Wpływ wybranych form rodzicielskich na zawiązywanie owoców i nasion w hybrydyzacji oddalonej trzech gatunków drzew owocowych z rodzaju Prunus (śliwa japońska, morela, ałycza)

The aim of the study was to evaluate the efficiency of distant hybridization of selected fruit tree varieties in three  species of the genus Prunus – Japanese plum (P. salicina Lindl.), apricot (P. armeniaca L.) and myrobalan plum  P. cerasifera Ehrh.). The hybridization programme was carried out in a high plastic tunnel in the Pomological Orchard of the Research Institute of Horticulture in Skierniewice, in the spring of 2019. Eight parental genotypes, i.e. apricot – 4 genotypes (‘Early Orange’, ‘Harcot’, ‘Sirena’, ‘Somo’), Japanese plum – 3 genotypes (‘Czarnuszka’, ‘Trumlar’, D 17‒73) and myrobalan plum – 1 genotype (‘Amelia’) were used for the study. The hybridization programme was carried out while following the system of Japanese plum × apricot – 12 cross combinations, Japanese plum × myrobalan plum – 3 cross combinations. The obtained results showed that the influence of the Japanese plum genotype as a maternal form was greater than that of apricot as a paternal form on fruit-setting in the distant hybridization of these species. Furthermore, Japanese plum ‘Czarnuszka’ set fruit much better than ‘Trumlar’ after pollination with pollen of the same paternal forms of apricot. The ripe fruit also contained both properly developed seeds (viable), as well as those that had a wrinkled seed coat and malformed embryos (non-viable). The proportion of fruits with underdeveloped seeds varied and depended on the crossed species and on the genotype of the maternal form. In the crossing of Japanese plum × myrobalan plum, less underdeveloped seeds were obtained in relation to the total number of seeds (stones) obtained than in the crossing of Japanese plum × apricot. Embryo mortality and abnormal seed formation indicate the existence of post-zygotic barriers to crossability in the crossing of Japanese plum, apricot and myrobalan plum.