Role of pollen production in mating success in some tropical tree species

This study was conducted to estimate the amount of pollen produced by three entomophilous and two ornithophilous tropical woody taxa. It seeks to establish their reproductive success in relation to each other and contribution to the concentration of pollen in the air. The taxa selected were Bombax ceiba, Erythrina stricta (both ornithophilous), Lagerstroemia speciosa, Mesua ferrea and Schima wallichii (all entomophilous); which were studied in three different calendar years (2010, 2011 and 2012). M. ferrea produced the highest number of pollen grains per tree (3.85–6.60 × 1010) and B. ceiba highest number of pollen grains per anther (18,610 ± 1,189.49). The pollen grains produced were estimated to be about 100 million per tree in all the studied species except M. ferrea, which produced about 10 billion pollen grains per tree. There were both good and poor production years in all the studied species. During the course of the 3-year study, B. ceiba, E. stricta and S. wallichii produced maximum number of pollen grains per tree in the year 2011, whereas maximum pollen production was observed in M. ferrea in the year 2010. However, the 2 years (2010 and 2012) mass production was observed in L. speciosa. During the high pollen production years, the fruit setting was also recorded to be high. It is interesting to point out that in E. stricta, the fruit setting was 88.5 and 91.72 % higher (i.e. 39.12 ± 3.63 %) in the year 2011 as compared to the years 2010 (4.48 ± 0.63 %) and 2012 (3.24 ± 0.49 %), respectively.