Plant and Soil最新文献

Aims

Plant diversity loss is increasingly recognized to affect ecological functions such as primary productivity and nutrient cycling, yet how the diversity of organic materials derived from plant litter influences soil microbial processes is largely unclear.

Methods

A laboratory microcosm experiment was conducted to explore the effects of litter species diversity on soil enzyme activity and microbial community in a Mongolian pine (Pinus sylvestris var. mongolica) plantation of Northeast China in 2018. Leaf litter of Mongolian pine was decomposed with the senesced aboveground materials of three dominant understory species in all possible combinations.

Results

The decomposition of mixed-species litter showed more cases of antagonistic effects on the activities of soil acid phosphomonoesterase, N-acetyl-β-D-glucosaminidase and β-glucosidase and the amount of fungal PLFAs, and synergistic effects on soil cellulase activity, the ratio of Gram-positive to Gram-negative bacteria, and the amount of actinomycetes PLFAs. Litter species composition had significant non-additive influence on soil enzyme activities and microbial community composition. According to the results of constrained redundancy analyses, litter chemical composition was significantly correlated with soil enzyme activities and microbial community composition, while the chemical diversity and stoichiometric dissimilarity had no significant effects on soil enzyme activity.

Conclusions

Our results indicate that the non-additive decomposition effects of mixed-species litter on soil enzyme activities and microbial community composition depended primarily on litter species composition, which is partly explained by litter chemical composition rather than litter chemical diversity and stoichiometric dissimilarity. Our findings highlight the intricate legacy effects of species loss on soil microbial processes.

Background and aims

Intercropping is an effective practice for increasing crop diversity and achieving sustainable agricultural development, especially in areas with limited agricultural land. Although the nitrogen turnover and trade-off responses of plant–soil systems to intercropping have been extensively studied, quantitative information on the association between P and crop productivity is lacking. Therefore, in this study, we aimed to elucidate the effects of intercropping on plant P concentration, uptake, and use efficiency and soil P availability.

Methods

We conducted a quantitative meta-analysis using a database containing 453 comparisons from 56 peer-reviewed studies.

Results

Intercropping significantly increased the soil available P concentration and phosphatase activity by 14.68% and 11.74%, respectively, compared with monocropping. However, the effects of intercropping on other P characteristics and grain yield were not significant. Among the evaluated influencing factors, crop type (cereal or legume) had the greatest effect on soil P availability, followed by soil pH and P fertilizer input. Regression analysis revealed that plant P concentration and uptake were significantly and linearly correlated with soil available P concentration and phosphatase activity. Notably, in maize–legume intercropping systems, maize exhibited increased P concentration and uptake and increased grain yield, whereas legumes exhibited constrained growth.

Conclusion

Overall, we determined that intercropping improves soil P availability, depending on the ecological environment, nutrient management, and intercropping system. This study serves as a valuable reference for effective P fertilizer input in cereal–legume intercropping systems under different management practices.

Introduction

Identifying mechanisms with potential to increase crop performance under limited water availability is critical to the future of agriculture. Many plant traits (stomatal behavior, specific leaf area, xylem architecture, ROS scavenging, root allocation, and increased osmotic potential) may enable crops to avoid or tolerate water limitation. Additionally, there is evidence that increased nitrogen (N) availability can ameliorate the negative effects of water limitation, although the mechanisms driving this effect are unclear. Here we seek to identify and synthesize the diverse plant physiological mechanisms by which increased N availability may improve plant performance under water limitation. We present four primary plant functional areas in which increased N availability has the potential to offset the negative impacts of water limitation: 1. Belowground resource acquisition, 2. Osmotic adjustment, 3. Photoprotective mechanisms, and 4. Regulation of water and light utilization.

Methods

We synthesized the diverse literature with variable N and water treatments for three important grain crop species: Zea mays, Triticum aestivum, and Oryza sativa. N treatments were standardized to ppm and normalized by soil water holding capacity, background soil N concentrations and number of fertilizer applications.

Results

Ultimately, we conclude that moderate N availability may improve plant yield under water limitation via mechanisms from all four plant functional areas, but high levels of N availability can also be detrimental to plant responses to water limitations.

Discussion

We provide recommendations for specific traits to measure in future field studies, as well as caveats to consider N species, N levels, and timing of N application in such studies.

Background and aims

Leymus chinensis is a promising grass species for restoring saline alkali grasslands, and its salt tolerance can be improved after inoculation with AMF. However, it is still unknown whether AMF can help plant adapt to saline stress by regulating plant associated microbiome of L. chinensis.

Methods

Pot experiments were conducted to investigate the effects of Rhizophagus intraradices on the growth of L. chinensis in natural saline soil through determining physicochemical indicators included biomass, ion concentration, physiological characteristics, rhizosphere soil properties and bacterial communities in the rhizosphere, root and shoot endosphere.

