Short-Time of Rehydration is not Effective to Re-Establish Chlorophyll Fluorescence and Gas Exchange in Two Cowpea Cultivars Submitted to Water Deficit

Low water supply frequently interferes on chlorophyll fluorescence and gas exchange. This study aimed to answer if a short-time of rehydration is efficient to re-establish chlorophyll fluorescence and gas exchange in cowpea plants. The experiment used four treatments (sensitive / water deficit, sensitive / control, tolerant / water deficit and tolerant / control). The sensitive and tolerant cultivars after water restriction had significant changes in gas exchange. On the third day, the stress caused lower for PN and gs in sensitive cultivar of 67% and 45%, respectively. After rehydration these parameters were not recovered significantly to two cultivars. In relation to chlorophyll fluorescence, water stress caused significant changes in all parameters evaluated of cultivars, being observed effects more intense on sensitive cultivar in the parameters F-v/F-m (38%) and F-o (69%). Rehydration did not promote recovery of the values of F-v/F-m and Fo to sensitive cultivar. Therefore, our study revealed that a short-time of rehydration is not effective to re-establish chlorophyll fluorescence and gas exchange in cowpea plants submitted to water deficit.