G. Delchev, N. Georgieva, I. Nikolova
Abstract. With the purpose to study the stability of mixtures among preparations with different biological effect on the basis the grain yield in spring vetch a three-factor field trial was carried out during the period 2007-2009 in Institute of Forage Crops, Pleven using the split plot method. Factor A includes the three years of the research. Factor B (preparations) includes 8 levels: untreated control, Atonic (growth stimulator) – 600 ml/ha, Masterblend (combined leaf fertilizers) – 1.6 kg/ha, Atonic + Masterblend, Confidor (insecticide) – 150 g/ha, Confidor + Atonic, Confidor + Atonic + Masterblend, Confidor + Masterblend. Factor C (stages of treatment) includes three levels: budding, budding + flowering, flowering. The most stable mixtures with regard to the grain yield are Atonic + Masterblend and Confodor + Masterblend, and with single use of preparations – the insecticide Confidor. Technologically valuable mixtures which match high stability and high productivity in the different years are all combinations with twofold application at budding and flowering and with the best parameters are distinguished the combinations Confidor + Atonic and Confidor + Masterblend. The single treatment at flowering stage should be avoided because of reduced productivity independently that it is characterized with high stability during the different years.