Plant and Soil最新文献

Aim

The unregulated use of rare earth elements, such as Europium (Eu), may result in their build-up in soils. Here, we investigated how Eu affects wheat growth, photosynthesis, and redox homeostasis and how Arbuscular mycorrhizal fungi (AMF) may influence these processes.

Methods

The wheat plants were grown in soil with 1.09 mmol Eu^3+/kg and/or AMF inoculation. The study is mainly based on a comprehensive examination of the detailed biochemical and metabolic mechanisms underlying the Eu stress mitigating impact of Eu by AMF in wheat plants.

Results

Soil contamination with Eu significantly induced a reduction in biomass accumulation and photosynthesis-related parameters, including photosynthetic rate (61%) and chlorophyll content (24.6%). On the other hand, AMF could counteract Eu’s induced growth and photosynthesis inhibition. Under Eu stress, AMF colonization significantly increased fresh and dry weights by 43% and 23.5%, respectively, compared to Eu treatment. AMF colonization also induced minerals (e.g., Ca, K, Zn, and N) uptake under control and Eu stress conditions. By bolstering the antioxidant defense mechanisms, such as ROS-scavenging metabolites (flavonoids and polyphenols), AMF mitigated Eu-induced oxidative damage. In terms of the primary metabolites, organic acids, essential amino acids, and unsaturated fatty acids were increased by AMF colonization, particularly under Eu stress conditions.

Conclusion

Applying AMF is a workable approach for reducing Eu toxicity in wheat plants.

Aims

Rotational Impoundment Management (RIM) involves summer inundation of impounded mangrove forests for mosquito management. The goal of this study was to investigate the impact of RIM on communities of aerobic ammonia-oxidizing microorganisms in Avicennia germinans dominated mangrove forest soils.

Methods

Soil samples were collected annually in a managed and an adjacent, non-managed impoundment before and after the start of RIM at three elevation levels with their characteristic mangrove habitats, i.e., dwarf (highest elevation), sparse and dense (lowest elevation). The ammonia-oxidizing communities were studied by qPCR and amplicon analyses based on thaumarchaeal and betaproteobacterial amoA genes.

Results

Temporal variations in copy numbers and assemblies of amoA gene amplicons were limited. Thaumarchaeal amoA genes increased in the dwarf and sparse habitat in the non-managed impoundment, and betaproteobacterial amoA genes increased in the dwarf habitat in the RIM impoundment. No copies of the amoA gene of Nitrospirota (comammox bacteria) were detected in either impoundment. Whereas there were no significant effects of RIM on the composition of thaumarchaeal communities, RIM affected the composition of betaproteobacterial amoA assemblies in all habitats in the RIM impoundment.

Conclusions

Direct consequences of RIM were reflected in changes in the composition of assemblies of amplicon sequence variants (ASVs) of ammonia-oxidizing Betaproteobacteria in all mangrove habitats of the RIM impoundment. Significant temporal changes at higher elevations in the non-managed impoundment were likely due to groundwater exchange between the impoundments.

Background

Gypsum is a valuable resource for farmers, supplying essential calcium and sulfur for plant growth. It serves as a crucial soil amendment, particularly in reclaiming alkali and sodic soils. While not a liming material, gypsum is widely recognized as a nutrient source for calcium and sulfur in acidic soils. The presence of calcium in various crops growing in acidic soils is instrumental in alleviating aluminum toxicity and mitigating aluminum phytotoxicity.

Scope

The application of gypsum positively influences nutrient uptake, thereby enhancing their availability and overall productivity in acidic soils. Synthetic gypsum variants like slag-based gypsum, phosphogypsum, and flue gas desulfurized gypsum have garnered attention due to their elevated silicon content, which enhances plant accessibility in acidic soils. Crucially, gypsum does not significantly alter the pH of acidic soils, although it may induce slight changes depending on specific soil conditions such as mineral composition and cation exchange capacity.

Conclusion

Gypsum promotes improved root development in crops, exerting a multifaceted impact on soil physicochemical properties, ultimately bolstering crop productivity and the sustainability of acidic soils. Furthermore, gypsum contributes to mitigating greenhouse gas emissions in acidic soils, particularly in reducing methane emissions. The recent application of industrial gypsum has emerged as a viable strategy for enhancing the immobilization of heavymetals in acidic soils. These versatile applications underscore the potential benefits of gypsum for the sustainable management and utilization of acidic soils.

Background and aims

Plant endophytes assist in plant adaptation to adverse conditions by altering the host plant’s physiology and regulating the rhizosphere microenvironment. As one of the important members of soil biosphere, nematodes play an important role in soil element cycling and physical structure. However, it is still unclear whether soil nematodes were associated with endophyte-mediated adaptations of host plants to an unfavorable environment.

