Evaluation of the nutritional status of the bean plant (Phaseolus vulgaris L.) grown in nutrient solution under varying levels of N, P and K

Abstract

Bean plants (Phaseolus vulgaris L., cv. Carioca) were grown in nutrient solution in the presence of the following concentrations of N, P and K, respectively, in milimoles per liter: 16-2-6; 4-2-6; 1,6-2-6; 16-0,5-6; 16-0-6; 16-2-3 and 16-2-0,6. The remaining macro and all micronutrients were supplied at the same rates to all plants. The nutritional status was assessed by the following techniques: foliar diagnosis (determination of total N, P and K and of the nitrate-N and soluble phosphate concentration) and nitrate reductase activity (RNO3). All methods proved to be suitable, except in the case of P. Higher correlations with bean production, however, were obtaind for total concentration of N and K, nitrate-N, and RNO3 activity.