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All hyped up for hybrid rice?

Hybrid rice panicle (A.Javellana, IRRI)
Hybrid rice panicle
A.Javellana, IRRI

More than half of the total rice area (31 million ha) in China is currently planted to hybrid rice, and by the end of 2002 it was estimated that a further 800,000 hectares of hybrid rice were planted in Bangladesh, India, Indonesia, Myanmar, the Philippines and Vietnam. China, the world's most populous country, is also the world's largest producer of rice but, as consumption begins to outstrip production, China has begun to import rice from Thailand and Vietnam. As China's population growth continues and its agricultural land-base declines, can China meet its future requirements for rice? Chinese scientists, led by Professor Yuan Longping, otherwise known as the 'Father of Hybrid Rice', believe that it can. Hybrid rice varieties have already greatly contributed to China's food security; the average yield of hybrid rice is 7 t/ha, about 1.4 t/ha higher than that of inbred varieties. But further research is in progress to take hybrid rice one step further to 'super' hybrid rice varieties, which could be capable of producing over twice the yields of traditional inbred varieties.

Hybrids in grain crops such as maize are well known but, as a self-pollinating crop, rice has proved more difficult to hybridise. However, identification of a male sterility gene in a variety of wild rice, followed by successful transfer of the gene, allowed Chinese scientists to create the first three-line hybrids in 1974 and then later, with advances in hybrid rice technology, two-line hybrids which were even more productive. Yields from hybrid rice are double those of non-hybrid varieties, although critics of hybrid rice production assert that much of the increase in China is a result of increased pesticide and fertiliser applications. FAO, however, claims that, as a result of almost thirty years of successful commercial hybrid rice production, China has been able to diversify production on millions of hectares of land and to feed more than one billion people.

Branching out

In the Philippines, ambitious targets set by the Department of Agriculture to increase hybrid rice production to 200,000 hectares by the end of 2003 have failed. It is estimated that not even half this area is currently cultivated with hybrid rice. A shortage of hybrid rice seed has been quoted as one reason for not being able to meet the increased cultivation targets, which may be assisted by Syngenta's recent announcement to commercialise its own hybrid rice seed by September 2004. The Filipino Bureau of Plant Industry is currently evaluating three varieties, including two developed for Syngenta and one by the Philippine Rice Research Institute, PhilRice. However, it is possible that poor uptake of hybrid rice could be attributed to farmers' difficulty in adapting to the precision technology required for cultivating the hybrids.

Outside Asia, however, after recommendations were made by the International Rice Commission for the introduction of hybrid rice to Egypt, FAO reports that these new varieties have performed well in saline conditions yielding 35 per cent more than inbred varieties. Hybrid rice varieties are also being tested and developed in several countries within Latin America.

A far superior hybrid?

As hybrid rice varieties begin to spread across and out of Asia, Chinese scientists remain committed to raising the productivity of the crop. Since a 'super rice' research programme was established in 1996, several pioneer varieties have been developed to produce record yields - in one area in 1999 of up to 17 t/ha. By 2002, the area planted to super rice varieties within China was 1.4 million hectares producing an average yield of 9.1 t/ha, and in 2004 the area under these varieties is expected to double. Meanwhile, efforts are being focused on developing a second-generation super hybrid rice with a yield target of 12 t/ha, which has already been achieved in five pilot areas in Hunnan Province in 2003. If these results could be replicated over a wider area, Chinese scientists are convinced that many more people could be fed, although they concede that growing these super varieties proves more difficult for small-scale farmers as they have yet to be educated in improved irrigation, weeding and fertilising techniques.

Professor Yuan Longping has made a life-long commitment to rice breeding in China and this year his pioneering work has been recognised with the award of the World Food Prize. The success of his work will outlast his lifetime. And yet, at the age of 74, his dedication remains steadfast as he looks to progress from the painstaking traditional cross-breeding of hybrid varieties to the possibilities of genetic engineering to fulfil his vision that higher yielding rice varieties will help to eliminate hunger from the world.

Date published: July 2004

 

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