Rothamsted Experimental Station Research Articles

EFFECT OF SUCROSE AND MEDIA STRENGTH ON IN VITRO MULTIPLICATION IN SWERTIA CHIRATA BUCH.-HAM EX WALL: AN ENDANGERED MEDICINAL HERB

Objective: The present study was performed to investigate the role of varying concentrations of carbohydrate source and strengths of nutrient medium in growth and development of in vitro shoots of Swertia chirata-an endangered medicinal plant.Methods: MS medium supplemented with 6-Benzylaminopurine (4.44 µM), Indole-3 acetic acid (2.85 µM) and Adenine sulphate (271.45 µM) was used to test the efficiency of of sucrose at concentrations of 1-5% and of media strength varying from full to one-fourth. The data were analysed using analysis of variance (ANOVA) of Completely Randomized Design (CRD) in GenStat 5 Edition 3.2 for PC/Windows NT (Copyright 1995, Lawes Agricultural Trust (Rothamsted Experimental Station))Results: Observations on axillary shoot multiplication indicated that sucrose at a concentration of 3% and MS medium in its full strength proved to be most optimal for in vitro culture multiplication. On this medium combination mean number of 11.80 shoots (after 4 w) and 18.50 shoots (after 8 w) could be obtained On sucrose free medium the shoots exhibited necrosis while at lower concentrations of 1-2% sucrose, the shoots developed were thin and unsuitable for further growth in vitro. At higher levels of sucrose in the medium, the shoots became thick and stunted. Similarly, reduction in medium strength resulted in a decline in shoot number and shoot length to an average of 6.50 shoots (1.33 cm mean length) on half strength medium and 5.60 shoots (0.88 cm mean length) on one-fourth strength; as observed after 4 w.Conclusion: The experimental findings suggest that any decline from the standard had a significant effect on the number, size and overall health of shoots developed in vitro. The conditions so standardized augment the production of healthy shoots that shall aid in subsequent rooting and survival after transplantation of tissue-culture raised plantlets.

Inorganic Nitrogen Application Affects Both Taxonomical and Predicted Functional Structure of Wheat Rhizosphere Bacterial Communities.

The effects of fertilizer regime on bulk soil microbial communities have been well studied, but this is not the case for the rhizosphere microbiome. The aim of this work was to assess the impact of fertilization regime on wheat rhizosphere microbiome assembly and 16S rRNA gene-predicted functions with soil from the long term Broadbalk experiment at Rothamsted Research. Soil from four N fertilization regimes (organic N, zero N, medium inorganic N and high inorganic N) was sown with seeds of Triticum aestivum cv. Cadenza. 16S rRNA gene amplicon sequencing was performed with the Illumina platform on bulk soil and rhizosphere samples of 4-week-old and flowering plants (10 weeks). Phylogenetic and 16S rRNA gene-predicted functional analyses were performed. Fertilization regime affected the structure and composition of wheat rhizosphere bacterial communities. Acidobacteria and Planctomycetes were significantly depleted in treatments receiving inorganic N, whereas the addition of high levels of inorganic N enriched members of the phylum Bacteroidetes, especially after 10 weeks. Bacterial richness and diversity decreased with inorganic nitrogen inputs and was highest after organic treatment (FYM). In general, high levels of inorganic nitrogen fertilizers negatively affect bacterial richness and diversity, leading to a less stable bacterial community structure over time, whereas, more stable bacterial communities are provided by organic amendments. 16S rRNA gene-predicted functional structure was more affected by growth stage than by fertilizer treatment, although, some functions related to energy metabolism and metabolism of terpenoids and polyketides were enriched in samples not receiving any inorganic N, whereas inorganic N addition enriched predicted functions related to metabolism of other amino acids and carbohydrates. Understanding the impact of different fertilizers on the structure and dynamics of the rhizosphere microbiome is an important step toward developing strategies for production of crops in a sustainable way.

