Early defoliation positively enhances bioactive composition of berries with no effect on cuticle characteristics
Leaf removal in the fruit-zone has been employed to improve cluster light exposure and ventilation and therefore increase metabolite accumulation and reduce botrytis incidence in berries. When applied before flowering (early defoliation – ED), it can also decrease cluster compactness and regulate yield in high-yielding varieties. This study aimed to evaluate the impact of ED on the physiology and metabolism of Aragonez (syn. Tempranillo) berries along the ripening period. The experiment was set up in 2013 at a commercial vineyard located in the Lisbon winegrowing region. ED was compared to a control non-defoliated (ND). Berry temperature was continuously monitored and normal heat hours (NHH) were calculated. Photosynthetic active radiation at cluster level (PARcluster) was monitored at five phenological stages (green berry (GB), pea size (PS), veraison (VER), mid-ripening (MR) and full maturation (FM). Various berry parameters were monitored: sugars, acidity, wax content, berry permeance, flavonoid compounds, abscisic acid (ABA) and related metabolites. As compared to ND, ED induced ~80% increase in PARcluster, and higher NHH. Consequently, accumulated temperatures above 35ºC were higher in ED than in ND. No differences in anthocyanin compounds were observed at FM, however, in ED the glucoside forms of anthocyanins reached their maximum concentration at MR. A high correlation was found between anthocyanins and NHH (r>0.83, p<0.01) as well as between flavonols and PARcluster (r=0.73, p<0.05). ABA was slightly higher in ND than in ED for the same NHH and after VER, ABA decreased faster in ED than in ND. ABA-GE increased exponentially from VER, reaching its maximum at MR in ND, while in ED it continued to accumulate through FM. Neither the wax content nor the cuticle permeance were affected by the ED treatment. Overall, ED induced changes in cluster-zone thermal and light microclimate which impacted berry ripening metabolism.
Acknowledgements: This research received funding from the European Community’s Seventh Framework Programme (FP7/2007–2013), grant agreement nº 311775, Project Innovine.
Issue: ICGWS 2023
1 Plant Molecular Ecophysiology Laboratory. Instituto de Tecnologia Química e Biológica (ITQB), Universidade NOVA de Lisboa, Oeiras, Portugal
2 LEAF—Linking Landscape, Environment, Agriculture and Food Research Center, Associated Laboratory TERRA, Instituto Superior de Agronomia, Universidade de Lisboa, Tapada da Ajuda, 1349-017 Lisboa, Portugal
3 INIAV – Instituto Nacional de Investigação Agrária e Veterinária, Polo de Inovação de Dois Portos, 2565-191 Dois Portos, Portugal
4 Department of Life Sciences, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal
5 IPSP – Institute for Sustainable Plant Protection, National Research Council (CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino (Florence), Italy
6 DAGRI – Department of Agriculture, Environment, Food and Forestry, University of Florence, Viale delle Idee 30, 50019 Sesto Fiorentino (Florence), Italy