**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** AGRICULTURAL CLIMATE ADAPTATION BECOMES INCREASINGLY IMPORTANT IN A SITUATION WHERE WEEDS CAN ADAPT FASTER THAN CROPS, AGGRESSIVELY COMPETE FOR RESOURCES, AND SHIFT INVASIVE RANGES ACROSS AGRICULTURAL LANDSCAPES. ARABLE WEEDS IMPOSE THE MOST YIELD LOSSES TO GLOBAL CROP PRODUCTION AMONG ALL CROP PESTS, AT AN AVERAGE OF 34%, WHICH EQUATES TO ECONOMIC LOSSES OF $27 BILLION PER YEAR FOR UNITED STATES (US) PRODUCERS. A WEED SPECIES OF GLOBAL SIGNIFICANCE ACROSS 50 COUNTRIES, PARTHENIUM (PARTHENIUM HYSTEROPHORUS), CAN REDUCE CROP YIELD AND FORAGE PRODUCTION BY 47-90%. WHILE THE NATIVE RANGE OF PARTHENIUM INCLUDES THE SUBTROPICAL AMERICAS TO THE SOUTHERN US, WITH EXISTING REPORTS ORIGINATING PRIMARILY FROM TEXAS AND FLORIDA, ANECDOTAL EVIDENCE SUGGESTS RANGE EXPANSION INTO THE SURROUNDING REGIONS IN THE US. NATIVE AND INVASIVE PARTHENIUM POPULATIONS HAVE EXHIBITED DIFFERENTIAL GROWTH RESPONSE TO CO2 AND CLIMATE FACTORS. THE NORTHERN RANGE EXPANSION OF INVASIVE WEEDS IS ALSO EXPECTED TO BE FACILITATED BY A WARMING CLIMATE AND CHANGING PRECIPITATION PATTERNS. THE RISKS OF PARTHENIUM RANGE EXPANSION AND ESTABLISHMENT FOR US AGRICULTURE ARE NOT WELL UNDERSTOOD, BUT GLOBAL PARTHENIUM POPULATIONS INDICATE DIRE ENVIRONMENTAL AND ECONOMIC IMPACTS.THIS RESEARCH WILL PROVIDE ECOLOGICAL INSIGHTS INTO THE ADAPTATION OF GLOBAL PARTHENIUM BIOTYPES FROM THE US, AUSTRALIA, INDIA, ISRAEL TO CLIMATE CHANGE BY 1) UNCOVERING CLIMATE INTERACTIONS DRIVING ABOVEGROUND AND BELOWGROUND WEED-CROP COMPETITION IN A GROWTH CHAMBER STUDY, 2) IDENTIFYING ADAPTIVE WEEDY TRAITS IN IRRIGATED/DRYLAND CROPPING SYSTEMS REPLICATED ACROSS FIVE GLOBAL FIELD ENVIRONMENTS, AND 3) LINK ECOLOGICAL AND CLIMATE DATA TO POPULATION DYNAMICS MODELS TO PREDICT RISK OF RANGE EXPANSION FOR US AGRICULTURE. IN THE FIRST EXPERIMENT, PARTHENIUM POPULATIONS WILL BE SOURCED FROM TEXAS, US, AUSTRALIA, INDIA, AND ISRAEL TO BE GROWN IN COMPETITION WITH EITHER WHEAT OR CORN PLANTS UNDER STIMULATED CLIMATE-STRESS SCENARIOS. GROWTH AND REPRODUCTIVE PARAMETERS OF PARTHENIUM AND CROP PLANTS WILL BE OBSERVED IN GROWTH CHAMBERS WITH DIFFERENT COMBINATIONS OF CO2 LEVELS (450 PPM AND 700 PPM) AS THE MAIN TREATMENT, THREE TEMPERATURE LEVELS (20/15°C, 30/25°C, AND 45/40°C DAY/NIGHT) AS SUB-TREATMENTS NESTED WITHIN CO2, AND FOUR SOIL MOISTURE LEVELS (FIELD CAPACITY, 75% FIELD CAPACITY, 50% FIELD CAPACITY, AND 25% FIELD CAPACITY) NESTED WITHIN TEMPERATURE. UNLIKE MOST PREVIOUS INVESTIGATIONS INTO AGRICULTURAL WEED ADAPTATION TO CLIMATE CHANGE, OUR RESEARCH WILL ALSO INVESTIGATE MICROBIALLY-MEDIATED EFFECTS OF CLIMATE CHANGE ON BELOW-GROUND PROCESSES AND THEIR POTENTIAL RELEVANCE TO WEED-CROP COMPETITION. IN THE SECOND STUDY, THE COMPETITIVE AND REPRODUCTIVE POTENTIAL OF GLOBAL PARTHENIUM POPULATIONS WILL BE EVALUATED UNDER IRRIGATED VERSUS DRYLAND CROPPING SYSTEMS AT FIELD SITES IN TEXAS, US, NEW YORK, US, AUSTRALIA, INDIA, AND ISRAEL AS A 'COMMON GARDEN EXPERIMENT.' A 'COMMON GARDEN EXPERIMENT' ME,ANS EACH OF THE GLOBAL PARTHENIUM POPULATIONS WILL BE GROWN CONCURRENTLY AT EACH FIELD SITE ALONGSIDE REGIONALLY IMPORTANT CROPS (I.E. CORN, SOYBEAN, WHEAT) TO EVALUATE THE LEVEL OF WEED-CROP COMPETITION AND ADAPTIVE TRAITS OF NATIVE VERSUS FOREIGN PARTHENIUM POPULATIONS ACROSS VARIOUS ENVIRONMENTS OVER A TWO-YEAR PERIOD. AS EXPERIMENTAL ECOLOGICAL DATA IS NOT ALWAYS INCLUDED IN CLIMATE MODELING EFFORTS, IN THE FINAL COMPONENT OF THIS RESEARCH WE WILL BUILD UPON AN ALREADY EXISTING POPULATION DYNAMICS MODEL WITH OUR ECOLOGICAL DATA TO PREDICT RANGE EXPANSION IN US CROPPING SYSTEMS. PREVENTION OF UNDESIRABLE INVADERS IS THE MOST COST-EFFECTIVE STRATEGY AS ERADICATION OFTEN BECOMES UNFEASIBLE ONCE COLONIZING WEED POPULATIONS ESTABLISH IN A NEW TERRITORY. WE EXPECT THAT THIS ECOLOGICAL FRAMEWORK FOR A POPULATION DYNAMICS MODEL, WITH PARTHENIUM AS A MODEL SPECIES, WILL RESULT IN MORE INFORMED RISK-MANAGEMENT OF INVASIVE WEED RANGE EXPANSION IN US CROPPING SYSTEMS AND DEVISE ECOLOGICALLY-INFORMED STRATEGIES TO NEGATE CROP VULNERABILITIES. ULTIMATELY, THIS RESEARCH WILL PROVIDE RECOMMENDATIONS FOR PARTHENIUM THAT CAN BE IMMEDIATELY IMPLEMENTED IN US CROPPING SYSTEMS; INFORM WEED RISK ASSESSMENTS FOR OTHER REGIONS AND WEED SPECIES; AND DEVELOP A NOVEL FRAMEWORK TO INTEGRATE KNOWLEDGE ABOUT RANGE SHIFTS, PHENOTYPIC PLASTICITY, ADAPTIVE EVOLUTION, AND RHIZOSPHERE INTERACTIONS IN THE CONTEXT OF CLIMATE CHANGE.

Cornell University, Ithaca NY

Investigators