PlantwisePlus Blog

Wheat: Getting old before its time. Source: Markusram, Flickr

Many of us dislike getting older, but you can usually predict how it will go: next year you expect to be 1 year older and you expect your body to be 1 year older. But what if instead of continually growing over a year, your body instead decided to grow for 6 months and then stop altogether until next year? Well, I’m sure that we’d all be rejoicing in the streets.

However, farmers are soon to be facing this very possibility and are starting to worry about it. But, it’s not their own bodies that they’re worried about, instead it’s that of their wheat yields. They’re predicted to stop growing earlier, because they’re actually ageing too quickly…

The new study, led by Stanford University, examined the effects of increases in global temperature on wheat yields over nine years in northern India. It found that climate change-induced temperature rises will lead to lower crop yields for farmers.

The study discovered that these higher temperatures caused wheat crops to age faster which resulted in their growth stopping earlier, producing smaller yields. It has been predicted that this increased ageing (also known as senescence) will result in wheat yield losses of up to 20%.

Normally 1-2 weeks after pollination the grain kernel (edible part) begins to accumulate starch and protein rapidly and increases in size. It is during this crucial growth period that the plant fills the ‘grain head’ before being harvested. At a certain age this part of the plant stops being filled because it is assumed that it has reached its maximum size.

However, the faster rate of senescence means that it’s reaching this age quicker and stops filling its grain head a lot sooner than it should. The plant has less time to fill its grain head and therefore it grows smaller grain that provides lower yields for farmers.

These findings are especially significant when you consider that wheat is the second most produced crop in the world. So any decreases in wheat yield will represent a challenge to maintaining existing food security. An ever-increasing world population that needs to be fed makes this threat to wheat yields even more important.

Fortunately, there are ways to reduce wheat losses due to higher temperatures. In the short-term, heat-tolerant varieties of wheat are needed to endure the hotter weather. Farmers may also be able to change the timing of when they grow and harvest wheat crops in order to adapt to climate change.

In the long-term, a reduction in greenhouse gas (GHG) emissions and measures to mitigate climate change are desperately needed. Future temperatures are already predicted to increase slightly, due to past GHG emissions, but a reduction in our current GHG emissions could prevent even greater temperature rises. Whether there is the international willpower to mitigate climate change is unclear, but it ‘s becoming recognised that climate change will have negative effects on our food security. However, with no new wheat anti-ageing creams on the horizon, scientists and farmers will need to work together to identify and solve these new problems.

More information available from Reuters.