The electronic Rothamsted Archive (e-RA), an online resource for data from the Rothamsted long-term experiments

The electronic Rothamsted Archive, e-RA (www.era.rothamsted.ac.uk) provides a permanent managed database to both securely store and disseminate data from Rothamsted Research’s long-term field experiments (since 1843) and meteorological stations (since 1853). Both historical and contemporary data are made available via this online database which provides the scientific community with access to a unique continuous record of agricultural experiments and weather measured since the mid-19th century. Qualitative information, such as treatment and management practices, plans and soil information, accompanies the data and are made available on the e-RA website. e-RA was released externally to the wider scientific community in 2013 and this paper describes its development, content, curation and the access process for data users. Case studies illustrate the diverse applications of the data, including its original intended purposes and recent unforeseen applications. Usage monitoring demonstrates the data are of increasing interest. Future developments, including adopting FAIR data principles, are proposed as the resource is increasingly recognised as a unique archive of data relevant to sustainable agriculture, agroecology and the environment.

The social wasp Vespula germanica (Fabricius) (Hymenoptera: Vespidae) population dynamics in England over 39 years.

1. Yearly records of worker Vespula germanica (Fabricius) taken in suction traps at Silwood Park (28 years) and at Rothamsted Research (39 years) are examined. 2. Using the autocorrelation function (ACF), a significant negative 1-year lag followed by a lesser non-significant positive 2-year lag was found in all, or parts of, each data set, indicating an underlying population dynamic of a 2-year cycle with a damped waveform. 3. The minimum number of years before the 2-year cycle with damped waveform was shown varied between 17 and 26, or was not found in some data sets. 4. Ecological factors delaying or preventing the occurrence of the 2-year cycle are considered.

Major limitations to achieving "4 per 1000" increases in soil organic carbon stock in temperate regions: Evidence from long-term experiments at Rothamsted Research, United Kingdom.

We evaluated the “4 per 1000” initiative for increasing soil organic carbon (SOC) by analysing rates of SOC increase in treatments in 16 long‐term experiments in southeast United Kingdom. The initiative sets a goal for SOC stock to increase by 4‰ per year in the 0–40 cm soil depth, continued over 20 years. Our experiments, on three soil types, provided 114 treatment comparisons over 7–157 years. Treatments included organic additions (incorporated by inversion ploughing), N fertilizers, introducing pasture leys into continuous arable systems, and converting arable land to woodland. In 65% of cases, SOC increases occurred at >7‰ per year in the 0–23 cm depth, approximately equivalent to 4‰ per year in the 0–40 cm depth. In the two longest running experiments (>150 years), annual farmyard manure (FYM) applications at 35 t fresh material per hectare (equivalent to approx. 3.2 t organic C/ha/year) gave SOC increases of 18‰ and 43‰ per year in the 23 cm depth during the first 20 years. Increases exceeding 7‰ per year continued for 40–60 years. In other experiments, with FYM applied at lower rates or not every year, there were increases of 3‰–8‰ per year over several decades. Other treatments gave increases between zero and 19‰ per year over various periods. We conclude that there are severe limitations to achieving the “4 per 1000” goal in practical agriculture over large areas. The reasons include (1) farmers not having the necessary resources (e.g. insufficient manure); (2) some, though not all, practices favouring SOC already widely adopted; (3) practices uneconomic for farmers—potentially overcome by changes in regulations or subsidies; (4) practices undesirable for global food security. We suggest it is more realistic to promote practices for increasing SOC based on improving soil quality and functioning as small increases can have disproportionately large beneficial impacts, though not necessarily translating into increased crop yield.

