The objectives of the project are to develop time-based nutrient bioaccumulation and plant chemical profiles over the course of shoot flushes. Current studies include Ruby Red on Swingle and Volkamer rootstocks in peat-based media. Progress report: nitrate-nitrogen treatments 0, 70, 140, 280, and 560 ppm were imposed on Ruby Red grapefruit budded on Swingle and Volkamer rootstocks growing in 15 gallon containers. Growth index, SPAD, and foliar nutrients were monitored over the course of the study. As a mean of all sampling events, growth index was not significant for treatment but was significant for rootstock with Swingle producing trees with larger canopies. SPAD, an indirect measurement of chlorophyll, was not significant for rootstock but was significant for nitrate-nitrogen treatment with SPAD (leaf greeness) increasing with nitrate-nitrogen treatment level. In general, foliar nutrient accumulation increased with nitrate-nitrogen treatment, but what was more interesting was that nitrate-nitrogen treatment had no affect on foliar accumulation of the micronutrient metals copper, nickle, or zinc. These studies are building on previous work on Swingle, Volkamer, and Cleopatra (not budded) where we discovered that nutrient uptake for both macro and micro nutrients occurred 7 to 14 days prior to flush, and that for all nutrients determined, copper and manganese were the most erratic and increased the greatest in relations to shoot flush, respectively, and that nitrate-nitrogen (100%), in solution culture, promoted shoot flush compared to treatments that contained some ammonium-nitrogen (25%). Growers will be able to use this information to better time the application of fertilizers for maximum nutrient use efficiency and possibly for controlling the intensity and duration of shoot flush. Using fertilizers more efficiently has both economic and environmental benefits, and manipulating flush may reduce the risk of trees to plant pathogen infection and insect pests as new flush leaves are most susceptible to these threats.