In 1998–2000, in a multi-factorial field experiment established by the method of split blocks and subplots, we studied the effect of three systems of beet tops management, two sowing rates and two levels of N fertilization and the effect of interactions of the factors on production and qualitative indicators of spring barley varieties Amulet and Kompakt. The evaluation shows the dominant effect of the particular year on the variability of all characters. The proportion of the effect of the year on the variability of characters ranged from 2.1 (number of plants per m2) to 80.1% (yield). The variability of quality parameters was also considerably affected by the genetic factor of the variety (grain over2.5 mmsieve 40.4%, TGW 20.5%). The level of characters was greatly variable in relation to the course of climatic conditions of the year. The highest grain yield was achieved in 1999 (7.21 t/ha), the lowest one in 2000 (5.25 t/ha). The best quality parameters were shown by grain from the 1998 harvest (yield 6.20 t/ha) with significantly highest TGW (47.76 g), a high proportion of grain over2.5 mmsieve (92.01%, 5.54 t/ha) and a favourable content of N substances in the grain (10.60%). Ploughed down beet tops supported the creation of the yield, the average differences between variants were, however, minimal being heavily affected by the course of weather in particular years. More favourable conditions for the creation of the yield (6.17 t/ha) and for the formation of mechanical properties of the spring barley grain (TGW45.55 g, grain over2.5 mmsieve 85.86%) were produced by variants with late ploughing down beet tops, the smallest accumulation of N substances occurred in variants with harvested beet tops (11.83%). Sowing rate significantly affected values of all studied characters. Variants sown 4.5 MGS (6.27 t/ha) gave higher average grain yields, grain of better quality was obtained from the stands sown 3.5 MGS (TGW45.22 g, grain over 2.5 sieve 84.41%, N substances 11.93%). Between particular varieties, significant differences were found both in the economic yield and the grain quality. The Kompakt variety showed on average 4.7% higher yield (6.37 t/ha) than the Amulet variety which, however, reached the higher average TGW values as well as the proportion of grain over2.5 mmsieve (45.87 g, 88.24%). The grain quality of the Amulet variety was negatively affected by the increased accumulation of N substances in the grain (12.49%). As compared with control, N fertilization at the rate of 30 kg/ha showed significant increase in the yield in 1998 only (by 7.5%) while in other years, an increase in the yield was not noticed. In all years under investigation, the TGW values and the proportion of grain over2.5 mmsieve decreased and the content of N substances in grain increased after application of N at the rate of 30 kg/ha.
The p-coumaroyl arabinoxylan transferase HvAT10 underlies natural variation in whole-grain cell wall phenolic acids in cultivated barley
