**1. Introduction**

Fruit production is a major agricultural activity all over the world. In 2016 the global production was above 33 × 106 metric tons and occupied about 5.6 × 106 hectares [1]. According to a survey in 2013, 1.55 million holdings in the European Union (UE) managed fruit orchards, and in 2015 3.2 million hectares were dedicated to fruit growing that represented more than 28 × 106 euros in 2018 [2]. In 2017, the world area under vines rose to 7534 kha, and grape production reached 73 million tons most of it for wine production estimated at 279 million hectoliters in 2018 [3]. Europe is a leading producer of wine grapes with 3.2 million hectares under vines

worth of almost 22 billion euros of wine exports [2]. In 2018, the global production of table olives was estimated in 1.8 × 106 tons (EU 0.9 × 106 ) and 3.1 × 106 tons of olive oil (EU 2.2 × 106 ), representing a trade value of 2.8 × 106 euros for olive oil (EU 2.1 million euros) [2]. These figures render the importance of fruit production on a global scale that is likely to increase in the near future in tandem with larger demand for food, fiber, and fuel as a result of growing population, change in dietary preferences, and bioenergy policies [4]. The food demand driven by a larger and more affluent population challenges the agricultural systems to increase the output with reduced external inputs and minimal environmental impacts [5, 6] all under more difficult environmental conditions given the forecasts of an increased temperatures and more irregular rainfalls that negatively affect agriculture [7], and the Southern Europe will be strongly affected where yield losses and impaired product quality are expected [8, 9].

#### **2. Abiotic stresses: temperature and water availability**

Average temperature is expected to rise somewhere between 1.5 and 4°C from pre-industrial time until the end of the century [7]. Temperature increase affects photosynthesis, causing changes in concentration of sugars and organic acids, flavonoid contents, fruit firmness, and antioxidant activity [10].

Some unripe fruits with green skin can photosynthesize, but the fruits are primarily a sink of photosynthetic products with origin in the leaves. The temperature of the leaves follows approximately the air temperature, and net photosynthesis increases with temperature up to a certain limit that is species dependent, but in general at values greater than 35°C, there is a reduction of photosynthetic activity [11]. Temperature has strong influence on leaf water potential (ψl), stomatal conductance (gs), and intercellular CO2 concentration [12]. Rising temperatures increase the water loss from the leaves, and their water potential becomes more negative to a point the stomata start closing reducing stomatal conductance and the flow of intercellular CO2 that further impairs photosynthesis [13]. High temperature also diminishes starch and sucrose synthesis, by reduced activity of sucrose phosphate synthase, ADP-glucose pyrophosphorylase, and invertase [14]. Heat stress can reduce the total leaf area of the plants and trigger earlier leaf senescence that have a negative impact on the total photosynthesis performance [12]. Prolonged periods of low photosynthetic activity deplete reserves of carbohydrates, and plants might starve [15].

Soluble sugars (sucrose, glucose, and fructose) and organic acids (tartaric, malic, and citric acids) are major osmotic compounds that accumulate in fleshy fruits [15]. The biosynthesis of these compounds is related to photosynthesis that uses light (solar radiation) as source of energy, and it has been shown that the photosynthetic rate is positively correlated with light intensity till a saturation point is reached depending on the plant species and on temperature [12]. Increased light intensity also raises the temperature, and, above a critical level, protein and enzymes are broken, photosynthetic tissue is killed, cells might die, and fruits are sunburnt, all resulting in yield loss and low-quality produce [16].

At molecular level, temperature influences the protein structure, and the activity of cellular proteins becomes less stable under high and low temperatures indirectly affecting the activity of transmembrane transporters necessary to import assimilates and nutrients and to accumulate sugars and polyphenols in the fruit for the completion of the maturation process [17].

Fruits and vegetables contain different antioxidant compounds such as vitamin C, vitamin E, carotenoids, and polyphenol compounds. Among the polyphenols,

**47**

*Vineyard and Olive Orchard Management to Maintain Yield and Quality Under Abiotic Stress…*

flavonoids (flavanols, flavonols, and anthocyanins) are largely present in plants, and their content is partially responsible for antioxidant activity. Temperature is the most significant factor affecting antioxidant activity in vegetables and fruits, and, as temperature raises, the enzyme reactions are accelerated, antioxidant activity is

Stressful conditions related to high temperatures are coupled with water availability that can mitigate or aggravate the effects of temperature. The increase in water demand when temperature rises is driven by plant transpiration necessary just to keep their canopies cool by water evaporation. Thus, water demand will increase at the same time as rainfall is scarcer and irregular in its frequency; therefore, an efficient use of water is particularly important for agriculture, which is the major sector for the use of freshwater resources and whose economic viability is dependent on water availability. Water uptake from the soil brings mineral nutrients that are circulated together with organic nutrients through the vascular tissues of the plant as water circulates throughout the plant. Water retention determines cell turgor, drives plant cell expansion, and permits many plant functions such as stomatal movements and transpiration [19]. Water is the abiotic factor that exerts a major effect on growth and productivity of agricultural crops, and increasingly frequent periods of drought, particularly in the Mediterranean region, is expected

