INVESTIGATIONS ON THE COMPONENTS OF WINTER HARDINESS IN FRUIT PLANTS

Modeling of major winter stresses for middle zone of the USSR /artificial freezing tests after standard hardening and dehardening/ let us during 3 years estimate winter hardiness of 32 apple cultivars with probability of 90 %. In breeding program for winter hardiness in fruit plants the method of controlled types of stress may be applied at some stages: choosing donors of specific components of winter hardiness from genofond of genus or species: estimation of hybrid material on 1–2 years old seedlings and after the onset of fruiting.

Up to now severe winters are routine tests of winter hardiness of plants.
As a result of prolonged investigations one usually selects genotypes which are resistant to the complex of unfavourable factors of a local climate. the most promising way of accelerating the forecasting of resistance is modeling winter stresses under controlled conditions.

Recently, suggested as far as in 1947 /Brierley, 1947/ has been realized Brieley’s idea about complexity of winter hardiness.
It was confirmed experimentally that winter hardiness is a multicomponent property of plants.
Laboratory freezing programs in breeding must include the main winter stresses of the climatic zone, reflect the time of action and the role of damaged tissues and organs for the survival of a fruit tree /Gogoleva, Tyurina, 1966; Mittelstadt, 1968; Stushnoff, 1972; Tyurina, 1976/.

Frost is the major injury factor both in severe and mild winters in the middle zone of the USSR. Killing of tissues in fruit trees may occur at any time of the cold period: during early frosts, severe prolonged frosts in

Symposium on Winterhardiness in Woody Perennials

G.A. Gogoleva, A.M. Mikheyev, M.M. Tyurina, V.P. Smagina, N.V. Yefimova

https://doi.org/10.17660/ActaHortic.1978.81.14