Deficit irrigation is a strategy that in the short term often allows increasing water use efficiency with minimal
impacts on tree performance. However, the long-term and carry-over effects of this practice have not
been sufficiently investigated. Here, we report a research that was conducted over eight years in a young
Japanese plum orchard planted with cv. Black-Gold in Valencia, Spain. Different deficit irrigation and crop
load regimes were applied in the first seven seasons. In the last experimental season, however, all trees
were well irrigated in order to explore the possible carry-over effects of the water restrictions applied
previously. The results obtained indicate that under the experimental conditions of the current research
(low irrigation water salinity, and Mediterranean climate with some intense rainfall events during fall
and spring), deficit irrigation applied for seven consecutive seasons did not lead to accumulation of salts
in the soil, a concern when deficit irrigation is applied in the long-term. Nonetheless, water restrictions
impaired the fruit bearing capacity quantified as the number of fruit per unit branch length before thinning
application. This effect was partly explained by a decrease in the concentration of starch reserves in
the root system in one of the deficit irrigated treatments. A decrease in the fruit bearing capacity itself did
not impair yield as the cultivar employed in this study required intense thinning that offset the initial differences
in the number of fruit per branch length. However, deficit irrigation led to smaller trees (31% in
tree shaded area in the most stressed treatment against 47% in control trees). This effect was the ultimate
cause of the 29% yield reduction observed in the eighth season, when the previous deficit irrigated trees
were fully watered. It is then concluded that deficit irrigation strategies in developing orchards should
be used with caution. Only slight restrictions can be imposed in order to avoid the long-term carry-over
effects of deficit irrigation on tree performance.