Crop yield response to water - Cra

Lead AuthorDavid A. Goldhamer(formerly University of California,Davis, USA; currentlyCooperative Extension Emeritus)Contributing AuthorsDiego S. Intrigliolo(IVIA, Moncada, Valencia, Spain)Juan R. Castel(IVIA, Moncada, Valencia, Spain)Elias Fereres(University of Cordobaand IAS-CSIC, Cordoba, Spain)CitrusIntroduction and BackgroundCitrus fruit include oranges, which account for about 70 percent ofworldwide production, small citrus fruit, such as mandarins, tangerines,tangelos, clementines, satsumas, lemons, limes and grapefruit. Orangesare produced for both the fresh market and for juice — chilled single strengthand concentrate. Until the middle of the twentieth century, citrus was almostexclusively cultivated locally. Speed and care when shipping the perishablefruit was of great concern. However, the development of citrus concentratehad a lasting impact on the citrus industry worldwide. Concentrating the fruitpermitted the storage, transportation, and transformation of the productfar from the groves. In addition to fresh fruit and juice, there are citrus byproductssuch as food additives, pectin, marmalade, cattle feed (from thepeel), cosmetics, essential oils, chemicals and medicines.Because citrus is an evergreen crop sensitive to low temperatures, subtropicalregions produce the bulk of the world’s citrus. Tropical cultivation is not asproductive since seasonal changes in temperature favour adequate bloomingpatterns, fruit growth and fruit colour development during ripening. Infact, the high temperatures of the tropics induce fast development andproduction of large fruit that ripen quickly, remaining marketable for a veryshort time. In contrast, growth in the subtropical zones slows in the winterand fruit can remain mature on the tree for longer before it is harvestedand marketed. Frost damages citrus fruit although the trees can withstandshort periods of light frost. However, hard frosts of long duration kill treesand can be devastating.Citrus fruit value ranks first in international fruit trade. In 2009, there wereover 5.4 million ha of citrus (4.1 million ha of oranges) with an average yieldof 16.3 tonne/ha. Figure 1 presents the trends since 1985 of the productionof the world principal countries (FAO, 2011). As a result of trade liberalizationand technological advances in fruit transport and storage, the citrus fruitindustry is becoming more global. During the last decades, citrus productionand trade have increased steadily; although the intensity of growth variedaccording to the type of fruit (it has been stronger for small fruit and juice).Citrus production is evolving in a context of highly competitive globalmarkets. There is an apparent ever-increasing focus on the quality and thevalue-added aspects of the products. Citrus is often promoted for its healthand nutritive properties; rich in Vitamin C, folic acid, and fibre.316crop yield response to water