Methods

The rhizosphere nematode communities were analyzed after inoculating a fungal endophyte, Phomopsis liquidambaris, under continuous monocropping conditions with high-throughput sequencing. Nematode chemotaxis experiments were carried out to verify the effect of Ph. liquidambaris-induced root exudates on nematode movement behavior. Root defence enzyme activities and plant growth parameters were analysed after introducing Ph. liquidambaris-enriched nematode communities to the rhizosphere under continuous monocropping conditions.

Results

Ph. liquidambaris increased peanut growth under continuous cropping conditions. Ph. liquidambaris inoculation changed the composition of rhizosphere nematode communities by regulating root exudates, which led to an increase in free-living nematodes and a reduction in plant parasitic nematodes, Mesocriconema, at different periods of plant developmental stages. The application of the insecticide abamectin, which is similar to endophyte fungal treatment, decreased nematode populations and diversity. In addition, a nematode transplant experiment revealed that the soil nematodes induced by Ph. liquidambaris inoculation led to a rise in peanut root defence enzyme activities to improve plant growth under continuous monocropping conditions.

Conclusion

Peanut inoculated with endophyte fungi can increase plant fitness by changing the soil nematode community through root exudates under continuous monocropping conditions.

Background and aims

Grassland ecosystems across the globe are increasingly threatened by climate change, which is predicted to exert different pressures on native and invasive plants. Plant responses to changing environmental conditions are often measured or predicted using their morphological and anatomical traits, however, few studies account for the intraspecific trait plasticity that plants exhibit in response to environmental stressors, including drought. In this study, we examine whether a six-year experimentally induced drought altered plant species composition and diversity in a grassland in western Manitoba, Canada, and whether smooth brome (Bromus inermis Leyss.), an invasive perennial grass, exhibited differential root morphology and architecture as a result of drought.

Methods

We conducted a plant inventory, harvested aboveground plant biomass, and collected, washed, and scanned roots of smooth brome individuals sampled from a long-term, extreme drought experiment. Scanned images of the roots of twenty smooth brome individuals were analyzed to compare the morphological and architectural traits, including the proportion of rhizomes produced from root crowns, in plants growing in drought and ambient conditions.

Results

Long-term drought increased the alpha diversity but not the beta diversity of experimental grasslands. For smooth brome, drought increased the number of crown buds that produced rhizomes, and the total length and surface area of roots. Smooth brome also increased its allocation of root length and surface area to very fine roots under drought.

Conclusion

Smooth brome exhibited significant differences in morphological root traits following drought, indicating a phenotypically plastic strategy of water acquisition. Our work reinforces the importance of incorporating intraspecific variation in root traits into measurements of plant responses to drought stress. Understanding how plants respond to drought is critical to predicting how climate change will continue to impact the composition and diversity of grasslands across North America, including the spread of exotic invasive species.

Aims

Soil salinization poses a significant challenge to agriculture. The practice of returning straw to the field has garnered increasing attention as a sustainable method to improve salinized land. This study aimed to investigate the impact of nitrogen application rates on rice straw decomposition, rice straw nutrient release, and rice yield in saline sodic rice field conditions.

Methods

The field experiment was designed with five nitrogen (N) fertilizer rates with 0 (N0), 90 (N1), 180 (N2), 270 (N3), and 360 kg N ha⁻¹ (N4) under the condition of full return (8 t ha⁻¹) of straw from sodic-saline paddy fields, nylon mesh bag filling method was used to study the decomposition process of rice straw. The field experiment was conducted in a completely randomized design with three replications.

Results

The results showed that the application of N fertilizer promoted the decomposition of rice straw and the release of C, N and P from the straw, but had no effect on the release of K from the straw. Compared with N0, the cumulative decomposition rates of rice straw in N1, N2, N3 and N4 treatments were significantly increased by 10.05%, 15.10%, 20.00% and 18.44%, respectively (two-year average). In addition, the highest rice yield was obtained in the N3 treatment.

Conclusion

Overall, the study suggests that applying 270 kg N ha⁻¹ is the most effective in promoting rice straw decomposition, nutrient release, and increasing rice yield in sodic saline rice fields, offering valuable insights for optimizing N fertilizer application and maximizing farmer’s economic benefits.

Aim

Symbiotic interactions between roots and mycorrhiza drive plant coexistence, yet the roles of the common mycorrhizal network (CMNs) between plant species remain poorly understood.

Methods

We conducted a compartmented microcosm experiment to assess AMF effects on the coexistence of mixed legumes (Medicago sativa or Trifolium repens) with grasses (Dactylis glomerata). Plant species were selected based on distinct functional characteristics such as symbiotic N₂-fixation ability, plant height, rooting depth, root diameter, and root surface area. The δ¹³C signature of AMF-specific fatty acids (C16:1ω5) in the hyphal compartment were measured to determine the carbon contribution of symbiotic plants in CMNs. Dual-labeled organic substrates (¹³C:¹⁵N) were used to assess the organic nitrogen uptake by host plants through CMNs.