Pyrolysis temperature during biochar production alters its subsequent utilization by microorganisms in an acid arable soil

AbstractBiochar amendment of agricultural soils can have a significant impact on microbial carbon (C) metabolism by providing C substrates and altering soil properties, including amelioration of soil acidity. It remains unclear whether available C of biochar or its pH effects determines the utilization of biochar by microorganisms. Compound‐specific stable 13C isotope analysis of phospholipid fatty acids (13C‐phospholipid fatty acid analysis) was used to explore which microbial group utilized biochar distinguished with pHs and C availability. C4 Miscanthus biochar (δ13C = −12.2‰) was prepared at 2 pyrolysis temperatures (350 °C and 700 °C) and applied (50 mg C g−1 soil) to a very acid soil (pH 3.7, δ13C = −27.7‰), which was sampled from the long term Hoosfield Acid Strip experiment at Rothamsted Research, and incubated for 14 months. Biochar700 increased soil pH to 5.1 and biochar350 increased soil pH to 4.3. All microbial groups (Gram‐positive bacteria, Gram‐negative bacteria, actinobacteria, and fungi) were more abundant in the biochar‐treated soils. The 13C values of biomarker phospholipid fatty acid analysis suggested that all groups of microorganisms, and especially Gram‐positive bacteria, were using the C from the biochar350, but not the biochar700, as a substrate. We conclude that its utilization of biochar by microorganisms after 14 months was largely determined by the pyrolysis temperature controlling the availability of biochar C, instead of the pH effects, in a very acidic soil.

Interpopulation variability and adaptive potential for reduced glyphosate sensitivity in Alopecurus myosuroides.

SummaryGlyphosate use in the United Kingdom has more than doubled in the last 20 years. Much of this increase is driven by efforts to control herbicide resistant weeds, particularly Alopecurus myosuroides, prior to crop drilling. There is precedent for evolution of glyphosate resistance in similar situations, raising concerns over the sustainability of glyphosate use in the UK. We used dose–response experiments to examine variation in glyphosate sensitivity amongst 40 field‐collected A. myosuroides populations. No populations were resistant to glyphosate, but ED 90 values ranged between 354 and 610 g a.i. ha−1. Five populations had ED 90 values significantly higher than the unexposed control population collected from a site at Rothamsted Research with no previous glyphosate exposure. Recurrent selection experiments were performed to determine whether variation in glyphosate sensitivity had a heritable basis. Following two rounds of selection, five of six field populations evolved significantly reduced sensitivity to glyphosate, with R/S ratios, based on estimated ED 50 values, ranging from 1.2 to 1.5. These results confirm that there is a heritable basis to variation in glyphosate sensitivity. The response to selection was modest. Evolved populations were not highly resistant to glyphosate, although some twice‐selected individuals survived recommended field rates. These results do not represent definitive proof of the potential of A. myosuroides to evolve glyphosate resistance, although they do indicate caution is needed when considering the sustainability of increased glyphosate use to control this herbicide resistance‐prone species.

Effects of Cultivar and Nitrogen Nutrition on the Lipid Composition of Wheat Flour.

Despite being minor components of flour, wheat (Triticum aestivum L.) lipids contribute to grain processing. They are particularly important for bread making, where they adsorb to the surface of gas bubbles formed during the proving stage of bread making, stabilizing the gas cells and improving gas retention within the dough. This contributes to the volume and texture of the loaf. However, little is understood about how their amount, composition, and properties vary in response to genotype (G), environment (E) or G × E interactions. Six wheat lines were therefore grown at three levels of nitrogen supply at Rothamsted Research, and 48 lipid species across six lipid classes were identified and quantified in white flour using electrospray ionization-tandem triple quadrupole mass spectrometry (ESI-MS/MS). This showed clear differences in the contents and compositions of lipids between cultivar as well as effects of nitrogen fertilization, which would be expected to have impacts on the processing properties of the samples.

