Frost hardiness of grapevine cultivars as affected by ground cover under Scandinavian conditions
Cultivation of grapevine is novel under Scandinavian conditions. We studied the impact of ground cover on frost hardiness of grapevine cultivars in Northwestern Scania in a two-factorial trial with four cultivars Solaris, Pinot Gris, Siegerrebe, Ortega and three kinds of ground cover (open soil, plastic cover and gravel). The study was conducted in a grapevine orchard, planted in May 2009, in Broddarp on Bjärepenisula Sweden (N latitude 56°; longitude E 12°). Soil and air temperature were monitored continuously.
Frost hardiness measurements were performed every second week from late September to early December 2009. Frost resistance, LT50, was determined by electrolyte leakage measurement of the upper stems after artificial freezing at -15 °C. The results showed that Solaris is the significantly most frost hardy of the cultivars under Scandinavian conditions. Ground covers showed no significant difference with respect to frost hardiness in general.
Buds were visually assessed based on BBCH scale in the beginning of the following season (May 2010). Swollen buds were counted. State of development of buds dependent on ground cover do not differ noticeably. At the time Solaris have the biggest bud growth.