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Morphological and physiological responses to contrasting nitrogen regimes in Populus cathayana is linked to resources allocation and carbon/nitrogen partition

Luo, Jie, Zhou, Jing-Jing, Masclaux-Daubresse, Céline, Wang, Nian, Wang, Hui, Zheng, Bo
Environmental and experimental botany 2019 v.162 pp. 247-255
Populus cathayana, abscisic acid, ammonium, ammonium nitrate, biomass, carbon, ecosystem services, fertilizer application, glutamate dehydrogenase, growth performance, jasmonic acid, leaves, nitrate reductase, nitrogen, nitrogen fertilizers, nutrient use efficiency, nutrients, photosynthesis, physiological response, plantations, resource allocation, roots, salicylic acid, saplings, tissues
Nitrogen (N) is essential for fast growth in Populus species. For successful forestation, it is necessary to estimate growth performance and N utilization efficiency under different N regimes. Saplings of P. cathayana were subjected to 0.25 (N deficiency), 2.5 (N normal), or 7.5 (N fertilization) mM NH4NO3 for six weeks, respectively. The morphological and physiological parameters relative to N responses were measured. In comparison with normal N, N deficiency stimulated root biomass, a reduced biomass of leaves and stem, and an elevated root to shoot biomass ratio; in contrast, the biomass of all tissues was unaltered under N fertilization. Concentrations of NH4+ in roots and leaves, and of NO3− in roots were decreased in response to N deficiency, corresponding to lower activities of glutamate dehydrogenase (GDH) and nitrate reductase (NR) in both roots and leaves, and of glutamate synthase (GOGAT) in the roots of P. cathayana exposed to N deficiency, whereas the opposite effect was observed in most cases under N fertilization. The imbalance of nutrients, accumulation of large amounts of stress hormones (ABA, JA, and SA), and reduced photosynthesis were observed in the plants treated with N fertilization. P. cathayana displays morphological and physiological plasticity to changes in N levels, and the growth driven by N appears closely related to the internal resource allocation and carbon/nitrogen partition. Our data indicate that moderately reducing the dose of N fertilizer may have both economic and environmental benefits in commercial poplar plantations.