Field crops institute (FCI), 6200 Chirpan, Bulgaria
(Manuscript received 5 September 2019; accepted for publication 18 October 2019)
Abstract. The aim of the study is to investigate the heterosis manifestations in durum wheat for quantitative traits related to spike productivity. Diallel cross includes five modern varieties of durum wheat: Victoria (BG), Deni (BG), Superdur, Progress (BG), Predel (BG). The heterosis manifestations of the ten crosses are traced for the traits: spikelet number per spike, number of kernel per spike, grain weight per spike and thousand kernel weight. The experiment is conducted in the 2014-2016 period in the experimental field of FCI- Chirpan. Standard technology for the cultivation of durum wheat is applied. The trials are organized in a randomized block design with three replications. Of each replication 30 plants are randomly picked and harvested for biometric analysis. The mean values by years from the F1 spike biometric measurements are included in the statistical analysis to determine the mid parent and better parent heterosis. For spikelet number per spike, seven crosses show high parent heterosis in the first year, four in the second and six in the third year. In all years, hybrids with a variety of Victoria have more spikelet number per spike and show better parent heterosis. For the trait kernel number per spike it is observed that combinations with Deni variety in most cases have better parent heterosis. In all years, the cross Superdur x Predel indicates high parent heterosis for this trait. For grain weight per spike most of the combinations exhibit high levels of better parent heterosis. When the Deni variety is used as female parent, all hybrid combinations show high levels of heterosis for the trait grain weight per spike. In regard to the thousand kernel weight different heterosis levels are observed, with only negative values in the first year. In the other two years in hybrid combinations there is positive heterosis in one year and negative in another year. The participation of the Deni variety in hybrid combinations leads to better parent heterosis for this trait. The data allow the use of these crosses directly in the breeding of durum wheat to increase individual traits and/or increase productivity.