Ecology of seed germination in threatened trees: a review

Abstract

The future of many tree species is at risk due to the rapid decline of the world’s forests, over-exploitation for timber, seeds, oils, resins, fruits and bark. In addition, seed germination in many threatened species is convoluted due to various physical factors such as moisture, light and the presence of thick seed coat as well as physiological factors such as seed dormancy. Studies pertaining to seed germination, storage behaviour, dormancy-breaking techniques, particularly of threatened tree species at global level are limited. Therefore, the present study was conducted to assess the progress made in the field of seed germination as well as the challenges that exist in the regeneration of such species that are of conservation value. The results obtained from the analysis of 78 threatened tree species showed that moisture is a critical factor for recalcitrant seeds, while species with orthodox seeds require a pre-treatment for breaking dormancy. Although most of the studies on dormancy-breaking techniques have demonstrated the effectiveness of one or two methods on seed germination, a combination of treatments as well as use of plant growth regulators improved the ability of seeds to germinate. Water, light, nutrients and a favourable substratum are major regulatory factors that affect germination, growth and establishment of tree species. The findings emphasize the need to develop guidelines for proper seed handling and understand germination protocols necessary for ecosystem management that would aid both in maintaining biodiversity values and conservation of threatened species.

Keywords

Disturbance / Dormancy / Growth regulators / Scarification / Treatments

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Funding

University Grants Commission(RGNF-JRF (F1-17.1/2013-14/RGNF-2013-14-ST-NAG-43868/ (SA-III/Website). Dated: 06-Feb-2014))