Published in Scientific Papers. Series A. Agronomy, Vol. LVIII
Written by Nedialka YORDANOVA, Lyubena KUZMANOVA, Svetla KOSTADINOVA

The changes in reutilization of vegetative dry mass of barley were studied in dependence of source-sink ratio as aresult of the reduction of spike by half. A malting barley variety Krami was investigated in conditions of long-termfertilizer trial at the experimental field of Department of Agrochemistry and Soil Science of Agricultural University –Plovdiv on soil type Molic fluvisol. It was found that in anthesis the vegetative dry mass was higher than the dry mass ofthe growing spike, and its share of biomass was 31.0% for the first year of study and 31.9%, respectively for the second.The amount of phosphorus in the developing spike was 40.4% and 44.6%, respectively in 2013 and 2014. The reductionof the spike had a low influence on the accumulated straw dry mass but significantly reduced that of the grain, andtherefrom the yield harvest index. As a result of the reduction of spike, the amount of phosphorus in grain was highlyincreased in both experimental years. As opposed to grain, the changes in the content of straw phosphorus in plantswith and without reduced spikes, were less developed. Barley accumulated significant amounts of net dry mass afteranthesis, and a gain of dry mass and phosphorus was established after that phase during the two years of study withhigh values in 2014-up to 67.3% for barley without reduced spikes. A higher efficiency of phosphorus reutilization wasestablished in 2013-61.9%. The barley productivity decreased as a result of the spike reduction with a significantlowering of yield in 2014. A lower productivity was reported in the second year of study as a result of unfavourableweather conditions during the year.

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