Maurizio Zamboni

Morpho-structural and physiological response of container-grown Sangiovese and Montepulciano cvv. (Vitis vinifera) to re-watering after a pre-veraison limiting water deficit

A better physiological and productive performance of cv. Montepulciano versus cv. Sangiovese under well-watered conditions has been recently assessed. The objective of this study was to verify that this behaviour is maintained when a pre-veraison deficit irrigation (vines held at 40% pot capacity from fruit-set to veraison) followed by re-watering (pot capacity reported at 90%). Single leaf assimilation rate and stomatal conductance, diurnal and seasonal whole-canopy net CO2 exchange (NCER) and water use efficiency were always higher in Sangiovese under deficit irrigation. Due to water shortage Montepulciano displayed a more compact growing habit due to decreased shoot and internode length. Sangiovese showed excellent recovery upon re-watering as NCER resulted to be higher than the pre-stress period; however, this might also relate to early and severe basal leaf yellowing and shedding. Early deficit irrigation affected xylem characteristics of Montepulciano more than in Sangiovese; vessel density increased (37 vs 29%, respectively, compared with well-watered vines) and the hydraulic conductance decreased more (-13 vs -3% respectively) compared with well-watered vines. Yield components and technological maturity were similar in the two cultivars, whereas Montepulciano grapes had lower anthocyanins and phenolics. Higher physiological and productive efficiency under non-limiting water conditions showed by Montepulciano compared with Sangiovese was basically reversed when both cultivars were subjected to an early deficit irrigation.

Effects of Early Shoot Trimming of Varying Severity on Single High-Wire Trellised Pinot noir Grapevines

Amid growing concerns over global warming and available management strategies to reduce cluster temperature and prevent overheating and sunburn damage, there is increasing interest in sprawling, nonpositioned canopies as an alternative to traditional vertically positioned ones. However, management of sprawling canopies requires adjustments to maintain a mostly erect growth pattern during the season. A three-year study (2009–2011) was carried out to investigate the performance of 15-year-old Pinot noir grapevines trained to a single high-wire trellis subjected to prebloom shoot trimming to retain seven (T7) or eleven (T11) main stem leaves. There were significant year × treatment interactions: with a low crop and weather conducive to posttrimming lateral regrowth in 2010, trimmed vines had higher leaf area, soluble solids concentration, pH, total anthocyanins, and cluster rot incidence than control vines, whereas in 2009 and 2011, the overall must compositional pattern was reversed due to suboptimal leaf-to-fruit ratios in the trimmed plots. The effects linked to this necessary operation are highly dependent on unpredictable weather occurring after shoot trimming; hence, the milder trimming severity (T11) may more successfully balance the need to induce a still mostly erect canopy while retaining sufficient vine leaves to buffer possible weak lateral formation after trimming. This paper provides new and useful knowledge for improved canopy management in trellises with free shoot growth due to the absence of foliage wires.