Crop yield response to water - Cra

Figure 4 Relationship between relative fruit yield and relative ET c for olive. Curve was obtained forthe cv. Picual in Cordoba, Spain (Moriana et al., 2003), and data points obtained fromadditional studies (Lavee et al., 2007; Iniesta et al., 2009; Martin-Vertedor et al., 2011;Gucci et al., 2007 and Caruso et al., 2011) for different cultivars, as shown in the graph.100Fruit Yield (%)80604020040 50 60 70 80 90 100ETc (%)to mild ET c deficits than the cv. Picual. More research is needed to characterize the responseof the other cultivars in different environments. From the original data sets and equationsin Figure 4 for Cordoba, Spain, over 700 mm of water consumed in ET c are needed to reachthe maximum olive fruit yield in that particular environment. If the effective rainfall is 400mm, at least 300 mm would have to be supplied by irrigation to achieve maximum yields inthat particular location. However, because of the shape of the yield response to ET c , oliveproduction responds very well when small irrigation amounts are applied to rainfed orchards.In different locations in southern and northeastern Spain (between 350-500 mm of annualrainfall), farmers are achieving WP values of up to 30 kg/ha/mm (fresh fruit) with seasonalirrigation applications of 100 to 150 mm in orchards that were previously rainfed. In coastal,central Italy (about 600 mm annual precipitation), less than 100 mm of irrigation water aresufficient to obtain yields that are over 80 percent of those of fully irrigated orchards (Gucciet al., 2007). Significant increases in yield were obtained in Israel using a single irrigation of75 mm in the middle of the summer (Lavee et al., 2007).The yield response curve to applied irrigation water is similar to Figure 4 but flatter at highirrigation levels, because the olive is capable of extracting substantial stored soil water andcan compensate for reductions in applied water, as long as there is sufficient water in the rootzone. The level of irrigation savings depends on the storage capacity of the soil and on theamount of rainfall needed for the sustainable replenishment of stored soil water. The responseof oil production is similar to that of the response of fruit production, and the responses of oilquality are discussed below.The yield response of table olives to a reduction in applied water (AW) is shown in Table 2 fromone study (Goldhamer et al., 1994). A reduction in AW of 21 percent did not affect fruit yield orrevenue. A further reduction down to 62 percent of maximum AW, decreased relative fruit yieldby 10 percent, and relative revenue by 25 percent. The more drastic reduction in revenue wasassociated with a lower price due to the reduction in fruit size.308crop yield response to water