Effect of irrigation and fertilization on fruit and wine quality

The subject of irrigation of wine grapes has undergone quite a considerable evolution during the last decades and is currently not associated only with new world wine production. Irrigation is now permitted (with some restrictions) in many European countries known for their traditional so called "old world" wine producers. The OIV (International Organization of Vine and Wine) has recently adopted a resolution that supports irrigation of winegrapes provided it is being used for regulating vigor and production (resolution viti 2/2003). Drip is presently the leading irrigation technology for grapes, it opens new avenues for improving production and quality of the fruit and the wine. Frequent irrigations of low soil volume enables rapid control of the water availability without interfering with soil aeration and thereby control of the vegetative growth at each stage of growth throughout the growing season. Irrigation depth can easily be controlled, thereby minimize fertilizers and other chemicals leaching to layers below the root zone. The use of fertigation enables to control the concentration and the composition of various mineral elements in the major root zone since plant roots take up minerals according to concentration gradients rather than to amounts per Ha. Controlling the concentrations and the composition of the minerals in the soil solution also provide means for controlling the uptake rate of various mineral elements. Concomitant leaf mineral analyses at several stages of growth and development can help to optimize the nutritional status of the vines. Since various flavor and aroma compounds are formed at different stages of growth and development, it is possible to affect the biosynthesis and accumulation of each of them by regulating the vegetative growth at each stage and thereby reducing sink competition between vegetative growing tips and developing fruits. Regulation is particularly needed in cases of high vigor vines and can be achieved by either topping or imposing water stress.