*4.2.2. Peach response to water stress*

Several studies over the last decades have addressed the use of deficit irrigation, namely RDI, in peach. Ref. [31] have applied the method to peach during the phase of final swell and observed a significant production and fruit growth increase, if irrigation restrictions were applied while excessive vegetative vigor could be suppressed to favor fruit growth. Mitchell and Chalmers [32] have used RDI during the phase of fast vegetative growth, obtaining similar yield and fruit growth to a nonrestricted situation, while saving ca. 30% of irrigation water and controlling the vegetative growth. For the post-harvest phase, [129] observed that irrigation reduction decreased pruning requirements and increased flowering in the next season. For the same phase, and also during fruit development, [130] saved 40% of irrigation water with light implications in production and fruit size. More recently, the benefits of applying

**Figure 1.** Phenological phases of peach (*Prunus persica*).

RDI during stage II of fruit development have also been stated [89], including beneficial reduction of tree vigor and improvement of fruit quality [71]. De la Rosa et al. [131] applied RDI after harvest, concluding that it was beneficial to control vegetative growth. Results from [70] also confirm the positive effects of RDI to control vegetative growth without a significant effect in fruit production. However, these authors recommend caution in long-term (over 3 years) application of RDI, since it gradually reduces canopy, what can affect fruit yield. The same effect was observed by [132, 133], and these last authors even advise the discontinuing of RDI after 3 years. A prevalent long-term plant adaptive response over an immediate causal effect of RDI in a single season is therefore foreseen. **Table 1** presents an overview of the most common practices for RDI in peach referred in literature. RDI has been mostly applied in the phase of late fruit development or after harvesting, and in general, the most reported effects refer to a decrease in vegetative vigor, production and fruit size, but an increase in fruit quality and water use efficiency.

Thus, for peach, considering the available information on the use of RDI, production is not significantly affected as long as applied in an adequate phase and bearing in mind, the variety relative precocity. Other advantages can be pointed out such as an easier management of the crop (if the vegetative vigor is restrained) and an increased efficiency in the use of water resources. Precaution is advised concerning long-term cumulative effects in production, as sometimes a negative influence has been observed.

PRD strategies for peach have showed contradictory results as sometimes a positive effect has been observed in yield, in comparison with other conventional DI practices [43], but other studies advocate no agronomic advantages in such technique, especially if the increased installation costs are considered [137].

#### *4.2.3. Effect on fruits quality*

Studies addressing the effect of deficit irrigation on peach fruit quality either refer to an improvement of it [71] or no effect [134, 136].

**RDI**

**Reference**

Mitchell and Chalmers [32]

Johnson et al. [129]

Girona et al. [130] Bellvert et al. [89]

Lopez et al. [71]

De la Rosa et al. [131]

Girona et al. [70]

Naor et al. [39] Marsal et al. [133] Marsal et al. [133] Marsal et al. [133] Pascual et al. [134] Pascual et al. [134]

Zhou et al. [135] Zhang et al. [136] Abrisqueta et al. (2010)

**Table 1.**

SWP, midday stem water potential; ETc, crop evapotranspiration (not stressed); FI, full irrigation.

Deficit irrigation practices applied to peach—application phases and effects referred in literature.

**Dormant bud**

**Bud swell**

**Pink stage**

**Early bloom**

**Full bloom**

**Late bloom**

**Petal fall**

**Fruit set**

**Split-jacket**

**Small fruitlets**

**Pit hardening**

**Fruit veraison**

**Commercial** 

**Physiological** 

**ripening**

**ripening**

**<** **<** **<** **</=**

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**<** **<** **<**

> **<**

**<** **<**

**=** **<**

> **<**

> **<**

> **<**

> **>**

25% ETc

65

**=/< =**

25% ETc

http://dx.doi.org/10.5772/intechopen.80365

**>**

**>**

**>**

75% ETc SDI

**<**

70% ETc

**<**

**=**

30% ETc

SWP >−1.8,

−2.02 MPa

SWP >−1.5 MPa

Deficit Irrigation in Mediterranean Fruit Trees and Grapevines: Water Stress Indicators and Crop…

