Rhizosphere Content Research Articles

Insight into the short-term effects of TiO2 nanoparticles on the cultivation of medicinal plants: Comprehensive analysis of Panax ginseng physiological indicators, soil physicochemical properties and microbiome

To meet societal needs, a large number of medicinal plants are cultivated artificially. However, issues such as diseases and continuous cropping obstacles (CCO) have severely impacted their quality and yield. Exploring and innovating the cultivation technology for medicinal plants is essential to meet their high demand and ensure sustainable development. The role of titanium dioxide nanoparticles (nano-TiO2) in medicinal plant cultivation remains unclear. To advance the application of nanotechnology in this field, a comprehensive exploration of its potential benefits is necessary. In this study, nano-TiO2 was applied to ginseng (Panax ginseng C.A. Meyer) to acquire a holistic comprehension of its impact on ginseng growth, rhizosphere, and ginseng-used soil. Our findings reveal that nano-TiO2 significantly enhances ginseng root activity and has notable effects on antioxidant enzyme systems. The two concentrations of nano-TiO2 markedly influenced the structure and composition of microbial communities in the rhizosphere and ginseng-used soil, including key microorganisms such as Chloroflexi and Acidobacteriota, which are closely involved in soil function. Furthermore, nano-TiO2 altered the competitive and cooperative relationships within microbial networks. Nano-TiO2 application significantly increased soil organic matter (SOM) content in rhizosphere and ginseng-used soils and affected the activities of several important soil enzymes. Environmental factors, such as EC, pH, and soil nutrients, were found to be the main factors influencing the microbial community. In conclusion, our findings illuminate the complex effects of nano-TiO2 on the “plant-microbial-soil” system in the context of ginseng cultivation. This work offers novel strategies for optimizing medicinal plant growth and development, as well as improving cultivated soil by using nanomaterials.

Impact of sewage sludge, nanoparticles, and clay minerals addition on cucumber growth, phosphorus uptake, soil phosphorus status, and potential risk of phosphorus loss

There is little information about the impact of sewage sludge, nanoparticles, and clay minerals on cucumber ( Cucumis sativus L.) growth and phosphorus content in different plant parts. In this study we treated a soil with different rates of sewage sludge (1%, 5%, and 10%), along with two nanoparticles (SiO 2 and nano-montmorillonite at 0 and 1%), and two clay minerals (zeolite and vermiculite at 0 and 3%). We aimed at investigating the impact of these amendments on cucumber growth, phosphorus content in root, shoot, and fruit, phosphorus content in rhizosphere and non-rhizosphere soils, and determining the impact of these amendments on the potential risk of phosphorus loss from soil. Plant growth in the soil treated with sewage sludge at 1% and 5% was higher than that at 10% sewage sludge, while the cucumber in the 10% sewage sludge plus 1% nano-montmorillonite-treated soil dried out. Phosphorus content in fruit was higher than in root and phosphorus in root was higher than that in shoot. Cucumber plant in the 10% sewage sludge treated soil had the highest amount of phosphorus compared to the other treatments, while plants in the nanoparticles and clay minerals treatments had lower content of phosphorus than the control. The highest phosphorus content was extracted from soil treated with 10% sewage sludge, while the lowest was extracted from the soil treated with nanoparticles and clay minerals. In average of all treatments, soil phosphorus extracted by water-extractable phosphorus in the rhizosphere soil was higher than phosphorus in the non-rhizosphere soil. The results indicated that calcium chloride-extractable phosphorus was more effective in predicting phosphorus uptake than water-extractable phosphorus and Olsen-extractable phosphorus. Also, the soil treated with sewage sludge at 5% and 10% would potentially increase the risk of phosphorus losses. We concluded that the soil treated with 1% sewage sludge, with or without nanoparticles or clay minerals, could provide the amount of phosphorus required for the growth of cucumber, while there was no obvious potential risk of phosphorus loss, making this treatment more beneficial for cucumber. • Cucumber growth increased in soil at 1% sewage sludge; no phosphorus loss occurred. • Highest plant phosphorus was observed in soil at 10% sewage sludge. • Correlation of root P and CaCl 2 -extracted P was highest.

