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Abstract Boron carbide (B 4 C) is an important type of neutron radiation shielding material with relatively high efficiency due to the high content of 10B element. Incorporation of B 4 C particles into polymer to prepare high-performance neutron radiation shielding material has become more and more important for the safe operation of nuclear power in the defense industry and nuclear power plant. The polyimide/B 4 C composite films with different micro-sized B 4 C contents were successfully prepared by in-situ polymerization. Silane coupling agent KH550 was employed to functionalize B 4 C particles to improve the dispersion of B 4 C particles in the polyimide matrix with strengthened interfacial interaction. As shown that the micro-sized B 4 C functional particles can be well dispersed in the BPDA/ODA polyimide matrix. With the B 4 C content increase, thermal stability of the polyimide/B 4 C composite films can be significantly improved, even mechanical properties partly declined. Meanwhile, the polyimide/B 4 C composite films exhibit good thermal neutron radiation shielding properties. The neutron permeability I/I 0 changes exponentially with the change of B 4 C content. When the B 4 C content is increased to 30 wt%, the polyimide/B 4 C composite films show optimum properties combination with thermal decomposition temperature (T d 10) of 622 °C, neutron permeability (I/I 0) of 0.24 (800 μm in thickness), and tensile strength of 406 MPa. The composite thus shows great potential for use in applications which require materials with high thermal stability and neutron radiation shielding ability, such as fusion reactor system and nuclear waste disposal. [ABSTRACT FROM AUTHOR]

The establishment, reproduction, dispersal, and distribution of alien plants are affected by various factors during the transition from being newly introduced in a habitat to being invasive. In the agro-pastoral ecotone of northern China, comprising farmlands and natural grasslands, the biological characteristics of alien plant species were the key intrinsic factors (propagation characteristics and competitive ability), followed by such extrinsic factors as human interference and environmental heterogeneity. Among biological characteristics, the life form may be an important and useful indicator of the invasive ability of a species, and the risk of invasion is greater from alien species that are poisonous, inedible, and have traits that facilitate wide dispersal. Farmlands may serve as initial shelters for alien species, from which they spread into neighbouring habitats, whereas natural grassland may act as a barrier to plant invasions. Management practices detrimental to grasslands, including overgrazing, reclamation, and road construction, often facilitate the invasions; therefore, counter measures such as reseeding and a ban on grazing need special attention. Environmental factors including precipitation, nutrients, prevailing winds, fires, and topography may be other factors that promote or block the process of invasion. In studying ways of preventing or controlling such invasions, alien plants with short life cycle, prolific seed production, and strong competitiveness, deserve particular attention and so do human activities that may damage the environment and fragile habitats. [ABSTRACT FROM AUTHOR]

• Eight years study of green roof plants in Beijing (Dwa climate). • Precipitation pattern greatly influence the plant growth and the community dynamics. • Species with rootstocks or thickened fibrous roots performed better. • Only Phediums aizoon was alive at all four substrate depths at the end of this study. • Substrate moisture content was more vital for plant survival than substrate depth. The selection of plants on green roofs should be tailored to the local climate. However, little is known about the long-term performance of plants in a Dwa climate (in the Köppen climate classification). This study follows the performance of 10 Crassulacean species (four species of Phedimus and six of Sedum) grown at four substrate depths (5, 10, 15, and 20 cm) over eight years on an unirrigated roof in Beijing, China. We found that the climate in Beijing, particularly the specific distribution of precipitation, had a substantial influence on plant growth and the community dynamics on extensive green roofs, and the dry and cold winters were the main factors that affected the plant survival on unirrigated green roofs. In such a climate, species with rootstocks or thickened fibrous roots performed better than species with entirely fibrous roots. Although deeper levels of substrate promoted better plant survival and performance, the species richness at all four depths continued to decrease. By the end of this research, only Phedimus aizoon and Phedimus floriferus 'Weihenstephaner Gold' still survived, and Phedimus aizoon was the only species that was alive at all of the four substrate depths. This research emphasized the importance of long-term research. The results of this study also revealed that the substrate moisture content was a more important factor than the substrate depth on the survival of plants over winter. To increase the rate of survival of plants on extensive green roofs over winter in Beijing, we advise the provision of supplementary irrigation before winter in years when the plants have experienced a dry autumn. [ABSTRACT FROM AUTHOR]

