GERMINATION AND SURVIVAL OF <em>SHOREA</em> <em>TRAPEZIFOLIA</em>: EFFECTS OF DEWINGING, SEED MATURITY, AND DIFFERENT LIGHT AND SOIL MICROENVIRONMENTS

Abstract

Shorea trapezifolia, a rain forest dipterocarp endemic to Sri Lanka, shows potential as a plantation timber tree. Several experiments were carried out to determine the effect of seed maturity, removal of fruit wings, and varying light and soil conditions, on germination and survival of this species in the nursery. Results indicate that germination was immediate, occurring between four and ten days after the fruit fall. Seeds are recalcitrant and cannot be stored for periods greater than one to two weeks. The period of maximum seedling mortality between germination and establishment was found to be approximately the first 50 days. Partial shade is recommended for at least the first month after germination in the nursery to ensure maximum survival. The experiments showed significant genotypic differences in seed germination and seedling survival between cohorts of different parent-trees. This draws attention to the importance of selecting suitable maternal parent trees for nursery programmes. Seeds that fell later in a fruit fall were more viable compared to those that fell at the beginning, suggesting that seed collection for nursery propagation should be two weeks after initial fruit fall. Removing fruit wings had no effect on germination or survival and could be safely done for convenience of temporary storage and transport. The germination of seeds planted on forest top soil with litter was little affected by partial shade or exposure to full sun, but shade was more favourable for seedling survival. Germination and survival were poor on compact mineral soil and on compact mineral soil that had been scarified on the surface. Both treatments were exposed to full sun. This suggests the combination of partial shade and forest top soil with litter to be the best condition for nursery propagation. Some form of ground preparation and litter cover is needed for planting or to aid natural regeneration in disturbed sites, where mineral soil is exposed.