Crop yield response to water - Cra

is completed within 20 days; thereafter fruit grows rapidly and attains its maximum size bymid-May (Northern Hemisphere). At this time, about 90 percent of total fruit dry matter hasbeen gained (in early cultivars). In temperate regions, harvest starts by the end of May andlasts until the end of July; Northern Hemisphere).Leaf emergence takes place at the end of February followed by fast shoot growth rates. About80 percent of full leaf area is completed by the end of May. Thereafter, about 95 percent offinal leaf area is achieved by the end of June (Figure 3). Values of leaf area index (LAI) rangefrom about 2 in orchards with normal plantation density (∼400 plant/ha) up to 4.5 in orchardsplanted in high density systems (∼1 100 plant/ha) (Figure 3).In Mediterranean climates, vegetative shoot growth of apricot trees continues (especially inyoung orchards) for several months after fruit have been picked, until October. During thispostharvest period, carbohydrates and mineral elements stored in the different plant organs areof primary importance. Thus, it is important to provide sufficient mineral nutrition and watersupply from irrigation to protect the trees from abiotic stress, during the postharvest period. Inthis way leaf photosynthetic activity is maintained and extended until natural leaf senescence,and in turn, storage of reserves in shoots, buds, branches and main roots is maximized.Figure 3Seasonal LAI evolution in apricot orchards (cv. Tyrinthos) trained to Vase (400 plant/ha) andTransverse Y (1 111 plant/ha) (redrawn from Dichio et al., 1999).Transverse Y Vase5.04.54.03.53.0LAI2.52.01.51.00.50.00 50 100 150 200Days from leaf out434crop yield response to water