Location: Plant Science Research
2011 Annual Report
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.
Drought stress studies are difficult because of the unpredictability of rainfall events. We developed the "water stress field", a form of precipitation exclusion technology, for the multiple purposes of studying the physiology of water stress, comparing genetic lines for desirable water stress characteristics and to examine the interactions between soil moisture levels and the toxic effects of ambient atmospheric ozone. The 2008 and 2009 data were used to develop a model for soybean predicting leaf conductance from measurements of soil volumetric water content in the profile down to 40 cm. Coupled with ambient ozone measurements a flux based risk assessment model, based on soil moisture is also being developed.
Five wheat varieties with different levels of susceptibility/resistance to the wheat stripe rust pathogen, Puccinia striiformis, were vernalized and grown under combinations of elevated CO2, ozone, and atmospheric vapor pressure deficit. Ozone significantly damaged the growth and seed production of all five varieties. CO2 promoted growth and lessened the effects of ozone. Vapor pressure deficits were too low to allow for rust development in the leaves. A second experiment in open-top chambers, 60 varieties of wheat, barley, and oat juvenile plants were shown to vary widely in response to ozone exposure, with oat and barley varieties exhibiting greater leaf discoloration than wheat.
Open-top chamber studies were initiated to test the feasibility of identifying ozone-tolerant soybean cultivars based on pedigree analysis. Two ozone-tolerant soybean ancestors, two cultivars genetically related to the tolerant ancestors, and two ozone-sensitive ancestors are being compared using season long exposures to four different ozone concentrations ranging from sub-ambient to twice current ambient levels. Ozone responses are being evaluated in terms of foliar injury, seed yield, and antioxidant metabolism.
Final steps were completed in the development of a soybean population to map stress tolerance genes for drought, iron deficiency chlorosis, ozone, salt, and toxic soil aluminum. The mapping population consists of 240 random inbred lines developed from a cross between Fiskeby III and Mandarin Ottawa plant introductions. Seed increases were completed and initial screening of the population for ozone, drought and iron deficiency chlorosis begun. DNA for use in marker aassays was extracted from leaf tissue for approximately 90% of the random inbred lines.
Cheng, L., Booker, F.L., Burkey, K.O., Tu, C., Shew, H.D., Rufty, T., Fiscus, E.L., Hu, S. 2011. Soil microbial responses to elevated CO2 and O3 in a nitrogen-aggrading agroecosystem. PLoS One. 6:e21377.
Niyogi, D., Mera, R., Xue, Y., Wilkerson, G., Booker, F.L. 2011. The use of Alpert-Stein Factor Separation Methodology for climate variable interaction studies in hydrological land surface models and crop yield models. In:Factor Separation in the Atmosphere:Application and future prospects. Book Chapter. P. Alpert and T. Sholokhman, editors., Cambridge University Press. p. 171-183.