Effects of dry heat on seed germination in selected indigenous and alien legume species in South Africa

The effect of dry heat on the percentage germination, germination rate and lethal temperatures of selected legume species was investigated by exposing seeds to different intensities and durations of heat. Two alien invasive legumes (Acacia saligna and A. cyclops) and two indigenous legume species: Podalyria calyptrata, which is a fynbos species, and Virgilia oroboides, a forest precursor, were tested. Results were compared to predictions based on published accounts of the species’ ecology. Acacia saligna and P. calyptrata fitted predictions: high percentage germination, fast germination rates and a tolerance to high temperatures; with A. saligna outperforming P. calyptrata in the latter two responses. Both A. cyclops and V. oroboides did not conform to predictions: dry heat had little positive effect on germination, and in A. cyclops it had a negative effect. Die effek van droë hitte op die ontkiemingspersentasie en ontkiemingstempo sowel as die effek van dodelike temperature op geselekteerde peulplantspesies is ondersoek deur die temperature sowel as die blootstellingstyd te varieer. Twee uitheemse indringerpeulplante (Acacia saligna en A. cyclops) en twee inheemse peulplantspesies: Podalyria calyptrata, wat ’n fynbosspesie is en Virgilia oroboides, ’n woudpionier, is ondersoek. Die resultate is vergelyk met voorspellings wat gebaseer is op gepubliseerde verslae van die spesies se ekologie. Acacia saligna en Podalyria calyptrata stem ooreen met die voorspellings wat gemaak is: hoë ontkiemingspersentasie, hoë ontkiemingstempo en ’n toleransie vir hoë temperature; Acacia saligna oortref Podalyria calyptrata wat laasgenoemde twee aspekte betref. Acacia cyclops sowel as Virgilia oroboides wyk af van voorspellings wat gemaak is: droë hitte het ’n klein positiewe effek op ontkieming en by Acacia cyclops was die effek negatief.