Plant Growing Department, Faculty of Marine Sciences and Ecology, Technical University, 1 Studentska, 9000 Varna, Bulgaria
Abstract. The obtaining of high yields of crops is directly dependent on the cultivated varieties. In their creation it is essential the selected initial breeding material to possess certain qualities that lead to overcoming the effects of biotic and abiotic stress factors. Common winter wheat is characterized by great diversity of possibilities for combining initial breeding material due to phylogenetic similarity to many species of the genera Triticum, Aegilops, Secale. In creation of synthetic hexaploids (2n = 6x = 42, AABBDD), the choice of tetraploid component involved into the crosses is very important. The species Triticum polonicum (2n = 4x = 28, AABB) possesses many valuable features related to its protein content, resistance to brown rust, powdery mildew and septoria leaf blight, but it is susceptible to varying levels of black rust attack. This is a prerequisite a correlation between the attack of the pathogen and some spike indicators that correlate with grain yield to be searched. To determine the relationship between the attack and the specific parameters, 52 accessions of the species Triticum polonicum have been studied in the financial 2012/2013 year, to the following indicators: length of spike, length of spike with awns, number of spikelets, weight of spike, weight of grains per spike, number of grains per spike, weight of 1000 grains, weight of spike after threshing. An evaluation of the infectious type of black rust attack on each accession is recorded according to 9-point scale, and correlation with the average values of each of the spike indicators is reported. To neutralize the influence of the factor ‘accession’ two specific indexes are calculated as a corrected value of the weight of 1000 grains. The highest and significant correlation was observed between the infectious type and both specific index (-43.2% and -44.6%), and less with the weight of 1000 grains (-41.9%). Insignificant or unreliable is the correlation of the other spike indicators with the infectious type. The lack of reliable and significant correlation of pathogen attack with the weight of grains per spike as an essential element of the yield, gives rise to claims that Triticum polonicum possesses a compensatory mechanisms to the effect of the black rust. This determines most of the studied accessions as a potential initial material for the creation of synthetic wheat or for inclusion into the selection programs of winter wheat.