Dynamics of the concentration of carbon and nitrogen compounds in the productive type of spring barley

During the growing seasons of 1982 to 1988, the above-ground parts of two short-stemmed (60 cm) and a set of medium-stemmed (70 to 80 cm) genotypes of most productive spring barley were studied for dry matter output and contents, total soluble sugar concentrations (c.C), nitrate nitrogen (n.N), ammonia nitrogen (a.N) and total nitrogen (c.N), for nitrate reductase activity (NR), and the physiological and yield parameters. From the end of shooting to early anthesis, the dry matter weight of a single plant increased from 1.8 to 4.9 g; at the stage of milk ripeness it was then as 7.7 g. From the stage of full tillering to milk ripeness the content of dry matter increased, on an average, from 12.7 to 30 per cent and the c.C concentration increased from 124 to 240 mg per g of dry matter; the concentrations of a.N declined form 0.95 to 0.62 mg, n.N from 3.1 to 0 mg, and c.N from 53 to 13 mg per g of dry matter; NR activity declined from 0.068 to 0.018 mg of nitrite nitrogen per 1 g of leaves per 1 hour. The highest variability (per cent) between years was recorded in n.N (23-144), in NR activity (6-77) and in c.C (25-50) and the lowest in a.N (4-20) and c.N (8-24). Grain yield reached 7.5 t per ha at a stand density of 180 to 200 plants with 16 600 grains per 1 m2, with a 1000 grain weight (TGW) of 45 to 46 g, harvest index (per cent) of 50 to 52.6, crude protein content in grain of 10.4 to 11.3 per cent, and nitrogen redistribution between grain and straw of 2.5 to 2.7. The coefficients of variation between the years ranged as follows: grain yield 3 to 9 per cent, number of plants 3 to 11 per cent, TGW 2 to 8 per cent, harvest index 5 to 7 per cent, protein content 10 to 11 per cent and nitrogen redistribution 22 to 36 per cent. Emphasis is laid on the importance of attaining these levels of the parameters during the growing season for achieving the potential productivity of spring barley and for providing an optimum nitrate content and quality.