A new kind of sweet corn, Pennfresh ADX Hybrid, with naturally fine sweet corn flavor and the ability to stay fresh for several days, has been developed and introduced by Pennsylvania State University. The seed is expected to be available for purchase nationally in 1979. The corn was developed by Drs. Douglas Garwood and Roy Creech, Penn State plant breeders.

Sweet corn has long been a favorite garden vegetable, but it lost its quality rapidly after being picked. The sooner it was prepared, the better. It could be refrigerated (35 to 40 degrees F.) for two or three days with only a moderate reduction in eating quality.

The development of Pennfresh ADX began in 1966 when Agway Inc., Syracuse, N.Y., provided a grant-in-aid to Creech for the basic studies of starch synthesis in corn endosperm. Creech's research showed that the kernels of some corn retained very high sugar levels long after normal sweet corn harvest. Recognizing the potential for use in fresh market corn, Creech isolated the genes responsible for this superior quality.

The three recessive genes isolated, and later identified as amylose-extender (ae), dull (du) and waxy (wx), or ADX for short, were found to act independently to influence the conversion of sugars to starch in the corn endosperm. Garwood incorporated the three recessive genes into a horiticulturally acceptable variety. After numerous backcrosses and repeated selections, ADX was ready for its initial test.

"Pennfresh ADX has increased levels of sugar at the fresh market stage of development compared with conventional hybrids," says Fred W. Williams, Agway product manager, seed division. "However, the sugar levels are less than found in the super sweet hybrids. This overcomes the objectionably sweet character typical of this type of corn.

"Pennfresh ADX exhibits good post-harvest sugar retention (stays fresh longer). Four days after harvest, Pennfresh ADX was clearly superior to Illini-X-tra Sweet (super-sweet varieties) in sweetness, flavor, tenderness and texture.

"Germination and field vigor of Pennfresh ADX is rated equal to Iochief and superior to Illini-X-tra Sweet. This is due to the greater amount of endosperm storage capacity of ADX as compared to the shrunken-2 type corns (shrunken-2 is a genetic factor that conditions a high level of sugar in the kernels).

"In a recent field evaluation to ascertain consumer acceptance, Pennfresh ADX proved highly acceptable to an unusually large proportion of respondents in all quality traits. Of the 370 participants, better than 90 percent responded with a superior rating for sweetness, flavor, tenderness and texture."