Microstructural and textural characteristics of Zr702 and Zr-2.5Nb alloys before and after rolling (50% reduction in thickness) were characterized and compared by employing electron channel contrast imaging and electron backscatter diffraction techniques, with underlying reasons for the differences between them explored. Results show that the starting microstructure of the Zr702 is mainly comprised of well-equiaxed α-Zr grains while the Zr-2.5Nb presents a typical dual-phase microstructure featured by bulk α grains enclosed by thin β-Zr films. After the 50% rolling, plastic deformation readily occurs through the active operation of prismatic and pyramidal slip in both the Zr alloys. Most grains are found to be elongated along rolling direction with a few less-deformed grains also present (more evident in the rolled Zr702). The β-Zr preexisting in Zr-2.5Nb alloy is softer than α-Zr and could thus be deformed more easily, allowing fewer plastic strains to be accommodated by the α grains. The starting Zr702 has a typical bimodal basal texture that is essentially unchanged after the 50% rolling. The majority of grains in the starting Zr-2.5Nb show scattered orientations with their c-axes away from normal directions (ND). After the same rolling, however, c-axes of most α-grains in the Zr-2.5Nb alloy are aligned to be close to transverse direction or ~30° from the ND (ring-like distribution), different from that of the Zr702. It is demonstrated that the formation of such textural features is related to the preexisting thin β films in the Zr-2.5Nb alloy, in addition to the slip deformation. • Plastic deformation readily occurs through active slip in Zr702 and Zr-2.5Nb alloys after 50% rolling. • Fewer strains are accommodated by α grains in rolled Zr-2.5Nb due to presence of soft β phase. • A few less-deformed grains with c//ND exist in both the rolled Zr alloys. • Major textural characteristics are hardly changed in the Zr702 before and after rolling. • Distinct textural characteristics are developed in the 50%-rolled Zr-2.5Nb. [ABSTRACT FROM AUTHOR]

Switchgrass (Panicum virgatum L.) shows great bioenergy potential and provides multiple ecological services. However, its severe seed shedding causes biomass waste and seed diffusion risk. Questions arise as to the production performance of switchgrass after panicle removal (PR), which remains unknown. We revealed switchgrass growth responses to PR and illustrated physiological reasons. Compared to the untreated switchgrass, PR significantly stimulated stem elongation (32.13%) and increased tiller number (39.70%), as well as aboveground biomass (24.69%). Importantly, PR significantly increased contents of nonstructural carbohydrates (NSCs) in the stem, which was directly beneficial to the ethanol conversion, and in the rhizome and root. The chlorophyll contents, net photosynthetic efficiency, and photochemical quantum efficiencies of flag leaf increased significantly. PR switchgrass allocated more assimilates into the stem, root, rhizome, and NSCs. Activities of phosphoenolpyruvate carboxylase, ribulose-1, 5-diphosphate carboxylase, sucrose phosphate synthase (SPS) in flag leaf and adenosine diphosphate glucose pyrophosphorylase (AGPase) and SPS in the stem and rhizome all increased significantly. In contrast, activities of the AGPase in flag leaf and sheath decreased significantly. Contents of zeatin nucleoside, gibberellins, and indoleacetic acid in flag leaf, stem, and rhizome all increased. Abscisic acid contents in flag leaf and stem decreased significantly while increased significantly in the rhizome. In conclusion, growth-promoting hormones delayed plant senescence, enhanced leaf photosynthesis, and enhanced vegetative growth through regulating assimilates-metabolism-related enzymes, which increased biomass accumulation in PR switchgrass. This work provided new insights for yield and digestibility improvement in switchgrass through field management practices, hormones regulation, or genetic modification strategies. [Display omitted] • Panicle removal (PR) retarded plant senescence in switchgrass. • PR increased biomass dry weights of switchgrass. • PR increased contents of nonstructural carbohydrates in stem, root and rhizome. • AGPase and SPS facilitated storage and transport of C assimilates in PR switchgrass. • Growth promoting hormones played critical roles in delaying plant senescence. [ABSTRACT FROM AUTHOR]

