Seed reproduction of some introduced Onobrychis (Fabaceae) species in the semi-desert zone of Uzbekistan

The article discusses the reproduction processes of four introduced species of the genus Onobrychis Mill. in the semi-desert zones of Uzbekistan. On the foothill flatland, in annual species O. micrantha Schrenk and O. pulchella Schrenk. vegetative-to-reproductive transition occurs on the 28–30th day of vegetation, and in perennials O. chorassanica Bunge and O. seravchanica B. Fedtsch. – on the second year of vegetation. Flowering and fruiting occur acropetally along the shoot. The studied species are predominantly allogamous. In the semi-desert, the main pollinators of sainfoines are bees from the genera Andrena, Melitta, Anthophora and the honey bee (Apis mellifera). In annual species O. micrantha and O. pulchella the presence of autotripping is observed. The pollen fertility of the studied taxa was quite high (85.2–91.4%), and the fertility of ovules is from 72.3 (O. seravschanica) to 87.2% (O. pulchella). Fruit maturing is observed in late July – early August. From the beginning of vegetation to fruit ripening, it takes 65–73 days for annuals, 114–123 for O. chorassanica, and 126–131 for O. seravchanica. The potential seed productivity of plants is from 57.2–68.4 (O. micrantha) to 689.3–815.8 (O. chorassanica) ovules per shoot, and the real seed productivity is from 12.2–19.2 (O. micrantha) up to 131.8–152.3 (O. chorassanica) seeds per shoot. In introduced species of Onobrychis, the coefficient of the seed productivity, which is an indicator of plant adaptation to semi-desert conditions, ranges from 15.1 to 42.0%. Reduction of real seed productivity of plants is determined by the influence of a combination of abiogenic and biogenic factors.