Some Special Features of Sweet corn

In standard sweet corn cultivars kernel sugar content peak levels last in the field only for 2 days at 27°C or 5 days at 16°C before sugar is converted to starch. Even if ears are picked at peak sugar content, quality decreases rapidly after picking because of loss of sugar. In 24 hours after picking, sugar content declines to 8 percent at 0°C and up to 52 percent at 30°C. Thus, it is difficult to pick sweet corn before it turns starchy and supply it to the consumer before sugar levels decline. For these reasons, 'supersweet' cultivars are now preferred for commercial sweet corn production. These cultivars taste sweeter and convert sugars to starch more slowly on the plant and lose sugar at slower rate after harvest. While any lines with more sweetness than the standard are sometimes referred to as supersweets, technically only those lines with the sh2 gene should be called 'supersweets'. The name 'shrunken 2' reflects the fact that so little starch is present in the kernel that it appears shrunken, even when compared to standard sweet corn lines with the su-1 gene. Peak sugar levels of sh-2 hybrids range from 22-40%, compared to 5-11% in standard sweet corn. It is reasonable to expect commercial sweet corn crops in the future to be dominated by sh-2 hybrids, some people say the sh-2 hybrids are too sweet and lack the characteristic sweet corn flavour and tender kernels. However, kernels of many of the newer supersweet releases are as tender as those of standard cultivars. The original supersweets were also harder to grow and even the newest sh-2 hybrids challenge the grower because of isolation requirements from other types of corn.

Sweet corn cultivars with the se gene offer a third option for roadside marketers or those who will use or sell the corn within 1-2 days of harvest. These sugar-enhanced types start out with higher sugar content than standard sweet corns, but convert sugar to starch at the same rapid rate after harvest. Cultivars which are homozygous for the se gene have peak sugar contents of 12-20% while those heterozygous for the se gene have sugar levels of only 7-15 percent. The advantages of these cultivars are that they have the same tender kernels and creamy texture (sometimes described as 'real corn flavour'), as standard sweet corn, but seedling emergence characteristics are better and isolation requirements less stringent than for the sh-2 hybrids. If planted next to standard sweet corns, individual kernels may be like those of the standard sweet corn, but this is much less objectionable than when starchy, hard kernels develop on the ear, as is the case when standard sweet corn pollinates sh2 corn cultivars.