RESUMO A seleção de genótipos de couve mais resistentes à desidratação é importante, pois além de ser comercializada in natura, é bastante perecível. Para o estudo pós-colheita o ajuste de modelos de regressão é útil. Porém quando se tem muitos tratamentos torna-se difícil a identificação dos superiores por meio da representação gráfica das curvas. Neste sentido, o teste identidade de modelos agrupa as curvas estabelecendo genótipos que possuem comportamento estatisticamente semelhante. Assim, objetivou-se selecionar acessos de couve quanto à desidratação pós-colheita utilizando o teste de identidade de modelos e avaliar sua eficiência. Avaliou-se a perda acumulada de matéria fresca de 22 genótipos de couve, sendo 19 do banco de germoplasma da UFVJM e três cultivares comerciais (COM). Utilizou-se o teste de identidade de modelos para o agrupamento estatístico das curvas de regressão. Os acessos UFVJM-19 e UFVJM-32 obtiveram menores taxas de desidratação em função do tempo. O teste facilitou a interpretação dos resultados, com redução de 22 para seis curvas de regressão, auxiliando a seleção dos melhores genótipos. Os acessos UFVJM-19 e UFVJM-32 são os mais indicados por apresentarem menor desidratação pós-colheita, sendo os mais recomendados para a comercialização in natura.

ABSTRACT The selection of kale genotypes more resistant to dehydration is important, since this product is marketed fresh and characterized as perishable. For the post-harvest study, the adjustment of regression models is useful. However, when there are many treatments, it is difficult to identify the superior one through the graphical representation of the curves. In this sense, the model identity test groups the curves establishing genotypes that have statistically similar behavior. Thus, we aimed to select kale accesses for post-harvest dehydration using the model identity test. The accumulated loss of fresh matter of 22 kale genotypaes was evaluated, being 19 of the germplasm bank of the UFVJM and three commercial cultivars (COM). The model identity test was used for the statistical grouping of the regression curves. The UFVJM-19 and UFVJM-32 accessions had lower rates of dehydration as a function of time. The test facilitated the interpretation of the results, with a reduction of 22 to six regression curves, helping to select the best genotypes. The UFVJM-19 and UFVJM-32 accessions are the most indicated because they present lower post-harvest dehydration, being the most recommended for commercialization.

RESUMO O objetivo deste trabalho foi caracterizar o crescimento da planta e determinar a melhor época de colheita da batata-doce, considerando raízes e parte aérea (ramas). O trabalho foi realizado no campus JK da Universidade Federal dos Vales do Jequitinhonha e Mucuri, em Diamantina-MG. O delineamento experimental foi blocos ao acaso, com quatro repetições. Foram realizadas doze coletas consecutivas de três plantas centrais da parcela, em intervalos de quinze dias. As plantas foram fracionadas em raiz, caule e folhas para a determinação das suas respectivas massas secas. A área foliar também foi mensurada e foram calculados os índices de crescimento. Os dados obtidos foram analisados por meio de regressão. Entre 75 e 156 dias após o transplantio (DAT), ocorreu o maior acúmulo de massa seca pela planta, caracterizando a fase de maior crescimento. Para maior rendimento de ramas, as plantas devem ser colhidas entre 60 e 87 DAT; para maior rendimento de raízes, a colheita deve ser realizada 180 DAT. O período de 80 a 118 DAT foi o mais adequado para a colheita simultânea de raízes e ramas, obtendo-se as maiores produtividades para ambos. Logo, a época ideal de colheita na batata-doce depende da sua finalidade de uso e de índices fisiológicos associados aos objetivos do cultivo.

ABSTRACT This research was installed to study plant growth of sweet potato and identify the most favorable harvest time for both roots and the aboveground part (stems). The experiment was carried out at the JK campus of the Federal University of the Vale do Jequitinhonha e Mucuri, in Diamantina, MG, complete blocks at random, with four replications. Three plants in the central part of the experimental plots were collected in twelve consecutive harvests at 15-day intervals. Plants were fractionated in roots, stems, and leaves to determine the dry matter of each part. Leaf area was also measured and growth rates were calculated. Data were analyzed by means of regression. Plants reached the highest dry matter accumulation between 75 and 156 days after transplanting (DAT), which corresponded to the phase of greatest growth. Plants should be harvested between 60 and 87 DAT to achieve the highest stem yield. For the highest root yield, the harvest should be carried out 180 DAT. The period from 80 to 118 DAT was the most adequate for reaching simultaneously the highest yields for both roots and stems. Therefore, the ideal harvest time for sweet potatoes depends on the use intended for the plant and on the physiological indexes associated with it.

