Saline-alkaline conditions altered Bolboschoenus planiculmis carbon and nitrogen allocation tradeoffs

Soil salinization is an important factor that limits global agricultural production, specifically limiting the effectiveness of nitrogen-carbon resources and inhibiting plant growth. However, previous observations have focused on resource allocation, and there is little information about the coordination of carbon-nitrogen acquisition, allocation, and regulatory processes. We performed glasshouse pot experiments under different saline-alkaline conditions, and we measured 66 above- and belowground functional traits of Bolboschoenus planiculmis, to examine carbon-nitrogen resource acquisition and allocation strategies and their driving processes. Saline-alkaline conditions shifted B. planiculmis root-leaf functional traits toward a more acquisitive phenotype. Under low saline-alkaline conditions, although the root-leaf economic strategy inhibited resource acquisition efficiency, the opportunistic carbon-nitrogen capture and allocation strategy contributed to the maintenance of normal growth. However, highly saline-alkaline conditions led to the early enrichment of carbon-nitrogen resources in the corm. Additionally, saline-alkaline conditions altered the importance of physiological and biochemical processes in the carbon and nitrogen allocation regulatory network. In summary, B. planiculmis uses an opportunistic resource acquisition strategy under saline-alkaline conditions and a salt-avoidance allocation strategy under highly saline-alkaline conditions. This approach enables the maintenance of growth dominance under saline-alkaline conditions via gradient resource utilization.