An evaluation of the hysteresis in chemical concentration–discharge (C–Q) relationships from drained, intensively managed grasslands in southwest England

ABSTRACTThis study examined the hysteresis exhibited in concentration–discharge (C–Q) relationships in the runoff from four hydrologically separated fields (catchments) at an intensively managed grassland. The objectives were to examine C–Q relationships constructed from high-resolution time series of flow, temperature, pH, conductivity, nitrate and turbidity, and their implications for hydrological processes. High-resolution datasets from the quality assured records of the Rothamsted Research North Wyke Farm Platform in the UK were examined using a graphical method and cross-correlation statistics. The study found that storm events based C–Q hysteresis reflects the cross-correlation that is generally hidden in time series analysis of large datasets, and that although Q and water quality variables can be effectively influenced by catchment size, the C–Q relationship is less significantly influenced. The dominant C–Q relationships of the water variables in the study area reflect that saturated overland flow was prevalent during the study period in the catchments, while the CCF results indicate coupled transfer of sediments and solute in the area at lag ≥ 0.EDITOR D. KoutsoyiannisASSOCIATE EDITOR M. D. Fidelibus

Historical trends in iodine and selenium in soil and herbage at the Park Grass Experiment, Rothamsted Research, UK

AbstractLong‐term trends in iodine and selenium retention in soil, and uptake by herbage, were investigated in archived samples from the Park Grass Experiment, initiated in 1856 at Rothamsted, UK. Soil (0–23 cm) and herbage samples from plots receiving various mineral fertilizers and organic manures, with and without lime, were analysed for selenium (Se) and iodine (I) to assess the effect of soil amendments, annual rainfall, crop yield and changes in soil chemistry from 1876 to 2008. Comparing soil from limed and unlimed control (unfertilized) plots, TMAH‐extractable Se and I concentrations both diverged, with time, with greater retention in unlimed plots; differences in concentration amounted to 92 and 1660 μg/kg for Se and I, respectively, after 105 yr. These differences were broadly consistent with estimated additions from rainfall and dry deposition. Offtake of both elements in herbage was negligible compared to soil concentrations and annual inputs (<0.003% of total soil I and <0.006% of total soil Se). A positive correlation was observed between I and Se concentrations in herbage, suggesting some common factors controlling bioavailability. A growth‐dilution effect for I and Se was suggested by the positive correlation between growing season rainfall (GSR) and herbage yield together with soil‐to‐plant transfer factors decreasing with yield. Phosphate and sulphate fertilizers reduced I and Se herbage concentrations, both through ion competition and increased herbage yield. Results suggest that in intensive agriculture with soil pH control, the I requirement of grazing animals is not likely to be met by herbage alone.

Molecular identification and distribution of leatherjackets (Diptera: Tipulidae) in U.K. agricultural grassland

Abstract DNA barcoding is useful for the identification of morphologically cryptic invertebrates. An important application is for pest species, for which it is critical to determine the distribution, biology and ecology of damaging life stages in order to target management effectively. Tipula paludosa (Meigen) and Tipula oleracea (Linnaeus) leatherjackets, the larvae of crane flies (Diptera: Tipulidae), are pests of agricultural grassland in Europe and the U.S.A. and are difficult to distinguish morphologically. We used cytochrome c oxidase subunit I (COI) barcoding to identify leatherjackets from 19 permanent grassland fields over 2 sampling seasons on the Rothamsted Research North Wyke Farm Platform, south west UK, to assess species-level distribution and genetic diversity. Most larvae (94%) were found to be T. paludosa, comprising 18 haplotypes that were spread across the sampling site in a panmictic population. However, T. oleracea were found in low abundance (3% of larval samples) and only in the second year of sampling. Other morphologically similar Dipteran larvae (3%) were also found. This dominance of one species suggests that there may be underlying differences in species biology, such as choice of oviposition site and dispersal ability, which is in agreement with other studies and has implications for monitoring and management.

Detection of biotic and abiotic stresses in crops by using hierarchical self organizing classifiers

Hyperspectral signatures can provide abundant information regarding health status of crops; however it is difficult to discriminate between biotic and abiotic stress. In this study, the case of simultaneous occurrence of yellow rust disease symptoms and nitrogen stress was investigated by using hyperspectral features from a ground based hyperspectral imaging system. Hyperspectral images of healthy and diseased plant canopies were taken at Rothamsted Research, UK by a Specim V10 spectrograph. Five wavebands of 20 nm width were utilized for accurate identification of each of the stress and healthy plant conditions. The technique that was developed used a hybrid classification scheme consisting of hierarchical self organizing classifiers. Three different architectures were considered: counter-propagation artificial neural networks, supervised Kohonen networks (SKNs) and XY-fusion. A total of 12 120 spectra were collected. From these 3 062 (25.3%) were used for testing. The results of biotic and abiotic stress identification appear to be promising, reaching more than 95% for all three architectures. The proposed approach aimed at sensor based detection of diseased and stressed plants so that can be treated site specifically contributing to a more effective and precise application of fertilizers and fungicides according to specific plant’s needs.

