Making rice less thirsty

 Lanie C. Reyes   |  
(Photo: IRRI)

(Photo: IRRI)

Since the dawn of agriculture, drought has been the bane of farmers, especially  who grow rice, a crop that has special water requirements. Drought stress severely limits rice productivity in the rainfed ecosystem in which farmers often experience total crop failure because of a lack of water at one critical plant growth stage or another, according to Arvind Kumar, a plant breeder at the International Rice Research Institute.

Most rainfed areas receive a reasonable amount of rainfall during the growing season. “However,” says Dr. Kumar, “its erratic distribution and shortage, particularly at flowering and again at grain-filling, can seriously curtail productivity.” He adds that Asia alone has around 23 million hectares (20% of the total rice area) that are prone to drought under these conditions and where climate change may make matters, particularly water scarcity, only worse.

Without assured irrigation, farmers are completely dependent on rainfall to water their crops. The possibility of drought has made rice farming a risky endeavor. Because of the risk, farmers do not invest enough in inputs to increase rice production.

To help farmers cope with water scarcity, IRRI has bred several new lines that are as high-yielding as any normal varieties with sufficient water. They have a 0.8 to 1 ton per hectare yield advantage whenever drought occurs. Two of these drought-tolerant breeding lines have been recommended for official release: IR74371-70-1-1 in India and its sister line IR74371-54-1-1 in the Philippines.

“IRRI has intensified efforts to develop drought-tolerant and aerobic cultivars to cope with this looming water shortage,” says David Mackill, leader for IRRI’s rainfed program. “Drought has been a
complex trait to improve, and I am very happy to see the recent advances and progress in developing drought-tolerant lines at IRRI.”

Most farmers in rainfed/drought-prone areas grow varieties bred for irrigated conditions such as IR36, IR64, Poornima, MTU1010, Lalat, Swarna, and Sambha Mahsuri, among others. Unfortunately,  these varieties are highly susceptible to drought.

Whenever a severe drought occurs, these irrigated varieties suffer high losses and farmers are lucky to harvest even half a ton per hectare from them.

“With the cultivation of the newly bred drought-tolerant lines, in normal rainfall years, farmers will have the same high yield of irrigated varieties, and in drought years they can harvest 1.5 to 2 tons from 1 hectare,” says Dr. Kumar.

IRRI works with the national agricultural research and extension systems (NARES) for the evaluation of newly developed breeding lines.

Before a breeding line is identified for release, it undergoes testing in the national system and is recommended for release after its superior performance in the national trials.

The newly developed drought-tolerant lines IR74371-70-1-1 and IR74371-54-1-1 outperformed the current varieties in national trials in India and the Philippines and have been recommended for release for farmers’ cultivation.

The two breeding lines also performed well under aerobic and alternate wetting and drying (AWD) situations (see The big squeeze, and Every drop counts).

IRRI’s System for Temperate and Tropical Aerobic Rice project under the Challenge Program for Water and Food has been building a network on participatory varietal selection (PVS) testing and evaluation since 2004. The project aims to develop prototype aerobic rice production systems for water-scarce environments.

According to Ruben Lampayan, water management scientist at IRRI, a major component of the project was to identify rice varieties with high yield potential under aerobic conditions from among IRRI’s advanced lines through PVS. They tapped their project partners to collaborate in implementing PVS with farmers.

In the Philippines
Dr. Lampayan has found in Junel B. Soriano, director for research, extension, training, and production at Bulacan Agricultural State College (BASC), the heart and passion to reach out to more partners and stakeholders with aerobic rice and other water-saving technologies. Hence, in the Philippines, IR74371- 54-1-1 has been tested at BASC since 2004 and in farmers’ fields in Bulacan, La Union, Bataan, and Palawan since 2006.

Dr. Soriano recalls a time during the dry season of 2004 when a trial was conducted in a small testing plot at BASC in coordination with IRRI. They invited farmers, technicians, and researchers during the PVS. During that PVS, one impressed farmer eagerly asked, “Can I reproduce that line on my farm?” That farmer was Nemencio Concepcion, 49, of San Ildefonso, Bulacan. He became interested in the drought-tolerant variety because it seemed tailor-made for his drought-prone upland area.

On his own initiative, he reproduced the line and was happy with the results. His neighboring farmers were eager to try it on their farms. Eventually, the line became popular among farmers, and is known among them as “5411” (instead of IR74371-54-1-1).

According to Dr. Soriano, 5411 matures 2 weeks ahead of their previously used variety, which takes 120 days to mature. The new line yields an average of 4.5 tons per hectare. Also, it is very resistant to pests and diseases and, so far, farmers have not experienced tungro or any other disease. Mr. Concepcion proudly announces that the rice he planted in February was harvested in May. “Because of its shorter duration, it allows me to harvest not just two but three times a year,” he says. “And, as this variety is tolerant of drought, I can plant the crop even during the dry season without any fear of crop loss.”

