For white pollen to be used as a male sterile system, or for enrichment screening, the consequences of mixed pollinations need to be known. It is also important to explore the basis for the functional incapacity of white pollen, including whether yellow pollen can serve as a "helper" for white. The following experiments were conducted with these interests in mind.
Mixtures were made of roughly equal quantities of white pollen with others, with results as follows:
The above kernels that possibly represent transmission of white pollen (PP1) are still to be progeny tested, but it is evident that white pollen is not aided much, if at all, by admixture with yellow pollen.
Parallel pollinations were made for each of the above 7 tests with PP2 samples collected and dried overnight in a tassel bag near the heat register in the greenhouse before mixing with fresh white pollen (PP1):
The possible PP1 kernels again are to be progeny tested, but the dried pollen did not aid white pollen much, if any. The number of PP2 pollen grains surviving in crosses 3, 5 and 7 is surprising but may be an artifact of handling variations for the drying.
Pollination on two successive days, the first with white pollen and the second with yellow, was used to determine whether white pollen interferes with the receptivity of silks or ovules, as follows:
Once again progeny tests are to be carried out on exceptions. The first cross indicates that the ratio of C2 to c2 is not affected by prior pollination (in this case 2 days earlier). White pollen on the others has not prevented subsequent fertilization by yellow pollen.
A further indication that white pollen does not affect the physiology of the silk is that the silks at the point of attachment to the ovule, when examined even 3 or 4 days after pollination with white pollen, do not show the collapse and pinching off that is characteristic of pollinated silks within a day after pollination with functional pollen.
E. H. Coe, Jr.
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