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Certain physiological parameters, namely leaf water potential, stomatal resistance and rate of photosynthesis of Chenin blanc grafted onto 10 rootstock cultivars on a relatively saline soil under irrigation in a hot region (V), were measured for two growing seasons. Soil electrical resistance, which varied from 632 to 271 ohms in the shallower soil layers (<500 mm) and from 414 to 167 ohms deeper in the soil, decreased during the growing seasons. Although diurnal and seasonal patterns of change of the physiological parameters measured did not differ between rootstock cultivars, significant differences in their magnitudes were apparent. The rootstocks US 16-13-23, 13-5 E.V.E. Jerex were more stressed than 101-14 Mgt, 143-B Mgt and 110 Richter and had lower rates of photosynthesis. Photosynthetic rate was predominantly inversely correlated with stomatal closure. The use of 101-14 Mgt and 143-B Mgt is recommended under relatively saline conditions.

The performance of Chenin blanc grafted onto 15 different rootstock cultivars and clones, established on a sandy alluvial soil in the Montagu district, was investigated. Over the eleven years of the trial, the highest mean yields were obtained with 99 Richter (Clone: RY 13), Constantia Metallica, Dog Ridge, Ramsey and 101-14 Mgt. The mean yield of99 Richter (Clone: RY 13) was significantly higher than that of the other 99 Richter clones and selections. The highest pruning masses were found with 143-B Mgt, Dog Ridge, Constantia Metallica and Ramsey. The crop-to-pruning-mass ratio of 143-B Mgt was, however, lower than that of the other graft combinations, which suggests that this graft combination was undercropped and that potentially higher yields could have been obtained. Moderate growth was obtained with the cultivars 101-14 Mgt and 3306 Coucerc. These cultivars showed potential as growth-limiting cultivars as they consistently produced relatively high yields with satisfactory grape composition, associated with low pruning masses.