NITROGEN CONCENTRATIONS TO MAXIMIZE YIELD AND DECREASE LEACHATE-N IN PEPPERS GROWN IN ROCKWOOL.

Abstract

Many nutrient recommendations for greenhouse production of vegetable crops were developed in northern climates and may not be optimum for Florida production. Experiments were designed to determine nitrogen (N) levels that would maximize yield of rockwool-grown peppers (Capsicum annuum `Midal') in Florida, while reducing nitrate leaching. Treatment 1 plants were fed 60, 90, and 120 ppm N during vegetative, early fruit, and late fruit stages, respectively. Plants in Treatments 2 and 3 were grown at 120 and 175 ppm N, respectively, throughout their entire growth cycle.In Trial 1, increasing N did not affect the number of marketable fruit produced, but increased fruit size. Marketable fruit weight was significantly greater for plants in Treatment 3 compared to Treatment 1. However, there was not a significant difference in marketable yield between plants grown at 120 ppm N and 175 ppm N. Excess N provided by the 175 ppm N treatment caused a 10% increase in total water use and a 250% increase in nitrate-N in the leachate compared to the 120 ppm N treatment. Nitrogen level did not affect blossom end rot (BER) occurrence. Early results of Trial 2 indicate higher occurrence of BER with increasing N concentration and are again showing that 120 ppm N will maximize yield and reduce environmental impact of greenhouse pepper production in Florida.