Flower development and fruit malformation in strawberries after short-term exposure to high or low temperature

Strawberry plants are at risk of exposure to short-term high daytime temperature (HTD) during flowering and exposure to short-term low temperature at night (LTN) during the coldest months of winter. The aim of this study was to identify the effects of short-term HTD or LTN on the different floral developments and fruit development, such as fruit malformation, flowering traits, stigma maturation, and pollen quality in 'Seolhyang' and 'Maehyang' strawberries. For the treatment of HTD, plants were treated at 35 degrees C, and for LTN treatment, plants were treated at 2 degrees C for consecutive days each. Days to flowering were shortened under HTD in both cultivars, while days to anther dehiscence were shortened under HTD. Stigma maturation was delayed by short-term extreme temperature stress in 'Maehyang'. Short-term LTN before the flower petals appeared in the first and second flower clusters might cause high malformation rates in both cultivars. Pollen viability and the germination rate were decreased by HTD and LTN in both cultivars. There was a high correlation between the lower pollen germination rate and the higher percentage of malformed fruits under short-term LTN. These results suggest that even shortterm exposure to low temperature in winter during cultivation should be controlled carefully considering developmental stages and cultivar-specific responses and that attention should be paid to the protection of strawberries.N