Growth Chemistry Research Articles

Changes in the Soil–Plant–Water System Due to Biochar Amendment

The aim of this study was to do a complex examination of the soil–plant–water system and soil greenhouse gas emissions when biochar is applied to soil planted with sweet corn (Zea mays L. var. saccharata). The study covers two consecutive vegetation periods. We investigated (i) the changes in plant growth, (ii) soil water and temperature at different depths, (iii) greenhouse gas (GHG) emissions (CO2 and N2O) after biochar application, and (iv) the soil water, chemistry, and plant interactions. We used discrete measurements for plant growth, biomass production, and soil chemistry, while continuously monitoring the soil water content and temperature, and the state of plant health (i.e., using spectral reflectance sensors). Plant response in the control plot showed higher values of normalized difference vegetation index (NDVI; 0.3%) and lower values for photochemical reflectance index (PRI) and fraction of absorbed photosynthetically active radiation (fAPAR) by 26.8% and 2.24%, respectively, than for biochar treatments. We found significant negative correlations between fAPAR and soil water contents (SWC), and NDVI and SWC values (−0.59 < r < −0.30; p < 0.05). Soil temperature at the depth of 15 cm influenced soil CO2 emissions to a larger extent (r > 0.5; p < 0.01) than air temperature (0.21 < r < 0.33) or soil water content (r < 0.06; p > 0.05). Our data showed strong connections between GHG production and soil chemical parameters of soil pH, nitrogen, potassium, or phosphate concentrations. Biochar application increased soil CO2 emissions but reduced N2O emissions. Our results demonstrated that biochar amendment to soils can help plant growth initially, but might not result in enhanced crop yield. The plant parameters were substantially different between the investigated years for both control and biochar amended parcels; therefore, long-term studies are essential to document the lasting effects of these treatments.

Effects of [formula omitted]-[formula omitted] hydrocarbon blending on aromatics formation in 1-butene counterflow flames

We present a combined experimental and numerical analysis to provide insights into the chemical mechanisms that are responsible for the formation of one- and two-ring aromatic species under non-premixed conditions. To this end, sampling experiments in a 1-butene counterflow flame were conducted via time-of-flight molecular beam mass-spectrometry. The experimental dataset, which consists of 26mole fraction profiles of C1 to C12 hydrocarbons, was used to trace the formation of aromatic structures starting from the early-fuel decomposition stages. In additional experiments, the underlying fuel-dependent molecular-weight growth chemistry was identified by enhancing specific radical-radical and radical-molecule reactions via the partial substitution of 1-butene with methane, acetylene, and propene. Support for the interpretation of the experimental results was provided by the analysis of the formation pathways of aromatic species predicted by two established chemical mechanisms. By critically combining the information obtained from the measured relative changes in species concentrations and numerical simulations, the relevance of different reaction pathways was determined. Together with propargyl, the allyl radical was found to play a significant role in benzene formation and a direct dependence of toluene, ethylbenzene, and styrene on the benzene amount was observed. The less-studied propargyl addition to benzyl radicals was found to be the main contribution to naphthalene production under the investigated conditions. While species such as phenylacetylene (C8H6) and the −C2H substituted naphthalene (C12H8) showed an expected increase upon the addition of acetylene, also indene formation exhibits a dependence on acetylene chemistry. Formation pathways involving sequences of acetylene and methyl addition to aromatic radicals were identified as the responsible reactions for these trends.While the influence of the specific fuel chemistry on the formation of the second aromatic ring is confirmed by the analysis of these new measurements, the final inclusion of additional datasets acquired in previous works provides indications that such a dependence might progressively decay for three- and four-ring aromatics.