Abstract Herbicides can impact non-target metabolic pathways in natural enemies and lead to the reduction of these populations in the field. Behavioral characteristics, morphology and histology of reproductive structures and reproduction of females of Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae) were evaluated under the effect of the herbicides atrazine, nicosulfuron and the mixture of both. The number of mature oocytes per ovary was lower in females exposed to the herbicides atrazine, nicosulfuron and the mixture of both. Herbicides did not affect the longevity and mortality of P. nigrispinus, therefore, they are selective for this predator. On the other hand, herbicides can cause sublethal effects by affecting the reproduction of predators.

ABSTRACT The aim of this work was to determine the persistence of auxinic herbicides applied on tropical pasture and toxicity for succeeding crops. The herbicides were applied in an area of dystrophic red‒yellow latosol with pasture infested of weeds. At 40, 80, and 280 days after application of herbicide, the soil samples were collected at depths of 0 to 20 cm. Soil with residues of 2,4-D, 2,4-D + picloram, triclopyr, and a soil without herbicide application were analyzed with six replicates. Seven crops were cultivated in these soils: cucumber (Cucumis sativus L.), velvet bean [Mucuna pruriens (L.) DC.], pigeon pea [Cajanus cajan (L.) Millsp.], alfalfa (Medicago sativa L.), lablab bean [Lablab purpureus (L.) Sweet], corn (Zea mays L.), and sorghum [Sorghum bicolor (L.) Moench]. The plants of cucumber, pigeon pea, and alfalfa were the most susceptible to the auxinic herbicide residues. However, the lablab bean was the only one among the dicot evaluated that showed tolerance to the 2,4-D + picloram residual when cultivated in soils at 280 days after application of herbicide. Corn and sorghum showed lower chlorophyll content in soils with 2,4-D + picloram residual up to 80 days after application of herbicide.

Intercropping is a common practice among farmers in tropical regions of the world and has persisted for years, not only for traditional reasons, but also for certain advantages that helped in its ecological adaptation. In regard to low income farmers with small areas for cultivation, more attention should be given to the cost of production and better land management. Thus, the aim of this work was to determine the best intercropping system of cassava with other crops. The experiment was conducted in an area belonging to the cassava (Manihot esculenta) producers of the Planalto de Minas district in Diamantina, Minas Gerais State, Brazil. The treatments comprised cassava intercropped with maize, beans and dwarf pigeon pea, as well as controls with and without weeding. The dry mass of shoots for maize, beans and dwarf-pigeon pea was affected by the presence of cassava. The productivity of cassava was dependent on cultivar and the intercropped crop. The highest harvest indexes were observed when cassava was intercropped with maize. In a general way, intercropping with maize and beans showed the highest area equivalence indexes and are recommended for the cassava crop.

Intercalar cultivos es una práctica común entre los agricultores de las regiones tropicales del mundo, que ha persistido a lo largo de los años, no sólo por tradición, sino también por la búsqueda de las ventajas que han ayudado en su adaptación ecológica.Cuando se considera a agricultores con pequeñas propiedades de cultivo y bajos ingresos económicos, se debe poner más atención en los costos de producción y en el mejor aprovechamiento de la tierra. Así pues, el objetivo de este trabajo fue determinar el mejor sistema de intercalar la yuca con otros cultivos. El experimento se realizó en un área perteneciente a los productores de yuca (Manihot esculenta) del distrito de Planalto de Minas en Diamantina, Minas Gerais, Brasil. Los tratamientos consistieron en intercalar la yuca con maíz, frijoles y guisantes enano paloma, así como los controles con y sin deshierbe. La producción de materia seca de rebrote de maíz, frijoles y guisantes enano paloma se vio afectada por la presencia de yuca. La productividad de la yuca depende de la variedad utilizada y de los cultivos intercalados. Los mayores índices de cosecha se observaron cuando la yuca se intercaló con maíz. De forma general se puede afirmar que el cultivo de la yuca, intercalado con maíz y frijol, muestra los índices de equivalencia área más altos, siendo el más recomendado para el cultivo de la yuca.

Competition between weeds and crops results in a lower availability of some resources to crop species, which causes deficiencies, such as water and nutritional deficiencies and low light quality or quantity. The aims of this study were to evaluate the effects of Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster, cv. Xaraes (brachiaria) emergence times comparing with corn (Zea mays L.), in addition to the fertilization and application of different nicosulfuron and atrazine herbicides levels, on the physiological characteristics of intercropped species. The physiological characteristics Brachiaria plants that were treated with herbicides were negatively affected. The emergence time of Brachiaria plants in comparison with corn altered the physiological characteristics of both. The Brachiaria plants that emerged before corn presented higher photosynthetic and transpiration rates and reduced the intensity of these characteristics in corn. Thus, the Brachiaria plants that emerged before the corn crop presented a higher physiological efficiency, and they were more competitive than the weeds that emerged during other seasons.