Results

The results demonstrated that R. intraradices significantly increased the biomass of L. chinensis and had a positive impact on ion absorption balance and physiological regulation. More importantly, the beneficial bacteria within rhizosphere, root and shoot endosphere were enriched. The microbial interaction networks in the rhizosphere, root and shoot endosphere became more complex and modular, with the changes of keystone taxa. Moreover, the correlation between microbial and plant biomass indicators has been strengthened. Microbial interaction networks had more effect than microbial diversity in promoting plant growth. Compared with the rhizosphere and shoot endosphere bacteria, the root endosphere bacteria regulated by AMF plays a greater role in improving biomass of L. chinensis.

Conclusion

Bacterial interaction patterns in the rhizosphere, root and shoot endosphere contribute to the growth of L. chinensis with AMF inoculation. Root bacterial community regulated by AMF play an important role in L. chinensis resistance to salinity.

Graphical Abstract

Background and aims

Previous studies have focused on the differing response patterns of leaf functional traits (LFTs) to nitrogen (N) addition under spatiotemporal or species classification variations. However, in N-rich forest ecosystems, it remains unclear whether continuous N input regulates the sensitivity of various plant types in different seasons to simulated N deposition.

Methods

We examined how N addition at 0, 20 (LN), and 40 kg N hm^–2 a^–1 (HN) affected the variations in LFTs and trait-trait covariations among seasons (April and August) and plant types in a N-rich evergreen broadleaf forest in western China.

Results

Along the vertical vegetation gradient within the forest, LFTs that exhibit significant seasonal variations are most prevalent in trees, followed by shrubs, while they are rare in herbs. Most plants had higher C and P concentration in August than in April. The HN treatment reduced the seasonal variation in C concentration of trees and herbs, while it accentuated that of shrubs. Additionally, HN significantly decreased the differences in C and P between trees and both shrubs and herbs, while enhancing the differences in leaf N between shrubs and herbs in August. Only the scaling exponent of the N-P allometric function (i.e., the major regression slope of (logLNC = α logLPC + logβ)) decreased with increasing N addition.

Conclusion

Various ecological adaptation strategies and environmental sensitivities among plant types resulted in heterogeneous responses of plants to N addition. Meanwhile, continuous N input enhancing (weakening) the differences in certain leaf traits among species and across seasons.

Background and aims

Understanding the eco-evolutionary processes that govern leaf elemental composition in subtropical regions with diverse forest landscapes remains a challenge. Here, we investigated the phylogenetic and environmental regulation of leaf elemental composition in subtropical forests.

Methods

We sampled surface soils and leaves from herbs, ferns, deciduous woody species, and evergreen woody species across four forest landscapes (montane, valley, karst, and island forests) in the subtropical Lijiang River basin. We used phylogenetic comparative methods to identify regulators of leaf elemental composition.

Results

Leaf elemental concentrations varied significantly among growth forms, with evergreen woody species presenting the highest leaf C concentration relative to N, P, and K. Apart from C, leaf elemental concentrations also showed significant variations across forest landscapes; for instance, karst forest species exhibited the highest leaf Ca and Mg concentrations but the lowest leaf P concentration, reflecting pronounced P deficiency and enhanced supply of Ca and Mg. Phylogenetic signal, indicating phylogenetic conservatism, was significantly detected in leaf C, K, Ca, and Mg concentrations. Evolutionary model comparisons suggested that stabilizing selection towards multiple optima for growth forms best explained variation in leaf C concentration, while stabilizing selection towards multiple optima for each growth form within a specific landscape emerged as the dominant process for leaf N, P, K, Ca, and Mg concentrations.

Conclusions

Our study highlights the critical roles of leaf elemental conservatism and stabilizing selection towards multiple optima for growth forms within and across forest landscapes in regulating leaf elemental composition in subtropical region.

Aims

This study investigates the complex interactions between urban trees and expansive clay soils, focusing on two prevalent species (Corymbia maculata and Lophostemon confertus) in Melbourne’s urban landscape. Limited field data and understanding of species-specific water use necessitate this research. We aim to quantify the spatiotemporal variability in soil-plant-water interactions within the urban contexts, a crucial factor for informed green infrastructure planning and sustainable ecosystem management in metropolitan areas.

Methods

Comprehensive field measurements were conducted over 12 months, including soil movement, soil water dynamics, tree transpiration, and leaf water potential. Sap flow sensors monitored tree water requirements. Laboratory soil testing determined soil properties and developed soil suction and water content profiles. The intercorrelation between soil water dynamics and tree water use was investigated.

Results

Peak water use for both trees occurred during summer, contributing 32–40% of their total consumption. C. maculata transpired 48.1 kL, exceeding L. confertus by 106%. The trees’ desiccation influence extended horizontally to 0.4–0.5 times the tree height and vertically to 2.3–3.3 m depth. Soil water content explained 31–36% of soil movement variability, with a strong correlation (R² > 0.9) between soil suction and water content within the active root zone.

