Effect of elevated CO<sub>2</sub> and temperature on phosphorus efficiency of wheat grown in an Inceptisol of subtropical India

Abstract

In a phytotron experiment, wheat was grown under two levels of atmospheric CO2 [ambient (385 ppm) vs. elevated (650 ppm)], two levels of temperature (ambient vs. ambient +3°C) superimposed with three levels of phosphorus (P) fertilization: 0, 100, and 200% of recommended dose. Various measures of P acquisition and utilization efficiency were estimated at crop maturity. In general, dry matter yields of all plant parts increased under elevated CO2 (EC) and decreased under elevated temperature (ET); however, under concurrently elevated CO2 and temperature (ECT), root (+36%) and leaf (+14.7%) dry weight increased while stem (-12.3%) and grain yield (-17.3%) decreased, leading to a non-significant effect on total biomass yield. Similarly, total P uptake increased under EC and decreased under ET, with an overall increase of 17.4% under ECT, signifying higher P requirements by plants grown thereunder. Although recovery efficiency of applied P fertilizer increased by 27%, any possible benefit of this increase was negated by the reduced physiological P efficiency (PPE) and P utilization efficiency (PUtE) under ECT. Overall, there was ~17% decline in P use efficiency (PUE) (i.e. grain yield/applied P) of wheat under ECT.