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The rise of extreme weather -

In recent years the effect of climate change on weather patterns is plain for all to see. From ice storms in Texas to bushfires in Australia, extreme weather is clearly on the rise.

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Tremendous impact -

Incidents of extreme weather can be very disruptive. They can bring whole communities to a standstill and even, tragically, claim people’s lives.

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Climate change and crops -

A lesser-known, although potentially devastating, repercussion of extreme weather, particularly extreme heat, is related to the harvest of certain crops.

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The problem with drought -

Of course, it is no great secret that extreme heat is bad for crops. Heat and drought have caused poor harvests since time immemorial.

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Alarming discovery -

However, researchers are now beginning to realize that extreme heat can damage crops in another, very alarming way: by killing pollen.

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Killing pollen -

It is becoming increasingly clear that extreme heat can damage pollen and prevent fertilization in crops such as corn, peanuts, and rice.

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Current approach -

In a bid to combat this, many farmers aim for their crops to bloom after the cold of the winter has passed, but before the heat of the summer arrives.

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Closing the gap -

However, as climate change increases the number of days that temperatures reach 90°F (32°C) across the globe, it is becoming almost impossible to get the timing right.

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The challenge -

Remembering that without effective pollination much of our diet is at stake, the race is on for researchers to find a way to help pollen beat the heat.

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To the root of the problem -

As Gloria Muday of North Carolina’s Wake Forest University explains, "The critical parameter is the maximum temperature during reproduction.”

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Pollen and fertilization -

We will not go into detail about plant reproduction here, but we will note that pollination (the transfer of pollen to a plant or flower) is key for fertilization.

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In a nutshell -

A single cell from a pollen grain grows into a tube that delivers genetic material to a plant’s ovary. High temperatures cause the proteins involved in this process to break down.

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Not all plants are made equal -

While the discovery that extreme heat is a pollen killer is alarming, it has become increasingly clear that not all plant cultivars (AKA plant varieties) are equally susceptible to heat.

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The approach - Researchers are therefore looking at the molecular mechanisms that allow the pollen from some crop cultivars to survive the heat, while others die off.

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Case study: tomatoes -

For example, the fertilization of tomatoes is known to be particularly heat sensitive. Currently, tomato growers time their crops to bloom during cooler periods.

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Closing the window -

However, according to tomato farmer Randall Patterson, "If it does get hotter, and if we do have more nights over 70°F, that's going to close our window."

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University-led research -

Gloria Muday, of Wake Forest University, is part of a cross-university team that is working to discover which molecular mechanisms and genes would help tomatoes to survive heat.

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Genetic modification - The idea is that if they can isolate those mechanisms and genes, they will be able to grow tomatoes that are more resilient in the face of extreme weather. 

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Crop growers -

At the same time, many crop breeders are themselves working hard to develop and grow crops that are better able to withstand heat.

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Crop breeders - One of those crop breeders is Rebecca McGee, a pulse crop breeder at the US Department of Agriculture's Agricultural Research Service in Pullman, Washington, who believes we must adjust the crops' ability to handle heat for specific locations and climates. 

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Verbatim -

To quote McGee, "If farmers in the Pacific Northwest or in the Mountain States or in the High Plains are going to grow peas, and the climate is going to be warmer, then we have to have peas with more heat tolerance.”

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Case study: pulses -

Pulse crops, including dried beans, peas, lentils, and chickpeas, do not need a lot of moisture. However, their pollen aborts if they get too hot, just like tomatoes.

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2021 heat weave -

In 2021 a heat wave in the north west United States wreaked havoc among pulse plants. Chickpea production, for example, fell by more than 60%.

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Another approach -

McGee is breeding some of her crops to be more resistant to heat, but she is also taking another approach: breeding crops to withstand cold.

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Autumn crops -

Generally pulse growers in the northern United States plant their crops in the spring. McGee is growing peas, lentils, and chickpeas that are sown in autumn instead.

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The concept -

The idea is that these will survive the winter and then have a head start on flowering early in the summer before a potential heat wave hits.

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Alternate solution -

For some farmers a simpler solution is to switch crops altogether, since there are crops that can withstand and even thrive in tropical climates.

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All in all -

Whatever the solution crop growers decide to go with, it is clear that climate change has an effect on harvests, and that effect is here to stay.

Sources: (BBC)

See also: Climate change: how extreme weather is affecting our world

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