CRASSULACEAN ACID METABOLISM CRITERIA SHOWN BY 3 SPECIES FROM FLORA OF QATAR

Potentiality of Crassulacean acid metabolism (CAM) was studied in thre e succulent species of the flora of Qatar. Some CAM criteria, namely d iurnal oscillation of titratable acidity, malic acid content and succu lence, were assessed in Anabasis setifera, Salsola baryosma and Zygoph yllum qatarense, growing in their natural habitat. All species showed a pattern of diurnal fluctuation of acidity and malic acid content typ ical of CAM plants. Succulence in three species fluctuated very weakly along the diurnal cycle. Only in Salsola and Zygophyllum did irrigati on damp the diurnal oscillation in acidity and malic acid. In irrigate d plants of the three species, values of acidity and malic acid conten t were generally less than those in nonirrigated plants (except noctur nal values of acidity and malic acid in Anabasis). Succulence values, on the other hand, were higher under irrigation. Hence A. setifera is a constitutive CAM plant and S. baryosma and Z. qatarense are inducibl e CAM plants.