In this work, two Nb(Ta)TiZr medium-entropy alloy (MEA) coatings were fabricated successfully on a commercially pure Zr sheet by pulsed laser cladding. Their phase constitutions, microstructural characteristics, chemical compositions and grain orientations were well characterized and analyzed by using X-ray diffraction (XRD), electron channeling contrast (ECC) imaging, energy dispersive spectrometry (EDS) and electron backscatter diffraction (EBSD) techniques, with hardness and wear resistance measured and correlated with the microstructural characteristics as well. Results show that irregular-shaped bulk grains (BCC solid-solution phase) are formed in the two Nb(Ta)TiZr MEA coatings (cladding zones), both of which have a thickness of ∼800 μm with good metallurgical bonding to the substrate. After adding Ta, grains in the MEA coating are slightly refined. The phase constitutions in both the coatings agree with calculations based on several theoretical parameters. Hardness tests show that the NbTiZr and the NbTaTiZr coatings have hardnesses of 360 ± 18 HV and 430 ± 28 HV, respectively, ∼1.8 times and ∼2.2 times that of the substrate (196 ± 4 HV). This can be ascribed to combined effects of grain refinement strengthening, solid solution strengthening with denser low angle boundaries in the MEA coatings. Specific wear rates of the NbTiZr and the NbTaTiZr coatings are only ∼17% and ∼6% of that of the substrate, respectively, indicating markedly improved wear resistance. This is demonstrated to be closely related to complete oxide films easily formed on the coatings with oxidation and abrasive wear mechanisms. • Two Nb(Ta)TiZr MEA coatings were prepared on a pure Zr sheet by pulsed laser cladding. • The MEA coatings have a thickness of ∼800 μm and consist of irregular-shaped BCC phase. • Hardness and wear resistance of both MEA coatings are greatly improved compared to the substrate. • Their superior properties are related to grain refinement, solid solution and denser low angle boundaries. [ABSTRACT FROM AUTHOR]

Abstract A kind of silicone rubber (SR)/paraffin (Pa)@silicon dioxide (SiO 2) composite form-stable phase change material (PCM) was developed in this paper. Pa@SiO 2 was obtained by choosing Pa as PCM core microencapsulated in SiO 2 shell based on tetraethoxysilane (TEOS) and γ-aminopropyl triethoxysilane (APTES) as precursors, then Pa@SiO 2 microencapsules were embedded in SR matrix to fabricate SR/Pa@SiO 2 composites. The SiO 2 shell can provide a barrier for the melted Pa and meanwhile have reinforcing effect on SR as inorganic filler. The in-situ modification of SiO 2 shell using APTES owing to the amino groups can not only prevent agglomeration, but also increase interfacial bonding between Pa@SiO 2 with SR. The thermal and mechanical properties of the form-stable PCMs were characterized by differential scanning calorimetry (DSC) and mechanical tests. The results showed that the thermal and mechanical properties of SR/Pa@SiO 2 composites were better than those of SR/Pa and SR/Pa/SiO 2. Leakage test was conducted by heating the prepared composites over the melting temperature of Pa. The SR/Pa@SiO 2 composites were found as form-stable PCM with low leakage rate. The phase change latent heat of the SR/Pa@SiO 2 composites was up to 92.39 J g−1 and the composites can be used for thermal energy storage. Highlights • Developed a novel and efficient process for amino terminated paraffin (Pa)@SiO 2 microencapsules. • The Pa@SiO 2 microencapsules were embedded in silicone rubber (SR) matrix to fabricate SR/Pa@SiO 2 composites. • The SiO 2 shell can provide a barrier for the melted Pa and meanwhile have reinforcing effect on SR as inorganic filler. • The phase change latent heat of the SR/Pa@SiO 2 composites was up to 92.39 J g−1. [ABSTRACT FROM AUTHOR]

Abstract A series of paraffin/expanded graphite (EG) composites with various mass fraction were prepared. The microscopic geometry configuration, thermal conductivity and saturation sorption capacity of EG were obtained. In this paper, a method based on the experiments of EG pores was proposed for constructing geometric models. The geometric model constructed by this method has obvious anisotropy and has been employed in the calculation. Furthermore, the numerical results of thermal conductivity indicate anisotropy of a single-pore. Moreover, it had been observed by experiment that the anisotropy is weakened and transformed to isotropy in the process of combining geometric models with a large number of single pores. The final numerical results agree well with the experiments, which validates the precision and reliability of the proposed model. The increasement of thermal conductivity is also calculated and discussed during the phase change process of paraffin/EG. Highlights • A method of EG pores was proposed for constructing geometric models which has obvious anisotropy. • The SEM micrograph and saturation sorption capacity are employed to build the geometric models of EG pores. • Effective thermal conductivity during non-phase change process and the phase change process was calculated. • The numerical results agree well with the experiments. [ABSTRACT FROM AUTHOR]

