José Maria Arcanjo Alves

Resposta do feijão-caupi à doses e formas de aplicação de fósforo em Latossolo Amarelo do Estado de Roraima

Phosphorus fertilization and ways of phosphate fertilizers application are important factors considering crop management. This study aimed at assessing the effect of phosphorus rates and phosphate fertilizers application forms on growth and phosphorus uptake of cowpea plants cropped on cerrado soil in the State of Roraima, Brazil. An experiment took place under field conditions, on a Yellow Latosol, at Cauame Campus of Roraimas Federal University, located in the municipality of Boa Vista/RR. The experimental design was split-plot, in a completely randomized blocks, with three replicates. The plots consisted of the following phosphoric fertilizers application forms: a) broadcasting; b) single furrow and c) double furrow. Sub-plots corresponded to phosphorus doses: 0, 0,5; 1,0; 1,5, and 2,0 times the recommended dose for cowpea maintenance fertilization (60 kg ha-1 of P2O5). There was a significant effect of P rates over plant growth and plant uptake. Application of fertilizer in double furrows promoted higher plant growth, grain yield, and plant phosphorous uptake.

Qualidade de sementes de soja BRS Tracajá, colhidas em Roraima em função do tamanho no armazenamento

The main goal of this study was to evaluate the physical and physiological quality of soybean seeds, cultivar BRS Tracaja, harvested in savanna (cerrado) area of the State of Roraima according to size and storage. The seeds were cleaned and manually classified by size, using three sieves with round holes with dimensions: 5.5; 6.0 and 6.5 mm, subsequently disposed in proper paper bags and stored during six months under conditions of temperature (23 °C) and air relative humidity (60%) at Embrapa Roraimas seed laboratory. The seed quality was evaluated in the beginning of storage and after 2; 4 and 6 months of storage according to the thousand seeds weight test, germination, first germination count, electrical conductivity, field seedling emergence, speed of seedling emergence in the field, seedling dry weight and dry weight per seedling. The results show that the size influences physical and physiological quality of seeds from cultivar BRS Tracaja during storage. Seeds of higher sizes from cultivar Tracaja (6.5 mm) present higher value in the thousand seeds weight test. The highest percentages of germination and vigor through seeds electrical conductivity test, concerning seeds of BRS Tracaja cultivar, during storage, were obtained among seeds of larger sizes (6.0 and 6.5 mm). Seeds with larger sizes from BRS Tracaja (6.0 and 6.5 mm) showed during storage, the highest percentage of field seedling emergence and the seeds with smaller sizes (5.5 mm), the smallest rates of field speed of seedling emergence.

Caracterização de plantas daninhas em área rotacionada de milho e feijão-caupi em plantio direto

The aim of this work was to characterize weeds in a rotational area of maize and cowpea under notillage system. The samples were collected four months after the corn harvest. For sampling, 0.50 • 0.50 m cast iron square, randomly cast twenty-five times in the experimental area with 1508 m was used. The weeds were identified and quantified by means of the sum of the samples obtained by the launch of the square. The evaluated variables included: frequency, density, abundance, relative frequency, relative density, relative abundance and importance value index of the species. The botanical classes, families, species, type of propagation, life cycle and habit of growth were described. In the experimental area, 38 species were identified, distributed in 7 families, most of them (68.4%) the botanical class of dicotyledons. The families Fabaceae (28.9%) and Poaceae (26.3%) predominated. The species that presented the highest value of importance were: Digitaria horizontalis with 44.66% preceded by Cyperus flavus with 34.13%, Digitaria insulares with 22.87%, Cyperus sp. with 16.18% and Brachiaria plantaginea with IVR of 14.75%, which are of the same order of magnitude and should also be considered in the management strategy.

Physiological quality of cowpea seeds for different periods of storage

The aim of this study was to evaluate physiological quality in the seeds of four cowpea cultivars during nine months of storage. The cowpea cultivars used were BRS Mazagao, UFRR Grao Verde, Pretinho Precoce 1 and BRS Guariba, produced intercropped with cassava in the experimental area of the Centre for Agrarian Science of the Federal University of Roraima, in Boa Vista. After harvest, the seeds were dried, hand cleaned, placed in PET bottles and stored for nine months at a temperature of 23 oC and a relative humidity of 60% at the Seed Analysis Laboratory of Embrapa Roraima. Data analysis was carried out in a completely randomised design, in a 4 x 4 factorial scheme with eight replications. The physiological quality of the seeds was evaluated at the start of storage, and after 3, 6 and 9 months, for germination, first germination count, 1000-seed weight, moisture, electrical conductivity, speed of emergence, seedling field emergence and water gain. Physiological quality in the seeds of BRS Guariba is influenced by the storage period. Irrespective of storage period, seeds of the Mazagao cultivar show superior physiological quality in relation to the other cultivars. Seeds of the BRS Guariba and Grao Verde cultivars show a reduction in physiological quality after three months of storage.

