Gas Exchange and Flooding Stress of Highbush and Rabbiteye Blueberries

Abstract

Abstract Highbush ( Vaccinium corymbosum L. ‘Bluecrop’) and rabbiteye ( V. ashei Reade ‘Woodard’) blueberry plants were flooded in the greenhouse to determine how transpiration, stomatal conductance to water and CO 2 , residual conductance, and C assimilation are affected during flooding and recovery. Carbon assimilation was measured using a portable CO 2 analyzer and stomatal conductance using a steady-state porometer. Stomatal conductance and transpiration decreased significantly after 4 to 5 days of flooding, and responses were similar for highbush and rabbiteye blueberries. Carbon assimilation decreased for both species within 9 days and became negative in 11 to 19 days due to decreased photosynthesis, stomatal conductance to CO 2 , and high leaf temperatures, which increased respiration. Recovery after 24 days of flooding to preflood stomatal conductance values required 18 days for ‘Woodard’ and more than 18 days for ‘Bluecrop’. In laboratory experiments flooded plants were less responsive to changes in ambient CO 2 and vapor pressure deficits than unflooded plants, and flooding durations of greater than 9 days significantly decreased residual conductance of the leaves.