In the research of wide-range light-absorbing coordination polymers, to enhance intermolecular or intramolecular charge transfer (CT) and decrease the electron transition excitation energy, a dedicatedly designed novel pyridine diketopyrrolopyrrole (DPP) ligand with strong electron-withdrawing unit were introduced into the Zn, Cu and 1,4-benzenedicarboxylic acid (BDC) based coordination frameworks and porous coordination polymers DPP-Zn(BDC) and DPP-Cu(BDC) were obtained, respectively. By comparing study with physically-mixed samples DPP + Zn(BDC) and DPP + Cu(BDC), a fresh light-absorbing peak around 720 nm is observed and makes the samples exhibit a wide-range absorption in the range of 200–1400 nm and gives another experimental evidence for the research of charge transfer effect in naphthalenediimide-based metal-organic framework Zn 2 (NDC) 2 (DPNI) (J. Phys. Chem. Lett. 2013, 4, 453–458). The tremendous red-shift of absorbing onset wavelength could be ascribed to the enhanced intermolecular or intramolecular CT due to electron-withdrawing DPP ligands. At the mean time slow-photon effect is also discussed. The materials have been also characterized through powder XRD, FT-IR, SEM, XPS, solution-state spectra techniques and etc. This study underscores the importance of analyzing the extended structure for interpreting photophysical data based on the potential factors: CT, slow photon, or J-coupling. Moreover the research work might inspire the construction of light-responsive coordination polymers or metal-organic frameworks (MOFs) for charge or electron transfer. [ABSTRACT FROM AUTHOR]

The surface characterization and electrostatic property of Hybrid Pennisetum (HP) after alkaline sulfite pretreatment were explored for enhanced enzymatic hydrolysability. The O/C ratio in HP increased from 0.34 to 0.60, and C1 concentration decreased from 62.5% to 31.6%, indicating that alkaline sulfite pretreatment caused poorer lignin but richer carbohydrate on HP surface. Zeta potential and sulfur element analysis indicated that more enzymes would preferably adsorb on the carbohydrate surface of alkaline sulfite pretreated HP because the lignin was sulfonated, which facilitated the decrease of non-productive adsorption. Glucose yield of alkaline sulfite pretreated HP reached to 100% by synergistic action of cellulase and xylanase in the hydrolysis, which was significantly higher than that of NaOH pretreated, and the concentration of glucose released was 1.52 times higher. The results suggested that alkaline sulfite pretreatment had potential for improving the HP hydrolysability, and the surface characterization and electrostatic property facilitated the enzymatic digestibility. [ABSTRACT FROM AUTHOR]

Novel microencapsulated phase change materials (MEPCMs) with high encapsulation capacity and enhanced leakage-prevention performance were prepared by in situ polymerization. For these MEPCMs, paraffin and melamine-formaldehyde resin (MF) are respectively used as core and shell, and graphene oxide (GO) nanosheets, which can be seen as extra protective screen, are situated at the interface between the core and the shell. Effects of GO on morphology, microstructure and properties of MEPCMs were characterized by scanning electronic microscopy (SEM), laser diffraction particle analyzer, atomic force microscopy (AFM), Fourier transformation infrared spectroscopy (FTIR), X-ray diffractometry (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and paraffin leakage rate test. The results show that the fabricated MEPCMs with GO nanosheets have gradual increasing average diameters from 6.32 to 15.89 μm with an increase content of GO, while the size of MEPCMs without GO is 5.63 μm. When the time of leakage rate test is 50 h, the MEPCMs prepared with 0.5 mg/mL GO aqueous dispersion have considerably high encapsulation ratio of 93.9 wt.%, and the leakage rate is reduced by 93.1% compared with those without GO. The high encapsulation capacity and enhanced leakage-prevention performance might be highly attractive for the application of MEPCMs. [ABSTRACT FROM AUTHOR]

Switchgrass ( Panicum virgatum L.) has been developed into a major herbaceous bioenergy crop for the production of cellulosic biofuels in North America and many counties in European. As cultivar selection has a major impact on the ultimate biomass productivity, we evaluated the adaptability and yield potential of 12 switchgrass cultivars including both upland and lowland ecotypes from 2010 to 2013 in the Beijing region, Northern China. Plant height was measured after anthesis, but phytomer number and tiller density were investigated at harvest. One single autumn harvest was carried out each year and biomass yields were determined. It was found that the lowland cultivars ‘Alamo’, ‘Kanlow’ and ‘NewYork’ produced the most biomass for their better performances in number of phytomers per tiller and mass per phytomer, though upland cultivars had higher tiller density. ‘Cave-in-rock’ and ‘Trailblazer’ had better biomass production among the upland cultivars and they were also recommended for planting together with lowland ones for their excellent cold tolerance in this region. [ABSTRACT FROM AUTHOR]

