Efeitos da deriva simulada de 2,4-D sobre feijão, soja, tomateiro e videira

Abstract

The drift of auxinic herbicides has become a major current problem due to the great impact on sensitive species, with losses for farmers. Drift impacts are influenced by different factors and tolerance varies between cultivated species. However, there are few studies comparing the effects of simulated drift on different cultivated species. Therefore, the present study aimed to evaluate, in a comparative way, the effects caused by the application of different sub-doses of 2,4-D in four eudicotyledonous cultivated species considered sensitive to this herbicide and determine whether night applications would result in greater plant tolerance. The experiment was conducted in a greenhouse at UTFPR, Campus Pato Branco, between the end of 2019 and the beginning of 2020. The sub-doses of 2,4-D applied were 1% (4.56 g of acid equivalente [a.e.] ha-1 ), 2% (9.12 g a.e. ha-1), 4% (18.24 g a.e. ha-1), 8% (36.48ga.e. ha-1), with the addition of a check without spraying (0 g ha -1), assuming an application of 1.0 L ha-1 of commercial herbicide Enlist Colex-D® (456 g ha-1 e.a. 2.4-D). The tested crops were: dry bean, soybeans, tomato and vine. The assessments performed at 7, 14, 21 and 28 days after application (DAA) depended on the species, and included plant length, phytotoxicity, number of nodes and branches, number of pods, green and dry matter of pods / fruits and total dry matter of the plants. The data obtained were subjected to analysis of variance (ANOVA) with Tukey's test (5%) for comparison of means. It was shown that all 2,4-D sub- doses negatively affected plants, with some variables being more affected than others. In general terms, the sub-doses of the herbicide 2,4-D had a greater effect on the cultivated species than the period of application of the herbicide (day or night). Phytotoxicity was the most sensitive variable and it was high in all crops, demonstrating that the plants are sensible, even in relatively low concentrations of the herbicide 2,4-D. Height was the second most affected variable, most concentrations resulting in a negative effect. Considering the different variables and the time period in which they were evaluated, it was possible to highlight the following decreasing order of sensitivity among the cultivated species: soybean = vine > bean > tomato.