Spore germination inCylindrospermum sp.: Influence of gases and growth conditions

Influence of different gases on spore germination ofCylindrospermum sp. revealed that acetylene and ethylene suppressed the germination which was more pronounced at their higher concentrations. Germination was completely inhibited under the atmosphere of hydrogen and argon even when supplied with 1% CO₂. Carbon dioxide, both in air and in N₂, stimulated the process. However, higher concentrations of CO₂ inhibited the germination in a concentration-dependent manner, possibly due to a decrease in pH. Germination was completely arrested in the absence of light and nutrients. The energetic requirement for germination was not efficiently fulfilled by photosystem I (PS II was blocked by 3-(3,4-dichlorophenyl)-1,1-dimethylurea) or under conditions of anoxygenic photosynthesis (medium supplemented with sodium sulfide).