INTRODUCTION
Cabbage (Brassica oleracea) is considered the most economically important vegetable species from the Brassicaceae family (Ferreira et al., 2002; Melo and Vilela, 2007; Reis et al., 2017). Farmers report many difficulties in weed management for the cultivation of this species, mainly due to slow crop growth (Moreira et al., 2011), and planting spacing (Cavarianni, 2008; Silva et al., 2011), which favours weed growth, in addition to the small number of herbicides registered (Agrofit, 2018).
Chemical control is one of the most widely used methods within integrated weed management. The use of herbicides is often the best cost-effective option and is also important to avoid crop yield losses (Green, 2014). However, only two herbicides are registered for the cabbage crop in Brazil: glufosinate ammonium, that can crop damage, and trifluralin, which is more recommended for narrow leaf weed control (Powles and Yu, 2010; Agrofit, 2018).
The auxin-mimetic herbicides are used in controlling broadleaf weeds in fallow, grazing, and in crops with narrow leaves such as corn, sugarcane, sorghum and wheat (Brazil, 2018). They act similarly to the natural auxins and are more effective as well as being lethal to the sensitive plants (Pazminõ et al., 2012). The auxinic herbicides are divided into five classes: phenoxycarboxylic acids (for example 2,4-dichlorophenoxyacetic acid); benzoic acids (e.g. dicamba); pyridinacids (e.g. picloram, clopyralid); quinolinecarboxylic acids (e.g. quinclorac); and pyrimidine carboxylic acid (e.g., aminocyclopyrachlor) (Christoffoleti et al., 2015). The structural variation in each herbicide molecule influences the receptor protein binding (Tan et al., 2007) and the rate of degradation within the cell. In Brazil, four substances of this group of herbicides are registered: triclopyr, picloram, dicamba and 2,4-D (Brasil, 2018).
In literature, there are few studies on the selectivity of herbicides for cabbage cultivation, and no studies reporting the use of herbicides in controlling broadleaf weed. Thus, this research aimed to evaluate the tolerance of the cabbage cultivar Astrus Plus to the herbicides 2,4-D and dicamba.
MATERIAL AND METHODS
Two experiments were performed, one in a greenhouse at the Universidade Federal Viçosa - Rio Paranaíba Campus, and the second in a field at Santo Amaro Farm, in Rio Paranaíba, MG, Brazil (Latitude - 19o11’39” S, Longitude - 46o14’37” W, elevation 1,073 m). The cabbage cultivar Astrus Plus was used in both experiments.
Experiment 1 - Greenhouse
This first experiment was performed in order to evaluate the effects of auxinic herbicides on the initial growth of cabbage plants. A completely randomized experimental design arranged in a 2 X 8 + 1 factorial scheme was performed, with the first factor consisting of two commercial products of auxinic herbicides: the 2,4-D (Campeon® 806 g ae Stockton-Agrimor do Brasil Ltda.) and dicamba (Atectra® 480 g ae BASF Corporation). The second factor was composed of eight herbicide doses and a control without the application of herbicide, with four replications. 8.0 L pots filled with Red-Yellow Latosol samples and moistened to the maximum field capacity were used to sow the culture.
Dilutions of 2,4-D and dicamba were prepared in solutions corresponding to 0; 0.5; 1.0; 2.5; 5.0; 7.5; 10; 20; and 100% of the recommended dose of the product for the transgenic soybean crop, which is 1 L ha-1. These doses correspond to 0.005; 0.01; 0.025; 0.05; 0.075; 0.1; 0.2 and 1.0 L ha-1 respectively. The spray volume of the commercial product used was 200 L ha-1.
The application of the doses was performed using a CO2 pressurized sprayer equipped with a hydraulic double-ended spray bar from a single fan jet, model API-11002, operating at a pressure of 3 kgf cm-2, positioned at 50 cm in plant height, when the cabbage plants had two pairs of true leaves.
The evaluation of the plant poisoning at 7, 14, 21 and 28 days after the herbicide application was performed according to the grading scale proposed by the Brazilian Society of Weed Science (SBCPD, 1995), where 0% corresponds to injury absence and 100% plant death.
At the end of the experiment (28 DAA), the aerial and the roots of the plants were separated by cutting the plant parts close to the substrate surface. The roots were removed from the soil and cleaned using water. These plant parts were then placed in a forced air circulation drying oven (70 ± 2 oC) untilaconstant weightwasachieved. The aerial part dry mass (APDM) and the root dry mass (RDM) were determined using a 0.001 g analytical balance.
