九寨沟两种常见藓类植物对模拟氮沉降的生理响应

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

关键词:  氮沉降, 锦丝藓, 塔藓, 生理特征, 硝酸铵

Key words:  nitrogen deposition, Actinothuidium hookeri, Hylocomium splendens, physiological trait, NH₄NO₃

摘要:

为探讨氮沉降对九寨沟藓类植物的影响,该研究以当地优势藓类植物锦丝藓(Actinothuidium hookeri)和塔藓(Hylocomium splendens)为对象,以NH₄NO₃为氮源,设置对照(0 kg N·hm^-2·a^-1)、低浓度(20 kg N·hm^-2·a^-1)、高浓度(50 kg N·hm^-2·a^-1)3种处理,开展为期6个月的氮沉降模拟实验。结果表明:(1)氮沉降处理导致两种藓类植物的活性氧、丙二醛、叶绿素、脯氨酸和可溶性蛋白含量显著增加,同时锦丝藓过氧化氢酶、过氧化物酶、超氧化物歧化酶、抗坏血酸过氧化物酶活性增加。(2)对于生长旺期和生长末期的塔藓,氮沉降导致其过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶活性降低。(3)锦丝藓的综合隶属函数值随氮沉降浓度增大而增加,在生长旺期和生长末期,塔藓综合隶属函数值对氮沉降的响应存在差异。综上认为,两种藓类植物对氮沉降处理的生理响应存在差异,高浓度氮沉降能促进锦丝藓生长,塔藓在自然氮沉降条件下能正常生长且能承受一定程度的氮沉降,但当氮沉降过高时则会对其造成伤害,新陈代谢下降,生长受到抑制,长时期的氮沉降可能导致未来九寨沟藓类植物群落发生改变。

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.