Suscetibilidade da aveia-preta ao residual de imazethapyr no solo

Abstract

The cool seanson pastures is one of the alternatives for succession with irrigated rice cultivation, with black oats (Avena strigosa Schereb.) being quite common. However, in rice crops predominates the use of cultivars tolerant to imidazolinone chemical group herbicides, which may present residual in the soil for two years. The aim of this research was to evaluate the susceptibility of black oat to the residual of imazethapyr herbicide in the soil. The research was carried out in an experimental area, from Federal University of Pampa (Campus Itaqui), in Haplic Plinthosol. The experimental was conducted in a randomized complete block design, with four replications. The imazethapyr application occurred on 14/05/16 at doses of: 0; 26.5; 53; 106; 212 and 424 g a.i. ha-¹, corresponding to 0, ¼; ½; 1, 2 and 4x, x = recommended dose for rice cultivation. The black oat sowing, cultivar Embrapa BRS 139 occurred one month after application, using 150 plants m-². The Evaluation was performed at 14, 21, 28, 35, 42, 49 and 56 days after emergence (DAE), plant height (cm) and herbicide symptom. In the medium milky growth stage, the shoot was cut and shoot dry matter (MSPA) was determined. Data were submitted to analysis of variance (p≤0.05). When significant difference was detected, regression analysis was performed using nonlinear models. The results show that black oat is susceptible to the residual of imazethapyr in the soil, applied 30 days before sowing, and may prevent succession in areas where rice with herbicide technology based on imidazolinones is used.