ICAR develops wheat that can beat the heat

ICAR director-general Himanshu Pathak (left) at the IARI’s wheat trial field with principal scientist Rajbir Yadav (centre) and director A.K. Singh (right). (Express Photo by Harish Damodaran)

There are fears of a repeat this time, with both maximum and minimum temperatures already 3-5 degrees Celsius above normal in many wheat-growing areas. But whether or not March 2022 will happen again, climate change – specifically, the tendency for the early onset of summer with hardly any spring break – has definitely made India’s wheat crop vulnerable to terminal heat stress during the final grain formation and filling stages.

Is there a way out? One “beat-the-heat” solution put forth by scientists at the Indian Council of Agricultural Research (ICAR) is to advance the time of sowing.

Wheat is a typically a 140-145 days crop planted mostly in November – before the middle of the month in Punjab, Haryana, Rajasthan and Madhya Pradesh (post the harvesting of paddy, cotton and soyabean) and the second half and beyond in Uttar Pradesh and Bihar (after sugarcane and paddy). If sowing can be preponed and taken up from around October 20, the crop isn’t exposed to terminal heat, with much of the grain-filling being completed by around the third week of March. It can, then, be comfortably harvested by the month-end.

But the solution is easier said than done – for the simple reason that the wheat sown before early-November is also prone to premature flowering.

“The crop seeded in the first half of November normally takes 80-95 days to come to heading (i.e. for the ‘baali’, or earheads bearing the flowers and eventually grain, to fully emerge from the wheat tillers). But if you sow in October, heading is cut short by 10-20 days and occurs in 70-75 days. This affects yields, as the crop does not get enough time for vegetative growth (of roots, stems and leaves),” explained Rajbir Yadav, principal scientist and wheat breeder at the ICAR’s New Delhi-based Indian Agricultural Research Institute (IARI).

To get around the problem, IARI scientists have bred wheat varieties with what is termed “mild vernalisation requirement” or the need for a certain minimum period of low winter temperatures for initiation of flowering. In this case, the crop, when sown in October 20-25, will come to heading only in 100-110 days. Adding another 4-5 days for pollination, it leaves a long window from mid-February for grain formation and filling.

Maximum temperatures should ideally be in the early-thirty degrees range during the 30-40 days when the kernels are formed, take in nutrients from the stems and leaves, and ripen after hardening and drying. The early-sown IARI varieties not only have a longer window for grain development, but also for vegetative stage growth between germination and flowering. “By not heading early despite early sowing, the new varieties are able to accumulate more biomass along with grain weight,” Yadav pointed out. And they can beat the heat.

The IARI scientists have developed three varieties, all of them incorporating genes that are responsible for the mild vernalisation requirement preventing premature flowering and early heading.

The first, HDCSW-18, was released and officially notified in 2016. Although having a potential wheat yield of over 7 tonnes per hectare – as against 6-6.5 tonnes for existing popular varieties such HD-2967 and HD-3086 – its plants grew to 105-110 cm. Being tall, compared to 90-95 cm for normal high-yielding varieties, made them prone to lodging or bending over when their earheads were heavy with well-filled grains.

The second variety HD-3410, released in 2022, has higher yield potential (7.5 tonnes/hectare) with lower plant height (100-105 cm).

But it’s the third one, HD-3385, which looks most promising. With the same yields as HD-3410, plant height of just 95 cm and strong stems, it is least lodging-prone and most amenable for early sowing. This variety, sown this time at IARI’s trial fields on October 22, has reached pollination stage – while the emergence of the earheads is yet to start for the wheat that was planted in the normal time.

IARI has registered HD-3385 with the Protection of Plant Varieties and Farmers’ Rights Authority (PPVFRA). It has also licenced the variety to the DCM Shriram Ltd-owned Bioseed for undertaking multi-location trials and seed multiplication. “This is our first ever such public-private partnership experiment. By registering the variety with PPVFRA, we are ensuring full protection of our intellectual property rights,” said IARI’s director A.K. Singh.

The director-general of ICAR Himanshu Pathak told The Indian Express that involving the private sector in commercialisation of publicly-bred crop varieties will benefit farmers through faster adoption and diffusion of technology. “It is also beneficial for ICAR because our institutes will earn royalty on every kg of seed sold by the licensee, which they can plough back into research. And the country gains through higher production from climate-smart varieties,” he added.