Abstract:The pot experiment was conducted to study the changes of plant growth and physiological characteristics of 1- and 3-year-old Calligonum caput-medusae under different irrigation treatments (30%, 40%, 50%, 60%, and 85% field water capacity(FC)), and find out the suitable water condition for the plant growth. The plant height, canopy, base diameter, assimilating branch diameter, and the biomass of whole plant declined significantly with the decreasing of irrigation amount for both 1- and 3-year-old plants. At both growth stages, stem was the main organ for dry matter accumulation. The dry matter allocation proportion of stem was positively affected by the increasing irrigation amount, but that was negatively for root. However, C.caput-medusae of 3-year-old could not produce fruit at the lowest irrigation level, and the fruit yield was significantly lower at 85% FC than that by other treatments. The assimilating branches had high chlorophyll and MDA contents under lower irrigation treatment. The damage of plasmamembrane was serious under drought condition. However, there was a large number of proline accumulated in the assimilating branches to adapt to water stress. The damage of plasmamembrane was reduced with the increasing of irrigation, and the proline and soluble sugar accumulations were complemented each other. The chlorophyll content decreased significantly under the highest irrigation treatment for both 1- and 3-year-old C.caput-medusae. Based on all of the above determined indexes, the comprehensive adaptability was in the following order: 60% FC>85% FC>50% FC>40% FC>30% FC. Therefore,the medium irrigation level (60% FC) is appropriate for establishing C.caput-medusae seedlings in this area.