Carbon dioxide on the penetration and distribution of phosphine through wheat

Aluminum phosphide was applied with and without CO2 (dry ice) to the top of 4,15-m towers containing soft red winter wheat. Amounts were calculated based on the total volume of the towers to produce theoretical concentrations of 1.74 g PH3/m3 and 5% (by vol) CO2. Concentrations of PH3 and CO2 were determined periodically during the 6-d experiments. When CO2 Was applied with aluminum phosphide, phosphine penetrated the column of wheat faster and accumulated in higher concentrations than when aluminum phosphide was applied alone. Effects of the CO2 were more pronounced as the depth in the column increased. At the end of the exposure time, concentrations of phosphine were more evenly distributed when CO2 was applied with the aluminum phosphide