Weed phytosociology in diversified soybean production systems

Abstract

The knowledge of the impacts of the management practices used in each agricultural production system on the ecological interactions between commercial crops and weed populations can assist in the development of specific and sustainable integrated management strategies. This study aimed to assess weed communities in soybean in succession to second-crop corn and production systems with crop diversification in Northern Paraná State. The study was conducted during three agricultural years (2014/2017). Six treatments were setup: 1 – corn/soybean, corn/soybean, and corn/soybean), 2 – white oat/soybean, rye/corn, and wheat/soybean, 3 – oat + rye/soybean, oat + radish/corn, and congo grass/soybean, 4 – canola/corn, crambe/corn, and safflower/soybean, 5 – buckwheat/ radish/corn, bean/soybean, and buckwheat/oat/soybean, and 6 – wheat/corn + congo grass, canola/corn, and bean/soybean. The relative importance value index of each weed species and the soil cover (soil, straw, and weeds) were assessed. The experimental design consisted of randomized blocks with four replications of 300 m2 (20 × 15 m). The production systems white oat/soybean, rye/corn, and wheat/soybean; buckwheat/radish/corn, bean/soybean, buckwheat/oat/soybean; and wheat/corn+congo grass, canola/corn, bean/soybean had a suppressive effect on the species Commelina benghalensis. Euphorbia heterophylla and Digitaria horizontalis were the species most adapted to the assessed production systems. Seeds remaining from crambe and radish cultivations became volunteer plants in subsequent cultivations.