Responses to simulated nitrogen deposition by the neotropical epiphytic orchid Laelia speciosa

PeerJ

Erick de la Barrera¹  Roberto Lindig-Cisneros¹  Edison A. Díaz-Álvarez² 

[1]Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, Michoacán, Mexico

[2]Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, Distrito Federal, Mexico

关键词: Acid rain;    Biodiversity loss;    CAM;    Conservation physiology;    δ15N;    Nitrogen pollution;   

DOI  :  10.7717/peerj.1021

来源: DOAJ

【 摘 要 】

Potential ecophysiological responses to nitrogen deposition, which is considered to be one of the leading causes for global biodiversity loss, were studied for the endangered endemic Mexican epiphytic orchid, Laelia speciosa, via a shadehouse dose-response experiment (doses were 2.5, 5, 10, 20, 40, and 80 kg N ha−1 yr−1) in order to assess the potential risk facing this orchid given impending scenarios of nitrogen deposition. Lower doses of nitrogen of up to 20 kg N ha yr−1, the dose that led to optimal plant performance, acted as fertilizer. For instance, the production of leaves and pseudobulbs were respectively 35% and 36% greater for plants receiving 20 kg N ha yr−1 than under any other dose. Also, the chlorophyll content and quantum yield peaked at 0.66 ± 0.03 g m−2 and 0.85 ± 0.01, respectively, for plants growing under the optimum dose. In contrast, toxic effects were observed at the higher doses of 40 and 80 kg N ha yr−1. The δ13C for leaves averaged −14.7 ± 0.2‰ regardless of the nitrogen dose. In turn, δ15N decreased as the nitrogen dose increased from 0.9 ± 0.1‰ under 2.5 kg N ha−1yr−1 to −3.1 ± 0.2‰ under 80 kg N ha−1yr−1, indicating that orchids preferentially assimilate NH4+ rather than NO3− of the solution under higher doses of nitrogen. Laelia speciosa showed a clear response to inputs of nitrogen, thus, increasing rates of atmospheric nitrogen deposition can pose an important threat for this species.

【 授权许可】

Unknown