Food & Climate
Wheat is a strategic winter crop usually planted in November and harvested in April, grows best in temperatures below 30°C. But many countries have been experiencing higher temperatures towards the end of the growing season causes what is called heat stress, which manifests as wilting and results in lower yields.
For example, in 2022,India saw the hottest March since observed record-keeping started in 1901, with temperatures exceeding the normal by 4-6°C in many parts, according a report seen by “Food & Climate”.
In the plains of the north, the heatwave adversely affected human as well as plant life–in the latter instance, the standing wheat crop. Parvinder Singh, a seed farmer in Rambha, a village in Haryana’s Karnal, told “IndiaSpend” that farmers in his village lost 20-40% of the average wheat yield of 25 quintal per acre.
High temperatures not only affect plants directly but also increase evaporation rates, thus aggravating drought-like conditions and reducing agricultural and potable water supplies at a time when water is needed more than usual, said Global Research Programme Director – Resilient Farm and Food Systems, ICRISAT, Mangi Lal Jat.
He added: “Extra irrigation is vital to increase soil moisture and mitigate the heat stress on crops”.
India’s 2022 heatwave curtailed the country’s wheat production to 107 million tonnes, below the government’s initial forecast of 111 million tonnes. This triggered an inflationary trend and a ban on wheat exports.
Wheat is the government’s primary choice of cereal for free supply of rations to 810 million people across the country. Producing and storing sufficient wheat is vital for the country’s food security. But climate vagaries in recent years cut wheat stocks to 75.02 million tonnes by April 2024, the lowest level since 2008.
With India’s population expected to touch 1.5 billion by 2030, the projected demand for wheat for that population would increase to about 140 million tonnes. There is no visible path for domestic wheat production to increase to the optimal level when climate vagaries have kept the output fluctuating and more or less stagnant over the last five years.
To protect a staple of millions, in laboratories across India and experimental farms such as Singh’s, efforts are underway to develop and test drought- and heat-resilient varieties of wheat, a daunting task in the face of an ever-evolving climate.
“Prepare for one problem and the next season you face a new challenge,” a principal wheat breeder at Punjab Agricultural University (PAU), Achla Sharma said.
While researchers in Australia will focus on the development of heat tolerant wheat genetics in the next three years, according to “future farming”.
They will also zero in on what makes a wheat crop able to survive, grow and produce yields under high-temperature conditions.
The Grains Research & Development Corporation (GRDC) has partnered with the Australian National University (ANU) and industry partners to invest AUS $ 1.9 million in a three year research project to accelerate the development of climate-resilient crops.
According to Director of the Agrifood Innovation Institute (AFII) at ANU, Professor Owen Atkin, rising global temperatures are already having an impact on crop yields in critical food-producing regions in both Australia and overseas.
“In recent years we have seen an increase in heat waves induced by global warming, which have impacted wheat production across Australia and the world”, Professor Atkin said.
“Every one-degree increase in global mean temperature is predicted to result in a 6% to 10% decrease in wheat yields. This is extremely concerning given the pressing need to increase Australia’s crop productivity in line with a growing global population.”
However other studies have indicated that global wheat yield loss with the increase of each degree-Celsius temperature is 6.0 ± 2.9%, according to “frontier”.
They added that the high seasonal climate in January and February affects the formation of the double ridge stage.
The high temperature at the grain filling period is called terminal heat stress and the elevated temperature at sowing is called early heat stress.
Wheat development as well as growth are facing a difficult constraint brought on by early and terminal heat shocks.
Temperature increases also have been shown to hasten spike development while decreasing the number of spikelets and seeds formed per spike