Morphology and fertility of a spontaneous octoploid of white clover [Trifolium repens L.]

In the progeny of a hybrid obtained after crossing local Polish and local Bulgarian white clover genotypes one octoploid (2n=64) plant was selected. In view of difficulties to obtain seeds, the octoploid plant was vegetatively propagated. The progeny of the octoploid obtained as a result of self- and cross-pollination of cloned plants was examined and compared to related tetraploids with respect to morphological characters, fertility and embryo sac structure. Vegetative and generative organs of the octoploid were slightly larger than those of tetraploids. The number of flowers per head was larger in the octoploid than in tetraploid plants. The spontaneous octoploid appeared to have a low fertility after both cross- and self- pollination. It was most probably caused by low pollen viability, by decline of megasporocyte and megagametocyte in the process of ontogenesis and by a smaller ovule number per ovary. Seeds of octoploids were partially underdeveloped and only 23.85% of them gave rise to seedlings.