Differences in the effects of flooding the soil early and late in the photoperiod on the water relations of pot-grown tomato plants

Abstract

The water relations of potted tomato plants (Lycopersicon esculentum Mill. cv INCA 9(1)) submitted to two flooding/recovery cycles imposed at the beginning and at the end of photoperiod were studied under controlled conditions. In both experiments, flooding induced stomatal closure due to leaf dehydration linked to a lowered root hydraulic permeability. Thus, during the early hours of flooding there was an effective negative hydraulic message from O2 deficient roots. However, when the soil was drained stomata did not re-open until some time after leaf water potential and leaf turgor potential returned to normal, supporting the view that chemical messages predominate. Flooding imposed at the end of photoperiod induced a delay in gl, Ψl, and Ψp, recovery.