Revista Brasileira De Herbicidas 2019; 18(2): 1-6

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Watermelon sensitivity to residual of pre-emergent herbicide applied in soybean crop

DOI: 10.7824/rbh.v18i2.669

The long-lasting residual effect of herbicides depends on the soil and molecule characteristics; however, the bioactivity of the herbicide can cause damage to the crop in rotation/succession. The most common way to identify the presence of herbicides in the soil is by the implantation of bioassays that uses a susceptible species to herbicidal molecules as an indicator of residues. The aim was to identify the sensitivity of watermelon as bioindicator to the pre-emergence herbicide residue used in soybean cultivation. The assay was carried out in a greenhouse, in 3 L pots, in a randomized block design, with four replicates, in a factorial scheme of 3×4+1, where factor A was the herbicides diclosulam, [imazapyr + imazapic], and metribuzin, and factor B the doses of commercial products [1/8D, 1/4D, 1/2D and D (recommended label dose)] plus control treatment. Four watermelon seeds were sown in soil per pot after herbicide application. The variables were analyzed 30 days after the emergence of the plants: shoot length (cm), length (cm), root volume (mL), shoot dry mass (g) and root dry mass (g). Watermelon seeds did not germinate in the treatments with sub-doses of the herbicides diclosulam and metribuzin, and the growth was reduced in the sub-doses of the herbicide [imazapyr + imazapic], showing the sensitivity of this species. The herbicides studied adequately exerted control in watermelon bioindicator plants. Watermelon has sensitivity to the herbicides diclosulam, metribuzin and the commercial mixture of the herbicides [imazapyr + imazapic], with the potential to indicate the residue of these herbicides in clayey soil.