Influence of Mn and TiB<sub>2</sub> on the Microstructural Evolution of the Primary α-Al Grains and Fe Containing Intermetallic in the Wrought Al-Mg-Si Alloy

The most popular aluminium alloy used for the automotive applications is the wrought-Al alloy, where its popularity arises from its intrinsic characteristics such as, excellent formability, crash resistance, corrosion resistance and excellent specific strength. In the coming decades the use of aluminium alloys is expected to increase within automotive and aerospace industries, where this will source for an upsurge in Al recycling. Problems arise during Al recycling, where there is a steady build-up of Fe content, as this is recognised as being an impurity element. Fe has very little solubility in Al in its solid state and precipitation of these Fe intermetallics (IMC), in the Al matrix decrease mechanical properties, due to the Fe IMC brittle nature. These Fe-rich IMC also have very little cohesion to the Al matrix and can separate from the Al matrix resulting in the development of voids, where the initiation of microcracks becomes ostensible when subjected to thermomechanical processing. In order to curtail the damaging effect of the Fe IMC it so of importance to alter the nucleation and growth characteristic of the Fe rich IMC during solidification. Addition of trace elements and the manipulation of cooling rates have shown to be an effective technique to alter the Fe IMC morphology. In order observe the morphological evolution of the Fe IMC, various experiments were conducted using Al-1Si-1Mg-1Fe alloy with the addition of Mn and TiB2-based commercial grain refiner. Microstructural analysis of the primary α-Al and Fe IMC are observed and the morphological evolution of the Fe IMC is analysed with respects to the addition of Mn and TiB2. How the addition of these trace elements influence the growth characteristics and chemistry of the Al melt is also presented in this work.

Insights into the chemistry of aerosol growth in Beijing: Implication of fine particle episode formation during wintertime

Nucleation particle growth plays a major role in the occurrence of fine particles, yet the mechanism of new particle formation (NPF) remains ambiguous in the complex atmosphere of megacities and hinders the development of measures to mitigate PM2.5 pollution. In this study, the chemistry of ultrafine particles during the growth phase of nucleation events was investigated in urban Beijing from Nov. 15, 2018 to Jan. 15, 2019, using two scanning mobility particle spectrometers (SMPS) systems and an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). During this intense campaign, 11 NPF events were observed and the growth rate (GR) of nanoparticles ranged from 12.5 to 24.5 nm h−1. Four periodic cycles of PM2.5 episodes that included aerosol particle growth to particulate matter pollution were identified. Based on the QGR – QAMS theoretical frame that exploring the balance between the source rate of condensable vapors and the observed growth rate of nanoparticles, we clearly showed the physical and chemical evolution of nano-particle during the growth processes to ambient-atmosphere sizes (>100 nm). Generally, the modal diameter of aerosol particles grew by more than 100 nm (7 out of 11 NPF events) when the nitrate concentration and less-oxidized oxygenated organic aerosol (LO-OOA) were high; however, another class of aerosol particle growth was limited to 50–100 nm (3 out of 11 NPF events) when sulfate was high. Note that the remaining one NPF event could not be identified if it can grow up to 100 nm or not due to the unavailable of observation data during the late growth stage. By linking the aerosol growth with chemical compositions, sulfate and organics were found to be the main contributors during the initial stage of the aerosol growth, while cooking-related OA (COA) enhanced the transition stage, and nitrate and more-oxidized OOA (MO-OOA) dominated the subsequent growth of aerosol to ambient-atmosphere sizes. An important portion of aerosol growth in PM2.5 was controlled by semi-volatile organic vapors, which can partition into the externally condensed phase of the accumulation mode and coarse mode via the physical process of adsorption. Through quantifying the physical and chemical properties of aerosol particle growth, the detail processes of nucleation initiated PM2.5 pollution episodes were evaluated and provided observational evidence on the formation mechanism of winter haze pollution in the megacity of Beijing.

