Doses de potássio em cobertura na cultura da abóbora

Although there are recommendations for the fertilization of commercial squash crops, studies which connect the effect of topdressing potassium fertilization and yield are still rare. Thus, this study aimed at evaluating topdressing potassium doses on squash (Mirian hybrid) yield, in an experimental farm of the Universidade Estadual Paulista Júlio de Mesquita Filho, in São Manuel, São Paulo State, Brazil. The experimental design was randomized blocks, with five treatments (0.0 kg ha-1, 50.0 kg ha-1, 100.0 kg ha-1, 200.0 kg ha-1 and 400.0 kg ha-1 of K2O) and six replications. Plant growth parameters, yield and fruit quality were evaluated. After harvesting, plant (leaves + stem) and soil macronutrients were submitted to chemical analysis and data to variance and regression analysis. It was concluded that the highest yield resulted from the topdressing dose of 199.0 kg ha-1 of K2O. A reduction in calcium and magnesium contents in the plant canopy and a higher K+ content in the soil were observed for increasing K2O levels.

Adubação de cobertura na batata-doce com doses combinadas de nitrogênio e potássio

Balanced fertilizations with N and K often increase the performance of crops, however, when there is absence of one of these nutrients in poor soils, can reduce crop response to fertilization with the other. The objective of this work was to evaluate the productivity of sweet-potato, the amount of sweetpotato without quality, and leaf nutrients analysis, of sweet-potato crop fertilized with N and K. The trial was conducted in farming for commercial production, in Presidente Prudente, São Paulo State, during February-June 2007, in a dystrophic Ultisol of medium texture. The experimental design was a randomized complete block design, with four replications, on factorial 4 x 4: levels of 0, 30, 60 and 120 kg N ha-1 (urea source) combined with levels of 0, 30, 60 and 120 kg K2O ha-1 (KCl source), applied to 39 days after planting of the crop. The sweet-potato is responsive to topdressing application with nitrogen and potassium, however, the greatest increases in productivity occur when doses of N and K are combined. Fertilization with N and K not increase the amount of sweet-potato without quality marketing. The highest increase in productivity of sweet-potato is reached with topdressing combined with 100 kg N ha-1 plus 120 kg K2O ha-1.

Densidade populacional de pratylenchus spp. em pastagens de brachiaria spp. e sua influência na disponibilidade e na qualidade da forragem

The aim of this work was to evaluate the population density of Pratylenchus brachyurus and Pratylenchus zeae associated with Brachiaria brizantha, B. decumbens and B. humidicola and their influence on forage availability and quality. The experiment was conducte in the Hisaeda Farm, Terenos, MS, Brazil. Soil, roots and plant aerial part were harvest with ten replications each, in one square meter randomized sets encompassing three treatments: Good, Intermediary and Bad, visually characterized, considering the percentage of green material. P. brachyurus and P. zeae density were evaluated in soil and plant roots. Dry matter of green, dead and re-growth materials, plant nutritional status and forage quality were assessed in the aerial plant part. Soil fertility was determined in all harvested samples. Both nematode species were identified from all samples, with a larger numbe in the roots (between 87-311 P. brachyurus and 1-61 P. zeae.10 g-1) than in the soil (0-8 P. brachyurus and 1-39 P. zeae.200 cm-3), however, no significant differences were found in the number of specimens between treatments. Considering that these forage species are perennial and host Pratylenchus spp, there is a tendency to increase the population of these pathogens over time, becoming a serious phytosanitary problem.

Cloreto de potássio revestido em efeito residual no feijoeiro de inverno irrigado na região de cerrado

In order to maintain the nutrients available to plants have been studied controlled release fertilizers. In this context, the objective was to evaluate the residual effect of doses of potassium chloride, coated or not, applied in the corn crop, regarding the crop components and grains yield of irrigated winter common bean, cultivated in followed, in Cerrado region. The experiment was conducted in Selvíria - MS, Brazil, 51°22- west longitude and 20°22- south latitude, in a clayey Oxisol, in 2009 and 2010. A randomized block design with four repetitions was used, disposed in a factorial scheme 4 x 2, being: four K2O doses (0, 40, 80 and 120 kg ha-1) and two potassium sources (potassium chloride and coated potassium chloride by polymers) applied at sowing in the corn crop. The coated potassium chloride by polymers have the same residual effect as conventional KCl, because it provides results similar for the K and chlorophyll leaf contents, crop components and grains yield of winter common bean irrigated. The increment of potassium doses in the previous crop (corn) have residual effect, because it influenced positively the number of grains per plant in 2009 and increased linearly the chlorophyll leaf content and the grains yield of winter common bean irrigated in 2010, regardless of the source used for K.

