Concurrent Increases in Root Phosphorus Acquisition and Leaf Phosphorus Resorption Underpin Enhanced Phosphorus Economy in Chickpea During Reproductive Development.

Abstract

Phosphorus (P) acquisition and leaf P-use strategies are critical for reproductive success and productivity, yet, their developmental association during the reproductive phase remains unclear. Five chickpea accessions contrasting in P-remobilisation efficiency (PRE) were grown in a temperature-controlled glasshouse under moderate P deficiency. Root P-acquisition traits (rhizosheath carboxylates and rhizosheath acid phosphatase activity) and leaf P-use traits (PRE, photosynthetic P-use efficiency (PPUE), P fractions, and leaf acid phosphatase activity) were measured. Phosphorus acquisition substantially increased during reproduction compared with the vegetative stage, with greater carboxylates recovered from the rhizosheath and higher rhizosheath acid phosphatase activity. Root nitrogen (N) and P concentrations increased by 108% and 54%, respectively. Leaf PRE increased by 28%, with higher resorption efficiency across most P fractions, whereas N-resorption efficiency was stable. Although area-based photosynthetic rate increased by 34%, PPUE did not, and we observed no trade-off between PPUE and PRE. Leaf thickness and leaf mass per area increased by 22% and 34%, respectively, partially explaining the faster photosynthetic rate. Concurrent we also observed increases in transpiration, and this may be associated with increased photosynthetic capacity. These results reveal coordinated increases in root P acquisition and leaf P remobilisation during reproduction, likely driven by stronger sink demand.