Influence of Satiation Feeding on the Water Quality and the Growth, Hematological Parameters, and Blood Chemistry of Nile Tilapia Oreochromis niloticus Reared in Nutrient Film Technique Aquaponic System

One of the most significant inputs in an aquaponic system is fish feed. Here, two satiation feeding (SF) levels (60% & 50%) have been tested. It aims to determine its effect on the water quality and the growth, hematological indices, and blood chemistry of Nile tilapia Oreochromis niloticus reared in nutrient film technique aquaponic system (NFTAS) containing upland kangkong Ipomea reptans within 1 month period and compared it in the recirculating system (RS). Results showed that the SF levels have an insignificant effect on the water quality between the systems mainly due to the nonoptimal pH level that influenced the nitrification efficiency and the inefficient uptake of nutrients by the plants in NFTAS. Consequently, the growth, hematological parameters, and blood chemistry of the fish reared in NFTAS have not improved compared with those in RS. However, the fish and the plant growth performance were better at 60% SF in both systems. Thus, 60% is suggested SF level when 200 individuals Nile tilapia O. niloticus tilapia fingerling (2.46 g, average initial weight) are reared within 31 days in a healthy and balanced NFTAS with 50 individuals upland kangkong I. reptans.

Canopy Nitrogen Addition and Soil Warming Affect Conifer Seedlings’ Phenology but Have Limited Impact on Growth and Soil N Mineralization in Boreal Forests of Eastern Canada

Changes in atmospheric N deposition and the global warming associated with human activities may impact soil organic matter mineralization rate, with possible consequences on ecosystem functioning and productivity. In this study, soil temperature was increased by +2–4 °C from April to July with heating cables and artificial rain was applied above the canopy of mature stands from June to September to simulate a 50% increase in N concentration of atmospheric deposition for a period of nine years (2008–2016) in two eastern Canada boreal forests (BER and SIM). We assessed the effects of these treatments on the rate of organic N mineralization and on the growth, phenology and N sources of Abies balsamea (L.) Mill. (balsam fir; BF) and Picea mariana (Mill.) BSP (black spruce; BS) seedlings growing below the mature tree’s canopies. The soil warming (SW) treatment had no significant effect on both net and gross N mineralization rates, whereas canopy N addition (CNA) decreased gross N mineralization rate by 23% and forest floor’s alkyl/O-alkyl C ratio by ~15% as compared to unfertilized plots. This decrease likely resulted from a reduced mining activity by soil microorganisms due to increased inorganic N availability. Foliar δ15N in the control plots was markedly lower in BS than in BF and at BER than at SIM (–4.8‰ and –2.9‰ in BS at BER and SIM, respectively; 1.6‰ and 3.8‰ in BF at BER and SIM, respectively). This was interpreted as a higher contribution of 15N-depleted N derived from mycorrhizal fungi in BS and at BER, the colder and the more N-depleted site. The SW and CNA treatments had nonsignificant effects on seedling growth and foliar chemistry. In contrast, SW caused a premature bud outbreak and faster bud development for both species at both sites. Overall, our results show that increased soil temperature and N deposition in boreal forests may not impact soil fertility and vegetation growth as much as previously thought, but climate warming, by initiating earlier and faster bud development, may however expose seedlings to late spring frosts in the future.

An arbuscular mycorrhizal fungus alters switchgrass growth, root architecture, and cell wall chemistry across a soil moisture gradient.

The abiotic environment can dictate the relative costs and benefits of plant-arbuscular mycorrhizal fungi (AMF) symbioses. While the effects of varying light or soil nutrient conditions are well studied, outcomes of plant-AMF interactions along soil moisture gradients are not fully understood. It is predicted that mycorrhizal associations may become parasitic in extreme soil moisture conditions. Under low soil moisture stress, costs of maintaining a mycorrhizal symbiont may outweigh benefits for the host plant, whereas under high soil moisture stress, the host plant may not need the symbiont. In a factorial growth chamber study, we investigated the effects of a plant-arbuscular mycorrhizal fungus symbiosis along a soil moisture gradient on growth, cell wall chemistry, and root architecture of a biofuel crop, Panicum virgatum (switchgrass). Regardless of soil moisture conditions, we found an increase in the number of tillers, number of leaves, root biomass, and amount of cellulose and hemicellulose in response to root colonization by the arbuscular mycorrhizal fungus. The fungus also increased aboveground biomass and changed several root architectural traits, but only under low soil moisture conditions, indicating a reduction in benefits of the mycorrhizal association under high soil moisture. Results from this study indicate that an arbuscular mycorrhizal fungus can increase some key measures of plant growth and cell wall chemistry regardless of soil moisture conditions but is most beneficial in low soil moisture conditions.

