Development of Different Grass Species with the Use of the Growth Regulator Trinexapac-Ethyl

The use of synthetic compounds to retard the growth of lawns aims at reducing the number of operations for their maintenance. Thus, the main goal of the present study was to evaluate the effect of different doses of trinexapac-ethyl on the development and rooting of five different grass species. Bahiagrass, St. Augustine grass, Japanese lawn grass, Bermuda grass and, broadleaf carpetgrass were grown in pots of 20 L. The experimental design was completely randomized, with four replications. Trinexapac-ethyl (g ha-1) was applied at doses of 113+113, 226+113, 226+226, 452+113, 452+226, 452+452 in a sequential spraying, and also at single doses of 678 and 904. The second application was carried out 14 days after the first. On the day prior to applications all species were cut at 3 cm height. The phytotoxicity evaluations were performed weekly, and evaluations on plant height, number and height of inflorescences, biomass of aerial parts and roots were carried out 35 days after the second application. The trinexapac-ethyl application was effective in inhibiting the development of the Japanese lawn grass, Bermuda grass and broadleaf carpetgrass when applied in sequential doses higher than 226 g ha-1, or single doses of 678 or 904 g ha-1 and, the visual appearance of lawns was not affected. In the case of St. Augustine grass and Bahiagrass species, the growth regulator did not promoted reduction in the growth of both grass species. RESUMO: A utilização de compostos sintéticos para retardar o crescimento de gramados tem como principal objetivo a diminuição do número de operações para a sua manutenção. Este estudo teve a finalidade de verificar o efeito de diferentes doses de trinexapac-ethyl, aplicadas sequencialmente, sobre o desenvolvimento e enraizamento de cinco espécies de gramas. As gramas batatais, santo agostinho, esmeralda, bermuda tifton 419 e são carlos, foram plantadas em vasos de 20 L. O delineamento experimental utilizado foi o inteiramente casualizado com quatro repetições, onde foram aplicadas as doses do trinexapac-ethyl em g ha-1: 113+113, 226+113, 226+226, 452+113, 452+226 e 452+452 em pulverização sequencial e doses únicas de 678 e 904. Utilizou-se um intervalo de 14 dias entre as duas aplicações. Um dia antes de cada aplicação, todas as espécies foram cortadas a 3 cm de altura. As avaliações de fitointoxicação foram feitas semanalmente, e as avaliações de altura de plantas, número e altura de hastes florais e de biomassa da parte aérea e das ra