Soil Acid Phosphatase Activity Research Articles

Plant Performance and Soil Microbial Responses to Irrigation Management: A Novel Study in a Calafate Orchard

Calafate fruits have a high content of phenolic compounds and an antioxidant activity up to four times higher than that of blueberries. The establishment of a calafate orchard and irrigation responses on fruit and soil characteristics have been scarcely studied. Therefore, the objective of this study was to evaluate the effect of water replenishment rate: 0%, 50%, 100% and 150% of reference evapotranspiration (ET0), on soil microbiological activity, plant physiological response, fruit yield and chemical composition in a calafate orchard. The results showed that irrigation at 50% ET0 presented significant increases in soil urease, dehydrogenase and acid phosphatase activity. Likewise, irrigation at 50% ET0 significantly increased stomatal conductance and plant chlorophyll index, which led to a significant increase in fruit yield being 60% higher compared to the other treatments. Despite the higher fruit yield, 50% ET0 irrigation had a similar level of total anthocyanins and ORAC antioxidant capacity as the 100% ET0 treatment. In contrast, 0% and 150% ET0 treatments showed a higher degree of stress and got higher values for total anthocyanins and fruit antioxidant capacity. Irrigation rates 50% ET0 increases fruit yield while maintaining fruit quality and optimizing water resources in commercial orchards of calafate.

Effects of Applying Different Organic Materials on Grain Yield and Soil Fertility in a Double-Season Rice Cropping System

Double-cropping rice cultivation reduces soil fertility, and the extensive use of chemical fertilizers has harmful effects on both the environment and grain yield. The application of organic materials could be used as a practical strategy to maintain soil fertility and improve grain yield in a double-season rice cropping system. For this purpose, field experiments with six growing seasons over three years, from 2016 to 2018, were conducted to assess the effects of five organic materials (biochar, Chinese milk vetch, rice straw, rapeseed cake fertilizer, and manure) on the grain yield and soil fertility, aiming to save about 25% of the chemical nitrogen (N) fertilizer required for all rice growing stages. The result showed that, compared with CK (the most common dose of fertilizer in this study region; 100% chemical fertilizer without organic fertilizer), the grain yield and soil fertility of double-cropped rice were increased after applying organic fertilizers for three consecutive years. Specifically, the CRC treatment (Chinese milk vetch (10.77 t ha−1 in fresh)/rice straw (26.51 t ha−1 in fresh) + 75% chemical fertilizer) showed significantly higher rates of effective panicles (4.65–10.92%) and annual grain yield (8.00–8.82%). The total N, total phosphorus (P), total potassium (K), alkaline N, and available P content in the CRC soil were significantly increased by 11.85%, 12.22%, 15.08%, 23.32%, and 41.04%, respectively, relative to CK. The decomposition of the applied Chinese milk vetch and rice straw combined with 75% chemical fertilizer resulted in more soil humus (9.50 g kg−1), humic acid (3.19 g kg−1), fulvic acid (3.26 g kg−1), and active organic carbon (5.78 g kg−1) and a significantly higher carbon pool management index (13.5%), as well as significantly higher soil urease activity (18.10%) and acid phosphatase activity (17.64%). Therefore, in this study, Chinese milk vetch (10.77 t ha−1 in fresh) in the early rice season/rice straw (26.51 t ha−1 fresh) in the late rice season + 75% chemical fertilizer treatment was the optimal dose for the double-season rice cropping system. It resulted in higher rice yields and has the potential to be used for more sustainable soil fertility.

Spatial Heterogeneity of Soil Bacterial Community Structure and Enzyme Activity along an Altitude Gradient in the Fanjingshan Area, Northeastern Guizhou Province, China.

Changes in altitude can cause regional microclimate changes, leading to the spatial heterogeneity of environmental factors and soil bacteria. However, the internal driving process and mechanism remain unclear. Here, we selected Fanjingshan, a typical nature reserve in the subtropical region of south China with a clear altitudinal belt, to reveal the response mechanisms of microbial populations with altitude changes. We examined the physiochemical and biological properties (pH and soil enzyme activities) of 0~10 cm soil layers, soil bacterial diversity, and community structure across the 2.1 km belt (consisting of six altitude ranges). Our results showed that soil pH was highest at the altitude range below 900 m and decreased with altitude thereafter. Soil enzyme activities showed an overall decreasing trend with altitude rising. The soil sucrase and catalase activity was highest (48.35 mg.g-1.d-1 and 23.75 µmol.g-1, respectively) at altitudes below 900 m; the soil urease activity was highest (704.24 µg.g-1.d-1) at 900~1200 m; and the soil acid phosphatase activity was highest (57.18 µmol.g-1) at 1200~1500 m. In addition, the soil bacterial community diversity showed a linear increasing trend, with the maximum abundance at 1500~1800 m. Soil pH was correlated with enzyme activity and bacterial community composition and structure, and the correlation was the strongest between pH and the distribution of bacterial diversity at altitudes below 900 m. Overall, soil enzyme activities and soil bacterial diversity showed spatial heterogeneity along the altitude gradient, and their community structure and composition were affected by altitude as a result of changes in soil physicochemical factors. This study provides a better and deeper understanding of the spatial succession of soil in the Fanjingshan area and the distribution pattern of soil microorganisms in central subtropical mountain ecosystems.

