Effect of pollen competition and stigmatic receptivity on seed set in white clover (Trifolium repens L.)

The effect of competition between incompatible and compatible pollen grains on the seed production of white clover was studied. Stigmatic receptivity was also studied. A selection line of white clover that has red leaves was used as a pollen donor and as a genetic marker to allow determination of th e pollen donor responsible for ovule fertilisation. Results show that incom patible pollen did not inhibit compatible pollen grains from fertilising ov ules and producing seeds, although it did slightly impair seed yield. At te mperatures of 20/10 degrees C (day/night) stigmas of white clover remained receptive to additional pollination up to 32 h after an initial compatible pollination and 40 h after an incompatible pollination. The results imply t hat factors other than inadequate pollination and the self-incompatibility system are responsible for failure of white clover to attain its potential seed yield.