Phytotoxic effect of Haldina cordifolia on germination, seedling growth and root cell viability of weeds and crop plants

Abstract Background Plant rivalry primarily involves resource competition, where one plant extracts resources from its neighboring counterparts. Interference competition, in contrast, refers to a direct form of interference that obstructs access to resources and is common among animals capable of physical combat. In plants, one of the main manifestations of interference competition is allelopathy. Allelopathic plants exude cytotoxic substances into their environment to gain a competitive advantage over nearby plants when resources are scarce. Allelopathy occurs within complex soil ecosystems where microbes in the rhizosphere can break down, modify or boost the chemicals released by plants to modulate their effects. Nevertheless, the environmental and ecological factors that govern the production and persistence of allelochemicals remain poorly understood. Despite its evident ecological significance, allelopathy is rare among plants and the reasons behind its limited evolutionary development are not fully understood. Main body This review critically examines the interactions between plant allelochemicals and soil microbiomes, reporting existing literature and highlighting both beneficial and detrimental relationships influencing allelochemicals. Furthermore, the review investigates novel methodologies, including metagenomics and stable isotope probing, that enhance our comprehension of these intricate interactions. Conclusion A thorough understanding of how the chemical and physical characteristics of soil affect the stability and efficacy of allelochemicals over extended periods in real-world field scenarios is still lacking. Bridging this knowledge gap is essential for the advancement of sustainable agricultural practices that harness allelopathic interactions to improve crop resilience and enhance ecosystem stability.

The Allelopathic Activity of Festuca arundinacea Shreb. Rhizospheric Soil Is Exacerbated Under Drought Stress

The viability of Zea mays seed plays a critical role in determining the yield of corn. Therefore, developing a fast and non-destructive method is essential for rapid and large-scale seed viability detection and is of great significance for agriculture, breeding, and germplasm preservation. In this study, hyperspectral imaging (HSI) technology was used to obtain images and spectral information of maize seeds with different aging stages. To reduce data input and improve model detection speed while obtaining more stable prediction results, successive projections algorithm (SPA) was used to extract key wavelengths that characterize seed viability, then key wavelength images of maize seed were divided into small blocks with 5 pixels ×5 pixels and fed into a multi-scale 3D convolutional neural network (3DCNN) for further optimizing the discrimination possibility of single-seed viability. The final discriminant result of single-seed viability was determined by comprehensively evaluating the result of all small blocks belonging to the same seed with the voting algorithm. The results showed that the multi-scale 3DCNN model achieved an accuracy of 90.67% for the discrimination of single-seed viability on the test set. Furthermore, an effort to reduce labor and avoid the misclassification caused by human subjective factors, a YOLOv7 model and a Mask R-CNN model were constructed respectively for germination judgment and bud length detection in this study, the result showed that mean average precision (mAP) of YOLOv7 model could reach 99.7%, and the determination coefficient of Mask R-CNN model was 0.98. Overall, this study provided a feasible solution for detecting maize seed viability using HSI technology and multi-scale 3DCNN, which was crucial for large-scale screening of viable seeds. This study provided theoretical support for improving planting quality and crop yield.

ABSTRACT: Herbicide application is an effective weed control method for mitigating crop yield loss; however, herbicide overuse can cause toxicity in non-target plants. The present study evaluated the effects of glufosinate at recommended dose for agricultural application (0.45 kg ha-1) and at overuse dose (0.90 kg ha-1) glufosinate application on photosynthetic performance and nitrogen assimilation of the rapeseed varieties D148 and Zhongshuang 11 (ZS11). Both glufosinate concentrations significantly decreased the content of chlorophyll and nitrogenous compounds, except free proline, and the activity of glutamine synthetase and glutamate synthase, and increased the activity of glutamic acid dehydrogenase in both varieties. When the concentration of glyphosate was 0.45kg ha-1, the nitrogen assimilation of the two varieties decreased, which indicated that the recommended dosage inhibited the nitrogen assimilation of the two varieties; however, the increase of net photosynthetic rate of D148 and the decrease of that of ZS11 mean that D148 is more tolerant to the recommended dose of glyphosate than ZS11. The 0.90 kg ha-1 dosage was toxic to both rapeseed varieties. Overall, our results indicated that herbicide overuse inhibited the photosynthetic rate and nitrogen assimilation in rapeseed seedlings, and it is essential to apply a suitable glufosinate dose based on the variety grown to minimize adverse effects on crops and environment.