Morphophysiology of Germination among Seeds of Pau-rainha (Centrolobium paraense) Collected in the State of Roraima

This work intended to characterize the seed morphology, water absorption patterns and to determine the vigor among different colored seeds of the species Centrolobium paraense (Fabaceae). For this purpose, samaras which were opened were collected from two sites—Água Boa (AB) and Taiano (TAI) located in the state of Roraima, and the seeds screened by the coat coloration (light brown/intermediate brown/dark brown) for four conditions (two sites and two years of collection). Evaluation of water absorption by the seeds at different periods, mass of 1,000 seeds, water content, electrical conductivity (EC), seedling emergence and emergence velocity (EV) were performed. The water absorption by the seeds of Centrolobium paraense indicates coat permeability to water and distinct absorptions according to coat colorations. The EC test is efficient in determining the physiological quality of seeds of Centrolobium paraense. Seed coat coloration affects the physiological quality of the seeds of Centrolobium paraense. It is possible to distinguish the seeds of AB and TAI into two degrees of physiological quality, the light brown-colored seeds being more vigorous.

Avaliação da fixação biológica de nitrogênio em feijão-caupi submetido a diferentes manejos da vegetação natural na savana de Roraima.

Objetivou-se com este trabalho avaliar a fixacao biologica de nitrogenio em feijao-caupi submetido a diferentes manejos da vegetacao natural, com e sem adubacao orgânica com esterco bovino, da savana de Roraima. O experimento foi instalado na area experimental do CCA/UFRR, em Boa Vista, Roraima. O plantio das sementes de feijao-caupi, cultivar BRS Arace, inoculadas com Bradyrhizobium BR 3262, foi realizado em julho de 2011 e os tratamentos foram dispostos em um delineamento experimental de blocos ao acaso em esquema fatorial (3 x 2) com quatro repeticoes. O primeiro fator correspondeu ao manejo da vegetacao natural: com aplicacao de glifosato, com corte da vegetacao natural e sem corte da vegetacao natural. O segundo fator correspondeu a aplicacao de esterco bovino: com e sem aplicacao. Aos 35 dias apos o plantio foi efetuada a coleta das plantas de feijao-caupi para mensurar o numero de nodulos; massa fresca e seca dos nodulos; altura da planta; numero de folhas, massa fresca e seca da parte aerea; massa fresca e seca da raiz. A aplicacao a lanco de esterco bovino na quantidade de 2,0 L m-2 sobre a vegetacao natural da savana de Roraima favorece o aumento do numero de nodulos por planta de feijao-caupi. O manejo da vegetacao natural com o uso do glifosato, independentemente do uso do esterco, favorece a nodulacao das raizes e contribui com o maior crescimento e desenvolvimento da planta de feijao-caupi.

Ácido cianídrico em tecidos de mandioca em função da idade da planta e adubação nitrogenada

O objetivo deste trabalho foi avaliar o teor de acido cianidrico em tecidos de mandioca, em funcao da idade da planta e niveis de adubacao nitrogenada. Utilizou-se o delineamento experimental de blocos ao acaso, em arranjo de parcelas subdivididas, com quatro repeticoes. As doses de nitrogenio em cobertura (0, 30, 60, 150 e 330 kg ha -1 ) foram alocadas nas parcelas, e as epocas de avaliacao (90, 120, 150, 180, 240, 300 e 360 dias apos o plantio), nas subparcelas. Os teores de acido cianidrico foram avaliados em tecidos da folha, caule, polpa e cortex da raiz da cultivar Aciolina. Os efeitos das doses de N e das epocas de avaliacao foram independentes. Doses entre 219 e 241 kg ha -1 de N em cobertura proporcionam os maiores teores de acido cianidrico, que variaram de 332 a 401 mg kg -1 de materia fresca nos tecidos avaliados. O teor de acido cianidrico nos tecidos reduz-se linearmente com a idade da planta. O cortex da raiz acumula o maior teor de acido cianidrico, e a polpa da raiz o menor. Por ocasiao da colheita, aos 360 dias apos o plantio, essa cultivare classificada como mandioca mansa.

CARACTERÍSTICAS AGRO-BOTÂNICAS DE RAÍZES DE MANDIOCA EM FILEIRAS SIMPLES E DUPLAS CONSORCIADA COM FEIJÃO COMUM

Objetivou-se com este trabalho avaliar caracteristicas agro-botânicas de raizes demandioca em fileiras simples e duplas consorciadas com feijao comum. O experimento foi realizadoem Coimbra-MG, no campo experimental do Departamento de Fitotecnia da Universidade Federal deVicosa. O delineamento experimental adotado foi em blocos casualizados, com seis tratamentos equatro repeticoes. Os tratamentos foram: fileira simples de mandioca em monocultivo, fileira simplesde mandioca mais uma linha de feijao, fileira dupla de mandioca em monocultivo, fileira dupla demandioca mais uma linha de feijao, fileira dupla de mandioca mais duas linhas de feijao e fileira duplade mandioca mais tres linhas de feijao As parcelas consistiram de 6,0 m de comprimento por 6,0 mde largura, com area util de 8,0 m2 para os tratamentos de fileiras simples de mandioca emmonocultivo e com feijao, enquanto a area util de 10 m2 para os tratamentos com fileiras duplas. Asraizes de mandioca foram colhidas aos 15 meses e foram avaliadas as caracteristicas: produtividadede raizes, numero de raizes por planta, comprimento de raiz, diâmetro de raiz, materia seca de raiz.Os resultados permitiram concluir que: 1) e possivel cultivar mandioca consorciada com feijaocomum, tanto em fileiras simples quanto em fileiras duplas, sem maiores prejuizos para o rendimentode raizes de mandioca; 2) o monocultivo em fileira simples de mandioca apresentou os maiorescomprimentos de raizes, entretanto obtiveram o menor diâmetro.