Impact of In-situ Paddy Straw Burning on Soil Enzyme Activity, Soil Microbial Population and Green House Gas Emissions in Sandy Loam Soil

The rice - maize cropping system is one of the predominant cropping systems in Telangana state, which also produces large quantities of residues, whose disposal is a major problem. A large quantity of paddy straw is burnt on the farm to clear the field for succeeding crop. On the farm, a significant amount of paddy straw is burned to prepare the land for a subsequent crop. Burning crop residue damages the air and results in the loss of a significant amount of biomass plant nutrients and the entire amount of carbon. The purpose of the study was to investigate the impact of paddy straw burning on soil biological properties (enzyme activities, microbial population) and to know the amount of green house gas (GHG) emissions released due to burning of residue, under two tillage systems viz., no tillage and conventional tillage. Results indicated that there was a significant decrease in soil microbial population, dehydrogenase activity (41.52% in NT and 40.07% in CT), acid and alkaline phosphatase activity and urease activity in soil due to residue burning. It also indicated that there was a rise in CO2, CH4 and N2O emissions 48 hours after residue burning. It can be concluded that crop residue burning leads to decrease in the enzyme activities and soil microbial population. It also leads to rise in green house gas emissions. The impact of rice straw burning on different microbial genera has to be further studied by researchers.

Ecological Responses of Maize Rhizosphere to Antibiotics Entering the Agricultural System in an Area with High Arsenicals Geological Background.

Metal(loid)s can promote the spread and enrichment of antibiotic resistance in the environmental ecosystem through a co-selection effect. Little is known about the ecological effects of entering antibiotics into the environment with long-term metal(loid)s’ resistance profiles. Here, cow manure containing oxytetracycline (OTC) or sulfadiazine (SA) at four concentrations (0 (as control), 1, 10, and 100 mg/kg) was loaded to a maize cropping system in an area with high a arsenicals geological background. Results showed that exogenous antibiotics entering significantly changed the nutrient conditions, such as the concentration of nitrate nitrogen, ammonium nitrogen, and available phosphorus in the maize rhizosphere soil, while total arsenic and metals did not display any differences in antibiotic treatments compared with control. Antibiotics exposure significantly influenced nitrate and nitrite reductase activities to reflect the inhibition of denitrification rates but did not affect the soil urease and acid phosphatase activities. OTC treatment also did not change soil dehydrogenase activities, while SA treatment posed promotion effects, showing a tendency to increase with exposure concentration. Both the tested antibiotics (OTC and SA) decreased the concentration of arsenite and arsenate in rhizosphere soil, but the inhibition effects of the former were higher than that of the latter. Moreover, antibiotic treatment impacted arsenite and arsenate levels in maize root tissue, with positive effects on arsenite and negative effects on arsenate. As a result, both OTC and SA treatments significantly increased bioconcentration factors and showed a tendency to first increase and then decrease with increasing concentration. In addition, the treatments decreased translocation capacity of arsenic from roots to shoots and showed a tendency to increase translocation factors with increasing concentration. Microbial communities with arsenic-resistance profiles may also be resistant to antibiotics entering.

Effects of the Continuous Cropping of Amomum villosum on Rhizosphere Soil Physicochemical Properties, Enzyme Activities, and Microbial Communities

Amomum villosum, which is an important perennial medicinal plant, easily suffers from continuous cropping obstacles in the plantation. The aim of this study is to find an effective method to solve the problem of A. villosum continuous cropping. In this study, we analyzed four fields in which A. villosum was continuously cropped and a fallow field to reveal the effects of continuous cropping on the rhizosphere soil physicochemical properties, enzyme activities, and bacterial and fungal communities. Most of the soil nutrient contents gradually increased as the number of years of continuous cropping increased, whereas the soil pH decreased slightly. The soil urease and acid phosphatase activities tended to increase as the length of the continuous cropping period increased, which may have accelerated the conversion of soil substances. Furthermore, the alpha diversity of the bacterial and fungal communities decreased as the duration of the continuous cropping period increased. Additionally, the redundancy analysis revealed that bacterial and fungal community structures at the phylum level were the most correlated with pH value and catalase activity, respectively. This study may be useful for promoting the continuous cropping and sustainable development of A. villosum.

