Floral biology of ‘Bulida’ apricot trees subjected to postharvest drought stress

SUMMARY Drip irrigated ‘Búlida’ apricot trees (Prunus armeniaca L., on Real Fino apricot rootstock) were submitted to drought stress by withholding irrigation for two different postharvest periods for two consecutive years. The first treatment (T–1) started immediately after harvest, and lasted 11/2 months, while the second treatment (T–2) started when the first treatment finished and lasted 2 months. These stress treatments were compared with a control treatment (T–0), which was irrigated throughout the year so that it received an amount of water equivalent to 100% of the crop evapotranspiration (ETc) demand. Flowers from the three treatments showed similar quality (fresh weight, petal surface area and pistil length) and frequent macrostyle (stigma located above the anthers). A lower percentage of pollen germination was observed in grains from the following year's bloom in plants from the T–1 treatment. The T–1 drought stress also induced a significant decrease in fruit yield, due to an increase in fruitlet drop, which led to significantly lower fruit set. The T–2 treatment did not affect these processes and was not critical as regards apricot yield. The fruits harvested met the required standards of quality in all treatments.