Conclusions
The data obtained in this study indicate that apricot-water relations were adversely affected by soil flooding, and that the differences between control and flooded plants were evident from the first day of the flooding. Plants grafted onto Real Fino apricot and Pollizo prune rootstocks developed similar mechanisms to confront short term soil flooding conditions (3 days), based on an early stomatal regulation, which prevented leaf tissue dehydration. Under long term soil flooding (6 days), severe leaf tissue dehydration were was noted (as a result of root system deterioration), which, in the case of plants grafted on Real Fino rootstock, caused wilting and the death of all plants.
The early leaf conductance and net photosynthesis response seems to suggest that porometric and/or photosynthetic changes are reliable bio-indicators of the altered behaviour caused by flooding in apricot plants, as has been proposed in lemon (Ruiz-Sánchez et al. 1996) and kiwi fruit (Savé and Serrano 1986). Flooding effects were more pronounced in apricot plants grafted onto Real Fino rootstock than in the plants grafted onto Pollizo prune. Also, flooding reduced the total biomass of Búlida/RF plants. Neither wilting nor desiccation was observed in Búlida/P plants. This indicates that the selection of rootstock is critical in reducing the impact of flooding in apricot plantations.