Intra-population variability of oil content and fatty acid composition in modern hemp cultivars

Abstract

Purpose and objectives. To identify new promising material with high seed productivity, oil content and optimal fatty acid composition
 Results and discussion. It was found that the variability ranges of the oil content and seed weight increased under the influence of selections. Use of distant genotypes in hybridization contributed to the generation of high-oil lines, which later become donors of this trait. High oil content was recorded in hybrids derived from crossing cultivars and self-pollinated lines of the Central European eco-geographical type with cultivars and self-pollinated lines of the southern type. In this case, cultivar-line and line-cultivar hybrids (oil content of 36−39%), rather than inter-line ones, turned out to be the most successful results.
 Family-group selection is a basis for increasing and further stabilizing the oil content in seeds. The oil content was revealed to gradually increase during the breeding for increased oil content. It was found that the population variability of the seed oil content was from 33.99% to 46.98%.
 Continuous breeding selection gradually widens the expression range of the “oil content” trait from medium to maximum. In order to increase the practical value of cultivars via breeding techniques the seed productivity was also increased. The cultivars of different genetic origins, Hlesiia and Mykolaiychyk, as well as the cultivars of hybrid origin, Artemida and Harmoniia, were considered the most promising ones. In Mykolaichyk populations, the oil content gradually increased and stabilized at a level of 33, 35, or 37.8% without changes in the fatty acid composition of oil.
 The selections stabilized the oil content in cultivar populations. This proves the high efficiency of the developed breeding methods to create cultivars with high seed productivity and of targeted selection to increase the oil content in hemp seeds. Thus, the importance of a cultivar combining high seed yield and high oil output rises. The modern cultivars were ranked in order of decreasing oil levels in seeds as follows: Mykolaichyk, Artemida, Harmoniia, Hlesiia.
 Oil of all cultivars had an optimal ratio of omega-3 to omega 6 fatty acids of 1:3.1−1:3.9 (2016−2017). In 2018−2019, the ratio of omega-6 to omega-3 fatty acids was 4.0:1− 4.8:1. The linoleic acid content ranged from 55% to 58% and the linolenic acid content – from 12.58% to 18.23%. Mykolaichyk and Artemida were noticeable for gamma-linolenic acid. These results allow us to assert that the fatty acid composition of hemp seeds is unique and immutable during the breeding for increased oil content.
 Conclusions. We believe that the Central European type is a source and donor of high oil content, while the southern type – of a longer seed formation and, accordingly, of high oil accumulation.
 The heterosis phenomenon resulted from combining distant genotypes in one organism was observed. In this case, cultivar-line and line-cultivar hybrids, but not inter-line hybrids, turned out to be the most successful ones (oil content of 36−39%).
 The new hemp cultivars, Mykolaichyk, Artemida and Harmoniia, which combine high seed productivity with high seed oil content and unique fatty acid composition, have been created.