Row Orientation and Defoliation Effects on Grape Composition ofVitis viniferaL. Agiorgitiko in Nemea (Greece)

Abstract

Abstract. Vineyard row orientation and canopy side exert a significant role in determining grape microclimate. The latter can be further manipulated by selective defoliation in the bunch zone. The aim of this study was to investigate the combined effects of row orientation and basal leaf removal on grape ripening of Vitis vinifera L. cv. Agiorgitiko in Nemea, Southern Greece. The experiment was conducted in 2017, on two adjacent vineyard blocks planted in 1990 on a flat site with two row orientations, North-South and East-West. Both blocks were grafted onto 41B rootstock and trained on a double cordon vertical trellis with uniform vineyard operations. Defoliation treatments included full leaf removal in the bunch zone performed at berry set and a non defoliated control, replicated three times in both blocks. Grapes were sampled at three time points from veraison to harvest from all canopy sides (i.e. E and W on North-South oriented rows and N and S on East-West oriented rows) and defoliation treatments and were analyzed for yield components and berry chemical composition. In addition, approximately 5 kg of grapes were collected from all plots and processed according to a standard winemaking protocol. Total yield and berry mass were lowest in the W-exposed and in the defoliated grapes. Must sugar and acid content, as well as wine alcohol and acidity did not depend on either factor. Skin anthocyanins and phenolics generally increased with defoliation. Skin anthocyanins and total berry phenolics were highest for north-south oriented rows, in the grapes of the cooler canopy side (E). Wines made from grapes of the E and W canopy sides showed the highest wine color, phenolic richness and the lowest pH. No interaction between row orientation and defoliation was detected for any of the measured parameters. According to the results, the E-facing grapes on the north-south oriented rows showed generally a superior grape and wine composition for Agiorgitiko variety, under the semiarid conditions of the Nemea area.

Row orientation effects on Syrah grapevine performance during winter growing season

“…Temperatures above 30-35 °C, otherwise, impairs the accumulation of anthocyanis. In general, the phenolic compounds synthesis is favored by the best sun cluster exposure in NS oriented vines than in other vineyard directions (Chorti et al, 2018). In our study, the best balance between vegetative and reproductive parts may also be involved in the increased anthocyanins and total phenols observed in NS oriented vines.…”

“…On the other hand, EW orientated rows can capture largest portion of total radiation in the cluster zone from soil reflected radiation and leaves of EW orientated vines can also show higher CO 2 assimilation, stomatal conductance and transpiration than NW orientation as showed by Hunter et al, (2016). However, the reduced light interception in EW row orientation may also have a negative impact on growth and yield as compared to NS direction (Chorti et al, 2018).…”

Row orientation effects on chemical composition and aromatic profile of Syrah winter wines

“…The influence of row orientation on alcoholic strength is not clear. Chorti et al (2018) and Hunter & Volschenk (2018) did not find a significant difference between the alcohol content in NS and EW row orientations, although Jogaiah et al (2012) and Souza et al (2019) observed a slight increase in the soluble solids content in berries from an EW row orientation. Jogaiah et al (2012) also found a higher potassium content in the must from an NS row, which could explain higher pH and ashes content in wines from NS-oriented vines.…”

“…On addition, Chorti et al (2018) reported a lower anthocyanin content in wines from EW-oriented rows and higher color and phenolic content values from NS-oriented rows. However, as also observed by Jogaiah et al (2012), the flavonol concentration did not exhibit differences between treatments.…”

“…Dn the other hand, EW-oriented rows can capture the largest portion of total radiation in the cluster zone from soil-reflected radiation, and the leaves of EW-oriented vines can also display higher CD 2 assimilation, stomatal conductance and transpiration than those with a NW-SE orientation, as demonstrated by Grifoni et al (2008) and Hunter et al (2016). However, the reduced light interception in an EW row orientation may also have a negative impact on growth and yield compared to an NS direction (Chorti et al, 2018;Souza et al, 2019). Hunter & Volschenk (2018) observed that some wine sensory descriptors had lower scores for the EW row orientation in comparison with NS wines.…”