Sebastião Alberto de Oliveira

Acúmulo de nitrato em alface em função da adubação, horário de colheita e tempo de armazenamento

The experiment was carried out in Brasilia, Brazil, from January to March 2004, aiming to evaluate the level of nitrate in lettuce, cv. Veronica, as a result of fertilization, harvesting time and storage period (8oC). We used the ramdomized blocks experimental design in a factorial 5 x 4 x 4, with four replicates. The five fertilization treatments tested were: 1,5 kg m-2 of chicken manure (T1); 3,0 kg m-2 of cattle manure (T2); mineral, as a result of soil chemical analysis - M (T3); M with 1,5 kg m-2 of chicken manure (T4); and M with 3,0 kg m-2 of cattle manure (T5). The harvesting times were 7 and 11 a.m., and 3 and 6 p.m. The storage periods were 0; 3; 5 and 7 days. The treatments T1 and T4 resulted in plants with the highest levels of nitrate, 1240,12 and 1303,66 mg NaNO3 kg-1, respectivelly, while T2 resulted in the lowest nitrate level, 547,26 mg NaNO3 kg-1. However, when cattle manure was added to M (T5), an increase of 2,18 times was observed in the nitrate level (1195,25 mg NaNO3 kg-1). Plants harvested at 7 a.m. showed the lowest levels of nitrate, suggesting that it is the best moment to harvest lettuce in the Distrito Federal region. During the storage period of seven days, nitrate level was reduced by 29,3%.

Adubo fosfatado revestido com polímero e calagem na produção e parâmetros morfológicos de milho

The low availability of phosphorus in acid soils, such as those of the Cerrado, requires the efficient management of phosphorus fertilization. The use of technologies that increase the efficiency of phosphorus use is an alternative that can be adopted, provided the reality of Brazilian soils is taken into consideration. This work was carried out to evaluate the effect of polymer-coated phosphate fertilizer associated with liming on the production and morphological parameters of corn crops. The study was conducted in the field, in a red-yellow latosol. The experimental design was of randomized blocks arranged in a 2 x 4 factorial, with three replications. The treatments resulted from a combination of two sources of phosphorus (conventional MAP and polymer-coated MAP - Kimcoat ®) at four levels of saturation (27%, 40%, 50% and 60%). The sources of phosphorus displayed differences dependent on the base levels of saturation. The polymer-coated MAP improved the performance of corn, for productivity, total dry-matter yield and plant height, in relation to conventional MAP. The major differences were observed at base saturation levels of 40% and 50%, in which the coated MAP promoted an increase in grain yield of 3.40 and 3.48 t ha-1, respectively, compared to conventional MAP.

Preliminary DRIS norms for sugarcane developed from a low number of samples

The objective of this work was to evaluate the feasibility of developing preliminary DRIS norms from a low number of leaf samples of sugarcane grown on a homogeneous soil series, as an alternative to diagnose the nutritional equilibrium of the crop. The research was carried out in Central Azucarero Portuguesa sugarcane mill, Portuguesa state, Venezuela. From May to July 2004, composite leaf samples from 32 different sugarcane-producing areas were collected and analyzed for nitrogen, phosphorus, calcium, magnesium, boron, copper, iron, manganese, zinc and sodium. All the sampled areas were from the Agua Blanca series (Aquic Haplustoll) and had a high historical record of stalk productivity. A normal data bank was obtained, which provided confidence for the development of preliminary DRIS norms. These norms showed coincidences and differences with previously reported ones in the literature. The content of sodium as a diagnostic norm was reported. A low number of leaf samples are sufficient to develop norm data banks and preliminary DRIS norms for nutritional diagnosis of sugarcane.

Balanço nutricional e incidência de queima de bordos em alface produzida em sistema hidropônico - NFT

Aiming to evaluate the effect of nutrients balance in lettuce tip burn incidence, an experiment was carried out in Brasilia, Brazil, from October 2001 until June 2002, in two phases. During the first phase four solution concentrations (0.5; 1.5; 2.5 and 4.0 mS.cm-1) were evaluated to determine the concentration with the highest percentage of tip burn. During the second phase, a solution concentration of 4,0 mS.cm-1 and foliar applications of three calcium sources (CaCl2, CaB2® and CaNO3) were applied to plants to prevent tip burn. Nutritive solution proposed by Castellane and Araujo in 1995 was used in both phases. The evaluated parameters were percentage of plants with tip burn incidence, leaf nutrient concentration and plant fresh weight. In the first trial the more concentrated (4,0 mS.cm-1) and the less concentrated (0,5 mS.cm-1) nutritive solution presented the highest percentage of plants with the symptoms. In the second trial, the zinc deficiency induced by boron high concentration, was responsible for the symptoms. This was the reason why calcium leaf application was not effective on reducing foliar symptoms.

Absorção de nutrientes e resposta à adubação em linhagens de tomateiro

Twenty nine processing tomato inbred lines were evaluated for their efficiency in nutrient uptake and in their response to fertilization. Two field assays were carried out at Embrapa Hortalicas, Brazil, with distinct fertilization dosages in 2006. In the first assay 1/3 of the total fertilization was applied when compared with the second assay. The experiments were conducted using a completely randomized design with three replications. The criteria to rank the inbred lines in both assays were the DRIS (Diagnosis and Recommendation Integrated System) index value and fruit yield. The critical values in order to distinguish efficient versus non-efficient as well as responsive versus non-responsive inbred lines were the average increase in both DRIS index value and fruit yield. Differences were detected among inbred lines for the uptake efficiency for all nutrients and for response to fertilization. The inbred lines 03, 40, 09 and 22 were classified as responsive to fertilization and efficient in N uptake; the lines 03, 04, 09, 13, 15 and 29 were for P; 03, 05, 10, 21, 22, 25 and 27 for K, 05, 10, 21, 22, 25, 27 and 29 for Ca; 04, 13, 15, 27 and 29 for S and B; 03, 05, 09, 10 and 27 for Cu. The inbred lines with the best performance were 27 in relation to nutrient absorption, and the lines 03, 04, 05 and 29 in relation to fertilization response.

Propriedades microbiológicas do solo e disponibilidade de nitrogênio para milho em monocultura e em consórcio com forrageiras

The objective of this work was to evaluate the effects of corn (Zea mays) in monoculture and intercropped with forage on soil microbiological properties and nitrogen availability under no-tillage in the Cerrado (Brazilian savanna). The experiment was carried out from the 2007/2008 to the 2010/2011 crop season, in a Latossolo Vermelho-Amarelo distrófico (Typic Haplustox). A randomized complete block design with three replicates was used, with the following treatments: corn in monoculture; corn intercropped with Panicum maximum; corn intercropped with Urochloa humidicola; P. maximum in monoculture; and U. humidicola in monoculture. Soil samples were taken at 0.00–0.05, 0.05–0.10, 0.10–0.20, and 0.20–0.30-m soil depths, in the begining and in the end of the last crop season. The intercropping systems of corn increased soil nitrogen availability, but did not alter total nitrogen and organic carbon contents in the soil, when compared to corn in monoculture. Corn intercropped with P. maximum increased soil microbial biomass nitrogen and microbial nitrogen quotient, in comparison to corn in monoculture, as well soil as microbial biomass carbon in the surface soil layer, when compared to corn intercropped with U. humidicola.