Radiation-use efficiency of modern and old spring cereal cultivars and its response to nitrogen in northern growing conditions

The typical features of high latitude growing seasons, particularly the short and intensive growth period and intense solar radiation during early growth, limit crop development and yield formation. A field study was conducted over two years to assess the differences between old and modern spring cereal cultivars in radiation-use efficiency (RUE), to characterise the traits contributing to the differences and to gauge the effect of nitrogen on the traits. Field experiments were conducted with wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and oat (Avena sativa L.) under two nitrogen regimes (90 kg N ha−1 and control with 0 kg N ha−1). RUE was reduced at 0 kg N ha−1. Pre-heading RUE was not influenced by year, but post-heading RUE was, with values being either higher or nearly the same in comparison with pre-heading values. RUE values for barley, wheat and oat were similar to those reported elsewhere. Old two- and six-row barley cultivars had higher pre-heading RUE than modern cultivars. After heading, under decreasing light levels biomass accumulation was high due to the high RUE values. Old oat and six-row barley cultivars had higher post-heading RUE than modern cultivars. In intensive northern growing conditions, RUE varied seasonally and increased at increasing N application rate.