80% ETc

**<**

SWP −2.0 MPa

**</= >**

15% ETc

60% FI

35% ETc

**>**

50% ETc

**=**

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<30%

Several

<40%

**Tree vigor**

**Production**

**Fruit size**

**WUE**

**water/**

**Fruit quality**

**Irrigation** 

**restrictions**

**Final swell**

**Phase**

**RDI effects**

RDI during stage II of fruit development have also been stated [89], including beneficial reduction of tree vigor and improvement of fruit quality [71]. De la Rosa et al. [131] applied RDI after harvest, concluding that it was beneficial to control vegetative growth. Results from [70] also confirm the positive effects of RDI to control vegetative growth without a significant effect in fruit production. However, these authors recommend caution in long-term (over 3 years) application of RDI, since it gradually reduces canopy, what can affect fruit yield. The same effect was observed by [132, 133], and these last authors even advise the discontinuing of RDI after 3 years. A prevalent long-term plant adaptive response over an immediate causal effect of RDI in a single season is therefore foreseen. **Table 1** presents an overview of the most common practices for RDI in peach referred in literature. RDI has been mostly applied in the phase of late fruit development or after harvesting, and in general, the most reported effects refer to a decrease in vegetative vigor, production and fruit size, but an increase in fruit qual-

Thus, for peach, considering the available information on the use of RDI, production is not significantly affected as long as applied in an adequate phase and bearing in mind, the variety relative precocity. Other advantages can be pointed out such as an easier management of the crop (if the vegetative vigor is restrained) and an increased efficiency in the use of water resources. Precaution is advised concerning long-term cumulative effects in production, as

PRD strategies for peach have showed contradictory results as sometimes a positive effect has been observed in yield, in comparison with other conventional DI practices [43], but other studies advocate no agronomic advantages in such technique, especially if the increased

Studies addressing the effect of deficit irrigation on peach fruit quality either refer to an

ity and water use efficiency.

**Figure 1.** Phenological phases of peach (*Prunus persica*).

64 Irrigation in Agroecosystems

sometimes a negative influence has been observed.

installation costs are considered [137].

improvement of it [71] or no effect [134, 136].

*4.2.3. Effect on fruits quality*

Deficit Irrigation in Mediterranean Fruit Trees and Grapevines: Water Stress Indicators and Crop… http://dx.doi.org/10.5772/intechopen.80365 65 Pérez-Sarmiento et al. [138] applying several RDI strategies to apricot have found improvements in some qualitative characteristics of the fruits, such as the level of soluble solids, sugar/ acid ratio, and fruit color, without negative effects in yield. Along with these characteristics, fruit firmness was also improved in a study conducted by Zhou et al. [135] when applying an SDI strategy with a light water stress. Therefore, from these studies, it can be concluded that the use of deficit irrigation in peach doesnot seem to induce negative effects in the fruit quality parameters referred above. Nevertheless, several authors refer the occurrence of double fruits or fruit cracking, if severe water stress is imposed. For example, Naor et al. [39] refer this occurrence for values of stem water potential lower than −2.0 MPa. This suggests that, in what concerns fruit quality, there is an identifiable limit to the application of deficit irrigation, as discussed in Section 4.

a critical stage for grapevines. Given the actual trend in climatic change, the grapevines will advance their phenological stages, shorten the growing season with maturation occurring under hotter and drier conditions [150], a phenomenon already observed in the viticultural

Deficit Irrigation in Mediterranean Fruit Trees and Grapevines: Water Stress Indicators and Crop…

http://dx.doi.org/10.5772/intechopen.80365

67

The wine grower has to manage irrigation for the benefit of yield and quality that maximizes the returns as the growers profits are a combination of both yield and quality, and a very low

It is well documented that irrigated grapevines increased significantly their yield per plant over rainfed plants. The increased yield is due to larger berries that diluted color, aroma, and

Imposing very high levels of water stress must be avoided because it results in declining vine

