Cancro do castanheiro: a luta cultural na redução do inóculo e manutenção sustentada dos soutos

Cryphonectria parasitica fungo Ascomiceta da ordem Diaphortales e família Valsaceae foi noticiado pela primeira vez em Portugal em 1989. Teve uma dispersão muito rápida em todas as regiões de castanheiro existindo focos com forte incidência da doença de maior ou menor dimensão em todos os locais onde foi introduzido. Este trabalho teve como objectivo avaliar a eficácia da extirpação dos cancros como meio de luta contra o cancro do castanheiro e estudar as características da população de C. parasitica. A extirpação dos cancros quando aplicada a sistemas de exploração de castanheiros para fruto revelou ser muito eficaz, necessitando no entanto de um acompanhamento continuado para ser eficiente. A população de C. parasitica evidenciou grande uniformidade nas características morfológicas relacionadas com a cor e crescimento dos isolamentos e maior variabilidade na produção de esporos, evidenciando ainda uniformidade em relação à sensibilidade ao cobre. Todos os isolamentos foram incluídos no mesmo grupo de compatibilidade vegetativa (VCG) e identificado como VCG 2-P o mais frequente na população de C. parasitica em Portugal

Carências de boro no interior - norte e centro - de Portugal

In Portugal, boron deficiency has been observed almost everywhere, in particular in the interior of the country, causing severe crop damage. In the 1950’s, the growth anomalies in the Douro vineyards were recognised as a boron deficiency (called ´maromba’). From the 1980’s onwards systematic studies have been carried out in the northern and central interior of Portugal with the purpose of identifying and correcting this deficiency in fruit trees and forest/agroforest species. In this review paper an inventory of geological/lithological formations and soil groups is carried out where the boron shortage was most often detected. The environmental conditions that enhanced the occurrence of boron deficiency were reviewed. Based on studies carried out in these regions, the deficiency symptoms of selected trees were described, and also the boron concentrations in soils and leaves in which the symptoms had been observed were recorded. Experimental results of boron fertilisation in terms of growth or yield increase of crops were presented. Finally, an attempt is made to explain perplexities arisen from unexpected plant reactions, either due to the deficiency or to boron application, since the emergence of ´maromba’ in the 19th century until the present. In addition, some strategies for correction of scarcity of this micronutrient are suggeste

Aspectos metodológicos e desafios da Coorte On-line Comportamento Alimentar e Saúde Mental (COCASa) de docentes e discentes universitários durante a pandemia da COVID-19

O distanciamento social adotado para controle da COVID-19 obrigou Instituições de Ensino Superior (IES) a aderirem a novas estratégias para realização das atividades acadêmicas e muitas pesquisas passaram a ser realizadas em ambientes virtuais. O objetivo deste artigo é descrever os aspectos metodológicos e principais desafios enfrentados para a execução do projeto COCASa, um estudo de coorte on-line sobre comportamento alimentar e saúde mental de docentes e discentes de IES do Brasil. O estudo foi iniciado em julho de 2020 e acompanhará os participantes por dois anos. Adotou-se amostragem não probabilística estratificada proporcional com a utilização de escalas, de inquérito alimentar e de questões estruturadas elaboradas pela equipe do projeto. Entre os participantes do baseline, 4.074 discentes e 2.210 docentes iniciaram o questionário e, respectivamente, 76,8% e 85,1% finalizaram o preenchimento. Em ambos os grupos, a maior participação foi de mulheres (docentes: 66,7% e discentes: 76,2%) e residentes nas regiões Nordeste (docentes: 37% e discentes: 50,9%) e Sul (docentes: 27,1% e discentes: 22,5%) do Brasil. A pesquisa on-line amplia a possibilidade de recrutamento de participantes e alcança limites territoriais com menor demanda por financiamento. Durante a pandemia da COVID-19, o uso do ambiente virtual tornou-se uma estratégia viável e acessível para a manutenção das atividades de pesquisa, configurando-se como uma provável tendência a ser adotada pela comunidade científica

