Soybeans Competitiveness with Morning Glory

• Published in: Advances in Weed Science 2016-03, Vol.34 (1), p.25-33
• Main Authors: PICCININI, F., MARTIN, T.N., MACHADO, S.L.O., KRUSE, N.D., SCHMATZ, R.
• Format: Article
• Language: English
• Subjects: Biotypes; Competition; Competitiveness; Crop yield; Flora; Glycine; Greenhouses; Herbicide resistance; I. indivisa; I. purpurea; I. triloba; Incidence; Interspecific; Leaf area; Leaves; PLANT SCIENCES; Plants (botany); replacement series; Seeds; Shoots; Soybeans; Weed control; Weeds
• ISSN: 0100-8358; 1806-9681; 0100-8358; 2675-9462
• DOI: 10.1590/S0100-83582016340100003

Weeds interfere negatively on development, yield and quality of soybeans (Glycine max). Inadequate weed control by herbicide use can select for resistant or tolerant biotypes, leading to a shift in the weed flora. An example is the increase of incidence of morning glory (Ipomoea spp.) in soybeans growing areas in South Brazil. The aim of this study was to determine the competitiveness of soybeans intercropped with I. triloba, I. indivisa and I. purpurea through a replacement experiments series. Greenhouse experiments were conducted in a completely randomized design with four replications. The first experiment was carried out aiming to get the plant population while total plant dry mass remained constant. Other experiments were done under replacement series experiments with soybeans and morning glory ratios of 100:0, 75:25, 50:50, 25:75 and 100:0 using the 250 plant m-2 defined by the preliminary experiment. Leaf area, root and shoots dry mass were assessed. Diagrams along with index interpretation were used to performed a competitiveness analysis. Soybeans showed greater competitiveness as I. triloba, I. purpurea and I. indivisa species for the leaf area, root and shoots dry mass variables. Intraspecific competition prevails between soybean plants whilst interspecific competition prevails for morning glory. As plantas daninhas interferem negativamente no desenvolvimento, na produtividade e na qualidade da soja. O controle inadequado das plantas daninhas pelo uso de herbicidas pode selecionar biótipos resistentes e/ou plantas tolerantes, provocando mudança na flora de plantas daninhas. Objetivou-se com este trabalho determinar a competitividade da soja em convivência com plantas de I. triloba, I. indivisa e I. purpurea, por meio de experimentos em série de substituição. Os experimentos foram realizados em casa de vegetação, no delineamento inteiramente casualizado com quatro repetições. O primeiro experimento foi realizado com a finalidade de obter a população de plantas a partir da qual a massa seca total das plantas permanecesse constante; já os demais experimentos foram realizados em série de substituição com proporções entre soja e corda-de-viola de 100:0, 75:25, 50:50, 25:75 e 100:0, com população definida no experimento preliminar de 250 plantas m-2. As variáveis avaliadas foram área foliar, massa de matéria seca de raiz e massa de matéria seca da parte aérea. A análise da competitividade foi feita por diagramas de competitividade e por interpretações