Identifying drought tolerant short rotation coppice willows

Short rotation coppice (SRC) willows are of interest as they provide a source of renewable carbon for bioenergy and biofuels. One of the major challenges facing future supply of willow biomass is sustaining sufficient yields in drought challenged environments, with research in this area limited to date. The effects of drought responses on Salix germplasm were studied in two pot experiments in a rain out shelter at Rothamsted Research using a split plot design. In both experiments, plants were subjected to two water treatments, drought stressed or well-watered. A temporary water stress was imposed by applying two cycles of drought within a growing season. Experiment 1 aimed to screen 56 diverse Salix genotypes, including subsets of existing genetic mapping populations, to identify potentially informative germplasm for further study in a more focused second pot experiment. Experiment 2 contained 36 genotypes from two willow full-sibling genetic mapping populations, F and K8. Assessing the potential of mapping population progeny to segregate for drought traits of interest is an important aim of the study as it offers a potential route to the development of markers for drought tolerance trait selections within the Rothamsted Research willow breeding programme.Phenotypic and final harvest yield measurements were taken on all plants. Primary results reveal; that pot experiments were effective in producing a useful response to drought stress, that genotypic diversity for drought tolerance exists in Salix, an early drought coinciding with the exponential growth phase has a more negative effect on yield than a drought that occurs later in the growing season, and that top and middle leaf lengths may potentially offer the breeder a high throughput method of assessing the impact of drought on germplas

Trapped Ion Imaging with a High Numerical Aperture Spherical Mirror

Efficient collection and analysis of trapped ion qubit fluorescence is essential for robust qubit state detection in trapped ion quantum computing schemes. We discuss simple techniques of improving photon collection efficiency using high numerical aperture (N.A.) reflective optics. To test these techniques we placed a spherical mirror with an effective N.A. of about 0.9 inside a vacuum chamber in the vicinity of a linear Paul trap. We demonstrate stable and reliable trapping of single barium ions, in excellent agreement with our simulations of the electric field in this setup. While a large N.A. spherical mirror introduces significant spherical aberration, the ion image quality can be greatly improved by a specially designed aspheric corrector lens located outside the vacuum system. Our simulations show that the spherical mirror/corrector design is an easy and cost-effective way to achieve high photon collection rates when compared to a more sophisticated parabolic mirror setup.Comment: 5 figure

Species and Genotype Effects of Bioenergy Crops on Root Production, Carbon and Nitrogen in Temperate Agricultural Soil

Bioenergy crops have a secondary benefit if they increase soil organic C (SOC) stocks through capture and allocation below-ground. The effects of four genotypes of short-rotation coppice willow (Salix spp., ‘Terra Nova’ and ‘Tora’) and Miscanthus (M. × giganteus (‘Giganteus’) and M. sinensis (‘Sinensis’)) on roots, SOC and total nitrogen (TN) were quantified to test whether below-ground biomass controls SOC and TN dynamics. Soil cores were collected under (‘plant’) and between plants (‘gap’) in a field experiment on a temperate agricultural silty clay loam after 4- and 6-years’ management. Root density was greater under Miscanthus for plant (up to 15.5 kg m–3) compared with gap (up to 2.7 kg m–3) whereas willow had lower densities (up to 3.7 kg m–3). Over two years, SOC increased below 0.2 m depth from 7.1 to 8.5 kg m–3 and was greatest under Sinensis at 0-0.1 m depth (24.8 kg m–3). Miscanthus-derived SOC, based on stable isotope analysis, was greater under plant (11.6 kg m–3) than gap (3.1 kg m–3) for Sinensis. Estimated SOC stock change rates over the two-year period to 1-m depth were 6.4 for Terra Nova, 7.4 for Tora, 3.1 for Giganteus and 8.8 Mg ha–1 year–1 for Sinensis. Rates of change of TN were much less. That SOC matched root mass down the profile, particularly under Miscanthus, indicated that perennial root systems are an important contributor. Willow and Miscanthus offer both biomass production and C sequestration when planted in arable soil

On the application of radio frequency voltages to ion traps via helical resonators

Ions confined using a Paul trap require a stable, high voltage and low noise radio frequency (RF) potential. We present a guide for the design and construction of a helical coil resonator for a desired frequency that maximises the quality factor for a set of experimental constraints. We provide an in-depth analysis of the system formed from a shielded helical coil and an ion trap by treating the system as a lumped element model. This allows us to predict the resonant frequency and quality factor in terms of the physical parameters of the resonator and the properties of the ion trap. We also compare theoretical predictions with experimental data for different resonators, and predict the voltage applied to the ion trap as a function of the Q-factor, input power and the properties of the resonant circuit

Phenylalkanoid glycosides (non-salicinoids) from wood chips of Salix triandra × dasyclados hybrid willow

Salix triandra (almond leaved willow) is an established crop, grown in coppicing regimes for basket-making materials. It is known as a source of non-salicinoid phenolic glycosides such as triandrin and salidroside. A spontaneous natural hybrid of S. triandra and S. dasyclados was subjected to metabolite profiling by high resolution LC-MS and 22 phenolic glycosides, including 18 that are new to the Salicaceae were identified. Structures were determined by HPLC isolation and NMR methods. The hybridisation process has introduced novel chemistry into the Salix phenolic glycoside palette, in particular the ability to generate disaccharide conjugates where the glycosyl group is further extended by a range of sugars including apiose, rhamnose, xylose and arabinose. Also of note is the appearance of chavicol derivatives, also not previously seen in Salix spp. The work demonstrates the plasticity of the phenolic glycoside biosynthetic pathway and the potential to improve established crops such as S. triandra and S. dasyclados, via high-value metabolites, for both basketry and bioenergy markets

Genetic improvement of willow for bioenergy and biofuels

Willows (Salix spp.) are a very diverse group of catkin‐bearing trees and shrubs that are widely distributed across temperate regions of the globe. Some species respond well to being grown in short rotation coppice (SRC) cycles, which are much shorter than conventional forestry. Coppicing reinvigorates growth and the biomass rapidly accumulated can be used as a source of renewable carbon for bioenergy and biofuels. As SRC willows re‐distribute nutrients during the perennial cycle they require only minimal nitrogen fertilizer for growth. This results in fuel chains with potentially high greenhouse gas reductions. To exploit their potential for renewable energy, willows need to be kept free of pests and diseases and yields need to be improved without significantly increasing the requirements for fertilizers and water. The biomass composition needs to be optimized for different end‐uses. Yields also need to be sustainable on land less productive for food crops to reduce conflicts over land use. Advances in understanding the physiology and growth of willow, and in the identification of genes underlying key traits, are now at the stage where they can start to be used in breeding programs to help achieve these goals