Potassium supplying capacity of northeastern Portuguese soils

In Portugal, the response to K application is often inconsistent with the Egner-Riehm values for available K. This is partly related to high K reserves of some soils. Twenty surface soils representative of different parent materials from NE Portugal were studied to determine their K supplying capacity. Continuous cropping with perennial ryegrass permitted the assessment of the relative ability of soils to release non-exchangeable K. Soils were classified in the range of available K from medium to very high. However, their ability to supply K in the short and long term are very different. In some soils K status measured by plant growth does not fall appreciably, whilst others are rapidly exhausted, and 30% of them are very deficient in K. The supplying capacity varied both with the nature of the parent material and the degree of weathering. The soils deficient in K are those derived from basic rocks and those with more weathered clay minerals. This is the case of the soils with the largest content of organic matter where the dominant clay minerals were kaolinite and vermiculite. Soils that have the highest capacity for supplying K are highly micaceous, like those developed from mica schists, phyllites or river alluvium. In fact the amount of K released from non-exchangeable form is well correlated with the amount of illite in the clay fraction. Soil types and K buffer power coupled with available K must be taken into account when planning any application of K

Early diagnosis of boron deficiency in chestnut

This study aims to identify an alternative plant tissue to be used in the early diagnosis of boron (B) deficiency in chestnut (Castanea sativa Mill.). A B-deficient orchard was selected, and 16 trees were submitted to two levels of B fertilization. When flowers were in bloom, the following tissues were sampled: leaves, androgynous catkins and flowers. There was a significant increase in B content in plant tissues due to B application. In July, the highest B content was observed in flowers in B0, but leaves had the greatest content in B1. Boron content in the tissues collected in July was positively correlated with B contents in leaves sampled in September. Foliar B concentrations, irrespective of the sampling period, were correlated with chestnut productivity, while the other tissues did not. These results suggest that the leaves, sampled in bloom, were the most efficient tissue for the early diagnosis of B deficienc

Boron application on a chestnut orchard: effect on yield and quality of nuts

Although boron (B) deficiency in chestnuts (Castanea sativa Mill.) has been identified in Portugal and B fertilization was carried out in some orchards, the post-treatment evaluations have not been made to date. So the objective of this trial was to confirm the B deficiency and to quantify the effect of B applications to the soil on nut yield and quality. In October 2006, a fertilizer trial was established in a 15 year-old orchard in a very acid soil derived from siliceous schists. Soil liming and a basal fertilization were carried out in 16 trees and two levels of sodium tetraborate (Granubor, 14.6% B) were applied to eight trees: control (B0) and 100 g of Granubor per tree (B1). In the beginning of September chestnut leaves were collected from five trees and analyzed for macroand micronutrients. Nut productivity was measured per tree and some nut quality parameters were evaluated, including the chemical composition of the kernel (soluble sugars, starch, total fiber, crude protein, and crude fat) in 2007, and dry matter, nut caliber, and fruit damage in 2007 and 2008. Boron fertilization of chestnuts significantly increased nut production: 75% in the first year (8 kg and 14 kg per tree, respectively, in the B0 and B1) and, in the second year, was over four times higher (4 kg and 17 kg per tree, respectively, in the B0 and B1). No significant differences were found in dry matter, nut caliber, nut damage and chemical composition of the kernel in the first year, but in the second year lower fruit damage by chestnut tortrix (P<0.0089) was observed. Foliar analyses exhibit relatively low B concentrations in the control trees (average value of 8 mg kg −1 ) in both years, while in the fertilized trees the foliar B concentration were in average 61 mg kg −1 in the first year, and 34 mg kg −1 in the second year. The large drop in the foliar B concentration in the second year suggests the need to monitoring the nutrient status of chestnut orchards or more frequente of B application than usual practice

