreover, white calli were most abundant in cultures sealed with aluminum foil and masking tape. The combination of 45-mL glass jar and aluminum foil with masking tape was the only treatment that produced white calli at the second culture cycle. Relative cost analysis further revealed that 45-mL glass jars sealed with aluminum foil and masking tape was cheapest at PhP 7.32 compared to 100-mL jars with polypropylene sheets and rubber band at PhP 22.68. Results suggest that the use of 45-mL glass jars with the combination of aluminum foil and masking tape can be cheaper alternatives to conventional materials for coconut plantlet production.