Efeito do aumento da concentração de CO2 atmosférico sobre a incidência de Pyricularia grisea em sementes de arroz cultivado em estufas de topo aberto

Resumo: O trabalho avaliou o efeito do aumento do CO2 do ar sobre a incidência de Pyricularia grizea em sementes de arroz da variedade Shao Tiao Tsao. O experimento foi conduzido em estufas de topo aberto (OTC), com os tratamentos: cultivo em OTC sem injeção de CO2 (Est); OTC com injeção de CO2 aplicando-se de 100 a 300 ?mol/mol CO2 acima da concentração atmosférica atual (Est+CO2); e sem OTC e sem injeção de CO2 (Test). Avaliou-se a incidência do patógeno nas sementes por meio do teste do papel filtro com congelamento, peso de sementes por panícula e peso de 100 sementes por tratamento. A incidência de brusone nas sementes de arroz foi 11,3% e 8,3% para os tratamentos Est e Est+CO2, respectivamente, diferindo estatisticamente em relação à testemunha, com incidência de 0,8%. Os pesos de sementes por panícula e de 100 sementes foram negativamente correlacionados com a incidência da doença nas sementes

Convex algebraic geometry of curvature operators

We study the structure of the set of algebraic curvature operators satisfying a sectional curvature bound under the light of the emerging field of Convex Algebraic Geometry. More precisely, we determine in which dimensions $n$ this convex semialgebraic set is a spectrahedron or a spectrahedral shadow; in particular, for $n\geq5$, these give new counter-examples to the Helton--Nie Conjecture. Moreover, efficient algorithms are provided if $n=4$ to test membership in such a set. For $n\geq5$, algorithms using semidefinite programming are obtained from hierarchies of inner approximations by spectrahedral shadows and outer relaxations by spectrahedra

Bioprospecting for plant and fungus extracts with systemic effect to control the cucumber powdery mildew.

This work was aimed to select plant and fungus extracts showing systemic effect to control the cucumber powdery mildew. For that, ethanolic extracts were obtained from five basidiomycetes and 71 plant species and tested under greenhouse conditions. Cucumber plants cv. 'Safira' were sprayed with extracts at the first true leaf growth stage and inoculated with Sphaerotheca fuliginea at the second leaf growth stage. The number, diameter and sporulation rate of powdery mildew colonies were evaluated 6 days after inoculation. In an initial screening phase, the extracts of the following plants and fungi revealed some systemic effect against the powdery mildew: Aloe vera (aloe), Bidens pilosa, Ganoderma sp. (basidiomycete), Hyptis crenata, Mascagania betbamiana, Ocotea suaveolens, Oudemansiella canarii (basidiomycete), Pinus taeda (pine), Riehardia grandiflora and Vernonia polyanthes. They were compared in three other experiments and those from Oudemansiella, Ganoderma, pine needles and aloe leaves were the most efficient reducing the number of colonies on the secondary leaf by 79, 65, 30 and 21 %, respectively. Extracts from fruiting bodies of Oudemansiella and Ganoderma also decreased the diameter of colonies by 20 % as well as the sporulation rate by 45 and 70 %, respectively. While Ganoderma did not show any direct effect in vitro, the extract of Oudemansiella (60 mg fresh weight ml[-1]) reduced the germination of powdery mildew conidia at 48 h after inoculation by 71 %. Furthermore, Oudemansiella-extract strongly inhibited the mycelium growth of Cladosporium oxysporum in liquid medium. The possible modes of action of these extracts are discussed

Zoneamento de riscos climáticos para a semeadura do Capim-Marandu em municípios do estado de São Paulo.

O Estado de São Paulo possui cerca de 7 milhões de hectares de pastagens, dos quais quase 60% são pastos plantados (IBGE, 2008). Levantamento realizado pela Secretaria de Agricultura e Abastecimento do Estado de São Paulo mostra que 89% das pastagens do estado são formadas por braquiárias (SÃO PAULO, 2010). No último censo agropecuário, 8% da área de pastagens plantadas no Estado de São Paulo foram consideradas degradadas pelos produtores (IBGE, 2008).bitstream/item/42523/1/Documentos101.pd