9. Balance of nitrogen and phosphorus between the vegetative mass and grain in barley varieties and lines

The accumulation, translocation and reutilization of nitrogen and phosphorus were studied in nine Bulgarian malting barley genotypes – three varieties (Krami, Krassen, Kristi) and six new perspective lines (70412296; 2390300; 24102400; 24201900; 689069970; 22506999). It was found that they accumulated the basic part of the total nitrogen in maturity during the pre-anthesis period and are characterized by nitrogen gain in the period after heading/anthesis. The part of nitrogen taken up prior to anthesis was 59,1%–65,1% of the total barley nitrogen at maturity and it hardly depended on the genotype. The pre-anthesis accumulated phosphorus out of the total phosphorus uptake at maturity depended on the genotype and it was in the range 53,7%-96,6 % (and up to 100 % in the lines with a negative post-anthesis uptake – 24201900, 689069970 and 22506999. The varieties and lines reutilized 7,5 kg N/da and 4,67 kg Р2О5/da on average, and the translocation efficiency was 50.6 % for nitrogen and 52.1% for phosphorus. The contribution of the redistributed vegetative nitrogen and phosphorus to the grain was 63,2% for nitrogen and 67,5 % for phosphorus on average. The Krami and Krassen varieties and line 2390300 could be recommended as perspective for the nitrogen reutilization efficiency and line 22506999 was effective with regard to both nitrogen and phosphorus translocation.