Journal of Soil Science and Plant Nutrition最新文献

Purpose

Grapevine (Vitis vinifera L.) is a relevant crop, which is associated to arbuscular mycorrhizal fungi (AMF) that are influenced by agricultural practices. The hypothesis of this study is that organic/biodynamic management stimulates grapevine mycorrhizal colonisation and increases AMF diversity in Chilean vineyards. The aim of this study was to determine the influence of agricultural management on AMF association and AMF diversity in Chilean vineyards.

Methods

Mycorrhizal colonisation of grapevine roots from organic/biodynamic and conventional vineyards in Northern (Elqui Valley), Central (Casablanca and Cachapoal Valleys), and Southern Chile (Maule and Itata Valleys), was determined under a microscope. AMF diversity was analysed by morphological, and molecular characterisation of spores through SSU-ITS-LSU rRNA region sequence analyses.

Results

AMF colonisation of grapevine roots was influenced by vineyard management independent of the season. Higher mycorrhizal colonisation was detected in organic/biodynamic grapevine soils (20 − 35%), compared with conventional soils (6 − 31%). Twelve AMF species were identified in vineyards, belonging to five Glomeromycota families. Interestingly, organic/biodynamic vineyards showed higher AMF diversity. The three predominant morphotypes were Funneliformis verruculosum (GL1), Septoglomus sp. (GL4) and Septoglomus constrictum (GL5). Molecular analyses of AMF spores highlighted the occurrence of Septoglomus, Acaulospora, Pacispora and Cetraspora genera in vineyards.

Conclusions

In this study, AMF diversity in Chilean vineyards is described for the first time. The diversity of AMF in vineyards in Chile was higher than the diversity reported in other wine-producing ecosystems. The understanding of agricultural practices on AMF activity and diversity may be crucial to improve the vineyard management.

Rocket salads (Diplotaxis spp. and Eruca spp.) are leafy vegetables appreciated for their typical taste and nutritional value. When exposed to salt stress, these plants undergo morpho-physiological and metabolic changes. The aim of the study was to investigate the efficacy of a “root-promoting biostimulant” (Radifarm^®) applied during germination (Experiment 1) and during the growth cycle (Experiment 2) on two rocket species under salt stress. Experiment 1 explored if Radifarm^® can protect seed from salt stress in early-stage development. Different salt levels (0, 150 and 200 mM NaCl) were combined with different Radifarm^® concentrations (0, 0.5, 1, 2.5, 5 mL L^− 1). Experiment 2 investigated how Radifarm^® can promote plant growth after transplantation when irrigated with saline water (0, 150, and 200 mM NaCl) until harvest. Experiment 1 showed that salt stress significantly affected the germination of rocket salads. The addition of Radifarm^® did not improve the germination of D. tenuifolia grown under any salt conditions, but it was beneficial for E. sativa when the highest level of Radifarm^® was applied. In Experiment 2, the application of Radifarm^® significantly reduced the symptoms of salt stress in both species. In E. sativa, salt stress affected all growth parameters (plant height, leaf number and area). However, under 200 mM NaCl, plants fully recovered when Radifarm^® was applied. The same recovery was observed for chlorophyll content in both species. Radifarm^® also contributed to increase protein and lipid content compared to plants under salt stress. This study showed that Radifarm^® was able to protect both species from salt stress.

Purpose: Soil aggregate stability is a crucial property affecting soil erodibility, water infiltration and carbon sequestration. This study aimed to determine ultrasonic aggregate stability (USAS) as well as solid and dissolved organic carbon (OC and DOC) associated with aggregate fractions of different aggregation strength and size in volcanic soils along an Andosol-Luvisol-Cambisol chronosequence on the Galápagos Islands. Methods: Aggregate stability was determined by ultrasonication at different energy levels, i.e. 20, 100, and 500 J mL^− 1. OC was measured in different aggregate size fractions, i.e. macroaggregates (250–2000 μm), microaggregates (63–250 μm), and the fraction < 63 μm, and released DOC was determined. Results: Aggregate breakdown increased with ultrasonic energy input. The Andosol (short-range order minerals, high OC) had the highest aggregate stability among the studied soils. The OC contents in the stable macro- and microaggregates (at 20 J mL^− 1) were highest in the Andosol (20.4 and 20.1%, respectively), followed by the Luvisol (11.6 and 10.8%, respectively) and the Cambisol (6.5 and 6.7%, respectively). The decreasing aggregate-associated OC stabilization with increasing soil age coincided with mineralogical changes from short-range order phases to high-activity clays to low-activity clays. The release of DOC during sonication was highest for the intermediate-aged soil (Luvisol) and mainly occurred at low and intermediate energy levels, while for the young soil (Andosol), released DOC steadily increased until the highest energy level. Conclusions: Our results imply that mineralogical/pedogenic changes over millennial time scales can make volcanic soils more susceptible to losses of OC by leaching and water erosion.