The dry matter and intoxication were submitted to analysis of variance (ANOVA) and when significant, the treatments were subjected to polynomial regression analysis (p<0.05).
Experiment 2 - Field Farming
This experiment was carried out to evaluate if the auxinic herbicides cause any intoxication and/or changes to the production of cabbage plants. A completely randomized experimental design arranged in a 2 x 6 factorial scheme was performed. The first factor was composed of two auxinic herbicides: the 2,4-D (Campeon® 806 g ae Stockton-Agrimor do Brasil Ltda.), and dicamba (Atectra® 480 g ae BASF Corporation). The second factor was composed of six herbicide doses (0, 0.05, 0.075, 0.1, 0.2, and 1 L ha-1), and the control group without herbicide application, with four replications.
The experimental plots consisted of four 4 m long cabbage lines, with a 0.4 m row spacing between lines and a 0.3 m row spacing between plants, with a total of 62,000 plants per hectare. The dosage preparation and drift simulation were carried out in the same way as proposed in experiment 1.
At 7, 14, 21 and 28 days after application of the herbicide, evaluations of plant poisoning were made according to the grading scale proposed by the Brazilian Society of Weed Science (SBCPD, 1995), where 0% corresponds to injury absence and 100% plant death. At the end of the experiment, at the harvest stage, the production of the cabbage was evaluated. The cabbage heads contained in the useful area (two central rows of each plot) were collected and packed in wooden crates for sale. The heads contained in the crates were then counted and weighed to obtain the number of heads per box, average head mass and an estimation of the cabbage productivity.
The data obtained after evaluating the cabbage productivity was submitted to multivariate analysis (percentage of similarity between variables), in order to select the discriminating variables that could be represented by a single evaluation, considering ideal similarity values above 80%. This analysis was based on the absolute correlation between variables. The software used for the statistical analysis of the data was Minitab® 16.2.1. After discriminating the groups, the means were submitted to descriptive analysis and were then represented in bar graphs. The dry matter data were first submitted to analysis of variance (ANOVA) and then to regression analysis. The data from the plant poisoning obtained were analysed using the nonlinear model proposed by Seefeldt et al. (1995):
[Formula Omitted. Please see PDF.]
where C and D correspond to the minimum and maximum level of the dose response curve respectively; bcorresponds to the slope of the curve around C50; and C50 is the dose response corresponding to a 50% reduction of the plant variable under study.
RESULTS AND DISCUSSION
Experiment 1
No toxicity symptoms were observed in the cabbage plants at 7, 14, 21 and 28 DAA after the application of 2,4-D or dicamba (Figure 1A and B). Differences in dry matter between the aerial parts and roots after the application of these herbicides were also not observed (Figure 2A, B, C and D). These analyses were performed three times each to confirm the reproducibility of the results. From the data obtained, it can be said that the initial growth of the cabbage plants was not affected by the herbicide application. This could be the result of the cabbage being tolerant to this group of herbicides.
[Figure omitted. Please see PDF.]
[Figure omitted. Please see PDF.]
To date, three auxin receptors responsible for the mechanism of action of auxin mimics have been proposed: (1) auxin binding protein 1 (ABP1) (Tromas et al., 2010; Shi and Yang 2011); (2)auxin signaling F-box protein (TIR1/AFB); and more recently (3) S-kinase-associated protein 2 (SKP2) (Jurado et al., 2010). In addition to being found in different subcellular locations, these three auxin receptors also differ in their proposed functional roles in cell expansion, cell division, and regulation of plant development processes (Zazimalova et al., 2014).
In many cases, the selectivity of auxinic herbicides depends on the plant metabolism. Plants generally metabolize herbicides converting the original molecule into more polar products and insoluble residues (Hatzios et al., 2005). The 2,4-D metabolic pathways in sensitive and tolerant species have some similarities. Although sensitive species can sometimes metabolize 2,4-D or dicamba faster than tolerant species, the metabolites produced can be readily converted back to the original molecule. On the other hand, tolerant species usually produce non-phytotoxic and irreversible metabolites of these herbicides. The metabolites produced during the auxin metabolism in the sensitive eudicotyledons and tolerant monocotyledons are similar, but vary in the number of metabolites produced, resulting in a lower concentration of tolerant monocotyledons compared to eudicotyledons (Pillmoor and Gaunt, 1981).
