Nutritional status, production and fruit quality of West Indian cherry fertigated with nitrogen and humic substance

Abstract

Information on humic substances (HS) associated with nitrogen fertilization in West Indian cherry is scarce in the literature. The use of soil conditioners, such as HS, can increase the efficiency in the absorption of nutrients, especially N. Therefore, the present study aimed to evaluate, in two production cycles, the fruit quality, yield and nutritional status of West Indian cherry as a function of fertigation with nitrogen (N) and HS in Petrolina-PE, Brazil. The experimental design was in split plots, with treatments distributed in 5 x 2 strips, referring to N doses (50, 75, 100, 125 and 150% of the recommended dose) and HS application (without and with), respectively, with 4 replicates and 3 plants per plot. The N source used was urea (45% N) and the HS source used was the commercial product KS100 (Omnia®), from leonardite, monthly applied at dose of 6 g plant-1. Production, yield, indices of chlorophyll a, chlorophyll b and total chlorophyll, and leaf contents of N, P, K, Na, Ca, Mg, Fe, Mn and Zn were determined. Fruits were evaluated for: pH, vitamin C, soluble solids (SS), titratable acidity (TA) and SS/TA ratio. Except for leaf N content, which increased linearly with the applied doses, the leaf contents of nutrients, production and yield of West Indian cherry showed a stochastic pattern as a function of the increase in N availability and HS application. West Indian cherry plants cultivated and fertilized according to the recommendation for the crop did not respond to the evaluated treatments. Application of humic substances and N doses did not alter the post-harvest quality of West Indian cherry fruits.