Glyphosate as Growth Regulator for Bahiagrass and Broadleaf Carpetgrass

Abstract

The objective of this work was to evaluate the effect of glyphosate herbicide as growth regulator on two turfgrasses bahiagrass and broadleaf carpetgrass. The experiments were conducted in a greenhouse, using a completely randomized design, with 10 glyphosate rates (0, 5.625, 11.25, 22.5, 45, 90, 180, 360, 720, and 1.440 g a.e. ha-1) and four replicates. Bahiagrass and broadleaf carpetgrass plants were transplanted to 2 liter pots filled with a clayey soil. Phytotoxicity and green cover index (GCI) were evaluated through digital analysis; plant height at 7, 14, 21, and 28 days after application (DAA); and dry biomass of cuttings at 28 DAA. The glyphosate rates of 5.625 to 22.5 g a.e. ha-1 (for bahiagrass) and up to 90 g a.e. ha-1 (for broadleaf carpetgrass) reduced the plant growth, without affecting the plant visual quality phytotoxicity, GCI, and dry biomass in the evaluated periods. Contrastingly, rates equal to and above 45 g a.e. ha-1 (for bahiagrass) and equal to and above 180 g a.e. ha-1 (for broadleaf carpetgrass) caused phytotoxic effects in all evaluated periods and affected negatively plant height, GCI, and dry biomass, denoting the sensitivity of these grass species to these glyphosate rates. The digital image analysis allowed the verification and quantification of the effects of the herbicides on turfgrasses.

Paclobutrazol as growth regulator in Bahiagrass

“…Thus, by creating a more compact leaf, the application of Paclobutrazol ends up causing the turfgrass to leave its rhizomes exposed, which reduces the green density of the lawn. Dias et al (2019) also observed reduction in green visual quality of Bahiagrass after application of glyphosate as growth regulator from the dose of 45 g a.e. (acid equivalent) ha -1 .…”

“…Plant regulators are gaining importance in lawn management programs, as they suppress vegetative growth without impairing their visual quality and without promoting phytointoxication, discoloration or leaves thinning (McElroy, 2012;March et al, 2013;Gazola et al, 2019). However, there are no registered products for lawns in Brazil for this purpose (Dias et al, 2019;Gazola et al, 2019). An alternative would be the use of Paclobutrazol, which is a regulator already studied and registered for other crops such as mango, tomato (Syngenta, 2019), and registered for turfgrass in the European Union (Semillas Fitó, 2010) and in the USA (McElroy, 2012).…”

“…Studies on Brazilian conditions for growth control in Bahiagrass have been published in recent years (Marchi et al, 2016;Marchi et al, 2017;Barbosa et al, 2017;Dias et al, 2019), however none of them use Paclobutrazol as a growth regulator. In this context, the objective of the present study was to evaluate the use of Paclobutrazol doses as growth regulators in Bahiagrass.…”

Paclobutrazol and phenoxaprope-P-ethyl potential as growth regulator in Carpet grass Plus®

“…However, according to Kreuser (2015), mowing may be difficult due to the embankment slope, and also, resulting in higher expenses (Santos and Castilho, 2018). Thus, an alternative to this management would be the use of plant growth regulators (Dinalli et al, 2015;Marchi et al, 2017;Dias et al, 2019;Gazola et al, 2019). It has the function slower the plant growth, without causing visible damage, such as necrotic spots of phytotoxicity, discoloration or thinning, but allowing the maintenance of its aesthetics and characteristic green colour (Gazola et al, 2016;Dias et al, 2019).…”

“…However, in Brazil does not have any product registered as a growth regulator for grass, so it is necessary to search for more information (Dias et al, 2019). Paclobutrazol is a well-studied regulator, and registered for several species of grass in the European Union (Semillas Fitó, 2010) and in the USA (McEloroy, 2012).…”