Ecophysiological and metabolic effects of different canopy management on Erbaluce vines trained to the pergola system

Abstract

During the 2023 productive season, we carried out an experimental test on the white berry variety Erbaluce, an autochthonous cultivar from Piedmont, to evaluate the ecophysiological and metabolic effects caused by different green pruning approaches. The vines were divided into two groups: the control group (C), with vines managed according to tradition, with at least two seasonal toppings, and the treated group (T) with non-topped vines. For both groups, the density of the canopy was evaluated through the adaptation of the “point quadrat method” to the pergola training system. T plants (non-topped) showed a significantly higher leaf area, almost double as compared to the control group that presented a higher sun exposure of the clusters and lower leaf density. Following analysis with an IRGA infrared gas analyzer Li-Cor 6000, T plants showed a better use of water and a higher water use efficiency with significantly lower values of net carbon dioxide assimilation, of stomatal conductance and transpiration rate, compared to the traditional canopy management group, with two toppings during the season. In the first phase of ripening, since véraison, the non-topping approach influenced the berry metabolic composition, suggesting an acceleration of the ripening process as the sugar content and the weight of the berry were higher and titratable acidity was lower respect to the topped vines.

Berry skin hydroxycinnamates and, above all, flavonols were tendentially higher in the more exposed berries of C vines but at harvest, no major differences were found between treatments. Berries collected from non-topped plants showed lower accumulation of glyosidic terpenes but, also in this case, no major differences were found at harvest.

The reduced management of the canopy did not reduce the fertility of buds in the following season. Therefore, in seasons with climatic conditions similar to those of 2023 (high maximum temperatures, good daily temperature ranges and abundant but not excessive rainfall), non-topping of canopy can be an effective agronomic strategy to reduce the management costs and the vineyard management impact, without influencing berry quality, yield and the next- season bud fertility. The optimized water use efficiency did not significantly alter the analytical characteristics of grapes and contributed to economic savings.

References

Vitali, M. Tamagnone, M. La Iacona, T. Lovisolo, C. (2013) Measurement of grapevine canopy leaf area by using an ultrasonic-based method. Journal International des Sciences de la Vigne et du Vin, 47 (3), 183-189.

Kedrina-Okutan, O. Novello, V. Hoffmann, T. Hadersdorfer, J. Occhipinti, A. Schwab, W. Ferrandino A. (2018). Constitutive Polyphenols in Blades and Veins of Grapevine (Vitis vinifera L.) healthy leaves. Journal of Agricultural and Food Chemistry, 66, 10977−10990. ISSN 00218561. https://doi.org/10.1021/acs.jafc.8b03418

Di Stefano, R. Maggiorotto, G. (1995). Anthocyanins, hydroxycinnamic acids and flavonols in berries, leaves, stems and shoots of vine. Riv. di Vitic. e di Enol., 51−65.

Cabrita, M. J., Costa Freitas, A. M., Laureano, O., & Di Stefano, R. (2006). Glycosidic aroma compounds of some Portuguese grape cultivars. Journal of the Science of Food and Agriculture, 86, 922–931.

Acknowledgments

Authors acknowledge the VITIMOUNT Project financed by CRT Foundation, Protocollo:2022.AI1356.U1556CRT.