Hayes and Garber - Cucurbit Breeding

40 BREEDING CROP PLANTS
between the partly closed glumes until the bases protrude.
They then tip over and dehisce, spilling part of the pollen outside
the flower. Being lower than the stigma the pollen can not reach
the stigma of the same flower. There is some evidence (Ulrich,
1902) (Fruwirth, 1909) which indicates that the rye flower is
self-sterile, but that the spikelet is not necessarily so. Further
studies are needed to clear up this point.
Ulrich (1902) found significant differences between varieties
and individuals of the same variety in the amount of self -sterility.
The following table shows some of his results, obtained from
artificial and natural pollination. Artificial pollination was
obtained by covering the head with double paper bags.
TABLE II. SELF-STERILITY IN RYE
Artificial pollination