Nitrogen (N) and potassium (K) are usually found in higher concentrations than other macronutrients in apple (Malus x domestica Borkh) fruits and are most frequently associated with changes in fruit quality. The aim of this article was to evaluate the effects of N and K fertilization on some fruit quality attributes of Fuji apple. The experiment was conducted at Sa ˜o Joaquim, State of Santa Catarina, Brazil, during 2004 and 2005. A factorial design was used with N and K annual fertilizer rates (0, 50, 100, and 200 kg ha 21 of N and K 2 O) replicated in three orchards. Fifteen days prior to harvest, three fruit samples were collected from each treatment and site. One sample was used for total soluble solid content (TSS), titratable acidity, pulp firmness, and fruit color parameter analyses, and the other samples were refrigerated in a conventional atmosphere for 3 and 6 months for subsequent determination of fruit quality. Nitrogen fertilization negatively affected fruit color, flesh firmness, and TSS content. These same variables were positively affected by K fertilization, except for flesh firmness.

N o estado de Santa Catarina, devido a suas variadas condições de altitude e proximidade ao oceano, é possí-vel cultivar-se batata durante o ano todo. O planalto sul de Santa Catarina é uma das regiões produtoras do estado onde o plantio de batata, principalmente com finalidade para semente, representa uma importante fonte de renda e trabalho. Os produtores de batata-semente, na grande maioria, adotam alta tecnologia para a obtenção de produtividade economicamente viável, sendo que entre os componentes dos custos de produção aparecem os fertilizantes, representando 24,1% do custo total (Souza et al., 1999).Os solos do planalto sul caracterizam-se principalmente pela elevada acidez e baixos teores de fósforo (P) disponível, o que torna necessária a aplicação de quantidades elevadas de fertilizantes. A alta capacidade de resposta da cultura da batata à adubação em comparação a outras culturas pode ser atribuída ao elevado potencial de produção, ao ciclo curto e ao sistema radicular re- (Sangoi & Kruse, 1994).Face aos altos rendimentos, a extração de nutrientes é relativamente alta. Estima-se que para uma produtividade de 30 t ha -1 de tubérculos, têm-se exportações aproximadas de 120 kg de potás-sio (K), 100 kg de nitrogênio (N) e 14 kg de fósforo (Reis Jr. & Monnerat, 2001). No entanto, as quantidades dos diversos nutrientes absorvidos pela planta e extraídos pelos tubérculos dependem de uma série de fatores, entre os quais podem ser citados a região de cultivo, as condições climáticas, o manejo da cultura, a cultivar, o potencial de produção, entre outros (Sangoi & Kruse, 1994).Apesar do P ser menos extraído que o K e o N, os solos da região do planalto sul de Santa Catarina são naturalmente pobres em P. Além disso, no cultivo da batata, o pH do solo é limitado ao máximo de 5,5, uma vez que valores superiores estão associados à ocorrên-cia de doenças como a sarna da batata (Sangoi & Kruse, 1994). Em valores de pH igual ou menores que 5,5 pode ocorrer alta fixação de P no solo e, conseqüentemente, a diminuição da disponibilidade deste nutriente para as plantas.Jenkins & Hakoomat (1999) observaram alta resposta da batata à adubação fosfatada e também observaram diferenças entre os cultivares, sendo que aqueles com sistema radicular limitado possuíam baixa capacidade de explorar os nutrientes do perfil do solo. O volume de raízes é particularmente importante para aqueles nutrientes que são relativamente imóveis no solo, tal como o P.O K é indispensável para a translocação de acúcares e síntese de amido (Reis Jr. & Fontes, 1996), sendo o nutriente mais absorvido pela batata (Reis Jr. & Monnerat, 2001). Embora o K seja importante para o aumento do rendimento de tubérculos (Moinuddin & Bansal, 2005; Reis Jr. & Fontes, 1996), o excesso pode reduzir o peso específico (Reis Jr. & Fontes, 1996) e o teor de amido dos mesmos (Westermann et. al. 1994a).O N é essencial para a formação da clorofila, proteína e muitas outras mo- RESUMOO trabalho foi realizado no município de São Joaquim, estado de Santa Catarina, em do...

