REPRODUCTIVE STUDIES AND FRUIT SETTING OF TEAK (TECTONA GRANDIS LINN.F.) POLLINATED BY MAJOR POLLINATORS IN THE SEED ORCHARD

Abstract

A study of some aspects of the reproductive biology of teak was conducted at 6x6 m and 12x12 m plot of Maegar seed orchard, Phayao province during April 2002-September 2003. The rate of fruit abortion and reproductive success of teak trees growing at the two spacings are not statistically different. However in terms of viable seeds and seed/ovule ratio, it is likely that the fruits from trues in the 6x6 m are of higher quality than in the 12x12 m. At 6x6 spacing, the average of seed to ovule ratio (0.134 ±0.003) is significantly higher than 12x12 m (0.118 ±0.003). Investigation of the initial front set (7 days after pollination) from opened pollination during 0900-1300 h by major insect pollinators found that the large-sized insects (Nomia sp. and Vespa affinis) which commonly fly between inflorescences or trees contribute to higher fruit set (38.52%, 37.84% respectively). The group of smaller insects, wild bees, which mostly fly shorter distances or fly within the same inflorescence or tree lead to lower fruit set; the percentage of fruit set obtained from: Trigona collina, T. laeviceps, T. terminata, Lasioglossum sp., Ceratina spp., and Apis florea were 29.41, 27.59, 23.64, 23.53, 23.08. and 22.64, respectively.