Journal of Experimental Agriculture International

Aims: This work was carried out to identify the optimal time of supplemental irrigation on a traditional rainfed olive orchard.

Study Design: Randomized complete block design with three replications where the variable factor was water regime.

Place and Duration of Study: Experimental station AinTaoujdate, Regional Agricultural Research Center, Meknès, Morocco during 2009 and 2010.

Methodology: Seven treatments of supplemental irrigation were tested, individually during one day at, beginning of stage I of fruit development (T_a); beginning of stage II (T_b); beginning of stage III (T_c) and in combination of two irrigations, T_a and T_b (T_ab), T_a and T_c (T_ac), and T_b and T_c (T_bc) in addition to three irrigations T_a, T_b and T_c (T_abc), and no irrigation used as control (T_d). Treatments were applied to thirty years old olive trees (cv. Picholine Marocaine) planted at a distance of 8x6 m, at experimental field of Regional Agricultural Research Center of Meknes in North-center of Morocco. Amount of each watering was equivalent to the easily usable water-reserve on 70 cm of soil depth (0.5 m³/tree).

Results and Discussion: Fruit weight and shoot length were more affected by treatment T_a as compared to the rainfed regime, and hence fruit and oil yields were increased, in average, respectively by 43% and 37%. Water use efficiency for this treatment was 23 kg.m^-3.tree^-1. Treatments T_b and T_c improved only oil content and shoot growth without significant changes in yield. However, their combination with T_a (T_abc) increased fruit yield by an average of 106%. The effect observed under the tested irrigations was related to the importance of fruit growth kinetics during water application.

Conclusion: The production gain of supplemental irrigation, applied particularly during the first period of fruit development, is promising to promote this technique on several rainfed olive orchards