Experiment 2
The toxicity evaluated at 7, 14 and 21 DAA in plants after the application of 2,4 D did not allow models adequacy in describing the behavior of intoxication of cabbage plants when the dose of herbicide was increased (Figure 3A). At 7 DAA signs of toxicity in plants was observed at the highest dose of 2,4-D (1.0 L ha-1). At 14 DAA, the toxicity was observed from the dose of 0.1 L ha-1, with values close to 10% and reaching over 60% at the highest dose. From 21 DAA, the doses above 0.2 L ha-1 caused severe symptoms of poisoning in the plant, which resulted in plant death after the application of the highest dose at 28 DAA.
[Figure omitted. Please see PDF.]
The symptoms observed in cabbage plants after the application of 2,4-D included leaf curl and folded leaf margin, followed by chlorosis and necrosis of the leaves and stems of the plants, as also observed by Santos et al. (2013).
The proposed model was not adequate to describe the evaluations of intoxication in plants caused by dicamba (Figure 3B). However, mild plant poisoning was observed only at doses of 0.2 and 1.0 L ha-1 at 14 and 21 DAA, with values close to 20%. However, in the evaluation performed at 28 DAA, no intoxication was observed, indicating that the symptoms of poisoning observed at the initial growth did not cause enough damage to be noticeable during the last evaluation of the culture.
A similarity above 80% between the productive variables was observed when the cabbage plants were submitted to 2,4-D application (Figure 4A), indicating that the application of this herbicide caused similar responses in the evaluated variables. In this case, these variables were then represented only by the number of marketable cabbages. Regarding the dicamba application, a similarity above 80% was just observed between the number and average weight of the cabbages (Figure 4B). Two groups were presented: the first corresponds to the correlated variables, represented by the number of marketable cabbages; and the other group corresponds only to the total box weight.
[Figure omitted. Please see PDF.]
The application of the doses of 2,4-D to the cabbage plants caused a reduction in the number of marketable cabbages from the 0.20 L ha-1 dose (Figure 5A). At the application of the highest dose (1.0 L ha-1), a drastic reduction in the values of the number of cabbages was observed, with an average below two marketable cabbages. No reductions were observed after the application of the dicamba doses, presenting an average of 13 marketable cabbages (Figure 5B). The most valued boxes for the current market were the ones containing 12 to 14 marketable cabbages, with an average mass of 1.4 to 2.0 kg per head.
[Figure omitted. Please see PDF.]
The use of dicamba did not cause changes in the total weight of the cabbage box at any of the doses applied to the plant. The average weight of the cabbage boxes was 27 kg per box (Figure 6).
[Figure omitted. Please see PDF.]
Similar to what was observed in the other productive variables, the average cabbage weight did not change after the application of dicamba (Figure 7). The average value of the cabbage head was 2.02 kg.
[Figure omitted. Please see PDF.]
In response to an auxinic herbicide, sensitive plants develop abnormalities such as leaf epinasty, leaf abscission, inhibition of the root growth and the aereal part of the plant (Kelley and Riechers, 2007; Grossmann, 2009). In general, the effects of auxin herbicides on the plants can be divided into three consecutive plant phases: stimulation of abnormal growth and gene expression; growth inhibition and physiological responses such as stomatal closure and finally, senescence and cell death (Grossmann, 2009). During the stimulation phase, the auxinic herbicides stimulate an increase in the production of ethylene and the biosynthesis of abscisic acid (ABA) (Hansen and Grossmann, 2000; Kraft et al., 2007; Grossmann et al., 2001). The increased levels of ABA inhibits plant growth by closing the stomata, which limits the assimilation of carbon dioxide and leads to the accumulation of hydrogen peroxide in herbicide-treated plants (second phase effects) (Kraft et al. 2007). This accumulation of reactive oxygen species is probably an important factor to the tissue damage and cell death associated with herbicide treatment (third phase effects) (Grossmann, 2009).
The plant can be tolerant to an auxinic herbicide belonging to a specific chemical group and not be tolerant to another auxinic herbicide from another chemical group (Patton et al., 2018). This was observed in the present study, since the cabbage plants (cultivar Astrus Plus) presented tolerance to dicamba doses, but were sensitive to the 2,4-D doses.
