Terroir 2010 banner
IVES 9 IVES Conference Series 9 Diurnal cycles of grapevine leaf water potential under field conditions

Diurnal cycles of grapevine leaf water potential under field conditions

Abstract

[English version below]

Les cycles journaliers du potentiel hydrique foliaire (Ψl) ont été établis toutes les heures, pour différents stades phénologiques, sur deux localités et en fonction de différentes mesures de la température de l’air et du déficit en pression de vapeur (VPD). De faibles valeurs pour ces 2 paramètres ont été enregistrées tout au long de la saison à l’endroit le plus frais. Les mesures du potentiel hydrique foliaire obtenues au stade floraison montrent que les vignes de Sauvignon blanc à l’endroit le plus frais, ont subi un stress hydrique plus important au cours de la journée par rapport aux vignes situées à l’endroit plus chaud. De plus le potentiel hydrique du sol (Ψm) obtenu sur les sols bien drainés de la localité plus fraîche, à ce même stade, était d’environ -0.03 MPa comparés au -0.01 MPa de la localité plus chaude. Ceci laisse à penser que le statut hydrique de la vigne durant la journée est d’abord contrôlé par la teneur en eau du sol. Les différences de statut hydrique entre les deux endroits diminuent progressivement durant la phase de croissance végétative et ce, jusqu’à la période suivant les vendanges durant laquelle le potentiel foliaire obtenu à l’endroit plus frais devenait supérieur à celui obtenu à l’endroit plus chaud. Les valeurs relativement faibles du potentiel hydrique obtenues à l’aube à l’endroit plus frais, indiquent que les vignes étaient exposées à un important stress hydrique comme le montre la faible teneur en eau du sol (Ψm= -0.77 MPa). La fermeture stomatique partielle observée sur les vignes de l’endroit plus frais, ont permis d’éviter de trop sévères stress hydriques (Ψl < -1.2 MPa) durant les plus chaudes heures de la journée. Cependant ce mécanisme de résistance fut à peine observé à l’endroit plus chaud.
On peut donc conclure sur ces résultats, qu’un faible potentiel hydrique obtenu à l’aube, ne conduira pas forcément à un stress hydrique plus important durant les plus chaudes heures de la journée, et vice versa. La détermination des cycles hydriques journaliers, ainsi que le stress hydrique observés sur une journée entière à différents stades phénologiques sont donc indispensables si l’on veut comprendre et quantifier l’effet du terroir sur le statut hydrique de la vigne.

Diurnal cycles of leaf water potential (Ψl) were established on an hourly basis at various phenological stages at two localities with different air temperature and vapour pressure deficit (VPD). Lower air temperature and VPD values were recorded consistently throughout the season at the cooler locality. Leaf water potential measurements at flowering showed that Sauvignon blanc grapevines at this cooler locality were subjected to a higher degree of water stress throughout the day compared to grapevines at the warmer locality. At this phenological stage, soil water matric potential (Ψm) of the well-drained soil at the cooler locality was ca -0.03 MPa compared to ca -0.01 MPa at the warmer locality. This suggested that diurnal grapevine water status was primarily controlled by soil water content. The difference in grapevine water status between the two localities gradually diminished as the growth season progressed until the post harvest period when Ψl in grapevines at the cooler locality tended to be higher compared to those at the warmer one. The relatively low pre-dawn Ψl at the cooler locality during this measurement cycle indicated that the grapevines were exposed to excessive water stress as a result of the low soil water content (i.e. Ψm = -0.77 MPa). Partial stomatal closure in grapevines at the cooler locality, however, prevented excessive water stress (i.e. Ψl < -1.2 MPa) during the warmest part of the day compared to grapevines at the warmer terroir where almost no stomatal control occurred.
It appears from these results that low pre-dawn Ψl values do not necessarily imply that grapevines will experience more water stress during the warmest part of the day, or vice versa. Hence, determination of daily water status cycles, as well as the accumulated water stress over the full diurnal cycle at various phenological stages is invaluable in order to understand and quantify terroir effects on grapevine water status.

