Genotypic differences in translocated dry matter and nitrogen of spring barley

Over 2000-2001, plot f ield experiments with spring barley were conducted (in west Slovakia, lowland climatic region, maize/barley-growing region) to investigate the effects of translocated dry matter (DM) and nitrogen (N) on grain yield and the N content of grain. Seven parental varieties and 135 F2.3 lines from 9 crosses in F3 and 5 parental varieties and 42 F2.4 lines from 5 crosses in F4 were analysed for dry matter and grain yield, and in F4 generation also for the nitrogen content in vegetative DM and in grain of 30 genotypes. In 2000 when a period from sowing to heading was 14 days shorter in comparison to 2001 lower biomass yield was produced at heading out of a total DM yield at maturity (for varieties 42.9% and for lines 52.4%) than in the favourable year 2001 (50.8% and 56.9%, respectively). DM translocation was higher in 2001 than in the previous year, but in both years there were high differences in a proportion of translocated grain DM between varieties and lines. In 2000, this proportion ranged from -32.3% to 14.7% in varieties and from -14.0% to 24.8% in crosses while in 2001, in the same order, it varied from -13.3% to 33.1% and 6.2% to 23.8%. Genotypes with a higher portion of translocated DM in grain had a lower grain yield in comparison with those producing from heading to maturity a higher amount of assimilates, which exceeded the need for grain formation. Selection for greater biomass yield can be indirect selection for grain yield. Differences in the nitrogen content of vegetative biomass at heading and maturity between varieties were manifested in crosses as well as in relative effectiveness of N translocation (a ratio of vegetative biomass nitrogen content at heading to straw nitrogen content at maturity) and that of nitrogen utilization (a ratio of grain nitrogen content to straw nitrogen content). High relative effectiveness of translocation was found in the Progres variety and the SK13-9 genotype and in the 6-Progres x Galan cross. High relative effectiveness of N utilization was found in the Progres variety and the SK13-9 genotype. Selection for higher effectiveness of N translocation and utilization seems to be real.