Seletividade do amendoim-forrageiro (Arachis pintoi Krap. & Greg.) a herbicidas.

Abstract

This work aimed to study the tolerance of forage peanut at different herbicides in the edapho-climatic conditions of the city of Manaus-AM. The experiment was carried out at Embrapa Western Amazon, located on km 29 highway AM 010, Manaus-AM, from May to October 2009, in greenhouse conditions. The experimental design was completely randomized (5x6) with one additional treatment (control), with four replications in randomized block design (RBD). We applied six different doses of herbicides: Recommended Dose (RD), 25% DR (D1), 50% DR (D2), 75% DR (D3) and 125% DR (D4), plus additional treatment - control (D0 ). Stolons were used (20 cm) of forager peanut, cultivar Amarillo, planted in polyethylene bags containing 6.0 kg of capoeira forest humus substrate. Herbicide application was performed 70 days after planting (DAP), with a pressurized backpack sprayer at CO2. Visual assessments of tolerance (phytotoxicity) of the peanut plants (A. pintoi.) were examined in 7, 14, 21 and 28 days after herbicide application (DAA). For the evaluation of dry matter, was held the cutting of the plants at 110 days after planting (DAP) and its parts were separated in leaves, stems and roots. We removed a leaf of each plant to measure the specific leaf area (SLA). For processing the data we used SAS software, we did analyse of variance to test the differences between herbicides and the variables and regression analysis of doses of herbicides. Fomesafen treatment showed higher weight of dry matter of leaves (9.82 g plant-1) standing out from other herbicides. The A. pintoi was more tolerant to herbicides fomesafen with 6.57%of phytotoxicity, followed by bentazon (6.28%), and fluazifop-p-butyl (6.13%). The sulfentrazone showed the highest percentages of phytotoxicity (15.2%), resulting in a greater number of plants with leaf spots, necrosis and curling of leaves. The Arachis pintoi was tolerant to the herbicides fomesafen, bentazon and fluazifop-p-butyl, thus being the more suitable herbicides for the maintenance of A.pintoi