According to Jugulam et al. (2015) and Mithila and Hall (2005), there are some wild mustard (Brassica kaber) biotypes resistant to the herbicide dicamba, which is a plant belonging to the same family of cabbage. However, these authors reported that these biotypes have acquired resistance by the selection pressure, after years applying auxinic herbicides in the area. There are no studies in the literature reporting on plants with natural tolerance to auxinic herbicides in this family, as observed in this current study. It is also worth mentioining that the presence of auxin in the cabbage leaves poses a serious risk to human health (Anderson et al., 2004). Thus, further research should be performed in order to evaluate the presence of these compounds as a product of interest after its application.
Therefore, the cabbage cultivar Astrus Plus is tolerant to dicamba doses up to 1.0 L ha-1. The herbicide 2,4-D is not toxic to this cultivar under controlled conditions, but when applied in the field, it intoxicates the plants, causing a reduction in productivity, which can lead to death.
Anderson SM, Clay SA, Wrage LJ, Matthees D. Soybean foliage residues of dicamba and 2,4-D and correlation to application rates and yield. Agron J. 2004:96:750-60.
Brasil. Ministério da Agricultura, Pecuária e Abastecimento. Agrofit on Line. [acessado em: 10 de maio de 2018]. Disponível em: Disponível em:Disponível em: Disponível em:http://agrofit.agricultura.gov.br/agrofit_cons/principal_agrofit_cons .
Cavarianni RL. Densidades de plantio e doses de nitrogênio no desenvolvimento e produção de repolho [tese]. Jaboticabal: Faculdade de Ciências Agrárias e Veterinárias; 2008.
Christoffoleti PJ, Figueiredo MRA, Peres LEP, Nissen S, Todd G. Auxinic herbicides, mechanisms of action, and weed resistance: A look into recent plant science advances. Sci Agric. 2015;72:356-62.
Ferreira WR, Ranal MA, Filgueira FAR. Fertilizantes e espaçamento entre plantas na produtividade da couve da Malásia. Hortic Bras. 2002;20:635-40.
Green JM. Current state of herbicides in herbicide-resistant crops. Pest Manage Sci. 2014;70:1351-7.
Grossmann K. Auxin herbicides: current status of mechanism and mode of action. Pest Manage Sci. 2009;66:113-20.
Grossmann K, Kwiatkowski J, Tresch S. Auxin herbicides induce H2O2 overproduction and tissue damage in cleavers (Galium aparine L.). J Exp Bot. 2001;52:1811-6.
Hansen H, Grossmann K. Auxin-induced ethylene triggers abscisic acid biosynthesis and growth inhibition. Plant Physiol. 2000;124:1437-48.
Hatzios K, Hock B, Elstner E. Metabolism and elimination of toxicants. Plant Toxicol. 2005;4:469-18.
Jugulam M, Ziauddin A, So KKY, Chen S, Hall JC. Transfer of dicamba tolerance from Sinapis arvensis to Brassica napus via embryo rescue and recurrent backcross breeding. PloSone, 2015;10:141-418.
Jurado S, Abraham Z, Manzano C, Lopez-Torrejón G, Pacios LF, Del Pozo JC. The Arabidopsis cell cycle F-box protein SKP2A binds to auxin. Plant Cell. 2010;22:3891-04.
Kelley KB, Riechers DE. Recent developments in auxin biology and new opportunities for auxinic herbicide research. Pest Biochem Physiol. 2007;89:1-11.
Kraft M, Kuglitsch R, Kwiatkowski J, Frank M, Grossmann K. Indole-3-acetic acid and auxin herbicides up-regulate 9-cis-epoxycarotenoid dioxygenase gene expression and abscisic acid accumulation in cleavers (Galium aparine): interaction with ethylene. J Exp Bot. 2007;58:1497-03.
Melo PCT, Vilela NJ. Importância da cadeia produtiva brasileira de hortaliças. In: Reunião Ordinária da Câmara Setorial da Cadeia 13. Produtiva de Hortaliças/ MAPA. Brasília, DF: 2007. [acessado em: 08 de maio de 2018]. Disponível em: Disponível em: http://www.abhorticultura.com.br/downloads/cadeia_produtiva.pdf .
Mithila J, Hall JC. Comparison of ABP1 over-expressing Arabidopsis and under-expressing tobacco with an auxinic herbicide-resistant wild mustard (Brassica kaber) biotype. Plant Sci. 2005;169:21-8.