Conclusions

This study enhances our mechanistic understanding of urban tree-soil interactions, providing valuable insights for sustainable city planning. It emphasizes species-specific considerations in tree selection and placement, especially in areas with expansive soils. The robust field data contributes to refining predictive models of soil-plant-atmosphere interactions in urban landscapes, supporting informed decision-making in urban greening initiatives.

Background and aims

In humid regions, the transpiration rate is determined by transpiration demand because of the sufficiently moist soil. However, inhibition of plant water uptake capacity due to soil waterlogging can significantly constrain the transpiration rate even after drainage. This study aimed to evaluate plant hydraulic conductance during soil waterlogging and subsequent reoxygenation and its impact on whole plant transpiration.

Methods

Two experiments were conducted to assess the ecophysiological responses of soybeans during waterlogging (Experiment 1) and reoxygenation (Experiment 2). Transpiration rate, stomatal conductance, leaf water potential, and leaf area were measured. In addition, plant hydraulic conductance was calculated using the root water uptake equation. A simple transpiration model incorporating the response of plant hydraulic conductance to waterlogging was used to evaluate the impact of waterlogging on transpiration estimation.

Results

Waterlogging for more than 3 days reduced plant hydraulic conductance, which persisted even during the post-waterlogging reoxygenation period. Furthermore, leaf water potential, stomatal conductance, and transpiration rate in waterlogging treatment exhibited a lower value than those in control during both waterlogging and reoxygenation. The constructed model effectively reproduced the responses of plant hydraulic conductance and transpiration rate, especially during reoxygenation.

Conclusion

Soil waterlogging significantly reduce the hydraulic conductance of soybean plants, resulting in leaf water stress and depression of transpiration, even during reoxygenation. Our results highlight the importance of integrating plant hydraulic responses with water dynamics models in the soil-plant-atmosphere system.

Background and aims

Plants emit exudates into the rhizosphere under environmental stresses, influencing fungal communities. The effects of reduced light, root competition, and combined stresses on root exudates and fungal regulation are unknown.

Methods

Our experiments assessed the effects of low light (L), interspecific competition (C), and combined stresses (LC) on flavonoid exudates and rhizosphere fungal communities in the roots of Juglans mandshurica and Fraxinus mandshurica. The correlation between differential exudates and fungal communities was examined.

Result

In our study, fifty-nine exudates exhibited significant changes under single and combined stresses. Under low light, eleven exudates were upregulated and ten downregulated; under interspecific competition, ten were upregulated and four downregulated; and under combined stress, two were upregulated and thirteen downregulated. Meanwhile, nine shared exudates were upregulated and one downregulated under each stress. In addition, single and combined stress affected the composition and abundance of fungal communities in the rhizosphere. Ascomycota were synergistically affected by the combined stress, while Zygomycota and Mortierella were antagonistically affected by the combined stress in Juglans mandshurica. Exudated isorhamnetin, eriodictyol, kaempferol, vicenin, and rutin showed significant positive correlations with Ascomycota, Zygomycota, Nectriaceae, Chaetomiaceae, and Mortierella. On the other hand, apigenin, hesperidin, and kaempferol showed significant negative correlations with Sordariomycetes.

Conclusion

Low light, interspecific competition, and combined stress induce changes in flavonoid exudates that may correspond to the recruitment of potentially beneficial and the inhibition of potentially harmful fungal communities, underscoring rhizosphere adaptation.

Background and aims

Cereal/legume intercropping can enhance phosphorus (P) uptake compared with monocultures. However, the mechanisms through which arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) contribute to the advantages in biomass and P uptake by cereal/legume intercropping remain elusive.

Methods

We first analyzed P cycling-related soil microbiome and the associated genes in a long-term low P (LP) and high P (HP) input field experiment. Then we conducted two mesocosm experiments by establishing with two root compartments with the planting patterns of maize monoculture and maize/faba bean intercropping. One compartment of monocultured maize and intercropped faba bean was inoculated with AMF (donor), and the suspensions of LP or HP soils or water was added to the other compartment (receiver) in experiment I to test the legacy effect of soil microbiome conditioned by different field P fertilization, and the following experiment was to detect the effect of specific organic or inorganic PSB on intercropping interactions and advantages.

Main results

The abundance and structure of total P cycling-related microbes and genes were comparable between LP and HP soils. The addition of bacterial suspensions significantly enhanced shoot biomass but not P content of receiver maize regardless of the AMF presence or not. With AMF, single inorganic PSB and the mixed inorganic and organic PSB increased the shoot biomass and P content of receiver maize than single organic PSB regardless of monocultured or intercropped receiver maize. However, only the mixed inorganic and organic PSB established intercropping advantages in shoot biomass and P content of receiver maize.

Conclusion

The hyphae from faba bean stimulate the cooperation between organic and inorganic PSB to improve the growth and P content of maize in maize/faba bean mixture. Our study emphasized that maintaining the diversity of AMF and PSB communities in soil is important for the overyielding and P uptake by intercropping.