Physiological responses of two common mosses to simulated nitrogen deposition in Jiuzhaigou

Abstract

In order to explore the effect of nitrogen deposition on physiological response of mosses in Jiuzhaigou, Sichuan Province, the local dominant mosses Actinothuidium hookeri and Hylocomium splendens were taken as the research objects, and NH4NO3 was used as the nitrogen source. Nitrogen deposition treatments were applied with control (0 kg N·hm-2·a-1), low (20 kg N·hm-2·a-1) and high (50 kg N·hm-2·a-1). The experiment lasted six months. The results were as follows: (1) The contents of reactive oxygen species, malondialdehyde, chlorophyll, proline and soluble protein were significantly increased by application of NH4NO3 solution. At the same time, the activities of its catalase, peroxidase, superoxide dismutase and ascorbate peroxidase were significantly increased when Actinothuidium hookeri was subjected to nitrogen deposition. (2) During the vigorous and late periods, the activities of its catalase, peroxidase and ascorbate peroxidase were significantly decreased when Hylocomium splendens was subjected to similar nitrogen deposition. (3) During the experiment, subordinate function value of Actinothuidium hookeri significantly increased with increase of NH4NO3 solution concentration. Response pattern of subordinate function value was different when Hylocomium splendens was subjected to different concentrations of NH4NO3 solution in the vigorous and late growth periods. In conclusion, physiological responses are different between two mosses subjected to nitrogen deposition. High concentration of nitrogen deposition can promote the growth of Actinothuidium hookeri. Hylocomium splendens can grow normally under the natural nitrogen deposition conditions and can withstand a certain degree of nitrogen deposition, but when the nitrogen deposition is too high, it will cause damage to it, the metabolism decreases and its growth is inhibited. Long-term nitrogen deposition may lead to future change of moss community composition in Jiuzhaigou, Sichuan Province.

Keywords

• nitrogen deposition
• actinothuidium hookeri
• hylocomium splendens
• physiological trait
• nh4no3