Vernalization requirements of bread winter wheat varieties

Aim. To study the peculiarities of vernalization requirement in set of bread winter wheat varieties.Material and methods. The duration of vernalization requirement in bread winter wheat varieties was determined at spring sowing winter wheat with preliminary vernalization of seeds in Petri dishes for 10 to 60 days at temperature of 1–2°C. Vernalized seeds were sown in the soil to5 cm depth (80 seeds per linear meter). In each variant, field germination was determined (%), heading date was noted, number of productive stems was counted at the time of harvesting. To determine the possible additional vernalization in the field, sprouted, but not vernalized seeds of each variety were also sown. Period of vernalization was considered to be sufficient for the variety if most of the plants formed ear.Results. Data obtained show that 51% of varieties had vernalization requirement of 10 to 30 days. Fewer varieties (31%) needed vernalization during 30-40 days and only 18% needed more than 40 days. We have identified the varieties with high vernalization requirement (over 40 days), including Myrleben, Monotyp, Ekspromt, Myronivska 66, Myronivska 28, Volodarka, Khurtovyna, Bohdana, Smuhlianka, Slavna, Dostatok.It has been established that with increasing exposure of the germinating seeds in a refrigerator to 60 days the field germination significantly decreases. At the same time, significant varietal differences were also revealed. Therefore, when sowing in late terms, it is necessary to take into account these peculiarities and to choose varieties which germinating seeds, if left in the soil for a prolonged period, reduce the field germination less.The longest vernalization period (over 60 days) for the years of research was revealed in the variety Monotyp. The variety Voloshkova being created by means of multiple individual selection from plant population obtained by changing growth habit of spring wheat Flambard (France) into winter wheat has low vernalization requirement and high winter hardiness (8 points). Such properties allow using Voloshkova variety for sowing in permissible and late calendar periods. Seeds of varieties Voloshkova, Remeslivna, Pamiyati Remesla, Kolos Mironivshchyny, Lehenda Myronivska, Myrliena, Yuviliar Myronivskyi significantly less reduce the field germination when vernalized within 50–60 days.Conclusions. To assess varieties more objectively along with index of frost resistance, in their characteristics it is expedient to indicate the vernalization requirement. When sowing winter wheat in acceptable and late calendar periods, it is necessary to use varieties with a short vernalization period and frost resistance of at least 7–8 points.