Produção de Minimelancia em Sistema Orgânico no Sul do Rio Grande do Sul como Alternativa para a Diversificação das Áreas de Tabaco.

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Determination of βS haplotypes in patients with sickle-cell anemia in the state of Rio Grande do Norte, Brazil

βS haplotypes were studied in 47 non-related patients with sickle-cell anemia from the state of Rio Grande do Norte, Brazil. Molecular analysis was conducted by PCR/RFLP using restriction endonucleases XmnI, HindIII, HincII and HinfI to analyze six polymorphic sites from the beta cluster. Twenty-seven patients (57.5%) were identified with genotype CAR/CAR, 9 (19.1%) CAR/BEN, 6 (12.8%) CAR/CAM, 1 (2.1%) BEN/BEN, 2 (4.3%) CAR/Atp, 1 (2.1%) BEN/Atp and 1 (2.1%) with genotype Atp/Atp. The greater frequency of Cameroon haplotypes compared to other Brazilian states suggests the existence of a peculiarity of African origin in the state of Rio Grande do Norte

Quantificação do banco de sementes de plantas daninhas sob diferentes sistemas de manejo do solo.

A composição, dinâmica e longevidade do banco de sementes do solo é variável em função do sistema de manejo, condições climáticas e espécies de plantas daninhas presentes. Desse modo, objetivou-se quantificar o banco de sementes de plantas daninhas do solo sob diferentes sistemas de manejo do solo. O experimento foi realizado em área de cerrado, no campo experimental da Embrapa e posteriormente em casa de vegetação da Universidade Federal de Roraima, Boa Vista, Roraima, Brasil. Foi utilizado delineamento inteiramente casualizado em esquema fatorial 5x4x2 com quatro repetições. Os tratamentos consistiram do uso associado entre cinco diferentes sistemas de manejo do solo (vegetação nativa, cultivo mínimo, sistema de plantio direto, sistema convencional e sistema convencional com rotação de cultura), quatro profundidades de solo (0-5; 5-10; 10-15 e 15-20 cm) e duas amostras de solo (indeformada e deformada). O sistema de plantio direto mostra-se eficiente no controle de plantas daninhas, pois o número de germinantes é inferior ao observado no sistema convencional, convencional com rotação e vegetação nativa. O maior número de germinantes são encontradas nas amostras deformadas e nas profundidades 0-5 e 5-10 cm do solo. Palavras-chaves: sistemas de cultivo; cerrado de Roraima; plantas infestantes

Occurrence of noxious weeds under different soil management systems.

The aim of this work was to identify weed species in areas under different soil management systems. The research was carried out in the Brazilian Agricultural Research Corporation experimental area, in the 2017/2018 harvest, in the city of Boa Vista, Roraima State, Brazil. The experimental design was randomized blocks and the treatments included of five soil management systems (native vegetation, minimum tillage, no-tillage, conventional tillage and conventional tillage with crop rotation). Weed collection, identification, counting and drying were performed and then the phytosociological indices (Relative density, relative frequency, relative abundance, importance value index, relative importance value index and dry mass) were calculated. Variance analysis with means compared by Tukey test (P <0.05), group analysis by hierarchical and non-hierarchical method, and principal component analysis were performed. Correlation coefficients of the variables were estimated. No and minimum tillage systems had the lowest weed rates per square meter. The botanical families Poaceae, Fabaceae and Rubiaceae are the most representative in the studied systems. Concerning relative frequency, the species Cyperus flavus stood out in all treatments other than native vegetation