The importance of fruit set, fruit abortion, and pollination success in fruit production of teak (Tectona grandis)

Abstract

Teak ( Tectona grandis L.) is believed to have been introduced from India 400–500 years ago and there appear to be no old-growth natural forests. However, Indonesia has many teak plantation forests and 40%–50% of seeds for reforestation come from seed orchards and the remainder from plantations. In both, flower and fruit abortion results in low fruit set and thus seed production. We investigated flower and fruit development in a clonal seed orchard in East Java in 1999 and 2001 using cross- and open-pollinated trees. The rates of abortion using cross-pollinations showed a similar pattern but were lower than for open-pollinations. The highest rate of abortion in cross- and open-pollinations was during pollination and fertilization, ranging 11%–23% and 31%–32%/day, respectively, less during fruit initiation (5%–6% and 6%–8%/day) and the lowest was during fruit maturation (<0.5%/day). Cross-pollinations increased fruit production by 10-fold compared with open-pollinations. About 30% of flowers were pollinated with an average of five pollen grains per stigma in open-pollinations. Pollen viability varied among clones and time of day but was not affected by position of flowers in an inflorescence. We conclude that low pollination success and low pollen viability are major causes for low fruit production in teak and are related to insect pollinators.