Response of cowpea to phosphorus on an Oxisol with special reference to dry matter production and mineral ion contents
Keywords:Phosphorus, Oxisol, Brazil, Dry matter production, Nutrient distribution, Vigna unguiculata (L.) Walp., Cowpea
AbstractThe objective of this investigation was to evaluate the effects of P fertilization on growth, yield and nutrient uptake patterns in cowpea. Phosphorous application significantly increased growth, yield and yield components. The critical soil-applied P levels was 160 mg kg-1 of soil for seed yield and 142-150 mg P kg-1 of soil for yield components. The critical level of soil P extracted for seed yield was 40 mg kg-1 of soil and the plant tissue critical level was 0.13% at harvest. Analyses of nutrient distributions in different plant parts showed that cowpea roots retained maximum Fe and minimum K and Ca. Tops retained maximum Ca, almost 50% of P, K and Mg and 65% of Mn; large amounts of P, K, Zn and Cu were translocated to seeds. Pot husks contained a high level of Mg and Cu. Phosphorous fertilization decreased the concentrations of K, Zn and Cu in plant tops. Magnesium concentration was increased with P fertilization; Ca and Fe concentrations were unaffected.