Reduced Plant Size Research Articles

Characterization of crystallized struvite on wastewater treatment equipment: Prospects for crystal fertilizer production

With over-mining of the natural rock-P, food production will plummet sooner than we envisage since they are essential in agro-industry but are non-renewable. Hence, phosphate fertilizers are going to be limited in future. Struvite is a crystalline mineral substance containing equimolar amount (1:1:1) of magnesium and ammonium phosphate(V) (MgNH PO O), a good source of phosphorus and a slow-release fertilizer. In this study, a sample of the4 struvite4· 6H2 formed in the wastewater treatment equipment of Kilang Kelapa Sawit, Sri Senggora (Palm Oil Mill at Pahang, Malaysia) was collected and characterized to determine its suitability for use as a slow-release fertilizer for agricultural purposes. The formation of struvite in the sewage pipes of wastewater treatment facility causes bottlenecks in the operation of the plant and results in reduced pumping efficiencies and high cost of overall plant maintenance. Due to the P, N and Mg content in the palm oil wastewater streams, struvite formation is triggered, and the treatment equipment are clogged as the struvite precipitates and builds up. The results of the characterization of the struvite through SEM-EDX, FTIR, XRD and TG-DTA/DSC analyses give the morphology and atomic percentage of the different elemental composition, the absorption pattern of the different functional groups, the orthorhombic crystal structure arrangement and the loss of mass against temperature respectively. The results indicate that high quality and large quantity struvite can be recovered from the palm oil wastewater streams. The recovery of struvite will reduce the BOD and COD of the wastewater stream resulting in plant size reduction, small land space requirements and reduced cost. This phenomenon being eco-recycling of phosphorus will serve as a sustainable approach towards food security and can help mitigate the problem of eutrophication.

Overexpression of the class I homeodomain transcription factor TaHDZipI-5 increases drought and frost tolerance in transgenic wheat.

SummaryCharacterization of the function of stress‐related genes helps to understand the mechanisms of plant responses to environmental conditions. The findings of this work defined the role of the wheat TaHDZipI‐5 gene, encoding a stress‐responsive homeodomain–leucine zipper class I (HD‐Zip I) transcription factor, during the development of plant tolerance to frost and drought. Strong induction of TaHDZipI‐5 expression by low temperatures, and the elevated TaHDZipI‐5 levels of expression in flowers and early developing grains in the absence of stress, suggests that TaHDZipI‐5 is involved in the regulation of frost tolerance at flowering. The TaHDZipI‐5 protein behaved as an activator in a yeast transactivation assay, and the TaHDZipI‐5 activation domain was localized to its C‐terminus. The TaHDZipI‐5 protein homo‐ and hetero‐dimerizes with related TaHDZipI‐3, and differences between DNA interactions in both dimers were specified at 3D molecular levels. The constitutive overexpression of TaHDZipI‐5 in bread wheat significantly enhanced frost and drought tolerance of transgenic wheat lines with the appearance of undesired phenotypic features, which included a reduced plant size and biomass, delayed flowering and a grain yield decrease. An attempt to improve the phenotype of transgenic wheat by the application of stress‐inducible promoters with contrasting properties did not lead to the elimination of undesired phenotype, apparently due to strict spatial requirements for TaHDZipI‐5 overexpression.

The contributions of biological control to reduced plant size and biomass of water hyacinth populations

Water hyacinth is invasive in many countries, where it reduces aquatic biodiversity and limits water resource utilisation. Biological control of water hyacinth has been successful in South Africa, but has suffered from a lack of empirical data to prove causation. Insect exclusion trials were conducted to quantify the contribution of Neochetina eichhorniae and N. bruchi to the integrated control of water hyacinth on the Nseleni River, South Africa. Insecticide was not expected to induce phytotoxicity, but would prevent weevil damage in water hyacinth plants; and weevil herbivory was predicted to reduce plant petiole length, and above/below surface biomass. Results showed that insecticide had no phytotoxic effects and excluded weevils for 3 weeks, providing a baseline for field applications. Biological control on the Nseleni River directly affected water hyacinth biomass and petiole length, but did not affect plant cover. Plants subject to weevil herbivory demonstrated reductions in above and below surface biomass and had shorter petioles compared to insect-free plants. Dead biomass was also higher in biological control treatments. Biological control strongly affects plant size, biomass and vigour; however, further integrated control is required to facilitate reduction in mat cover, which is the goalpost for successful control of floating aquatic plants.

