Inheritance of self-fertility in tetraploid red clover

Tetraploid red clover (Trifolium pratense L.) is highly productive and persistent, but often displays unsatisfactory seed yield. Previous research in tetraploid red clover suggested a possible association between self-fertility and seed yield. In this paper, we investigated the inheritance of the self-fertility trait in tetraploid red clover. Self-compatible (SC) and self-incompatible (SI) genotypes were available from previous studies. Four inbred populations (S1) were obtained through self-fertilization of SC genotypes. Eleven F1 populations were obtained from crosses between SI and SC genotypes. Self-fertilization of SC genotypes yielded significantly more seeds than SI x SC crosses (5228 vs. 1125 seeds/plant respectively). Subsequently, S1 and F1 progeny populations were evaluated for their ability to self-fertilize. S1 populations displayed 95% self-fertile plants, while F1 populations displayed 69% self-fertile plants. In addition, S1 populations yielded more seeds than F1 populations when self-pollinated (401 vs. 149 seeds/plant respectively). These results clearly show that the ability to self-fertilize is a heritable trait in tetraploid red clover. To get more insights in the inheritance of self-compatibility, a subset of S2 and F2 populations has been selected for a next round of self-fertilization to be performed during summer 2021.