Características agronômicas de cultivares de milho (Zea mays L.) e qualidade dos componentes e silagem

Este trabalho foi conduzido para se avaliarem as características agronômicas (acamamento, quebramento e produtividade) e químico-bromatólogicas da matéria verde e silagem de 19 cultivares de milho. Os tratamentos foram aplicados em parcelas de 5 x 4 m em um delineamento de blocos casualizados, com quatro repetições. Por ocasião da semeadura, aplicaram-se doses correspondentes a 500 kg/ha da fórmula 4-14-8 (N-P2O5-K2O) e, aos 47 dias da emergência, 60 kg/ha de N em cobertura. Entre as dezenove cultivares estudadas, selecionaram-se, com base na porcentagem de plantas quebradas e acamadas, nove com características agronômicas adequadas para colheita mecanizada. Ao atingirem o estádio grão farináceo, as plantas de milho da área útil (12 m²) foram colhidas e passadas em picadeira, para se obterem partículas de aproximadamente 2 cm. Depois de picada e homogeneizada, aproximadamente 15 kg de matéria verde foram colocados em sacos plásticos, eliminando o ar e, em seguida, transferidos para uma câmara escura, simulando assim as condições de um silo. A produção de matéria seca dos híbridos selecionados para serem ensilados não apresentou grandes variações, destacando-se o Zeneca 850 e o Braskalb XL380 com 12,72 e 12,62 t/ha de matéria seca, respectivamente. A porcentagem de espiga nas plantas e os teores de fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), carboidratos solúveis e digestibilidade in vitro da matéria seca dos híbridos não diferiram. Contudo, os teores de FDN, FDA, N-NH3/NT e DIVMS na silagem mostraram diferenças entre os nove híbridos, o que não se verificou para proteína bruta, ácido láctico e pH

Scope and preliminary results of radiolarian biostratigraphic studies, Fort Fraser and Prince George map areas, central British Columbia

International audienceAs part of the new Nechako NATMAP project, radiolarian biostratigraphic investigations started in the Fort Fraser (93K) and Prince George (93G) map areas in central British Columbia. Their scope is to provide control on the age and structures of the Cache Creek Group and related units. Eighty samples of radiolarian chert, siliceous mudstone, and chert clasts have been collected. Preliminary chemical processing confirms radiolarians from ribbon chert strata near Fort St. James, and undated siliceous mudstone of the Sowchea sequence. Six chert pebbles from a Cretaceous conglomerate near Pinchi Lake released well preserved associations ranging in age from Middle Triassic (late Anisian-Ladinian) to Late Triassic (late Carnian, early-middle Norian, late NorianlRhaetian). Similar associations are known within the Cache Creek Group in southern British Columbia and Yukon Territory

Radiolarian biostratigraphy and implications, Cache Creek Group of Fort Fraser and Prince George map areas, central British Columbia

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Geology near Fort St. James, central British Columbia

International audienceThe Cache Creek Group rocks of the Fort St. lames area (93K) have been differentiated into Upper Paleozoic and Mesozoic suites. The Mesoloic rocks include greywacke, siltstone, argillite, limestone, and basalt tuff previously mapped as part of the Takla Group. Fine grained clastic rocks west of Stuart Lake may also be mainly of Triassic and possibly Early Jurassic age. The Cache Creek limestone (here called Mount Pope sequence limestone) is probably thrust onto Triassic ribbon cherts

Stratigraphy, structural stacking, and paleoenvironment of the Cache Creek Group, central British Columbia

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The influence of mantle plume in the genesis of the Cache Creek oceanic igneous rocks: implications for the geodynamic evolution of the inner accreted terranes of the Canadian Cordillera

