We’re all intimately familiar with the effects of heatwaves and droughts on crops, but plant researchers are taking a deeper dive at exploring how warmer nighttime temperatures are impacting crops around the world like corn, wheat, barley, and rice. From data that is circulating, the night minimum temperature of the contiguous U.S. has increased by +2.6 degrees Fahrenheit over the 1901 to 2000 state-wide night temperature mean. Here’s where it gets a bit crazy, recent research conducted by the International Rice Institute in the Philippines showed that every +1.8 degrees F increase in nighttime temperature could reduce rice yields by -10%, and wheat and barley yields by up to -41% and -29% respectively.
Researchers have confirmed that high nighttime temperatures have a stronger impact on grain yield compared to high day temperatures, but unfortunately, research on higher nighttime temperatures is not as advanced as its daytime counterpart.
Researchers are learning that our crops are incredible when you take a closer look at their processes and genetic building blocks. They are able to strategically allocate the resources they collect through biochemical calculations, meaning each evening plants take stock of the carbon they made during the day’s photosynthesis and then decide how much should be used for respiration during the night and how much should be allotted to developing seed, or the grains we eat. Higher nighttime temperatures increase plant respiration rates, potentially reducing the amount of carbon available for filling out the grains. But like humans, a plant’s system is geared around a certain temperature range, and with the higiher changes we are seeing, the plants are going to have to do a bit of restructuring to avoid some type of yield drag.
We are learning that grain “quality” is also being affected, according to Krishna Jagadish, a professor in the agronomy department at Kansas State University, whose team has set up sensor-filled tents at the University in order to study the impact on crops at a large scale. I’ve read the team noticed a change in the entire composition of grains in terms of starch, protein, and lipids when plants are exposed to higher night temperatures than are typical leading them to the hypothesis after working in rice, wheat, and corn, that the high-starch cereals will be more susceptible to high nighttime temperatures. Jagadish says the team is expecting that the yield and quality reduction in corn will actually be higher than rice and wheat.
Scientists understand that warm nights are bad for plants, there just not sure about all of the reasons why. In the mix, they are taking a closer look at how the changes are affecting the plant’s circadian clocks, which regulate various biochemical and developmental networks. Previously published research on the topic found that warmer nights can quickly throw off the plants’ schedules and rhythms by causing the untimely expression of various genes that plants use to set their circadian clocks. If further research bears out that this is why they do worse we could soon see plants bred with more robust versions of these genes. Lots of moving parts and things to think about as we head into the future. Wow! (Source: CivilEats, NOAA)
