The History of Corn

By Melanie Mathieson
Gardening Guru

The cultivation of corn (maize) began over 8,000 years ago in Mesoamerica, a geographical area which includes central and southern Mexico, and Central America. Corn was first domesticated from teosinte (Zea mexicana), an annual grass that mostly has value as a fodder plant, as it provides very little edible seeds.
Researchers believe that humans first domesticated corn by selecting the teosinte plants that had the largest amount of edible seeds until they eventually provided a substantial food source. This method probably took several generations to produce the corn we see today. In the process of developing corn, humans have transformed corn into a plant that can no longer self-sow. Modern corn requires someone to break the hard, tightly bound cob and plant the seeds. Wild teosinte, however, is very fragile and the seeds easily fall off and grow new plants. Interestingly, without human interaction, modern corn would probably cease to exist.
Growing corn can present a challenge for the home vegetable gardener, as it demands attention and it doesn’t provide a lot of return for the space it occupies. Though corn requires plenty of space in the vegetable garden, it is hard to beat its taste and tenderness, especially when freshly picked. Corn can be grown in any region, but the time it will take to mature, depends on the amount of heat it gets during the growing season. The key to high quality sweet corn is rapid growth, adequate soil moisture and nutrients, and harvesting the ears at optimum maturity.
Home gardeners who want to grow corn may choose from several different varieties including popcorn, dent, flint, corn, and sweet corn. Sweet corn is the most popular for the home gardener as improved hybrid cultivars are much easier to grow. They yield well, taste sweeter and store longer than older traditional cultivars. Sweet corn is best adapted to larger gardens since only one or two ears are produced per plant and several rows are recommended to ensure adequate pollination. However, even small plantings can be successful if planted in blocks rather than rows.
Corn is monoecious (mon-ee-shuss) which means that there are both male and female flowers on each corn plant. In some monoecious plants, male and female parts are in the same flower. In corn, male and female flowers are in different locations. The male flowers form a tassel which is at the top of the plant and the female flower is located at the junction of leaves and stem. It consists of a collection of hairs (silks) enclosed in the husks of what will become the ears. These silks are pollen-receiving tubes. Wind-blown pollen from the male flowers (tassel) falls on the silks below. Each silk leads to a kernel, and pollen must land on all silks for the ear to fill out completely with kernels. Kernel “skips” (ears only partly filled out with kernels) often are the result of poor pollination. This is why the silk can be hard to remove effectively because each one is attached to one kernel.
Sweet corn is a genetic mutation of field corn, producing kernels consisting mostly of sugar rather than starch. However, sugar in the kernels rapidly converts to starch after its prime harvest stage. Recent sweet corn hybrids have been bred for even higher sugar concentrations and slower conversion of sugar to starch. Several different types of mutations and gene combinations can result in sweet corn. Sweet corn is available as yellow, white, or bicoloured ear types. Cultivars vary in their days to maturity; they are classified as early, mid-, and late season. Late season cultivars generally are the best quality, but you want to look for cultivars that are early to mid season to ensure crop success in our zone. Read the labels carefully as many of the new cultivars are higher in sugar content and retain their sweetness longer so you can pick a variety most suited to your preference.
On a corn seed packet, you may find a short genetic abbreviation which describes the type of sweet corn; different types require different cultural conditions:
•“Normal” sweet corn (su) - Kernels contain moderate but varying levels of sugar, depending on variety. Sugars convert to starches rapidly after harvest.
•“Sugar-enhanced” (se, se+, or EH) - Genes in this type modify the su gene, resulting in increased tenderness and sweetness. Additionally, conversion of sugar to starch is slowed.
•“Super-sweet” or “Xtra-sweet” (sh2) - This gene, (sh short for shrunken), creates greatly increased sweetness and slow conversion of starch. The dry kernels (seeds) of this type are smaller and shriveled.
You can use this information when you are choosing the type of seeds that you want to plant and pick a variety that best suits your growing conditions and your taste preference. Now that you have some useful knowledge to help pick the right variety of corn, the next column will focus on some planting and growing tips.