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Tan spot, caused by Pyrenophora tritici-repentis, and fusarium head blight (FHB), caused by the Fusarium graminearum species complex, are among the main wheat diseases worldwide. This 3-year field study evaluated the effect of soil incorporation of calcium silicate, a source of silicon (Si), to manage tan spot and FHB and improve grain yield and quality. The effect of Si was compared on two cultivars contrasting in disease resistance and associated with one or two fungicide sprays. Calcium silicate fertilization increased the Si concentration in the soil and wheat leaf and spike tissues. The increase of Si concentration in wheat tissues was associated with reduction in the severity of both tan spot and FHB, consequently increased the quality and grain yield of wheat. The reduction of disease severity conferred by Si was greater for tan spot than FHB. The greatest control of tan spot and FHB was obtained with the moderately resistant cultivar grown in soil amended with calcium silicate (+Si) and treated with two fungicide sprayings. On the other hand, the highest grain yield, under high disease pressure, was obtained in +Si plants, regardless of the cultivar, treated with two fungicide sprays. The results of this study show for the first time that the incorporation of Si in the soil complemented the effect of genetic resistance and fungicide treatments in controlling both tan spot and FHB. Furthermore, results indicate that calcium silicate fertilization is useful as part of integrated management of these wheat diseases.

Tan spot caused by Pyrenophora tritici-repentis is a disease present in all wheat-producing countries and silicon (Si) treatment of wheat plants has been shown to increase plant resistance to tan spot. In this study, the effect of phenylpropanoid metabolism on resistance to tan spot was evaluated and some phenolic compounds that accumulated in response to P. tritici-repentis attack were identified. Furthermore, the effect of Si on phenylalanine ammonia-lyase (PAL) activity and phenolic compound accumulation were determined in situ. Antifungal activity of differentially accumulated phenolic compounds was also evaluated in in vitro tests. Results showed that the increase in concentration of phenolic compounds was greatest at the onset of infection, and that some compounds showed fungitoxic effects including fungal tip swelling, granulation of germ tube and hyphae, and hyphal hyperbranching. Silicon-induced reduction in both lesion size and tan spot disease progression were associated with activation of phenylpropanoid metabolism. PAL activity and accumulation of antifungal phenolic compounds were greater in pathogen-inoculated plants supplied with Si. In these plants, fluorescence indicative of accumulation of phenolic compounds occurred early in epidermal cells and its intensity increased during the evaluation period, showing higher numbers of fluorescent cells around infected cells. Thus, the combined responses of cell fluorescence at sites of infection, increased PAL activity and accumulation of phenols indicate that Si strengthened wheat defence responses to infection by P. tritici-repentis, reducing the severity of tan spot.

Wheat (Triticum aestivum) is an annual crop, cultivated in the winter and spring and susceptible to several pathogens, especially fungi, which are managed with fungicides. It is also one of the most consumed cereals, and can be contaminated by mycotoxins and fungicides. The objective of this study was to validate an analytical method by LC-MS for simultaneous determination of mycotoxins and fungicide residues in wheat grains susceptible to fusarium head blight treated with fungicides, and to evaluate the relationship between fungicide application and mycotoxin production. All parameters of the validated analytical method were within AOAC and ANVISA limits. Deoxynivalenol was the prevalent mycotoxin in wheat grain and epoxiconazole was the fungicide residue found in the highest concentration. All fungicidal treatments induced an increase in AFB2 production when compared to the control (without application). AFB1 and deoxynivalenol, on the contrary, were reduced in all fungicide treatments compared to the control.

