Sahar Mirzaei - Ph.D. of Horticulture and post doctorate Researcher in Department of Horticulture Science, College of Agriculture, Shiraz University, Shiraz, Iran.
Morteza Khoshkhui - Professor, Department of Horticulture Science, College of Agriculture, Shiraz University, Shiraz, Iran.

Drought is the most important abiotic factor that limits at least 25% of production of world fields. The quantity and quality of plant growth depend on cell division, enlargement and differentiation and all of these factors may be affected by water stress. Also, different plant compounds are strongly influenced by different environmental conditions. The present study was carried out in Eram Botanical Garden Research Centre to investigate the degree of tolerance of four genera of succulents (Crassula portulacaria, Echeveria elegans, Kalenkoe laxiflora, Echeveria affinis) by measuring morphological and physiological characters under water deficit conditions. Uniform plants were planted (in 20 cm pots) and kept at open area where they would be finally planted in landscape. Six irrigation intervals (5, 10, 15, 20, 25 and 30 days) were applied until the plant soils reached to field capacity for about 2 critical warmest months of June and July in the area. The experiment was conducted as a completerandomized block design with four replications for each treatment. Data were analyzed with SPSS 12.0 software and the mean values were compared using Tuckey's test at 5% level of probability. Results showed that water deficit stress decreased shoot and root fresh and dry weights. Proline content, electrical conductivity and total chlorophyll content was significantly increased in four genera of succulents under the study under the conditions of this experiment. Considering all the characteristics measured, a 5 –day irrigation interval was resulted in highest growth in all genera studied.

water stress, drought, succulents, chlorophyll, proline