Weed Phytosociological and Floristic Survey in Agricultural Areas of Southwestern Goiás Region

• Published in: Advances in Weed Science 2016-03, Vol.34 (1), p.65-80
• Main Authors: Santos, W F, SO, PROCÓPIO, Silva, A G, Fernandes, M F, BARROSO ALL
• Format: Article
• Language: English
• Subjects: Biomass; Corn; Cropping systems; Cultivation; Desiccation; Drying; floristic; Genetic modification; Glycine; Harvest; Herbicides; importance value; late harvest; Millet; phytosociology; PLANT SCIENCES; Sampling; Sorghum; soybean; Soybeans; Species composition; Studies; Weed control; Weeds
• ISSN: 0100-8358; 1806-9681; 0100-8358; 2675-9462
• DOI: 10.1590/S0100-83582016340100007

The use of the Roundup Ready(r) technology and the cultivation of a second crop influence the floristic composition of weed communities in Brazilian Central-West region cropping systems. This study has aimed to diagnose the dominant weed species in southwestern Goiás in areas of genetically-modified and conventional soybeans, using phytosociological and floristic surveys. Weed sampling was obtained by collecting all the plants present within a 0.5 m hollow frame, randomly thrown 20 times in each of thirty-five agricultural areas in the 2012/2013 harvest. Field survey was carried out in three periods: before desiccation for soybean sowing, before postemergence herbicide in soybean first application and before postemergence herbicide application in late harvest. A total of 525 m2 was inventoried and 3,219 weeds were collected, which included 79 species, 58 genera and 28 families. Families Poaceae, Asteraceae, Euphorbiaceae, Fabaceae, Amaranthaceae, were the most representative in the survey. Species Cenchrus echinatus, Glycine max, Chamaesyce hirta, Commelina benghalensis, and Alternanthera tenella stood out in importance. The RR+millet soybean treatment had the highest number of species (44), while the conventional soybean + sorghum treatment had the lowest number of species (18). The highest number of species was recorded in first sampling period. Treatments conventional soybean + maize and conventional soybean + millet showed higher similarity (70%), while treatments RR soybean + millet and conventional soybean + sorghum showed the least (51%). Species of difficult control were recorded in all cultivation systems analyzed. A utilização da tecnologia Roundup Ready(r) e o cultivo de segunda safra influenciam a composição florística das comunidades infestantes dos sistemas de cultivo do Centro-Oeste. Este estudo objetivou diagnosticar as espécies de plantas daninhas predominantes na região sudoeste de Goiás, em áreas de soja geneticamente modificada e soja convencional, por meio de levantamento fitossociológico e florístico. Para amostragem das plantas daninhas foi utilizado um quadrado vazado de 0,5 m, lançado aleatoriamente 20 vezes em cada uma das 35 áreas agrícolas na safra 2012/2013. O levantamento de campo foi realizado em três épocas: antes da dessecação para o plantio da soja, previamente à primeira aplicação de herbicida em pós-emergência da soja e anteriormente à aplicação de pós-emergência da safrinha. Foram inventariados 525 m2 no total, sendo co