Características morfológicas de gramas em resposta à aplicação de trinexapac-ethyl

Abstract

RESUMO -O presente trabalho teve como objetivo avaliar os efeitos da aplicação de duas doses de trinexapac-ethyl sobre a morfologia das espécies de gramas São Carlos (Axonopus compressus), Batatais (Paspalum notatum), Santo Agostinho (Stenotaphrum secundatum) e Esmeralda (Zoysia japonica). Os gramados foram cortados à altura de 3 cm no início do experimento e 20 dias depois. Após cada corte, foram realizadas duas aplicações sequenciais de trinexapac-ethyl nas doses de 56,5 + 56,5 e 113,0 + 113,0 g ha -1 , além de uma testemunha sem aplicação, para cada espécie avaliada. O delineamento experimental utilizado foi o de blocos ao acaso com quatro repetições. A redução do crescimento foi avaliada por meio da altura das plantas. Semanalmente, o número e altura de inflorescências foram avaliados por amostragem, realizada em 0,25 m 2 no centro das parcelas; no final do experimento, avaliou-se a massa seca total. A aplicação do trinexapac-ethyl retardou o crescimento vegetativo e a emissão das inflorescências, assim como não provocou danos aparentes nos gramados. O uso do trinexapac-ethyl nos gramados avaliados pode reduzir a necessidade de cortes em até 55 dias após a segunda aplicação.Palavras-chave: regulador vegetal, Axonopus compressus, Paspalum notatum, Stenotaphrum secundatum e Zoysia japonica.ABSTRACT -The aim of this research was to evaluate the effects of the sequential application of two rates of trinexapac-ethyl on the morphology of the following turf grass species: Broadleaf Carpetgrass (Axonopus compressus), Bahiagrass (Paspalum notatum), St. Augustinegrass (Stenotaphrum secundatum) and Korean Lawngrass (Zoysia japonica). The treatments used were trinexapac-ethyl with two sprays applied at 20 day interval at two different rates (56.5 + 56.5 and 113.0 + 113.0 g ha -1 ) and a control without spraying, for each species. The turf grasses were cut at the height of 3 cm, and sprayed after the treatments. Twenty days after the first treatment application, the plots were cut again and the second treatment application was carried out. The experiment was arranged in a completely randomized block design with four replications. Growth reduction was evaluated based on the height of the plants. Inflorescence number and height were weekly evaluated by sampling, carried out in 0.25 m 2 in the center of the plots. Total dry matter was evaluated at the end of the experiment. Ttrinexapac-ethyl application delayed growth and inflorescence emission and did not cause any visual damage to the turf grasses. Trinexapac-ethyl application can reduce the need of cuts for a period up to 55 days after the second application.

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

“…Table 4 that the application of trinexapac-ethyl reduced the average height of Bermuda grass (Cynodon dactylon), which reached values close to 50%, and all doses were effective and similar. These results corroborate those found by McCullough et al (2007), Costa et al (2009) andMaciel et al (2011). Regarding the number of flower stems, reductions were observed from the dose of 226 + 226 g ha was applied, that is to say, a reduction of 52%, 70%, 69% and 73%, respectively (Table 4).…”

“…Table 3 shows that the trinexapac-ethyl growth regulator, regardless of the dose and number of applications, significantly reduced the number and height of flower stems of the Japanese lawn grass; these reductions were less accentuated by the application of the 113 + 113 g ha for the height of these stems. Some studies have shown that, with the application of trinexapac-ethyl, there may be a decrease or delay in the emission of inflorescences, maintaining the aesthetics of the lawn for a longer time (Johnson, 1990;Fry, 1991;Costa et al, 2009;Mittlesteadt et al, 2009;Marchi et al, 2013b). Type II growth regulators, which is the case of trinexapac-ethyl, are not efficient in suppressing the emission of floral stems because they interfere with the biosynthesis of gibberellins, thereby reducing cell elongation (Marchi et al, 2013a;Marchi et al, 2014); however, in this study, with Japanese lawn grass, significant effects resulting from its application were observed at high doses.…”

Effects of plant regulators on the growth and flowering of Saint Augustine grass plants

“…Several research works have shown that trinexapac-ethyl when sequentially applied to TifEagle bermudagrass plants may retard and/or reduce the emission of inflorescences and prolong the lawn visual aspect making unnecessary a new mechanical plant cutting (JOHNSON, 1990;FRY, 1991;COSTA et al, 2009;MITTLESTEADT et al, 2009). McCullough et al (2007 reported a reduction of the order of 81% in the number of floral rachises when three doses equivalent to 50 g ai ha -1 of trinexapac-ethyl were applied at intervals of seven days on TifEagle bermudagrass (Cynodon dactylon × C. transvaalensis Burtt-Davy).…”

Growth and flowering inhibition of Paspalum notatum with application of trinexapac-ethyl and prohexadione-calcium

“…ha -1 . However, different results were reported by Costa et al (2009), who observed that the sequential application of trinexapac-ethyl (113 + 113 g a.i. ha -1 ) promoted reduction of only 28.5% in the emergence of flower rachises of P. notatum in the period of 70 days after the second application.…”