Rapid evaluation of frost resistance of plum cultivars

The possibility of early diagnostics of the main characteristics of winter resistant plum cultivars of first year has been proved. It is the resistance to early (November) frosts and low temperatures in fate winter after thaw. It is found that RNA/DNA ratio in apical buds of one year shoots should be used as the criterion of rapid evaluation of plum cultivar (or hybrid seedlings) resistance to early and return frosts. The main index of plum cultivar resistance to return frosts is the change of fructose content in buds of one year shoots under the influence of low temperature. As a result of this evaluation the following local plum cultivars are considered to be very perspective for use: 'Kabardinskaya Rannyaya' (resistant to early frosts) and 'Kubanskaya Legenda' and 'Kavkazskaya Prune' (resistant to return frosts).