Abstract
The study was conducted during the period 2017 – 2018 at the Agricultural Experimental Station – Khan Krum, Shumen region. The experimental orchard was established in the spring of 2011. The following nectarine cultivars were studied: Fantasia, Golden Grand, Morsiani 51, Cassiopeia and Fairlane grafted on a seedling rootstock (Elberta) and clonal GF 677, as well as the frost – resistant dessert-type cultivar Redhaven. In the period 2017 – 2018, negative temperatures were reported, at the end of March and at the beginning of April (-3.6°C and -5.0 °C respectively)which coincided with the full blooming phenological phase; as a result of which the blossoms froze (76 – 100%). A relatively low percentage of frozen blossoms was observed in cultivars grafted on rootstock GF 677. In 2017, the blossom damage was relatively low and yields were obtained, unlike in 2018. Negative spring temperatures had a negative impact on productivity if blossom damage percentage exceeded 80%.