The value of long‐term data in agricultural systems

The value of long‐term data in agricultural systems

David Stewart Jenkinson. 25 February 1928 — 16 February 2011

David Jenkinson was one of the most influential soil scientists of his generation, bringing new insights into the transformations of organic matter and nitrogen in soil. He spent the majority of his career at Rothamsted Research, Harpenden, UK. His studies were influential regarding the role of soil carbon stocks in the context of climate change and the role of nitrogen fertilizer in delivering adequate supplies of food for a growing world population. His research encompassed both fundamental studies on soil processes and immensely practical applications of this knowledge, often utilizing the Rothamsted long-term experiments that have run for over 170 years. He is particularly well known for his development of a method for determining the quantity of organic carbon held in the cells of living micro-organisms in soil, termed the ‘soil microbial biomass’. This breakthrough opened the way for a new wave of soil biological research. David developed one of the earliest computer models for the turnover of organic carbon in soil, known as the Rothamsted Carbon Model, RothC. This model, conceptually very simple, has proved highly successful in simulating and predicting changes in soil organic carbon (SOC) content under different management practices worldwide, being used by over 2600 people in 115 countries. His research using the stable isotope of nitrogen, 15 N, in large-scale field experiments drew attention to the factors leading to inefficiencies in the use of nitrogen fertilizer but also demonstrated that it is possible to achieve high efficiency if good agricultural management practices are followed. It also demonstrated, more clearly than previously, the great importance of soil organic matter as a source of nitrogen for crops and the role of the soil microbial biomass both in immobilizing a proportion of applied fertilizer nitrogen and also in causing confusion in the interpretation of such experiments. By calculating nitrogen budgets for the Rothamsted long-term experiments he quantified the deposition of nitrogen compounds from atmosphere to land, laying foundations for later studies concerning the ecological and agricultural impacts of this significant input of nitrogen.

150 years of macronutrient change in unfertilized UK ecosystems: Observations vs simulations

Understanding changes in plant-soil C, N and P using data alone is difficult due to the linkages between carbon, nitrogen and phosphorus cycles (C, N and P), and multiple changing long-term drivers (e.g. climate, land-use, and atmospheric N deposition). Hence, dynamic models are a vital tool for disentangling these drivers, helping us understand the dominant processes and drivers and predict future change. However, it is essential that models are tested against data if their outputs are to be concluded upon with confidence. Here, a simulation of C, N and P cycles using the N14CP model was compared with time-series observations of C, N and P in soils and biomass from the Rothamsted Research long-term experiments spanning 150years, providing an unprecedented temporal integrated test of such a model. N14CP reproduced broad trends in soil organic matter (SOM) C, N and P, vegetation biomass and N and P leaching. Subsequently, the model was used to decouple the effects of land management and elevated nitrogen deposition in these experiments. Elevated N deposition over the last 150years is shown to have increased net primary productivity (NPP) 4.5-fold and total carbon sequestration 5-fold at the Geescroft Wilderness experiment, which was re-wilded to woodland in 1886. In contrast, the model predicts that for cropped grassland conditions at the Park Grass site, elevated N deposition has very little effect on SOM, as increases in NPP are diverted from the soil. More broadly, these results suggest that N deposition is likely to have had a large effect on SOM and NPP in northern temperate and boreal semi-natural grasslands and forests. However, in cropped and grazed systems in the same region, whilst NPP may have been supported in part by elevated N deposition, declines in SOM may not have been appreciably counteracted by increased N availability.

