Nitrogen, Potassium, and Nitrate Concentrations of Lettuce Grown in a Substrate with KNO3-Enriched Zeolite

Abstract

Zeolite minerals improve the efficiency of nutrient use by plants by helping to regulate the release of nitrogen and nitrate accumulation in tissues. The main objectives of this research were to evaluate effects of the addition of zeolite enriched with potassium nitrate (KNO3) on the nitrate (NO3-N) and potassium (K) levels of lettuce shoot. Treatments arranged in a completely randomized block design with three replications comprised two types of the natural zeolite: concentrated zeolite, zeolite + KNO3, and a control grown in substrate fertilized with a nutrient solution without zeolite supply. Four levels of enriched zeolite were tested (20, 40, 80, and 160 g per pot). Nitrogen, K, and NO3-N data were evaluated and response equations were fitted. The results indicated that zeolite enriched with KNO3 released the macronutrients N and K to lettuce plants. The concentrations of total N, total K, and NO3-N increased with zeolite levels, and there was a positive correlation between total N and NO3-N forms. To keep levels of NO3-N− in shoots within the safe limit for human consumption, based upon the regression equation for NO3-N the recommended dose of KNO3-enriched zeolite should be up to 78 g per plant.