New Delhi: 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.
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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 vernalisation 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.
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Rice & wheat cultivation
In India, rice and wheat cultivation go hand-in-hand. So, another issue that arises with early wheat sowing is stubble burning after rice cultivation.
Indian farmers tend to harvest their paddy crop just before the wheat crop — between October and November. To ensure that the stubble from the crop is cleared out in time for the next harvest, a large number of farmers set the farm residue on fire — smoke from these farm fires is a major source of pollution across the Indo-Gangetic plains.
Sowing the wheat crop any earlier would put further pressure on the farmers to clear out their paddy fields early.
To get around this issue, IARI — along with the government — has decided to stop the production of the Pusa 44 variety of rice that has a longer maturity period of 150 days.
“Our focus in the rice breeding programme now for the whole of Punjab, Haryana and western UP is to develop varieties which are of a [shorter] duration range of 125-130 days,” Singh said.
This would ensure that the paddy crop completes its life cycle by the end of September or October leaving enough time to sow the new wheat crop.
“The farmers will definitely not like to go for long-duration [rice] varieties because 155 days’ duration varieties will take at least 5 to 6 more days of irrigation,” Singh said.
The institute has already developed a number of such [short-duration] rice varieties including the Pusa 1509, Pusa 1692 and Pusa 1847 — which take under 125 days to seed maturity.
The way ahead for HD 3385
The team has been working on developing the HD 3385 variety for six years, Singh said.
Singh added that the institute has registered HD 3385 with the Protection of Plant Varieties and Farmers’ Rights Authority (PPVFRA) — a statutory body that seeks to address the rights of plant breeders and farmers on an equal footing.
Meanwhile, Delhi-based DCM Shriram Ltd-owned Bioseed — a biotechnology company with expertise in crop science — will carry out trials.
If all goes as planned, Singh said he hopes that the HD 3385 variety will hit the market this year, in time for the 2024 harvest season.
(Edited by Anumeha Saxena)
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