Comparing microbial community heterogeneity in soil under organic and conventional agricultural system cultivated with olive and peach trees in three fields differ with age at Al-Jouf Saudi Arabia

This research study was carried out at Al-Jouf region, north eastern Saudi Arabia, to investigate the differences in microbial community and density of microorganisms in the rhizosphere of olive (Olea europaea) and peach (Prunus persica) tree fields subjected to growth under organic and conventional agriculture systems. The soil analytical processes were conducted in three olive and three peach fields (9, 17, 27 years old and 20 ha in area) under organic fertilization, and three similar olive and peach fields under conventional fertilization system. The results indicated significant variations between the two agricultural systems in rhizosphere content of microbial and mycorrhizal colonization%. The highest percentages of actinomycetes, total fungi and bacteria (PSM) were recorded in the organically agricultural system (OAS) in olive fields in comparison to conventionally agricultural system (CAS). Regarding field ages OAS dominated CAS in total number of fungi under all olive fields ages, while under peach fields fungi counts were significantly high under CAS compared to OAS. Under peach fields OAS dominated giving the highest actinomycetes and bacteria and CAS dominated by giving the highest CFU and fungi count. The significantly highest counts of CFU and bacteria were attained under conventional farming system (CAS) in all of the different aged field compared to OAS. Actinomycetes and bacteria in young fields were significantly high under CAS, while in old fields actinomycetes and fungi counts were the highest under OAS.

Arbuscular mycorrhiza, carbon content and soil aggregation in Sonoran Desert plants

Desert trees and shrubs play a relevant role in stabilizing the deserts ecosystems, and mycorrhizal association is very important for its adaptation and survival in arid and semi-arid areas. The influence of mycorrhizic fungi on the formation of water stable aggregates through glomalin and on soil carbon content has been studied. We sampled the rhizosphere of representative trees (<em>Olneya tesota</em>, <em>Prosopis juliflora,</em> and<em> Parkinsonia microphylla</em>), and shrubs (<em>Jatropha cuneata</em> and <em>Larrea tridentata</em>) of the Sonoran Desert for four seasons in order to evaluate the mycorrhizal status, carbon and glomalin accumulation, and their relationship with water stable aggregates. Results showed that mycorrhizic association is present all the year on studied plants, with values from 1.2 to 57% of mycorrhizal colonization, with variations depending on the season. The accumulation of carbon in the soil profile has significant differences between plants and ranged from 1.1 to 1.75% for <em>Larrea</em> and <em>Prosopis</em>, respectively. The water stable aggregates were significantly different between plants and ranged between 24% and 42%. Glomalin correlation with carbon content and water stable aggregates shows the role of mycorrhizal fungi on soil quality, highlighting influence on carbon content in rhizosphere.

Emissions of Methane and Nitrous Oxide from Rainfed Rice Field Treated with Different Rice Planting Systems and Nematicide Applications at Central Java, Indonesia