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AGRONOMIA (AGRONOMY) RESUMO: O incremento de CO 2 atmosférico é uma das principais variáveis ambientais que podem afetar a produtividade das plantas cultivadas. O objetivo neste estudo foi avaliar os efeitos da elevação da concentração do CO 2 atmosférico sobre características morfofisiológicas e rendimento de grãos do trigo. Para tal, plantas de trigo da cultivar Marfim foram cultivadas sob duas concentrações de CO 2 (400 ou 700 μmol mol-1). As variáveis avaliadas foram: trocas gasosas, alterações morfológicas e componentes de rendimento de grãos. A elevação da concentração de CO 2 alterou significativamente os parâmetros de trocas gasosas, incrementou o índice de antocianina, a estatura da planta, a área foliar, a massa seca de folha e da raiz. Em relação ao rendimento, incrementou o número de grãos por espiga, o peso de mil grãos, o peso hectolitro (PH) e a produção total. Assim, a elevação da concentração de CO 2 atmosférica influência no desempenho agronômico de trigo através de alterações fisiológicas, ganho de biomassa e no incremento do rendimento de grãos. Palavras-chave: enriquecimento de CO 2 ; fotossíntese; open top chambers; rendimento de grãos; Triticum aestivum L. Morpho-physiological responses and grain yield of wheat mediated by increased atmospheric CO 2 concentration ABSTRACT: The increase in the concentration of atmospheric CO 2 is one of the main environmental variables that can affect the production of cultivated plants. The objective of this study was to evaluate the effects of increase the atmospheric CO 2 concentration on morphological and grain yield characteristics of wheat. For this, wheat plants of cultivar Marfim were cultivated under two CO 2 concentrations (400 or 700 μmol mol-1). The variables evaluated were: gas exchange, morphological alteration and grain yield components. The increases in the CO 2 concentration significantly altered the gas exchange parameters, increased anthocyanin index, plant height, leaf area, dry mass of leaves and roots. In regarding to yield, plants at 700 μmol mol-1 produced high number of grains per ear, high weight of thousand grains, high hectoliter weight (PH) and total production. Thus, the increase in atmospheric CO 2 concentration influenced the agronomic performance of wheat through physiological alteration, biomass gain and increase in the grains yield.

In the search for homogeneous planting density and satisfactory results in soybean development and yield, the treatment of seeds can be carried out using a combination of chemical fungicides, growth stimulators, and other biological agents. The objective of this study is to evaluate the effect of chemical and biological inputs for soybean seed treatment on crop development and yield. Experiments were carried out in the 2010/2011 growing season in three municipalities of Rio Grande do Sul using the following treatments: fungicide fludioxonil, Trichoderma spp., fludioxonil + Trichoderma spp., fludioxonil + Trichoderma spp. + the growth stimulator Biozyme ® , and a control (untreated). The total number of pods in treatment with Trichoderma spp. and the other treatments were up to 77% higher than that of the control. The grain yield of treatments with fludioxonil, fludioxonil + Trichoderma spp., and fludioxonil + Trichoderma spp. + Biozyme ® was up to 14% higher than that of the control. These results indicate that fludioxonil combined with the fungus Trichoderma spp. and Biozyme ® is indicated for treating soybean seeds and increases crop development and grain yield.RESUMO -Na busca por estande de plantas homogêneo e resultados satisfatórios no desenvolvimento e produção de soja, pode ser realizado o tratamento de sementes combinando fungicidas químicos, bioestimuladores e outros produtos biológicos. Dessa forma, objetivou-se avaliar a interferência de insumos químico e biológico em tratamento de sementes no desenvolvimento e produção de soja. Para isso, foram conduzidos experimentos no ano agrícola 2010/2011 em três localidades do Rio Grande do Sul, utilizando-se os seguintes tratamentos de sementes: fungicida fludioxonil; Trichoderma spp.; fludioxonil + Trichoderma spp.; fludioxonil + Trichoderma spp. + Biozyme ® ; e testemunha (sem tratamento). Para o número total de vagens, o tratamento com Trichoderma spp. e os demais tratamentos conjugados apresentaram até 77% mais vagens do que a testemunha. Os tratamentos fungicida fludioxonil, fungicida fludioxonil + Trichoderma spp. e fungicida fludioxonil + Trichoderma spp. + Biozyme ® apresentaram até 14% maior produtividade do que a testemunha. O fungicida fludioxonil foi indicado para tratamento de sementes de soja conjugado com o fungo Trichoderma spp. e o bioestimulador Biozyme ® , por promoverem o desenvolvimento de plantas e o aumento da produtividade de soja. Palavras-chave: Glycine max. Crescimento de plantas. Trichoderma spp.

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