Direct foliar uptake of phosphorus from desert dust

Phosphorus (P) scarcity constrains plant growth in many ecosystems worldwide. In P-poor ecosystems, the biogeochemical paradigm links plant productivity with the deposition of P-rich dust originating from desert storms. However, dust P usually has low bioavailability and is thought to be utilized solely via roots. We applied desert dust on the leaf surface of P-deficient and P-sufficient wheat, chickpea and maize to test the feasibility of direct foliar uptake of dust-P and investigate its related acquisition mechanisms. Foliar dust doubled the growth of P-deficient chickpea and wheat, crops originating near the Syrian Desert. P deficiency stimulated several leaf modifications that enabled acquisition of up to 30% of the sparingly soluble dust-P that is conventionally perceived as unavailable. These modifications increased foliar dust capture, acidified the leaf surface and, in chickpea, enhanced exudation of P-solubilizing organic acids. Maize (originating far from deserts) displayed only a marginal response to dust. The dramatic response of chickpea and wheat in comparison to maize suggests that plants that evolved in dust-rich ecosystems adopted specialized utilization strategies. Interestingly, the abovementioned foliar responses are comparable to known P uptake root responses. Given that P limitation is almost universal, a foliar P uptake pathway will have significant ecological and agricultural implications.

Automated summary

The study found that certain crops like chickpea and wheat can significantly enhance growth by directly absorbing phosphorus from dust on their leaf surfaces, especially in phosphorus-deficient ecosystems. This foliar phosphorus uptake pathway may have important ecological and agricultural implications.