Pollination biology of Coffea liberica W. Bull ex Hiern var. liberica in Lipa, Batangas, Philippines

The floral biology and pollination of Coffea liberica var. liberica in an agroecosystem at Lipa, Batangas, Philippines was studied. The inflorescences are non-terminal and blooming is asynchoronous. The flowers are herkogamous and highly variable. They are short-lived (2 days) and the anthers fully represented only on the first day. Anthesis is from 0500-1200 h peaking at 0800 h. The maximum attraction distance of the flowers is at 87.70 +- 11.05 cm. Nectar volume averaged at 9.27 +-3.90 uL while its calorie content based on the energy contributed by sucrose is 1.91 +- 0.80 cal/uL. The nectar contained high amount of sugars, phenols, flavonoids, anthocyanidins and saponins. Alkaloids were absent while anti-oxidant activity is present. The pollen grains were simple and numerous with high viability of 91.16 +- 4.11%. The germination rate of pollen grains using differential sucrose solutions is low at 64.65 +- 9.53%. Majority of the pollen had moderate amounts of starch (62.23%) and lipids (70.61%). Only three pollinator visits were needed for effective pollen deposition. Pollination was through entomophily with pollen and nectar as rewards. Floral visitors were 22 insect species belonging to 15 families and 5 genera. Apis mellifera, Apis cerana and Trigona biroi were the most frequent visitors but only A. mellifera and A. cerana were considered as the true pollinators. Pollen viability and germination, stigmatic receptivity, nectar production and floral visitation were all found to be significantly highest at 0800 h. Floral characters and indices, such as pollen-ovule ratio, outcrossing index, index of self-incompatibility and selfing rate, indicate that the plant is obligately xenogamous and highly self-incompatible, thus requiring outcrossing.