Z.H. He,1 M. van Ginkel,2 L. Gilchrist,2 and S. Rajaram2 1CIMMYT-China, c/o Chinese Academy of Agricultural Sciences 2CIMMYT, Mexico

Introduction

Fusarium head blight or head scab of wheat is a major disease in China, particularly in the Autumn-sown Spring Wheat Zones in the Middle and Low Yangtze Valleys and Southwestern China located in the Yangtze region, and the Northeast Spring Wheat Zone. About 7 million ha of Chinese wheat area is affected by head scab, and developing scab-resistant cultivars has been the major breeding objective in these areas.

Chinese wheat confers good resistance to head scab, and Sumai 3 is used worldwide as a resistance source, but its yield potential and agronomic performance need further improvement. On the other hand, CIMMYT wheats have short stems and good lodging resistance, high yield potential, good rust resistance, and acceptable quality. However, they are poorly adapted to humid Chinese environments and susceptible to head scab and leaf wilting.

In the mid 1980s, CIMMYT and China initiated a shuttle breeding and germplasm exchange program focusing on incorporating the scab resistance of Chinese wheats into high yielding CIMMYT germplasm. A formal agreement was signed between CIMMYT and the Chinese Academy of Agricultural Sciences (CAAS) in 1988. The target area has expanded greatly since 1995, and most major provincial agricultural academies have started cooperating with CIMMYT. This paper describes the progress of this joint project in terms of germplasm exchange and development, information exchange, and training.

Germplasm exchange and development

At CIMMYT, progress in breeding for scab resistance has built largely on the use of Chinese germplasm. In the last 15 years, around 700 Chinese commercial varieties, advanced lines, and important scab resistant wheats (such as Sumai 3, Ning 7840, Shanghai 3, Shanghai 4, Shanghai 5, Suzhou 6, Wuhan 3, and Chuanmai 18) have been sent to CIMMYT. A set of resistant bread wheat lines with good agronomic performance have been developed at CIMMYT through the use of Chinese germplasm, as reported by Gilchrist et al. (1997).

In general, two types of crosses, Chinese/CIMMYT and Chinese/CIMMYT//CIMMYT, are used in Mexico when using Chinese germplasm to improve wheats for other countries and mega-environments. However, in CIMMYT crosses directed towards China, crosses are Chinese/CIMMYT//Chinese or sometimes CIMMYT/Chinese//Chinese. Currently, Chinese wheat can be found in the pedigrees of more than 50% of CIMMYT germplasm for high rainfall environments (ME2).

In addition to scab resistance, Chinese spring wheat also shows good resistance to Karnal bunt, helminthosporium leaf blotch, tan spot, and septoria diseases. A large number of CIMMYT Chinese crosses are made each year, and many Chinese derivatives are included in CIMMYT's international nurseries distributed throughout the world. The most outstanding CIMMYT bread wheat crosses under different mega-environments (MEs) with Chinese germplasm in their pedigrees are presented below. They have shown good adaptation to locations outside Mexico.

More than 10,000 CIMMYT lines have been distributed to 40 Chinese wheat breeding programs, either in the form of regular international nurseries and special nurseries such as F3YZ and F3CHENGDU, or materials selected by Chinese visiting scientists in Mexico. In China, three-way cross of Chinese/CIMMYT//Chinese is employed. The following varieties directly evolved from the shuttle breeding project have been released in China. Presently, 5-7 million ha are cultivated to varieties carrying CIMMYT germplasm in their pedigree. Ningchun 4 and Xinchun 6 are the leading varieties in the Northwestern Spring Wheat Region and Xinjiang, respectively. In addition to that, good quality wheats such as Longmai 26, Zhongyou 9507, Jinan 17, and Liaochun 10 have quality conferred by CIMMYT wheats.

In the 1999-2000 season, CIMMYT's China Office has offered three regional nurseries in China. Each nursery will consist of advanced lines and newly released varieties as well as introductions from other countries. To fulfill the need for quality improvement, two quality wheat nurseries have also been distributed.

Human resources development

From 1985 to 2000, CIMMYT sponsored visits to Mexico by 95 Chinese scientists for a period from three weeks to one year. Fifty-six Chinese scientists have participated in the wheat improvement and cereal quality training courses, which last from two to eight months. CIMMYT has also supported the attendance at international conferences of more than 30 Chinese scientists. These opportunities have enhanced their scientific skills and improved their understanding of CIMMYT's wheat breeding methodology. Currently, most training alumni and visiting scientists have been appointed to lead the wheat breeding program in their own institutes, and several have been promoted to directors of their institutes.

Demonstration plots with wheat lines produced by China/CIMMYT shuttle breeding, ready to be released.

Information exchange

Chinese scientists receive many CIMMYT publications, and CIMMYT provides a channel for Chinese scientists to understand wheat breeding in other countries. The following CIMMYT publications have been published in Chinese. CIMMYT has also published three Wheat Special Reports on subjects related to Chinese wheat.

In addition to publications, CIMMYT and CAAS have also jointly organized several wheat breeding meetings and training courses, as presented below. They have greatly enhanced scientific exchange between CIMMYT and Chinese wheat breeding programs.

References

He, Z.H. and S. Rajaram, editors. 1997. China/CIMMYT Collaboration on Wheat Breeding and Germplasm Exchange: Results of 10 Years of Shuttle Breeding (1984-94). Wheat Special Report No 46. Mexico, D.F.: CIMMYT.

Dubin, H.J., L. Gilchrist, J. Reeves, and A. McNab, eds. 1997. Fusarium Head Scab: Global Status and Future Prospects. Mexico, D.F.: CIMMYT.

Gilchrist, L., Rajaram, S., and Crossa, J. 2000. New sources of scab resistance and breeding progress at CIMMYT. In: Raupp, J.W., Ma, Z., Chen, P., and Liu, D. (eds.). Proceedings of the International Symposium on Wheat Improvement for Scab Resistance. 5-11 May, 2000. Suzhou and Nanjing, China. pp. 194-199.

© CIMMYT July 2001

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