DORMANT SEEDS MAY SURVIVE IN SOIL OVER YEARS, RESULTING IN THE PERSISTENCE OF WEEDS IN CROPLANDS. WEEDY RICE (ALSO KNOWN AS RED RICE,ORYZA SATIVA) HAS STRONG SEED DORMANCY AND IS A DIFFICULT-TO-CONTROL WEED IN THE SOUTHERN CENTRAL UNITED STATES (US), AND THE WORLD. RECENTLY, MANY POPULATIONS OF RED RICE IN THE RICE-GROWING STATES HAVE GAINED THE HERBICIDE RESISTANCE CONFERRED BY A NON-GE GENE ESCAPED FROM CLEARFIELDTM(CL) RICE. THIS PROJECT AIMS TO ELUCIDATE ECOLOGICAL GENETIC MECHANISMS OF SEEDBANK LONGEVITY (SL) AND PROVIDE FUNDAMENTAL KNOWLEDGE TO MONITOR AND CONFINE THE DISPERSAL OF GENETICALLY ENGINEERED (GE) OR NON-GE CROPS. PREVIOUS RESEARCH HAS IDENTIFIED AND CLONED QUANTITATIVE TRAIT LOCI (QTL) CONTROLLING SEED DORMANCY (SD) IN RED RICE. THE OBJECTIVES OF THIS RESEARCH ARE TO EVALUATE EFFECTS OF THE SD LOCI ON SL IN A CL BACKGROUND, IDENTIFY NEW SL QTL, AND MODEL GENOTYPE-BY-ENVIRONMENTAL INTERACTIONS (G&TIMES;E) IN TILL AND NO-TILL CROPPING SYSTEMS. PLANT MATERIALS DEVELOPEDFOR THIS RESEARCH INCLUDE ISOGENIC LINES FOR NINE SD LOCI, 400 RECOMBINANT INBRED LINES DERIVED FROM A US LINE OF LONG-AWNED BLACK-HULLED WEEDY RED RICE, AND INTROGRESSION LINES OF SD GENES IN A CL BACKGROUND. SEED BURIAL TRIALS AND SUBSEQUENT GERMINATION TESTS IN RICE FIELDS WILL BE USED FOR THE GENE EFFECT EVALUATION, QTL IDENTIFICATION, AND G&TIMES;E MODELING.EXPECTED OUTCOMES INCLUDE THE MAGNITUDE OF SD'S EFFECTS ON SL, NEW GENES FOR SL, AND SURVIVABILITY PROFILES OF SEEDS BURIED IN DIFFERENT SOIL LAYERS FOR VARYING PERIODS. THIS NEW INFORMATION WILL BE USED TO INFORM THE LIKELIHOOD FOR FERALITY OF GE CROPS, SURVIVABILITY OF GE ORGANISMS IN SOIL SEEDBANKS, AND IMPROVED TILLAGE PRACTICES TO CONFINE GE GENES. THIS PROPOSAL FITS IN WITH THE PROGRAM AREA METHODS TO MONITOR AND UNDERSTAND THE DISPERSAL OF GE ORGANISM WITH A SPECIFIC FOCUS ON SEED DORMANCY IN CROPS, SEXUALLY COMPATIBLE WEEDS AND THEIR HYBRIDS.