Cellulose-Supported Ionic Liquids for Low-Cost Pressure Swing CO2 Capture

Reducing the cost of capturing CO2 from point source emitters is a major challenge facing Carbon Capture, Utilisation and Storage. While Solid Ionic Liquids (SoILs) have been shown to allow selective and rapid CO2 capture by pressure swing separation of flue gases, expectations of their high cost hinders their potential application. Cellulose is found to be a reliable, cheap and sustainable support for a range of SoILs, reducing the total sorbent cost by improving the efficiency of the ionic liquid through increased ionic surface area that results from coating. It was also found that cellulose support imparts surface characteristics, which increased total sorbent uptake. Combined, these effects allowed a 4 to 8-fold improvement in uptake per gram of ionic liquid for SoILs that have previously shown high uptake and a 9 to 39-fold improvement for those with previously poor uptake, offering the potential to drastically reduce the amount of ionic liquid required to separate a given gas volume. Furthermore, the fast kinetics are retained which means het rapid cycling can be achieved which results in high separation capacity relative to conventional temperature swing process. The projected reduction in plant size and operational costs represents a potentially ground-breaking step forward is carbon dioxide capture technologies.

Potassium Starvation Limits Soybean Growth More than the Photosynthetic Processes across CO2 Levels.

Elevated carbon dioxide (eCO2) often enhances plant photosynthesis, growth, and productivity. However, under nutrient-limited conditions the beneficial effects of high CO2 are often diminished. To evaluate the combined effects of potassium (K) deficiency and eCO2 on soybean photosynthesis, growth, biomass partitioning, and yields, plants were grown under controlled environment conditions with an adequate (control, 5.0 mM) and two deficient (0.50 and 0.02 mM) levels of K under ambient CO2 (aCO2; 400 μmol mol−1) and eCO2 (800 μmol mol−1). Results showed that K deficiency limited soybean growth traits more than photosynthetic processes. An ~54% reduction in leaf K concentration under 0.5 mM K vs. the control caused about 45% less leaf area, biomass, and yield without decreasing photosynthetic rate (Pnet). In fact, the steady photochemical quenching, efficiency, and quantum yield of photosystem II, chlorophyll concentration (TChl), and stomatal conductance under 0.5 mM K supported the stable Pnet. Biomass decline was primarily attributed to the reduced plant size and leaf area, and decreased pod numbers and seed yield in K-deficient plants. Under severe K deficiency (0.02 mM K), photosynthetic processes declined concomitantly with growth and productivity. Increased specific leaf weight, biomass partitioning to the leaves, decreased photochemical quenching and TChl, and smaller plant size to reduce the nutrient demands appeared to be the means by which plants adjusted to the severe K starvation. Increased K utilization efficiency indicated the ability of K-deficient plants to better utilize the tissue-available K for biomass accumulation, except under severe K starvation. The enhancement of soybean growth by eCO2 was dependent on the levels of K, leading to a K × CO2 interaction for traits such as leaf area, biomass, and yield. A lack of eCO2-mediated growth and photosynthesis stimulation under severe K deficiency underscored the importance of optimum K fertilization for maximum crop productivity under eCO2. Thus, eCO2 compensated, at least partially, for the reduced soybean growth and seed yield under 0.5 mM K supply, but severe K deficiency completely suppressed the eCO2-enhanced seed yield.

Transcriptome profiling of cucumber genome expression in response to long-term low nitrogen stress

