Multi-site tests environments and breeding strategies for new rice technology

UNDER A LIMITED RANGE OF CONDITIONS, RICE VARIETIES OF THE IR8 PLANT TYPE PERFORM BETTER THAN OTHER VARIETIES, BUT THESE FIRST-GENERATION MODERN VARIETIES CANNOT WITHSTAND THE ENVIRONMENTAL STRESSES IN MANY RICE-GROWING AREAS. THE SECOND-GENERATION MODERN VARIETIES ARE DISEASE- AND INSECT-RESISTANT, BUT THEY STILL DO NOT ADAPT TO A WIDE RANGE OF ENVIRONMENTAL CONDITIONS. THIS SUGGESTS THE NEED FOR DIFFERENT TYPES OF VARIETIES AND DIFFERENT APPROACHES IN PRODUCING THEM. MANY SCIENTISTS BELIEVE THAT ENVIRONMENT-SPECIFIC VARIETIES SHOULD BE PRODUCED. THEY ARE ATTEMPTING TO DEVELOP A MORE PRECISE DEFINITION OF RICE ENVIRONMENTS IN TERMS OF WATER DEPTH, SOILS, RAINFALL, AND TEMPERATURE. THE PAPER FOCUSES ON GAP I -- THE GAP ATTRIBUTED TO DIFFERENCES BETWEEN FARMER ENVIRONMENTS AND ENVIRONMENTS AT EXPERIMENT STATIONS. IN MANY INSTANCES THE GAP IS QUITE WIDE. TO BETTER UNDERSTAND WHY THE GAP EXISTS, THIS PAPER EXAMINES THE GENERAL STRATEGY BEING FOLLOWED BY RICE BREEDERS, THE ENVIRONMENTS IN WHICH RICE IS GROWN IN ASIA, AND THE USE OF MULTILOCATION TESTING PROGRAMS FOR EVALUATING BREEDING MATERIALS. SOME CONCLUSIONS ARE PRESENTED CONCERNING THE INTERRELATIONSHIPS OF NETWORKS, ENVIRONMENTS, AND BREEDING STRATEGIES FOR NEW TECHNOLOGY.