S. Vulchinkov*, V. Valkova, D. Ilchovska, P. Vulchinkova
Maize Research Institute, 5835 Kneja, Bulgaria
Abstract. Two maize hybrids Kn 619 and Kn 517 with different ratios of CMS plants – C and M types (33%, 50% and 66%, respectively) are tested in 2 plant densities for 4 year period (2009–2012) in Maize Research Institute, Kneja. ANOVA results show significant variances for environments and variants of hybrids but G x E is not significant. In the variants with different CMS proportions as an average from all environments exceedings of grain yield to fertile checks are observed in both hybrids at a ratio 50% sterile plus 50% fertile plants, better expressed at Kn 619 (102.5%). These exceedings are best observed in 2009 – 3 of all variants, and one for 2010 and 2012. Another trait observed – 1000 kernels weight (MVK) has the same tendency, well expressed for Kn 619. The combination of free pollination effect (xenia) and the weakened competition of plants with sterile tassels to their ears in relation to assimilates was called system “Plus”. That system may increase maize grain yield within the frame of accepted practice without additional expenses for farmers. The effect of that system as new technology decision is better expressed in the Kn 619 hybrid.