Details

Autor(en) / Beteiligte

• Uni, Daphna
• Klein, Tamir
• Masci, Tania
• Winters, Gidon
• Sheffer, Efrat

Titel

Strong regulation of nitrogen supply and demand in a key desert legume tree

Ist Teil von

• Environmental and experimental botany, 2024-08, Vol.224, p.105823, Article 105823

Ort / Verlag

Elsevier B.V

Erscheinungsjahr

2024

Link zum Volltext

Quelle

Access via ScienceDirect (Elsevier)

Beschreibungen/Notizen

• High abundance of legumes in drylands suggests that symbiotic nitrogen fixation provides an advantage in water-limited environments. However, the interactive effect of nitrogen availability and water scarcity on the nitrogen fixation strategies of dryland legumes remain largely unexplained. We conducted two experiments to test the effects of nitrogen availability and drought on symbiotic nitrogen fixation in two drought-adapted Acacia tree species. Seedlings were grown under deficient and sufficient levels of nitrogen and with and without an imposed drought to test the effect of resource availability on nitrogen fixation and plant growth. We found that seedlings that grew in extreme deficiency of nitrogen reached a similar biomass as seedling that grew with a sufficient supply of nitrogen, showing a high nitrogen-use efficiency. Nitrogen fixation was strongly downregulated (reduction of 90% in biomass allocation to nodules) when plants received sufficient nitrogen supply. Under nitrogen deficiency, drought had a slight negative effect on nodule biomass and total biomass. Under sufficient nitrogen, drought reduced nitrogen availability enough to induce an increase in symbiotic nitrogen fixation in the risk-averse A. raddiana but not in the risk-taking A. tortilis. We conclude that strong regulation of nitrogen fixation together with low nitrogen demand, and flexible strategies of carbon and nitrogen allocation, increase the chance of legume tree survival and establishment in dry and unpredictable environments. •The combination of water and nutrient limitation is globally common.•We analyzed growth and symbiotic nitrogen fixation in woody legumes under low water and nitrogen availabilities.•Strong downregulation strategy of N fixation was found when nitrogen was sufficient.•Low nitrogen demand allowed similar seedling growth with sufficient or deficient availability of nitrogen.•Regulation of nitrogen supply and demand sustained growth and survival under the combined stress of nitrogen and water.