Selfish Wheat Won't Feed The World, But Unselfish Crops Might

Professor Jacob Weiner with some of the mixed varieties of wheat he tested to see how they grow cooperatively. University of Copenhagen

Scientific plant breeding has enabled food supplies to keep pace with a growing population in a way that was once thought impossible. However, according to a new study, we've been doing it wrong, focusing on the individual plant rather than the collective. 

Professor Jacob Weiner of Copenhagen University experimented with 35 varieties of spring wheat (Triticum aestivum). Most plant breeding involves finding the plants that grow best under particular conditions and breeding them intensively. More recently, it has focused on finding specific genes that maximize production. Weiner went in the opposite direction, growing some varieties alone in monocultures, and mixing others together in polycultures.

Reporting in Ecology, Weiner found the types of wheat that thrived in diverse environments were not necessarily the ones that did best as monocultures. The varieties that did best in a mixed environment did so at the expense of those around them, for example by producing extra roots to steal others' nutrients.

When planted in a monoculture, these selfish varieties had no one to sponge off and did roughly as badly as the polyculture's worst performers. The best-performing monoculture plants were middle-runners in a mixed group.

The varieties of wheat that did the best in mixed environments (right-hand side) did not give the biggest yield when planted together because they couldn't steal nutrients from others. Weiner et al. Ecology

"The crops can be compared to a sports team,” Weiner said in a statement. “If every player is rewarded for scoring the goals, the team will not score as many goals as it would, had the players cooperated. In the same way, we can't increase crop yields by selecting the most successful plant individuals for breeding."

Varieties chosen for their cooperative nature produced 35 percent more grain than those gaining high individual yields at the expense of their neighbors.

The success of any group of social animals always depends in part on members being able to place the interests of the collective over their own short-term benefit. Finding that it also applies to plants could revolutionize how crops are bred in future.

Weiner thinks breeding for cooperation has great potential. The traits we have looked for in crops, such as faster growth or more efficient nutrient use, are those that have already benefited plants in the wild so natural selection has taken them almost as far as it is possible to go.

When unselfish traits, like the height of dwarf wheat that stops it from blowing over, have been selected, it has usually been accidental. Weiner proposes actively looking for these characteristics.

"We can only do better than natural selection if we try to do something natural selection will not do, such as breed unselfish plants" Weiner said.

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