Paspalum notatum growth and pigment content in response to the application of herbicides

Abstract

Bahiagrass (Paspalum notatum) is a poacea resistant to trampling, water restriction and low soil fertility; however, it requires frequent cutting to eliminate the biomass excess it produces. To inhibit the growth of turfs and to avoid or delay cutting, growth regulators and herbicides have been tested. The goal of this work was to evaluate the potential of three herbicides as growth regulators on bahiagrass, and their influence on growth and chloroplast pigment content. The experimental design was in randomized blocks, in split-plot scheme, with three herbicides (glyphosate, isoxaflutole and tembotrione) and five doses (0, 68, 136, 272, 544 g a.e. ha^-1; 0, 24, 48, 96, 192 g a.i. ha^-1 and 0, 13, 26, 52, 104 g a.i. ha^-1), respectively, with four replications. The following characteristics were evaluated: phytointoxication, dry mass, grass height and chloroplast pigment content. Data were submitted to analysis of variance and, when significance was observed, the regression test was performed, up to the second degree, separately for each herbicide. Herbicides demonstrated effectiveness in controlling turf size; however, the phytotoxic effect was observed with the increase of the doses and a damage in the aesthetic aspect of the grass. Isoxaflutole has greater potential to be used as a growth reducer on bahiagrass, due to the low necessary dose to reduce height and to low phytointoxication. The content of chloroplast pigments is changed singularly for each used herbicide, and it has a direct relation with the dry mass of leaves.