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Dhaka Tribune

Mega rice varieties becoming less productive, pest susceptive

Bangladesh urged to go for varietal replacement soon

Update : 22 Apr 2022, 12:21 AM

For over the past three decades two mega rice varieties – BRRI dhan28 and BRRI dhan29 – were the mainstay of Bangladesh’s pursuit of rice self-sufficiency. Among over a hundred modern rice varieties that Bangladesh rice breeders developed over the last 50 years, these two highly productive varieties stole the show by outperforming most of the others.

After gaining popularity among millions of rice growers in Bangladesh, these two varieties expanded to the extent that in recent years 70% of the country’s Boro rice fields came under the coverage of just these two varieties – BRRI dhan28 and BRRI dhan29.

Caution was sounded yesterday, after an arduous and vigorous joint on-farm comparative trial by Bangladesh Rice Research Institute (BRRI) and the International Rice Research Institute (IRRI), that Bangladesh needs to urgently go for varietal replacement in rice to protect its future food security.  

The worrisome news is that BRRI dhan28 is now becoming less productive and more susceptible to pest attacks while BRRI dhan29 is getting infected by neck blast disease. But the good news is Bangladeshi rice scientists have by now developed better breeds like BRRI dhan88, 89 and 92, which give good yields and are less susceptible to diseases and pests.

BRRI and IRRI scientists have made an urgent call to replace the popular mega rice varieties with promising newer breeds in quick time so that future rice productivity is not compromised.  

Dr Swati Nayak, IRRI South Asia lead for Seed System and Product Management Platform, told Dhaka Tribune yesterday: “Varietal replacement is crucial. We’ve to do it on a regular basis.”

Talking to this correspondent on the sidelines of a workshop on the issue, the IRRI scientist emphasized making farmers aware about the rice varietal replacement and having seeds of the recently developed better rice breeds available to them.

Dr Nayak said rice was predominantly being grown by small and marginal farmers in this part of the world, people who were resource poor and who needed to be reached by effective agricultural extension service so that they could switch to newer promising varieties sooner rather than later.

BRRI released the two mega rice varieties – BRRI dhan28 and BRRI dhan29 – back in the early 1990s and these have already seen their best days of their most productive cycle. They are now in a process of degeneration and need to be replaced by better available options.

Dr Swati Nayak said that for short duration, best yield potential for “Rainfed Lowland Rice-Short Duration” (RLR-SD) ecosystem are BRRI dhan71, Binadhan-17 and Binadhan-22, which can replace old varieties like Binadhan-7, BRRI dhan39, and BRRI dhan33.

For “Rainfed Lowland Rice-Long Duration” (RLR-LD) ecosystem, BRRI dhan94, BRRI dhan79 and BRRI dhan87 can replace old varieties like Swarna, and BR 11.

For a short duration, the best yield potential is BRRI dhan88, BRRIdhan81 and BRRI dhan96, which can replace the mega old variety BRRI dhan28.

For longer duration BRRI dhan92, BRRI dhan89 showed the highest yield advantages over the mega variety BRRI dhan29 across all the divisions.

A chief scientific officer, Dr Md Humayun Kabir heads the Adaptive Research Division (ARD) of BRRI. Speaking from experience and the outcome of comparative yield potential trials over the past three/four years, Dr Kabir noted that BRRI dhan28 gave the lowest yield having highest pest incidence that should be replaced immediately.

“BRRI dhan29 produced a competitive yield along with BRRI dhan89. However, it was infected by neck blast disease in some locations,” Dr Md Humayun Kabir added. 

According to him, BRRI dhan58 has had good potential throughout the country, except in the eastern parts of Bangladesh, while BRRI dhan67 performed excellently throughout the country. 

The workshop was told that BRRI dhan88 has been found to be the best yield performer of all tested varieties while the new potential variety BRRI dhan89 produced a better yield than the old mega variety BRRI dhan29. 

With an annual rice output in excess of 36 million tons, Bangladesh has emerged as the third top rice producer in the world after China and India and yet it has to import one to two million tons of rice each year to manage the demand-supply gap. 

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