Purpose

Biofertilizer application in the agriculture industries is deemed sustainable in the long run given its ability to restore fertility of soil and increase crops productivity through several direct and indirect mechanisms. However, the dissolved fraction (DOM), which is made up of tiny molecules of plant and microbial origin produced by lysed cells and released metabolites as influenced directly through biofertilizer amendment is unknown.

Methods

An untargeted metabolomics profiling was conducted via an in vitro rhizospheric Bungor soil series incubation with IBG Biofertilizer from IBG Manufacturing Sdn Bhd. In this study, a comparative analysis between Ultisols samples inoculated with IBG biofertilizer and control samples was conducted under simulated humid tropic conditions.

Results

18 mass-to-charge ratio (m/z) values with VIP (Variable Importance in Projection) scores exceeding 1 in the IBG biofertilizer-inoculated Ultisol. The annotated metabolites primarily consisted of endogenous compounds, including amino acids, organic acids, nucleic acids, fatty acids, and amines. Notably, a signaling compound, homoserine lactone (m/z 270), exhibited the highest fold changes in response to IBG biofertilizer inoculation on the simulated Ultisol. Furthermore, key metabolic pathways such as Glycerophospholipid metabolism, Glycine, serine, and threonine metabolism, Cysteine and methionine metabolism, and Alanine, aspartate, and glutamate metabolism were notably affected by IBG biofertilizer inoculation on the simulated soil model.

Conclusions

These findings emphasized the metabolic responses induced by IBG biofertilizer in Ultisols under the simulated humid tropic conditions., which suggests that biofertilizers application have some significant changes on soil metabolites that overall soil productivity could be affected by these potential biomarkers. Understanding these metabolic shifts not only enhances crop productivity but also addresses broader questions of soil health and ecosystem sustainability in the face of climate change and agricultural intensification.

Ammonia-oxidizing archaea (AOA) and Ammonia-oxidizing bacteria (AOB) are key microorganisms in the soil nitrogen cycle, but how they change in the intercropping system, affected by interspecific interaction and N application levels, is not clear. A field experiment of soybean/maize intercropping with three nitrogen application levels was designed. Illumina MiSeq sequencing was used to determine AOA and AOB diversity and communities in the rhizosphere of intercropped soybean and maize. Nitrogen absorption of maize grain has increased by 21.09% to 33.54% in intercropping compared with monoculture, while that of soybean was reduced, especially in 240 kg N·ha⁻¹(N2). Our results showed that the α-diversity of AOA and AOB in the rhizosphere of maize was reduced in intercropping treatment across all N application levels. The opposite results were found in intercropped soybeans. Additionally, there was an increase in the α-diversity of AOB in the soybean rhizosphere with N2 treatments. Specifically, α-diversity of AOB in intercropped soybean in 240 kg N·ha⁻¹(N2) increased by 10.45% and 1.6% relative to the 0 kg N·ha⁻¹(N0) and 180 kg N·ha⁻¹(N1), respectively. This effect is further magnified within the monocropped maize under 240 kg N·ha⁻¹(N2), reflecting enhancements of 10.68% and 5.37%, respectively. Under intercropping conditions, the abundance of the dominant AOA genus, Nitrososphaera, significantly decreased more than sixfold under 180 kg N·ha⁻¹(N1). Conversely, the abundance of the dominant AOB genus, Nitrosospira, increases with the higher nitrogen application rates, although intercropping exerts a diminishing influence. While its trend within the rhizosphere of soybean is the opposite. Moreover, Redundancy Analysis (RDA) and Mantel tests showed a correlation between variations in ammonia-oxidizing microbial communities and soil-available nitrogen content (p = 0.001, r > 0.4). Due to species competition after intercropping, the soil available nitrogen content decreased, resulting in changes in the soil ammonia-oxidizing microbial community. The results indicated that interspecific competition in intercropping systems could change the diversity and composition of AOA and AOB in the rhizosphere of crops, consequently influencing N transformation and enhancing nitrogen uptake. These findings elucidated the mechanisms of how intercropping systems bolster nitrogen-use efficiency through the dynamics of rhizosphere microorganisms.