Produção e qualidade em gérbera de vaso cultivada com cloreto e silicato de potássio

The Gerbera is an ornamental perennial herb, belonging to the Asteraceae family. Its cultivation, as well as the entire market for flowers and ornamental plants, is now in full expansion phase. The objective of this study was to evaluate the growth and quality Potted gerbera cultivar Red, according to sources and doses of potassium. The experiment was conducted in a greenhouse at UNESP/Botucatu. The experimental design was randomized blocks, using a 2x5 factorial arrangement, with two sources (potassium silicate and chloride) and five doses (0, 50, 100, 150 and 200 mg. L-1) 4 replications and 5 plants per plot. Weekly throughout the experimental period, assessments were made of the number of leaves (NL) and the diameter of the plant canopy (DP). at the end of the season and the reproductive cycle, at 42 and 60 days after acclimatization (DAA), respectively, were determined by leaf area (LA), mass (dry leaves (MSF), the dry mass of inflorescence (MSI) and total dry matter (TDM). at the point of marketing is that of open stamens, when the inflorescence had at least two rounds of open, releasing pollen, we determined the number of inflorescences (NI), the diameter of inflorescence (DI), the stem height (AH), the shank diameter (DH) and plant height (PH). Regardless of the doses, potassium silicate promoted greater diameter, leaf area, greater MSF, MST and increased stem height, characteristics that favor the sale of potted gerbera.

Características agronômicas e bromatolôgicas do milho submetido a adubações com potássio na produção de silagem

The aim was to evaluate levels and forms of application of potassium on the agronomic and alimentary characteristics of corn used for silage. The experiment was carried out at UNIFENAS during the agricultural year of 2008/2009. Fertilization at planting and sowing was performed manually using 120kg ha-1 P2O5 and 30kg ha-1 N, the potassium being applied according to the treatments. The experimental design used was of randomized blocks in a 4 x 2 factorial arrangement with four replications, using four amounts (0; 60; 90 and 120 kg ha-1) and two formsof application of K (100% at planting and 50% at sowing+50% coverage). The interaction between the factors of amount and forms of application of the potassium was not significant (p>0.05) for the variables studied: the main effect of each factor was then investigated. There was no effect (p>0.05) for K levels on the percentage of drymatter (DM) and bedded plants, DM and grain productivity and grain participation in the mass. The highest grain yield was obtained when using K at planting (p<0.05). High doses of potassium did not produce changes in DM, percentage of bedded plants, DM production, grain yield or grain percentage of the plant. The different levels and forms of application of potassium do not alter the alimentary characteristics of corn silage.

Sistemas de manejo e efeito residual do potássio na produtividade e nutrição do feijão-caupi

Cowpea [Vigna unguiculata (L) Walp] have great social and economic importance for the Para State. It grows well in areas with low precipitation and two crop cycles can be obtained annually. This study aimed to assess the effect of the residual fertilization from a previous culture (Sorghum bicolor L. Moench) and crop systems on cowpea yield and macronutrient concentration on leaves of three cowpea cultivars (BRSMilênio, BRS-Urubuquara e BRS-Guariba). The study was conducted at the UFRA. The treatments were two crop systems (minimum tillage and conventional), four levels of potassium (50, 100, 200 e 300 kg de KCl ha-1 applied to a previous sorghum culture) and the three cowpea cultivars. Treatments were organized as a three (4 x 2 x 3) factor experiment on a randomized complete block design. The soil was a yellow latosol. In each experiment plot five plants were selected to determine shoot dry matter and foliar nutrient concentration. Grain yield was determined after harvesting all plants on the experiment plot. The residual KCl fertilization affected foliar nutrient content, but did not affect shoot dry mass or yield of grain. Yield was higher in the minimum tillage system. Highest yield (1590 kg ha-1) was recorded int the cv. 'Guariba' when 100 kg of KCl ha-1 had been used in the previous crop. The highest content of leaf N and K was found in cowpea under minimum tillage system. The amount of P and Mg were higher in the conventional system whereas the amount of Ca did not change.

Aspectos físicos e sociais da geografia da disponibilidade hídrica municipal no Brasil

In managing water resources, indexes are used to simplify and quantify available information as well as report the characteristics of a region under study. These indexes may be extremely demanding concerning information required, or very simple, and the water poverty index and Falkenmark index are examples of both extreme situations, respectively. Searching for an index that considers regional and local complexities and information available in developing countries, a new index was developed to evaluate the population accessibility to water resources. This new index combines the Human Development Index and Falkenmark Index and geographic information systems. The results are presented in figures which show the situation at national level, highlighting that the Northeast and Southeast regions are the most vulnerable in Brazil.

Disponibilidade de fósforo em função da aplicação de calcário e silicatos em solos oxídicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da liberação de potássio por resíduos do benefício de café

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fontes e doses de potássio na cultura do café (Coffea arabica L.)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Disponibilidade de fósforo para a soja cultivada sobre braquiária

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Liberação de nitrogênio e potássio da palha de café em função da adubação nitrogenada

Pós-graduação em Agronomia (Agricultura) - FCA

Eficiência agronômica de fertilizantes organominerais sólidos e fluidos em relação à disponibilidade de fósforo

Pós-graduação em Agronomia (Agricultura) - FCA

Estresse hídrico e adubação silicatada em batata (Solanum tuberosum L.) cv. Bintje

Pós-graduação em Agronomia (Agricultura) - FCA