Since his farm is on higher ground, he needs to pump in water. With AWD technology, he is thankful that he does not need to flood his paddies. He pumps water only a few times a month and only when necessary. “I save much on water and on gasoline for the pump, even during the dry season,” Mr. Concepcion says. His recent crop experienced more than 2 weeks of drought. So, he pumped water to his upland rice area. However, there was one rice area where he was not able to pump water because of insufficient available water. “I sacrificed that area and accepted its fate because the rice plants wilted already,” he stated. But, when rain came, he was surprised to see that his plants recovered from wilting. Although the rice that recovered from drought is expected to be harvested about 2 weeks later than the rest of the 5411, it is still within an acceptable duration. Above all, he is just glad to be able to harvest rice despite the drought. (For drought-susceptible varieties, more than 2 weeks of drought in upland fields may yield almost nothing for farmers.)

Mr. Concepcion’s experience is consistent with what Dr. Kumar says about the new drought-tolerant lines: “They withstand drought at any stage of the crop cycle. Moreover, they withstand drought even at the reproductive stage, when the plant suffers more loss due to drought.”

“Since that line can be broadcast-seeded instead of transplanted, I saved a lot on labor costs,” relates Mr. Concepcion. “I don’t need to hire laborers to plant seedlings in the nursery, pull them from the seedbed, tie them together, and transplant them.”

Every harvest, Mr. Concepcion earns around US$638 to $850 per hectare from his rice field (of 4 ha) planted with 5411. Mr. Concepcion is indeed one happy and satisfied farmer. His influence on other farmers to adopt 5411 reaches Nueva Ecija and Pampanga provinces. Even if rice fields in these areas are irrigated, there is no problem because 5411 still performs well in wet areas. According to Dr. Soriano, Mr. Concepcion is so effective in influencing other farmers to adopt 5411 and increase the productivity of their lands that he considers Mr. Concepcion not just a farmer cooperator but a partner in BASC’s extension efforts.

Mr. Concepcion was one of the first 13 farmer cooperators in 2004. They increased to 50 in 2005, to 70 in 2006, and BASC now has more than 100 farmer cooperators. According to Dr. Soriano, the success of adoption can be attributed to farmer-to-farmer influence and support from the local government. Dr. Soriano is more than encouraged in sharing the benefits of 5411 along with its management technologies, the aerobic system, and the AWD system in the Philippines, because he believes that more farmers can benefit from all this, particularly those in rainfed areas.

He plans to expand extension activities at BASC by involving other state universities and colleges all over the country. He has started to coordinate with other state universities such as Bataan Polytechnic State University, Palawan State University, and Mindanao Foundation College, among others.

In eastern India
Similarly, in eastern India, IRRI introduced a drought-tolerant breeding line, IR74371-70-1-1, which has also consistently performed well both at research centers and in farmers’ fields. Since eastern India is one of the largest drought-affected areas, a variety that can cope with a dry spell is a welcome change in rice farming.

IR74371-70-1-1 was initially tested under an India-IRRI collaborative project, the Drought Breeding Network (DBN), whose partners are the Central Rainfed Upland Rice Research Station (CRURRS) in Hazaribag; Indira Gandhi Krishi Vishwa Vidyalaya, Raipur; Birsa Agricultural Univ., Ranchi; Narendra Dev University of Agriculture and Technology, Faizabad; Tamil Nadu Agricultural University, Coimbatore; University of Agricultural Sciences, Bangalore; and Barwale Foundation, Hyderabad, India. Courtesy of the DBN, researchers have identified this entry as promising for the drought-prone ecosystem. Since this line is a product of a joint endeavor, the team from CRURRS suggested the name Sahbhagi dhan, which means, in Hindi, “rice developed through collaboration.” Recently, the Variety Identification Committee (VIC) recommended it for release to the Central Subcommittee on Crop Standards, Notification, and Release of Varieties.

Nimai P. Mandal, a plant breeder at CRURRS, tested Sahbhagi dhan during the wet season of 2004. It has consistently performed well, better than any other entries of that duration, since then. “In 2007, we started testing this variety in farmers’ fields in two villages near Hazaribag,” he says. Kailash Yadav, 34, and Naresh Paswan, 38, of Mahesha, Hazaribag, Jharkhand, are two farmers who had the opportunity to observe a demonstration using Sahbhagi dhan conducted by CRURRS and they tried it on their respective farms. As a result, they were delighted to harvest 4.5 tons of rice per hectare in a good monsoon year. Before using the drought-tolerant variety, they harvested only 3 to 3.7 tons per hectare. They are also pleased with its traits such as the ability to tolerate a month-long drought, early maturity, and good eating quality.

