Some Characteristics of Crassulacean Acid Metabolism in Five Nonsucculent Scrub Species Under Natural Semiarid Conditions
Summary Leaves of five nonsucculent scrub species, Carissa spinarum , Maba buxifolia , Gymnosporia emarginata , Flacourtia sepiaria and Dodonaea viscosa exhibited some features of Crassulacean acid metabolism (CAM) under natural semiarid conditions. The occurrence of some characteristics of CAM in these species was exemplified by the nocturnal stomatal conductance, dark carbon assimilation and high activity of phosphoenolpyruvate carboxylase, resulting in the greater degree of dark acidification. The detection of ribulose bisphosphate carboxylase activity and the low δ 13 C values ranged from -24.5 to -29.1 %0 suggested that these five species also utilize reductive pentose phosphate cycle of photosynthesis. The five species exhibiting some CAM characteristics are suggested to be grouped under flexible CAM species which fix carbon dioxide in the light or darkness under natural semiarid conditions. Further, these five species belonged to five diverse dicotyledonous families which hitherto are not known to possess any CAM characteristics.