Research for improving natural selfing in sunflower cultivars (Helianthus annuus L.) II. - Some characters allowing the pollen to reach easily the stigma papillae

In three varieties, 38 hybrids and 39 lines, the hybrids tended overall to produce more pollen than the lines. Pollen production had highly significant heritability estimates, but did not show heterosis. The pollen of the hybrids had a higher overall in vitro germination rate than that of the lines. The degree of pollen agglutination varied amongst all the material studied; pollen spine length also varied. Three abnormal types of floral development are described. Of these, the most promising for breeding autogamous forms was a type in which the lobes of the stigma open before emerging from the anther tube.