Dobrudzha Agricultural Institute (DAI) is the largest breeding center for cereals in Bulgaria. Among the varieties developed here, 36 genotypes were included in the national list, a large part of them being strong and medium strong wheat cultivars with increased strength. It is a disputable question if a plateau has been reached in the breeding of wheat and what are the further methods for increasing of the production potential. Until recently, the increasing of the spike productivity lay at the basis of the breeding strategy, primarily through a higher number of florets and grains formed per spikelet at the expense of a lower number of productive tillers. The contemporary high level of breeding and the market requirements impose the necessity to search for new approaches to increase productivity.

The aim of the investigation was to characterize the structure of the yield in new common winter wheat accessions included in the gene pool of DAI. The investigation was carried out during 2015 – 2019 and encompassed four growth seasons with different combinations of meteorological factors allowing for good differentiation. The trial was designed in two replicates, the size of the harvest plot being 10 m2. Sixty-six accessions from different ecological and geographic origin and with specific combination of the economically important traits were evaluated. The cultivars from France were with the highest coefficient of tillering, followed by the cultivars from Croatia and Germany. The variability with regard to 1000 kernel weight was considerable. The Bulgarian and Serbian accessions were with the highest absolute weight, and the French ones – with the lowest. The differences with regard to the number of grains in spike were significant at a high level, but in the separate group, Athlon (DE), Moison (F), Fani (BG), Fidelius (AT), Iveta (BG) Korona (BG) and Simonida (RS) were with high values of the trait. Within the period, the Bulgarian cultivars, which realized highest yield, were Rada and Dragana, and among the European ones, these were Andalou, Basmati, NS 407 and Sofru.