Comparison of central and northern European winter rye cultivars grown at high latitudes

Finnish rye (Secale cereale L.) cultivars are extremely tolerant of freezing and are fairly resistant to low-temperature fungal infection. Finnish cultivars usually have long straw, are lodging-sensitive, low yielding and have low Hagberg falling number. Many central European rye cultivars have been bred to overcome these problems, but are less winter hardy and have lower yield stability under northern conditions. In the present study, the development and growth of Finnish and foreign rye cultivars were compared in the field and also under simulated average autumn hardening conditions in a growth chamber. Leaf elongation, but not tillering, of both Finnish and foreign rye cultivars ceased during the simulated hardening period in the growth chamber. At the end of the hardening period, both Finnish and foreign cultivars had reached equal dry weights and soluble sugar contents of crowns and leaves. It was concluded that in a typical Finnish autumn, the foreign and domestic cultivars responded similarly when development and hardening were monitored. Thus, the risks related to overwintering are likely to be emphasized under adverse conditions either in the autumn or in the spring. In the field, a German hybrid cultivar performed better than a Finnish population cultivar under favourable growing conditions, but when stresses such as drought occurred, it lost its superiority. When low seeding rates were used, the Finnish cultivar compensated through tillering more efficiently than the German one for the reduced number of main shoots. However, the yield potential of the German cultivar was, in general, higher irrespective of seeding rate. This was due to a higher photosynthesis rate, larger harvest index and grain size.