Response of heart-of-palm from peach palm (Bactris gasipaes) to nitrogen in Costa Rican Andisols

Abstract

 The effect of bimonthly fractionated N fertilization on heart-of-palm plantations was evaluated using an ammonium nitrate source at levels of 0, 50, 100, 200 and 400 kg ha^-1 of N. A complete randomized block design was used, with 3 replicates, on an Andic Dystrudept of the Experimental Station Los Diamantes, Guápiles, Pococi, Limón. The experimental plot was 80 m² with 4 rows 10 m long, 2 m between rows, and 1 m between plants. The Tucurrique spiny variety was used in a 4 year-old plantation, totally pruned and allowed to free growth during 2 years before beginning the trial. The study period was 1 year with monthly reaping in order to evaluate: number of heart-of- palm ha^-1, average weight of heart-of-palm reaped, height, basal diameter, and average number of leaves of the plants reaped. The effect of fertilization on nutrient availability in the soil was studied, as was their content in leaves 3 and 5. Significant differences between treatments were found only for the number of heart-of-palm ha^-1 and their average weight. There were significant positive correlations between yield and growth, except for the number of leaves, which correlated only with the basal diameter. The application of high levels of N caused increases in soil acidity, acidity saturation, Mn and Fe contents, and decreases in pH and Ca, Mg and organic matter content in the soil. At a foliar level, a higher N content in leaf 3 than in leaf 5 was found, and Ca and Mg decreased as N levels increased. Positive correlations were found between N and P contents for all leaves analyzed. Critical N foliar levels of 2.88% for leaf 3, and 2.37% for leaf 5, were established, and these values were associated with relative yields of 73 and 80% of heart-of-palm ha-1, respectively. The application of 150 kg ha^-1 of N allowed to reach the critical levels of N for leaf 3 as well as leaf 5; however, an application of 200 kg ha^-1 of N is being recommended for commercial heart-of-palm plantations in conditions similar to the present experiment.