Soil temperature and moisture regulate seed dormancy cycling of a dune annual in a temperate desert

Plants have evolved diverse strategies to ensure their survival and regeneration in specific environments. Although temperature and soil moisture control seed dormancy, most studies have concentrated on temperature and little is known about the influence of moisture for species in the arid region. Responses of seed dormancy and germination of Agriophyllum squarrosun (Amaranthaceae), a pioneer and dominant species in Mu Us Sandland in northern China, to variations in soil moisture and temperature were examined. Our study showed that (1) freshly harvested seeds were in non-deep physiological (conditional) dormancy; (2) seeds in the soil exhibited dormancy cycling being non-dormant in spring and dormant from summer to autumn; (3) dry conditions at cold or warm temperatures alleviated dormancy; (4) germination was promoted by wetting-drying cycles; and (5) dormancy was induced by warm temperature (15/25 degrees) and particularly low soil moisture less than 14.0%. The seasonal pattern of seed dormancy/germination was regulated by seasonal rainfall and soil temperature. At the same time, a range of conditions enable dormancy break and germination regardless of soil moisture conditions allowing the species to persist in an unpredictable environment

Soil salt and NaCl have different effects on seed germination of the halophyte Suaeda salsa

Seed germination is a key life-history stage of halophytes. Most studies on seed germination of halophytes have focused on the effects of a single salt, while little information is available on the effects of mixed salt in the natural habitat. Due to the contribution of multiple ions in saline soil, we hypothesized that the effect of mixed salt on seed germination will differ from that of a single salt and the mechanism of how germination is affected will differ as well. The effects of mixed salt and NaCl on germination, water imbibition, and ionic concentrations of seeds of Suaeda salsa (L.) Pall. were compared at various salinity levels. Germination percentage (GP) and rate (GR) decreased with increasing salinity level, regardless of salt type. There was no difference in GP or GR between mixed salt and NaCl when the salinity level was below 20 dS m(-1). Above 20dS m(-1), GP and GR in NaCl were lower than those in mixed salt. At the same salinity level, Na+ concentration in seeds was higher in NaCl than that in mixed salt, but the reverse was true for Ca2+ and Mg2+ concentrations. Imbibition rate for seeds in NaCl was lower than that in mixed salt at the same salinity level. Addition of Ca2+ and Mg2+ alleviated the inhibition of NaCl on seed germination. In conclusion, our results suggest that the effects of soil salts and NaCl on seed germination are different, and using NaCl instead of soil salt might not be realistic to show the effect of saline stress on seed germination of halophytes in the natural habitat

Simultaneous optimization of the acidified water extraction for total anthocyanin content, total phenolic content, and antioxidant activity of blue honeysuckle berries (Lonicera caerulea L.) using response surface methodology

The purpose of this study was to optimize the total anthocyanin content (TAC), total phenolic content (TPC), and antioxidant activity of acidified water extract from blue honeysuckle berries by response surface methodology (RSM). The optimized conditions were HCl concentration of 0.35%, liquid–solid ratio of 49.42 ml/g, and extraction temperature of 41.56°C for total anthocyanin content (24.01 ± 0.37 mg/g), total phenolic content (207.03 ± 3.31 mg/g), DPPH radical scavenging activity (68.24 ± 1.13%), and ABTS radical scavenging activity (70.05 ± 0.84%). The experimental results are consistent with the predicted values. The results showed that acidified water extraction was an effective, simple, and green technique for the extraction of total anthocyanins, total phenol, and antioxidant activity from blue honeysuckle berries

Seed dormancy and germination of a critically endangered plant, Elaeagnus mollis, on the Loess Plateau of China

Elaeagnus mollis is an endangered species narrowly distributed on the south-eastern Loess Plateau of China. Natural regeneration of populations is highly restricted by low seed germination. The aim of this study was to explore why germination is low and how to enhance germination of the species. Field and laboratory experiments were carried out to examine the effects of temperature, light, drought and NaCl on seed germination and the effects of the seed coat, GA(3), cold and warm stratification and after-ripening on dormancy release. Our results showed that (1) fruits (0.65 g/fruit) and seeds (0.14 g/seed) were relatively large, the embryo was surrounded by a hard and permeable seed coat and a lignified calyx tube, and more than half of the fresh seeds were not viable; (2) fresh, intact seeds did not germinate, but germination of scarified seeds was highest at 5/15 degrees C in continuous darkness; (3) dormancy was not released by GA(3) and cold stratification (5 degrees C), but significantly released by variable temperature stratification and field burial, indicating that seeds had deep physiological dormancy; and (4) germination was significantly enhanced by median drought (-0.6 MPa) and NaCl (0.34 M), and decay was inhibited beyond -0.4 MPa osmotic potential and 0.225 M NaCl. Our results suggested that, with habitat loss and climate warming, regeneration from seeds in natural populations will continue to be negatively affected, and the range of the populations will further contract

Net plant interactions are highly variable and weakly dependent on climate at the global scale

14 páginas.- 6 figuras.- 1 tabla.- referencias.- Additional supporting information may be found in the online version of the article at the publisher’s websiteAlthough plant–plant interactions (i.e. competition and facilitation) have long been recognised as key drivers of plant community composition and dynamics, their global patterns and relationships with climate have remained unclear. Here, we assembled a global database of 10,502 pairs of empirical data from the literature to address the patterns of and climatic effects on the net outcome of plant interactions in natural communities. We found that plant interactions varied among plant performance indicators, interaction types and biomes, yet competition occurred more frequently than facilitation in plant communities worldwide. Unexpectedly, plant interactions showed weak latitudinal pattern and were weakly related to climate. Our study provides a global comprehensive overview of plant interactions, highlighting competition as a fundamental mechanism structuring plant communities worldwide. We suggest that further investigations should focus more on local factors (e.g. microclimate, soil and disturbance) than on macroclimate to identify key environmental determinants of interactions in plant communities.This work was supported by the National Natural Science Foundation of China (32071524, 31770514 and 31870711). International research travel by J.H.C.C. was partly funded by the Royal Netherlands Academy of Arts and Sciences (KNAW, CEP grant 12CDP007).Peer reviewe

Electron-ion collider in China

International audienceLepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a polarization of ∼80%) and protons (with a polarization of ∼70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2–3) × 10$^{33}$ cm$^{−2}$ · s$^{−1}$. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.[graphic not available: see fulltext