Abstract
Dark CO2 fixation and phosphoenolpyruvate-carboxylase activity were studied in fluoride-necrotic and control soybean leaves. Necrotic leaves had a higher rate of dark CO2 fixation than control leaves both in vivo and in vitro (phosphoenolpyruvate carboxylase). Results suggested that the accumulation of organic acids and amino acids in necrotic leaves resulted from an increased rate of dark CO2 fixation. The possible role of fluoride in stimulating the car-boxylation and its implication to necrosis are discussed.