Performing Department
(N/A)
Non Technical Summary
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' means 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.
Animal Health Component
0%
Research Effort Categories
Basic
90%
Applied
10%
Developmental
0%
Goals / Objectives
The overarching goal of this project is to study the effects of climate change on global populations of parthenium (Parthenium hysterophorus) through the lens of ecological feedback between the soil, weeds, and crops. This projectwill provide ecological insights into the adaptation of global parthenium biotypes (i.e., 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 addition to guiding the management of parthenium, this projectwill produce general insights into the direct and indirect effects of climate change on invasive agricultural weeds. To this end, this project hasthe following three objectives:Objective 1. Assess the interactive effects of climatic factors on parthenium growth, below-ground interactions, and competition against C3 and C4 crops. The interactive effectsof temperature, moisture, CO2 concentration, and parthenium population (four global populations) on weed and crop morphology, physiology, and yield will be evaluated in a growth chamber experiment. We will also extract allelopathic compounds and conduct microbial analyses to investigate the relationship between allelopathy and microbial activity, including its response to climate change and its effect on crop growth.Objective 2. Investigate how drought modifies parthenium competition against C3 and C4 crops in representative global cropping systems. A common garden experiment will evaluate morphological variation and weedy traits across four global parthenium populations in competition with regionally important C3 and C4 crops grown under dryland and irrigated conditions at five field sites in four representative countries.Objective 3. Incorporate ecological knowledge into existing population dynamics models to improve predictions about climate-driven range expansion across agricultural landscapes. We will use our experimental data to build upon existing population dynamics models, applying ecological knowledge about the nexus of climate change, range expansion, and weed plasticity to better predict threats to US and global cropping systems.
Project Methods
Objective 1. Assess the interactive effects of climate factors on parthenium growth, below[1]ground interactions, and competition against C3 and C4 crops.Experimental design: Parthenium populations will be sourced from four countries representing its native and non-native ranges and grown in competition with a C4 crop (Zea mays, corn) or a C3 crop (Triticum aestivum, spring wheat). The experiment will be arranged in a split-plot design with two 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. The temperature regimes represent low, slightly elevated, and extreme temperatures, respectively, for all three plant species. The experiment will be conducted in controlled-environment growth chambers (Conviron™, Winnipeg, Canada) located at Cornell University, Ithaca, NY. Growth chambers will be maintained at a light intensity of 550 μmol m-2 s -1 PPFD by metal halide lamps with a 14-hour photoperiod. Relative humidity will be maintained at 60±5%. Soil moisture will be tracked throughout the experiment. Within each of 24 climate treatments, there will be five replications of each combination of parthenium population (four levels) and weed-crop competition (two levels) in non-sterile silt loam soil, plus an additional three replications in sterile silt loam soil, for a total of 1,536 5-gallon tree pots. The weed-crop competition treatment will consist of one corn plant in competition with one parthenium plant, or one spring wheat plant in competition with one Parthenium plant. The experiment will be performed two times.Observations: Measurements of Parthenium will include rosette diameter and plant height (recorded at 10-day intervals), time to anthesis and seed maturity, seed yield, as well as the viability, dormancy, and vigor of seeds. When plants transition from vegetative to reproductive growth, LI-6800 (LI-COR Inc, Lincoln, NE) gas exchange measurements will be taken on a subsample of parthenium, corn, and spring wheat plants. Morphological observations of parthenium, corn, and spring wheat will include leaf area index, aboveground biomass, and below-ground (root) biomass. Yield and quality traits, including grain protein, will be measured for corn and spring wheat. To quantify allelochemical levels, parthenin will be extracted from root and shoot tissue for a subsample of parthenium plants. For both non-sterile and sterile silt loam soil, microbial analysis will be conducted via PCR and qPCR and organic carbon (C), microbial biomass nitrogen (N), N mineralization, and total N will be measured. To normalize activity to the size of the microbial community, specific microbial respiration will be calculated as the ratio of