The present study aimed to delineate the genes mediating nitrogen metabolism in cucumber (Cucumis sativus L.) and elucidate the mechanisms underlying the response to long-term nitrogen limitation. As an economically important crop, cucumber is strongly nitrogen dependent. The mechanisms underlying nitrogen metabolism in cucumber are not fully known. This study found that cucumber developed to a 3.5-leaf stage with reduced plant size and biomass under chronic low nitrogen stress condition. Gene expression profiling and analysis of cucumber roots and leaves under nitrogen-starved condition identified a total of 2991 unigenes as reliable differentially expressed genes (DEGs). A comprehensive analysis of the transcriptome revealed that the mechanisms underlying the response of cucumber roots to nitrogen-deficient stress were considerably different from those of its leaves. Importantly, the DEGs involved in the photosynthesis were almost downregulated, suggesting that the photosystem was sensitive to nitrogen starvation. Otherwise, the nitrate metabolic pathway of cucumber was suppressed by nitrogen deficiency, which was further confirmed by quantitative reverse transcription–polymerase chain reaction. This study represents a comparative analysis of the transcriptome levels of roots and leaves of cucumber, which possibly provides a valuable resource for further investigating the mechanism underlying plant response to long-term nitrogen limitation stress along with the candidate genes controlling the nitrogen metabolism.

Isolation and characterization of a floral homeotic gene in Fraxinus nigra causing earlier flowering and homeotic alterations in transgenic Arabidopsis

Reproductive sterility, which can be obtained by manipulating floral organ identity genes, is an important tool for gene containment of genetically engineered trees. In Arabidopsis, AGAMOUS (AG) is the only C-class gene responsible for both floral meristem determinacy and floral organ identity, and its mutations produce sterility. As a first step in an effort to develop transgenic sterile black ash (Fraxinus nigra), an AG ortholog in black ash (FnAG) was isolated using reverse transcription polymerase chain reaction and rapid amplification of cDNA ends. Analysis of the deduced amino acid sequence showed a typical MIKC structure of type II plant MADS-box protein with a highly conserved MADS-domain. Phylogenetic analysis revealed that FnAG had a close relationship with AG orthologs from other woody species. FnAG transcript was mainly expressed in reproductive tissues, but rarely detected in the vegetative tissues, consistent with the ABC model for floral development. A functional analysis was performed by ectopic expression of FnAG driven by the CaMV 35S promoter in transgenic Arabidopsis. Transformed plants showed homeotic conversions of carpeloid sepals and stamenoid petals. Curled leaves, reduced plant size, and earlier flowering were also observed in transgenic Arabidopsis. These data indicated that the FnAG functions in the same way as AG in Arabidopsis. These results provide the framework for targeted genome editing of black ash, an ecologically and economically important wetland species.

Pokeweed (Phytolacca americana L.) antiviral protein inhibits Zucchini yellow mosaic virus infection in a dose-dependent manner in squash plants

Pokeweed antiviral protein (PAP) of Phytolacca americana L. (pokeweed) is a single-chain ribosome-inactivating protein (RIP) characterized by its ability to depurinate plant ribosomes. Here, we isolated, cloned, and expressed the ribosome inactivating protein (RIP) gene, designated as pokeweed antiviral protein type 1 (PAP I), from the summer leaves of pokeweed collected from the Black Sea region (Turkey). Our findings presented here provide direct evidence that exogenous application of PAP I causes concentration-dependent inhibition of Zucchini yellow mosaic virus (ZYMV) infection on squash plants. Squash plants were exposed to PAP I protein with and without DMSO for four consecutive days. Regular spraying of approximately 30 kDa recombinant PAP I at 2 µg mL?1 concentration prevented treated plants from mechanical virus infection. PAP I showed antiviral activity in 9 plants out of 15 inoculated plants. Remarkably, simultaneous application of PAP, DMSO, and ZYMV did not prevent virus infection, suggesting that PAP did not have any effect on viral RNA. In the absence of ZYMV the purified peptide was not cytotoxic for squash plants, although a reduction of plant size, possibly caused by host ribosome depurination, was observed.

Impacts of Insect Herbivores on Plant Populations.

Apparent feeding damage by insects on plants is often slight. Thus, the influences of insect herbivores on plant populations are likely minor. The role of insects on host-plant populations can be elucidated via several methods: stage-structured life tables of plant populations manipulated by herbivore exclusion and seed-addition experiments, tests of the enemy release hypothesis, studies of the effects of accidentally and intentionally introduced insect herbivores, and observations of the impacts of insect species that show outbreak population dynamics. These approaches demonstrate that some, but not all, insect herbivores influence plant population densities. At times, insect-feeding damage kills plants, but more often, it reduces plant size, growth, and seed production. Plant populations for which seed germination is site limited will not respond at the population level to reduced seed production. Insect herbivores can influence rare plant species and need to be considered in conservation programs. Alterations due to climate change in the distributions of insect herbivores indicate the possibility of new influences on host plants. Long-term studies are required to show if density-related insect behavior stabilizes plant populations or if environmental variation drives most temporal fluctuations in plant densities. Finally, insects can influence plant populations and communities through changing the diversity of nonhost species, modifying nutrient fluxes, and rejuvenating over mature forests.