1-ethyl-3-methylimidazolium acetate ([EMIM] AC) pretreatment at moderate temperatures (60 °C and 75 °C) was evaluated for improving hydrolysability of Chinese pennisetum, a leading candidate as an energy crop, for bioethanol production. The pretreatment caused slight carbohydrate and lignin loss but significantly changed the material physicochemical characters, such as crystallinity and surface structure. Both changes exhibited positive effects on improving the enzymatic digestibility of the Chinese pennisetum. It was observed that approximately 90% of the cellulose and 50% of the xylan in the Chinese pennisetum after pretreatment at 75 °C were converted to fermentable monosaccharides by the combined cellulases and endo-xylanase. The results suggested that Chinese pennisetum could be effectively pretreated with ([EMIM] AC) pretreatment at moderate temperatures, and the high hydrolysis yield of fermentable sugars from pretreated Chinese pennisetum could be achieved by the synergistic action of accessory xylanase in enzymatic hydrolysis by cellulases. [ABSTRACT FROM AUTHOR]

Thermally conductive form-stable phase change materials (FSPCMs) were prepared by using ethylene-vinyl acetate (EVA), paraffin, expanded graphite (EG) and carbon fiber (CF) as row materials. Two-dimensional EG and one-dimensional CF were used as thermally conductive fillers. Paraffin and EVA were phase change material (PCM) and supporting material, respectively. Differential scanning calorimetry (DSC) and leakage rate testing results indicated that FSPCMs owned the melting temperature of 45.63 °C and the latent heat of 167.4 J/g. The prepared material had a small leakage rate which was less than 2%. Scanning electron microscope (SEM) results shown that EG and CF possessed excellent compatibility in FSPCMs. In-situ X-ray diffraction (XRD) tests demonstrated that the crystal behaviors of paraffin and EVA were changed with the phase transformation. Thermal conductivity results shown that thermal conductivity of FSPCMs in horizontal orientation was higher than that in longitudinal orientation. EG and CF have synergistic enhancement to thermal conductivity of FSPCMs. [ABSTRACT FROM AUTHOR]

The effects of aqueous ammonia pretreatment on structural properties and hydrolysabilities of Chinese Pennisetum and Hybrid Pennisetum were investigated. Aqueous ammonia pretreatment increased cellulose crystallinities and hydrolysabilities of Chinese Pennisetum and Hybrid Pennisetum. Compared with Chinese Pennisetum, Hybrid Pennisetum showed better enzymatic digestibility. Xylanase supplementation was more effective than the increase of cellulase loadings in the hydrolysis of aqueous ammonia pretreated Chinese Pennisetum and Hybrid Pennisetum. After supplementation of 2 mg of xylanase/g dry matter to 5 FPU of cellulases/g dry matter, the hydrolysis yields of cellulose of aqueous ammonia pretreated Chinese Pennisetum and Hybrid Pennisetum were 92.3–95.4%, and the hydrolysis yields of xylan were 86.9–94.2%. High hydrolysability and low dosage of enzyme loadings together with the advantages of high yield and widely distribution demonstrated the potential of Chinese Pennisetum and Hybrid Pennisetum for the production of platform sugars. [ABSTRACT FROM AUTHOR]

So far no successful artificial hybridizations among ornamental grasses in the Pennisetum Rich. (Poaceae) genus that are widely applied in landscape design have been reported because of unclear genetic backgrounds and uncertain evolutionary and genetic relationships among one another, severely restricting the number of ornamental cultivars and their gardening utility. The present study aims to reveal genetic backgrounds and relationships for nine Pennisetum ornamental grasses via karyotype diversity analysis; discuss the morphological classification system proposed in previous studies on morphological, chromosomal and genomic levels; and verify the chromosomal evolution of Pennisetum genus using the combined karyotypic and genomic data. Our results indicated that (1) traditional morphological classification system of Pennisetum genus is reasonable, both from the morphological and cytological points of view; (2) hybridization among Pennisetum alopecuroides , P. alopecuroides ‘Little Bunny’, P. alopecuroides ‘Moudry’ and P. orientale may be easier to obtain a hit; (3) chromosomes with lower basic chromosome number are more asymmetry than those chromosomes with higher basic chromosome number, and taxa with different basic chromosome numbers may have experienced different way of speciation; and (4) chromosomal evolution in Pennisetum genus progressed from a symmetrical to an asymmetrical order in the course of evolution; and the structure of the genome of Pennisetum species involved in the reduction of chromosome number and an increase in their sizes and DNA contents. The present study guides the breeding programs and genome projects of Pennisetum ornamental grasses practically, and provides references for the evolutionary studies on Pennisetum genus theoretically. [ABSTRACT FROM AUTHOR]

