Silflower (Silphium integrifolium Michx.) is in the early stages of domestication as a perennial version of oilseed sunflower, its close relative. Grain crops with deep perennial root systems will provide farmers with new alternatives for managing soil moisture and limiting or remediating soil erosion, fertilizer leaching, and loss of soil biota. Several cycles of selection for increased seed production potential following initial germplasm evaluation in 2002 have provided opportunities to document the botany and ecology of this relatively obscure species, to compare agronomic practices for improving its propagation and management, and to evaluate the differences between semi-domesticated and wild accessions that have accrued over this time through intentional and unintentional genetic processes. Key findings include: domestication has increased aboveground biomass at seedling and adult stages; seed yield has increased more, achieving modest improvement in harvest index. Harvest index decreases with nitrogen fertilization. Silflower acquires nitrogen and water from greater depth than typical crops. In agricultural silflower stands within its native range, we found that Puccinia silphii (rust) and Eucosma giganteana (moth) populations build up to unacceptable levels, but we also found genetic variation for traits contributing to resistance or tolerance. Breeding or management for reduced height and vegetative plasticity should be top priorities for future silflower research outside its native range.

Increases in extreme weather events have caused extensive flooding across the United States. In response, federal, state, and local governments have broadened their flood mitigation strategies to include acquisition and demolition of flood-damaged homes (“buyouts”). Little work has documented or analyzed the range of strategies for funding buyouts. Federal programs provide the bulk of funding, but these programs are often slow. Also, state and local governments struggle to meet cost-match requirements. We present and analyze a nationwide census of buyout funding programs (n = 34), which draw on five primary funding mechanisms. We find that state and local governments are using a range of traditional and innovative financial mechanisms, including municipal/green bonds, revolving loan funds, local option sales taxes, and stormwater utility fees, as viable tools for funding buyouts. These tools may promote more autonomy from federal government mitigation programs, and ultimately, faster buyout processes.

Analysis of temperature dependence of the threshold current in 2.3-2.6 μm InGaAsSb/AlGaAsSb quantum-well lasers Appl.A novel waveguide structure to reduce beam divergence and threshold current in GaInP/AlGaInP visible quantum-well lasersThe modification of the electronic bandstructure in a semiconductor, quantum well due to an induced strain is well known. Recently, we have developed a generalized, spectroscopic-based technique for analyzing the strain condition within devices based on quantum wells. This approach couples experimental data describing interband transition energies within strained, quantum-well devices with a rigorous theoretical description of the quantum-well bandstructure. The theoretical formalism is described, and various important theoretical predictions necessary in the application of this method are given. The accuracy of the theoretical model used in this approach is critical to its success, and it is therefore necessary to ensure the validity of the theoretical formalism as applied to quantum wells under a variety of strain conditions. We show the good agreement between theory and experiment for a number of known strain conditions within quantum wells and quantum-well devices. This agreement indicates the validity of the theoretical formalism in the method being described, and the applicability of the method to a wide class of quantum-well based semiconductor devices. A key result in applying this method is the piecewise linearity of the change in interband transition energy with strain for the ranges of strain of interest. The method is then applied to the important case of packaging-induced strain in high-power diode lasers or "cm-bars" as they are sometimes known. Experimental results indicate that the method provides an excellent means of analyzing packaging-induced strain in cm-bars and similar devices.

While root-order approaches to fine-root classification have shown wide utility among wild plants, they have seen limited use for perennial crop plants. Moreover, inadequate characterization of fine roots across species of domesticated perennial crops has led to a knowledge gap in the understanding of evolutionary and functional patterns associated with different fine-root orders. METHODS: We examined fine-root traits of common horticultural fruit and nut crops: Malus ×domestica, Prunus persica, Vitus vinifera, Prunus dulcis, and Citrus ×clementina. Additional roots were sampled from 33 common perennial horticultural crops, native to tropical, subtropical, and temperate regions, to examine variation in 1st-and 2nd-order absorptive roots. RESULTS: First-order roots of grape and 1st-and 2nd-order roots of apple and peach were consistently thin, nonwoody, mycorrhizal, and had high N:C ratios. In contrast, 4th-and 5th-order roots of grape and 5th-order roots of apple and peach were woody, nonmycorrhizal, had low N:C ratios, and were thicker than lower-order roots. Among the 33 horticultural species, diameter of 1st-and 2nd-order roots varied about 15-fold, ranging from 0.04 to 0.60 mm and 0.05 to 0.89 mm respectively. This variation generally was phylogenetically conserved across plant lineages. CONCLUSIONS: Collectively, our research shows that root-order characterization has considerably more utility than an arbitrary diameter cutoff for identifying roots of different functions in perennial horticultural crops. In addition, much of the variation in root diameter among species can be predicted by evolutionary relationships.

Silflower (Silphium integrifolium (Michaux)) is a native North American relative of sunflower that is undergoing domestication as a perennial oilseed crop. As silflower incurs pest damage from multiple insect species, it is necessary to screen genotypes for their effect on insect performance such that more pest tolerant/resistant accessions can be incorporated into future silflower breeding programs. We present a bioassay protocol for silflower using the generalist herbivore fall armyworm (Spodoptera frugiperda (J. E. Smith)). In this study, fall armyworm larvae were placed on leaf and flower tissue from eleven silflower genotypes, one cup plant (Silphium perfoliatum (L.) (Asterales: Asteraceae)) genotype, and an inbred sunflower line (Helianthus annuus (L.) (Asterales: Asteraceae), HA89). Caterpillar weight gained during a 4-d feeding period significantly differed on leaf and floral tissue from different silflower genotypes, between the Silphium species (silflower and cup plant), and between Silphium genotypes and annual sunflower. Two wild silflower genotypes produced lower larval weight gain on both the floral and leaf tissue than all other genotypes, suggesting these genotypes have either lower nutrition or greater resistance to fall armyworm. However, nonsignificant correlations between larval growth on floral versus leaf tissue across all plant species tested and among all silflower accessions suggest insect performances on these tissue types in silflower are independent. Along with identifying germplasm of interest for silflower breeding programs, we established an easily replicable bioassay protocol using fall armyworm on silflower floral and leaf tissues.