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Gas exchange and water-use efficiency of cv. Sangiovese grafted to rootstocks of varying water-deficit tolerance
- Galbignani, M., Merli, M. C., Magnanini, E., Bernizzoni, F., Talaverano, I., Gatti, M., Tombesi, S., Palliotti, A., Poni, S.
- Irrigation science 2016 v.34 no.2 pp. 105-116
- Vitis, canopy, carbon dioxide, drought, drought tolerance, gas exchange, genotype, global warming, irrigation, leaf area, leaf water potential, problem solving, rootstocks, summer, transpiration, water stress, water supply, water use efficiency
- Testing of new rootstocks for drought tolerance targets traditionally rain-fed districts where supplemental irrigation is more frequently needed due to the pressures of global warming. A seasonal evaluation of gas exchange and water-use efficiency (WUE) of cv. Sangiovese grafted to the new drought-tolerant genotype M4 in a dry-down trial against the commercial SO4 stock is reported. The experiment was conducted in 2014 on twelve 2-year-old, non-fruiting potted Sangiovese grapevines grafted on M4 and SO4 stocks and assigned to SO4-WW (well-watered), SO4-WS (water-stressed), M4-WW and M4-WS treatments. Progressive water deficit was imposed by reducing water supply to 70, 50 and 30 % of whole-canopy demand derived from concurrent measurements of transpiration in WW. Unlike SO4, M4 showed slower stress progression, as highlighted by pre-dawn leaf water potential, and retained higher whole-canopy net CO₂ exchange rates (NCER) and transpiration rates per unit of leaf area at all replenishment levels as well as exhibiting higher canopy WUE at both 50 and 30 % WW. Although single-leaf assessment was in partial disagreement with data recorded on the whole-canopy basis, robust data were acquired to confirm that the M4 stock performs better than SO4 at any water replenishment level in terms of higher NCER/leaf area and/or canopy WUE. Findings feed expectations that grafting Sangiovese to the M4 rootstock should result in a problem-solving tool for rain-fed areas subject to temporary summer drought.