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.

At least two indigenous species of the Bemisia tabaci complex are present in Brazil

Bemisia tabaci is one of the most important global agricultural insect pests, being a vector of emerging plant viruses such as begomoviruses and criniviruses that cause serious problems in many countries. Although knowledge of the genetic diversity of B. tabaci populations is important for controlling this pest and understanding viral epidemics, limited information is available on this pest in Brazil. A survey was conducted in different locations of São Paulo and Mato Grosso states, and the phylogenetic relationships of B. tabaci individuals from 43 populations sampled from different hosts were analysed based on partial mitochondrial cytochrome oxidase 1 gene (mtCOI) sequences. According to the recently proposed classification of the B. tabaci complex, which employs the 3.5% mtCOI sequence divergence threshold for species demarcation, most of the specimens collected were found to belong to the Middle East-Asia Minor 1 species, which includes the invasive populations of the commonly known B biotype, within the Africa/Middle East/Asia Minor high-level group. Three specimens collected from Solanun gilo and Ipomoea sp. were grouped together and could be classified in the New World species that includes the commonly known A biotype. However, six specimens collected from Euphorbia heterophylla, Xanthium cavanillesii and Glycine maxima could not be classified into any of the 28 previously proposed species, although according to the 11% mtCOI sequence divergence threshold, they belong to the New World high-level group. These specimens were classified into a new recently proposed species named New World 2 that includes populations from Argentina. Middle East-Asia Minor 1, New World and New World 2 were differentiated by RFLP analysis of the mtCOI gene using TaqI enzyme. Taq I analysis in silico also differentiates these from Mediterranean species, thus making this method a convenient tool to determine population dynamics, especially critical for monitoring the presence of this exotic pest in Brazil. © 2012 Blackwell Verlag, GmbH.

Optimization of the immobilization of sweet potato amylase using glutaraldehyde-agarose support. Characterization of the immobilized enzyme

A simplified procedure for the preparation of immobilized beta-amylase using non-purified extract from fresh sweet potato tubers is established in this paper, using differently activated agarose supports. Beta-amylase glutaraldehyde derivative was the preparation with best features, presenting improved temperature and pH stability and activity. The possibility of reusing the amylase was also shown, when this immobilized enzyme was fully active for five cycles of use. However, immobilization decreased enzyme activity to around 15%. This seems to be mainly due to diffusion limitations of the starch inside the pores of the biocatalyst particles. A fifteen-fold increase in the Km was noticed, while the decrease of Vmax was only 30% (10.1 U mg-1 protein and 7.03 U mg-1 protein for free and immobilized preparations, respectively). © 2013 Elsevier Ltd.

Atividade inseticida e Modos de Ação de Extratos Vegetais Sobre Mosca Branca (Bemisia tabaci)

Insecticide potential and efficaciousness of vegetal extracts concentrations from six botanic families in three different modes were analyzed on the nymphs of the silverleaf whitefly Bemisia tabaci (Genn. 1889) on a tomato plantation Lycopersicon esculentum Mill. Nymph breeding was kept in cherry tomato shrubs. Test solutions were obtained from successive extractions with ethanol and evaporation in a rotary evaporator. Tests consisted of 10 solutions in four concentrations (500; 1,000; 1,500 and 3,000 μg/mL) and control treatment (distilled water + 1% DMSO) under three different modes of activity, namely, contact, translaminar and systemic. Experimental design was totally randomized with four repetitions and eleven treatments. Means were compared by Scott-Knott test at 5% probability and lethal concentrations (CL50) were calculated by POLO. In the case of contact activity mode, all extracts had efficiency above 50% with the highest concentration (3,000 μg/mL) in which the highest efficiency for all extracts tested was verified. There was a need for dose increase in translaminar activity mode for similar results, whereas in the case of systemic activity the best performance was obtained with extracts of Nerium oleander, Derris amazonica and Ipomoea carnea. Extracts of the last two caused a higher percentage when compared with that of other extracts in all activity modes lower than CL50.

Eficiência de herbicidas inibidores da ALS e PROTOX sob condições de déficit hídrico no comportamento bioquímico de plantas daninhas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Intervalos de chuva na eficiência de herbicidas aplicados em pós-emergência

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

Eficácia do herbicida mesotrione aplicado no sistema de cana crua

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeitos de óleos nas características físicas e químicas da calda de aplicação e na ação da atrazina

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da absorção do amicarbazone e intoxicação em cana-de-açúcar e plantas daninhas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influência do amicarbazone no fotossistema II de plantas daninhas e cana-de-açúcar

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Velocidade de absorção do glufosinate e seus efeitos em plantas daninhas e algodão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito da época e local de semeadura na interferência das plantas daninhas na cultura do amendoim

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Lixiviação de sulfentrazone e amicarbazone com adição de óleo em resposta à precipitação e emergência de Ipomea spp. em função da profundidade de semeadura e cobertura com palha

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Glyphosate, suas combinações com outros herbicidas e formulações no controle de plantas daninhas importantes na cultura da soja

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Efeito de adjuvantes nas propriedades físico-químicas da água e na redução de deriva em pulverizações sobre diferentes espécies de plantas daninhas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)