Nutritional status and production of noni plants fertilized with manure and potassium

Abstract Noni is a fruit species cultivated around the world, including Brazil however, scientific information about its nutritional status are scarce, thus justifying the need for more research on this topic to enhance its productive yield. This study aim is to evaluate both the mineral foliar composition and the productivity of noni plants cultivated in soil with cattle manure and potassium (K). The experiment was conducted from July 2012 to November 2013 at the Universidade Federal da Paraíba, Municipality of Bananeiras, Paraíba State. Treatments were organised according to a 5 × 2 factorial design involving five doses of KCl (0; 13.2; 37.5; 61.5; and 69.6 g plant-1) in soil without cattle manure and with 4 kg plant-1, in randomized blocks, with four repetitions and three plants per plot. The number of noni fruits harvested by plants fertilized with cattle manure increased from 51 to 70 fruits plant-1. Compared to coffee trees, noni plants were adequately supplied with nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron and zinc, but they were deficient in boron and manganese. The application of cattle manure to soil promoted contents of phosphorus and potassium in foliar samples, positively affecting the fruit formation and the production of noni plants.