Browsing by Author "Tarim, Guzin"

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Effect of Foliar Spraying of Ascophyllum Nodosum Extracts on Grape Quality of 'tarsus Beyazi
(Springer, 2022) Topuz, Hasan; Keskin, Nurhan; Kiraz, Mehmet Erdem; Tarim, Guzin; Topuz, Fatih; Ozel, Nurcan; Kaya, Ozkan
In recent years, studies have shown that seaweed applications could prevent post-harvest berry drops in grapes and allow improvements in cluster and berry quality characteristics. This study was conducted on 'Tarsus Beyazi' grape cultivar, which was grown on its own root and goblet-trained, in the Tarsus district of Mersin Province, Turkey. Although 'Tarsus Beyazi' is an early and well-known cultivar, it does not attract much attention due to its genetic susceptibility to berry drop; however, it is an important grape genetic source. In this study, foliar spraying of seaweed (Ascophyllum nodosum [L.] Le Jolis) was applied to the vines of 'Tarsus Beyazi'. After the application, the force to separate the berries from the stalk, berry weight (g), berry width (mm), berry length (mm), cluster width (cm), cluster length (cm), cluster weight (g), titratable acidity (%,TA), total soluble solids (%,TSS), and pH, as well as leaf and berry mineral content, were determined. Based on our results, it was determined that seaweed application had positive effects on the cluster characteristics rather than the berry properties of the 'Tarsus Beyazi'. The difference between application and control grapevines was found to be significant for cluster width and weight. As compared to the control grapevines (11.16 cm), clusters were approximately 9.86% wider in the application grapevines (12.26 cm), and the difference in cluster weight was about 37 g between the mean value of the application (297.40 g) and the control (260.23 g) grapevines. To sum up, the use of seaweeds in 'Tarsus Beyazi' has made it possible to improve grapevine productivity and enhance berry quality, mostly in terms of cluster characteristics.
Timing Matters, Not Just the Treatment: Phenological-Stage Effects of Seaweed and Ethanol Applications on Postharvest Quality of 'Tarsus Beyazı' Grapes
(Mdpi, 2025) Tarim, Guzin; Karakus, Sinem; Keskin, Nurhan; Hatterman-Valenti, Harlene; Kaya, Ozkan
In the context of increasing consumer demand for high-quality, residue-free fruits and the growing emphasis on sustainable postharvest technologies, identifying effective, eco-friendly treatments to maintain grape quality during storage has become a critical focus in modern viticulture. Over the course of this study, we examined the influence of seaweed extract (derived from Ascophyllum nodosum) and ethanol-based postharvest treatments on the postharvest quality of the 'Tarsus Beyaz & imath;' grape. The seaweed extract was applied at six specific phenological stages according to the BBCH scale: BBCH 13 (3rd-4th leaf stage, 0.40%), BBCH 60 (first flower sheath opening, 0.50%), BBCH 71 (fruit set, 0.50%), BBCH 75 (chickpea-sized berries, 0.50%), BBCH 81 (start of ripening, 0.60%), and BBCH 89 (harvest maturity, 0.60%). After harvest, grape clusters were subjected to four different postharvest treatments: untreated control, control + ethanol (20% ethanol immersion for 10 s), seaweed extract alone (preharvest applications only), and seaweed extract + ethanol (combining both preharvest and postharvest treatments). Grapes were stored at 0-1 degrees C and 90-95% RH for three weeks, followed by a shelf-life evaluation period of three days at 20 degrees C and 60-65% RH. The findings revealed that seaweed treatments, especially when applied during cluster formation and berry development, effectively mitigated physiological deterioration, preserving stem turgidity and enhancing berry firmness. In contrast, ethanol showed variable responses, occasionally exerting negative effects, with only marginal benefits observed when applied at optimal developmental stages. Both the type and timing of application emerged as critical determinants of key quality attributes such as weight loss, decay incidence, and must properties (TSS, pH, TA). Correlation and heat map analyses indicated the interrelationships among these parameters and the differential impacts of treatments. These results suggest that phenological-stage-specific seaweed applications hold significant potential as a sustainable strategy to extend the storage life and maintain the market quality of 'Tarsus Beyaz & imath;' grapes.