Crop yield response to water - Cra

The most critical developmental period for avocado take place between late spring and earlysummer. At this time, there is vigorous shoot and root growth, the fruit are set and their finalsize is defined. Environmental stress could negatively affect fruit set, final fruit numbers andfruit size. It may induce some fruit internal defects as well. During that period, evaporativedemand is relatively low and variable, and thus it is possible this inadequate irrigation practicescause water deficit or excess. Even though fruit expansion rates are quite high during a shorttime period, as shown in Figure 3, fruit growth and development takes a long time, fromspring to fall. Fruit shape is also affected by temperature; it becomes more elongated withlower average temperatures.Responses to Water DeficitsAvocado trees are quite sensitive to water deficits; it has been determined that theirinflorescences are more sensitive to water deficits than the surrounding leaves. The sensitivityof fruit set to water deficits is also quite high, and fruit drop may occur at any time betweenfruit set and about 50 percent of final size, if water stress is induced by lack of irrigation. Fruitsize is affected by water deficits during its growth period that lasts about four months afterfruit set. Water stress during fruit development in the later stages of fruit growth negativelyaffects the quality of mature fruit. When trees are frequently irrigated calcium concentrationin the fruit increases and this seems to prevent several fruit physiological disorders.Figure 3Expansive growth of an avocado fruit of the cv. Hass, monitored continuously in central Chile.5045Growth (mm)40353025Nov. 2004 Dec. 2004 Jan. 2005 Feb. 2005 Mar. 2005 Apr. 2005 May 2005 June 2005Date444crop yield response to water