DAILY SCIENCE

Crops are ‘imprinted’ by past droughts—which could help them prepare for future ones
Poring over 20 years of crop yield data researchers discover an intriguing form of natural drought resilience that offers clues for climate adaptation and food security.
November 19, 2021

Crops that have been exposed to drought seem to ‘remember’ those stressful occasions and be better equipped to deal with them next time they roll around, according to new research. This inbuilt resilience reduces yield loss, and may be a clue to achieving greater food security under the vagaries of climate change. 

The new discovery from the journal Food and Energy Security relies on two decades of climate and yield data gathered for two of America’s major crops, soybeans and maize. It draws on discoveries made in greenhouse experiments that have shown that crops seem to develop a degree of resilience to dryness once they’ve experienced drought. 

But, this study is among the first to show this phenomenon unfolding in the real world, on vast swathes of farmland in the American midwest—giving important insights into how crops might adapt to drought at landscape scales. 

By combining geospatial, field yield data, and remote sensing data, the researchers on the study tracked yield changes during key life stages of soy and maize crops on farmland in Illinois, Indiana, and Iowa. Then, they examined how these yields shifted relative to changes in precipitation and temperature over the 20-year stretch. 

When they pored over this detailed dataset, they picked up on some intriguing trends. Most notably, they found that crops that experienced drought stress during the early stages of their growth, were then typically able to produce more yields when drought hit again later on in their life cycles. “What we have seen is if the crop survives an early drought, because of that experience they perform better when a drought occurs very close to harvest,” the researchers explain

They call this a ‘priming’ effect: it’s as if the first drought inoculates crops against the worst effects of the second—and the benefits are quite significant. In fact, the soy and maize crops equipped with this natural resilience to late-season drought were able to reduce their typical yield losses by up to seven percent, compared to crops that didn’t receive the ‘priming’ benefit of early season dryness.

The study didn’t go into detail on exactly why dry conditions have this beneficial effect on crops later on. But previous laboratory research detailed in other papers has suggested that when exposed to dry conditions, plants adapt by investing more growth resources in their root systems, so that they can reach water sources deeper in the ground. That could set them up for greater success next time a drought sweeps through the region, the researchers explain.

Paired with these granular insights, the current study’s landscape-scale findings could help us predict how crops will fare under rising climate change threats—information that’s critical for maintaining food security.

Here, the researchers made a somewhat ironic observation about the midwestern context where they focused their study. While hotter, drier summers will still prevail in this region under climate change, projections show that early-season drought will be replaced by warmer, wetter springtimes. In other words, intensifying climate changes in coming decades will deprive crops of the early season dry weather prompt that has so far helped them adapt to summer droughts. 

On the bright side, having this landscape-level insight, now, into the climate-responses of two staple American crops could help us prepare new interventions that will help them weather these coming changes and protect their yields. 

As well as that, the findings may also be useful in other regions where drought remains a prevailing threat. By illustrating the real-world benefits of drought resilience in crops, the study furthers the case for interrogating the genetics that underpin these traits, an increasingly urgent focus in agricultural research. By identifying and amping up those traits in plants, we could get closer to future crops that can cope with the intensifying pressures of heat and drought.

In fact, spurred on by their recent findings, that’s what the researchers are planning to work on next. “Evidence that crops can use an early drought to ‘prepare’ for a later drought suggests that opportunities might exist to achieve a similar outcome through breeding,” they explain. 

Fu et. al. “Drought imprints on crops can reduce yield loss: Nature’s insights for food security.” Food and Energy Security. 2021.

Image: Pixabay

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