Mineral nutrition of Andropogon gayanus Kunth var. bisquamulatus (Hochst) Hack. III - internal and external critical phosphorus levels

Abstract

Andropogon gayanus var. bisquamulatus seed were directly sowed in pots containing finely ground quartz as a substrate and maintened in the greenhouse. The plants received a nutrient solution lacking in phosphorus and in which the following levels of phosphorus were added, in mg/l: 0.0017; 0.007; 0.030; 0.120; 0.480; 1.940; 7.750 and 31.80. The critical level of phosphorus correspondent to the maximum production of dry matter at 75 days was 0.022% and the external level was 0.480 mg of P/l.