Wood Ash Fertilization on Structural Characteristics and Chlorophyll Index of Tropical Forage Grasses

Abstract

The appropriate nutrient supply via fertilization is essential for an adequate plant growth and development. The objective of this study was to evaluate the structural characteristics and chlorophyll index of Marandu and Xaraes grasses fertilized with wood ash. The experiment was conducted in a greenhouse; the experimental design was entirely randomized, with 12 treatments and six replications arranged in a 2 × 6 factorial scheme: two forage grasses (Marandu and Xaraes) and six wood ash doses (0; 3; 6; 9; 12; and 15 g · dm -3 ). Each plot was composed of pots with 7 dm3 soil and five plants. Soil moisture was maintained by the gravimetric method at 60% of the maximum soil water retention capacity. Three harvests of the plant aerial part were performed at 30-day intervals. The evaluated characteristics were plant height, leaf number, tiller number, and chlorophyll index. Results were submitted to the variance analysis by F test and, after verification of the significant effects on Marandu and Xaraes characteristics, were also submitted to Tukey test; the wood ash doses were evaluated according to the regression analysis at 5% probability. Wood ash doses ranging from 10.15 to 15 g · dm -3 resulted in quadratic responses of plant height, leaf number, and tiller number for both Marandu and Xaraes grasses. The highest values of chlorophyll index derived from wood ash doses of 9.44 and 10.92 g · dm -3 , with increments greater than 50%, 25%, and 9% at the first, second, and third harvests, respectively. The wood ash, when used as a fertilizer, improves structural characteristics and increases chlorophyll indices of Marandu and Xaraes grasses cultivated in Cerrado Rhodic Hapludox.