Corn root morphoanatomy at different development stages and yield under water stress.

The objective of this work was to characterize the morphoanatomy of roots and the yield traits of two corn hybrids contrasting for drought tolerance (DKB 390, tolerant; and BRS 1030, sensitive), at different stages of development. Water deficit was imposed for ten days, in a greenhouse, at three growth stages: V5, VT, and R3. These treatments were combined to generate cumulative stress during the plant cycle, as: V5VT, V5R3, VTR3, and V5VTR3. The following were analyzed: root anatomy; proportion of aerenchyma in the cortex; metaxylem number and diameter; phloem thickness; as well as morphological characteristics, such as root length, volume, and surface area, specific root length, length of fine roots, grain yield, and ear length and diameter. Development stage affected the responses to stress: DKB 390 showed the best performance for root morphoanatomy and yield traits, under drought stress, at the reproductive stages, mainly R3, and in the treatments with cumulative stress, especially V5VTR3; whereas BRS 1030 presented higher means for the studied parameters, mainly at the V5 and VT stages, but did not show a higher grain yield under water stress. The greater tolerance of the DKB 390 hybrid to water deficit is probably linked with a memory of pre?exposure to water stress at different growth stages

Teores de fenólicos em raizes de milho sob toxidez de alumínio.

Os mecanismos de tolerância ao Al propostos na literatura podem ser classificados em mecanismos de exclusão e mecanismos de tolerância interna. Os mecanismos de exclusão previnem o Al de atravessar a membrana plasmática e penetrar no simplasto. Os mecanismos de tolerância interna imobilizam, compartimentalizam ou detoxificam o Al que penetrou no simplasto. Tem sido sugerido que compostos fenólicos atuam em ambos os mecanismos, devido à sua capacidade de complexar metais como o alumínio e também por agirem como um forte antioxidante em resposta a estresses abióticos. O objetivo deste trabalho foi identificar diferenças no teor de ácidos fenólicos solúveis totais e de ácidos fenólicos (ácido ferúlico, 5-5?diferúlico e para-cumárico), ligados à parede celular de raízes de milho entre linhagens contrastantes quanto à tolerância ao alumínio, Cateto 237 (tolerante) e L53 (sensível), quando expostos à toxidez desse elemento. As plântulas foram cultivadas em solução nutritiva completa, na ausência (período de 0 h) e na presença de Al (AlK(SO4)2), na atividade de 39 mM (períodos de 12, 24, 48 e 72 h). Fenólicos solúveis totais foram analisados pelo método Azul da Prússia, enquanto os fenólicos liberados da parede celular foram analisados através de Cromatografia Líquida de Alta Eficiência. Os resultados obtidos sugerem que os fenólicos possam ter participação nos mecanismos de tolerância ao alumínio em milho, considerando-se que a linhagem Cateto 237-tolerante foi capaz de manter a concentração de fenólicos solúveis totais e aumentou as concentrações dos ácidos p-cumárico, ferúlico e 5-5?diferúlico, na parede celular, sob toxidez de Al

Detecção e caracterização da bactéria Pantoea ananatis associada à doença mancha branca em milho, sorgo e capim-colchão.

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Evolução do rebanho ovino entre 2007 e 2016.

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Polymer/layered silicate nanocomposite as matrix for bioinsecticide formulation.

Due to current encouragement to the use of bioinsecticides for pest control and the susceptibility of biological agents to external factors, we investigated the use of a polymer nanocomposite (PLN, polymer/ layered silicate nanocomposite) as matrix to encapsulate an entomopathogenic fungus active against pest insects of palm trees. The beads were formed by extrusion and the following variables were assessed: fungus conidial concentration (series 1: 107; series 2: 108 and series 3:109 conidia/mL) and nanolayered silicate concentration (0; 0.5; 1; 2 and 4%). The matrix was evaluated by X-ray powder diffraction and Fourier transform infrared spectroscopy and the following characteristics of the products were assessed: percent of encapsulated conidia, size distribution and polydispersity index, swelling index, formulation?s in vitro ability to release conidia and stability under different storage temperatures. PLN, whose interactions could be visualized by FTIR, proved to be a potential matrix for this fungus, because, while composed by natural substances non-toxic to the environment, it succeeded to encapsulate high amounts of conidia (series 2). A barrier effect with bentonite increase was also demonstrated by increased fungus germination time and thermal stability

Genomic prediction applied to high-biomass sorghum for bioenergy production.

The increasing cost of energy and finite oil and gas reserves have created a need to develop alternative fuels from renewable sources. Due to its abiotic stress tolerance and annual cultivation, high-biomass sorghum (Sorghum bicolor L. Moench) shows potential as a bioenergy crop. Genomic selection is a useful tool for accelerating genetic gains and could restructure plant breeding programs by enabling early selection and reducing breeding cycle duration. This work aimed at predicting breeding values via genomic selection models for 200 sorghum genotypes comprising landrace accessions and breeding lines from biomass and saccharine groups. These genotypes were divided into two sub-panels, according to breeding purpose. We evaluated the following phenotypic biomass traits: days to flowering, plant height, fresh and dry matter yield, and fiber, cellulose, hemicellulose, and lignin proportions. Genotyping by sequencing yielded more than 258,000 single-nucleotide polymorphism markers, which revealed population structure between subpanels. We then fitted and compared genomic selection models BayesA, BayesB, BayesC?, BayesLasso, Bayes Ridge Regression and random regression best linear unbiased predictor. The resulting predictive abilities varied little between the different models, but substantially between traits. Different scenarios of prediction showed the potential of using genomic selection results between sub-panels and years, although the genotype by environment interaction negatively affected accuracies. Functional enrichment analyses performed with the marker-predicted effects suggested several interesting associations, with potential for revealing biological processes relevant to the studied quantitative traits. This work shows that genomic selection can be successfully applied in biomass sorghum breeding programs