Cold hardiness degrees of some Vitis vinifera L. and Vitis labrusca L. cultivars grown in temperate climate condition

In this study, the cold hardiness degrees of the main grape cultivars grown in the temperate climatic conditions of Samsun province, Turkiye were determined using the tissue browning technique. Winter canes were prepared as single nodes cuttings in the coldest month of February. After an artificial freeze test, LT50 degrees of primary, secondary, tertiary buds, and phloem tissue were determined. In addition, after the freeze test, some growth and rooting parameters of single-bud cuttings were examined in a growing room condition. The highest LT50 values in primary, secondary, and tertiary buds were observed in 'Karaerik', 'Alphonse Lavallee', 'celiksu' and 'Merzifon Karasi' cultivars. Highest primary bud LT50 values were obtained as - 24.3 1 degrees C in 'Karaerik', - 23.1 1 degrees C in 'celiksu', - 22.9 1 degrees C in 'Alphonse Lavallee', and - 22.1 1 degrees C in 'Merzifon Karasi' cultivars. The lowest primary bud LT50 values were found in 'Narince', 'cavus', and 'Trakya Ilkeren' cultivars ( - 11.0 1 degrees C, - 12.1 1 degrees C, and - 16.1 1 degrees C, respectively). While phloem viability rate was 77.3% in 'celiksu', it was determined as 8.0% in the 'cavus' cultivar. The highest primary, secondary, and tertiary bud viability was determined in the 'Karaerik' cultivar (64.7%, 67.3%, and 68.0%, respectively). On the other hand, the least bud viability rates were obtained in 'cavus', 'Narince', and 'Trakya Ilkeren' cultivars. In the growing room condition, the highest mean bud burst (60.7%), bud sprouting ratio (61.0%), and cluster number per shoot (0.42 cluster) were obtained in the 'celiksu' cultivar in growing room condition. The highest mean shoot length (4.8 cm), rooting ratio (59.3%), root length (4.10 cm), and root scale (1.19) were determined in the 'Karaerik' cultivar among freeze applied cuttings.