Cold and winter resistances of different oil seed canola hybrids and possibilities for reseeding of damaged by frost crops

G. Delchev*

Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

Abstract. In 2010 – 2012 a field experiment was conducted. A total of 8 hybrids of winter oil seed canola (Brassicanapus L.) were investigated: 2 Clear Field hybrids – PT200CL and Sunset; 1 Clearfield Maximus hybrid – PX100CL; 4 conventional hybrids – PT205, Rohan, Exagonand Nelson; 1 conventional Maximus hybrid – PR44D06. On fields with damaged by frost winter canola the following were sown in spring and investigated: 2 conventional hybrids spring oil seed canola – Zhura and Williams; 1 cultivar of durum wheat (Triticum durum Desf.) – Elbrus; 3 hybrids oil-bearing sunflower (Helianthusannuus L.): 1 conventional hybrid – Arena, 1 Clearfield hybrid – Allego and 1 Express Sun hybrid – P64LE20; 2 hybrids grain maize (Zeamays L.): 1 cool resistance conventional hybrid – Novatop and 1 Duo System hybrid – Blazon duo; 1 hybrid grains orghum (Sorghumbicolor Moench.) – Alise. Winter canola Clearfield hybrids PT200CL and Sunset, Clearfield Maximus hybrid PX100CL, conventional hybrids PT205 and Rohan and conventional Maximus hybrid PR44D06 winter successfully despite the adverse weather conditions, due to the very good cold and winter resistance and the applied chemical treatments. Through some agricultural activities adverse weather conditions can be reduced to anacceptable minimum. Seed yield of spring oil seed canola hybrids Zhura and Williams with optimal sowing densities are lower than the yields of winter hybrids Exagon and Nelson with minimum sowing densities. Hybrids with minimum density of 15 plants/m2 are recommended to harvested crops of winter canola in stead of being resowed with spring canola hybrids. After ploughing the fields with damaged by frost winter canola hybrids spring durum wheat should not be planted. After ploughed canola crops it is appropriate to sowimitolerantortribenulon-methyltolerantsunflower hybrids instead of conventional sunflower hybrids. After ploughing canola the more weeded fields should be sown with cycloxydim tolerance maize hybrids and the less weeded ones – with conventional maize hybrids. Grains or ghumgrown by the Concept technology is a suitable crop for sowing on fields after damaged by frost winter canola.