The application of mineral-solubilizing microbial inoculums is a biological strategy used for the restoration of vegetation at rock mining sites. These inoculums improve soil fertility, enhance plant growth, and accelerate soil weathering. However, their impacts on rhizospheric soil microbial communities are not well understood. This study aimed to elucidate how various mineral-solubilizing microbial inoculums affected the root systems of R. pseudoacacia. A pot experiment was conducted, and 32 samples were extracted from four different mineral-solubilizing microbial inoculum treatments to investigate the responses of soil bacterial and fungal communities in the rhizospheres of R. pseudoacacia. The results showed that the impacts of the inoculums on fungal community structures surpassed those of the bacterial communities. The relative abundance of Proteobacteria increased, which was strongly correlated with root nodulation. Interestingly, the inoculums significantly influenced the diversity and evenness of bacterial communities in the rhizospheric soil. Correlation analysis revealed positive correlations between Proteobacteria, Verrucomicrobia, Ascomycota, Zoopagomycota, soil enzyme activities, and plant growth. RDA analysis indicated that the relative abundance of these bacterial and fungal phyla positively influenced root nodulation. This study suggests that the application of mineral-solubilizing microbial inoculums optimizes the rhizospheric soil microbial community structure, promotes R. pseudoacacia root nodulation, and enhance the nitrogen fixation capacities of plants. Further, it provides a theoretical foundation for the application of mineral-solubilizing microbial inoculums for slope ecological restoration.

The addition of organic materials to the fertilization regime can be instrumental in reducing the amount of chemical fertilizers use, while maintain optimum nutrient status in the trees. The 2 year field experiment was conducted to evaluate the effect of different nutrient source combination in comparison to conventional recommendation on growth, fruit yield and leaf nutrient status of plum cv. ‘Black Amber’ grown in hills of Himachal Pradesh, India. Treatments included conventional fertilizers rate which are recommended to the farmer (NPK₁₀₀) compared with 10 treatment combinations with reduced rate of chemical fertilizer (NPK₈₀; NPK₇₀; NPK₆₀), organic manure (Farmyardmanure; Vermicompost) and microbial formulations (Biofertilizers; Jeevamrit). Data revealed that NPK₇₀ + 10% RDN through vermicompost + biofertilizer (T-6) and NPK₇₀ + 10% RDN through vermicompost + jeevamrit (T-7) yielded the best results in terms of shoot growth, leaf area, leaf chlorophyll content, photosynthesis rate, stomatal conductance and transpiration rate in both the years. Cumulative fruit yield peaked in T-7 by 6% over conventional rate NPK₁₀₀ (T-1); there were no difference in fruit yield between T-6 and T-7. Integrated fertilizers combination registered significant influence on the leaf nutritional status, but not consistent. The deviation from optimum (DOP) index revealed excess of leaf phosphorus and iron content with all the treatments application, while negative for other elements however, T-6 maintained a better nutrient status than other treatments. The treatment combinations T-6 and T-7 can be recommended to the farmers for maintaining nutrient balance, thereby ensuring sustaining crop production in subsequent years.

