Modulation of chlorophyll contents and anti-oxidant systems in two cucumber varieties under waterlogging stress and subsequent drainage

SummaryCucumber (Cucumis sativus L.) is easily affected by heavy rain and subsequent periods of flooding during the Summer. In the present study, the physiological basis for the tolerance of cucumber plants to waterlogging and their ability to recover from this stress was investigated using two contrasting genotypes: the waterlogging-tolerant line, PW0832, and the waterlogging-sensitive line, PW0801. Chlorophyll contents, anti-oxidant enzyme activities, and levels of the products of lipid peroxidation were measured over 7 d under waterlogged conditions and for 7 d after recovery. The difference in tolerance level between the two genotypes was dependent on the early activation of their anti-oxidant systems and their respective rates of recovery from waterlogging stress. The elevated activities of superoxide dismutase (SOD) and catalase (CAT) played important roles in maintaining growth and facilitating the recovery of PW0832 from waterlogging stress. The low recovery capacity of PW0801 was associated with the damage caused by lipid peroxidation, a reduction in chlorophyll content, and decreases in SOD and CAT activities. The lower peroxidase (POD) activities in both cucumber genotypes under waterlogging stress compared with those in non-stressed control plants indicated that acclimatisation to waterlogging stress may not be dependent on POD activity.