Article

Grapevine under deficit irrigation: hints from physiological and molecular data. Ann Bot

Instituto Superior de Agronomia, Technical University of Lisbon, Tapada da Ajuda 1349-017 Lisbon, Portugal.
Annals of Botany (Impact Factor: 3.3). 03/2010; 105(5):661-76. DOI: 10.1093/aob/mcq030
Source: PubMed

ABSTRACT BACKGROUND: A large proportion of vineyards are located in regions with seasonal drought (e.g. Mediterranean-type climates) where soil and atmospheric water deficits, together with high temperatures, exert large constraints on yield and quality. The increasing demand for vineyard irrigation requires an improvement in the efficiency of water use. Deficit irrigation has emerged as a potential strategy to allow crops to withstand mild water stress with little or no decreases of yield, and potentially a positive impact on fruit quality. Understanding the physiological and molecular bases of grapevine responses to mild to moderate water deficits is fundamental to optimize deficit irrigation management and identify the most suitable varieties to those conditions. SCOPE: How the whole plant acclimatizes to water scarcity and how short- and long-distance chemical and hydraulic signals intervene are reviewed. Chemical compounds synthesized in drying roots are shown to act as long-distance signals inducing leaf stomatal closure and/or restricting leaf growth. This explains why some plants endure soil drying without significant changes in shoot water status. The control of plant water potential by stomatal aperture via feed-forward mechanisms is associated with 'isohydric' behaviour in contrast to 'anysohydric' behaviour in which lower plant water potentials are attained. This review discusses differences in this respect between grapevines varieties and experimental conditions. Mild water deficits also exert direct and/or indirect (via the light environment around grape clusters) effects on berry development and composition; a higher content of skin-based constituents (e.g. tannins and anthocyanins) has generally being reported. Regulation under water deficit of genes and proteins of the various metabolic pathways responsible for berry composition and therefore wine quality are reviewed.

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    • "The vine water status is another factor influencing composition of grapes and plant response. It is related to the leaf area of the system and to the atmospheric supply and demand [4] [18] [19] [20]. A gradual and moderate water deficit, imposed before veraison, boosts the buildup of sugar and anthocyanins, diminishes acidity, regulates vegetative and fruit growth and canopy microclimate. "
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    DESCRIPTION: Abstract Temperature and plant water status are considered determinant for physiological processes and grape composition, and plant architecture contributes in a significant way in their regulation. The aim of this study was to evaluate the effects of micro-thermal conditions and water supply on the evolution and composition of berries on Merlot cultivar, influenced by plant architecture. The experiment was carried out in a commercial vineyard, in 2002 and 2003 with cv Merlot. The following parameters were measured in plants trellised to Vertical Shoot Positioning (VSP) and lyre: characterization of plant architecture (Point Quadrat), thermal conditions (canopy and air temperatures), water supply (pre-dawn leaf water potential), berry weight, and berry evolution and composition (sugar content, total acidity and pH and anthocyanins). Samples were taken weekly from veraison to harvest with two replicates. Quantity and evolution of berry compounds depended on plant architecture, and this affected the microclimate and the water status of plants. Lyre showed higher yields and higher sugars and anthocyanins values. Acidity was higher in VSP. The maximal temperature of the canopy was higher than the environmental maximal temperature, as well as the thermal amplitude. VSP registered thermal peaks and a broader thermal amplitude, whereas lyre showed more hours within the thermal ranges favorable to photosynthesis and anthocyanins synthesis. The greater leaf surface of the lyre caused water deficit situations.
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    • "leaf transpiration through stomata, reducing water loss from the plant tissues, and thereby avoiding severe plant dehydration or the total or partial embolism in the xylem vessels (Chaves et al., 2010). Because of this, there is a decline in CO 2 fixation declines, and therefore so does the photosynthetic activity of the plant (Chaves et al., 2007). "
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    ABSTRACT: Water deficit is the most limiting factor for yield and fruit-quality parameters in papaya crop (Carica papaya L.), deficit-irrigation (DI) strategies offering a feasible alternative to manage limiting waterresources. When DI is applied, it is crucial to assess the physiological status of the crop in order to main-tain the plant within a threshold value of water stress so as no to affect yield or fruit-quality parameters.The aim of this work was to evaluate the feasibility of thermal imaging in young papaya plants to assessthe physiological status of this crop when it is subjected to different DI regimes, studying the relation-ships between the changes in leaf temperature (Tleaf) and in the major physiological parameters (i.e.,stomatal conductance to water vapor, gs; transpiration, E; and net photosynthesis, An). The trial was con-ducted in a greenhouse from March to April of 2012. Plants were grown in pots and subjected to fourirrigation treatments: (1) a full irrigation treatment (control), maintained at field capacity; (2) a partialroot-zone drying treatment, irrigated with 50% of the total water applied to control to only one side ofroots, alternating the sides every 7 days; (3) a regulated deficit irrigation (50% of the control, applied toboth sides of plant); (4) and a non-irrigated treatment, in which irrigation was withheld from both sidesof the split root for 14 days, followed by full irrigation until the end of the study. Significant relationshipswere found between Tleafand major physiological variables such as gs, E and An. Additionally, significantrelationships were found between the difference of leaf-to-air temperature (�Tleaf–air) and gas-exchangemeasurements, which were used to establish the optimum range of �Tleaf–airas a preliminary step to thecrop-water monitoring and irrigation scheduling in papaya, using thermal imaging as the main sourceof information. According to the results, we conclude that thermal imaging is a promising technique tomonitor the physiological status of papaya during drought conditions.
    Agricultural Water Management 08/2015; DOI:10.1016/j.agwat.2015.07.017 · 2.33 Impact Factor
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    • "grape quality while allowing for a small drop in yield ( Chaves et al . , 2010 ) ."
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    ABSTRACT: Vine water status is widely considered to be fundamental to grape yield and quality. Typical Mediterranean vineyards experience seasonal droughts so water deficits need to be controlled. We evaluated the usefulness and effectiveness of a field spectroradiometer used to estimate vine water content at the leaf and canopy levels. The experiment was conducted in four commercial vineyards located in the Bierzo region (northwestern Spain) on four different grape varieties (Mencía, Cabernet Sauvignon, Tempranillo and Merlot). Data on spectral measurements and leaf variables (total specific leaf fresh weight, equivalent water thickness and specific leaf weight) were compiled during the growth phase up to berry set and veraison in 2009 and 2012 and the relationship between leaf variables, vegetation indices and continuum removal variables was studied. The results varied depending on the variety; also, at canopy level they were not suitable for determining water content. Equivalent water thickness and total specific leaf fresh weight for Tempranillo and Mencía were related to the normalized difference infrared and shortwave infrared water stress indices. Using the continuum removal variables, the best correlations for equivalent water thickness were achieved for band area and maximum band depth calculated for the 1200 nm, 1450 nm and 1950 nm intervals. To estimate vine water status, we recommend calculating the band area for 1450 nm because of its link to equivalent water thickness (R2 = 0.681 for Tempranillo). We demonstrate that yield spectroradiometry is a rapid and non-destructive method for estimating leaf water content in commercial vineyard at leaf level.
    Agricultural Water Management 07/2015; 156. DOI:10.1016/j.agwat.2015.03.024 · 2.33 Impact Factor
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