Diagnóstico precoce da carência de boro em castanheiro: Selecção de tecido indicador Early diagnosis of boron deficiency in chestnut: sellection of plant tissue indicator

O objectivo deste estudo foi identificar um tecido indicador na detecção precoce da carência de B no castanheiro, que permita a correcção atempada da carência de B. Num souto com deficiência de B instalou-se um ensaio em que se utilizaram dois níveis de B: B0, e B1 onde se aplicou 100 g de Granubor (14,6%) por árvore. Colheu-se no início de Julho, quando as flores femininas estavam em plena floração, os seguintes tecidos: folhas completamente expandidas, amentilhos androgínicos e flores femininas. No período normal de colheita (Setembro), voltou-se a amostrar as folhas. Determinaram-se as concentrações de macro e micronutrientes nos diversos tecidos. As concentrações de B nos tecidos amostrados em Julho revelaram-se correlacionadas com as de B na folha colhida em Setembro. Enquanto as concentrações de B na folha, em Setembro e em Julho, estavam correlacionadas com a produção de castanha, os outros tecidos não mostraram correlação significativa. Assim, estes resultados sugerem que a folha, colhida em Julho, foi o órgão que se mostrou mais eficiente no diagnóstico precoce da carência de B.This study aims to identify a plant tissue indicator to be used in the early diagnosis of B deficiency in chestnut, which provides a tool to decide the correction measures to be applied in time to improve yield. An orchard with apparent B deficiency was selected, and two levels of B fertilization, B0 and B1- 100 g/tree of Granubor (14.6% of B), were applied. In July, when female flowers were in bloom, the following tissues were sampled: expanded leaves, androgynous catkins and female flowers. Leaves were collected again in the normal period (September) and the concentrations of macro- and micronutrients in plant tissues were determined. B content in the tissues collected in July was positively correlated with B contents in leaves sampled in September. Boron concentrations in leaves, irrespective of the sampling period, were correlated with chestnut productivity, while the other tissues did not correlate significantly. These results suggest that leaves, sampled in July, were the most efficient tissue for the early diagnosis of B deficiency

Fixação do potássio nos solos portugueses

Em Portugal, desde os anos 30 do século XX, os resultados da experimentação relativa à adubação potássica têm amiúde causado perplexidade entre os investigadores. Nos casos em que se esperariam respostas evidentes ao K, devido às suas baixas concentrações no solo, elas ou não se verificaram, ou tardaram a surgir, sobretudo no Sul do país. Neste trabalho de revisão, faz-se uma retrospectiva da experimentação realizada, na qual parece evidente a ineficácia da adubação potássica. Inventariaram-se as unidades-solo onde foram detectados indícios da fixação do K através de ensaios experimentais, bem como as unidades-solo submetidas a ensaios laboratoriais em que foi evidente a sua elevada capacidade de fixação do K. Relativamente à fixação, além da identificação dos solos fixadores de K, discutiram-se ainda os factores propícios à fixação deste nutriente, dos quais se salienta a composição mineralógica dos solos nas fracções argila, limo e areia fina. Por fim, com base nos estudos já realizados apontam-se estratégias a seguir na adubação potássica.In Portugal, since the 1930s, the results of experimentation on potassium fertilization have frequently caused perplexity among researchers. In such cases, where clear responses to K were expected due to low K concentrations in the soils, they did not occur or were very slow in manifesting themselves, particularly in the south of the country. In this review paper a retrospective of the existing experimentation was carried out where the inefficacy of K fertilization was evident. In addition, an inventory of soil types was made where evidence of K fixation had been most often detected, either through experimental trials or through laboratory tests. The laboratory data refer to the determination of soil K fixation capacity. With regard to K fixation, in addition to the identification of the K-fixing soils, the propitious factors for fixation of this nutrient are discussed, highlighting the mineralogical composition of soils in the clay, silt and fine sand fractions. Finally, based on the studies already carried out, some strategies to be followed in potassium fertilization were proposed