Influence of light intensity on the responses of seedlings of neotropical tree species to nitrogen source

• Published in: Environmental and experimental botany Vol. 228; p. 106007
• Main Authors: Debiasi, Tatiane V., Calzavara, Anderson K., Gomes, Diego G., Andreas, Izabelle R., Rondina, Artur B.L., Duarte, Karoline E., Pereira, Rodrigo M., Batista, Bruno L., Pimenta, José A., Seabra, Amedea B., Centeno, Danilo C., Gaspar, Marília, Oliveira, Halley C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2024
• Subjects: Ammonium; biomass; botany; canopy; Cariniana estrellensis; Cecropia; energy; growth retardation; Guarea; hydroponics; leaf area; light intensity; Metabolic profiling; Neotropics; Nitrate; nitrates; nitrogen; Nitrogen metabolism; nutrient content; Oxidative stress; Photosynthesis; seedlings; shade tolerance; Shade-tolerant; species; trees; understory; Metabolic profiling; Oxidative stress; Ammonium; Nitrate; Nitrogen metabolism; Photosynthesis; Shade-tolerant
• ISSN: 0098-8472
• DOI: 10.1016/j.envexpbot.2024.106007

Light intensity plays a crucial role in N uptake and assimilation in plants, but its interaction with different N sources is overlooked. Considering the high energy required for N assimilation, it is hypothesised that low light is critical for the seedling development with both N sources, but with increased light intensity, growing with nitrate (NO3-) becomes favourable in relation to ammonium (NH4+). Seedlings of Cecropia pachystachya (pioneer), Guarea kunthiana (shade-tolerant, understory) and Cariniana estrellensis (shade-tolerant, canopy) were grown in hydroponic medium with NO3- or NH4+ as the sole N source and subjected to low (LL) or high light (HL) for 60 days. All three species showed a decrease in growth when cultivated with NH4+, compared to NO3-, under HL, but not under LL. The decrease in biomass reached 54 % in C. pachystachya, 36 % in G. kunthiana and 26 % in C. estrellensis. Growth reduction was associated with stomatal limitation of photosynthesis and reduced leaf area in C. pachystachya, and with non-stomatal limitation of photosynthesis and oxidative stress in G. kunthiana. Cation uptake was negatively affected by NH4+ in all species. Cariniana estrellensis showed no photosynthetic limitation and showed a higher tolerance to NH4+ under HL in terms of nutrient content. In conclusion, neither N source significantly favors seedling development under LL, while NH4+ is considerably more unfavorable for seedling development than NO3- under HL. •Regardless of the N source, low light limited seedling growth in all three species.•Under high light, NH4+ was considerably unfavorable for seedling development.•Photosynthesis was impaired by NH4+ in two species under high light.•Carbon drain for NH4+ assimilation was a symptom of NH4+ toxicity under high light.•Cation uptake was negatively affected by NH4+ in all species.