Nitrogen (N) and potassium (K) are closely related to orchard productivity, since they are usually found in higher concentrations than others macronutrients in apple (Malus × domestica Borkh) fruits. This research was carried out to assess the effect of eight years of soil additions of N and K on yield, fruit size and mineral composition of 'Fuji'/Marubakaido apple in São Joaquim, State of Santa Catarina, Southern Brazil. A factorial design was used with N and K annual fertilizer rates (0, 50, 100, 200 kg ha -1 of N and K 2 O) replicated in three orchards from 1998 to 2006. Yield was estimated by multiplying the total number of fruit per tree by the mean weight of 100 randomly sampled fruit. Fifteen days prior to harvest, 24 fruit pulps were analyzed for N, K, Ca and Mg contents. Increases in yields were noticed in five and four years, due to the N and K fertilizer additions, respectively. Fruit size was more affected by K than by N fertilization. Fruit mineral composition was affected by both N and K fertilization. N concentration and N:Ca ratios were enlarged by N fertilization. K concentration and K:Ca ratios were also enlarged by K fertilization. Ca fruit concentration was reduced by N fertilization and often by K. Ca-related fruit disorders were not observed even after 180 days storage. However, N and K fertilization affected Ca nutrition. Thus, when fertilizing with N and K, it is imperative to use combined practices in order to offset the detrimental effect that these nutrients may cause on Ca concentration in the fruit. Key words: Malus domestica Borkh, fertilization, production, nutrition de N e de K 2 O) e repetidas em três pomares comerciais. O rendimento foi estimado a partir da contagem do número total de frutos por planta e multiplicado pelo peso médio de 100 frutos amostrados aleatoriamente por parcela. Quinze dias antes da colheita, 24 frutos foram amostrados para fins de determinação das concentrações de N, K, Ca e Mg. As adubações nitrogenada e potássica aumentaram o rendimento da macieira em cinco e quatro dos oito anos avaliados, respectivamente. O tamanho dos frutos foi mais afetado pela adubação potássica que pela nitrogenada. As adições de N e K influenciaram a composição mineral dos frutos, incrementando suas concentrações e as relações N:Ca e K:Ca. A concentração de Ca nos frutos foi reduzida pela adubação nitrogenada e frequentemente pela potássica. Distúrbios fisiológicos relacionados com a deficiência de Ca não foram observados, mesmo após 180 dias de armazenagem. Entretanto, a nutrição do Ca foi influenciada pelas adubações nitrogenada e potássica. Por isso, ao aplicar-se N e K deve-se combinar práticas nutricionais que compensem a redução da concentração de Ca nos frutos que esses nutrientes promovem. ADUBAÇÕES ANUAIS COM NITROGÊNIO E POTÁSSIO POR LONGO PRAZO INFLUENCIAM O RENDIMENTO E A COMPOSIÇÃO MINERAL DE MAÇÃS 'FUJI' RESUMO: O nitrogênio (N) e o potássio (K) são os nutrientes mais exportados pelas maçãs (Malus

-The aim of this study was to evaluate the response to phosphorus (P) and potassium (K) fertilization and to establish the critical levels of P and K in the soil and in the plant tissue in pear trees. Two experiments were conducted in São Joaquim (SC), Brazil. In experiment 1, the plants received annually the application of increasing rates of phosphate fertilizer (0, 40, 80, 120 and 160 kg P 2 O 5 ha -1 ), while in experiment 2, increasing rates of potassium fertilizer (0, 40, 80, 120 and 160 kg K 2 O ha -1 ) were applied annually. In the two experiments, soil was collected annually from the 0-10, 10-20 and 0-20 cm layers, and the available P (experiment 1) and exchangeable K (experiment 2) content was analyzed. Whole leaves were collected annually, which were subjected to analysis of total P (experiment 1) and total K (experiment 2) content. The number and weight of the fruits per plant and fruit yield were evaluated. Application of P on the soil planted with pear trees increased the nutrient content in the soil and, in most crop seasons, in the whole leaf, but it did not affect the yield components and fruit yield. The application of K on the soil with pear trees increased the nutrient content in the soil and, in most of the crop seasons, in the whole leaf, but the potassium content in the whole leaf decreased in the crop season with greater fruit yield. The yield components and fruit yield were not affected by K fertilization. Index terms: Pyrus communis L., sufficiency level, phosphate fertilization, potassium fertilization, yield. RESPOSTA DA PEREIRA À APLICAÇÃO DE FÓSFORO E POTÁSSIORESUMO -O trabalho objetivou avaliar a resposta à adubação com fósforo (P) e potássio (K) e estabelecer o nível crítico no solo e no tecido de P e K em pereira. Dois experimentos foram conduzidos em São Joaquim (SC). No experimento 1 as plantas receberam anualmente a aplicação de doses crescentes de fertilizante fosfatado (0; 40; 80; 120 e 160 kg de P 2 O 5 ha -1 ), enquanto no experimento 2 foram aplicadas anualmente doses crescentes de fertilizante potássico (0; 40; 80; 120 e 160 kg de K 2 O ha -1 ). Nos dois experimentos foi coletado anualmente solo nas camadas de 0-10; 10-20 e 0-20 cm, onde foi analisado o teor de P disponível (experimento 1) e K trocável (experimento 2). Anualmente foram coletadas folhas completas que foram submetidas à análise do teor total de P (experimento 1) e K (experimento 2). Avaliaram-se o número e a massa dos frutos por planta e a produção de frutos. A aplicação de P no solo cultivado com pereira incrementou o teor do nutriente no solo e, na maioria das safras, na folha completa. Porém, o incremento do teor de P disponível no solo e na folha não foi acompanhado de aumentos nos componentes de produção e na produção de frutos, impossibilitando o estabelecimento do nível crítico de P no solo e no tecido. A aplicação de K no solo aumentou o teor do nutriente no solo e, na maioria das safras, na folha completa da pereira, mas o teor de K na folha completa diminuiu na safra com maior produção d...

