Abstract: Mosses are important surface cover in the woodlands and play important ecological functions. Water availability is the most important factor affecting the growth of mosses. Changes of water content may cause the physiological response of mosses. We examined the oxidative damage, plant defense, antioxidant capacity and photosynthetic recovery ability of three moss species (Entodon concinnus, Entodon caliginosus and Barchythecium albicans) that are widely distributed in the woodland in the hilly loess region of China under different drying rates, to reveal their physiological desiccation tolerance. The results showed that: (1) All the three moss species were subjected to drought stress after drying, and the contents of malondialdehyde (MDA), soluble protein, soluble sugar, and the activities of peroxidase (POD) and superoxide dismutase (SOD) of the three mosses increased after drying. (2) The degrees of drought stress suffered by the three species varied with the drying rate, but were intensified by rapid drying. The contents of MDA, soluble protein, soluble sugar, and the activities of POD and SOD of the three species were higher after rapid drying than that after slow drying. (3) The drought stress caused by drying rate of the mosses was different among species. After drying, the increase degrees of the MDA, soluble protein, soluble sugar contents, and POD and SOD activities of the three species were different. (4) B. albicans showed a higher desiccation tolerance than the other two species, and the oxidative damage of B. albicans was the lowest after drying. The MDA content of B. albicans was significantly lower by 37.7% than that of E. caliginosus after rapid drying, and 39.3% lower than that of E. concinnus after slow drying. The cell regulation ability of B. albicans was higher than that of E. caliginosus and E. concinnus. The soluble sugar content of B. albicans was 57.3% and 50.9% higher than that of E. concinnus and E. caliginosus after rapid drying, respectively, and 13.6% and 99.8% higher after slow drying. B. albicans showed a strong antioxidant capacity. Compared with E. concinnus and E. caliginosus, POD activity of B. albicans after rapid drying was increased by 120% and 260%, respectively, and increased by 19.4% and 240.0% after slow drying, respectively. B. albicans showed a strong photosynthetic recovery ability. The recovery rate of chlorophyll content was 64.4% after rapid drying-rehydration, which was 55.7% and 13.1% higher than that of E. concinnus and E. caliginosus, respectively. Drying process increased drought stress of the mosses, which was intensified with increases of the drying rate. Different moss species showed different tolerance to desiccation, and the moss species with higher desiccation tolerance showed stronger resistance to water stress during the drying process. Our results would provide a scientific basis for the study of the ecological function and the protection of diversity of mosses.

Key words: understory moss, drying rate, drying-rehydration, antioxidant character, osmoregulation capability