Short-Term Flooding Effects on Gas Exchange and Plant Productivity of Cranberries.

Water is one of the most important resources in cranberry production. However, too much water in the root zone generally has an impact on gas exchange and plant productivity. Designing an adequate drainage system to evacuate this excess of water requires the determination of a maximum flooding time. The objective of this study was thus to investigate the effects of flooding on gas exchange and plant productivity of cranberries subjected to short-term flooding conditions in four development stages. A complete randomize block design was set up in a growth chamber using 6-years old cranberry plants collected from the field (as 0.06 m²mat of vines) and grown in 27 litre containers filled with sand. Treatments consisted of flooding time varying from 24 to 120 hours and were applied during bud elongation, flowering, fruit development and fruit maturation. Measurements of gas exchange were performed each day during treatments and plant productivity was measured at the end of the experiment. In the bud elongation stage, photosynthesis rate (Pn) and stomatal conductance (gs) of the flooded cranberry plants were reduced by 29 and 37%, respectively, after the first 24 hours of flooding compared to plants in the control treatment, which were never flooded. After 120 hours of flooding, Pn and gs had declined by 47 and 68% compared to controls. Similar results were found in the other development stages. Evapotranspiration, measured one week following the end of flooding, was lower in treatments flooded more than 48 hours in the bud elongation stage but no difference was found among treatments during the other stages. Overall, the number of berries per container was lower in the treatments flooded more than 24 hours. The maximum flooding time parameter used in drainage system conception should be 24 hours for maximizing gas exchange and plant productivity in cranberry production. Optimizing drainage with this criterion should promote productivity in field conditions.