Effect of Folic Acid Supplementation and Dietary Protein Level on Growth Performance, Serum Chemistry and Immune Response in Weanling Piglets Fed Differing Concentrations of Aflatoxin.

Effects of folic acid and protein levels on growth and serum chemistry in pigs fed aflatoxin were determined in two experiments. Increasing aflatoxin (250 to 800 ppb) decreased (P < 0.05) weight gain and feed intake for both of the 35-day trials. In Experiment 1, increasing aflatoxin (0, 250, 500 ppb), increased linearly (P < 0.05) aspartate aminotransferase (AST), alkaline phosphatase (ALKP) and ɣ-glutamyl transferase (GGT). Folic acid (0, 2.0, 5.0, 12.5 ppm) increased linearly (P < 0.05) serum K, Ca, P, Mg, and AST with the largest effect observed at 12.5 ppm. Folic acid decreased (P < 0.05) blood urea nitrogen (BUN): creatinine and Na:K. In Experiment 2, aflatoxin (800 ppb) increased (P < 0.05) glucose and GGT, and decreased (P < 0.05) Na:K and albumin:globulin. Increasing protein from 15 to 18% elevated BUN: creatinine (P < 0.05), albumin: globulin (P < 0.05), albumin (P < 0.05) and ALKP (P < 0.05). Folic acid (2 ppm) elevated (P < 0.05) BUN, and interacted with both aflatoxin (P < 0.10) and protein (P < 0.05) on BUN. Adding folic acid to aflatoxin contaminated diets improved some measures of clinical chemistry in Experiment 1 but not traditional growth performance measures. The higher protein level reduced the effects of aflatoxicosis on growth.

El Niño – Southern Oscillation drives variations in growth and otolith chemistry in a top predatory fish

Sclerochronological approaches using fish otoliths provide a powerful and cost-effective means to evaluate fish responses to environmental variations in regions where there is a paucity of long-term data. We hypothesised that the dynamism in the environmental conditions associated with El Niño Southern Oscillation (ENSO) events in the Southern Atlantic Ocean would likely influence growth patterns and chemical records in fish otoliths. Hence, we developed a 46-year otolith increment-based growth chronology, and otolith chemical chronologies of Sr:Ca and Ba:Ca for an iconic top predatory fish, the dusky grouper Epinephelus marginatus collected off the southern coast of Brazil. Using a set of increasingly complex mixed-effects linear models, our biochronological approach revealed the influence of intrinsic and large-scale environmental drivers on growth and otolith chemical composition of dusky grouper. In particular, the intensity of the Multivariate ENSO index (a measure of the status of ENSO and El Niño or La Niña conditions) was negatively associated with growth, with rapid drops in average growth evident in very strong El Niño events (1992–93, 1997–98, or 2015–16). Similar negative relationships between ENSO and Ba:Ca composition reflected variations in environmental histories of dusky groupers, a species that is mostly sedentary in coastal reefs, whilst no environmental effects were detected for Sr:Ca. Overall, identifying the drivers that underlie variations in fish growth is a crucial challenge for any conservation or fisheries interest species as population dynamics, persistence and sustainable harvesting are tightly linked to individual growth. The development of chemical chronologies provided insight towards relating otolith elemental variation to environmental conditions at multidecadal scales, encouraging further evaluations of individual and population-level fluctuations of otolith chemistry and environmental reconstructions.

