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• 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]

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]

• 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]