Abstract
Background: Few species of tropical shrubs potentially produce biomass to replace fossil fuels for heat production and electricity. The aims of this study were to determine the growth and nutrient status of leaves of several types of energy crops from tropical shrub species with NPK fertilizer application. Methods: Randomized block design was used with ten replications of four levels of fertilizer treatment: T0 = 40 g, T1 = 80 g, T2 = 120 g and T4 = 160 g per plant. Results: The results indicated that fertilization increased plant growth and the quantity of nutrients in leaves. The plants accumulated a lot of potassium, followed by nitrogen and phosphorus. The species of tropical shrubs with the best growth were Vernonia amygdalina, Calliandra calothyrsus and Gliricidia sepium, which are all potentially cultivated as sustainable energy crops. Conclusions: Serious attention must be paid to the availability of soil nutrients in order to sustain the cultivation of these plants.