O cultivo de Crambe abyssinica é recente no Brasil, existindo carência de informações sobre a sua gestão no que concerne à obtenção de elevada produtividade com o mínimo de risco económico e ambiental. O objetivo deste trabalho consistiu em avaliar o efeito dos herbicidas aplicados em doses crescentes, nas características fisiológicas de crambe. Os ensaios foram conduzidos em blocos casualizados com quatro repetições, no arranjo fatorial 5x4+1, onde o fator A representou cinco herbicidas e o fator B as doses testadas, além de uma testemunha sem aplicação. Foram avaliados os seguintes herbicidas e doses: fluazifope-p-butilo 0,25; 0,75; 1,0 e 1,5 L ha-1; cletodime 0,1; 0,3; 0,4 e 0,6 L ha-1; bentazona+imazamoxi 0,25; 0,75; 1,0 e 1,5 L ha-1; s-metolacloro 0,38; 1,13; 1,5 e 2,25 L ha-1; e setoxidime 0,25; 0,75; 1,0 e 1,5 L ha-1. As plantas de crambe apresentaram respostas diferenciadas à aplicação dos herbicidas. Todas as substâncias activas estudadas causa-ram efeitos negativos nas características fisiológicas da cultura; a mistura bentazona+imazamoxi promoveu a morte das plantas na dose de rótulo. Os herbicidas fluazifope-p-butilo, s-metolacloro e setoxidime provocaram redução drástica na taxa fotossintética nas maiores doses, e a eficiência no uso da água foi afetada por todos os herbicidas testados.

The cultivation of Crambe abyssinica is relatively recent in Brazil, and crop management data aiming to high yields with minimal economic and environmental risk is scarce. We aimed with this study to evaluate the effect of herbicides at varying doses on physiological traits. The experiment was installed in completely randomized blocks design with four replications, in factorial scheme 5x4+1, being factor A the five herbicides and factor B its doses, plus a control treatment with no herbicide. The following herbicides and doses were tested: fluazifop-p-butyl 0,25; 0,75; 1,0 e 1,5 L ha-1; clethodim 0,1; 0,3; 0,4 e 0,6 L ha-1; bentazon+imazamox 0,25; 0,75; 1,0 e 1,5 L ha-1; s-metolachlor 0,38; 1,13; 1,5 e 2,25 L ha-1; and sethoxydim 0,25; 0,75; 1,0 e 1,5 L ha-1. Crop plants presented differential behaviour to herbicides, causing all crop injuries at some degree; bentazon+imazamox promoted plant death at the label dose. Fluazifop-p-butyl, s-metolachlor and sethoxydim promoted great reductions in photosynthesis rate at the highest doses; on the other hand, water use efficiency was reduced by all herbicides.

Desenvolveu-se uma técnica de detecção rápida de Ceratocystis fimbriata em lenho de eucalipto (Eucalyptus spp.) infetado, visualizando-se clamidósporos (aleuroconídios) ao microscópio ótico comum, em vasos do xilema, medula e raios medulares, a partir de cortes histopatológicos à mão livre, feitos com lâmina de barbear, ao microscópio estereoscópico. O tempo médio gasto para a detecção do patógeno, do corte histopatológico tangencial à total visualização dos clamidósporos ao microscópio ótico comum, foi de 3,5 min e bem menos utilizando-se corte longitudinal passando pela medula, contra, no mínimo, quatro a cinco dias, usando-se outras técnicas como o isolamento em BDA, deposição de fragmentos de lenho doente entre fatias de cenoura usadas como isca, ou pedaços de lenhos doentes deixados em câmara úmida. Essa técnica histopatológica é também viável para a detecção do patógeno em outros hospedeiros lenhosos e, inclusive, para a detecção de hifas de Lasiodiplodia theobromae, mesmo quando esses dois fungos estavam num mesmo tecido, como na doença-complexo seca de mangueira investigada no Sultanato de Omã. Além de eucalipto, mangueira (Mangifera indica) e cacaueiro (Theobroma cacao) é provável que essa técnica possa ser estendida para outros hospedeiros lenhosos de C. fimbriata.

A quick histopathological technique was developed to detect clamidospores (aleuroconidia) of Ceratocystis fimbriata in infected xylem vessels and medulla of eucalyptus (Eucalyptus spp.) wood using light microscopy, and tangential hand prepared cross sections made with razor blade under a stereoscopic microscope. The average time necessary to detect the pathogen, including sample preparation and microscope observations, was 3.5 min and less when longitudinal sections passing by the medulla were made. Therefore, this method was significantly quicker than other traditional techniques such as pathogen isolation on potato-dextrose-agar medium, deposition of infected wood fragments between slices of carrot bait, or placing the infected pieces of wood in a moist chamber. This technique also was viable to detect C. fimbriata colonizing other woody hosts such as cocoa (Theobroma cacao), mango (Mangifera indica), and hyphae of Lasiodiplodia theobromae even when both organisms were in the same tissue as investigated in the mango blight disease in the Sultanate of Oman.