Leaf chemical and structural properties govern foliar uptake of phosphorus from dust in chickpea

Certain plant species exhibit the capability to absorb phosphorus (P) directly from dust particles deposited on their leaves, particularly in P-limited environments. However, the underlying mechanisms that enable foliar uptake of P from insoluble sources such as dust minerals remain largely unexplored. This study investigates the chemical and structural properties of chickpea leaf surfaces that influence P absorption from dust deposition. We evaluated various chickpea varieties in a series of controlled experiments where P-rich dust was applied to their shoots. The relationship between P acquisition from dust and leaf surface pH, metabolite exudation and trichome density was examined. The tested varieties displayed variability in their leaf structural and chemical properties, which led to significantly different responses to foliar dust application. The most positive dust-responsive variety ('Mekomit') demonstrated a substantial 47–169 % increase in biomass in response to foliar dust application, whereas the most negatively responsive variety ('Cr205') exhibited a 28 % decrease in biomass following application. The positive response to dust was associated with lower leaf surface pH, higher trichome density, and enhanced metabolites exudation. Notably, the positively responsive variety showed increased exudation of sugars and organic acids, predominantly oxalic and malic acids from the leaf surfaces which facilitate P solubilization. These findings underscore the remarkable capacity of certain chickpea varieties to adapt their leaf characteristics in response to P deficiency, allowing them to absorb P from otherwise insoluble sources, such as airborne dust. This insight reveals a fundamental physiological mechanism that enhances our understanding of plant nutrient acquisition strategies under challenging environmental conditions.