Mimosa pigra L. (Fabaceae), commonly known as giant mimosa, is one of the major invasive species, constituting a serious threat to agricultural crops and other plants in the biodiversity. With this study, we aimed to investigate the mechanism underlying the effects on plant growth and development upon exposure to two coumarins. Protein solutions were obtained from giant mimosa seedlings that had been exposed to the coumarins, and they were analyzed with the shotgun proteomic method by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The proteins were identified in seedlings treated with coumarins. The control plants expressed 621 proteins, the plants treated with isoscopoletin expressed 613 proteins, and the plants treated with umbelliferone expressed 640 proteins. The classification of proteins by PANTHER software found that the coumarins interfered with proteins involved in cellular component organization or biogenesis and metabolic processes. STITCH analysis of protein expression after treatment with coumarins confirmed that CUL4, ESF, LNG2 and SCD2 played a role in plant growth and development. WAK1 and WAT1 were involved in cell wall and cell surface responses. At3g61030 and CIP111 were related to Ca2+ accumulation and CAND1, CUL4 and ML5 were linked with programmed cell death. It is worthwhile to mention that coumarins increased morphological changes in the epidermis, Ca2+ accumulation in the roots and protein expression in plant growth and development, morphological changes, Ca2+ accumulation as well as in programmed cell death.

Allelopathy is an ecological phenomenon consisting of both positive and negative effects between organisms determined by the release of secondary metabolites into the environment. Root exudation represents the most important pathway of releasing allelochemicals. Once released into the soil, allelochemicals interact with the organic and inorganic soil phases, as well as with soil microorganisms. The set of these interactions fix allelochemicals bioavailability and phytotoxic level. Here we critically review the interactions between plant allelochemicals and physical, chemical and biological soil characteristics by reporting the literature available and pointing out both positive and negative relationships affecting allelochemicals phytotoxicity and nutrient availability. In addition, we have reported a qualitative balance of allelochemicals in the soil. Thirdly, we reviewed the exudation process of allelochemicals and the transport mechanisms across plasma membranes. A two-way relationship exists between soil characteristics and allelochemicals. The level of phytotoxicity is not affected only by a single soil characteristic, but they are closely linked to each other and exert a multiple-effect on retention, transport and transformation processes of allelochemicals in soil. Further efforts are needed to better understand the interactions involved in soil allelopathy and to create new opportunities for a sustainable control of agroecosystems.

This research investigated the Eucalyptus cinerea leaves efficiency in the Agrobacterium tumefaciens biocontrol, the causative agent of crown gall. GC-MS analysis of the essential oil (EO) showed that the main components were 1,8-cineole (61%) and camphene (15.13%). Thanks to its polyphenols, flavonoids, quinones, terpenoids, alkaloids, and tannins richness, the EtOAc-F exhibited the most potent antibacterial activity in vitro. Indeed, compared to the other fractions, it has the lowest MIC and MBC values of 0.312 mg/mL and 2.5 mg/mL, respectively. The GC-MS analysis of EtOAc-F confirmed its richness in antibacterial compounds including gallic acid (7.18%), shikimic acid (5.07%), and catechin (3.12%). The time-kill curve assay of EtOAc-F (2.5 mg/mL) showed a potent bactericidal effect after 20 min of direct contact with A. tumefaciens. In planta experiments, gall weights were significantly reduced when EtOAc-F was applied at 0.625 and 2.5 mg/wounds. Besides, the disease reduction rates in gall weight were 95% and 97.5%, respectively. Interestingly, no phytotoxic effect was observed since tomato seeds germinated in the presence of the different concentrations of EtOAc-F. These results suggest that EtOAc-F has a good potential to be a curative biocontrol agent for crown gall disease.

Eragrostis plana is an invasive plant in horticulture that is extremely difficult to control. The use of chemical herbicides causes weed resistance and contamination of crops. Therefore, leaf extracts obtained from E. camaldulensis, C. barbatus, and L. leucocephala were evaluated in the control of this weed. The extracts were obtained from leaves by infusion, pressurized liquid extraction, and ultrasound-assisted extraction using water or ethanol as solvents, which are green methods. The phytochemicals from E. camaldulensis and C. barbatus reduced the germination and growth of the weed, reaching up to 97% inhibition of germination, 52% reduction in shoot length, and 46% reduction in root length for the germinated seeds.

Pyranine labeled polymer nanoparticles as fluorescent markers for cell wall staining and imaging of movement within apoplast

Weed infestation is a major constraint to crop production, especially in vegetables such as cucumber and pepper, where Setaria verticillata L.P.Beauv., Phragmites communis Trin., and Cynodon dactylon L. Pers cause severe yield losses. This study evaluated the phytotoxic potential of Ficus carica L. leaves. Aqueous extracts were tested using foliar spray and soil incorporation to assess effects on seed germination and early growth of weeds and crops. The extracts exhibited strong dose-dependent inhibition, reducing germination by 46% in S. verticillata and 63.1% in C. dactylon. Root growth was suppressed by 92.1%, 89.3%, and 80.4% in C. dactylon, S. verticillata, and P. communis, respectively. Foliar spray caused the strongest inhibition, with shoot, root lengths, and leaf number reduced by up to 100% in S. verticillata L. For crop species, only a slight, nonsignificant effect was observed, confirming the selectivity of F. carica extracts in suppressing weeds while minimally affecting crops. Molecular docking revealed strong interactions between major F. carica polyphenols (1,3-di-O-caffeoylquinic acid and luteolin) and GST/HPPD enzymes, suggesting a potential mode of action. These findings highlight F. carica leaves as a bioherbicidal resource and a sustainable alternative for weed management in agriculture.