Whether hydraulic conductance recovers after rehydration following a drought stress by repairing embolism while plant is transpiring or not is controversial. We rehydrated potted grapevines at 07.00 h after a stress period of ten days when pots had not been watered. During subsequent 24 hours we measured leaf transpiration rate, leaf water potential, and hydraulic conductance of leaves, petioles, and shoot and root segments. Degree of embolism was determined by comparing the initial hydraulic conductance of plant organs to the maximum hydraulic conductance after removal of air emboli after transient flushings of degassed water by HPFM technique. Increasing pressure during transient flushings ranged from 30 to 500 kPa in leaves, from 20 to 400 kPa in petioles and in shoot segments, and from 8 to 250 kPa in root segments. Leaf transpiration rate increased from 0.10 to 2.50 mmol*m-2*s-1 from 07.00 to 11.00 h, 4 hours after rehydration; thereafter it slightly decreased till 21.30 h, and it was null during the night. Leaf water potential was -1.10 MPa at 07.00 h; it was -0.40 after the first 3 hours, and -0.15 either at the and of the day or the subsequent morning. Recover in hydraulic conductance caused by rehydration (i.e. embolism repair) was about 80% in the leaf during the day (from 07.00 to 21.00 h) and a 10% more during the following night. We measured a 80% embolism repair after 11 hours in petiole, and after 8 hours in shoot. In root segments, embolism repair was about 60% during the day (from 07.00 to 21.00 h) and a 20% more during the following night. We conclude that leaf water potential quickly recovers after rehydration, while by contrast, embolism repair is a slower phenomenon, also occurring during leaf transpiration.
Dynamics of embolism repair in grapevine rehydrated after drought stress
LOVISOLO, Claudio;PERRONE, Irene;PAGLIARANI, CHIARA;SCHUBERT, Andrea
2006-01-01
Abstract
Whether hydraulic conductance recovers after rehydration following a drought stress by repairing embolism while plant is transpiring or not is controversial. We rehydrated potted grapevines at 07.00 h after a stress period of ten days when pots had not been watered. During subsequent 24 hours we measured leaf transpiration rate, leaf water potential, and hydraulic conductance of leaves, petioles, and shoot and root segments. Degree of embolism was determined by comparing the initial hydraulic conductance of plant organs to the maximum hydraulic conductance after removal of air emboli after transient flushings of degassed water by HPFM technique. Increasing pressure during transient flushings ranged from 30 to 500 kPa in leaves, from 20 to 400 kPa in petioles and in shoot segments, and from 8 to 250 kPa in root segments. Leaf transpiration rate increased from 0.10 to 2.50 mmol*m-2*s-1 from 07.00 to 11.00 h, 4 hours after rehydration; thereafter it slightly decreased till 21.30 h, and it was null during the night. Leaf water potential was -1.10 MPa at 07.00 h; it was -0.40 after the first 3 hours, and -0.15 either at the and of the day or the subsequent morning. Recover in hydraulic conductance caused by rehydration (i.e. embolism repair) was about 80% in the leaf during the day (from 07.00 to 21.00 h) and a 10% more during the following night. We measured a 80% embolism repair after 11 hours in petiole, and after 8 hours in shoot. In root segments, embolism repair was about 60% during the day (from 07.00 to 21.00 h) and a 20% more during the following night. We conclude that leaf water potential quickly recovers after rehydration, while by contrast, embolism repair is a slower phenomenon, also occurring during leaf transpiration.
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