Spring-seeded smother plants for weed control in corn and soybeans

Smother plants are specialized cover crops developed for their ability to suppress weeds and may provide an alternative, non-chemical method of weed control. The goal of this project was to define the characteristics and mechanics of establishing a successful spring-seeded smother plant system and to study and exploit the competitive interactions among weeds, smother plants, and the crop

Planting Method and Fertilization Timing Effects on Ridge-Till Corn

Fertilizer application technology has improved fertilizer use efficiency in ridge-till systems, but little work on planting methods and application timing within these systems has been done. A study was conducted to evaluate corn (Zea mays 1.) response to injected nitrogen (N) fertilizer applied to different planting methods at common application times. The performance of the late spring soil nitrate and the basal stalk nitrate tests was examined within these systems. A continuous corn and a corn-soybean [Glycine max (1) Merr.] rotation were used in 1989-1991 at two Iowa locations on Nicolett and Monona series soils, line-loamy, mixed, mesic Typic Hapludolls and line-silty, mixed, mesic Typic Hapludolls, respectively. Whole plot treatments were: 1) till planting with fertilizer N applied at layby; 2) slot planting with fertilizer N applied at planting; and 3) slot planting with fertilizer N applied at layby. Subplot treatments (0, 22, 45, 90, 157, and 224 kg N ha-1) were imposed on the whole-plots. The late spring soil nitrate test had consistently low values relative to the scale used for N fertilizer recommendations. The basal stalk nitrate test identified optima nitrate concentrations relating to N fertilizer rates which produced maximum yields. Whole plot treatments generally did not differ significantly in grain yield. Alternative methods of fertilizing corn, such as the use of point injection application equipment, provide opportunities in fertilizer N management that current recommendation tools may enhance

Environmental Benefits and Management of Small Grain Cover Crops in Corn-Soybean Rotations

These slides offer research results on cover crops

Weed Seedbanks and Seedling Emergence in a Two and Three Crop Narrow Strip Intercropping/Rotation System

Weed populations in agronomic settings are, in part, a reflection of the cropping system utilized. The goal of this project was to gain an understanding of the weed population dynamics in a narrow strip intercropping (NSI) rotation by assessing the weed seedbank, weed emergence, and seedling establishment over the growing season for a corn-soybean (two-crop), and a corn-soybean-oat+berseem clover (three-crop) system. Field research was conducted in 1994 and 1995, near Nashua, IA, and each crop was grown m 4.6 m wide strips. Giant foxtail and total weed seed densities were significantly lower in the three-crop NSI rotation system than in the two-crop system. NSI rotation system affected total preplant weed emergence. Preplant density ranged from 103 to 433 weeds m-2 in the two-crop system, while density ranged from 3 to 99 weeds m-2 in the three-crop system. There were no consistently significant differences in weed seedling emergence after crop planting due to NSI rotation system when individual species were examined. Changes in Iowa cropping systems may result from a better understanding of these system dynamics

Ultrashort Laser Pulse Interactions With Matter - New Effects and Spectroscopic Applications

Contains research summary and reports on four research projects.Joint Services Electronics Program (Contract DAAL03-86-K-0002)Joint Services Electronics Program (Contract DAALO3-89-C-0001

Tissue-specific regulatory network extractor (TS-REX): a database and software resource for the tissue and cell type-specific investigation of transcription factor-gene networks

The prediction of transcription factor binding sites in genomic sequences is in principle very useful to identify upstream regulatory factors. However, when applying this concept to genomes of multicellular organisms such as mammals, one has to deal with a large number of false positive predictions since many transcription factor genes are only expressed in specific tissues or cell types. We developed TS-REX, a database/software system that supports the analysis of tissue and cell type-specific transcription factor-gene networks based on expressed sequence tag abundance of transcription factor-encoding genes in UniGene EST libraries. The use of expression levels of transcription factor-encoding genes according to hierarchical anatomical classifications covering different tissues and cell types makes it possible to filter out irrelevant binding site predictions and to identify candidates of potential functional importance for further experimental testing. TS-REX covers ESTs from H. sapiens and M. musculus, and allows the characterization of both presence and specificity of transcription factors in user-specified tissues or cell types. The software allows users to interactively visualize transcription factor-gene networks, as well as to export data for further processing. TS-REX was applied to predict regulators of Polycomb group genes in six human tumor tissues and in human embryonic stem cells

Homeotic Evolution in the Mammalia: Diversification of Therian Axial Seriation and the Morphogenetic Basis of Human Origins

Despite the rising interest in homeotic genes, little has been known about the course and pattern of evolution of homeotic traits across the mammalian radiation. An array of emerging and diversifying homeotic gradients revealed by this study appear to generate new body plans and drive evolution at a large scale.This study identifies and evaluates a set of homeotic gradients across 250 extant and fossil mammalian species and their antecedents over a period of 220 million years. These traits are generally expressed as co-linear gradients along the body axis rather than as distinct segmental identities. Relative position or occurrence sequence vary independently and are subject to polarity reversal and mirroring. Five major gradient modification sets are identified: (1)--quantitative changes of primary segmental identity pattern that appeared at the origin of the tetrapods ; (2)--frame shift relation of costal and vertebral identity which diversifies from the time of amniote origins; (3)--duplication, mirroring, splitting and diversification of the neomorphic laminar process first commencing at the dawn of mammals; (4)--emergence of homologically variable lumbar lateral processes upon commencement of the radiation of therian mammals and ; (5)--inflexions and transpositions of the relative position of the horizontal septum of the body and the neuraxis at the emergence of various orders of therian mammals. Convergent functional changes under homeotic control include laminar articular engagement with septo-neural transposition and ventrally arrayed lumbar transverse process support systems.Clusters of homeotic transformations mark the emergence point of mammals in the Triassic and the radiation of therians in the Cretaceous. A cluster of homeotic changes in the Miocene hominoid Morotopithecus that are still seen in humans supports establishment of a new "hominiform" clade and suggests a homeotic origin for the human upright body plan