Abstract
Respiration during the germination of Puccinia coronata uredospores was studied by floating the spores on liquid in Warburg flask of about 18ml volume. The respiratory rate (Qo2) on distiled water declines gradually during incubation at 25°C except when germination is very favourable due to a light load of spores (1.5mg spores per 2ml), in which a slight rise occurs temporarily in about 2 hours after spores were sown. The respiratory quotient (RQ) in the early and late stage of incubation is 0.48-0.66 and 1.04 respectively. The smaller the spore density and the better the germination, the higher is Qo2. This seems to be closely related to the self-inhibitors of spores. The addition of commercially available respiratory-substrates at the stationary growth-phase of germtubes has little effect on Qo2 except a slight stimulation by succinate. Almost all of well known enzyme-inhibitors used ratard Qo2, while a sight stimulation is seen in 2, 4-dinitrophenol alone. Self-inhibition of germination are overcome markedly by pelargonate and capronate, which are also able to stimulate Qo2.