DOI:

Publication date: January 12, 2022

Issue: Terroir 2004

Type: Article

Authors

M. Laker (1), P.A. Myburgh (1) and E. Archer (2)

(1) ARC Infruitec-Nietvoorbij, Private Bag X5026, 7599 Stellenbosch, Republic of South Africa
(2) LUSAN Premium Wines, Private Bag 104, 7599 Stellenbosch, Republic of South Africa

Contact the author

Keywords

Soil water matric potential, diurnal cycles, leaf water potential, accumulated water stress

Tags

IVES Conference Series | Terroir 2004

Citation

Related articles…

Effect of regulated deficit irrigation regime on amino acids content of Monastrell (Vitis vinifera L.) grapes

Irrigation is an important practice to influence vine quality, especially in Mediterranean regions, characterized by hot summers and severe droughts during the growing season. This study focused on deficit irrigation regime influence on amino acids composition of Monastrell grapevines under semiarid conditions (Albacete, Southeastern of Spain). In 2019, two treatments were applied: non-irrigation (NI) and regulated deficit irrigation (RDI), watered at 30% of the estimated crop evapotranspiration from fruit set to onset of veraison. Grape amino acids content was analyzed by HPLC. Berries from non-irrigated vines showed higher concentration of several amino acids, such as tryptophan (73%), arginine (70%), lysine (36%), isoleucine (27%), and leucine (21%), compared to RDI grapes. Arginine is, together with ammonium ion, the principal nitrogen source for yeasts during the alcoholic fermentation; while isoleucine, tryptophan, and leucine are precursors of fermentative volatile compounds, key compounds for wine quality. Moreover, NI treatment increased in a 14% the total amino acids content in grapes compared to RDI treatment. The reported effects might be because yield was 70% higher in RDI vines than in the NI ones and, therefore, the sink demand was increased in the irrigated vines. In addition, NI vines suffered more severe water stress and it is known that the amino acids synthesis and accumulation can be influenced by the plant response to stress. According to the results, the irrigation regime showed effect on amino acids concentration in Monastrell grapes under semiarid conditions. Grapes from non-irrigated vines showed a higher content of several amino acids relevant to the fermentative process and to the wine aroma compounds formation. It is demonstrated that the final content of nitrogen-related components in grapes is influenced by the irrigation regime. The convenience of the irrigation strategy to suggest will depend on the desired wine style and the target yield levels.

Climate, Viticulture, and Wine … my how things have changed!

The planet is warmer than at any time in our recorded past and increasing greenhouse emissions and persistence in the climate system means that continued warming is highly likely. Climate change has already altered the basic framework of growing grapes for wine production worldwide and will likely continue to do so for years to come. The wine sector can continue to play an important role in leading the agricultural sector in addressing climate change. From developing on…

Impact of climate change on the viticultural climate of the Protected Designation of Origin “Jumilla” (SE Spain)

Protected Designation of Origin “Jumilla” (PDO Jumilla) is located in the Spanish provinces of Albacete and Murcia, in the South-eastern part of the Iberian Peninsula, where most of the models predict a severe impact of climate change in next decades. PDO Jumilla covers an area of 247,054 hectares, of which more than 22,000 hectares

The rootstock, the neglected player in the scion transpiration even during the night

Water is the main limiting factor for yield in viticulture. Improving drought adaptation in viticulture will be an increasingly important issue under climate change. Genetic variability of water deficit responses in grapevine partly results from the rootstocks, making them an attractive and relevant mean to achieve adaptation without changing the scion genotype. The objective of this work was to characterize the rootstock effect on the diurnal regulation of scion transpiration. A large panel of 55 commercial genotypes were grafted onto Cabernet Sauvignon. Three biological repetitions per genotype were analyzed. Potted plants were phenotyped on a greenhouse balance platform capable of assessing real-time water use and maintaining a targeted water deficit intensity. After a 10 days well-watered baseline period, an increasing water deficit was applied for 10 days, followed by a stable water deficit stress for 7 days. Pruning weight, root and aerial dry weight and transpiration were recorded and the experiment was repeated during two years. Transpiration efficiency (ratio between aerial biomass and transpiration) was calculated and δ13C was measured in leaves for the baseline and stable water deficit periods. A large genetic variability was observed within the panel. The rootstock had a significant impact on nocturnal transpiration which was also strongly and positively correlated with maximum daytime transpiration. The correlations with growth and water use efficiency related traits will be discussed. Transpiration data were also related with VPD and soil water content demonstrating the influence of environmental conditions on transpiration. These results highlighted the role of the rootstock in modulating water deficit responses and give insights for rootstock breeding programs aimed at identifying drought tolerant rootstocks. It was also helpful to better define the mechanisms on which the drought tolerance in grapevine rootstocks is based on.

Local adaptation tools to ensure the viticultural sustainability in a changing climate

[lwp_divi_breadcrumbs home_text="IVES" use_before_icon="on" before_icon="||divi||400" module_id="publication-ariane" _builder_version="4.19.4" _module_preset="default" module_text_align="center" module_font_size="16px" text_orientation="center"...