Evidence that red clover plants of the Dollard variety differ in production of fertile ovaries is presented. The amount of ovary sterility arising through failure of the embryo sac to complete its development is apparently controlled by genetic factors and influenced by environmental conditions. Consideration of the data on frequencies of ovary fertility of plants in nursery lines and in progenies of crosses, together with data on their seed production, leads to the conclusion that ovary sterility is an important limiting factor on the ability of a plant to produce seed. Even under adverse environmental conditions; appreciable ovary sterility is still the primary limiting factor in restricting seed production and hence, among plants affected by ovary sterility, it is not surprising that we found significant correlation between the percentages of ovary fertility and seed yields.
