Run-up to COP26: Wonder rice may help reduce emissions, offer good yield

Scientists in Manila are developing new varieties offering this & much more

Could the wonder rice all paddy farmers hanker for – and which could help save the earth – be around the corner? Scientists in Manila think this goal is within their grasp as they develop new rice varieties offering a good yield, less susceptibility to insects, and lower greenhouse gas emissions.

The Direct Seeded Method (DSR) which has been around for several years is known to be eco-friendly but there were complaints of low yields and increased susceptibility to pests. In response, scientists at the International Rice Research Institute (IRRI) in Manila have come up with rice varieties which not only give higher yields than the traditional puddling method but are also resistant to pests.

The varieties being tested at the IRRI in various agro-climatic zones across Asia not only germinate quickly in extreme dry conditions but also give a yield of around 4-5.5 tonnes per hectare. If the same variety is grown through puddling, the yield level goes up even further to almost seven tonnes per hectare, researchers claim.

The cross-country trials are being conducted across 29 sites in Asia and Africa including India where the first trials are currently close to harvest in states such as Delhi, Uttar Pradesh, Bihar and Odisha.

“Over the last 10 years of research at IRRI, we have identified nine key traits which rice varieties need to be suitable for direct seeding. Lack of these traits leads to poor crop stands, low yields, and eventually slow adoption by farmers despite the numerous benefits of the technology. We are now working on incorporating all of them in one single variety and have so far successfully managed to develop varieties that have 3-4 of these traits in them,” Dr Shalabh Dixit, senior scientist and plant breeder at the IRRI told Business Standard.

The traits which have been identified include faster and quicker emergence of seeds, emergence from deeper soil, adapted to anaerobic germination so that seeds germinate even when the fields are flooded with water, early rigour and fast canopy closure, and resistance to drought at the seedling stage etc. (see chart).

 “We have managed to develop varieties that can germinate within 7-10 days of seeding and have rapid canopy closure to combat weeds.  Weeds are a major problem in dry DSR which is much more pronounced compared to fields where rice is grown through the traditional method where fields are filled with water,” said Dixit.

He said IRRI is targeting high/premium-quality grains which can compensate even if the yields go down.

The trials, which started in 2019 but could not progress satisfactorily due to the pandemic, have reached a critical stage and Dixit believes that if all permissions are granted, then commercial release can happen in the next three to four years.

“Along with new DSR varieties that are being developed, countries also need to follow proper agronomic practices such as ideal seed rate, fertilizer dosages, spacing between lines, etc. Agronomic practices need to go with breeds as a package,” explained Dixit.

He said earlier efforts had focused on eliminating or addressing one or a few problems in DSR varieties. This was the first time that largescale breeding activities have been taken up for addressing all the major components required for DSR adaptation of rice and producing a complete package of traits.

“The new varieties could also address stubble burning as the crop takes less time to mature, giving farmers ample time to do residue management,” he said.

Rice and emissions

It is well known that rice-growing is resource-intensive: rice cultivation covers 11 per cent of the Earth’s arable land and consumes one-third of irrigation water. Perhaps less well-known is that paddy farming is a major contributor to greenhouse gas emissions.

Studies have shown that rice farming across the world could be responsible for up to twice the level of climate impact of previous estimates.

A study published in the Proceedings of the National Academy of Sciences found that intermittently flooded rice farms can emit 45 times more nitrous oxide than continuously flooded farms that predominantly emit methane.

“These emissions contributed substantially to global warming, far more than the estimate of 10 per cent previously suggested by multiple global rice research organizations,” the study found.

DSR Versus Traditional Method

Among the various techniques propagated by scientists to check emissions from paddy, DSR is among the most common.

In DSR, rice seedlings are directly planted into the soil either manually or through machines, doing away with the requirement of first growing the plant in nurseries and then transplanting them into the fields, both of which have to be done in fully watered conditions.

However, despite being in vogue for some years, DSR hasn’t really picked up in the major rice-growing regions of India. One complaint of many farmers is that the yields are sometimes lower than the traditional process of transplanting. Another is that the crop is more prone to pests, weeds, and insects than the traditional method.

In Punjab, around 0.6 million hectares has been brought under DSR rice in the last kharif season. This is the highest so far but just a fraction of the around 2.8 million hectares on which paddy is grown in the state.

Similarly, in neighbouring Haryana, the government has been giving an incentive to farmers to shift from traditional puddling methods to DSR but the uptake has been slow. India grows rice in around 43-45 million hectares and the production varies between 115 to 123 million tonnes. Rice is one the main food grains, both in the kharif and rabi seasons.