Characteristics of artificial pollination of large-flowered species of Coelogyne Lindl. (Orchidaceae) under greenhouse conditions

The efficiency of xenogamous, geitonogamous and autogamous artificial pollination was studied in a number of orchids of the genus Coelogyne Lindl. under greenhouse conditions. Fruit and seed production was lower in geitonogamous and autogamous pollination than with xenogamous pollination, with geitonogamous pollination producing more fruit than autogamous pollination in several species. Regardless of the pollination method and the degree of pollen-stigma compatibility, all experimental species exhibited a phenotypic response of the flower to pollen exposure (post-pollination), manifested by stigma closure and gynostemium growth. Geitonogamous and autogamous pollination primarily exhibited gametophytic self-incompatibility, whereas xenogamous pollination, in addition to normal ovule and fruits development, also showed late-acting self-incompatibility. The anatomical and morphological manifestation of gametophytic self-incompatibility was the arrest of pollen tube growth in the stylar channel of the gynostemium. Two variants of late-acting self-incompatibility have been described: 1) death of embryo sacs and arrest of ovule development at the fertilisation stage (ovular incompatibility); 2) death of embryos with preservation of seed coats (early embryonic abortion). Partial ovule and embryo death due to late-acting self-incompatibility does not affect the normal development and maturation of the remaining ovules and fruits.