Dinâmica de fluxo de folhas em perfilhos de capim-elefante cv. BRS Kurumi sob diferentes alturas de resíduo.

Entre as gramíneas usadas em pastagens para alimentação animal, destaca-se o capim-elefante (Pennisetum purpureum Schum.), pelo alto potencial de produção de forragem, bom valor nutritivo e facilidade de adaptação às condições climáticas predominantes em quase todo o País

Panicum maximum cv. Tanzânia: climate trends and regional pasture production in Brazil.

Projected change in forage production under a range of climate scenarios is important for the evaluation of the impacts of global climate change on pasture-based livestock production systems in Brazil. We evaluated the effects of regional climate trends on Panicum maximum cv. Tanzânia production, predicted by agro-meteorological model considering the sum of degree days and corrected by a water availa bility index. Data from Brazilian weather stations (1963?2009) were considered as the current climate (baseline), and future scenarios, based on contrasting scenarios interms of increased temperature and atmospheric CO2 concentrations (high and low increases), were determined for 2013?2040 (2025 scenario) and for 2043?2070 (2055 scenario). Predicted baseline scenarios indicated that there are regional and seasonal variations in P. maximum production related to variation intemperature and water availability during the year. Production was lower in the Northeast region and higher in the rainforest area. Total annual productionunder future climate scenarios was predicted toincrease by up to 20% for most of the Brazilian area, mainly due to temperature increase, according to each climate model and scenario evaluated. The highest increase in forage production is expected to be in the South, Southeast and Central-west areas of Brazil. In these regions, future climate scenarios will not lead to changes in the seasonal production, with largerincreases in productivity during the summer. Climate risk is expected to decrease, as the probability of occurrence of low forage productions will be lower. Due to the predicted increase in temperature and decrease in rainfall in the Northeast area, P. maximum production is expected to decrease, mainly when considering scenarios based on the PRECIS model for the 2055 scenario.

Effect of phosphorous levels during establishment of Paspalum regnellii cv. BRS Guará.

2016

Fertirrigação nitrogenada e potássica para produção de maçã cv. Julieta em clima semiárido tropical.

A cultura da macieira, a exemplo de outras frutiferas, tem na adubação mineral, um dos fatores que mais contribuem para a qualidade de frutos e produtividade (NAVA et al., 2008), sendo o nitrogênio (N) e potássio (K) os nutrientes exportados em maior quantidade pela cultura (Souza16 et al., 2013). O nitrogênio pode afetar o crescimento dos ramos em tamanho e número interferindo diretamente na produção de frutos e alterando tanto o calibre como o número de frutos produzidos (DOLINSKI et al., 2007). Outro nutriente fundamental para a macieira é o K, que constitui um dos nutrientes que mais limita a produtividade da macieira (NAVA et al., 2008) por exercer nas plantas funções relacionadas ao armazenamento de energia, eficiência do uso de água e translocação de carboidratos produzidos nas folhas (TAIZ & ZEIGER, 2013). Entretanto, as informações sobre os efeitos da adubação com N e K em macieiras cultivadas em regiões semiáridas ainda são incipientes na literatura cientifica o que motiva o presente trabalho. Neste sentido, o objetivo do presente trabalho foi avaliar os efeitos da fertirrigação nitrogenada e potássica no cultivo da macieira (cv. ?Julieta?) em Lagoa Grande-PE.

Effects and Modes od Action of Canopy Management Practices on Vine Physiology and Berry Composition in Organically-Cultivated cv. Sangiovese (Vitis Vinifera L.)

In organic and biodynamic vineyards, canopy management practices should be carefully and timely modulated, particularly in a context of climate change, for successfully achieving balanced plants, ventilated and exposed berries, elevated grape and wine quality. In 2013 and 2014, characterized by contrasting climatic conditions, the implications of post-veraison (late) or pea-size trimming, post-veraison or pre-harvest late defoliations and shoot-positioning (post-veraison) were assessed against long-shoots non treated controls, under field conditions on organically-cultivated cv. Sangiovese. The key agronomic and enological relevance of late trimming and defoliations clearly emerged in both seasons. Berry skin phenolics (e.g. anthocyanins, flavonols) increased markedly, without changes in technological parameters. In case of early trimming, such positive effects were observed only in 2013. Maintaining long shoots for shading decreased anthocyanins, flavonols and total phenolics concentrations and promoted the production of compact bunches. Experimental data strongly designated late trimming, a practice proved to contain yield and bunch compactness, as a valuable alternative to cluster thinning. Late trimming, defoliations and shoot positioning reduced the severity of Botrytis cluster rot. The highest levels of berry skins phenolic compounds in late trimmed and defoliated plants could have contributed control the severity of this pathogen. The enological benefits induced by late trimming and defoliations and shoot positioning emerged in both young and aged wines. For the first time, cell cultures from cv. Sangiovese berry tissues were obtained and enabled to investigate, in controlled conditions, the relations between mechanisms regulating secondary metabolism in grapevine cells and changes induced by environmental and agronomic factors. The Doctoral Dissertation strongly highlights the need to consider, for a proper interpretation of the multiple modifications induced by canopy management strategies, physiological mechanisms other than the canonic source-sink relationships, in particular their impact on the vine hormonal status.