A Nitrogen-Fixing Subunit Essential for Accumulating 4Fe-4S-Containing Photosystem I Core Proteins.

Nitrogen-fixation-subunit-U (NFU)-type proteins have been shown to be involved in the biogenesis of iron-sulfur clusters. We investigated the molecular function of a chloroplastic NFU-type iron-sulfur scaffold protein, NFU3, in Arabidopsis (Arabidopsis thaliana) using genetics approaches. Loss-of-function mutations in the NFU3 gene caused yellow pigmentation in leaves, reductions in plant size, leaf size, and growth rate, delay in flowering and seeding, and decreases in seed production. Biochemical and physiological analyses indicated that these defects are due to the substantial reductions in the abundances of 4Fe-4S-containing photosystem I (PSI) core subunits PsaA (where Psa stands for PSI), PsaB, and PsaC and a nearly complete loss of PSI activity. In addition to the substantial decreases in the amounts of PSI core proteins, the content of 3Fe-4S-containing ferredoxin-dependent glutamine oxoglutarate aminotransferases declined significantly in the nfu3 mutants. Furthermore, the absorption spectrum of the recombinant NFU3 protein showed features characteristic of 4Fe-4S and 3Fe-4S clusters, and the in vitro reconstitution experiment indicated an iron-sulfur scaffold function of NFU3. These data demonstrate that NFU3 is involved in the assembly and transfer of 4Fe-4S and 3Fe-4S clusters and that NFU3 is required for the accumulation of 4Fe-4S- and 3Fe-4S-containing proteins, especially 4Fe-4S-containing PSI core subunits, in the Arabidopsis chloroplast.

High perennial ryegrass seeding rates reduce plant size and survival during the first year after sowing: does this have implications for pasture sward persistence?

AbstractFailure of perennial ryegrass swards to persist is a key issue on dairy farms in many areas of the world. This study describes an experiment conducted to test the hypothesis that high ryegrass seeding rates (>18 kg seed ha−1) reduce plant size and physical survival during the first year after sowing, with negative implications for population persistence. Four cultivars representing four functional types of perennial ryegrass were sown at five seeding rates (equivalent to 6, 12, 18, 24 and 30 kg seed ha−1) with white clover in three dairying regions of New Zealand. Plant establishment rates, size and survival were measured for the first 13 months after sowing. Herbage accumulation, botanical composition and perennial ryegrass tiller density were also monitored. Increasing seeding rate reduced plant survival in the seven weeks after sowing, reflecting likely differences in germination and very early mortality of small seedlings. Thereafter, plant survival was relatively high and consistent across seeding rates at two sites but was consistently greater in the 6 kg ha−1 treatment compared with the 24 and 30 kg ha−1 treatments at one site. Higher seeding rates also increased ryegrass tiller density and the contribution of ryegrass towards total herbage biomass but reduced the contribution of white clover. Very few cultivar × seeding rate interactions were detected for any of the measured variables. Many of the seeding rate effects dissipated by the end of the first year after sowing, indicating that high seeding rates did not predispose swards to poor persistence in the longer term, irrespective of ryegrass functional type.

Negative plant-soil feedbacks increase with plant abundance, and are unchanged by competition.

