Crop yield response to water - Cra

same cultivar but used in Italy and Spain, respectively); (Naor et al., 2000; and Marsal et al.,2002a), and two other studies on the cv. Conference; the latter dealing with postharvestdeficit irrigation (Marsal et al., 2008; and Marsal et al., 2010). In these four studies it has beenconsidered that: i) annual ET o and effective rainfall were known, ii) ET c was estimated fromsoil-water content variation and applied water, and iii) the effects of irrigation on fruit yieldwere considered for two consecutive years. Figure 5 shows the relation between relative fruityield and relative ET c . Relative yield is unaffected by ET c deficits of 15-20 percent and thendeclines more or less linearly as ET c deficits become more severe.Figure 6 shows the water production function considering relative gross revenue instead ofyield as a productive parameter. The relative gross revenue penalizes fruit with cheek diametersof less than 65 mm. The prevailing market conditions are very different between these twocultivars, since Conference pears commonly receive a better price than Blanquilla. Prices maychange from country-to-country. For the sake of a fair cultivar comparison and to avoid thespecificity of country market effects on gross revenues, the pricing criterion of Conference inSpain was applied to all reported experiments.Figure 5Production function developed for RDI strategies that imposed stress during Stages I and II.Data points were obtained from studies of at least two-year duration. Three studies from Spainand one from Israel were used for the relationship (Source: Marsal et al., 2002a in Blanquilla;Marsal et al., 2008 in Conference; Marsal et al., unpublished in Conference; and Naor et al., 2000in Spadona). Linear boundary lines consider separate cultivar fitting through linear regressionfrom the observations defining an upper boundary. FI, RDI-SI, RDI-SII, RDI-PH and SSDI standfor full irrigation, RDI during Stage I of fruit growth, RDI during SII of fruit growth, RDI duringpostharvest and seasonal sustained deficit irrigation, respectively.1.00.8Blanquilla - Spain OverirrgationBlanquilla - Spain FIBlanquilla - Spain RDI-SIBlanquilla - Spain RDI-SIIConference - Spain FIConference - Spain RDI-SIIConference - Spain RDI-PHSpadona - Israel SSDIRelative yield0.60.4Slope Blanquilla = 1.2Slope Conference = 1.00.20.00.00.20.40.6 0.81.0Relative ET C384crop yield response to water