Location: Plant Science Research2013 Annual Report
1a. Objectives (from AD-416):
1. Assess and parameterize for models, the effects of changing temperature, vapor pressure, atmospheric carbon dioxide and ozone on crop performance. (Booker, Fiscus, Burkey) 1.A. Design and construct an air exclusion system for treating crops with elevated ozone, elevated temperature and elevated atmospheric carbon dioxide concentrations. 1.B. Assess and parameterize for crop growth models (DSSAT-CSM -CROPGRO-Soybean and DSSAT-CSM-CERES-Wheat), the effects of elevated ozone, temperature and carbon dioxide on soybean and wheat physiology, above and belowground growth and development, yield and seed quality. 1.C. Characterize interactive effects of temperature, vapor pressure, carbon dioxide and ozone on plant growth in outdoor controlled environment systems. 2. Characterize the effects of the major climate change variables temperature, atmospheric vapor pressure, carbon dioxide, ozone and possible interactions on the infection rates and progression of the disease in plants infected with wheat rust. (Fiscus) 3. Identify soybean germplasm that will contribute to development of stress tolerant cultivars. (Burkey, Booker) 3.A. Identify soybean cultivars with enhanced ozone tolerance. 3.B. Characterize the inheritance of ozone tolerance in soybean ancestors. 4. Identify the mechanisms through which soil microorganisms mediate perennial grasses, forage legumes and ecosystem responses to changing climate conditions. Develop economically sustainable production systems for forage and biomass crops that reduce the net emissions of greenhouse gases per unit of forage or biomass production. The research will contribute to the ARS GRACEnet project.
1b. Approach (from AD-416):
Experiments will be conducted in available open top field chambers, greenhouse exposure chambers, and custom Outdoor Plant Environment Chambers (OPECs) or in a new air exclusion system to be developed by this project that allow for testing of plant responses to combinations of carbon dioxide and ozone under contrasting conditions of temperature and vapor pressure deficit. A multi-year field study will be established using the air exclusion system to test the effects of elevated ozone, temperature and carbon dioxide on a soybean-winter wheat continuous no-till cropping system. Detailed assessments of plant growth, biomass, and yield along with measurements of leaf gas exchange, tissue chemistry and micrometeorological data will be used as inputs for parameterization of DSSAT-CSM CROPGRO-Soybean and CERES-Wheat models. Ozone-sensitive and tolerant snap beans will be grown in the OPECs where control of relative humidity and temperature allows for the study of plant responses to elevated ozone and carbon dioxide under contrasting vapor pressure deficit conditions. Wheat cultivars that are susceptible and resistant to stripe or stem rust will be grown in the OPECs and inoculated with pathogens under a range of carbon dioxide, ozone, temperature and vapor pressure deficit conditions to examine the potential impact of these climate change factors on infection and progression of disease. Soybean germplasm will be exposed to elevated ozone conditions in greenhouse exposure chambers or open-top field chambers and foliar injury and seed yield measurements used to identify tolerant cultivars. Single nucleotide polymorphism markers will be applied to a soybean population developed from a cross between ozone-sensitive and tolerant soybean ancestors and the population screened for ozone-induced foliar injury in the greenhouse. Marker and phenotype data will be combined to develop a map of soybean ozone-tolerance genes.
3. Progress Report:
Additional improvements were made in our Air Enrichment System (AES), an exposure system designed to provide a clean-air (charcoal-filtered) environment along with elevated temperature, ozone and CO2 treatments in field plots. The original passive solar heating units were replaced with additional water-to-air solar heat exchangers so that each heated plot now has a total of four heat exchangers in addition to the electrical resistance heating system. Experience to date suggests that the current design will provide an elevated temperature treatment of 3.5 to 4.5 degrees Celsius above ambient conditions. Replacement of the passive solar units significantly reduced the “foot print” of each plot so that the field can now accommodate additional experimental plots. AES heated plots are being compared with AES controls and ambient air plots in a replicated soybean study in 2013. The irrigation approach will target common soil moisture content across all plots, replacing simulated uniform rainfall events, to compensate for greater water usage in heated plots and reduce confounding effects of temperature and drought. Harvest and environmental data are being collected for use in a crop growth computer model. Four wheat varieties with different levels of susceptibility/resistance to wheat leaf rust, Puccinia triticina, were vernalized and grown under combinations of elevated carbon dioxide and ozone in our outdoor plant environment chambers. Optimized temperature and relative humidity conditions provided conditions to facilitate pathogen infection and development on plants. Disease latency and intensity, foliar symptoms caused by both ozone and pathogen infection, biomass, seed yield and seed quality were measured. Preliminary assessment of the data suggests there are significant interactions between genotype, gas treatment, and pathogen infection. Mapping ozone tolerance genes in soybean was advanced for a population of 240 recombinant inbred lines derived from a cross between Fiskeby III (ozone-tolerant) and Mandarin Ottawa (ozone-sensitive) genotypes. Single nucleotide polymorphism DNA markers were used to construct the linkage map. Data from screening of the population for ozone-induced foliar injury were finalized and formatted for quantitative trait loci (QTL) analysis. Mapping software was used to identify QTLs for ozone response on chromosomes 1 and 18. A project SY took an active role in leading an agroforestry experiment at the Center for Environmental Farming Systems in Goldsboro, NC. The experiment was established in 2007 and has a factorial design of three tree species (Pinus palustris, Pinus taeda, and Quercus pagoda) and two alley widths (12 and 24 m) with five replications. New research efforts were initiated, including (a) managing the integrated crop-animal component of the Farming Systems Research Unit in Goldsboro, NC and (b) collaborating in an on-farm research and demonstration effort with Cotton Incorporated and North Carolina State University to test cover crop impacts in cotton production on soil organic matter accumulation and alleviation of soil compaction.