Sistemas de implantação, irrigação e alterações fisiológicas de plantas de soja sob cultivo em terras baixas

• Ano de defesa: 2017
• Autor(a) principal: Cassol, Guilherme Vestena
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Santa Maria; Brasil; Agronomia; UFSM; Programa de Pós-Graduação em Agronomia; Centro de Ciências Rurais
• Palavras-chave em Português: Glycine max (L.) Merrill; Sistemas de implantação; Estresse hídrico; Fixação biológica de nitrogênio; Rotação de culturas; Planting systems; Water stress; Biological nitrogen fixation; Crop rotation; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA
• Link de acesso: http://repositorio.ufsm.br/handle/1/11644

Soybean has been the main crop used in rotation with irrigated rice in Rio Grande do Sul. However, soybean cultivation in lowland represents a high-risk activity due to stresses that generally occur in this environment. These stresses may significantly reduce growth and development of soybean plants by limiting important physiological processes such as photosynthesis and biological nitrogen fixation. In view of the above, the thesis work aimed to determine the influence of different cropping and irrigation systems on root growth, nodulation, oxidative stress, photosynthesis, soil water holding capacity, water use efficiency and grain yield of soybean in lowlands. Two experiments were carried out under field conditions and one under greenhouse conditions in the Várzea Experimental area of the Federal University of Santa Maria, RS, during 2014/15 and 2015/16 growing seasons. For the burndown timing of ryegrass experiment, applications were carried out between 20 and 90 days before soybean planting on raised seedbeds. The experiment 1 involving cropping systems and irrigation consisted of combinations between raised seedbeds flat planting with or without the practice of irrigation. The experiment 2, was carried out under greenhouse condictions and was characterized by the implementation of 10 days water deficit during V6 (six expanded trifoliate), R2 (full flowering) and R5 (grain filling) growth stages. Based on the main results, it was observed that desiccation and sowing intervals of soybean less than 60 days or quantities of ryegrass straw remaining on the soil surface higher than 1000 kg ha-1 significantly increase soil moisture retention at the sowing time. Growing soybeans using raised seedbeds increase crop yield and reduce irrigation water use when compared to flat-planting of soybean in a rice-soybean rotation. Water shortage during the grain filling period significantly reduces grain yield of soybean in lowlands.