Location: Crops Pathology and Genetics Research
2011 Annual Report
1)Develop technologies to quantify real-time remotely accessible measurements of vineyard-scale evapotranspiration and vine water use; and.
2)Development and expansion of commercially available grapevine rootstocks that better resist drought and tolerate salinity. For objective 1, structure functions are used to study the dissipation and inertial range scales of turbulent energy, to parameterize remote turbulence measurements, and to characterize ramp features in the turbulent field. The ramp features are associated with turbulent coherent structures, which dominate energy and mass fluxes in the atmospheric surface layer. The analysis of structure functions for identifying the ramp characteristics is used in surface renewal (SR) methods. It is unclear how different scales of coherent structures (i.e., smaller ramps embedded in larger ramps) that are commonly observed in data influence structure function analysis. To date, we have examined the effects of multiple ramp scales on structure functions and their analysis by using both artificially generated multi-scale ramp series and high frequency temperature observations from above bare ground and two types of short plant canopies. We used structure function lags ranging in scale from isotropic to larger than the characteristic turbulent coherent structures and spectral analysis of structure functions to detect different scales of coherent structures. The frequencies of the coherent structure scales increase with mean wind shear, but the size of the scales relative to one another is fairly constant. Our new objective method for obtaining SR based scalar exchange works well over bare ground and short canopies under unstable conditions, and should form the foundation for analysis over taller and more complex surfaces. For objective 2, our ARS lab is collaborating with a UC Davis researcher (Dr. Walker). Our research team also completed an initial screen of southwestern US Vitis species for reduced chloride uptake following our new greenhouse methods. The screen included 113 individual genotypes collected from low elevation and semi-arid locations in the southwestern US. Preliminary results identified several plants from different species that display lower leaf chloride content than either Ramsey or St. George, the typical low-uptake benchmarks, confirming accessions from this group of species have breeding potential. This work is being paired with hydraulic physiology measurements. We have just initiated similar experiments to complete these measurements on new parent material (i.e. Vitis arizonica, candicans, rupestris, and berlandieri) from arid regions of the southwestern United States.