Effects of Dietary Xanthophyll Supplementation on Growth Performance, Body Color, Carotenoids, and Blood Chemistry Indices of Chinese Soft‐Shelled Turtle Pelodiscus sinensis

AbstractA 12‐week experiment was conducted to investigate the effects of diets containing 0 (CD), 40 (X1), 80 (X2), and 120 mg/kg (X3) xanthophyll on the growth, body color, and blood chemistry of the Chinese soft‐shelled turtle Pelodiscus sinensis. Four hundred and eighty turtles with initial weight of 37.90 ± 0.26 g were randomly stocked equally in 12 cement ponds (4.0 × 5.0 × 0.8 m) to form four groups in triplicate. The turtles were fed one of the four diets (crude protein 48%, crude lipid 6%) twice daily, with the feed amount set at 3% of their total body weight. The results indicated that the supplement of 80 mg/kg xanthophyll in the diet had the most significant effect on growth, feed conversion ratio, and amino acid content in muscle tissue. The yellowness of the carapace and the plastron skin increased with higher xanthophyll levels. Moreover, the final yellowness in the plastron skin was higher than the initial yellowness. The carotenoid content in the liver and carapace was significantly enhanced with increasing xanthophyll levels and showed a significant linear correlation with the dietary xanthophyll supplement levels. The liver carotenoid content in the X2 and X3 groups and carapace skin carotenoid content in the X3 group were markedly higher than were those in turtles that were fed the control diet (P &lt; 0.05). Compared with the control diet, adding xanthophyll significantly increased acid phosphatase activity in serum while obviously lowering the alanine aminotransferase activity. The triglyceride and total cholesterol content decreased with increases in xanthophyll. There were no significant differences in the serum superoxide dismutase and glutathione peroxidase activity in animals that received the xanthophyll‐supplemented and control diets. The current study results suggest that the growth performance and skin coloration of Chinese soft‐shelled turtle can be improved by including 80–120 mg/kg xanthophyll in the diet.

Facilitation of a tropical seagrass by a chemosymbiotic bivalve increases with environmental stress

Abstract Facilitation of foundation species is critical to the structure, function and persistence of ecosystems. Understanding the dependence of the strength of this facilitation on environmental conditions is important for informed ecosystem management and for predicting the impacts of global change. In coastal seagrass habitats, chemosymbiotic lucinid bivalves can facilitate seagrasses by decreasing potentially toxic levels of sulphide in sediment porewater. However, variation in the strength of lucinid–seagrass facilitation with environmental context has not been experimentally investigated. We tested the hypothesis that the presence of the tiger lucine Codakia orbicularis becomes more important to the growth and survival of the seagrass Thalassia testudinum under decreased light availability and increased sulphide stress. In a mesocosm experiment, we reduced average ambient‐light to T. testudinum by 64% and/or increased sediment porewater sulphide concentrations by ~200% and compared growth and tissue chemistry of T. testudinum with and without C. orbicularis. We found that T. testudinum was better able to maintain growth under shading and sulphide stress when C. orbicularis was present. C. orbicularis strongly decreased sediment porewater sulphide, an effect that minimized sulphur build‐up in seagrass tissue and was likely achieved through bioirrigation as well as chemoautotrophy. The relative effects of C. orbicularis on T. testudinum growth were strongest in the presence of environmental stressors. Synthesis. The strength of lucinid–seagrass facilitation increases under environmental conditions that hinder the ability of seagrass to detoxify sulphide. Our results provide evidence of a potential mechanism by which the spatiotemporal association between lucinids and seagrasses is maintained and support the incorporation of interspecific facilitation into conservation and restoration strategies for foundation species in the face of increasing anthropogenic impact and global change.

Root morphology and exudate availability are shaped by particle size and chemistry in Brachypodium distachyon.

