Crop yield response to water - Cra

Figure 4Effects of the level of applied water expressed as a fraction of reference ET (ET o ) on canopy volumeand on the yield canopy volume ratio.11014100yield/canopy9012Canopy volume (m 3 )807060504030canopy volume10864Yield/canopy volume (kg/m )320102020 40 60 80 100 120Percent ET o0conditions, irrigating every 2-3 days is more desirable. Experiments in Chile have shown thatallowing 50 to 60 percent soil water depletion between irrigation applications (every 5-6 days)did not affect yield and fruit size as compared to more frequent applications (Ferreyra, et al.,2006). Irrigation frequencies that deplete about 25-30 percent of the tree-water reservoir areadequate for most soils as a compromise to maintain both adequate water and oxygen supplyto the avocado root system. Under drip irrigation, it is important to be able to leach the excesssalts out of the potential root zone, and to wet enough soil volume particularly in shallow,coarse-textured soils. Fruit oil content is an important quality feature that is negatively affectedby inadequate irrigation.All experimental evidence so far indicates that RDI is not a recommendable practice for irrigationof avocadoes, because of the high sensitivity of commercial yields to water deficits duringmost of the irrigation season. On the other hand, excess irrigation is highly detrimental, giventhe sensitivity to water logging and the high risks of fungal disease infection. Best irrigationpractices for avocado should be based on supplying ET c at optimal intervals that both preventtree water deficits and supply adequate oxygen to the root system.446crop yield response to water