GiESCO 2015 – Session 1: Ecophysiology, water, irrigation

By monitoring plant water use continuously, new irrigation techniques can be implemented to promote more efficient vineyard water use. In order to demonstrate the impact of a new plant-based irrigation method in terms of water savings and vineyard performances, we designed an experiment across multiple vineyards in contrasted climatic condition during a very dry season.

In the last few decades the trend of increasing global temperatures has affected the accumulation of sugars in berries and hence the alcohol degree of wines. Numerous studies have considered different agronomic practices that limit photosynthetic activity and therefore the accumulation of sugars in the berry.

A better understanding of grapevine responses to drought and high air temperatures can help to optimize vineyard management to improve water use efficiency, yield and berry quality. Faster and robust field phenotyping tools are needed in modern precision viticulture, in particular in dry and hot regions such as the Mediterranean. Canopy temperature (Tc) is commonly used to monitor water stress in plants/crops and to characterize stomatal physiology in different woody species including Vitis vinifera.

In California, surface water is a public trust resource that is used by competing interests including urban, agriculture, fish and wild life and other needs. We evaluated vineyard water use on a landscape scale in two watersheds in a climate where 95% of precipitation occurs between November and May. The Upper Russian River Watershed has two large on-stream reservoirs that enable regulated water flow year round.

Radiation is one of the main environmental variables that determine leaf microclimate within the vine, and consequently its photosynthesis and carbohydrate metabolism. The objective of this study was to comprehend the relationships among photosynthetic performance, carbohydrate metabolism, and related gene expression of grapevine leaves grown under different radiation regimes.

Nowadays, treated wastewater is considered in a lot of countries as a growing alternative resource of water. Although the wastewater reuse remains currently a very limited practice in France, its development in region like Languedoc-Roussillon submitted to high water stress appears to be essential to secure and make sustainable regional agriculture such as viticulture.

Abstract
Grapevine flowers development and fruit set are both influenced by cold nights in the vineyard. In this study, impact of chilling temperatures (0°C overnight) on carbon metabolism was investigated in the inflorescences of two cultivars, Pinot noir (PN) and Gewurztraminer (GW), selected according to their distinct sensitivity to the “coulure” process, GW being the most sensitive.

Drought-induced changes in vessel size and distribution and shoot hydraulic conductivity were investigated in field-grown Syrah grapevines (Vitis vinifera L.) in Northern Greece. Three irrigation regimes, replicated four times, were applied from berry set through harvest: full irrigation (FI: 100% of crop evapotranspiration), deficit irrigation (DI: 30% of crop evapotranspiration) and non-irrigated (NI).

Drought poses the most important environmental constraint to plant survival and crop productivity. Therefore, the goal of this study is to advance a more holistic understanding of drought resistance by examining the ecophysiological and morpho-anatomical adjustments of different cultivars subjected to drought conditions.

Climate change will particularly affect temperature and precipitation regimes in Alpine areas. Mountain viticulture will therefore experience new threats for its economical and environmental sustainability. Under such modified climatic conditions, there is a need to enhance the use efficiency of the irrigation water.

Water regime is a major controllable factor in determining grape and wine quality in the vineyard. However, the effects of water conditions on grape phenolic composition are often contrasting depending on the severity of water restriction. In addition, the effect of water regime on tannin polymerization has not been extensively studied.

The combined effects of radiation and water supply on leaf water potential, stomatal conductance and petiole hydraulic conductance (kpetiole) of field-grown grapevines (Vitis vinifera L. cv. Chasselas) were studied during 2013 growing season at the Agroscope Research Station in Leytron (Switzerland).

In vascular plants, water is transported in a metastable form below its vapor pressure in xylem tissue. Under high tensions (negative pressures), the stability of the water column can be broken by the irruption of air bubbles in the xylem, a phenomenon called cavitation.

It has long been believed that ripening grape berries become dependent upon phloem water supply because xylem flow into the berries ceases at veraison due to rupture of vessels during rapid berry expansion. We provide evidence that this hydraulic isolation dogma should be replaced by a new model.

According to the latest forecasts of climate change, water will become scarcer in the near future, especially in Mediterranean areas. Increasing water scarcity would force viticulture to make changes in the use of cultivars and/or making irrigation necessary practice.