The heritability, phenotypic variability and components of variance for spike length and number of spikelets per spike have been studied in 50 cultivars from different selection centers all over the world. The experiment was performed in randomized block design in three replications on the experimental field in two years. A total number of 60 plants have been analyzed in the full maturity stage. Average estimated values of spike length and number of spikelets per spike differed significantly among years and among cultivars. The highest average value of spike length had Mironovskaya 808 cultivar (V =14.5 cm), and the lowest value was found in Etoille de Choisy (J=8.1 cm) and San Pastore cultivar (V =8.2). During investigated periods the highest average value for number of spikelets/spike had Sava cultivar (V=28.2), and the lowest value expressed Frontana cultivar (V =19.2). The average variation coefficient for spike length was 8.0%, and for number of spikelets per spike was 7.5%. The lowest variability for spike length was established in Pernel cultivar (V=4.8%) and the highest in Lepenica cultivar (V=12.9%). The coefficient of variation for number of spikelets per spike ranged from 4.7% in Bankut 1205 to 12.4% in Norin 10 cultivar. The obtained heritability values in broad sense were fairly high for spike length (96.4%) and number of spikelets per spike (79.1%). Phenotypic analysis of variance indicated that genetic variance took a larger portion of the total phenotypic variability for spike length (81.82%) and for number of spikelets per spike (57.36%) than influence of environmental factors on expressing of analyzed yield components

Oil yield is a major characteristic of each sunflower hybrid (Škorić et al., 2005). To be able to develop new high-oil sunflower hybrids by the method of interspecific hybridization, it is necessary to have information on mode of inheritance and combining abilities of inbred lines used. When selecting prospective lines as components of future hybrids, it is important to know correlations between yield components on one side and oil content on another.Seven new divergent cytoplasmic male sterile lines (A) developed by interspecific hybridization, three Rf-restorer lines used as testers and 21 F 1 hybrids have been subjected to the line × tester analysis. Significant differences have been obtained in mean values for all characteristics under study.Significant differences were found between A lines and R lines on one side and their F 1 hybrids on the other in oil content, plant height, head diameter, total number of seeds per head, 1000-seed weight and seed yield per plant. The line NS-GS-4 exhibited a highly significant positive GCA value for oil content. The line NS-GS-5 had a highly significant negative GCA value for oil content. The hybrid NS-GS-6 × RHA-R-PL-2/1 had a highly significant positive SCA value for oil content. Non-additive component of genetic variance played the main role in the inheritance of oil content, as indicated by the analysis of variance of combining abilities and the analysis of components of genetic variance. Further confirmation was the ratio GCA/SCA for oil content in the F 1 generation which was smaller than unity (0.33). The highest average contribution to the expression of oil content (77.3%) was exhibited by the A lines. Highly significant negative correlations were found between oil content on one side and head diameter, total number of seed per head, 1000-seed weight and seed yield per plant on the other.

The parameters of grain filling and yield components in common wheat (Triticum aestivum L.)

The creation of new sunflower hybrids with high genetic potential for seed yield on the basis of interspecies hybridization requires a possession of the information about the mode of inheritance and the combining abilities of the created inbreed lines for the total seed number per head and the mass of 100 seeds. Apart from this the research of interdependence between yield components and seed yield allows the defining of traits which have the biggest influence on the yield formation. Significant differences were found among the A lines, Rf testers and their F1 hybrids in total seed number per head and the mass of 100 seeds. Analysis of variance of the combining abilities revealed highly significant differences for GCA and SCA. Highly significant positive value GCA was demonstrated by A-line NS-GS-5 for both traits. Hybrid NS-GS-5xRHA-R- PL-2/1 has the highest significant value SCA for both traits. The main role in inheritance of the total seed number per head and the mass of 100 seeds is played by non additive component of the genetic variance which is confirmed by the GCA/SCA relation in F1 generation that is less than one (0.11, 0.24). Rf-testers had the highest average contribution in the expression of the total seed number per head (55.8%) while for the mass of 100 seeds a more significant contribution was given by A-line (70.6%). A strong positive interdependence has been determined between seed yield and total seed number per head (0.37