NITRATE REDUCTASE-ACTIVITY AND PROTEIN-CONTENT IN LEAVES AND ROOTS OF 2 DOUBLED HAPLOID BARLEY LINES DEPENDING ON SEEDLING AGE AND NITROGEN-SOURCE

The lines of doubled barley haploids - C 41 and C 47/1 - differed markedly by nitrate reductase activity in the leaves and slightly, but significantly - in the roots. At 6th and 7th days of seedling growth the activity of nitrate reductase in the leaves was 50% higher in the line C 47/1 than in C 41. Differences in the activity of this enzyme between the lines remained during the succesive days of seedling growth and were independent on the source of nitrogen (KNO3 or NH4NO3) supplied to the plants. The presence of NH4NO3 in the medium in a wide range of concentrations caused stimulation of nitrate reductase activity in seedling leaves, but reduced it in roots. In the presence of NH4Cl in the medium no nitrate reductase activity was found in the leaves of the both lines, whereas trace activity of this enzyme was detected in the roots. The amount of total water-soluble protein the extracts from the seedling leaves and roots was on a similar level in the both lines under study. It is suggested that differences in the NR activity between the studied barley lines may be related to genetic regulation of NR induction.