T. Nedelcheva*, V. Maneva
Institute of Agriculture, 1 Industrialna, 8400 Karnobat, Bulgaria
(Manuscript received 5 July 2016; accepted for publication 9 September 2016)
Abstract. Over the period of 2014-2015, on the experimental field of the Institute of Agriculture in Karnobat, Bulgaria, was set a field trial with twenty cultivars of barley – 15 two-row: Obzor, Emon, Perun, Orfey, Lardeya, Asparuh, Kuber, Zagorets, Imeon, Sayra, Devinya, Sitara, Krami, Vicky, Potok; 3 four-row: Veslets, Aheloy 2, Tamaris; and 2 six-row cultivars – IZ Bori and Bozhin. All the cultivars were grown in three types of farming: conventional, organic and biodynamic. In conventional farming were applied pesticides and nitrogen fertilization. In the organic production were not used pesticides, mineral and organic fertilizers; and in biodynamic farming was applied biodynamic compost prepared from manure and biodynamic preparations (also organic). In conventional farming, the seeds were disinfected before sowing with Kinto plus (Triticonazole 20 g/l + Prochloraz 60 g/l), at a rate of 150 ml/100 kg seeds. In organic and biodynamic farming were used nondisinfected seeds. In the phenophase of full maturity of barley was conducted monitoring survey for plants infected with loose smut in all the trial variants, the number of infected plants per m2 were counted and the infection rates were calculated. Infected plants of Tamaris grown in the three types of farming underwent microscopic analysis and measurement of 100 teliospores from each variant. The aim of this experiment was to investigate varietal susceptibility of barley to Ustilago nuda, grown in three types of farming, and to establish if the growing method affects the size of the teliospores of the pathogen. With two-row barley were found plants of Lardeya, Kuber, Devinya, Krami and Vicky infected with Ustilago nuda. Krami manifested the lowest resistance in the three types of farming. With four-row barley, Tamaris was found to be highly susceptible and Veslets was poorly resistant. Both cultivars expressed weaker susceptibility in conventional and biodynamic farming and stronger in organic. With six-row cultivars was found no infection. The cultivars of Obzor, Emon, Perun, Orfey, Asparuh, Zagorets, Imeon, Sayra, Sitara, Potok, Aheloy 2, IZ Bori and Bozhin were resistant to Ustilago nuda and are suitable to be grown in the three types of farming. The size of teliospores in organic farming exceeded the ones in conventional farming with 5.28%, and the ones in biodynamic farming were smaller with 0.93% on average. The differences were not proven, but the tendency can be explained with the various approaches in growing the crops.