Responses of root and soil phosphatase activity to nutrient addition differ between primary and secondary tropical montane forests

Phosphatases play a vital role in phosphorus (P) acquisition for both plant roots and soil microbes. However, how this P-acquisition strategy responds to exogenous nitrogen (N) and P input in tropical forests of different successional stages remains unclear. Using the 7-yr N and P addition experiment in two tropical montane forests under different successional stages (primary and secondary), we investigated the responses of root and soil acid phosphatase (AcP) activity to nutrient addition. Results showed that in both the primary and secondary forest, there is a general pattern that root and soil AcP were both enhanced by N addition while suppressed by P addition and NP addition, but the effect varies between two sources and between two forest types. Specifically, P addition significantly reduced root AcP activity by 74.8% in the secondary forest, while reduced soil AcP activity by 42.8% in the primary forest; only root AcP activity in the primary forest was significantly enhanced with increasing N addition rates. Both root and soil AcP activities were negatively correlated with soil total P when data from two forest types were combined, whereas no significant relationship was detected between soil available P and root or soil AcP activity in the primary forest or in the secondary forest. Moreover, root AcP activity was significantly higher in the slow-growth primary forest (12.3 μmol g−1 h−1) compared to the fast-growth secondary forest (6.3 μmol g−1 h−1). Overall, we verified the widespread pattern that N addition increases while P addition suppresses soil AcP activity and found a similar pattern in root AcP activity in two tropical montane forests, indicating that plants and soil microbes have consistent responses to nutrient addition. We also emphasized the potential role of the successional stage of tropical forests in regulating root AcP activity.

Intercropping regulation of soil phosphorus composition and microbially-driven dynamics facilitates maize phosphorus uptake and productivity improvement

Intercropping is a powerful way that promote a more diversified plant community in croplandas. It is important to understand how this practice regulates phosphorus (P) footprint and trade-off in plant-soil system which influences crop productivity. Herein, a field-based experiment was conducted to investigate the effects of intercropping of maize with legumes (peanut and soybean) and non-legumes (gingelly and sweet potato) on maize productivity and P transformation and regulation. Compared with the monoculture, intercropping treatments increased maize yield, P use efficiency (PUE), P partial factor productivity (PFPP), and aboveground P uptake by 13.3–34.4%, 6.2–41.2%, 13.6–68.2%, and 10.3–20.1%, respectively. Intercropping treatments significantly reduced the cumulative losses of total P, dissolved P, and particulate P by 4.7–60.1%, 3.2–67.1%, and 2.7–64.7%, respectively. Maize/peanut and maize/soybean systems showed a better advantage in improving maize productivity and mitigating P runoff loss than the maize/gingelly and maize/sweet potato. Compared with the monoculture, intercropping increased the contents of soil labile-P, stable-P, solution-P, hydrolysable-P, and exchangeable-P by 3.1–7.8%, 18.7–63.2%, 8.4–35.5%, 0.2–28.3%, and 38.6–637.1%, respectively. The potential activities of soil alkaline and acid phosphatase in intercropping treatments increased respectively by 15.3–173.7% and 5.6–215.2% compared with the monoculture. Maize productivity components (crop yield, PFPP, and PUE, and plant P uptake) were positively correlated with soil P composition and bioavailability, microbial biomss P, and phosphatase activity, while negatively correlated with P runoff loss (P < 0.05). Those findings highlight the importance in understanding how soil P composition and microbially-driven P dynamics mediates plant P uptake to determine the consequences of intercropping for maize productivity. • Intercropping increased maize yield and PUE by 13–34% and 6–41%, respectively. • Intercropping decreased the runoff loss of TP, DP, and PP by 5–60%, 3–67%, and 3–65%. • Intercropping increased soil phosphatase activities by 6–215% with maize development. • Increased productivity was related to soil P composition, bioavailability, and dynamics. • Intercropping-driven plant-soil P trade-off contributed to maize productivity improvement.

Spatial Changes in Glomalin-Related Soil Protein and Their Correlation with Soil Properties in the Black Soil Region of Northeast China

Glomalin-related soil protein (GRSP), soil nutrients, and soil enzyme activities are closely related to soil fertility and land productivity, which play an important role in indicating soil quality. Little is known about the spatial variation in GRSP and its relationship with edaphic factors. Here, the spatial distribution of GRSP, soil chemical properties, and the soil enzyme activities of 0–20 cm depth farmland soil in the black soil region of northeast China were investigated, and the relationships among edaphic factors were analyzed collected from 41 sampling sites. The results indicate that GRSP, soil organic matter, total nitrogen, and acid phosphatase activities showed significant patterns of spatial variation, generally decreasing from north to south along a latitudinal gradient. Principal component analysis revealed that total GRSP (by 80.19%) and soil organic matter content (by 80.15%) were the greatest contributing factors accounting for the variations. Edaphic factors such as soil organic matter, total nitrogen, total phosphorus, and acid phosphatase were significantly positively correlated with GRSP, while urease was negatively correlated with GRSP. Mantel tests also showed that soil organic matter, total nitrogen, urease, and acid phosphatase were positively correlated with GRSP. The results reflect the soil fertility characteristics of the black soil region of northeast China and reveal the relationship among edaphic factors. These findings could be used to inform agricultural production and provide new insight into the role of GRSP in soil quality.

