Nitrogen fertilization and glyphosate doses as growth regulators in Esmeralda grass

Adubação nitrogenada e doses do herbicida glifosato como regulador de crescimento em grama esmeralda

ABSTRACT

Despite maintaining the green color in turfgrasses, nitrogen (N) fertilization affects shoot growth and, consequently, the frequency of cuts, the main factor in the costs of turfgrass maintenance. Therefore, this study aimed to evaluate N fertilization and the use of glyphosate as a growth regulator in Esmeralda grass (Zoysia japonica Steud.). The experiment was conducted in the field, from August 2014 to July 2015, using a randomized block design in a 5 x 4 factorial scheme with four repetitions and 20 treatments, namely: control (without N), 15 g m^-2 of N in soil without foliar N; 30 g m^-2 of N in soil without foliar N; 15 g m^-2 of N in soil with foliar N (1% urea in 200 L ha^-1) and 30 g m^-2 of N in soil with foliar N combined with glyphosate doses (0, 200, 400 and 600 g ha^-1 active ingredient (a.i.)). The N doses were split into five applications along the year. The following variables were evaluated: height, leaf chlorophyll index and foliar accumulation of nitrogen, phosphorus and potassium. Fertilization with 15 g m^-2 of N in soil without foliar N application, split into five times along the year, was adequate for the turfgrass, while foliar fertilization did not promote benefits. The glyphosate dose of 400 g ha^-1 a.i. was effective in reducing the growth of Esmeralda grass, without compromising its color and promoted less N, P and K accumulation in the leaves, reducing the height and dry matter production.

Key words:
Zoysia japonica Steud; nutrient removal; nutrition