Long-Term Effects of Deficit Irrigation and Subsequent Recovery of Young Japanese Plum Trees

Abstract

Different deficit irrigation strategies were carried out during seven consecutive years in a young Japanese plum drip irrigated orchard in Spain. The long-term effects of these treatments are summarized. By the end of the seventh year, the water restrictions did not lead to any soil salt accumulation in the dripper zone, a concern when deficit irrigation is applied in the long-term. However, the water restriction led to smaller trees (28% in canopy shaded area). This had a carry over effect on yield which was reduced by 18% in the eighth season, when trees were fully watered, compared to the control. After the seven years of deficit irrigation, several watering and crop load regimes were employed in order to accelerate the recovery of the vegetative growth. The more successful strategy was increasing the wetting zone by adding drippers with water application up to 133% of crop evapotranspiration. This was particularly effective when carried out together with lowering the crop load in order to alleviate the vegetative versus fruit growth competition. After two years of applying this strategy, the previously deficit irrigated trees were able to obtain a similar tree size than the control trees. The results provide for some insights on how to manage the watering regime when a scenario of full water availability follows a drought cycle.