International audienceWest of Prince George, British Columbia, the Cache Creek Terrane is composed of mafic lavas interlayered with both mid-Permian pelagic limestones and Upper Triassic siliceous shales and greywackes. Gabbro, basalt, dolerites, and foliated clinopyroxene-rich ultramafic rocks are exposed within the Pinchi Fault system. The mid-Permian lavas show affinities of oceanic island tholeiites. Among the Triassic lavas, three types of rocks have been distinguished. Type 1 is geochemically similar to the mid-Permian volcanic rocks. Type 2 differs from type 1 by higher TiO 2 abundances and convex rare earth element patterns. Type 3 has the highest Zr, Nb, and Ta abundances and the greatest light rare earth element enrichment. The mafic rocks within the Pinchi Fault system are similar to N-type mid-oceanridge basalt (N-MORB), and the foliated ultramafic rocks are characterized by very low trace element contents, similar to extremely depleted harzburgites. Permian lavas and Triassic type 1 and igneous rocks from the Pinchi Fault system have the highest ε Nd(i) ratios (+7.4 to +9.6) and those of type 3 alkali have the lowest ratios (+2.0 to +5.3). The ε Nd(i) values of type 2 are intermediate between those of type 1 (-+7) and type 3 (-+4.9). This suggests that the Triassic rocks generated from a heterogeneous plume source or the mixing between depleted N-MORB and enriched oceanic island basalt sources. If the mafic igneous rocks sampled in central British Columbia are representative of the preserved parts of an oceanic crust, within the Cache Creek Terrane, then that crust was dominated by oceanic plateau components, perhaps due to the difficulty of subducting thick crust.À l’ouest de Prince George, en Colombie-Britannique, le terrane de Cache Creek est composé de laves mafiques interstratifiées avec des calcaires pélagiques du Permien moyen et des schistes argileux siliceux et des grauwackes du Trias supérieur. Dans le système de failles Pinchi, on retrouve des affleurements de gabbro, de basalte, de dolérite et de roches ultramafiques foliées et riches en clinopyroxène. Les laves du Permien moyen montrent des affinités avec des tholéiites d’îles océaniques. Parmi les laves du Trias, on distingue trois types de roches. La géochimie du type 1 est similaire à celle des roches volcaniques du Permien moyen. Le type 2 diffère du type 1 par de plus hautes concentrations de TiO2 et des patrons convexes pour les éléments des terres rares. Le type 3 a les plus grandes concentrations de Zr, Nb, et Ta et le plus grand enrichissement en éléments de terres rares légers. Les roches mafiques à l’intérieur du système de failles Pinchi sont similaires aux basaltes médio-océaniques normaux (N-MORB) alors que les roches ultramafiques foliées sont caractérisées par de très faibles contenus en éléments traces, semblables à des harzburgites extrêmement appauvries. Les laves du Permien, les roches ignées et celles de type 1 du Trias provenant du système de failles Pinchi ont les rapports εNd(i) les plus élevés (+7,4 à +9,6) alors qu’ils sont les plus bas pour les roches alcalines de type 3 (+2,0 à +5,3). Les valeurs εNd(i) du type 2 sont intermédiaires entre celles du type 1 (~+7) et du type 3 (~+4,9). Cela suggère que les roches du Trias proviennent d’une source panache hétérogène ou d’un mélange entre des basaltes N-MORB appauvris et des sources enrichies de basaltes d’îles océaniques. Si les roches mafiques échantillonnées au centre de la Colombie-Britannique. sont représentatives de parties préservées d’une croûte océanique, àl’intérieur du terrane de Cache Creek, alors cette croûte a été dominée par des composantes du plateau océanique, peut-être parce qu’il eut été difficile à une croûte épaisse de passer en dessous d’une autre plaque

Biostratigraphic and biogeographic constraints on the Carboniferous to Jurassic Cache Creek Terrane in central British Columbia

International audienceConodonts, radiolarians, foramlnlferids, and corals provide essential blochronologi cal constraints on the geology and tectonics of the Cache Creek Terrane In the Nechako region, central British Columbia. Conodont collections are assigned to 20 faunas ranging in age from Bashkirian (Late Carboniferous) to Norian (Late Triassic), radiolarian collections are grouped into 5 intervals ranging from Gzhelian (Late Carboniferous) to Toarcian (Early Jurassic); 11 fusulinacean assemblages range from Bashkirian to Wordian (Middle Permian); and two coral faunas are of Bashkirian and Wordian age. These fossils collectively document a tong and relatively complete history of complex sedimentary events within the Cache Creek complex that included two major carbonate buildups in the Late Carboniferous (Pope limestone) and Middle Permian (Copley limestone); basaltic eruptions during the Bashkirian and Wordian; the onset of ocean chert sedimentation close to the Carboniferous-Permian boundary and its persistence through the Late Triassic (Sowchea succession); latest Permian and Early Triassic mixed clastics and volcanics (Kloch Lake succession); Middle and Late Triassic reworking of carbonates into breccias (Whitefish limestone) including cave-fill in older limestones (Necostle breccia); and fine-grained clastic sedimentafon persisting Into the lower Jurassic (Tezzeron succession).Tethyan, eastern Pacific and/or low latitude biogeographic attributes of the Cache Creek faunas are most notable In the Gzhelian (Upper Carboniferous fusulinaceans), Artinskian (lower Permian conodonts), Wordian (Middle Permian fusulinaceans, corals, and conodonts), and Ladinian (Middle Triassic conodonts and radiolarians)

Leaf position prevails over plant age and leaf age in reflecting resistance to late blight in potato

The effects of plant age, leaf age, and leaf position on race-nonspecific resistance against Phytophthora infestans were investigated in a series of field and controlled environment experiments with five different potato (Solanum tuberosum) cultivars. Leaf position proved to be the most significant factor; apical leaves were far more resistant to late blight than basal leaves. Plant age and leaf age had only minor effects; therefore, the resistance of a specific leaf remained about the same during its entire lifetime. The gradual increase in late blight resistance from basal leaves to apical leaves appeared to be a general effect, irrespective of cultivar, growing conditions, or resistance test. Therefore, it is important to consider leaf position in tests for late blight resistance, because contrasts in resistance may be ascribed erroneously to differences between genotypes or treatments. whereas they are actually caused by differences in leaf position

Le terrane de Slide Mountain (Cordillères canadiennes) : une lithosphère océanique marquée par des points chauds.

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