Recovery of root hydraulic conductance and xylem vessel diameter following prolonged water deficit of maize.

To sustain crop growth following soil water deficit, it is essential to have rapid recovery of leaf gas exchange. One basis for rapid recovery would be the rapid return of root hydraulic conductance to predrought levels to support water transport to the plant shoot. In this study, transpiration and root hydraulic conductance were measured over a 9‐day recovery period following an initial water‐deficit treatment of three maize (Zea mays L.) cultivars. In addition, xylem vessel diameter was measured during the recovery period at different positions from the root tip. The initiation of recovery in the transpiration rate occurred in all three cultivars within 3 days after watering, although the root conductance and transpiration rate of one cultivar were much lower than the other two cultivars. Root conductance and vessel diameter increased more slowly than the recovery of transpiration. There was an indication that transpiration could have been limited by root hydraulic conductance only when its values were low during recovery. The relationship between hydraulic conductance and vessel diameter did not, however, indicate a Poiseuille's law relationship between the two variables. Overall, cultivar variability in recovery from water deficit of the transpiration rate and root hydraulic conductance indicates that the selection for rapid recovery of leaf gas exchange following water deficit could be an important component of genotype selection in maize breeding programs. Core Ideas: Root hydraulic flow characteristics are rarely studied following water‐deficit treatments.Transpiration in three maize cultivars recovered 3 days after watering.Root hydraulic conductance and xylem vessel diameter recovered over a longer time period than transpiration.Differences were found among cultivars in their temporal recovery pattern of hydraulic flow characteristics. [ABSTRACT FROM AUTHOR]