Sorghum bicolor is an important grain species used for food and feed production, where P is a key element/nutrient in grain production. The effect of increasing phosphorus doses to grain sorghum in Cerrado soil with sandy texture and low fertility in Cerrado conditions was evaluated. The study was conducted at the Pântano Farm, Jataí, Goiás, Brazil. The sorghum cultivar used was AG 1085. The doses of 0 (control), 40, 80, 120, and 160 kg ha-1 of P2O5 were used, whose source was triple superphosphate 46% of P2O5, with five replications each, designed in random blocks. The evaluated variables were stem length, stem diameter, leaf area, shoot dry mass, leaf phosphorus content, nutrient accumulation, fertilization efficiency, chlorophyll a, and chlorophyll b. For the variables shoot dry mass in (g plant-1), leaf phosphorus content, dry mass expressed in (kg ha-1), and chlorophyll b (CFI), the effect for the application of P doses in cultivar had a linear effect. The analysis of variance of the regression showed a quadratic effect for the variables stem length, stem diameter, leaf area, and phosphorus use efficiency, and for chlorophyll a (CFI), showing a maximum point at the best dose and best values of the variables. The application of Phosphorus influenced the development of the grain sorghum cultivar. The 129 kg ha-1 of P2O5 had the highest efficiency of phosphorus fertilization corresponding to 82.02%.
