CRESCIMENTO E NUTRIÇÃO DE MUDAS DE PINHÃO MANSO INFLUENCIADOS PELA SUBSTITUIÇÃO DO POTÁSSIO PELO SÓDIO

Abstract

Due to the oil crisis and concern about the environment, global demand for biofuels has ex- panded rapidly in recent years, so the physic nut has attracted the attention of researchers for the development of research on this specie. The aim of the present work was to verify the effects of the supply of Na to replace potassium nutrition on growth and nutrition of physic nut seedlings. The experiment was conducted in green- house conditions using nutrient solution. We used the completely randomized design in five proportions of replacing K by Na: 100% (T1), 75% (T2), 50% (T3), 25% (T4) and 0% (T5). Thus, the concentrations (in mM) of K:Na in the treatments were: T1 = 0:6.0; T2 = 1.5:4.5; T3 = 3.0:3.0; T4 = 4.5:1.5; T5 = 6.0:0. The sources of K and Na used were KNO3 and NaNO3, respectively. Data were subjected to analysis of variance and means evaluated at Scott & Knott test at 5% probability. The growth and mineral nutrition variables of physic nut seedlings are influenced by the substitution of K by Na, varying according to the characteristic studied. Na re- places partially the K nutrition of physic nut seedlings and establishing a strategy to reduce the doses of K fer- tilizer applied.