Crop yield response to water - Cra

Water RequirementsThe water use rates of peach trees are similar to other Prunus species, such as nectarines orplums. Table 1 lists the crop coefficients for mature peach trees, and an estimation of the wateruse at Lleida, Spain. The crop coefficients were obtained from lysimeter studies (Ayars et al.,2003). In one study, the ET c of a peach tree in a weighing lysimeter was followed for severalyears since its planting until it reached maturity. This study has provided data on the evolutionof K c for a peach orchard, as the canopy expands (Ayars et al., 2003), and the results are shown inFigure 5. The lysimeter studies have shown that Tr in peach does not decrease much from peakvalues until soon before leaf fall, unless the water deficits imposed by restricting irrigation in thepostharvest period induced stomatal control of Tr and early leaf senescence.Water Production FunctionsA number of experiments have been conducted to quantify the relation between yield andapplied irrigation water for peach (Girona et al., 2002). A summary of some of the experimentsTable 1Crop coefficients relative to grass reference crop (ET o ) for mature peach trees (Phenologicalstages for midseason cultivar at Lleida, Spain).Date Crop Coefficient (K c ) Growth StageMar. 1-15 0.25Mar.16-31 0.30 BloomApr. 1-15 0.45Apr. 16-30 0.60May 1-15 0.70May 16-31 0.80 End of FGS I *June 1-15 0.90June 16-30 0.95 Beginning of FGS III *July 1-15 1.05July 16-31 1.05Aug. 1-15 1.05 HarvestAug. 16-31 1.00**Sept. 1-15 1.00**Sept. 16-30 1.00**Oct. 1-15 0.75Oct. 16-31 0.55Nov. 1-15 0.45* FGS = Fruit growth stage** Management reductions in postharvest irrigation may lower these K c values402crop yield response to water