EFFICIENCE DE L’UTILISATION DE L’EAU : UN OUTIL D’AIDE POUR LE CHOIX VARIETAL EN OLIVERAIE INTENSIVE ?

Abstract

This work was carried out in northern Tunisia on a varietal olive (Olea europaea L.) collection, with the aim to evaluate the ability of these varieties to valorize water and to classify them following their water use efficiencies for shoot and fruit growth (WUEshoot and WUEfr, mm of fruit increase/m3 I+P) and for olive production (kg/m3 I+P). Growth parameters as well as the productions per tree were determined during 3 campaigns on 29 olives varieties accounting for 3 trees per cultivar. Results showed important differences between water use efficiencies. Those relative to fruits WUEfr ranged between 0.20 and 6.22 mm/m3 following the cultivar, with averages of 1.0 mm/m3 in 2010, 4.2 mm/m3 in 2012 and 3.3 mm/m3 in 2013. Values of up to 2 mm/m3 were obtained for cultivars Barouni and Madurel and of less than 1 mm/m3 were observed for „Koroneiki‟, „Arbequina‟, „Chemlali‟ and „Coratina‟. Average WUEp for olive production were equal to 1.49 kg/m3 in 2010, 2.02 kg/m3 in 2012 and 3.28 kg/m3 in 2013, with maximums observed for „Chemlali‟ (2.11 kg/m3 in 2010 and 10.06 kg/m3 in 2012) and „Galega‟ (7.74 kg/m3) and the minimums recorded for „Arbequina‟ in 2010 (0.72 kg/m3), „Manzanille‟ in 2012 (0.03 kg/m3) and „Sayali‟ in 2013 (0.59 kg/m3). To conclude, we can say that varieties valorize water differently. Values of WUE for fruit growth and olive production can be used indicatively to guide orchardists to choice the suitable cultivars when planting the olive trees, depending on their objective. Values of WUEfr are usefull for table olive orchards, while WUEp are more suitable for oil olive plantations. Values of WUEshoot are suitable for producing cuttings for nurseries. Particular attention should be given to soil coverage, which is determinent in ETc computation and which was found to be correlated to WUE