O herbicida 2,4-D é utilizado principalmente para o controle de plantas daninhas em condições de pós-emergência em culturas em que o herbicida é seletivo, bem como no manejo da vegetação em pré-plantio; no entanto, devido a suas características físico-químicas, pode ocasionar danos às culturas vizinhas sensíveis, através dos fenômenos de deriva da molécula durante as pulverizações. Sendo assim, é de fundamental importância o conhecimento técnico dos impactos causados pela deriva do herbicida 2,4-D em culturas sensíveis. No entanto, as informações existentes na literatura para dar suporte às possíveis liberações futuras de culturas resistentes a este herbicida são escassas. Os experimentos foram conduzidos em casa-de-vegetação e laboratório da Escola Superior de Agricultura \"Luiz de Queiroz\" - Universidade de São Paulo - ESALQ/USP. Os objetivos da presente pesquisa foram: (i) avaliar a influência do herbicida 2,4-D no desenvolvimento das culturas do algodão e soja em, diferentes estádios fenológicos, (ii) avaliar os possíveis danos causados pela deriva do herbicida 2,4-D no crescimento e desenvolvimento das culturas de algodão e soja, em diferentes estádios fenológicos, e (iii) observar através da microscopia eletrônica de varredura possíveis alterações nas estruturas foliares das plantas de algodão e soja após o contato com o herbicida. Curvas de doseresposta foram obtidas a partir de experimentos conduzidos em casa-de-vegetação. Para isso, foram conduzidos dois ensaios, sendo os tratamentos com o herbicida aplicado quando as plantas atingiram os estágios fenológicos: V2 (segundo nó vegetativo); R1 (início da floração para a cultura de soja), F1 (início da floração da cultura de algodão); e R6 (vagens da soja com enchimento pleno e folhas verdes) e C1 (algodão no final do florescimento efetivo e frutificação plena). No primeiro experimento os tratamentos utilizados foram: 0D (testemunha), 0,25D, 0,5D, 1D, 2D e 4D, sendo D a dose recomendada do 2,4-D, e no segundo experimento as doses utilizadas foram: 0D, 1D, 0,1D, 0,01D, 0,001D, 0,0001D. Utilizando as mesmas plantas da primeira etapa da pesquisa foram feitas amostragens das folhas para a caracterização foliar através de microscopia eletrônica de varredura. O 2,4-D comprometeu significativamente o crescimento e desenvolvimento das plantas de soja em todos os estádios fenológicos, com fitotoxicidade superiores a 65%. Resultados semelhantes foram obtidos na cultura do algodão, onde o menor nível de dano foi de 42,5% relativa à aplicação do herbicida no estádio fenológico R6 na dose de 0,25D. Observando os tratamentos nas subdoses do herbicida, na soja, verificou se que a maior porcentagem de fitotoxicidade foi obtida na dose de 0,1D, em todos os estádios fenológicos, os níveis de dano foram superiores a 50% na última avaliação. Em relação à cultura do algodão resultados semelhantes foram obtidos, com exceção do estádio fenológico R6, quando todos os estádios apresentaram porcentagem de fitotoxicidade superior a 40%. Em relação às características foliares do algodão e soja após aplicações de 2,4-D através da análise das características foliares em microscópio eletrônico de varredura, após a aplicação do herbicida, observou-se que o produto promoveu alterações nas estruturas foliares de algodão e soja em todas as doses estudadas. / The herbicide 2,4-D is used to control weeds in post-emergence conditions in crops which it is selective, as well in pre-planting vegetation management, however, due to its physical-chemical characteristics it may cause damage to susceptible neighbor crops, by the drift of the molecule during the spray. Therefore, it is of fundamental importance the technical knowledge of the impacts caused by the drift of the molecule during the application. The experiments were conducted in greenhouse and in the laboratory of the College of Agriculture \"Luiz de Queiroz\". So the objectives of this study were (i) to evaluate the possible damage caused by 2,4-D in the initial development of cotton and soybean crops (ii) to evaluate the possible damage caused by 2,4-D drift in the initial development of cotton and soybean crops and (iii) to observe by electron microscopy scanning possible changes in leaf structure of plants cotton and soybeans after contact with the herbicide. Dose-response curves were obtained from experiments conducted in the greenhouse. For that, it was conducted two trials, being the treatments with the herbicide sprayed when the plants reached the following phenological stages: V2 (second vegetative node); R1 (beginning of flowering for soybeans) and F1 (beginning of flowering in cotton); and R6 (soybean pods with full filling and green leaves) and C1 (cotton at the end of effective flowering and fruiting full). In the first experiment the doses were related to the effect of doses (0D, 0.25D, 0.5D, 1D, 2D, 4D), where D is the recommended dose of the herbicide 2,4-D, and in the second experiment evaluated the effect of underdoses (0D, 1D, 0.1D, 0.01D, 0.001D and 0.0001D). Using the same plants of the first and second step of the research it was sampled leaves for the foliar characterization by scanning electron microscopy. The 2,4-D affected significantly the growth and development of the soybean plants in all phenological stages, with phytotoxicity superior to 65%. Similar results were obtained in cotton, where the lower level of damage was 42.5% on the application of the herbicide on growth stage R6 with the 0.25D dose. Regarding to the application of doses of the herbicide 2,4-D on soybeans, it was observed that the highest percentage of phytotoxicity to the crop was at the dose of 0.1D; in all growth stages the damage levels were above 50% in the last evaluation. Regarding to the cotton crop, similar results were obtained, except for the R6 growth stage, every stage showed higher percentage of phytotoxicity than 40%. Regarding to the characteristics of the cotton and soybean leaves following 2,4-D application, it was found that the product caused alterations in leaf structure of the plants in all doses.

