Issue link: http://winesandvines.uberflip.com/i/264184
p r a c t i c a l w i n e r y & v i n e ya r d M a r c H 2 0 1 4 51 g r a p e g r o w i n g T E C H N I C A L R E S O U R C E F O R G R O W E R S & W I N E R I E S 58 Soil moisture and mineral nutrient status by Michael Sipiora 64 Mating disruption of vine mealybug by David Langone, S. Kaan Kurtural and Kent M. Daane 68 Practical common sense for winery management by Stuart L. Scott practicalwinerylibrary.com Access Practical Winery & Vineyard article archives online. I rrigation budgeting and strategies to optimize both the utilization and acquisition of water resources are criti- cal to maximize vineyard profitability. Maximizing the returns (crop yield and fruit quality) and water-use efficiency (WUE) are not only compatible objectives, they are also necessary objectives, partic- ularly in environments with limited (and potentially diminishing) water resources. In such environments, irrigation is likely to move from being a yield/growth strat- egy to a risk-management strategy. Irrigation is a management tool that allows growers to directly manipulate vine growth, crop yield and fruit quality. Approximately 87% of the Australian wine grape production comes from regions that rely wholly or partly on irri- gation water. Water costs can be as high as AU$3,000 per megaliter (ML) and power costs to move water continually increase. In recent years, wine grape producers in southeast Australia have started the grow- ing season with anywhere between 0% and 70% water allocations. Similarly, in southern parts of southwest Western Aus- tralia, irrigation resources have been lim- ited and irrigation allocations have been based on risk minimization strategies. Optimizing utilization of water Production water-use efficiency Production water-use efficiency (WUEp) is how water utilization is generally mea- sured and compared. It is defined as the amount of crop produced per unit of water applied as irrigation and effective rainfall and is therefore an outcome of the efficiency by which water reaches vines and how the vines access and transpire water in fixing carbon. M.R. Gibberd et al. and S. Tyerman et al. proposed that there are several sources of variation associated with WUEp. 6,7,27 1) Irrigation efficiency: This relates to the proportion of applied water trans- pired by the vine. For this efficiency to be optimal, water loss through run- off, drainage, leakage, evaporation and cover crop transpiration must be mini- mal. Water-management practices must also be optimal since this efficiency is dependent on both the water delivery infrastructure and how water is applied to optimize production. 2) Transpiration efficiency: the amount of carbon fixed during photosynthesis per unit of water transpired by the vine. Much of the variation in this efficiency can be attributed to variation in vine genotype through differences in stomatal conductance and photosynthetic capacity. 3) Harvest index: The amount of total dry matter removed as harvested product. It is dependent on the supply of sugar from both photosynthesis and reserves and is important as it determines yield from the product of transpiration efficiency and the volume of water transpired. It is strongly influenced by scion and root- stock genotypes. Value water-use efficiency Water use can also be considered on a value basis. Value water-use efficiency (WUEv) is defined as the monetary value of the fruit or wine per unit of water applied as irrigation and effective rainfall. Whereas WUEp relates to the vineyard, WUEv relates to the vineyard-winery- marketplace continuum. This form of WUE also needs to be considered in the decision-making process since a reduc- tion in productivity as a consequence of deliberate or otherwise under-irrigation practices could be offset by a potential Tony Proffitt and Mark Gibberd, Curtin University, Department of Environment and Agriculture, Margaret River, WA, Australia BY Optimization of limited water resources in irrigated vineyards ACQUISITION AND UTILIZATION This article extends the research and technical information from the Grape and Wine Research and Development Corp. (GWRDC)-funded project titled Optimiz- ing Industry Returns From Existing Soil and Water Research. The aim of the proj- ect was to better inform industry about aspects of soil water management follow- ing the GWRDC-funded Soil and Water Initiative projects. Maximizing returns and water-use efficiency are compatible and necessary objectives in environments with limited water resources.