In a major breakthrough for Nigeria, which is subject to recurrent and devastating flooding, two high-yielding flood-tolerant rice varieties developed by the Africa Rice Center (AfricaRice) – FARO 66 and FARO 67 – have been officially approved for cultivation.
The flood-tolerant varieties were selected based on farmers' rankings and results of on-station, multilocation and on-farm trials conducted in partnership with the National Cereals Research Institute (NCRI) and the National Rice and Maize Center (NRMC).
“For the first time in Nigeria, vulnerable rice farmers in flood-prone areas will have access to this powerful innovation,” said Dr Ramaiah Venuprasad, AfricaRice lowland rice breeder, who led the team that achieved this feat. Rainfed lowlands occupy more than 70% of total rice area in Nigeria and are prone to recurrent flooding caused by heavy rainfall or overflow of nearby rivers.
Yield losses resulting from flooding may range from 10% to total crop loss. In 2012, when Nigeria experienced the worst flooding in 40 years, floods reduced rice production by about 22%. Flooding is expected to be increasingly problematic under global warming, as studies by AfricaRice on future rice climates project massive increases in overall precipitation in north and northwest Nigeria.
Most rice varieties can get severely damaged or killed within a week of severe flooding. “Depending on the intensity of flooding, it can reduce yield, it can prolong the growth duration and in extreme cases, it can cause total crop loss,” said Dr Venuprasad. “We have seen this happen in many places in Nigeria.”
Dr Venuprasad explained that the only possible solution to tackle this problem is the use of flood-tolerant varieties. His team used marker-assisted breeding to introduce into popular Nigerian rice varieties a gene, called ‘SUB1’, which confers to rice plants the ability to tolerate complete short-term submergence.
This technique has been very successfully used in Asia to upgrade popular Asian rice varieties with submergence tolerance. For instance, Swarna-Sub1 (popularly named the ‘scuba rice’) is the first submergence-tolerant high-yielding rice variety developed in Asia that was released in 2009. It is grown by more than 1.3 million farmers in India.
Thanks to the achievement by Dr Venuprasad’s research team, rice farmers in Africa can now benefit from the SUB1 technology. Dr Venuprasad explained that initial efforts to introduce the SUB1 varieties directly from Asia were unsuccessful as these varieties were not locally adaptable. AfricaRice therefore decided to upgrade locally adapted popular rice varieties for submergence tolerance.
Highlighting the advantages of the flood-tolerant varieties developed for Nigeria, Dr Venuprasad said, “Compared to their parents, in addition to submergence tolerance, they have higher yield potential and suitable growth duration and height.” Like their parents, they have good grain quality with medium-long slender grains and are moderately tolerant to iron toxicity.
Under submergence, FARO 66 can yield about 80 times higher than its parent FARO 52, which cannot survive this condition. “This makes FARO 66 a clear alternative for planting in flood-prone areas,” said Dr Venuprasad. Even under non-submergence conditions, FARO 66 showed a yield advantage of about 6-11% in multilocation and on-farm trials. It matures a week earlier than its parent.
Similarly, FARO 67 can yield at least 10 times higher than its parent FARO 60 under submergence. Under non-submergence conditions, FARO 67 showed yield advantage of 10-29% in on-station, multilocation and on-farm trials. It was favored by farmers for its height and larger quantity of biomass that can be used as livestock feed or as mulch to improve crop yields.
The flood-tolerant varieties are thus a result of precision breeding and are not genetically modified organisms. As they provide farmers with protection against short-term flooding and serve as a type of ‘insurance policy,’ farmers can feel reassured and invest in agricultural inputs such as fertilizer, leading to higher rice yields.
Dr Venuprasad gratefully acknowledges that partnership with national agricultural systems such as NCRI and NRMC and with international institutes, such as the International Rice Research Institute (IRRI), has been a key factor in the development of the flood-tolerant varieties for Nigeria.
The work on the development of the flood-tolerant varieties for Nigeria was supported by theBill & Melinda Gates Foundation-funded ‘Stress-tolerant rice for Africa and South Asia’ project led by IRRI. The Asian SUB1 lines from IRRI were used as donor lines of SUB1 gene as part of this project.
The testing of the flood-tolerant varieties in Nigeria was supported by the United States Agency for International Development-funded ‘Seed scaling’ project, the African Development Bank-funded ‘Support to agricultural research for development of strategic crops in Africa’ project and the Bill & Melinda Gates Foundation-funded ‘Rapid mobilization of alleles for rice cultivar improvement in sub-Saharan Africa’ project.
The main challenge now is to produce enough quantities of seed of these varieties and get those seeds quickly into the hands of Nigerian farmers. “There is already a lot of interest in getting seed of the flood-tolerant varieties,” said Dr Venuprasad. A roadmap to multiply and distribute seeds to farmers with the help of government agencies and private seed companies is being developed.
The potential for impact of these flood-tolerant varieties is huge in Nigeria, which is the largest producer of rice in West Africa and the second largest importer of rice in the world. Rice is an important food security crop as well as an essential cash crop in the country.
The submergence-tolerant rice varieties are also being tested through the Africa-wide Rice Breeding Task Force for their adaptability to other African countries that are flood-prone. Five potential flood-tolerant varieties are under testing in Madagascar.
Attaining self-sufﬁciency in rice production is an important goal of many African countries, including Nigeria. The flood-tolerant varieties can contribute to achieving this goal by boosting rice production and helping reduce dependence on costly rice imports.