Root morphology and exudation define a plants’ sphere of influence in soils. In turn, soil characteristics influence plant growth, morphology, root microbiome, and rhizosphere chemistry. Collectively, all these parameters have significant implications on the major biogeochemical cycles, crop yield, and ecosystem health. However, how plants are shaped by the physiochemistry of soil particles is still not well understood. We explored how particle size and chemistry of growth substrates affect root morphology and exudation of a model grass. We grew Brachypodium distachyon in glass beads with various sizes (0.5, 1, 2, 3 mm), as well as in sand (0.005, 0.25, 4 mm) and in clay (4 mm) particles and in particle‐free hydroponic medium. Plant morphology, root weight, and shoot weight were measured. We found that particle size significantly influenced root fresh weight and root length, whereas root number and shoot weight remained constant. Next, plant exudation profiles were analyzed with mass spectrometry imaging and liquid chromatography–mass spectrometry. Mass spectrometry imaging suggested that both, root length and number shape root exudation. Exudate profiles were comparable for plants growing in glass beads or sand with various particles sizes, but distinct for plants growing in clay for in situ exudate collection. Clay particles were found to sorb 20% of compounds exuded by clay‐grown plants, and 70% of compounds from a defined exudate medium. The sorbed compounds belonged to a range of chemical classes, among them nucleosides, organic acids, sugars, and amino acids. Some of the sorbed compounds could be desorbed by a rhizobacterium (Pseudomonas fluorescens WCS415), supporting its growth. This study demonstrates the effect of different characteristics of particles on root morphology, plant exudation and availability of nutrients to microorganisms. These findings further support the critical importance of the physiochemical properties of soils when investigating plant morphology, plant chemistry, and plant–microbe interactions.

Hypotensive Activity of Transgenic Rice Seed Accumulating Multiple Antihypertensive Peptides.

Peptides derived from food protein have the potential to become antihypertensive agents with relatively few negative side effects. Herein, multiple antihypertensive peptides, extracted from the transgenic rice seed, were administered intragastrically into spontaneously hypertensive rats (SHRs) with different dosages, resulting in a significant decrease in the systolic blood pressure (SBP). Furthermore, for a period of 5 weeks, daily intragastric administration of the transgenic rice flour also significantly reduced the SBP of SHRs but not the Wistar Kyoto normotensive rats (WNRs), most importantly, which did not affect the growth, development, or serum chemistry of SHRs or WNRs and did not cause any pathological changes. Our work provides an alternative source of natural antihypertensive agents.

Vibrational Spectroscopy as a Sensitive Probe for the Chemistry of Intra-Phase Bacterial Growth.

Bacterial growth in batch cultures occurs in four phases (lag, exponential/log, stationary and death phase) that differ distinctly in number of different bacteria, biochemistry and physiology. Knowledge regarding the growth phase and its kinetics is essential for bacterial research, especially in taxonomic identification and monitoring drug interactions. However, the conventional methods by which to assess microbial growth are based only on cell counting or optical density, without any insight into the biochemistry of cells or processes. Both Raman and Fourier transform infrared (FTIR) spectroscopy have shown potential to determine the chemical changes occurring between different bacterial growth phases. Here, we extend the application of spectroscopy and for the first time combine both Raman and FTIR microscopy in a multimodal approach to detect changes in the chemical compositions of bacteria within the same phase (intra-phase). We found a number of spectral markers associated with nucleic acids (IR: 964, 1082, 1215 cm−1; RS: 785, 1483 cm−1), carbohydrates (IR: 1035 cm−1; RS: 1047 cm−1) and proteins (1394 cm−1, amide II) reflecting not only inter-, but also intra-phase changes in bacterial chemistry. Principal component analysis performed simultaneously on FTIR and Raman spectra enabled a clear-cut, time-dependent discrimination between intra-lag phase bacteria probed every 30 min. This demonstrates the unique capability of multimodal vibrational spectroscopy to probe the chemistry of bacterial growth even at the intra-phase level, which is particularly important for the lag phase, where low bacterial numbers limit conventional analytical approaches.

The Effect of Dental Treatment under General Anesthesia on Quality of Life and Growth and Blood Chemistry Parameters in Uncooperative Pediatric Patients with Compromised Oral Health: A Pilot Study.