Local variation in hedonic house pricing in Hanoi, Vietnam: a spatial analysis of status quality trade-off (SQTO) theory

GIScience 2016 Short Paper Proceedings Local variation in hedonic house price, Hanoi: a spatial analysis of SQTO theory A. J. Comber 1 , P. Harris 2 , T. Q. Nguyen 3 , P. K. Chi 4 , H. Tran 4 and H. H. Phe 5 School of Geography, University of Leeds, LS2 9JT, UK Email: a.comber@leeds.ac.uk Rothamsted Research, North Wyke, Okehampton, EX20 2SB, UK Email: paul.harris@rothamsted.ac.uk National University of Civil Engineering, Hanoi, Vietnam Email: quannt@nuce.edu.vn GeoViet Consulting Co. Ltd, Hanoi, Vietnam Email: chi.geoviet@gmail.com Vinaconex RD Fujita, 1989). In these, access to place of work to minimise commuting costs, for example, is one of the main factors explaining residential location choices for lower- income households and higher-income households choose larger properties in the suburbs

Grassland biodiversity bounces back from long-term nitrogen addition.

The negative effect of increasing atmospheric nitrogen (N) pollution on grassland biodiversity is now incontrovertible. However, the recent introduction of cleaner technologies in the UK has led to reductions in the emissions of nitrogen oxides, with concomitant decreases in N deposition. The degree to which grassland biodiversity can be expected to 'bounce back' in response to these improvements in air quality is uncertain, with a suggestion that long-term chronic N addition may lead to an alternative low biodiversity state. Here we present evidence from the 160-year-old Park Grass Experiment at Rothamsted Research, UK, that shows a positive response of biodiversity to reducing N addition from either atmospheric pollution or fertilizers. The proportion of legumes, species richness and diversity increased across the experiment between 1991 and 2012 as both wet and dry N deposition declined. Plots that stopped receiving inorganic N fertilizer in 1989 recovered much of the diversity that had been lost, especially if limed. There was no evidence that chronic N addition has resulted in an alternative low biodiversity state on the Park Grass plots, except where there has been extreme acidification, although it is likely that the recovery of plant communities has been facilitated by the twice-yearly mowing and removal of biomass. This may also explain why a comparable response of plant communities to reduced N inputs has yet to be observed in the wider landscape.

Colin G Butler, MA, PhD, FRPS, FlBiol, OBE, FRS (1913–2016)

Dr. Colin Gasking Butler, former Head of the Bee Department at Rothamsted Experimental Station, UK, died peacefully on 4 January after a short illness, at the age of 102. He is credited as the disc...

IRCHLB-IV-Abstracts of Presentations at the 4th International Research Conference on Huanglongbing

IRCHLB-IV-Abstracts of Presentations at the 4th International Research Conference on Huanglongbing

Endophytic bacterial community composition in wheat (Triticum aestivum) is determined by plant tissue type, developmental stage and soil nutrient availability

To understand effects of tissue type, growth stage and soil fertilisers on bacterial endophyte communities of winter wheat (Triticum aestivum cv. Hereward). Endophytes were isolated from wheat grown under six fertiliser conditions in the long term Broadbalk Experiment at Rothamsted Research, UK. Samples were taken in May and July from root and leaf tissues. Root and leaf communities differed in abundance and composition of endophytes. Endophytes were most abundant in roots and the Proteobacteria were most prevalent. In contrast, Firmicutes and Actinobacteria, the Gram positive phyla, were most prevalent in the leaves. Both fertiliser treatment and sample time influenced abundance and relative proportions of each phylum and genus in the endosphere. A higher density of endophytes was found in the Nil input treatment plants. Robust isolation techniques and stringent controls are critical for accurate recovery of endophytes. The plant tissue type, plant growth stage, and soil fertiliser treatment all contribute to the composition of the endophytic bacterial community in wheat. These results should help facilitate targeted development of endophytes for beneficial applications in agriculture.