Rice field is issued as a source of greenhouses gases (GHGs) emissions especially methane (CH4) and nitrous oxide (N2O). Rice cultural approach could mitigate GHGs emissions i.e. through rice planting systems and nematicide application. The field experiment was conducted in rainfed rice field at Pati District, Central Java to determine effect of planting systems and nematicide application on emissions of methane and nitrous oxide from rainfed rice field. The six treatments were arranged in a randomized block design with three replicates, namely transplanted rice (TR) without applying nematicide, TR + neem cake, TR + carbofuran, direct seeded rice (DSR) without applying nematicide, DSR + neem cake, DSR + carbofuran. Parameters observed were methane flux, nitrous oxide flux, organic C content in rhizosphere, soil pH, soil redox potential surrounding rhizosphere of Ciherang variety. Methane emission under transplanted rice system was generally higher than direct seeded rice system. The treatment of DSR + neem cake resulted lowest methane emission (71 kg CH4 ha-1 season-1). The TR system emitted N2O lower significantly than the DSR system. Application of nematicide inhibitor materials decreased more effectively N2O emission. The DSR system increased significantly grain yield and N uptake, while application of nematicide materials didn’t increase grain yield but increased significantly N uptake. Normal 0 false false false IN X-NONE X-NONE [ How to Cite : Anicetus W and ES Harsanti. 2015. Emissions of Methane and Nitrous Oxide from Rainfed Rice Field Treated with Different Rice Planting Systems and Nematicide Applications at Central Java, Indonesia. J Trop Soils 20: 127-134. Doi: 10.5400/jts.2015.20.3.127 ]

Soil nitrogen content and enzyme activities in rhizosphere and non-rhizosphere of summer maize under different nitrogen application rates.

A field experiment was conducted on fluvo-aquic soil in the North China Plain to study the effects of nitrogen application rate on soil nitrogen contents and enzyme activities in rhizosphere and non-rhizosphere of summer maize. The results showed that the soil enzyme activities under different nitrogen application rates showed similar seasonal patterns. In comparison to no nitrogen ferti-lizer treatment, all nitrogen application treatments significantly increased NO3--N contents in rhizosphere and non-rhizosphere soils, NH4+-N content in rhizosphere soil and the activities of β-N-acetylglucosaminidase, β-glucosidase, β-xylosidase and Cellobiohyrolase. During the whole summer maize growing season, the NO3--N content in non-rhizosphere soil was significantly higher than that in rhizosphere soil. The NH4+-N content in non-rhizosphere soil was also significantly higher than that in rhizosphere soil at filling stage but significantly lower at seedling and maturity stages. Furthermore, soil enzyme activities in rhizosphere soil were significantly higher than those in non-rhizosphere soil. Effect of nitrogen application on soil organic carbon content was not significant. Soil total nitrogen content increased significantly when the nitrogen application rate was 0-180 kg·hm-2 but decreased significantly when the rate was higher than 180 kg·hm-2. Generally, a proper rate of nitrogen fertilizer application could significantly increase soil enzyme activities and total nitrogen content, and then improve soil biochemistry properties.

Effect of migration of amorphous iron oxide on phosphorous spatial distribution in constructed wetland with horizontal sub-surface flow

In a laboratory-scale constructed wetland (CW) with horizontal sub-surface flow, the migration of amorphous oxide iron (AOI) in medium and spatial distribution of phosphorus (P) were researched. Five months after treating wastewater, AOI concentration of medium changed in different area of the wetland medium bed. Compared with the medium before wastewater treatment, it rose in front rhizosphere and decreased in whole non-rhizosphere, remained almost the same in the back rhizosphere. In addition, iron plaque containing much AOI appeared on surface of all plant roots. The Fe level of root iron plaque reached about 25.88±9.92 (n=6) and 17.33±2.72 (n=6)g Fe/kg dried root in the front and the back area respectively. These should be resulted from the migration of the AOI from non-rhizosphere to rhizosphere in the CW. The P distribution was impacted by the migration. The medium had higher P content in rhizosphere than the one in non-rhizosphere because of its higher AOI concentration. Corresponding to the Fe level of iron plaque in different areas, P levels of plant biomass and root iron plaque in front area also were higher than the ones in back area.

