Productivity of water, growth and yield of olive trees under deficit irrigation

The objective of this study was to investigate the impact and potential of different deficit irrigation treatments on olive yield, water saving and vegetative growth for two local Jordanian olive cultivars, Olea europaea 'Nabali Baladi' and 'Nabali Muhasan'. The study was carried out in a 10-year-old olive orchard located at Mafraq in north Jordan. The study extended for four seasons (2012-2016), representing three on-year seasons and one off-year season. Six irrigation treatments were applied: 80% of the crop evapotranspiration (ETc) for the full season; 80% ETc until the last 2 months before harvest; 80% ETc followed by 50% until 1 month before harvest; 80% ETc for 2 months followed by 50% and then 80% until 1 month before harvest; 40% ETc for 4 months followed by 100% until 2 month before harvest; and 100% ETc as a control. The percentage of irrigation water applied was 80, 65, 51, 62, 53 and 100% for on-year seasons and 80, 68, 60, 60, 52 and 100% for off-year season, respectively, for the six treatments. Results showed that there were no significant differences in olive yield, trunk diameter or shoot growth among the treatments for the two cultivars. Furthermore, using 65% ETc proved to give the highest water-use efficiency among the other treatments for both studied cultivars. The study concluded that the application of deficit irrigation to olive trees under Jordanian conditions had no negative effect on tree vegetative growth or yield and enhanced water saving.