ISHS Acta Horticulturae 171: I International Symposium on Water Relations in Fruit Crops
EFFECT OF SOIL WATER CONTENT ON LEAF WATER POTENTIAL AND STOMATAL RESISTANCE OF GRAPEVINE (VITIS VINIFERA) GRAFTED ON DIFFERENT ROOTSTOCKS. |
| Authors: | S. Natali, C. Xiloyannis, M. Castagneto |
| Abstract:
Water deficit stress tests were carried out on Sangiovese vines on own roots, grafted on Kober 5BB and on 140 Ruggeri, and on the rootstocks themselves. The vines were three years old and grown in containers. Leaf water potential values taken before sunrise were a useful parameter in estimating available water content in the soil; these parameters were strictly correlated. In general the leaf water potential in irrigated plants never reached values lower than -1.2 MPa during the hours of high transpiration demand. Conductance in the irrigated plants varied between 1–1.5 cm sec-1, while a reduction of Stressed plants (-1.5 MPa before sunrise) showed no substantial reductions of leaf water potential during the day. This behaviour was confirmed by a minimum transpiration activity revealed by diffuse resistance measurements. Recovery in stressed plants was rapid, and leaf water potential values surpassed those of the control plants during the hot hours of the day. In the late afternoon leaf rehydration rates in control plants were higher. The immediate recovery of the stressed leaves was not confirmed by the leaf water potential values taken at dawn the following day. The rapid recovery observed in leaf water potential immediately after irrigation was therefore temporary; the leaf restabilizes completely only one or two days after irrigation, when stomatal conductance is also normalized. High stomatal resistances were in fact observed during the recovery phase, confirming the existance of an inertia prior to the complete recovery of stomatal functioning. | |
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l to -0.6 MPa (measure before sunrise) was enough to lower the conductance to 0.1–0.05 cm sec-1.
