Impacts of irrigation volume on bloom and fruit set of sweet cherry (Prunus avium L.)

Management practices during the growing season must consider not only the needs of the current growing fruit, but also the needs of the developing buds; the initiation of floral buds in sweet cherry occurs during the previous summer. Deficit irrigation is a management tool used during the middle stage (Stage 2) of fruit development in many stone fruit crops, in order to effectively manage water resources. In sweet cherry, this middle stage is short and does not allow this management strategy to be sufficiently employed. Irrigation levels over the entire growing season are therefore set to ensure adequate current season’s growth, as water uptake by the fruit is directly related to both fruit size and potential value. This study investigated the impact of irrigation volume on yield one season (S1) and on the return bloom and fruit set in the following season (S2). Irrigation volumes were set as 50% less than (low), and 50% more than (high) the orchard standard (medium). The standard was determined and regulated by soil water potential. Yields were not significantly different however the number of fruit in higher size classes increased with increased irrigation levels. Early in S2 there was no significant difference between irrigation levels in either the level of return bloom, or fruit set. These results indicated that fruit set, fruit number and yield was not negatively affected by reduced volumes of irrigation in the previous season, but confirms that water uptake is important in fruit development during current season maturation and ripening. This study suggests that in sweet cherry, reductions in water use could be achieved during early fruit development. Indeed, deficit irrigation may be possible in sweet cherry during Stage 1 and Stage 2, thus increasing the period of time over which water savings could be made.