Photosynthesis, leaf and stem water potentials, chlorophyll and macroelement leaf concentration as influenced by two root and training systems in Erbaluce wine grape.

Leaf gas exchanges, vine water status, chlorophyll and macronutrient leaf concentration were evaluated in ‘Erbaluce’ grapevines. Vines were grown ownrooted and grafted on ‘Kober 5BB’, and were trained to calusiese pergola (CP) and alternate curtain (AC) in the typical growing area of this Italian cultivar (Piedmont, North Italy). In order to point out differences in physiological behavior under maximum diurnal air temperature and air evaporative demand, measurements were taken at 12:00 and at 15:00 local solar time. Training system exerted a noticeable influence on the tested parameters while only few differences were related to the root system. Greater values of leaf temperature and vapor pressure deficit were measured in July and August on AC, which foliage is more sun- and air-exposed due to the canopy structure; under this ambient conditions, leaf gas exchanges were depressed. On the opposite, CP had higher leaf N concentration, higher rates of leaf gas exchanges and of net CO2 assimilation per N content. Possible causes of variations in leaf concentration of the other macroelements are also discussed. Changes of water status in vines trained to AC seemed related with changes in the shoot position during their free growth and elongation. Ownrooted vines showed a higher leaf Magnesium concentration and, in June and early-July, a lower water status.