Main Allelochemicals from the Rhizosphere Soil of Saussurea lappa (Decne.) Sch. Bip. and Their Effects on Plants’ Antioxidase Systems

Allelochemicals are the media of allelopathy and form the chemical bases of plant-environment interactions. To determine true allelochemicals and their autotoxic effects, seven compounds were isolated and identified from in-situ sampled rhizosphere soil of cultivated Saussurea lappa. Of these; costunolide (2), dehydrocostus lactone (3) and scopoletin (4) showed significant inhibition on seedling growth in a concentration-dependent manner. Detection and observation demonstrated that the antioxidase system was found to be affected by these chemicals, resulting in the accumulation of ROS and membrane damage. To investigate their release ways, the compounds were traced back and volumes quantified in rhizosphere soil and plant tissues. This work made clear the chemical bases and their physiological effects on the plants. These chemicals were found to be the secondary metabolites of the plants and included in the rhizosphere soil. The findings identified a potential pathway of plant-plant interactions, which provided theoretical basis to overcoming replanting problems. This research was also useful for exploring ecological effects of allelochemicals in green agriculture

Codonopilate A, a Triterpenyl Ester as Main Autotoxin in Cultivated Soil of <i>Codonopsis pilosula</i> (Franch.) Nannf

Codonopilate A (<b>1</b>), a triterpenyl ester, was isolated from monocultivated soil of annual <i>Codonopsis pilosula</i> and identified as the main autotoxin. The yield ratio of codonopilate A in dried soil was calculated as 2.04 μg/g. Other two triterpenoids, taraxeryl acetate (<b>2</b>) and 24-methylenecycloartanol (<b>3</b>), were isolated and identified as well showing weaker autotoxity. This was the first time that the potential allelochemicals and autotoxins in the cultivated soil of <i>Codonopsis pilosula</i> were reported. Accumulation of reactive oxygen species (ROS) induced by the autotoxins in the root tips of <i>Codonopsis pilosula</i> was considered as an important factor for the phytotoxic effect. This work systematically investigates the allelopathic and autotoxic effect of <i>Codonopsis pilosula</i>, and the preliminary autotoxic action mode of the three autotoxins. These findings are helpful to understand the molecular mechanism of autotoxicity and conducive to explore proper ways to degrade the autotoxins and eliminate the replanting problems of <i>Codonopsis pilosula</i>

Impact behavior of nylon kernmantle ropes for high-altitude fall protection

Aiming at the problem that the existing rope falling device can only detect the impact force and cannot synchronously detect the impact displacement, this paper introduces a large-range high-precision displacement sensor and constructs a rope impact force-displacement detection device. Taking the nylon kernmantle rope for high-altitude fall protection commonly used in aerial work and rock climbing as the research object, the impact response behavior of the rope when drop mass is dropped once and repeatedly is systematically studied, and the impact force and impact displacement are discussed. Further, the evolution of the elastic modulus of the rope is discussed and this could provide theoretical support for the design of the impact-resistant rope structure and the rope impact protection

Allelochemicals from the Rhizosphere Soil of Cultivated Astragalus hoantchy

Astragalus hoantchy, a widely cultivated medicinal plant species in traditional Chinese and Mongolian medicine, has been often hampered by replant failure during cultivation, like many other herbs of the genus Astragalus. Root aqueous extracts of Astragalus herbs were reported to exhibit allelopathic activity against other plants and autotoxic activity on their own seedlings, but the allelochemicals released by Astragalus plants have not been specified so far. Ten compounds were isolated from the rhizosphere soil extract of cultivated A. hoantchy and elucidated by spectroscopic analysis. Compounds <b>1</b>–<b>6</b> observably showed allelopathic activity against Lactuca sativa seedlings and autotoxic activity against A. hoantchy seedlings. The isolated compounds were further confirmed and quantified by high-performance liquid chromatography (HPLC) in the rhizosphere soil, with a total concentration of 9.78 μg/g (dry weight). These results specify and verify the allelochemicals released by cultivated A. hoantchy into the soil environment, which may provide new insights into the allelopathic mechanisms of this medicinal plant and probably assist in clarifying the replant problems of Astragalus plants

Cycloartane-type triterpenoids from <i>Astragalus hoantchy</i> French.

<p>A new cycloartane-type triterpenoid, 3β-acetoxy-9β,19-cyclolanost-24<i>E</i>-ene-1α,16β-diol-27-<i>O</i>-β-d-glucopyranoside (<b>1</b>), together with three known ones (<b>2</b>–<b>4</b>) were isolated from the aerial parts of <i>Astragalus hoantchy</i>. The structure of compound <b>1</b> was elucidated by detailed spectroscopic analyses including 1D and 2D NMR, HRESIMS, and IR experiments. All of the four compounds were isolated from <i>A. hoantchy</i> for the first time. The antifungal activities of compounds <b>1</b>–<b>4</b> against a phytopathogenic fungus (<i>Alternaria solani</i>) were evaluated with the result that compound <b>3</b> exhibited a moderate activity with an IC₅₀ value of 284 μg/mL.</p

Nematicidal activity against Aphelenchoides besseyi and Ditylenchus destructor of three biflavonoids, isolated from roots of Stellera chamaejasme

Aphelenchoides besseyi and Ditylenchus destructor can cause serious problems for a number of important agricultural crops and vegetables. In this study, the ethanol extract of Stellera chamaejasme L. roots showed strong nematicidal activity against Aphelenchoides besseyi and Ditylenchus destructor. By using a bioactivity-driven fractionation, three biflavonoids were isolated from the extract and their structures were identified by mass and nuclear magnetic resonance spectral data. Nematicidal activity bioassays revealed that isoneochamaejasmin A had the strongest nematicidal activity against A. besseyi and D. destructor with LC50 values of 2.32 and 0.18 mM at 72 h, respectively. Chamaejasmenin B displayed weaker nematicidal activity against A. besseyi with an LC50 value of 3.94 mM at 72 h. Neochamaejasmin B induced the lowest mortality against D. destructor with an LC50 values of 15.6 mM at 72 h. These results suggested that the kind and position of substitutions and the relative configuration of 2-H/3-H and 2 ''-H/3 ''-H could be considered as important factors responsible for the nematicidal activity of these purified C-3/C-3 '' biflavonoids

NTIRE 2022 Challenge on Stereo Image Super-Resolution: Methods and Results

In this paper, we summarize the 1st NTIRE challenge on stereo image super-resolution (restoration of rich details in a pair of low-resolution stereo images) with a focus on new solutions and results. This challenge has 1 track aiming at the stereo image super-resolution problem under a standard bicubic degradation. In total, 238 participants were successfully registered, and 21 teams competed in the final testing phase. Among those participants, 20 teams successfully submitted results with PSNR (RGB) scores better than the baseline. This challenge establishes a new benchmark for stereo image SR