EFFECTS OF TEMPERATURE ON ACETYLENE-REDUCTION BY MATS OF BLUE-GREEN-ALGAE IN SUB-TROPICAL GRASSLAND

Temperature is the main factor governing the rate of acetylene reduction by mats of blue-green algae in sub-tropical kikuyu lawns. High midday temperatures (40.degree. C at soil surface) inhibit acetylene reduction and low temperatures prior to dawn reduce the rate of nocturnal acetylene reduction. Data obtained from laboratory studies on algal mats and on Nostoc isolated from the mats are in agreement with those from in situ measurements confirming an acetylene reduction of 30-35.degree. C with inhibition above 40.degree. C.