Farmers in rainfed areas such as Mr. Yadav and Mr. Paswan largely depend on rain for a good harvest. But, good years may be few and as unpredictable as the onset of drought. If the rains are poor, this can spell catastrophe for all. Mr. Yadav still remembers the 2006 drought that affected their village. Without any income from farming, he somehow managed some earnings from his small grocery store. But, many villagers migrated to town to work as daily laborers. One was Mr. Paswan. Though he describes the drought CRURRS (2) 14 Rice Today July-September 2009 Mr. Shashikant Yadav (left), CRURRS agricultural field assistant, interviews Mr. Naresh Paswan (center) and Mr. Kailash Yadav (right), farmers who have tested Sahbhagi dhan on their farms. as “not so severe,” it still affected the people of his village. Finances were so difficult then that he needed to borrow money from another farmer for his transportation.

Sahbhagi dhan gave the two farmers opportunity and hope in rice farming. “I have confidence that this variety will be a blessing for farmers in drought-stress situations,” says Mr. Paswan. “And, we can manage the problem of drought by growing this variety,” adds Mr. Yadav. Because both are impressed by the qualities of Sahbhagi dhan, they are going to recommend it and share it with their neighbors as soon as they have sufficient seed. “Drought-tolerant lines have received high farmers’ preference scores in both normal and drought trials and farmers look convinced of adopting such superior varieties,” says Dr. Stephan Haefele, IRRI soil scientist and agronomist who is responsible for testing the lines in farmers’ fields under PVS in India. More farmers besides Mr. Paswan and Mr. Yadav will benefit from Sahbhagi dhan. According to Dr. Mandal, the rainfed upland area in India occupies about 6 million hectares. But the target area for Sahbhagi dhan could be more because it is also suitable for drought-prone shallow lowlands. U.S. Singh, the regional coordinator for South Asia of the Bill & Melinda Gates Foundationsupported project on “Stress-tolerant rice for poor farmers in Africa and South Asia” and responsible for seed production and dissemination of Sahbhagi dhan, plans to have large-scale seed multiplication of this line in 2009 and produce 100 tons of seed to distribute to as many farmers as possible by the next wet season in India.

National Food Security Mission of India, National Seed Corporation, various public- and private-sector seed corporations and companies, research organizations, and NGOs are interested in reproducing and disseminating Sahbhagi dhan seeds. “Our purpose is to take this variety to the maximum number of farmers in the shortest possible time,” says Dr. Singh. As the scientist now responsible for developing droughttolerant varieties, Dr. Kumar says that he is very lucky to witness the success of this teamwork.

When asked whether this is his greatest accomplishment as a scientist, he says, “This is IRRI’s achievement. Other scientists before me have been working for about 40 years to achieve this.” Dr. Brigitte Courtois attempted the crosses, which had led to the development of these two lines. And it was Dr. Gary Atlin, who introduced the concept, initiated and conducted experiments on direct selection for grain yield under drought stress. He combined high yield potential under irrigated situation with good yield under drought.

Forty years? What turning point along the way led to high-yielding drought-tolerant rice? IRRI scientists started working in a different way: working directly on improving grain yield in rice under drought. Dr. Rachid Serraj, a drought physiologist involved in dissecting the mechanisms of drought tolerance and its genetic variation in rice, says that combining high yield potential and drought tolerance through direct selection for grain yield is one of the right approaches for developing drought-tolerant lines, in addition to marker-assisted selection (see On your mark, get set, select on pages 28-29 of Rice Today Vol. 3 No. 3) and GM (genetic modification) approaches (see Overcoming the toughest stress in rice: drought on page 30).

In the years before that, scientists had been working on improving the traits thought to be related to drought tolerance such as leaf rolling, rooting depth, and other traits. They believed that yield under drought could be increased by improving these secondary traits. In 2004, IRRI breeders started to work on direct selection for grain yield under drought stress. At first, they were not sure that this would show results. But, subsequent experiments confirmed that this approach worked.

For a plant breeder like Dr. Kumar, “developing drought-tolerant cultivars is the most efficient way to stabilize rice production in drought-prone areas.” Higher yield of drought-tolerant lines in drought years should encourage farmers to apply more inputs such as fertilizer that further raise the productivity of the rainfed drought-prone system. Because of drought-tolerant lines, farmers will indeed lower their risks of investing their money and time in drought-prone areas.

Sahbhagi dhan and 5411 and other similar drought-tolerant lines that may be developed in the future will benefit and provide confidence to rice farmers not just in India and the Philippines but also in other droughtprone areas in Asia, Africa, and other parts of the world. In fact, a few other promising drought-tolerant lines and aerobic cultivars are now being tested in India, Bangladesh, Nepal, and the Philippines under projects supported by the Bill & Melinda Gates Foundation, Rockefeller Foundation, Generation Challenge Program, and Asian Development Bank.

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