The intensive and repeated use of chemical herbicides has led to the emergence of herbicide-resistant weeds, which, in addition to their environmental impacts, also pose significant threats to human and animal health. This study aimed to explore the potential of oilseed industrial wastes, specifically soybean and flaxseed meals, as safe and environmentally friendly bioherbicides for controlling weeds associated with onion crops. Two field experiments were conducted along two successive winter of 2020/21 and 2021/22. Treatments involved foliar spray of soybean and flaxseed meals in three different concentrations (15, 30 and 45%), mulching of seed meals, oxyfluorfen herbicide, two hand hoeing and untreated weedy check. The findings demonstrated that all weed control treatments significantly reduced weed density, biomass and nutrient uptake. Two hand hoeing, oxyfluorfen herbicide and the mulching of soybean and flaxseed meals alternated in the top rank for weed control, showing minimal significant differences among them. Following these effective treatments, soybean meal extracts at 45 and 30% exhibited notable weed control compared to the weedy check. The greatest enhancement in onion growth, yield characteristics and bulb quality was observed with the application of hand hoeing, soybean and flaxseed meal mulching treatments, with no significant differences between them. High-Performance Liquid Chromatography (HPLC) fractionation of both meals identified various phenolic acids at different concentrations. Practically, these safe efficient treatments proved progress on chemical herbicide. Hence, onion farmers are advised to apply soybean and flaxseed meals mulching safe treatments as alternative to harmful chemical herbicides under all experimental conditions.

Using the transgenic approach, the current study investigated the tripartite interaction of miRNA166, Plant Growth Promoting Rhizobacteria (PGPR), and chickpea crops in response to drought. miR166, an evolutionarily conserved small RNA, was cloned and transformed in a homologous manner. This Car-miR166 is reported in our previous research to have drought-enduring roles in response to microbial candidates. A Pseudomonas putida strain RA (MTCC5279) is used as a PGPR for the whole study. The overexpressed lines generated using tissue-culture practice were functionally validated with physiological parameters studied using Li-Cor 6400XT, including photosynthesis rate, transpiration rate, water-use efficiency, and electron transport rate. We also studied the relative water content of the overexpressed lines in comparison to treated control plants. In biochemical methods, we studied the accumulation of proline, superoxide dismutase, peroxidase, catalase, H₂O₂ and lipid peroxidation levels. miR166 has its target as ATHB15 (Homeobox-leucine zipper protein-15) validated using 5’ RNA Ligase-Mediated Rapid Amplification of cDNA Ends (RLM-RACE) experiment. At the molecular levels, we carried out the stem-loop quantitative real-time (qRT) PCR analysis of miR166 and the expression analysis of ATHB15 in transgenic lines. As per our study, the results reported that the transgenic lines showed a positive interaction of miR166 with PGPR, resulting in drought stress mitigation and better plant survival in harsh drought conditions. In conclusion, the physiology, biochemistry, and molecular expression levels of Car-miR166 (Cicer arietinum L.) in transgenic lines in response to PGPR support enhanced growth and development in response to PGPR in transgenic lines under drought.

Water deficit impacts plant growth and development, causing physiological disturbances that trigger oxidative stress. As an alternative, exogenous application of a sort of molecule can minimize these damages and reduce productivity losses. The iodine (I) supplementation has shown considerable benefits to stressed plants. Nevertheless, there are no results about I mitigating the water deficit stress in coffee plants. Coffee plants were grown in 10-L pots arranged wholly randomized. Four doses of potassium iodate (KIO₃) were tested: 0.0, 2.5, 5.0, and 10.0 mg dm⁻³ of soil, then the plants were subjected to water deficit and compared to treatments with no KIO₃ and water deficit (Control). The water deficit damaged biomass and relative growth of the coffee plant. However, the application of 2.5 mg dm⁻³ of KIO₃ attenuated some symptoms, increasing: photosynthetic efficiency, relative water content, water deficit tolerance index, content of photosynthetic pigments, and compatible osmolytes. In addition, we observed the stimulation of the antioxidant enzymatic system, allowing higher cell membrane stability. Doses of 5.0 and 10.0 mg dm⁻³ of KIO₃, in spite of induced higher activation of the antioxidant system it was observed a possible toxicity effect due to excess KIO₃. The application of 2.5 mg dm⁻³ KIO₃ via soil can modulate metabolic and biochemical processes, allowing an improvement in the growth and development of coffee plants subjected to water deficit, suggesting that it could serve as a viable strategy for managing coffee plants under drought conditions.