No abstract

Two cultivars of Vitis vinifera L., namely Grenache and Shiraz, have been described as having near‐isohydric and near‐anisohydric responses respectively to soil water stress (Schultz, Plant Cell and Environment, 26, 1393–1405, 2003). Given that contrast in sensitivity to soil water, a question arises as to whether atmospheric moisture stress will elicit similar differences. The present study was undertaken to investigate this issue by comparing stomatal responses in these same two cultivars to contrasting vapour pressure deficit (VPD). Test material included field grape vines in the Barossa Valley and pot‐grown vines under partial shade in Adelaide. Our experiments showed that the same isohydric/anisohydric distinction as described by Schultz (2003) is apparent in leaf responses to atmospheric moisture stress. In the more isohydric cultivar, Grenache, stomatal conductance is more responsive to changes in VPD. This heightened sensitivity (compared with Shiraz) appears to be associated with higher levels of abscisic acid (ABA) in Grenache xylem sap. Expression studies on the key genes in the ABA biosynthetic pathway indicate that regulation of the V.v.nced1 gene expression in leaf tissue, but not in the root tissues, is associated with the changes in the xylem sap ABA. Moreover, the two cultivars (Grenache and Shiraz) differed with respect to both scale and time course of those responses. We conclude that these two Vitis vinifera cultivars do indeed differ significantly in the way that they respond to potentially stressful atmospheric conditions, and that ABA physiology is a key process in these contrasting responses. An understanding of such mechanisms, including the relative importance of roots and shoots in determining vine response to abiotic stress, is highly relevant to irrigation scheduling, and to management of associated variation in vineyard productivity across diverse environments.

The effects of transient water deficits on berry growth on field-grown grapevines were examined over four consecutive seasons. Varying deficits were achieved by withholding irrigation during four periods of berry development after flowering of Vitis vinifera cv. Shiraz. Water deficit during the period after flowering resulted in the greatest reduction in berry weight compared with that of well-watered vines especially in years with high temperature summation. In contrast, water deficit after veraison had only a minor effect on berry weight at maturity and berries were insensitive to water deficit during the month before harvest. In each of the four seasons, which were climatically diverse, berry growth exhibited a normal double-sigmoid development but with a distinct decline in weight before harvest. The onset of the loss in weight was coincident in all treatments in each year and was not related to the season, the degree of water deficit or to berry size. These findings have implications for yield prediction and for the chemical composition of the crop. Transient water deficit and berry growth

No abstract

Regulated Déficit Irrigation (RDI) and Partial Rootzone Drying (PRD) are examples of stratégie irri¬ gation management. They have been successfully adopted for winegrape production in Australia with the aim of controlling végétative growth to produce 'balanced' vines, and to improve both water-use efficiency (measured as tonnes of fruit per ML of irrigation water applied) and fruit quality for winemaking. This paper will outline some of the physiological principles that underpin these stratégies and pro vide détails of expérimental and commercial experience in Australian vineyards. Résumé : La RDI ('Regulated Déficit Iirrigation' ; Irrigation déficitaire contrôlée) et le PRD ('Partial Rootzone Drying' ; assèchement partiel des racines) sont des exemples de gestion des stratégies d'irrigation. Celles-ci ont été adoptées avec succès pour la production de raisins de cuve en Australie, dans le but de contrôler la croissance végé¬ tative pour produire des vignes'équilibrées' et d'améliorer l'efficacité de la gestion de l'eau (mesurée en tonnes de fruit par ML d'eau d'irrigation) ainsi que la qualité du fruit pour l'élaboration du vin. Cet article met en évidence certains des principes physiologiques sous-jacents à ces stratégies, et fournit des indications détaillées sur des études menées à titre expérimental et commercial dans des vignobles australiens.

Thaumatin-like proteins and chitinases, which are pathogenesis-related (PR) proteins, were the major soluble protein components of grapes from five cultivars of Vitis vinifera. This dominance of PR proteins was apparent at berry softening (véraison) and then throughout berry development for the Muscat of Alexandria, Sultana, and Shiraz cultivars and in the berries of the Sauvignon Blanc and Pinot Noir cultivars examined at commercial maturity. The M(r) of the major thaumatin-like protein from Muscat of Alexandria grapes was 21 272, and those of the three major chitinases from this cultivar, ChitB, ChitC, and ChitD, were 25 588, 25 410, and 25 457, respectively. The vines in the study were irrigated and showed no obvious signs of disease. Shiraz vines that had not been irrigated throughout the season were clearly water stressed, but had levels of PR proteins in the berry similar to vines that had been fully irrigated. It appears that the production of PR proteins that cause protein instability in wines by grapes may be little influenced by environmental conditions.

Municipal and winery wastewater can provide a valuable irrigation source in regions where water accessibility is problematic or sustainable disposal of waste is essential. It is imperative, however, that when used for irrigation, water conservation benefits are not compromised by a decline in soil and plant health. To date, published literature investigating the use of wastewaters for grapevine production is restricted to a limited set of studies. Globally, wastewater usage within the horticultural sector, including winegrape production, is increasing. It is necessary, therefore, to better understand the short-and long-term implications of such practice. Although wastewaters may contain a range of organic and inorganic pollutants, this review focuses primarily on specific issues associated with high salt loading that is typical under wastewater irrigation. Managing salt, in particular sodium (Na + ) and potassium (K + ), in wastewater will be necessary in order to maintain the soil physical, chemical and biological health in the long term. Soil structural degradation resulting from a high concentration of exchangeable monovalent cations is of major concern where wastewater is being used for irrigation. This review will address (i) the effect of wastewater irrigation on vine performance and grape quality; (ii) chemical and physical changes in soils irrigated with municipal and winery wastewater; and (iii) management practices that may assist in ameliorating vineyard soils abundant in monovalent cations as a result of wastewater irrigation. AbbreviationsCEC cation exchange capacity; EPP exchangeable potassium percentage; ESP exchangeable sodium percentage; PAR potassium adsorption ratio; SAR Sodium adsorption ratio. Laurenson et al. Use of recycled wastewater

No abstract