Crop succession and its reflections on soybean performance

The fluctuations in yield and consequently in production occurred due to climatic adversities in the main producing states of Brazil. Farming has changed over time, and past scenarios have shown high exploitation of natural resources focusing on soil tillage and conventional seeding methods. This study aimed to determine the yield performance of soybean grown under 10 consolidated crop succession systems. The experiment was conducted during the 2018/2019 crop season, before the research project entitled "Sustainable production systems with better use of biological and natural resources, with treatments arranged in a randomized block design and four replications". The treatments consisted of the following predecessor crops: Avena sativa, Avena strigosa, Triticum aestivum, Secale cereale, Brassica napus, Raphanus sativus, Avena strigosa + Raphanus sativus + Vicia sativa, Fallow, Avena strigosa + Lolium multiflorum, and Triticum aestivum ­ Fodder. Soybean was subsequently sown across winter crops. The succession that showed superior yield was Avena strigosa + Lolium multiflorum. This attribute was established by associating taller plants with the maximization of the number of grains per pod, hundred-grain mass, grain mass, and plant dry mass; in contrast, there was a lower emphasis on plant residue. The determining attributes for soybean yield were plant stand, plant height, the number of pods per plant, and total grain mass, with contrasts among groups composed of the succession of Avena sativa, Avena strigosa, Triticum aestivum, Secale cereale, and Brassica napus, distanced from Raphanus sativus, Avena strigosa + Raphanus sativus + Vicia sativa, Fallow, Avena strigosa + Lolium multiflorum, and Triticum aestivum - Fodder.

Contribution of nitrogen derived from mineral supplementation for soybean seedlings / Contribuição do nitrogênio derivado da suplementação mineral em sementes para plântulas de soja

ABSTRACT Seeds can absorb N from mineral supplementation, thus stimulating seedling development in soybeans (Glycine max (L.) Merrill). This study aimed to evaluate the contribution to soybean seedlings of N derived from mineral supplementation in seeds with different nutritional contents. Seeds of the cultivar BMX Potência RR received mineral supplementation enriched with 2.5% excess 15N. The treatments were performed in seeds in two lots, one with high and one with low nutritional content. At 2, 6 and 10 days after sowing on paper towels, the seedlings were collected and separated into cotyledons, roots and shoots. Dry matter production, root length and root volume were assessed. Total N and 15N values were analyzed in the seedling organ tissues. The seeds from the lot with lower nutritional content absorbed more N from the mineral supplement, which was accumulated in the cotyledons and redistributed to the root systems and cotyledons. At 10 days after sowing, most of the N in the organs of soybean seedlings was derived from the seed reserves, regardless of nutritional content. Thus, application of N through mineral supplementation is of low importance for the development and nutrition of seedlings.

RESUMO Sementes podem absorver N de suplementos minerais, estimulando o desenvolvimento de plântulas. O estudo objetivou avaliar a contribuição de N derivado da suplementação mineral em sementes com diferentes teores nutricionais, para plântulas de soja. Sementes de dois lotes da cultivar BMX Potência RR, contrastantes quanto ao teor nutricional, foram submetidas a aplicação de suplemento mineral enriquecido com 2,5% átomos de 15N em excesso. Aos 2, 6 e 10 dias após a semeadura em papel toalha, plântulas foram coletadas, separadas em cotilédones, sistema radicular e parte aérea. A produção de matéria seca, o comprimento e volume do sistema radicular foram avaliados. No tecido dos órgãos das plântulas foram analisados os totais de N e 15N. As sementes derivadas do lote com menor teor nutricional absorveram mais N do suplemento mineral, que foi acumulado nos cotilédones e redistribuído para o sistema radicular e parte aérea. A maior parte do N na soja ao longo de 10 dias após a semeadura é derivada das reservas da semente independentemente do teor nutricional inicial. A aplicação de N via suplementação mineral é de pouca importância para o crescimento e desenvolvimento de plântulas.

Desempenho de plântulas e produtividade de soja submetida a diferentes tratamentos químicos nas sementes / Seedlings performance and yield of soybean submitted to different chemical treatment in seeds

O tratamento químico de sementes é uma importante ferramenta para o bom estabelecimento da soja no campo. Objetivou-se nesse trabalho avaliar o efeito do tratamento com fungicida, inseticida, micronutriente e polímero na qualidade fisiológica e sanitária de sementes de soja e na produção de grãos. Foram utilizadas sementes de três cultivares NA 4823RG, BMX TurboRR e Fundacep 62RR. As sementes foram submetidas aos seguintes tratamentos: T1: sem tratamento químico; T2: fungicida, inseticida e micronutriente e T3: fungicida, inseticida, micronutriente e polímero. Os testes realizados para avaliação da qualidade fisiológica em laboratório foram germinação, comprimento de plântulas, massa seca de plântulas e teste de sanidade. Para avaliação do desempenho das sementes em campo foram observados o estabelecimento do estande inicial (aos 14 e 21 dias), massa de 100 grãos, número de grãos por legume e produção de grãos. O tratamento químico de sementes de soja não apresentou efeito fitotóxico à qualidade fisiológica das sementes em laboratório e foi eficiente no controle de patógenos associados às sementes. No desempenho a campo, o tratamento químico promove o melhor estabelecimento do estande, mas sem efeito significativo na produtividade.

Chemical treatment of seeds is an important tool for the proper establishment of the soybean crop in the field. The aim of this study was to evaluate the effect of chemical treatment with fungicide, insecticide, micronutrient and polymer in the physiological and health quality of soybean seeds, and in the yield. Three cultivars NA 4823 RG, BMX TurboRR e Fundacep 62 RR were used in this study. Different seed treatments were performed: T1: no chemical treatment (witness), T2: fungicide, insecticide and micronutrient and T3: fungicide, insecticide, micronutrient and polymer. Seed quality in laboratory was evaluated by germination, seedling length, seedling dry weight and sanity test. To determine the seeds performance in the field, were evaluated the initial stand establishment (at 14 and 21 days), weight of 100 grains, number of grains per pod and grain production. Results obtained in laboratory showed that there is no phytotoxic effect of chemical treatment in the soybean seeds and and was effective in the control of pathogens associated with seeds. In the field performance, chemical treatment of soybean seeds promoted better plant stand establishment, but without significant effect on yield.