Hafen, L. and E. C. Stevenson.
The sl and other stamenless tomato mutants are well suited to the production of hybrid tomato seed by hand pollination because emasculation is unnecessary and the stigma is fully exposed. However, several plant breeders have reported that they have discarded their program of incorporating the stamenless condition into the female parent of a good hibrid combination because the fruit quality of the F1 was inferior to that produced when the fertile variety was the female parent.
The expression of the stamenless character in the mutants is extremely variable. The environment, genetic constitution of a given plant, and the interactions between the two factors affect greatly the final expression of the male-sterility gene in the hybrid plants.
Through a backcross breeding program, we now have several male-sterile sl Ohio WR3 Globe lines. Between lines and within individual plants in the different lines, there is a difference in the quality of the fruit of the F1 hybrids. Certain lines produce fruit on hybrid plants that is rough and irregular; other lines produce some fruit on individual plants that is inferior in quality while the rest of the fruit on these plants is good. Also there are instances where all plants in a given line and individual plants within lines produce F1 fruits that appear as good as that found on F1 plants when fertile Ohio WR3 Globe is used as the female. When such plants or lines are found, it is suggested that they be multiplied asexually by rooting stem cuttings in sand. By this means large numbers of plants can be obtained which can be used as females in the production of hybrid seed. This method offers the possibility of using the stamenless strain in the production of F1 hybrid tomatoes that are as good in fruit quality as those produced when the fertile variety is used as the female parent.