Water productivity in fruit trees orchards under water scarcity

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With growing water shortages, agriculture faces the challenge of increasing water productivity (WP). In this work, WP of two main crops, peach and olive, is evaluated for different cultivars and deficit irrigation practices. WP in peach was estimated over 4-7 years for three cultivars (early, mid-season and late-maturing), two rootstocks and two deficit irrigation strategies. In terms of yield/total water supply, the late maturing cultivar subjected to mild deficit irrigation, gave the highest WP (4.1 kg m-3), compared to the mid-season (3.0 kg m-3) and early cultivar (1.9 kg m-3). Full irrigation reduced slightly the performance of the most productive cultivar (3.7 kg m-3). Performances of early and mid-season cultivars were affected by rootstock. Interaction between mild deficit irrigation and vigorous rootstock induced better WP. Experimental work in olives targeted WP under contrasted environments. In northern Tunisia (450 mm annual rainfall), average yield for three cultivars ('Picholine', 'Chetoui' and 'Mansanille') planted at 6×6 m spacing on a clay soil, varied between 3.9-4.7 and 4.7-6.1 t ha-1, respectively when irrigation was increased from 100 to 200 mm. Under these restrictive conditions, the highest WP values were obtained for 'Picholine', respectively 0.77 and 0.86 kg m-3. However, in southern Tunisia (200 mm rainfall), the 'Chemlali' cultivar, conducted under intensive planting (4×4 m) on sandy soils, showed a drastic increase in production. With irrigation water supply of 200-400 mm, average yield reached 10-12 t ha-1, and WP 2.1 kg m-3. Adaptation to water scarcity is discussed on the basis of the obtained results.