Bayraktar, Tuba UzunAygül, GülcanUyak, Cüneyt2024-12-242024-12-2420242618-6578https://doi.org/10.47115/bsagriculture.1521171https://search.trdizin.gov.tr/tr/yayin/detay/1280768https://hdl.handle.net/20.500.12604/5001This study was carried out on the Yuvarlak Çekirdeksiz grape variety cultivated in Siirt University Implementation and Research Vineyard. Four different doses of liquid seaweed extract was applied at three different periods (control -0 ppm; 1st application period (before flowering) - 1000 ppm; 2nd application period (before flowering + after flowering)-1000 ppm + 1000 ppm = 2000 ppm; and 3rd application (before flowering + after flowering + veraison) -1000ppm + 1000 ppm + 1000 ppm = 3000 ppm). The effects of seaweed application on phenological stages and Total Effective temperature (TET) of Yuvarlak Çekirdeksiz grape variety were compared. When the plants with seaweed applications at different phenological periods were compared with the control, it was observed that plants with the first application period had a full flowering phase three days earlier and the veraison phase six days earlier. The Total Effective Temperature value between full bloom and veraison was determined to be between 659.78-819.98 day-degrees (dd), and it was determined that applying seaweed before flowering shortened the vegetation period compared to the control. In contrast, the other two applications extended the vegetation period.eninfo:eu-repo/semantics/openAccessSeaweedPhenological observationsVegetation periodArticle76657663128076810.47115/bsagriculture.1521171