Results

Plant coexistence depended on the mycorrhizal growth response (MGR) of host plants and the resource (C and N) exchange through CMNs, as plants benefit specifically from their fungal partners. MGR was closely correlated with plant functional traits. Legumes had a greater MGR than grasses, primarily due to their thicker roots and smaller root surface area. In M. sativa + D. glomerata bi-mixture, M. sativa, with a greater MGR in biomass and net photosynthetic rate, consistently invested more carbon for the fungal partners. Simultaneously, both M. sativa and D. glomerata obtained nutritional benefits from the hyphal network. Carbon allocation and nutrient acquisition were more balanced in mixtures T. repens + D. glomerata.

Conclusion

Differential MGR of host plant growth and the exchange of resources through CMNs are crucial for the coexistence of plant species in mixtures.

Graphical abstract

Background and aims

Timely and accurate knowledge of the spatiotemporal variation characteristics of soil salinization is paramount. The vegetation index (VI) time series holds significant promise in soil salinization monitoring, yet studies on using high spatiotemporal resolution remain limited. This study aimed to evaluate the effectiveness of high spatiotemporal resolution VI time series for soil salinization monitoring.

Methods

First, an optimized Gap Filling and Savitzky–Golay filtering (GF-SG) method was proposed to reconstruct high-quality Landsat NDVI time-series data. Second, three inversion models (Models A, B, and C) were established to assess the performance of the high spatiotemporal resolution VI time series in soil salinization monitoring. Model A was developed using single-temporal Landsat images, while Models B and C were developed by incorporating MODIS and high-quality Landsat NDVI time-series data, respectively. Finally, we achieved the inversion and spatiotemporal variations monitoring of soil salinization in the Yellow River Delta (YRD) based on the optimal model.

Results

The Model C demonstrated the highest prediction accuracy (R² = 0.84, RMSE = 0.64 mS cm⁻¹). The optimal model predictions show that soil salinization in the YRD gradually decreases from coastal to inland areas, with an overall improving trend from 2004 to 2022.

Conclusion

The high spatiotemporal resolution VI time series significantly improves the predictive and generalization capabilities of the model and can be effectively used for spatiotemporal dynamic monitoring of soil salinization.

Background and aims

Plant-soil feedbacks (PSFs) play an important role in mediating plant species coexistence, community dynamics and ecosystem functioning. Soil biota (e.g. mutualists, pathogens), nutrient availability and secondary chemicals can drive the strength and direction of PSFs, but the variations and context-dependence of their effects remain unclear.

Methods

We used a phylogenetically controlled meta-analysis of 57 PSF studies across 166 plant species to explore whether and how these drivers affect individual PSFs (the performance of a species on conspecific versus heterospecific soils) and pairwise PSFs (indicating whether feedbacks promote stable or unstable species coexistence) under various intrinsic, environmental and experimental contexts.

Results

Mutualists led to stronger positive individual and pairwise PSFs across various intrinsic and external contexts. However, PSFs became more negative when whole biota was present, with stronger negative effects on native species compared to exotic species and the most negative effects on plants experiencing interspecific competition. Manipulations of pathogens, nutrient availability and secondary chemicals had overall minimal influence on both types of PSFs, but the effect of nutrient availability on pairwise PSFs increased with increasing phylogenetic distance between species.

Conclusion

Our study suggests that soil biota is an important driver of PSFs and that plant origin and competitive context should be considered when predicting the role of soil biota in driving PSFs. Finally, we propose several directions for the next generation of PSF experiments towards a better understanding of the relative importance and interactions of different PSF drivers.

Background and aims

The changes in soil physical properties caused by root exudates depend largely on the chemical composition of root exudates. Our aim was to explore the effects of non-specific root exudates on the physical properties of soil change.

Methods

Five sugar compounds, five amino acid compounds, and five organic acid compounds were selected and added to loess as three single addition treatments (amino acids, organic acids, and sugars) and four combined addition treatments (amino acids + organic acids, amino acids + sugars, organic acids + sugars, and amino acids + organic acids + sugars). Soil water repellency, aggregate stability, and shear resistance tests were performed on the loess.

Results

The treatments sugars, amino acids, and amino acids + sugars significantly increased soil water repellency. In addition, organic acids + sugars maximised mean weight diameter (MWD), geometric mean diameter (GMD) and the content of > 0.25 mm water-stable aggregates (R_0.25), and minimised the percentage of aggregates destroyed (PAD) in the addition treatments. All treatments except for amino acids significantly increased soil shear strength and cohesion of the loess. Amino acids, amino acids + sugars, and amino acids + organic acids + sugars significantly increased the internal friction angle.

Conclusion

The single addition treatments had a higher effect on soil hydraulic properties, while the combined addition treatments had a higher effect on soil mechanical properties. Sugars and amino acids substantially increased soil hydraulic stability. Sugars combined with other compounds, especially with organic acids, significantly improved soil mechanical stability.