Plant-soil feedbacks and interspecific competition are ubiquitous interactions that strongly influence the performance of plants. Yet few studies have examined whether the strength of these interactions corresponds with the abundance of plant species in the field, or whether feedbacks and competition interact in ways that either ameliorate or exacerbate their effects in isolation. We sampled soil from two intermountain grassland communities where we also measured the relative abundance of plant species. In greenhouse experiments, we quantified the direction and magnitude of plant-soil feedbacks for 10 target species that spanned a range of abundances in the field. In soil from both sites, plant-soil feedbacks were mostly negative, with more abundant species suffering greater negative feedbacks than rare species. In contrast, the average response to competition for each species was unrelated with its abundance in the field. We also determined how competitive response varied among our target species when plants competed in live vs. sterile soil. Interspecific competition reduced plant size, but the strength of this negative effect was unchanged by plant-soil feedbacks. Finally, when plants competed interspecifically, we asked how conspecific-trained, heterospecific-trained, and sterile soil influenced the competitive responses of our target species and how this varied depending on whether target species were abundant or rare in the field. Here, we found that both abundant and rare species were not as harmed by competition when they grew in heterospecific-trained soil compared to when they grew in conspecific-cultured soil. Abundant species were also not as harmed by competition when growing in sterile vs. conspecific-trained soil, but this was not the case for rare species. Our results suggest that abundant plants accrue species-specific soil pathogens to a greater extent than rare species. Thus, negative feedbacks may be critical for preventing abundant species from becoming even more abundant than rare species.

Mutagenesis and Biotechnology Techniques as Tools for Selecting New Stable Diploid and Tetraploid Olive Genotypes and Their Dwarfing Agronomical Characterization

In Olea europaea L. subsp. europaea, tetraploid genotypes do not exist in nature. Herein, we report the first example of selection of tetraploid olive plants, obtained by combining physical mutagenesis and biotechnology techniques. Stable tetraploid (4n) and diploid (2n) genotypes were isolated in vitro through shoot-tip fragmentation of two mixoploid mutants derived from the gamma irradiation of self-incompatible Leccino and self-compatible Frantoio cultivars. In this study, the stable mutants FRM5-4n, FRM5-2n, LM3-4n, and LM3-2n were characterized in the field for vegetative and reproductive behavior with the aim to use them as varieties or dwarfing rootstocks. The stable 4n genotype of Leccino acquired self-fertility whereas the 4n Frantoio maintained it. A high and constant yield was showed by LM3-2n during 9 years of observation, maintaining the same oil quality as the Leccino wild type (wt). Moreover, the LM3-2n acquired the capacity to be intercompatible with the diploid mutant Leccino dwarf (LD) and with the Leccino wt. This acquired property would allow for a reduction of heterozygosity in the offspring, if crossed with each other for some generations and with the Leccino wt, because it is a sort of self-fertilization. When used as rootstocks, both 4n and 2n Leccino mutants proved to be very effective for reducing the scion size of the high-vigor Canino cultivar, which is well known for its excellent extravirgin oil. Finally, it was demonstrated that the self-grafting of vigorous cultivar caused a reduction in plant size, thus suggesting that it is possible to produce semidwarf plants from vigorous genotypes to consider them in high-density olive orchards.

EXTENSIN18 is required for full male fertility as well as normal vegetative growth in Arabidopsis.

EXTENSINS (EXTs) are a 65-member subfamily of hydroxyproline-rich glycoproteins (HRGPs) of which 20 putatively form crosslinking networks in the cell wall. These 20 classical EXTs are involved at the start of new wall assembly as evidenced by a requirement for EXT3 during cytokinesis, and the ability of some EXTs to polymerize in vitro into dendritic patterns. EXT3 was previously shown to form pulcherosine (three Tyrosines) cross-links. Little direct data exists on the other 19 classical EXTs. Here, we describe the phenotypes of ext18 mutants and rescued progeny as well as associated expression profiles of all 20 classical EXT genes. We found that EXT18 is required for full male fertility, as well as for normal vegetative growth. EXT18 has potential to form crosslinking networks via di-iso-di-tyrosine (four Tyrosines) covalent bonds, and not via pulcherosine due to deficit of lone Tyrosines. This together with ext18 defective pollen grains and pollen tubes, and reduced plant size, suggests that EXT18-type EXTs are important contributors to wall integrity, in pollen and other rapidly extending walls. The data also show that a knockout of EXT18 had a pleiotropic affect on the expression of several EXTs, as did the reintroduction of the native EXT18 gene, thus supporting the thesis that transcription of groups of EXTs are co-regulated and work in different combinations to make distinctive inputs into wall assembly of different cell types. These insights contribute to basic knowledge of cell wall self-assembly in different cell types, and potentially enable biotechnological advances in biomass increase and plant fertility control.