Background: The effect of untreated dental caries and their treatment under general anesthesia (GA) on the quality of life, growth, and blood chemistry parameters in uncooperative pediatric patients has not been extensively elucidated. The aims are to evaluate the impact of dental treatment under GA on oral health-related quality of life (OHRQoL) in uncooperative pediatric patients with severe dental caries and to assess the effect of dental treatment under GA on children’s weight (Wt), height (Ht), Body Mass Index (BMI), and blood chemistry parameters. Methods: Forty-three uncooperative children aged 3–14 years were selected. OHRQoL, through ECOHIS (Early Childhood Oral Health Impact Scale) and COHRQoL (Child Oral Health-Related Quality of Life) questionnaires, Wt, Ht, BMI, and blood chemistry parameters were measured at baseline and eight months after dental treatment under GA. Results: At follow up, the reductions in the ECHOIS and the COHRQoL components were statistically significant (p < 0.0001), there was significant improvement in the anthropometric measures: 76.5% of children increased the percentile curves for weight, 68.6% for height, and 51.4% for BMI; for the blood chemistry parameters: ferritin improved in 68.6% of the samples, PCR in 65.7%, ESR in 68.6%, Vitamin D in 68.6%, and IGF-1 in 65.7%. Conclusions: Oral health status significantly influences OHRQoL, growth, and blood chemistry parameters in uncooperative pediatric patients.

Response of aspen genotypes to browsing damage is not influenced by soil community diversity

Both environmental and genetic factors influence plant growth and foliar chemistry. The purpose of this experiment was to investigate the independent and interactive effects of soil community (and soil community diversity), tree genotype, and simulated browsing damage on the growth, biomass allocation and foliar chemistry of Populus tremuloides. We employed a factorial randomized complete block design with four soil treatments of varying diversity, five aspen genotypes, and a simulated ungulate browsing treatment. In the second year of growth, half the trees were subjected to simulated ungulate browsing, and 2 mo later trees were harvested and analyzed for biomass, biomass allocation, and foliar chemistry. Tree genotype was the strongest driver of foliar chemistry, but simulated browsing was the strongest driver of plant growth. Soil community influenced plant growth but not foliar chemistry, and soil community effects were rarely modified by tree genotype or simulated browsing. While environment and genotype had relatively equal influences on plant growth, tree genotype had a stronger influence than environmental effects (soil and simulated browsing) on foliar chemistry. We also documented negative plant–soil feedbacks for tree biomass. Our results highlight future opportunities for research on the potential effects of soil community diversity on trees.

Early growth phase and caffeine content response to recent and projected increases in atmospheric carbon dioxide in coffee (Coffea arabica and C. canephora)

While [CO2] effects on growth and secondary chemistry are well characterized for annual plant species, little is known about perennials. Among perennials, production of Coffea arabica and C. canephora (robusta) have enormous economic importance worldwide. Three Arabica cultivars (Bourbon, Catimor, Typica) and robusta coffee were grown from germination to ca. 12 months at four CO2 concentrations: 300, 400, 500 or 600 ppm. There were significant increases in all leaf area and biomass markers in response to [CO2] with significant [CO2] by taxa differences beginning at 122–124 days after sowing (DAS). At 366–368 DAS, CO2 by cultivar variation in growth and biomass response among Arabica cultivars was not significant; however, significant trends in leaf area, branch number and total above-ground biomass were observed between Arabica and robusta. For caffeine concentration, there were significant differences in [CO2] response between Arabica and robusta. A reduction in caffeine in coffee leaves and seeds might result in decreased ability against deterrence, and consequently, an increase in pest pressure. We suggest that the interspecific differences observed (robusta vs. Arabica) may be due to differences in ploidy level (2n = 22 vs. 2n = 4x = 44). Differential quantitative and qualitative responses during early growth and development of Arabica and robusta may have already occurred with recent [CO2] increases, and such differences may be exacerbated, with production and quality consequences, as [CO2] continues to increase.

