Site Description for the University of Nebraska's Sandhills Agricultural Laboratory

The Sandhills Agricultural Laboratory is operated by the University of Nebraska. The laboratory is located in the south-central part of the Nebraska Sandhills near Tryon, Nebraska (41 deg. 37' N; 100 deg. 50' W). The laboratory is surrounded on the west and south by native rangeland vegetation, on the south by a large field of corn irrigated by a center pivot, and on the east by wheat stubble. This site is appropriate for moisture stress studies since rainfall is almost always inadequate to meet evaporative demands of agricultural crops during most of the growing season and the sandy soils (Valentine fine sand) at the site do not store large quantities of water. Various levels of water stress are achieved through irrigation from solid set sprinklers

Evaluation of AIS Data for Agronomic and Rangeland Vegetation: Preliminary Results for August 1984 Flight over Nebraska Sandhills Agricultural Laboratory

Since 1978 scientists from the Center for Agricultural Meteorology and Climatology at the University of Nebraska have been conducting research at the Sandhills Agricultural Laboratory on the effects of water stress on crop growth, development and yield using remote sensing techniques. We have been working to develop techniques, both remote and ground-based, to monitor water stress, phenological development, leaf area, phytomass production and grain yields of corn, soybeans and sorghum. Because of the sandy soils and relatively low rainfall at the site it is an excellent location to study water stress without the necessity of installing expensive rainout shelters. The primary objectives of research with the airborne imaging spectrometer (AIS) data collected during an August 1984 flight over the Sandhills Agricultural Laboratory are to evaluate the potential of using AIS to: (1) discriminate crop type; (2) to detect subtle architectural differences that exist among different cultivars or hybrids of agronomic crops; (3) to detect and quantify, if possible, the level of water stress imposed on the crops; and (4) to evaluate leaf area and biomass differences for different crops

Platinized tin oxide catalysts for CO2 lasers: Effects of pretreatment

Platinized tin oxide surfaces used for low-temperature CO oxidation in CO2 lasers have been characterized before and after reduction in CO at 125 and 250 C using ion scattering spectroscopy (ISS) and X ray photoelectron spectroscopy (XPS). XPS indicates that the Pt is present initially as PtO2. Reduction at 125 C converts the PtO2 to Pt(OH)2 while reduction at 250 C converts the PtO2 to metallic Pt. ISS shows that the Pt in the outermost atomic layer of the catalyst is mostly covered by substrate species during the 250 C reduction. Both the ISS and XPS results are consistent with Pt/Sn alloy formation. The surface dehydration and migration of substrate species over surface Pt and Sn appear to explain why a CO pretreatment at 250 C produces inferior CO oxidation activities compared to a 125 C pretreatment

Evaluation of inbred maize lines for aluminum tolerance in nutrient solution.

A number of plant measurements were evaluated for their ability to differentiate genotypes for Al tolerance in nutrient solution culture. The best traits proved to be seminal and adventitious root lengths. On this basis, Brazilian inbred lines were shown to be more tolernat of Al than those from the USA. In most lines, root lengths decreased as the Al concentrations used, but in some Brazilian lines root length was unaffected. Al tolerance increased if P was included in the nutrient solution. The combination of 185 umol P/litre in the nutrient solution was the best for evaluationg genotypes for Al tolerance

Inheritance of aluminum tolerance in maize.

In a set of 3 experiments, a number of parental lines and various of their hybrid and backcross generations (from crosses of tolerant and sensitive lines) were raised in nutrient solution containing 195 umol Al/litre. An analysis of relative seminal root lengths showed than additive gene effects contributed most to genetic variation in Al tolerance, with dominance effects accounting for only half as much varation. Epistatic effects were minor. The frequency distributions of tolerance in the F2 were typical of a quantitatively inherited trait. There was a tendency for non-tolerance to be dominant over tolerance although this was not consistent. Analysis of the F1 from a diallel cross among 8 inbred lines indicated that general combining ability variance explained most of the variation, but specific combining ability effects were significant in each case