Crop yield response to water - Cra

The crop, where price can vary more depending on its quality, is wine grapes. In this case, itis known that prices may vary almost an order of magnitude even for the same variety andregion, depending on the quality of the grapes. This is (partly) reflected in the price of thewine, which is known to vary widely depending on its quality, as assessed by the markets. Ithas been shown that, generally, water stress improves the quality of wine grapes, dependingon its severity and on how the stress is managed.To quantitatively illustrate the influence of quality as affected by irrigation, Box 19 shows thegeneral yield production function of Box 18 with a revenue (relative gross income) productionfunction for two cases, which differ in the response to irrigation of fruit quality. In the firstcase (Box 19 a), water deficits have beneficial effects on fruit quality up to a point, after whichquality is reduced and so is the price of the product (red line).Strategies for reducing irrigation water use in fruit trees and vinesA major purpose of this publication is to offer practitioners a number of options for dealingwith water scarcity; where the supply of irrigation water is insufficient to meet the full cropdemand. In some cases, the strategies devised to apply less irrigation than that needed tobox 19 Relative revenue responses to variations in ET c when fruit quality affects product prices.In the first case (a), the revenue (blue line) increases with water deficits because prices(red line) are directly related to quality, which increases with water deficits until a point,and then decreases as water deficits become more severe. The price curve together withthe yield response line yield a revenue production function that has an optimum ET c andAIW below that needed to obtain maximum yields.a1000Applied irrigation4Relativerevenue%3Relative yield %503002Relativeprice %100Relative ET c10000Yield Response to Water of Fruit Trees and Vines 287