Temperature-stress resistance and tolerance along a latitudinal cline in North American Arabidopsis lyrata.

The study of latitudinal gradients can yield important insights into adaptation to temperature stress. Two strategies are available: resistance by limiting damage, or tolerance by reducing the fitness consequences of damage. Here we studied latitudinal variation in resistance and tolerance to frost and heat and tested the prediction of a trade-off between the two strategies and their costliness. We raised plants of replicate maternal seed families from eight populations of North American Arabidopsis lyrata collected along a latitudinal gradient in climate chambers and exposed them repeatedly to either frost or heat stress, while a set of control plants grew under standard conditions. When control plants reached maximum rosette size, leaf samples were exposed to frost and heat stress, and electrolyte leakage (PEL) was measured and treated as an estimate of resistance. Difference in maximum rosette size between stressed and control plants was used as an estimate of tolerance. Northern populations were more frost resistant, and less heat resistant and less heat tolerant, but—unexpectedly—they were also less frost tolerant. Negative genetic correlations between resistance and tolerance to the same and different thermal stress were generally not significant, indicating only weak trade-offs. However, tolerance to frost was consistently accompanied by small size under control conditions, which may explain the non-adaptive latitudinal pattern for frost tolerance. Our results suggest that adaptation to frost and heat is not constrained by trade-offs between them. But the cost of frost tolerance in terms of plant size reduction may be important for the limits of species distributions and climate niches.

Analysis of various liquid nitrogen pre-cooling schemes for large-scale helium liquefiers/refrigerators

Liquid nitrogen precooling is widely used in helium liquefier/refrigerator for increased liquefaction as well as providing initial cool-down up to 80 K. The advantages are reduction in plant size and in number of equipment. There are several configurations of liquid nitrogen precooling for helium plants have been proposed in literature and are being used in practice. The configurations mainly differ in number of equipment like heat exchangers, valves, dewars and the arrangement of helium and nitrogen streams. In this paper, through parametric analysis of some reported configurations using Aspen HYSYS® V7.3, design decisions for adopting a precooling scheme for given helium plant has been presented. Results have been analyzed for the adopted plant configuration to arrive at conclusion regarding optimum configuration for precooling in the helium plant.

Sustainable way for enhancing phosphorus efficiency in agricultural soils through phosphate solubilizing microbes

Phosphorus is the second important key element after nitrogen as a nutrient in terms of quantitative plant requirement. Although phosphorus is abundant in soils (organic and inorganic forms), its availability is restricted as it occurs mostly in insoluble forms. The phosphorus content in soil is about 0.05 per cent (w/w) but only 0.1 per cent of the total phosphorus is available to plant because of poor solubility and its fixation in every type of soil. An adequate supply of phosphorus during early phase of plant development is important for laying down the primordia of plant parts. It plays significant role in root ramification, thereby imparting vitality to plant. It also helps in seed formation and in early maturation of crops. Poor availability or deficiency of phosphorus markedly reduces plant size and growth. Phosphorus accounts about 0.2 - 0.8 per cent of the plant dry weight. To satisfy crop requirements, phosphorus is usually added to soil as chemical fertilizer, however, synthesis of chemical fertilizer is highly energy intensive processes, and has long term impacts on the environment in terms of eutrophication, soil fertility depletion, carbon footprint. Moreover, plants use only a small amount of phosphorus, because about 80–90 per cent of added phosphorus is precipitated by metal–cation complexes, and rapidly fixed in soils. Such environmental concerns have led to the search for sustainable way of phosphorus nutrition of crops. In this regards phosphate–solubilizing microorganisms have been seen as best eco–friendly means for phosphorus nutrition of crop. Although, several bacterial (Pseudomonas and Bacilli) and fungal strains (Aspergillus and Penicillium) have been identified as PSM. Their performance under in situ conditions is not reliable and therefore, needs to be improved by using co-inoculation techniques. This review focuses on the diversity of PSM, mechanism of P solubilization, role of various phosphatase, impact of various factors on solubilization, the present and future scenario of their use and potential for application of this knowledge in managing a sustainable agricultural system

Virus infection influences host plant interactions with non‐vector herbivores and predators

