How ICAR’s new wheat variety can beat India’s brutal heatwaves in face of climate crisis

By Mohana Basu

The scientists at the Indian Council of Agricultural Research’s Indian Institute of Rice Research (ICAR-IARI) have developed a new wheat variety that can withstand rising temperatures and produce a higher yield for farmers.

This is a significant development in the light of growing concerns about how the climate crisis-induced heat stress may affect India’s wheat crop. 

Wheat crop experiences high temperature stress during flowering stages, which is termed “terminal heat stress”. Terminal heat tolerance means that the crop is able to withstand the heat at the flowering stage.

The ICAR-IARI wheat variety, called HD 3385, has got high temperature stress tolerance, particularly towards the end of its crop cycle, and has been developed particularly for terminal heat tolerance. 

IARI director Ashok Kumar Singh told ThePrint Friday: “If you remember, last year, it was sometime around between 27 and 29 March that there was a wave of heat, and that had an effect on wheat production to a certain extent. That is why the government is very proactive this year to make sure that the crop does not shrivel up.” 

Last year, Delhi, Uttarakhand, Rajasthan, Punjab, Haryana and Jharkhand reeled under record heatwaves. And there’s unlikely to be any respite this year, warned the India Meteorological Department (IMD) earlier this month. 

The wheat production fell to 106.84 million tonnes in 2021-22 crop year (July-June) from 109.59 million tonnes in the previous year due to heatwaves, according to official data.

Prime Minister Narendra Modi chaired a high-level meeting Monday to review preparedness for “hot weather”. 

To protect wheat yields, early sowing without the danger of yield reduction is the key, and the new variety accommodates these needs, said Singh.

Cross-breeding of wheat varieties

Wheat is usually sown between 1 and 20 November. This means that the grain starts getting filled with a milky sap during the month of March. The crop is ready for harvest by the end of March. 

However, if at that time the crop faces high temperatures, the grain does not fill up properly. This leads to shrivelled grains — reducing the overall yield. 

If wheat varieties are sown earlier than November, they have a tendency to come to flowering early. This results in a poor accumulation of biomass — leading to early heading and lower yield. 

To overcome this, the team developed HD 3385 from crossbreeding of two varieties that had the desirable traits (parent varieties names not known), said Singh. The crop should be sown between mid-October and 25 October, which is about  15 days earlier than the regular sowing period, he explained. 

The HD 3385 variety has been developed to not only make the crop tolerant to heat stress, but also increase the yield. 

The new wheat variety takes 130 to 160 days to grow, as opposed to 80-95 days if sown in November, and has a yield potential of about 75 quintal per hectare, Singh added.

Notably, another heat-resistant variety of the crop, HI 1636 or ‘Pusa Bakula’ that the ICAR released last year, has a yield potential of 72 quintal per hectare.

The team has bred the crop to incorporate what is known as ‘weak virtualisation gene’, which allows for early sowing. 

“Because of this gene, even if these varieties are seeded early, they will not come to flowering unless the minimum threshold of temperature is reached,” Singh said. 

“And therefore, they get enough time for vegetative growth and to accumulate more biomass. It is the biomass that is converted into grain,” he added.

The team also had to introduce characteristics that allowed the wheat grain to have higher  temperature tolerance for germination, since soil temperatures during the month of October are a little high.

By sowing seeds 15 days early, the new variety can accumulate more biomass, and grain-filling occurs before the temperatures rise. 

This article has been republished from The Print