Firstly in Ukraine as the result of resiprocal interbreedings of autotetraploid (2n=4x=32) / diploid (2n=2x=16) and diploid (2n=2x=16) / autotetraploid (2n=4x=32) four sintetic triploid (2n=3x=24) hybrid forms (611-91, 13-93, 14-93, 18-93) have been obtained. Spontaneous triploid nectarinum 166-80 has been shared out from diploid hybrid seedlings population. Tetraploid and triploid nectarinum forms are valuable sources for directoinal selection and making hybrids with the complex of new signs, which are difficult or impossible to receive on diploid level.

Firstly in Ukraine as the result of resiprocal interbreedings of autotetraploid (2n=4x=32) / diploid (2n=2x=16) and diploid (2n=2x=16) / autotetraploid (2n=4x=32) four sintetic triploid (2n=3x=24) hybrid forms (611-91, 13-93, 14-93, 18-93) have been obtained. Spontaneous triploid nectarinum 166-80 has been shared out from diploid hybrid seedlings population. Tetraploid and triploid nectarinum forms are valuable sources for directoinal selection and making hybrids with the complex of new signs, which are difficult or impossible to receive on diploid level.

Purpose. Determination of peculiarities of anatomical and morphological characters of stevia plants to accelerate the identification of tetraploid forms. Methods. Field, laboratory and analysis-of-variance methods. Results. It was established that larger leaf area index (19–38%), fewer stomata per unit area (by 39–48%), larger diameter of pollen grains (by 42–92%) is a characteristic feature of anatomical and morphological characters of stevia tetraploid forms as compared to diploid ones. Conclusions. The parameters of leaf plate, the size of stomata and diameter of pollen grains are auxiliary selection criteria (rapid test). For tetraploid forms of stevia, leaf area index (the ratio of leaf blade length to width), size of stomata and diameter of pollen grains is truly larger as compared to diploid forms. Chromosomes number determination based on cytological analysis is the major and the most accurate criterion for selection of tetraploid forms, that seems advisable to use it at later stages of selection.

Purpose. Determination of peculiarities of anatomical and morphological characters of stevia plants to accelerate the identification of tetraploid forms. Methods. Field, laboratory and analysis-of-variance methods. Results. It was established that larger leaf area index (19–38%), fewer stomata per unit area (by 39–48%), larger diameter of pollen grains (by 42–92%) is a characteristic feature of anatomical and morphological characters of stevia tetraploid forms as compared to diploid ones. Conclusions. The parameters of leaf plate, the size of stomata and diameter of pollen grains are auxiliary selection criteria (rapid test). For tetraploid forms of stevia, leaf area index (the ratio of leaf blade length to width), size of stomata and diameter of pollen grains is truly larger as compared to diploid forms. Chromosomes number determination based on cytological analysis is the major and the most accurate criterion for selection of tetraploid forms, that seems advisable to use it at later stages of selection.

The article highlights results of research over simulative apomixes in pear and its utilization for obtaining haploids and homozygote diploids. It has been established that over 50% pear varieties with failed remote hybridization are capable of generating seeds of apomictic origin producing diploid plants. Genotypes displaying maximal inclination to apomixes have been singled out. Apomictic pear seedlings obtained from foreign pollination within the limits of the same combination are inherent in profound morphological diversity. Fruit-bearing apomicts originated from one and the same maternal plant differ to the same extent as hybrid seedlings of the same family. Genetic markers have enabled to establish that these are embryo sacs in which meiosis has completed that give rise to apomictic seeds. In vitro method as used for the purpose of increasing apomictic plants output has been illustrated. The greatest induction of apomictic shoots in vitro has been reached by alternation of BAP cytokinin at concentration of 1mg/l and 2 mg/l on the background of GA3 amounting to 1,5 mg/l. Grafting with shoots in vitro on non-sterile rootstocks of pear (Pyrus communis) has increased the output of plants up to 80%. A cytological assessment of 9 apomictic samples is provided. The cytological analysis of samples of apomictic forms has certified the presence of simulative haploid parthenogenesis in pear.

The article highlights results of research over simulative apomixes in pear and its utilization for obtaining haploids and homozygote diploids. It has been established that over 50% pear varieties with failed remote hybridization are capable of generating seeds of apomictic origin producing diploid plants. Genotypes displaying maximal inclination to apomixes have been singled out. Apomictic pear seedlings obtained from foreign pollination within the limits of the same combination are inherent in profound morphological diversity. Fruit-bearing apomicts originated from one and the same maternal plant differ to the same extent as hybrid seedlings of the same family. Genetic markers have enabled to establish that these are embryo sacs in which meiosis has completed that give rise to apomictic seeds. In vitro method as used for the purpose of increasing apomictic plants output has been illustrated. The greatest induction of apomictic shoots in vitro has been reached by alternation of BAP cytokinin at concentration of 1mg/l and 2 mg/l on the background of GA3 amounting to 1,5 mg/l. Grafting with shoots in vitro on non-sterile rootstocks of pear (Pyrus communis) has increased the output of plants up to 80%. A cytological assessment of 9 apomictic samples is provided. The cytological analysis of samples of apomictic forms has certified the presence of simulative haploid parthenogenesis in pear.