Assessment of Genetic Gain Trends for Yield in IRRI Rice Varieties in the Philippines Using “era” Trial Studies and Implications for Future Rice Breeding

Abstract Rice is a staple crop for 3.5 billion people in the world. To meet the challenges of the rice production for food security and demand due to population increase, yield improvement due to a rice variety’s genetic characteristics is imperative. Two studies presented in this paper were undertaken at the International Rice Research Institute (IRRI) in the Philippines, to assess genetic gains for yield in rice varieties bred over the past 50 years. These studies are called as “Era” studies as the varieties used for trials were released during long and distinct periods. Due to the differences in time periods of studies, varieties and locations, the studies were treated separately so as to not to compromise the data analyses. The studies demonstrated that IRRI developed varieties have achieved genetic gains and levels of genetic gains were dependent on correction or otherwise for maturities. In Study 1, the highest level of genetic gain was 0.70% at about a 23 kg ha-1 annual yield increase when not corrected for maturity followed by a genetic gain of 0.62% when corrected for maturity. In Study 2, the highest level of genetic gain was 0.74% at about a 19 kg ha-1 annual yield increase when corrected for maturity followed by 0.66% genetic gain when not corrected for maturity. Implications for breeding programs are discussed, however, the studies were not intended to compare genetic gains achieved through different breeding methods nor to compare genetic gains achieved using plot trials versus realized genetic gains for crops grown under farmers’ management.