Susceptibility of Perennial Tropical Forage Plants to Glyphosate Herbicide in Integrated Crop-Livestock Farming Systems

MACHADO, L.A.Z.; COMUNELLO, É.; CECATO, U.; CONCENÇO, G.

doi:10.1590/S0100-83582018360100105

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Article • Planta daninha 36 • 2018 • https://doi.org/10.1590/S0100-83582018360100105 copy

Susceptibility of Perennial Tropical Forage Plants to Glyphosate Herbicide in Integrated Crop-Livestock Farming Systems

Suscetibilidade de Forrageiras Tropicais Perenes ao Herbicida Glyphosate em Sistemas Integrados de Produção Agropecuária

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT:

The purpose of this study was to evaluate forage plant susceptibility in Urochloa ssp. and Megathyrsus maximus with two glyphosate herbicide doses, to increase the efficiency of integrated crop-livestock farming systems. A randomized block design was adopted, in a split-plot arrangement, with six replications. In the main plots, the following treatments were established: Urochloa ruziziensis, U. decumbens, U. brizantha cvs. Xaraés, BRS Piatã and BRS Paiaguás, Megathyrsus maximus cvs. Aruana and BRS Tamani; in the subplots, there were doses of glyphosate herbicide; 0.72 and 1.44 kg a.e. ha-1. The estimated control percentage was consisted of a grading scale from zero (fully living tiller) to 100 (fully dead tillers), assigned 7; 14; 21 and 28 days after herbicide application. The 0.72 kg a.e. ha-1 glyphosate dose was not effective for forage control, but it was possible to identify the most susceptible genotypes, such as U. ruziziensis and BRS Paiaguás. The 1.44 kg a.e. ha-1 dose was satisfactory in controlling (³80%) the grasses U. ruziziensis, U. brizantha cv. BRS Paiaguás and M. maximum cv. Aruana at 17, 18 and 18 days of desiccation intervals, respectively. In conclusion, the susceptibility of forage plants to herbicide glyphosate varies among species and cultivars. U. ruziziensis, BRS Paiaguás and Aruana grasses are desiccated with reduced herbicide doses and short desiccation intervals, and can contribute to the diversification of the forage used in integrated crop-livestock farming systems.

Keywords:
Brachiaria; desiccation; Megathyrsus; Panicum; Urochloa

Sociedade Brasileira da Ciência das Plantas Daninhas Departamento de Fitotecnia - DFT, Universidade Federal de Viçosa - UFV, 36570-000 - Viçosa-MG - Brasil, Tel./Fax::(+55 31) 3899-2611 - Viçosa - MG - Brazil
E-mail: rpdaninha@gmail.com

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[1] * Corresponding author: <luis.zago@embrapa.br>

Forage plant	Dose	Equation	R²
U. ruziziensis	0.72	$y = - 29.3333 + 8.2262 x - 0.1616 x^{2}$	0.785
U. ruziziensis	1.44	$y = - 39.9583 + 12.2988 x - 0.2696 x^{2}$	0.944
U. decumbens	0.72	$y = - 16.6071 + 4.5133 x - 0.1028 x^{2}$	0.703
U. decumbens	1.44	$y = {- 0.1108 x}^{2} + 6.4082 x - 20.786$	0.890
U. brizantha cv. Xaraés	0.72	$y = - 11.1667 + 2.9786 x - 0.0697 x^{2}$	0.620
U. brizantha cv. Xaraés	1.44	$y = - 8.8333 + 2.3881 x$	0.796
U. brizantha cv. BRS Piatã	0.72	$y = - 11.1667 + 2.9786 x - 0.0697 x^{2}$	0.62
U. brizantha cv. BRS Piatã	1.44	$y = - 13.1250 + 3.2036 x - 0.0315 x^{2}$	0.796
U. brizantha cv. BRS Paiaguás	0.72	$y = - 31.0714 + 7.2694 x - 0.1224 x^{2}$	0.885
U. brizantha cv. BRS Paiaguás	1.44	$y = - 44.6071 + 10.8112 x - 0.2136 x^{2}$	0.942
M. maximus cv. Aruana	0.72	$y = - 15.1250 + 4.4964 x - 0.0740 x^{2}$	0.641
M. maximus cv. Aruana	1.44	$y = - 42.0000 + 11.0452 x - 0.233 x^{2}$	0.874
M. maximus cv. BRS Tamani	0.72	$y = - 8.5417 + 2.5774 x - 0.0638 x^{2}$	0.604
M. maximus cv. BRS Tamani	1.44	$y = - 0.5417 + 0.8488 x + 0.0383 x^{2}$	0.818

Forage plant	Shoot biomass		Dry matter percentage		Control percentage
	0.72	1.44	0.72	1.44	0.72	1.44
	(kg ha^-1)			(%)
U. ruziziensis	1,277 d	1,209 d	61.1 a B	83.5 a A	76.0 a B	95.5 a A
U. decumbens	1,760 cd	1,691 bcd	42.9 bc B	64.5 b A	28.5 c B	73.2 b A
U. brizantha cv. Xaraés	2,687 a	2,230 ab	37.9 c B	56.3 bc A	14.2 d B	58.0 c A
U. brizantha cv. BRS Piatã	2,530 ab	2,692 a	41.8 bc B	52.3 c A	18.3 cd B	52.8 c A
U. brizantha cv. BRS Paiaguás	2,031 abc	1,978 bc	68.1 a B	76.0 a A	77.5 a B	93.7 a A
M. maximus cv. Aruana	1,962 bc	1,534 cd	49.0 b A	65.4 b A	52.5 b B	86.2 a A
M. maximus cv. BRS Tamani	2,542 ab	2,297 ab	33.7 bc A	48.4 c A	14.2 d B	54.2 c A