Effects of elevated temperatures on germination and subsequent seedling vigour in recalcitrant Trichilia emetica seeds

An increase in atmospheric temperature, particularly in tropical regions, appears to be an inevitable consequence of global climate change. This is likely to affect plant diversity and performance, owing to the relationship between temperature and seed germination, and temperature and plant vigour. The aim of the present study was to investigate the potential effects of elevated temperatures on seed germination and subsequent seedling vigour in a recalcitrant-seeded (desiccation sensitive) tropical African forest species, Trichilia emetica. Freshly harvested T. emetica seeds were grown at ambient (24 +/- 2/14 +/- 2 degrees C) and elevated (29 +/- 2/20 +/- 2 degrees C) midday/night temperatures and monitored for germinability, respiratory activity, reactive oxygen species (superoxide and hydrogen peroxide) production, total antioxidant activity and ultrastructural integrity. Seedlings subsequently produced were subjected to various growth measurements to compare vigour between those grown at ambient and elevated temperatures. The results suggest that exposure to elevated temperatures (similar to 5 to 6 degrees C above ambient) did not disrupt metabolic and ultrastructural integrity in T. emetica embryonic axes and consequently did not compromise seed germination and subsequent seedling production. Provided that sufficient water is made available, elevated temperatures may even hasten germinative development in T. emetica seeds and improve the competitive ability of seedlings subsequently produced by enhancing seedling growth rates, leaf area and biomass allocation to aerial parts of the plant. (C) 2013 SAAB. Published by Elsevier B.V. All rights reserved.