The Road to Better Corn is “Open”

by Jeffery Goss Jr. of Springfield, MO

Most farmers take it for granted that hybrid corn will yield more, acre for acre, than an open-pollinated variety. However, as advocates of OP corn have always been apt to point out, yield isn’t everything. OP corn is well known to be more nutritious than hybrid strains, having more minerals, free sugars, and protein (sometimes up to 5% more) and less plain starch. Even animals will almost always preferentially consume OP ear corn if given a choice between it and a hybrid. Moreover, the wider gene pool of OP corn makes it resistant and/or tolerant to a wider variety of microbial diseases and insect pests.

It may soon be, however, that “yield isn’t everything” could become a moot point. That is because a group of farmers participating in an intensive plant breeding project are endeavoring to select a series of OP dent corns that yield on par with comparable hybrids. The Seedtime Co-Operative, with members in Missouri, Tennessee, and Kentucky, is starting by identifying the highest-yielding OP dents already in existence, which will then be worked on for improved yield and standability.

One might readily wonder, if such a goal is even possible, why has no one done it already? The answer is that a few almost have, but not many, because there are very few plant breeders trying. Since the widespread adoption of hybrids in the U.S. during the 1940s, most major institutions have directed their maize programs almost wholly to the selection of improved hybrids. The discovery of hybridization and its instant yield increases may have initially made continued OP work seem pointless, and later the greater profitability of hybrids to the major seed companies made them the more lucrative business field, as opposed to new open-pollinated introductions which only need to be sold to each farm once, except in the case of a total crop failure.

Plant geneticists now have developed techniques that allow selection to take place more quickly, such as the crossing of superior inbred lines.

“Inbreeding concentrates the genes so that they can be identified,” explained Luke Eby, coordinator of the Seedtime Co-Operative. “If the genes produce poor traits they can be eliminated; if they produce superior traits they can be saved…if you select many superior lines from an open-pollinated variety and then recombine them, you will have a superior, improved open-pollinated variety.”

Plant physiologists have also discovered more details about genetic inheritance in plants than was known in the 1930s, when the last major effort was done on OP field corn breeding in the U.S. For example, they have discovered which traits are likely to be cytoplasmic (e.g., cold and/or heat resistance) and which are more likely to be the result of ordinary Mendelian, nuclear-genetic inheritance (e.g., plant height or disease resistance). This kind of knowledge can speed up the selection process when both the pollen parent and the seed parent are chosen selectively, as opposed to the mass selection method common in maize breeding work, in which only the seed parent is considered. Another genetic topic understood more fully today than seventy years ago is gene linkage, and which genes are linked to which others. In a crop that exhibits xenia, such as corn, knowledge of gene linkage can allow more thorough seed sorting and reduce the need for time-consuming grow-outs.

“Open-pollinated corn has a much broader resistance to stresses,” Eby observed. “In 1970 there was a nationwide epidemic of Southern Corn Leaf Blight. At that time 90% of the corn grown in the U.S. was susceptible. Open-pollinated varieties were little affected. We have an opportunity now to take steps that will assure that our children will be able to grow non-GMO corn.”

Eby thinks it may take 20 to 30 years to entirely replace hybrid corn with new improved OP varieties, considering the complexity of traits such as yield and nutrition, which are not controlled by single genes. Simple one-gene traits, however, are much quicker to select for, especially with modern genetic knowledge. One biochemist in Kansas, who was contacted in the process of researching this story, recalls an experiment with selection of corn for extraordinarily high oil content. By intensive methods, the researchers were able to quadruple the oil level in the corn. Oil content is a relatively simple trait, controlled by a few genes. Color is controlled by one or two loci (genes), and yield is controlled by dozens of genes on multiple chromosomes.

The first step, however, must first be accomplished before the Seedtime Co- Operative can begin intensive plant-breeding work. That first step is to assess the strains and varieties already most amenable to yield improvement, a large task and one that is requiring many grow-out plots this year and next. The majority of today’s OP corns yield about 70 bushels to the acre on good land, which – as Eby points out – is only slightly higher than the average yield a hundred years ago. Some strains are much-better yielding, however; ‘Neal’s Paymaster’ and ‘E-95’ are two examples of OP corn varieties that can yield up to 150 bushels on a good acre. The grow-outs being done by the cooperative are being studied with detailed notes, which Professor Dennis West of the University of Tennessee plans to mathematically analyze at the end of the 2011 corn season.

The next steps planned are top crosses and hand pollinations. The objective of these will be to create inbred lines of the highest-yielding varieties, increase the seed, and cross the best of these strains for an improved and re-diversified strain of the original variety. Such a process takes a total of about five years, although the last two years of this are mostly devoted to increasing the seed to commercial or large-field quantities, and removing undesirable genetic outliers for stability.

Additionally, one of Eby’s intermediate goals is to make the parent lines (P strains) available to farmers so they can produce their own hybrid seed, so those who still desire to grow hybrid corn can do so without depending on far away seed companies and distributors.

“I would like to supply the Hybrid seed to those farmers…(that) will not grow OP corn,” Eby announced in a letter to participants and other interested farmers. “If we can make the parent lines available to the farmer so he can grow and save his own hybrid seed, it will be a step in the right direction. If we are going to improve the OP corn to the point that hybrids no longer make sense, we need farmers who are committed to OP corn. I appreciate that sentiment and hope it grows.”