Determination of Critical Tissue Phosphorus Concentration in Mungbean and Urdbean for Plant Diagnostics

Abstract

A pot experiment was conducted to study the effect of phosphorus (P) nutrition on mungbean and urdbean genotypes and to determine the critical concentration of tissue phosphorus at different growth stages for plant diagonostic and P management. There were eight treatments consisting of different levels of P added in the form of monopotassium phosphate (KH2PO4). Destructive plant samples were taken to determine tissue P concentration and plant dry matter at different growth stages. Plant tissue P concentration was found highly correlated with dry matter production in mungbean (r2 = 0.84–0.98) and urdbean (r2 = 0.98–0.998) at corresponding sampling period throughout the growth stages. Considerable variation was observed in critical P concentration with genotypes and leaf position in mungbean and urdbean. Critical P concentration varied between 0.45–0.49 in mungbean and 0.45 to 0.57 in urdbean at early stages of crop growth, and these values declined sharply with advancement in crop growth.