Impact of International Germplasm Exchange on Rice Varietal Improvement.

Since 1975, more than 24,000 unique breeding lines and varieties from national research systems and international research centers have been exchanged multilaterally among rice scientists from >80 countries through the IRRI-coordinated International Network for Genetic Evaluation of Rice (INGER).  Assembled as >51,000 entries in nurseries or trials targeted for different rice ecosystems (45%) and biotic (39%) and abiotic stresses (16%), 673 outstanding materials were selected and released as varieties in 66 countries.  Top recipients of breeding materials (>1,000 unique lines) were China, India, Thailand, Bangladesh, and South Korea while top providers (>1,000 lines) were India, Indonesia, Bangladesh, Thailand, and South Korea.  Numerous materials were used as parents in making >18,000 crosses for developing new varieties.  For example, at least 224 of the 836 varieties (27%) released nationally and in 24 states in India have at least one INGER parent. In China, 10 released hybrids used INGER entries directly as restorers while 24 popular hybrids were developed from restorers derived from INGER materials.  In Bangladesh, Indonesia, Malaysia, and Sri Lanka, countries with moderately strong rice breeding programs, 38 of 45 (84%), 30 of 78 (41%), 8 of 25 (32%),  and 18 of 48 (38%) of national varietal releases, respectively, used at least one parent introduced from other countries.  Relatively young breeding programs such as those of Cambodia, Myanmar, and Nepal benefited tremendously, with 19 of 37 (51%), 44 of 71 (46%), and 28 of 44 (63%) of their varieties being direct releases.  A similar impact was generated in Africa – 250 INGER materials were released directly as varieties, and 60 of 78 (77%) of the NERICA varieties released/adopted by farmers by 2007 were derived from IRRI breeding lines, including 55 NERICA varieties tracing back to IR64.  A reinvigorated rice germplasm exchange program typified by INGER is vital for anchoring another Green Revolution.