IMPACTO DEL NITRÓGENO SOBRE EL ESTADO NUTRICIONAL DEL FÓSFORO Y SU PRINCIPAL BIOINDICADOR: RESPUESTA EN RAÍCES Y HOJAS DE PLANTAS DE FRIJOL EJOTERO

Abstract

The objective of the present work was to determine the effect of different doses of nitrogen (N) on the nutritional status of phosphorus (P) in roots and leaves of green bean plants (Phaseolus vulgaris L. cv. Strike), and also to examine the response of acidphosphatase activity as the main bioindicator of P. Nitrogen was applied to the nutrient solution as NH4NO3 and increasing doses of: N1 = 1.5 mM, N2 = 3.0 mM, N3 = 6.0 mM, N4 = 12.0 mM, N5 = 18.0 mM, and N6 = 24.0 mM of N were added. The results indicate that both deficient and toxic N doses were characterized by the lowest level of total, inorganic and organic phosphorus, as well as the highest activity of acid phosphatase; these effects are due to the direct influence between N and P levels. Treatment N4 presents the highest levels of the diverse fractions of P and the lowest activity of acid phosphatase. Additionally, it was found that the highest proportion of P in roots and leaves are in the forms of P-inorganic (Pi) and P-organic. These represented more than 65 % of total P, so it can be said that they represent the main forms of phosphorus in green bean plants. Finally, it should be noted that acid phosphatase activity was significantly correlated with Pi, which indicates that it can be used as a good indicator of the nutritional status of P in the roots and leaves of green bean plants.