Manuel Oliveira

By Manuel Oliveira

There is evidence that temperatures all over the planet are increasing slowly but steadily. The projections for the Mediterranean basin indicate a strong warming and decreased precipitation, especially in summer, and they are not favorable for agriculture in general and, in particular, for viticulture, which is a very climate-sensitive system. The vineyards of Douro Demarcated Region, located in the northeastern Portugal, are grown in marginal conditions, and the expected daily higher temperatures and decreased rainfall are bound to affect the yield and wine quality. Touriga Nacional and Tinta Roriz are two of the most valuable varieties for high-end wines of Douro, and they were subjected to a number of experiments on mitigation techniques to counteract the worse effects of adverse weather conditions. Irrigation, canopy shading, water nebulization, and kaolin coating can mitigate the losses caused by increasing stressful conditions, but they have detrimental effects on some wine characteristics. They even might not be sufficient to protect the already producing vineyards from aggravated weather conditions.

Part of the book: Grapes and Wines

By Anabela Fernandes-Silva, Manuel Oliveira, Teresa A. Paço and Isabel Ferreira

In regions with Mediterranean climate, water is the major environmental resource that limits growth and production of plants, experiencing a long period of water scarcity during summer. Despite the fact that most plants developed morphological, anatomical, physiological, and biochemical mechanisms that allow to cope with such environments, these harsh summer conditions reduce growth, yield, and fruit quality. Irrigation is implemented to overcome such effects. Conditions of mild water deficit imposed by deficit irrigation strategies, with minimal effects on yield, are particularly suitable for such regions. Efficient irrigation strategies and scheduling techniques require the quantification of crop water requirements but also the identification of pertinent water stress indicators and their threshold. This chapter reviews the scientific information about deficit irrigation recommendations and thresholds concerning water stress indicators on peach trees, olive trees, and grapevines, as case studies.

Part of the book: Irrigation in Agroecosystems

By Manuel Oliveira and Anabela Fernandes-Silva

Yield and quality of fruits are multifaceted traits involving various plant and fruit processes that, for a given genetic makeup, depend on environmental factors and agronomic practices. Crop yield has to meet the demand of a growing population, but crop quality is a challenging issue affected by consumer’s behavior and increasingly associated with food security. The projected climate scenario for South Mediterranean Europe predicts lower precipitation and higher temperatures that will negatively affect agricultural activity. A warmer and drier climate is expected to cause changes in crop yield and its quality. Higher temperatures affect photosynthesis, causing alterations in sugars, organic acids, flavonoid contents, firmness, and antioxidant activity. Reduced soil water availability will impact on the capacity of plants to accumulate biomass and when conjugated with warmer weather, it can trigger disorders like fruit sunburn further depressing crop yields. New cultivation techniques are necessary to produce sufficient food supplies to meet the basic nutrient requirements of the growing human population and support the agriculture economy. We focus on the production of olives and wine grapes, two of the most cultivated fruit crops of Southern Europe, which is certainly strongly affected by changing weather conditions. We review the recent developments on agronomic practices to counter or minimize the projected environmental changes, and we will report on our own experiences.

Part of the book: Modern Fruit Industry

By Manuel T. Oliveira and Ana A. Oliveira

Grapevines, an economic mainstay of the Douro Demarcated Region, are under increasing stressful conditions and they can suffer further losses due to climate change. Observations on weather patterns and behavior of two autochthonous grapevines and two exotic ones were made over several years. There are indications of an increase of 2°C from 2003 to 2019 responsible for the advancement of 10 to 15 days of phenological events on all grape varieties, a clear biological sign of climate change. Against the forecasted trends, rainfall showed a trend for increasing total amount but a lower proportion during the growing season that resulted in stronger seasonality. The yields of native varieties were about 2600 kg ha−1 higher than exotic varieties, a difference supported by a larger leaf area, on average 1.7 m2 higher, and better stomatal conductance in average 2.6 mm s−1 and 2.1 mm s−1 for native and exotic varieties, respectively. These differences suggest that natives are better suited to withstand aggravated environmental conditions than the exotic. The composition of the must show significantly higher total soluble content in autochthonous grapevines but they have a lower concentration of organic acids, tannins, and polyphenols, meaning poorer organoleptic profiles.

Part of the book: Challenges in Agro-Climate and Ecosystem