Fertilizer P use efficiency in wheat under elevated atmospheric CO2 and temperature in subtropical India: a 32P tracer study

A phytotron experiment was undertaken in which wheat was grown as a test crop under two levels of atmospheric CO2: ambient (385, μmol mol-1) and elevated (650, μmol mol-1); two levels of temperature: ambient (ambient air temperature of rabi season in Subtropical India) and elevated (ambient+3 deg C); and three levels of P: zero (control), 100% and 200% of recommended P dose to wheat. There were significant increases in total P and fertilizer P uptake by plant under singly elevated CO2 as well as concurrently elevated CO2 and temperature, with no significant change in %Pdff. As a consequence, fertilizer P use efficiency (PUE) also showed significant improvements both under the elevated CO2 alone as well as under combined elevation of CO2 and temperature. While this increase in fertilizer PUE was a welcome change under the projected levels of CO2 and temperature, low efficiency at higher doses of P application still remained a matter of concern. (author)