Moderate drought reduces yields but can have a beneficial effect in fruit quality via two major mechanisms: (a) reduction in leaf stomatal conductance that results in a decrease in net photosynthesis and (b) exacerbation of oxidative stress/ oxidative signaling. Net photosynthesis is responsible for primary metabolites that are the major source of precursors for the biosynthesis of phenolic compounds, carotenoids, and ascorbate. Oxidative stress may trigger the biosynthetic pathways of these compounds [21, 22]. The balance between productivity and quality benefits from a certain level of water deficit, but it depends upon the intensity, duration, and repetition of events of water deficit [23]. Water deficits during the vegetative growth stages difficult canopy development, flowering and fruit setting, and the accumulation of carbon compounds. On other hand, deficits occurring during the maturation of fruits show positive impacts on soluble sugar accumulation and enhancement of fruit aroma. The level of stress that benefits the entire cycle of the plant is likely to be depend, simultaneously, on species and environmental conditions, but when a certain threshold of water stress is surpassed, the beneficial

The fruit quality is a composition of physicochemical properties and the perception of the consumer allowing for a definition of quality that discriminates between natural characteristics of the fruit and those dictated by socioeconomic and marketing factors [25, 26]. The quality of grapes (*Vitis vinifera* L.) for winemaking is evaluated on characteristics imparted to the final product, and as such their quality is referred to the berry composition, in particular, to the content of sugars, organic acids, amino acids, phenolics, and aroma precursors that are function of genotypic,

After fruit setting, the berry pericarp and the seeds augment in volume rapidly; organic acids, mostly malic, tartaric, and citric, accumulate in the mesocarp cell vacuoles. At the end of this period, growth slows down, and the seed maturation is completed. The maturation phase initiates at veraison, when berries of red varieties accumulate anthocyanins (red pigments) in the exocarp, glucose and fructose

*DOI: http://dx.doi.org/10.5772/intechopen.85954*

augmented, and existing antioxidants decline [18].

to be the most adverse among the abiotic factors [20].

effects are no longer observed [23, 24].

environmental, and agronomic factors [25, 27].

**3. Wine grape quality**

#### *Vineyard and Olive Orchard Management to Maintain Yield and Quality Under Abiotic Stress… DOI: http://dx.doi.org/10.5772/intechopen.85954*

flavonoids (flavanols, flavonols, and anthocyanins) are largely present in plants, and their content is partially responsible for antioxidant activity. Temperature is the most significant factor affecting antioxidant activity in vegetables and fruits, and, as temperature raises, the enzyme reactions are accelerated, antioxidant activity is augmented, and existing antioxidants decline [18].

Stressful conditions related to high temperatures are coupled with water availability that can mitigate or aggravate the effects of temperature. The increase in water demand when temperature rises is driven by plant transpiration necessary just to keep their canopies cool by water evaporation. Thus, water demand will increase at the same time as rainfall is scarcer and irregular in its frequency; therefore, an efficient use of water is particularly important for agriculture, which is the major sector for the use of freshwater resources and whose economic viability is dependent on water availability. Water uptake from the soil brings mineral nutrients that are circulated together with organic nutrients through the vascular tissues of the plant as water circulates throughout the plant. Water retention determines cell turgor, drives plant cell expansion, and permits many plant functions such as stomatal movements and transpiration [19]. Water is the abiotic factor that exerts a major effect on growth and productivity of agricultural crops, and increasingly frequent periods of drought, particularly in the Mediterranean region, is expected to be the most adverse among the abiotic factors [20].

Moderate drought reduces yields but can have a beneficial effect in fruit quality via two major mechanisms: (a) reduction in leaf stomatal conductance that results in a decrease in net photosynthesis and (b) exacerbation of oxidative stress/ oxidative signaling. Net photosynthesis is responsible for primary metabolites that are the major source of precursors for the biosynthesis of phenolic compounds, carotenoids, and ascorbate. Oxidative stress may trigger the biosynthetic pathways of these compounds [21, 22]. The balance between productivity and quality benefits from a certain level of water deficit, but it depends upon the intensity, duration, and repetition of events of water deficit [23]. Water deficits during the vegetative growth stages difficult canopy development, flowering and fruit setting, and the accumulation of carbon compounds. On other hand, deficits occurring during the maturation of fruits show positive impacts on soluble sugar accumulation and enhancement of fruit aroma. The level of stress that benefits the entire cycle of the plant is likely to be depend, simultaneously, on species and environmental conditions, but when a certain threshold of water stress is surpassed, the beneficial effects are no longer observed [23, 24].