Patton AJ, Weisenberger DV, Schortgen GP. 2,4-D-Resistant Buckhorn Plantain (Plantago lanceolata) in Managed Turf. Weed Technol. 2018;32:182-9.
Pazminõ DM, Romero-Puertas MC, Sandalio LM. Insights into the toxicity mechanism of and cell response to the herbicide 2,4-D in plants. Plant Sign Behav. 2012;7:425-7.
Reis MR, Melo CAD, Raposo TP, Aquino RFBA, Aquino LA. Selectivity of herbicides to cabbage (Brassica oleracea var. capitata). Planta Daninha, 2017;35:1-6.
Seefeldt SS, Jensen JE, Fuerst P. Loglogistic analysis of herbicide dose response relationships. Weed Technol. 1995;9(2):218-27.
Moreira MA, Vidigal SM, Sediyama MAN, Santos MR. Crescimento e produção de repolho em função de doses de nitrogênio. Hortic Bras. 2011;29:117-21.
Tan X, Calderon-Villalobos LI, Sharon M, Zheng C, Robinson CV, Estelle M, Zheng N. Mechanism of auxin perception by the TIR1 ubiquitin ligase. Nature. 2007;5:640-5.
Pillmoor JB, Gaunt JK. The behaviour and mode of action of the phenoxyacetic acids in plants. In: Hutson DH, Roberts TR, editors. Progress in pesticide biochemistry. Chichester: Wiley; 1981. p.147-218.
Powles SB, Yu Q. Evolution in action: Plants resistant to herbicides. Ann Rev Plant Biol. 2010;61:317-47.
Santos DP, Braga RR, Guimarães FAR, Passos ABRJ, Silva DV, Santos JB, et al. Determinação de espécies bioindicadoras de resíduos de herbicidas auxínicos. Rev Ceres. 2013;60:354-62.
Shi JH, Yang ZB. Is ABP1 an auxin receptor yet? Molec Plant. 2011;4:635-40.
Silva GS, Cecílio Filho AB, Barbosa JC, Alves AU. Espaçamentos entrelinhas e entre plantas no crescimento e na produção de repolho roxo. Bragantia. 2011;70:538-43.
Sociedade Brasileira da Ciência das Plantas Daninhas - SBCPD. Procedimentos para instalação, avaliação e análise de experimentos com herbicidas. Londrina: SBCPD; 1995. 42p.
Tromas A, Paponov I, Perrot-Rechenmann C. Auxin binding protein 1: functional and evolutionary aspects. Trends Plant Sci.2010;15:436-46.
Zazimalova E, Petrasek J, Benkova E. Auxin and its role in plant development. Heidelberg, Germany: Springer-Verlag; 2014.
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Abstract
Farmers report many difficulties in weed management for the cultivation of this species, mainly due to slow crop growth (Moreira et al., 2011), and planting spacing (Cavarianni, 2008; Silva et al., 2011), which favours weed growth, in addition to the small number of herbicides registered (Agrofit, 2018). In literature, there are few studies on the selectivity of herbicides for cabbage cultivation, and no studies reporting the use of herbicides in controlling broadleaf weed. [...]this research aimed to evaluate the tolerance of the cabbage cultivar Astrus Plus to the herbicides 2,4-D and dicamba. The application of the doses was performed using a CO2 pressurized sprayer equipped with a hydraulic double-ended spray bar from a single fan jet, model API-11002, operating at a pressure of 3 kgf cm-2, positioned at 50 cm in plant height, when the cabbage plants had two pairs of true leaves. The evaluation of the plant poisoning at 7, 14, 21 and 28 days after the herbicide application was performed according to the grading scale proposed by the Brazilian Society of Weed Science (SBCPD, 1995), where 0% corresponds to injury absence and 100% plant death.
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Neither ProQuest nor its licensors make any representations or warranties with respect to the translations. The translations are automatically generated "AS IS" and "AS AVAILABLE" and are not retained in our systems. PROQUEST AND ITS LICENSORS SPECIFICALLY DISCLAIM ANY AND ALL EXPRESS OR IMPLIED WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES FOR AVAILABILITY, ACCURACY, TIMELINESS, COMPLETENESS, NON-INFRINGMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Your use of the translations is subject to all use restrictions contained in your Electronic Products License Agreement and by using the translation functionality you agree to forgo any and all claims against ProQuest or its licensors for your use of the translation functionality and any output derived there from. Hide full disclaimer