Performance Enhancement by the Introduction of Additional Narrow Band Gap Bottom Layer of aSi0.64Ge0.36: H on Proposed p + aSi:H/i-aSi: H/n+ aSi0.73Ge0.27: H Thin Film Solar Cells

This work is the continuation of our previous work entitled "Investigations on optical, material and electrical properties of aSi:H and aSiGe:H in making proposed n+aSi:H/iaSi:H/p+aSiGe:H graded band gap solar cells." In this work, we present an additional bottom layer made of increased germanium content: aSi0.64Ge0.36:H to the previously recommended p+aSi:H/i-aSi:H/n+aSi0.73Ge0.27:H photovoltaic cell to strengthen the absorption spectrum and thereby boosting the attainment of the solar cell. Moreover, the overall active layer thickness is reduced from 430 nm of previous work to 395 nm of proposed work. This work includes the fabrication of samples of epitaxially grown aSiGe:H thin films of varying band gap made with Plasma Enhanced Chemical Vapour Deposition (PECVD) technique succeeded by their characterisation. The establishment of band gap tailoring by varying the germane (GeH4) gas flow rate is thoroughly investigated through optical characterisation. The growth chemistry of PECVD made aSi0.64Ge0.36:H layer has been analysed and the presence of respective radicals has been verified using Fourier Transform Infra Red (FTIR) spectroscopy. In accordance with the measured band gaps, p+ aSi:H/i-aSi:H/n+aSi0.73Ge0.27:H/naSi0.64Ge0.36:H solar cell has been proposed. A comprehensive inquiry on optimisation of the recommended structure has been made by varying the optical band gap and thickness of the bottom most aSi0.64Ge0.36:H layer of the structure. All the cell parameters including open circuit voltage (Voc), short circuit current density (Jsc), maximum power point voltage (Vm), maximum power point current density (Jm), Fill factor (FF) and conversion efficiency (η) has been calculated using SCAPS1D solar simulator. Furthermore, C–V characteristics and Mott-Schottky plot of the proposed structure has been evaluated. The introduction of narrow band gap amorphous silicon germanium (aSi0.64Ge0.36:H) at the bottom has remarkably enhanced Jsc and η to 15.54 mA/cm2 and 15.15% respectively, which is better compared to reported amorphous silicon photovoltaic cells having single junction.

Atomic Scale Design of Spinel ZnAl2O4 Nanocrystal Synthesis

The chemistry of ZnAl2O4 nanocrystal nucleation and growth is examined by X-ray scattering methods, and the results challenge the conventional understanding of its preparation by hydrothermal metho...

Aboveground resource allocation in response to root herbivory as affected by the arbuscular mycorrhizal symbiosis

Arbuscular mycorrhizal (AM) fungi associate with the majority of terrestrial plants, influencing their growth, nutrient uptake and defence chemistry. Consequently, AM fungi can significantly impact plant-herbivore interactions, yet surprisingly few studies have investigated how AM fungi affect plant responses to root herbivores. This study aimed to investigate how AM fungi affect plant tolerance mechanisms to belowground herbivory. We examined how AM fungi affect plant (Saccharum spp. hybrid) growth, nutrient dynamics and secondary chemistry (phenolics) in response to attack from a root-feeding insect (Dermolepida albohirtum). Root herbivory reduced root mass by almost 27%. In response, plants augmented investment in aboveground biomass by 25%, as well as increasing carbon concentrations. The AM fungi increased aboveground biomass, phosphorus and carbon. Meanwhile, root herbivory increased foliar phenolics by 31% in mycorrhizal plants, and increased arbuscular colonisation of roots by 75% overall. AM fungi also decreased herbivore performance, potentially via increasing root silicon concentrations. Our results suggest that AM fungi may be able to augment plant tolerance to root herbivory via resource allocation aboveground and, at the same time, enhance plant root resistance by increasing root silicon. The ability of AM fungi to facilitate resource allocation aboveground in this way may be a more widespread strategy for plants to cope with belowground herbivory.