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Summary The objective of the study was genetic and breeding screening of selected varieties and hybrids of oil flax for in-seed cadmium fixing ability. Seven parental varieties as well as nineteen F1 and F2 hybrids were analyzed. The varieties were crossed in di-allelic scheme, according to the Griffing method II. Significant differences were found in the activity of fixing cadmium from the soil between analysed flax parental forms and hybrids. High variability of tested genotypes, calculated by the variance coefficient, was observed in F1 generation. The variability of tested genotypes in the F2 generation was two times lower. The analysis of general combining ability (GCA) showed that Chinese cultivar Shanxi reduced significantly the fixing cadmium from the soil in combinations of F1 generation crossing. However, the effects of the specific combining ability (SCA) of tested hybrids to reduce the cadmium content in seeds were statistically insignificant. The analysis of genetic components variance showed no significance both in domination and cumulative genes which suggests a complex inheritance pattern of the tested trait.

After many decades when its cultivation was prohibited, hemp is regaining its position as one of the most versatile cultivated crops. Multiplication of monoecious hemp varieties requires manual male plants rouging to keep a high share of monoecious plants in the population. It forces relatively small multiplication fields usually oscillating around 5 ha, where the use of big harvesting machines is not economically feasible. The B-800 mower prototype for hemp panicles proved to be a good alternative to harvest seeds of tall fibrous hemp. The test results of the mower analyzed in this study show that although seed loss on a moderate slope (0.37%) was significantly higher than on a flat slope (0.13%), it was still much lower than in the case of harvesting hemp seed with a combined harvester. Moreover, the field efficiency of 93% is very satisfactory as it is reported for much bigger machines. Finally, the harvesting costs proved to be much lower than most of the machines used for harvesting hemp seed.