Pollen and Pollinator Limitation of Seed Initiation in Etlingera littoralis (J. K nig) Giseke (Zingiberaceae) in Klong Klai Basin, Khao Nan National Park, Thailand

Pollen and pollinator limitation of seed initiation in Etlingera littoralis (J. K nig) Giseke (Zingiberaceae) in Khlong Klai Basin, Khao Nan National Park, Nakhon Si Thammarat Province, was investigated using hand and open pollination in 3 stations (A, B and C). Stations A and B are located inside the National Park area, whereas station C is outside the National Park area. Stingless bees were the only pollinators observed at station C. The number of seeds initiated from the hand-pollinated flowers were compared to those of seeds initiated from open-pollinated flowers. The results showed that there was a pollen limitation in stations A (T = 2.802, Sig 2-tailed = 0.012) and B (T = 2.524, Sig 2-tailed = 0.021) on mean seeds/ovules (S/O) ratios. In station A, pollen limitation was slightly greater (mean difference = 0.547) than station B (mean difference = 0.501). In station C, pollen limitation was not significant (T = 0.410, Sig 2-tailed = 0.550) because there was small stingless bees, Trigona sp. that pollinated the flowers. However, a resource limitation in station C was found on mean ovules per flower (mean difference A,B = 9.893, mean difference A,C = 31.734 and mean difference B,C = 21.841).