-Addition of Silicon (Si) to culture media has been shown to improve the development of seedlings grown in vitro, and to reduce losses during the acclimatization phase. The objective of this study was to evaluate the in vitro growth of Cattleya forbesii (Orchidaceae) in MS medium containing five different concentrations of SiO 2 (0.0, 0.5, 1.0, 1.5, and 2.0 g·L −1 ). At day 200, the following variables were measured: number of roots, average length of the root system, leaf area, number of leaves and shoots, shoot height, fresh and dry masses of roots and shoots, water content of roots and shoots, and pH of the culture medium. Most variables decreased as the concentration of Si increased, reducing the in vitro vegetative growth of C. forbesii. Accumulation of Si in leaf tissues was detected by scanning electron microscopy, confirming uptake by plants.The Si source and concentrations tested showed no beneficial effect on in vitro growth of C. forbesii.Keywords: Micropropagation, Culture medium, Amorphous silica. SILÍCIO NO DESENVOLVIMENTO IN VITRO DA ORQUÍDEA Cattleya forbesiiRESUMO -A adição de silício (Si) aos meios de cultura tem apontado melhor desenvolvimento das plântulas cultivadas in vitro e redução das perdas durante a fase de aclimatização. Objetivou-se avaliar cinco concentrações de SiO 2 (0,0; 0,5; 1,0; 1,5 e 2,0 g·L −1 ) em meio de cultura MS sobre o crescimento in vitro da orquídea Cattleya forbesii. Aos 200 dias, avaliou-se as variáveis: número de raízes, comprimento médio do sistema radicular, área foliar, número de folhas e de brotos, altura da parte aérea, massa fresca e seca de raízes e de parte aérea, conteúdo de água das raízes e da parte aérea, e pH final dos meios de cultura. Para a maioria das variáveis avaliadas observou-se decréscimo em função do aumento da concentração de Si, reduzindo o desenvolvimento vegetativo in vitro da C. forbesii. Além disso, detectou-se acúmulo de Si nos tecidos foliares por meio da microscopia eletrônica de varredura, confirmando a absorção deste pelas plântulas. Para o crescimento in vitro da espécie estudada, a fonte e concentrações de Si testadas, não apresentaram efeito benéfico.Palavras-chave: Micropropagação. Meio de cultura. Sílica amorfa. ________________ *

The snap bean (Phaseolus vulgaris L.) is an economically important legume worldwide due to its good nutritional quality, being considered as a source of protein, fibre, vitamins and minerals. Furthermore, snap beans present high phenolic compound levels and antioxidant activity, factors that contribute in the prevention of the oxidation effects by free radicals. Hence, the present study characterized five snap bean genotypes (UEL 1, UEL 2, UEL 405, UEL 415 and Alessa) with respect to their amino acid concentrations, total phenolic compound contents and antioxidant activities. The amino acid analysis indicated that UEL 415 showed the highest glutamic acid content (12.9 g / 100 g) and UEL 2 the highest histidine content (2.27 g / 100 g). However, only the UEL 1 genotype showed the highest total phenolic compound content (0.492 mg GAE / 100 g) and highest antioxidant activity according to DPPH• radical scavenging (64.71%). The UEL 1, UEL 2 and UEL 415 genotypes presented desirable chemical characteristics for genetic improvement programmes and their commercial exploitation by food industries.

ResumoO silício é considerado um elemento benéfico às plantas, podendo trazer incrementos na produtividade e sanidade de diversas culturas. Nos vegetais, acumula-se principalmente nas áreas de máxima transpiração. Este trabalho teve por objetivo comparar o acúmulo de silício nas folhas bandeira de diferentes genótipos de trigo (Triticum aestivum L.), com o auxílio da Microscopia Eletrônica de Varredura (MEV). O experimento foi conduzido a campo, durante o ano agrícola de 2010, aonde foram utilizados oito genótipos de trigo (cultivares BRS 208, IPR 85, BRS Pardela, BRS 210, IPR 130, CD 104, BRS 220 e a linhagem WT 07106). Aos três meses após a semeadura, retiraram-se amostras das folhas para a análise de silício em MEV e espectroscopia de energia dispersiva de raios-X (EDS). Todos os genótipos avaliados acumularam corpos silicosos em suas epidermes foliares, sendo que esses corpos apresentaram formato arredondado e deposição diferenciada entre os diversos genótipos. Palavras-chave: Silício, Triticum aestivum, corpos silicosos, microscopia eletrônica de varredura, espectroscopia de energia dispersiva de raios-X AbstractSilicon is considered a beneficial element to plants and may increase productivity and health of many crops. In plants, silicon accumulates mainly in the areas of maximum transpiration. This study aimed to investigate and compare silicon accumulation in flag leaves of different genotypes of wheat (Triticum aestivum) with the aid of scanning electron microscopy (SEM). The experiment was conducted in the field during the growing season 2010, eight wheat genotypes (BRS 208, RPI 85, BRS Pardela, BRS 210, RPI 130, CD 104, BRS 220 and WT 07106 lineage) were used. Three months after sowing, the samples were collected from the leaves to perform the silicon analysis by SEM and energy dispersive X-ray (EDS). All genotypes accumulated silica bodies in their leaf epidermis, the bodies had a rounded shape and were deposited differently from one genotype to another.

Snap beans have been widely used in organic farming as a good income source and an alternative to diversify production, with increasing use in crop rotation. This work reports the evaluation of 25 bush-type snap beans accessions for their suitability to integrate a breeding program for organic farming, as well as for their resistance to the common bacterial blight (CBB). Agronomic performance was assessed in two field experiments (September-December, 2013; April-June, 2014), in complete blocks at random, while resistance to CBB was assessed in greenhouse, in a completely randomized trial. Plants were challenged with two isolates, one from Xanthomonas axonopodis pv. phaseoli and another from X. fuscans subsp. fuscans. Accessions UEL 402, UEL 405, UEL 407, UEL 408, UEL 412, UEL 417 and UEL 420 were highly productive in both seasons (averages of 10.3, 8.7, 9.5, 9.2, 8.9, 9.3 and 9.2 t/ha, respectively), and are promising for use both as cultivars by organic farmers in the region of Londrina and also as germplasm in breeding programs for developing cultivars adapted to the region. Although all accessions were moderately susceptible to CBB, accessions UEL 407, UEL 409, UEL 411, UEL 412, UEL 424 and UEL 431 presented the lowest values for the area under CBB progress curve for both isolates.

ABSTRACT. Different plant species have different levels and locations of silicon accumulation in their tissues, and may or may not have silica bodies. Grasses usually accumulate these bodies, which may have different shapes depending on the genotype. Besides, this element can be beneficial to crops. The present study aimed to examine the forms and locations of silicon accumulation, as well as silicon content, in flag leaves of corn (Zea mays L.). This was a field experiment with two cultivars of corn: Coodetec 384 and Pioneer BG7065H. Four months after sowing, the flag leaves of the corn cultivars were obtained for determination of the silicon content of leaf tissue with the use of plasma atomic emission spectrometry, as well as examination of the different forms and locations of silicon accumulation using scanning electron microscopy and energy dispersive X-ray spectroscopy. The two cultivars were found to accumulate foliar silicon, primarily at the base of the trichomes and on the venation. Also, silica bodies in the shape of four-leaf clovers and dumbbells were detected, and the cultivar 1691 Accumulation of silicon in corn leaves ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 13 (1): 1690-1696 (2014) Coodetec 384 showed a silicon content in leaf tissue 26% higher than that of Pioneer BG7065H.