Press Release April 2000

More information is available at the IRRI website http://www.cgiar.org/irri)

It has taken more than 20 years. But, in the first months of the new century, Dr. Sant Virmani, plant breeder at the International Rice Research Institute (IRRI), believes that he has, at last, proven his point: hybrid technology is a viable means of boosting rice yields in the tropics. He quotes figures to show the increasing area being committed to hybrids in India (150,000 hectares), Vietnam (200,000 hectares), and Bangladesh (30,000 hectares). Over the past quarter of a century, hybrid rice production in China has grown to cover nearly 16 million hectares, or half the country's total rice-growing area.

Yet it wasn't long ago that Sant Virmani's early research into hybrid rice was dismissed as an impracticable academic exercise. Its critics believed it would fail on simple economic grounds.

Hybrid rice yields about 15 to 20 percent more than the best of the semidwarf inbred varieties upon which the rice crop of tropical Asia depends. But its commercial viability relies totally upon a technically complex process of producing fresh seed for every crop, rather than the conventional system in which farmers simply save seed from their previous harvest.

When Dr. Virmani first began searching for parental lines for hybrid breeding, he was a postdoctoral fellow at IRRI. It was the early 1970s, and popular opinion held that there was no point in developing hybrid technology when there was no expertise for producing the seed, and no money in farmers' pockets to pay for it.

Then, in 1977, Chinese scientists surprised the rice research community by announcing that they'd created commercial hybrid rice varieties for temperate farming, and Dr. Virmani began the research project that would become his life's work.

The hybrid varieties that had achieved rapid success in China were unsuitable for tropical farming and their grain quality was regarded as poor. So, new parental lines had to be developed for the tropics.

More importantly, Dr. Virmani had to convince agricultural scientists in tropical Asia that the difficult task of seed production was within their capacity, and that the higher yields and financial returns of hybrid crops would justify the higher seed costs to small-scale farmers.

"I always believed the technology would be accepted, but I didn't know how long it would take," he says. "At first, I thought it might take five years. Then I added another five years, and another five after that. Finally, I'm running out of people who doubt the technology."

The key, as it turned out, was the adoption of hybrid technology in the free-market economy of India. Others soon followed the Indian example. In 1999, Vietnam, unimpressed with the grain quality of Chinese hybrid varieties, introduced an IRRI variety, and Bangladesh launched its hybrid rice program with IRRI's help.

But despite the clear theory that hybrid technology could provide substantially larger harvests, the obstacles to its adoption by communities of small, poorly educated farmers have been formidable.

A Complex Process

Producing hybrid seed for every crop is a complex process requiring specific genetic technology. It is based on the fact that rice is self-fertilizing; each plant has both male and female elements. So, to cross two genetically different varieties, one of them must be prevented from fertilizing its own seed. In simple terms, the most common method goes like this:

Hybrid breeders first create a rice line that does not produce viable pollen; it is male-sterile. But it can produce seed if pollinated by another line. So, the male-sterile line is multiplied by crossing it with a second line, called the "maintainer." In most respects, this is genetically similar to the male-sterile line except that it can produce viable pollen. The multiplied male-sterile plants are then grown alongside a third variety, which is genetically different. The third variety produces viable pollen to fertilize the male-sterile plants, creating fertile first-filial-generation hybrid seeds.

Breeders must involve a range of parents, and create a diversity of hybrids. The different combinations are evaluated for yield, disease resistance, insect resistance, and grain quality. Only the best are selected. Their seeds are then produced in bulk to supply farmers.

The first-generation offspring from genetically different parents exploit a phenomenon known as hybrid vigor. They perform better than both their parents. They have a larger total biomass than high-yielding inbred varieties and produce more grains per unit area.

But if farmers save and plant the seeds of a hybrid crop, the resulting plants will not be uniform; they will show mixed grain types, and they will have lost their yield advantage. So, new hybrid seeds have to be bought for every crop, and the cost is relatively high.

But Dr. Virmani says that, while seed will add about US$50 per hectare to the cost of farming hybrid rice, the crop will yield as much as 1.5 tons more per hectare and farmers can expect to earn an additional $135 to $200 per hectare.

He says that about 15 commercially usable male-sterile parental lines have now been developed at IRRI for tropical hybrid rice farming. These offer genetic diversity, so that if one or another develops susceptibility to diseases or pests, alternatives exist.

China Offers Help

A big development also occurred in 1999. China, with its years of experience in commercial hybrid production, joined the IRRI-sponsored International Hybrid Rice Network, involving national agricultural research systems in India, Bangladesh, Indonesia, the Philippines, Sri Lanka, and Vietnam.

"With IRRI's expertise in tropical hybrid rice breeding and seed production, and China's expertise in commercial seed production, we'll work together to do great things," Dr. Virmani says. "If any one of the countries just beginning hybrid production recognizes an IRRI rice hybrid that suits local conditions, but they don't know how to organize production of its seed or how to maximize grain yields, then China will be able to step in to assist in commercializing the technology."

He says that the private sector has also begun investing in the development and commercialization of hybrid rice technology. So much so that the Asia-Pacific Seed Association, representing many seed companies in the region, has formed a "special interest group" on hybrid rice.

"I'm very encouraged by the many private companies, both national and multinational, who want to bring their expertise in seed production, marketing, and distribution to the hybrid rice field," Dr. Virmani says. "Many of them also want to invest in hybrid rice by committing their own staff to further research."

He says that IRRI provides parental lines and other materials to both public and private organizations on the understanding that these materials are not intended for their exclusive use.

Researchers at the Institute have even designed a self-sustaining system for individual farmers who wish to produce their own hybrid seed. Some training is required, as well as a small outlay for seeds of the parental lines.

Clear Path Forward

Dr. Virmani expects that over the next five years the Asia-wide momentum of hybrid rice production will become self-sustaining. But the path forward for his research is clear.

In the near future, he says, IRRI's new plant type is expected to produce yields as high as those of the current crops of hybrids. At that stage, his hybrid program will begin using the new plant type as a parental line, and the resulting hybrid vigor is expected to provide yields that are a further 10 to 15 percent above those of the new plant type.

"Then," he says, "we'll be heading up toward yields of 15 tons per hectare, from the same irrigated fields that are currently producing less than 10 tons per hectare with high-yielding inbred varieties."

Another hope in the immediate future is to identify parental lines for the development of hybrid rice suited to rainfed lowland ecosystems.

"I've had to struggle to take every step along the way," Dr. Virmani concludes. "But now, I feel a great satisfaction."

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