On the low quality of certain sugary hybrids segregating shrunken-2

The new sugary hybrids that are segregating shrunken-2 are based on the development of viable sugary-shrunken inbreds that are used as one of the parents (usually the male). In selecting for increased germination approaching 100% in sugary-shrunken lines, we have found that selection is for a thicker tougher pericarp and a low wet percent of sucrose. The latter was measured with a hand refractometer on kernel juice pressed out in the milk stage. In all of the sugary-shrunken inbreds tested, the wet percent sucrose was only 15 percent which is at the low end of the scale for variation between standard sweet corn inbreds which range from 15 to 25 percent sucrose in their kernel juice. The low percent of starch in the sugary-shrunken combination gives it considerable taste preference despite its comparatively low wet percentage of sucrose.

But, what happens when we hybridize such sugary-shrunken inbreds with sugary inbreds of average quality? We obtain hybrid ears that carry 75% low quality kernels with 25% high quality sugary-shrunken kernels. The trade-off of so much bad for so little good leaves the balance in the red.

Walton C. Galinat and William F. Tracy

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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