Hohe Sojabohnenimporte und damit verbundene Umweltprobleme erfordern ein Umdenken in der Landwirtschaft, um den Bedarf an pflanzlichem Eiweiß zu decken. Die Sojabohne bietet ein hohes Potenzial, da sie bisher in geringem Umfang in Mitteleuropa angebaut wird. Zwischen 2017 bis 2019 wurden Gefäß- und Feldversuchen an verschiedenen Standorten Deutschlands und Polens durchgeführt. Die Forschungsziele waren a) die Überdauerung von Bradyrhizobium sp. im Boden mit unterschiedlicher Sojabohnenanbauhistorie zu untersuchen, b) die Auswirkungen einer Inokulation von Sojabohnen im Zwischenfruchtanbau auf die nachfolgende Sojabohnen-Hauptkultur zu testen sowie c) das Wurzelwachstum der Sojabohne und die Fähigkeit der Nährstoffaufnahme aus dem Unterboden zu beleuchten. Die DNA-Sequenzierung aus den Bodenproben zeigte, dass Bradyrhizobium sp. auch unter mitteleuropäischen Standortbedingungen persistent ist und auch nach einer siebenjährigen Anbaupause eine effektive Symbiose mit der Sojabohne eingehen kann. Durch den Zwischenfruchtanbau mit Sojabohne, konnte in der darauffolgenden Hauptkultur Sojabohne eine Erhöhung der Knöllchenanzahl an den Seitenwurzeln um 43 % sowie eine Ertragssteigerung von 15 % bei Impfung der Sojabohne im Zwischen- und Hauptfruchtbau dokumentiert werden. Sojabohnen können sowohl auf Sand-, als auch auf Lößböden bis 1,35 m tief wurzeln und erreichten im Oberboden eine Wurzellängendichte bis 2,4 cm/cm3. Außerdem wurde gezeigt, dass Sojabohnen trotz Trockenphasen 15 % des oberflächlich ausgebrachten 15N-markierten Stickstoffs, in regenreichen Jahren sogar 67 % des oberflächlich ausgebrachten Stickstoffs aufnahmen. Bis zur Blüte nahmen die Pflanzen aus einer Tiefe von 0,3 m zwischen 19 und 77 % des ausgebrachten Stickstoffs auf und aus 0,6 m Bodentiefe zwischen zwei und 64 %. Die Sojabohne war in der Lage, ihren Stickstoffbedarf aus bodenbürtigen Quellen zu decken und die Ertragsbildung in Trockenperioden durch eine Wasseraufnahme aus dem Unterboden zusichern. / High soybean imports and the associated environmental problems require a rethink in domestic agriculture in order to meet the demand for vegetable protein. Soybeans offer great potential in this context, although they have only been cultivated on a small scale in Central Europe to date compared to consumption. Between 2017 and 2019, container and field trials were conducted at various locations in Eastern Germany and Poland. The research objectives were a) investigate the persistence of Bradyrhizobium sp. in soils with different soybean cultivation histories, b) test the effects of soybean inoculation in intercropping on the subsequent soybean main crop and c) shed light on the root growth of soybeans and the ability to take up nutrients from the subsoil. The sequencing of DNA from the soil samples showed that Bradyrhizobium sp. is persistent even under Central European site conditions and can form an effective symbiosis with soybeans even after a seven-year cultivation break. In addition, intercropping with soybeans in the subsequent main crop soybeans led to a 43 % higher number of nodules on the lateral roots and to a yield increase of 15 % when the soybeans were inoculated in the intercrop and in the main crop. Soybeans can root up to 1.35 m deep on both sandy and loess soils and reach a root length density of up to 2.4 cm/cm3 in the topsoil. It was also shown that soybeans took up 15 % of the nitrogen applied to the surface in dry periods and 67 % in rainy years, between 19 and 77 % of the nitrogen applied at a soil depth of 0.3 m and between 2 and 64 % of the nitrogen applied at a soil depth of 0.6 m by the time of flowering. This means that soybeans with well-developed root systems that extend deep into the soil are able to meet their nitrogen requirements from soil-borne sources and ensure yield formation in dry periods by absorbing water from the subsoil.