Seasonal changes in microbial community structure and nutrients content in rhizospheric soil of Aegle marmelos tree

A preliminary investigation was carried out on dominance of different types of microbial communities at different monsoon seasons in rhizospheric soils of Aegle marmelos tree. Nutrients content of soil were also determined simultaneously to correlate with the microbial population. Results show that the rhizosphere of Aegle marmelos contains gram-negative bacteria, Rhizobium, Azotobacter, Actinomycetes and Yeast and major plant nutrients and their count as well as dominance changes with moisture content in rhizosphere. Except actinomycetes all the microorganisms were found highest during monsoon season whereas in post-monsoon season Actinomycetes were dominant. Amount of water in rhizosphere soil also affects soil chemical properties. Soil pH, organic carbon, C:N ratio, available nitrogen and available phosphorus were recorded maximum in monsoon whereas electrical conductivity and total nitrogen content were found maximum in post-monsoon.

Carbon Balance of a Winter Wheat-Root Microbiota System Under Elevated CO2

We examined the carbon budget of young winter wheat plants and their associated microorganisms as affected by a doubling of the atmospheric CO2 concentration (700 µmol mol-1). Plants were grown hydroponically in pre-sterilised sand at a controlled irradiance and temperature regime. Net photosynthesis (PN) and respiration (RD) rates of roots and shoots were measured continuously, plant growth and carbon distribution in the plant-root medium-associated microorganism system were determined destructively in interval-based analyses. PN in elevated CO2 grown plants (EC) was 123% of that in the control (AC) plants when averaged over the whole life span (39-d-old plants, 34 d in EC), but the percentage varied with the developmental stage being 115, 88, and 167% in the pretillering, tillering, and posttillering phase, respectively. There was a transient depression of PN, higher amplitude of day/night fluctuations of the chloroplast starch content, and depression of carbon content in rhizosphere of EC plants during the period of tillering. After 34 d in EC, carbon content in shoots, roots, and in rhizodepositions was enhanced by the factors 1.05, 1.28, and 1.96, respectively. Carbon partitioning between above and belowground biomass was not affected by EC, however, proportionally more C in the belowground partitioning was allocated into the root biomass. Carbon flow from roots to rhizodepositions and rhizosphere microflora was proportional to PN; its fraction in daily assimilated carbon decreased from young (17%) to order (3-4%) plants.

Effect of rice variety on zinc, cadmium, iron, and manganese content in rhizosphere and non‐rhizosphere soil fractions

In research on selecting rice (Oryza sativa L.) cultivars that are resistant to metal toxicity, an experiment was carried out with the objective of determining the effects of rice cultivars with differing oxidizing powers on the forms of metals in the rhizosphere soil. Four rice varieties were grown for 40 d in 3 soils which had differing amounts of iron (Fe) and manganese (Mn) oxides. The rhizosphere soil was kept separate from the non‐rhizosphere using nylon mesh “rhizobags”;. The soils were treated with either 5 mg/kg cadmium (Cd) or 20 mg/kg zinc (Zn). At the end of the experiment the soils were analyzed using a sequential fractionation scheme for five forms of Cd, Zn, Fe, and Mn. The rhizosphere soil was lower in pH (p=0.14) and P (p=0.05) than the non‐rhizosphere soil. Iron in the Mn oxide fraction was ten times higher in the rhizosphere as opposed to the non‐rhizosphere soil while the rhizosphere soil Mn was lower in this fraction. Cadmium in the rhizosphere soil was increased in both the exchangeable and organic matter fractions. Rice with higher oxidizing power decreased the Mn in the Mn oxide fraction, since the Mn reduced by submergence was oxidized by the oxygen supplied by the roots. Rhizosphere soil Zn increased in the Mn oxide fraction indicating that it may have been adsorbed or occluded by the oxides freshly precipitated by the roots. This increase coincided with a decrease of Zn in the exchangeable fraction. The increase in Zn in the Mn oxide fraction coupled with a decrease in more plant‐available fractions indicated that rice cultivars with high oxidizing power can alter the rhizosphere forms of metals so as to decrease their plant availability.

The Effect of Nitrogen Content in Rhizosphere on the Early Growth of Rice Plant

The Effect of Nitrogen Content in Rhizosphere on the Early Growth of Rice Plant