Summary Viruses are widespread in both natural and agricultural plant communities and can significantly alter diverse traits of their host plants that mediate key interactions with other organisms. Yet, the impacts of plant viruses on broader community dynamics remain little studied. Here, we explore the effects of Cucumber mosaic virus, a common non‐persistently transmitted plant virus, on short‐ and long‐term interactions of herbivorous and predatory insects with squash (Cucurbita pepo) plants in a weedy field setting, as well as virus‐induced changes in plant phenotypes that mediate these interactions. Cucumber mosaic virus has previously been shown to have numerous effects on host plants that likely influence interactions with arthropods, including reduced plant size, increased volatile emissions, and diminished plant quality and palatability for aphid vectors. Infection reduced the likelihood of many herbivorous insects arresting and feeding on plants, as well as the apparency of plants to herbivores that base in‐flight foraging on visual cues. In particular, infection drastically reduced numbers of a specialist squash herbivore (Anasa tristis) on plants in the field – a pattern likely driven by a reduction of phagostimulatory sugar levels in leaf tissue and concurrent increase in amino acid levels, as nymphal development was not obviously impacted by infection status. Relative to effects on herbivores, virus infection had little impact on the ability of predatory insects to locate aphid prey, although an experiment examining plant visitation in the absence of aphids revealed reduced numbers of foraging Syrphidae (Diptera) and Coccinellidae (Coleoptera) on infected plants but increased visitation and oviposition by Chrysopidae (Neuroptera). CMV infection may reduce overall herbivore pressure on infected plants through effects on palatability and apparency, yet predators appear to locate herbivorous prey that do occur on infected plants as efficiently as those on healthy plants. Virus infection can significantly influence plant interactions with the insect community (including non‐vector as well as vector insects) with potential implications both for disease spread and for broader community dynamics.

Integrated torrefaction vs. external torrefaction – A thermodynamic analysis for the case of a thermochemical biorefinery

Integrated and external torrefaction is analyzed and compared via thermodynamic modeling. In this paper, integrated torrefaction is defined as torrefaction integrated with entrained flow gasification. External torrefaction is defined as the decentralized production of torrefied wood pellets and centralized conversion of the pellets by entrained flow gasification. First, the syngas production of the two methods was compared. Second, the two methods were compared by considering complete biorefineries with either integrated torrefaction or external torrefaction. The first part of the analysis showed that the biomass to syngas efficiency can be increased from 63% to 86% (LHV-dry) when switching from external torrefaction to integrated torrefaction. The second part of the analysis showed that the total energy efficiency (biomass to methanol + net electricity) could be increased from 53% to 63% when switching from external torrefaction to integrated torrefaction. The costs of this increase in energy efficiency are as follows: 1) more difficult transport, storage and handling of the biomass feedstock (wood chips vs. torrefied wood pellets); 2) reduced plant size; 3) no net electricity production; and 4) a more complex plant design.

Nutritional deficiency in crisphead lettuce grown in hydroponics

The identification of nutrient deficiency symptoms in lettuce helps both producers and technical staff to keep the plant nutritional balance in their producing areas. The objective of this study was to evaluate production and describe and record the visual symptoms caused by the isolated or combined shortage of K, Ca, B and Zn in crisphead lettuce grown in hydroponics. The experimental design was completely randomized blocks with four replications and eight treatments, representing the single (K, Ca, B, Zn) and combined (Ca and B, K and Zn, B and Zn) omission of nutrients, with a control treatment containing a complete nutrient solution. We used the crisphead lettuce cultivar Rider Plus. Under Ca shortage, plant growth was reduced and chlorosis appeared in the borders of young leaves. K shortage was the most detrimental to production of shoot fresh and dry matter and root dry matter. Where B was absent, plant growth was limited, the apical dominance was lost and leaves became wrinkled. Plants without Zn showed mild chlorosis in the blade of young leaves, elongation and bending of petioles and reduction in root density. The combined omission of Ca and B slowed down plant growth and induced necrosis at the borders of young leaves, while the combined omission of K and Zn initially induced K deficiency symptoms with reduced growth. When B and Zn were simultaneously subtracted, plants first showed B deficiency symptoms: reduction in plant size as compared to the control treatment and death of the apical bud.