This contribution summarizes our knowledge on more complex cases of inheritance of the traits thât affect the yield indirectly and that are of breeding and seed growing importance. Further on, it summarizes knowledge of genetic parameters of yield traits and results of their variability evaluation. Following traits are dealt with: pollen sterility conditioned by 4 genes, recessive ramification determined by 2 genes and dominant ramification determined also by 2 genes, head inclination conditioned by 12 genes. Genetic characteristics of the following polygenic traits are described: oil content and husk of achenes, weight and number of achenes, plant height and leaf area, self-fertility. ln the yield components directional coefficients and variability as the proportion of additive and non-additive components of inheritance are presented.