8th INTERNATIONAL WHEAT CONFERENCE

meThodS of WINTeR hARdINeSS TeSTS IN BReedINg of
WINTeR WheAT IN ukRAINe
V. Ryabchun and N. Riabchun
Yurjev Plant Production Institute, Moskovskyi prospect, 124, Kharkiv, Ukraine
E-mail Address of presenting author: vicno@mail.ru
Winter hardiness is of utmost importance at winter wheat breeding in the north-eastern
part of Ukraine. It is conditioned by a continental climate of this part of the country,
where fall arid conditions are accompanied with the complex of winter and early unfavorable
periods. The main unfavorable factors of fall - winter - spring period are fall
drought, low negative temperatures, ice crusts, drench, late frost return, spring drought.
In this connection newly developed and introduced varieties of winter wheat must be
resistant to the mentioned factors, especially, such severe as low temperatures and ice
crusts. This resistance more fully ensures the realization of genetical potential of yield of
varieties.
In natural conditions it’s not frequently possible in 1 – 2 years to evaluate forms and
lines’ resistance to low temperature. Therefore the varieties from working collection and
breeding materials are exposed to trials in the control conditions every year by means
of freezing in the low-temperature chambers and then a posterior regrowth in the green
house. Thus a critical temperature of freezing for each tested sample is set. In parallel
these cultivars are grown in field trials. Here they are evaluated for stability to the other
factors like ice crusts, fall, winter and spring drought, drench, snow mould, etc.
It’s also effective to apply the method for plant freezing in bunches (Donskoi method):
the plants go through a hardening process in field conditions, then they are formed in
bunches and they are freezed in low-temperature chambers, regrowth in the green house.
The method is remarkable by its good reliability and high hardening capacity. The freezing
method for seedlings in rolls developed by the researchers of Selection–Genetical Institute
(Odessa) and Plant Production Institute nd. a. V. Ya. Yuryev (Kharkiv) permits for
2 – 2,5 months to evaluate specimen stability to low temperatures as compared with the
varieties – standards and to group them as to the degree of frost hardiness. All operations
made in controlled conditions. This method is less labourous and permits to evaluate a
large set of varieties.
The indirect methods are also used. They classify winter plants according to their ability
to winter hardening. This is such methods as: the dynamics of a content of soluble carbohydrates
in plants’ tillering nodes, the duration of vernalization period. The analysis
of the new introduced varieties of winter bread wheat from the collection of National
Center for Plant Genetic Resources of Ukraine, from Russia, Ukraine, other countries
of Europe and America and of breeding materials has been carried out. All the varieties
were divided into several groups according to a degree of hardiness from 1 to 9 balls
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