SOC decomposition rate (CSOC) to microbial biomass C (MBC). MBC can be determined by the fumigation-extraction method.Statistical analysis: Data will be evaluated by ANOVA in SAS v. 9.4 (SAS Institute, Cary, NC). Tests for normality and homogeneity of variance will be conducted in JMP (JMP©, Version X. SAS Institute Inc., Cary, NC).Expected outcomes: We expect different global parthenium populations exhibit different traits and responses to climate factors, which modify competitiveness against C3 and C4 crops under different climate scenarios. We also expect that measuring allelochemical concentrations and microbial activity in non-sterile and sterile soil will reveal connections between climate, weed-crop competition, and below-ground biochemical interactions. This data set will be the first to connect the aboveground growth and competitiveness of parthenium with rhizosphere interactions in the context of global climate change. These data will also contribute to the expansion of a population dynamics model.Objective 2. Investigate how irrigation modifies parthenium competition against C3 and C4 crops in representative global cropping systems. Field study design: This will be a multi-location common garden field study carried out with the support of global collaborators in Ithaca, NY, US; College Station, TX, US; Brisbane, Queensland, Australia; Coimbatore, Tamil Nadu, India; and Ramat-Yishay, Israel. The study will be conducted in a split-plot design and repeated over two growing seasons. The main plots will represent irrigation treatment (2 levels: dryland versus irrigated conditions) with sub-plots for parthenium populations (4 levels: US, Australia, India, Israel) and weed-crop competition level (2 levels: C3 crop or C4 crop). Thus, there will be 16 treatment combinations replicated three times for a total of 48 plots. Plots will be 8.5 meters wide by 9.1 meters long. Each location will select C3 and C4 crops that are regionally important and potentially threatened by parthenium. Parthenium seed will be broadcast-planted prior to the first field season.Observations: At the start of the growing season, four 2 m2 quadrats will be established within each plot. Every three weeks throughout the growing season, weed and crop plant heights, NDVI, SPAD meter values (Spectrum Technologies, Aurora, IL), and R:FR ratio at the canopy level (Apogee Instruments, Logan, UT) will be measured within quadrats. Additionally, the time to anthesis and seed maturity and percentage seed shattering will be measured. At harvest, measurements for weed and crop plants within quadrats will include leaf area index, plant aboveground biomass, and below-ground (root) biomass. Yield and quality traits, including grain protein, will be measured for crop species. We will also note any differences between parthenium traits in the first growing season (F0 generation) and the second growing season (F1 generation). Expert global collaborators will perform data collection according to a shared protocol and communicate regularly to ensure that methodology does not differ among common garden locations.Statistical analysis: Treatment effects will be evaluated by ANOVA, as described under Objective 1.Expected outcomes: Novel physiological, ecological, and agronomic knowledge from this global-level common garden experiment will help inform the population dynamics model and provide potentially generalizable insights into plant invasiveness. Such differences may reflect plasticity and/or the first step in adaptation to a novel environment.Objective 3. Incorporate ecological knowledge into existing population dynamics models to improve predictions about climate-driven range expansion. The effects of increasing temperatures on invasive weed distributions have been modeled for multiple species, including parthenium. Many of these models identify potentially invasive regions by comparing the climates of already-invaded areas to the current (or projected future) climates within other regions of the world, and no such research has been undertaken in the US. A smaller number of "process-based" or "mechanistic" models incorporate ecological or physiological data. Incorporating more ecological knowledge into models can improve predictions about the future distributions and impacts of invasive species. We will build upon an already existing model in the R environment that projects population distribution of parthenium under climate change scenarios (Dorji et al., 2021) with the collaboration and expertise of Sangay Dorji and Dr. Steve Adkins (University of Queensland, Australia) and Dr. Bagavathiannan (Texas A&M University). This model is openly available for public use. Parameter values estimated from the growth chamber and field experiments, including life history traits and weed-crop interactions, will be input factors for the model. The updated model will be used to predict climate-driven northward range expansion of parthenium populations from the southern US locations.