Frost hardiness of flower buds of three Hungarian almond cultivars during dormancy

Abstract

Frost hardiness of flower buds of three Hungarian almond cultivars (‘Tétényi Bőtermő’, ‘Tétényi Kedvenc’, ‘Tétényi Keményhéjú’) was investigated by artificial freezing tests during ten dormancy periods. LT50 values were calculated after artificial freezing treatments on different temperatures. Based on the results of regular observations, the frost hardiness profile of three cultivars has been described in each dormancy period. Frost tolerance was significantly affected by year and genotype. The potential frost tolerance of cultivars in our geographical location, in the middle of Hungary, has been characterised by LT50 values in January 2017, as the best values of them. Flower buds of ‘Tétényi Keményhéjú’ were the most frost hardy, its LT50 in this sampling date was -20.5 °C, ‘Tétényi Bőtermő’ was the most sensitive (LT50: -17.6 °C), while ‘Tétényi Kedvenc’ showed intermediate frost hardy (LT50: -19.1 °C). Nevertheless, in mild winters the cultivars were unable to reach their genetically potential maximum frost hardiness. Hungary is situated at the northern part of almond growing area, so frost tolerance of flower buds is one of the most important traits of cultivars. Based on the results of artificial freezing tests the best cultivars can be selected from the aspect of crop safety.