Metabolism and efficiency of phosphorus utilization during senescence in pepper plants: Response to nitrogenous and potassium fertilization

Application rates of nitrogen and potassium were studied in relation to par ameters of phosphorus metabolism in pepper plants (Capsicum annuum L. cv. L amuyo) during senescence. All plants, grown under controlled conditions in a greenhouse, were 2 administered 4 rates of nitrogen (N) as NH4NO3 (N1: 6 g N m(-2), 12g Nm(-2), N3: 18 g N m(-2), N4: 24gN m(-2)) and three rates of potassium (K) as K2SO4 (K1: 4 g K m(-2), K2: 8 g K m(-2), K3:12 g K m(-2)) at the onset of flowering. The plants treated with the N2 treatment had th e highest leaf concentrations of phosphorus (P) forms (inorganic P, lipid P , DNA-P, RNA-P, proteic P and total P), whereas the concentrations of organ ic and soluble P were the lowest. In these plants potassium fertilization e xerted a negative effect on the concentrations of the different P forms, al though yield significantly rose with K applied, reaching the highest values at K3. Finally, acid phosphatase activity and carbohydrate proved to be go od indicators of the nutritional status of P.