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Boa Vista, Brazil

Araujo W.F.,CCA UFRR | de Souza K.T.S.,University of Sao Paulo | Viana T.V.A.,Federal University of Ceara | Azevedo B.M.,Federal University of Ceara | Oliveira G.A.,UFRR
Revista Caatinga | Year: 2010

The purpose of this study was to evaluate the production of lettuce Lactuca sativa cv. Verônica to water levels. The experiment was conducted at Centro de Ciências Agrárias at Universidade Federal de Roraima (State of Roraima, Brazil). The experiment was carried out in a greenhouse following the completely randomized blocks design with four replications. The treatments consisted of six water levels based on fractions of the class A pan daily evapotranspiration (20%, 40%, 60%, 80%, 100% e 120%). The results of yield and fresh matter showed a linear response of the applied irrigation levels. The water use efficiency showed a decreasing linear response with respect to the irrigation levels. The maximum of yield showed 17.35 t ha -1 with 120% Class A Pan evaporation level. Source

Ivanoff M.E.A.,Federal University of Roraima | Uchoa S.C.P.,CCA UFRR | Alves J.M.A.,BR 174 | Smiderle O.J.,Embrapa Roraima | Sediyama T.,Campus Universitario
Revista Ciencia Agronomica | Year: 2010

Nitrogen is the nutrient that limits most the production in the culture of sunflower (Helianthus annuus L). The nutritional requirements among cultivars of the same species is distinct, under the same conditions of culture and for the same agricultural year. With the objective of evaluating four different ways of nitrogen application in the production components of different genotypes of sunflower, an experiment was carried out in a randomized block design in a 3 × 4 factorial scheme (genotypes x ways of nitrogen applying) with four replicates. The treatments consisted on the combination of three varieties: Agrobel 960, Agrobel 962 and V - 2000 and four different ways of nitrogen application: 100% at 20 days after sowing (DAS) - (0-100-0-0); 30% at sowing and 70% at 20 DAS - (30-70-0-0); 30% at sowing, 30% at 20 DAS e 40% at 40 DAS (30-30-40-0); 20% at sowing, 30% at 20 DAS, 30% at 40 DAS e 20% at 60 DAS (20-30-30-20). Measured variables were: height of the plant, height of the capitulum, diameter of the stem, diameter of the capitulum and achene yield. The ways of nitrogen application affected all components of yield. The N formulation (30-70-0-0) has determined the best results for the variables studied, but the form (30-30-40-0) provided results comparable to treatment (30-70-0-0); treatments where N was applied as (20-30-30-20) caused decrease in the performance of sunflower for all variables. The varietal effect was observed only for plant height and height of the capitulum. The highest yield of achene achieved was 1.639 kg ha-1, with no superiority for the hybrids Agrobel 960 and 962 in relation to the variety 122/V2000 Embrapa. Source

Prill M.A.S.,CCA UFRR | Neves L.C.,CCA UFRR | Tosin J.M.,Academica de Agronomia | Chagas E.A.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria
Revista Brasileira de Fruticultura | Year: 2012

This present study aimed to evaluate the effect of modified atmosphere (MA) by the use of plastic packaging for low density polyethylene (LDPE), the vacuum and the adsorption of ethylene, aiming the maintenance of the quality of bananas 'Prata Anã' cultived in Roraima. Analyses were performed each 5 days after harvest, up to 35 days. It was verified that the fruit under LDPE bags showed the lowest losses of fresh weight when compared to the others. Likewise, as the fruits packed in the presence of ethylene adsorption sachet had the best maintenance in the color peel, delay of the climacteric peak, as the delay in the starch degradation, lowest increments of soluble solids and titratable acidity, the lowest concentration of ethylene inside the LDPE bags and delay and decrease of enzyme activity. The combination of the use of LDPE bags with the sachet of potassium permanganate (KMnO4) resulted in the delay of ripening fruits of bananas 'Prata Anã', when stored at 12 °C. It can be attributed this beneficial effect by the presence of the sachet in the adsorption of ethylene and, consequently, in the action of ethylene in the fruit ripening, delaying the senescence of bananas 'Prata Anã'. Source

Pereira Uchoa S.C.,CCA UFRR | Ivanoff M.E.d.A.,Federal University of Roraima | Arcanjo Alves J.M.,CCA UFRR | Sediyama T.,Campus Universitario | Araujo Martins S.,Federal University of Roraima
Revista Ciencia Agronomica | Year: 2011

Potassium is a nutrient that positively affects achenes production within sunflower crop (Helianthus annuus L.) and its proper management is indispensable for better economical employment of this element and for a less environmental impact. Requirement nutritional between cultivars of the same species is distinct, even under the same conditions of cultivation. In order to assess production components of three sunflower cultivars submitted to different rates of potassium sidedressing an experiment was conducted in distrocohesive Yellow Latosol in the savanna of Roraima, in randomized blocks and factorial schema (3 × 5), with four replicates. Treatments consisted of the combination of three varieties (Agrobel 960, Agrobel 967 and Embrapa 122/V2000) and five rates of potassium side dressing (0; 30; 60; 90 and 120 kg ha-1). Effects of rates of K were independent from the effects of the cultivars. Hybrid Agrobel 967 presented superiority in productivity of of achenes, oil and oil content in relation to the hybrid Agrobel 960 and to the variety Embrapa 122/V2000. The most economic rate of potassium in sidedressing for productivity of achene and productivity oil was 74.5 and 80.1 kg ha-1, respectively. The maximum productions achieved by adding increasing rates of K2O as sidedressing were 2,038.3 kg ha-1 of achenes, with 52.5% of oil in seed and 1,079.3 kg ha-1 of oil yield. Source

Barbosa C.Z.d.R.,CCA UFRR | Smiderle O.J.,Embrapa Roraima | Alves J.M.A.,CCA UFRR | Vilarinho A.A.,Embrapa Roraima | Sediyama T.,Campus Universitario
Revista Ciencia Agronomica | Year: 2010

The main goal of this study was to evaluate the physical and physiological quality of soybean seeds, cultivar BRS Tracajá, 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 Roraima's 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 Tracajá during storage. Seeds of higher sizes from cultivar Tracajá (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 Tracajá cultivar, during storage, were obtained among seeds of larger sizes (6.0 and 6.5 mm). Seeds with larger sizes from BRS Tracajá (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. Source

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