This study evaluated the diversity of cultivable plant growth-promoting (PGP) bacteria associated with apple trees cultivated under different crop management systems and their antagonistic ability against Colletotrichum gloeosporioides. Samples of roots and rhizospheric soil from apple trees cultivated in organic and conventional orchards in southern Brazil were collected, together with soil samples from an area never used for agriculture (native field). Bacteria were identified at the genus level by PCR-RFLP and partial sequencing of the 16S rRNA, and were evaluated for some PGP abilities. The most abundant bacterial genera identified were Enterobacter (27.7%), Pseudomonas (18.7%), Burkholderia (13.7%), and Rahnella (12.3%). Sixty-nine isolates presented some antagonist activity against C. gloeosporioides. In a greenhouse experiment, five days after exposure to C. gloeosporioides, an average of 30% of the leaf area of plants inoculated with isolate 89 (identified as Burkholderia sp.) were infected, whereas 60 to 73% of the leaf area of untreated plants was affected by fungal attack. Our results allowed us to infer how anthropogenic activity is affecting the bacterial communities in soil associated with apple tree crop systems, and to obtain an isolate that was able to delay the emergence of an important disease for this culture.

No abstract

The application of rest breaking agents to compensate the lack of chilling is a common practice in apple orchards in Southern Brazil. However, its necessity in areas of greater chilling accumulation has been questioned over the years. The aim of this study was to investigate the performance of 'Maxi Gala' apple in response to different budbreak promoters in São Joaquim, SC.The study was performed in the growing seasons of 2013/2014, 2014/2015, and 2015/2016. Plant material consisted of 10-year-old 'Maxi Gala' apple trees grafted on the rootstock 'M.9', arranged in a randomized complete block design with five replicates in the 2013/2014 and 2014/2015 growing seasons and six replicates in the 2015/2016 season. Treatments consisted of Erger ® , combined with either calcium nitrate or mineral oil, at different rates; and hydrogen cyanamide combined with mineral oil. Treatments were applied when buds were between the stages A (dormant bud) and B (swollen bud; silver tip). The influence of treatments on flowering, budbreak, yield components, and fruit quality was assessed. Flowering was little affected by treatments, while axillary budbreak was consistently improved in the year of insufficient chilling accumulation. Besides, the combination Erger ® (2% and 3%) + calcium nitrate (2% and 3%) and Erger ® (1%) + mineral oil (3%) induced similar axillary budbreak as hydrogen cyanamide + mineral oil. Fruit quality attributes were not affected by treatments.

Summarygypsum does not affect the soil negative charges and maintains sulfate in the soil solution, making it one of the cheapest products to increase Ca activity in soil solution, especially in the deeper soil layers. Higher Ca levels in the soil solution can increase the uptake of this nutrient by apple trees, reducing the risk of physiological disorders caused by Ca deficiency. this study assessed the effect of long-term gypsum application on some soil properties and on the chemical composition of leaves and fruits of an apple cultivar susceptible to fruit disorders associated with low Ca. the experiment was conducted in São Joaquim, in the South of brazil, from 2001 to 2009. gypsum rates of 0, 1.0, 2.0 and 3.0 t ha -1 were annually broadcast over the soil surface, without incorporation, in an apple orchard with cultivar ´Catarina´, planted in 1997. gypsum application over eight consecutive years had no effect on soil exchangeable K and al to a depth of 80 cm, but increased exchangeable Ca in the sampled layers (0-10, 10-20, 40-60 and 60-80 cm), while exchangeable mg decreased only in the surface layer (0-20 cm). gypsum did not affect the concentration of any nutrient in the fruits, including Ca. the same was verified in the leaves, except for mg which decreased with increased gypsum rate. despite increasing the availability of Ca in the soil profile to a depth of 80 cm, gypsum was not effective to increase the Ca content in leaves and fruits of an apple cultivar susceptible to Ca deficiency grown in an appropriately limed soil. index terms: downward movement, cations, nutritional status, calcium.