The effect on low-temperature resistantance of dormant buds and bud fertility of brined vine leaves harvest at Narince grape cultivar

Narince is the most grown grape variety in Tokat region. Both leaf and grape of Narince are commercially evaluated in this region.The spring and winter frosts cause damage in some years.In this study conducted in 2015 and 2016, it is aimed to determine the effects of picking frequency of brine vine leaf in Narince cultivar on shoot development, winter bud fertility, and low-temperature resistantance of dormant buds were aimed to be determined. In the first year, vine leaves were collected at four different levels (0, 2, 4 and 6 periods). In the second year, cutting weights, diameters, length, dry matter rates, bud fertility and low-temperature tolerance datas were determined in vine cane.In treated grapevines, bud fertility were examined on the basis of 10 nodes for their positions by shooting method in the stratification room.Frost tests in winter buds were carried out in Thermal Analysis Laboratory of Atatürk University, Faculty of Agriculture, Departmentof Horticulture.The cutting samples for frost test were taken de-acclimation phases. Frost tolerances of winter eyes were tested according to Differential Thermal Analysis (DTA) procedures. High temperature exotherm (HTE) and low temperature exotherms (LTE) were determined by DTA method in winter buds.The control and six times leaf picking practices affected bud fertility, dry matter rate, frost tolerance level negatively. Highest number of clusters was detected in the 5th and 6th (1.375 and 1.475 clones / node) nodes.Two and fours leaf picking practices have affected positively the bud fertility and frost tolerance of winter buds. The first 4 eyes in basal were more tolerant to the frost. It was determined the average cutting weight, length and diameter in 10-noded cuttings ; 64.12 g - 44.15 g; 74.89 cm-64.00 cm; 8.81 mm-7.71 mm,respectively. The average number of clusters in buds ranged from 1.215 (2 times leaf pickings) to 0.97 (6 time leaf pickings).According to DTA analysis results, mean LTE50 values in winter buds (death temperature) ranged from -8.34 ° C (6 time leaf pickings ) to -9.36 ° C (4 time leaf pickings). It was determined the minimum HTE value for winter buds was control (-3.65 C) and six time leaf pickings (-4.51° C); maximum HTE values were close to each other in leaf collection applications (-11 ± 1 °C). As a result, it is suggested that leaf picking at maximum of 3-4 times in terms of shoot development, bud fertility and frost tolerance of winter buds.