Seed biology of Hopea ponga (Dennst.) Mabb.(Dipterocarpaceae): An endemic and threatened tree species of the western ghats

Abstract

Seeds are a fundamental component of the plant life cycle, as they store the genetic information necessary for the next generation of plants to disperse, establish, develop and eventually reproduce to maintain the species. In tropical rainforests, there is still limited information on the physiology of seeds, phenology data, and ecological perspectives. Most tropical seeds have a short lifespan in soil and become non-viable. The genus Hopea is the largest genus in the Dipterocarpaceae family and is widely distributed throughout the Western Ghats, from lowland evergreen forests on the coastal plains to tropical evergreen forests. The physiological and biochemical studies provide strong evidence of the hard-to- process nature of the seeds of Hopea ponga. This is consistent with their quick growth after falling into damp conditions. The study has also demonstrated that the metabolism of active sugars, proteins, and lipids increased, along with lipid peroxidation, activities of free radical scavenging enzymes such as peroxidase (POD), polyphenol oxidase (PPO), and catalase (CAT), electrolyte leakage, phenolic accumulation, and more during the drying out of the seeds. These factors further affected the level of enzyme activities, lipid peroxidation, sugar metabolism, and more. Thus, the active metabolism and related changes during seed desiccation can be signals for identifying seed viability. The study suggests that the optimal seed storage conditions should be 20±2°C&40% RH in closed polycarbonate bottles for H. ponga. The metabolic imbalances that develop during various treatments can provide valuable information about the properties of different biomolecules and their functional behaviour. These imbalances can be considered markers for detecting viability and can help develop proper conservation measures through seed banking. The equilibrium of species in natural habitats has been destabilized due to human encroachment, endemic nature, over-exploitation, recalcitrancy, habitat specificity, irregular fruiting cycles, and other factors. This study could serve as a model for future research to better understand the seed physiology and biochemistry of other important species. Therefore, the study accomplishes the dual goals of conservation and sustainable utilization, particularly concerning the unique resources found in the Western Ghats