In viticultural regions where water stress can cause damages to the production objectives, DI strategy is a management tool that can ensure a balance between vegetative and reproductive development while maintaining yields and improving fruit composition [42] but the irrigation timing and amount must be adjusted to the local environment (*terroir*) and to wine typicity to avoid potential negative impacts [154]. Too small quantity of irrigation water can be an expensive procedure with no beneficial effect while too much water might induce an excessive vegetative growth, increase berry size, and reduce the concentration of important

Nevertheless, simultaneous events of high temperatures, drought and elevated evapotranspiration have detrimental effects on yield and berry composition as the plant carbon assimilation is much reduced due to lower photosynthetic activity compounded by loss of leaf area [156]. It is well documented that water stress decreases leaf stomatal conductance, leaf water potential, vegetative growth, leaf to fruit ratio, berry size and their fresh and dry weights, and

Water stress and temperature have a complex relationship. Higher temperatures can enhance both sugar accumulation and organic acid decay, but acidity is more affected than sugar levels, then, for the same sugar level, grapes grown under warmer conditions have lower acidity [157]. This decoupling has been reported for other metabolites, such as anthocyanins [141], proanthocyanidins [158], and aromas [159]. The decoupling of anthocyanins and sugars, in favor of anthocyanins, was observed in Cabernet Sauvignon under increasing water stress [160]. During the ripening period, if elevated temperature and drought occur simultaneously, the effects on the decoupling of anthocyanins and sugars can be felt only slightly due to the contrasting responses to these two factors, and in fact, restricted water supply during berry development can partially restore anthocyanin/sugar ratios disrupted by high temperature [161]. In "Red Tempranillo," elevated temperature and drought reduced total polyphenol index, malic acid and increased color density, but did not modify anthocyanin

soluble solids, and correspond to a lower quality of the must and hence the wine.

capacity and productivity, eventually becoming economically unsustainable [153].

region of Alto Douro, Portugal [151].

*4.3.2. Grapevines response to water stress*

metabolites for quality wines [155].

yield [46, 141].

concentration [119].

yield, no matter what quality might not be profitable [152].

Most of the studies addressing water use efficiency (WUE) in peach under deficit irrigation report an increase in comparison to full irrigation practices, although with lower yields for moderate or severe water stress [135].

#### **4.3. Grapevines**

#### *4.3.1. Vegetative growth and production cycle*

Grapevines (*Vitis vinifera* L.) develop over a number of periodic events, phenological stages, mentioned in the literature as budbreak, flowering and veraison [139]. Budbreak signals the beginning of the vine seasonal growth and physiological activity after a period of dormancy during the coldest months of the year but its starting date is neither influenced by winter temperature or precipitation [140, 141]. However, a recent report [142] mentions that waterstressed grapevines delay the onset of bud dormancy, reduce the cold exposure required for releasing buds from dormancy, and hasten budbreak. Flowering initiates the reproductive cycle and is followed by the fruit setting. At veraison, the ripening process is initiated when important must, and later wine, quality attributes develop. The time needed to reach berry maturity is related to temperature and precipitation and it is shortened as the temperature rises and precipitation decreases [141]. Grapevine phenology is strongly influenced by weather and climate [143] and the duration of each stage is largely determined by temperature [144]. Moreover, ambient temperature conditions the plant physiology, imparts the berry composition, and ultimately, the wine quality [145].

The climates with best potentials for quality wines are those with mild and wet winters, warm springs, and hot and dry summers. These climatic characteristics are common for the so-called Mediterranean climate well-known for its dry summer, and grapevines are well adapted to water scarcity because of its extensive, deep roots, and mechanisms of drought resistance such as tight control of stomatal aperture [146] and osmotic adjustment [147].

The cultivation of grapevines, fruit in Europe is mainly used for winemaking, is a climatesensitive agricultural system and it expected a rise in average temperatures worldwide by 2050, some regions might be over the optimum range of temperature for the growing season [148]. Precipitation in many viticultural areas is expected to decrease substantially in the period between budbreaking and veraison [149] resulting in more intense water stress during a critical stage for grapevines. Given the actual trend in climatic change, the grapevines will advance their phenological stages, shorten the growing season with maturation occurring under hotter and drier conditions [150], a phenomenon already observed in the viticultural region of Alto Douro, Portugal [151].
