Effects of Warming and N Deposition on the Physiological Performances of Leymus secalinus in Alpine Meadow of Qinghai-Tibetan Plateau
Hao Shen, Shikui Dong, Shuai Li, Wenying Wang, Jiannan Xiao, Mingyue Yang, Jing Zhang, Xiaoxia Gao, Yudan Xu, Yangliu Zhi, Shiliang Liu, Quanming Dong, Huakun Zhou, Jane C. Yeomans
Abstract
Warming and Nitrogen (N) deposition are key global changes which may affect eco-physiological process of territorial plants. In this paper, we examined the effects of warming, N deposition and their combination on the physiological performances of Leymus secalinus. Four treatments were established in an alpine meadow of Qinghai-Tibetan plateau: control (CK), warming (W), N deposition (N) and warming plus N deposition (NW). Warming significantly decreased the photosynthetic rate (Anet), stomatal conductance (gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr), while N deposition and warming plus N deposition significantly increased those parameters of Leymus secalinus. Warming significantly increased the VPD and Ls, while N deposition and warming plus N deposition had a significant positive effect. Warming negatively reduced the leaf N content, Chla, Chlb, and total Chl content, while N deposition significantly promoted these traits. Warming, N deposition and their combination significantly increased the activity of SOD, POD and CAT. Besides, warming and warming plus N deposition significantly increased the MDA content, while N deposition significantly decreased the MDA content. N deposition and warming plus N deposition significantly increased the Rubisco activity while warming showed no significant effect on Rubisco activity. N deposition and warming plus N deposition significantly increased the Fv/Fm, ΦPSII, qP, and decreased NPQ, while warming significantly decreased the Fv/Fm, ΦPSII, qP, and increased NPQ. N deposition strengthened the relations between gs, Chl, Chla, Chlb, Rubisco activity and Anet. Under warming, only gs showed a significantly positive relation with Anet. Our findings suggested that warming could impair the photosynthetic potential of Leymus secalinus enhanced by N deposition. Additionally, the combination of warming and N deposition still tend to lead positive effects on Leymus secalinus in short term.