• ZjNYC1 was localized in the chloroplasts and interacts with ZjNOL in vivo. • Overexpression of ZjNYC1 accelerated the degradation of chlorophyll, and promoted senescence. • Integrated analysis of JIP-test and RNA-seq revealed ZjNYC1 negatively affected the integrity and functionality of photosystem. Chlorophyll plays essential roles in photosynthesis and its degradation should be regulated precisely. Chlorophyll b reductase encoded by the gene NYC1 is responsible for catalyzing chlorophyll b degradation and maintaining the stability of photosystems. Although NYC1s have been characterized in many plants, their function in the photosynthetic machinery and the underlying regulatory mechanisms at the whole transcriptome level remain elusive. In this study, the ZjNYC1 gene was cloned from the important warm-season turfgrass Zoysia japonica. Analysis of the subcellular localization revealed that ZjNYC1 was localized in the chloroplasts, and results of the bimolecular fluorescence complementation (BiFC) assay indicated that ZjNYC1 could interact in vivo with the NYC1-like protein, ZjNOL. Overexpression of ZjNYC1 accelerated the degradation of chlorophyll, and promoted senescence with accumulation of ABA and reactive oxygen species (ROS) in Arabidopsis. Expression of ZjNYC1 rescued the stay-green phenotype of the Arabidopsis nyc1 mutant. An integrated analysis of chlorophyll fluorescence test (JIP-test) and RNA-sequencing revealed that ZjNYC1 negatively affected the efficiency of the PSII, PSI, and the intersystem electron transport chain. Furthermore, the Calvin cycle and photorespiration were suppressed, but ABA and ethylene synthesis and signal transduction pathways were activated in the transgenic lines. Collectively, these results demonstrated that ZjNYC1 plays important roles in accelerating chlorophyll degradation and senescence, and caused negative affect on the integrity and functionality of the photosystems. [ABSTRACT FROM AUTHOR]

A strategy to combat the adverse effects of urbanization involves the installation of green roofs under different climatic conditions. The design and maintenance of green roof systems need to be tailored to the local climate. However, there is a scarcity of reports on the performance of plants under temperate monsoonal climatic conditions. This study follows the growth pattern of 28 species (18 non-succulent forbs and 10 succulents) grown at three substrate depths (10, 15, and 20 cm) over three years on an unirrigated extensive green roof, located in Beijing, China. The results of this study revealed that sustainable extensive green roof was realizable without irrigation in Beijing. In terms of plant adaptive strategies, the most successful plants in this study were the stress-tolerant species, followed by the ruderal species. While deeper substrate could facilitate the survival and performance of plants, substrate moisture content was more significant for the survival of plants in the dry and cold winter in Beijing. This study recommended the use of a substrate depth, which was at least 15 cm deep for unirrigated green roofs in Beijing. Unlabelled Image • A green roof research was conducted in a temperate monsoonal climate. • Stress-tolera\nt species and ruderal species performed well on unirrigated green roofs. • Substrate moisture content was vital for the plant survival in dry and cold winters. • Substrate depth should be at least 15 cm for unirrigated green roofs in Beijing. [ABSTRACT FROM AUTHOR]

Polyploidization is regularly regarded as an important tool for the generation of innovative germplasm resources and plant breeding. In this study, autopolyploid switchgrass lines were produced from calli derived from immature inflorescence of tetraploid switchgrass ( Panicum virgatum L.), both lowland cv. Alamo and Kanlow, and upland cv. Ranlow, through colchicine treatments. Ploidy levels of plantlets regenerated from the calli were screened by flow cytometry. Growth characteristics of the tetraploid and octoploid switchgrass cultivars were further investigated in a field experiment. Compared with the tetraploid plants of the three switchgrass cultivars, the corresponding octoploid plants showed significant reduction in plant height, number of tillers per plant and fresh matter, but an increase in leaf length and width. [ABSTRACT FROM AUTHOR]