Farmers in Asia welcome the new water-proof Scuba rice variety

"Scuba rice" which can survive for more than two weeks of complete submergence under water can now be planted by farmers to improve rice yields on flood-prone land in the Indian state of Uttar Pradesh where the variety Swarna-Sub1 has been officially approved and other states are expected to follow soon.

ICRISAT's (International Crops Research Institute for the Semi-Arid Tropics) Rice Today's April-June 2009 edition features the remarkable development of the submergence-tolerant rice that has been warmly accepted by farmers in India and Bangladesh, whose flood-prone land could previously not be used for reliable rice production.

Even after 17 days of submergence in IRRI (International Rice Research Centre) research plots, Sub1 rice lines showed their "waterproof" trait and are set to make a big impact in South Asia.

This variety of rice responds by increasing the pace of its elongation in an attempt to escape the submergence. Deepwater rice varieties are able to do this rapidly enough to succeed. In modern high-yielding varieties, however, the elongation is insufficient. If the flood lasts for more than a few days, the normal varieties expend so much energy trying unsuccessfully to escape that they're unable to recover.

In 1991, Dr Mackill, scientist, left IRRI for the University of California (UC) at Davis. He along with his graduate student, Dr Xu, eventually pinpointed the precise stretch of DNA that made the then flood resistant variety, FR13A, so interesting, and named the assumed gene SUB1. The two teamed up with UC Davis researcher, Pamela Ronald, an expert in isolating genes that give plants particular traits. Working in Dr Ronald's lab, Dr Xu and his wife, Xia, discovered a single gene, which they named SUB1A, and demonstrated that this alone was responsible for most of the flood tolerance. Dr Mackill returned to IRRI then with his team was able to transfer SUB1A into a widely grown modern rice variety without affecting other characteristics - such as high yield, good grain quality, and pest and disease resistance - that made the varieties popular in the first place.

According to Dr Mackill, the Sub1 project has shown the advantage of combining practical, applied work such as breeding and upstream, fundamental research. In neighboring Bangladesh, rice farmers also experience the benefits of applying practical research solutions such as adopting shorter duration rice varieties, direct seeding, and weed control to help overcome monga, the hunger months.


In Bangladesh and India, farmers suffer annual crop losses because of flooding of up to 4 million tonnes of rice - enough to feed 30 million people. To the farm families and workers, and to the poor consumers who rely on rice for the bulk of their food, flooding can be disastrous. BRRI's (Bangladesh Rice Research Institute) director general, A Mohammad Firoze Shah Shikder, said that successful flood-tolerant rice could substantially reduce, if not eliminate, the country's imports. Sub1 varieties will add to the total production of the country," he added, "They will save a lot of money that would otherwise be used for importing rice."

IRRI is also sharing its science results digitally through its presence on Google Book Search, flicker (a photo management facility) and YouTube.
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