Arbuscular mycorrhizal fungi and phosphorus supply accelerate main medicinal component production of Polygonum cuspidatum.

The medicinal plant Polygonum cuspidatum Sieb. Et Zucc is rich in stilbenes (e.g., polygonin and resveratrol) and anthraquinones (e.g., emodin) for the therapy of human diseases, while how to increase the growth and medicinal composition concentrations of P. cuspidatum has become an urgent issue. The aim of the present study was to evaluate the effects of inoculation with an arbuscular mycorrhizal (AM) fungus, Funneliformis mosseae, on plant growth, phosphorus (P) acquisition, medicinal component concentrations, and expressions of resveratrol synthesis-associated enzyme genes of P. cuspidatum at two P levels (0 M and 0.2 M). P supply (0.2 M) stimulated root AM fungal colonization rate. F. mosseae inoculation significantly improved growth performance (height, diameter, and biomass) and root morphology (diameter, length, and projected area), irrespectively of substrate P levels. P supply and F. mosseae distinctly increased soil acid and neutral phosphatase activities, as well as root P concentrations. P supply increased root physcion and resveratrol concentrations in inoculated and uninoculated plants, along with up-regulated expressions of PcCHS1, PcCRS1, PcRS11, and PcSTS. AM plants represented significantly higher root aloe-emodin, chrysophanol, emodin, physcion, polydatin, and resveratrol concentrations than non-AM plants irrespective of P levels, coupled with up-regulated expressions of PcCHS1, PcCHS2, PcRS11, PcRS, and PcSTS. It is concluded that 0.2 M P supply and F. mosseae inoculation promoted chrysophanol, physcion, polydatin, and resveratrol concentrations of P. cuspidatum, with the increase in resveratrol associated with up-regulated expressions of related genes.

Halotolerant rhizobacterial consortium confers salt tolerance to maize under naturally salt‐affected soil

AbstractHalotolerant rhizobacteria, which are able to withstand higher concentrations of salts, are useful for conferring salinity tolerance to agricultural crops and improving soil fertility through their different activities. Among their various mechanisms, the improvement in soil enzyme activities they bring about through production of extracellular enzymes is crucial. Soil enzymes are responsible for supplying nutrients to plants under stressed conditions. In the current study, halotolerant plant growth‐promoting rhizobacteria (Bacillus and Acinetobacter) species were examined individually and in combination to compare the efficiency with which they improve soil enzyme activities under naturally salt‐affected soil conditions. The microbial consortium caused a significant increase in the soil urease (1.15‐fold), dehydrogenase (14%), acid phosphatase (78%), and alkaline phosphatase (52%) activities, which led to a significant increase in shoot N (42%), grain N (98%), straw P (40%), and grain P (44%) in comparison with the uninoculated control. In addition, application of the microbial consortium to maize (Zea mays L.) seeds led to considerable improvements in plant height (70%), cob length (67%), grain yield (69%), stomatal conductance (17%), water‐use efficiency (96%), photosynthetic rate (22%), cob weight (1.63‐fold), and transpiration rate (1.2‐fold). Moreover, consortium inoculation resulted in a significant reduction in leaf Na+ (38%) content, as evidenced by reduced antioxidant activities (i.e., catalase [59%], superoxide dismutase [37%], glutathione reductase [45%], ascorbate peroxidase [19%], and malondialdehyde [53%]) after consortium application. In conclusion, the rhizobacterial consortium alleviated the negative impacts of salinity on maize growth by improving the soil enzyme activities and nutrient acquisition under salinity stress.

Characteristics of Microbial Community Structure in the Surrounding Farmlands of a Mercury Mining Area and Its Environmental Driving Factors

In order to investigate the characteristics of soil microbial community structure and their relationships with environmental factors in the surrounding farmlands of a mercury mining region, we analyzed soil physical and chemical properties, Hg pollution, enzyme activity, and microbial community structure characteristics in the surrounding farmlands of a mercury mining region in Tong Ren (Bahuang Town, Bijiang District; Huaqiao Town, Shiqian County; Kaide Town, Jiangkou County; and Chuantong town, Bijiang District; referred to as BJ, SQ, JK, and TR, respectively). The relationships between the characteristics of soil microbial community structure and environmental factors were determined using redundancy analysis (RDA) and correlation network analysis. The results showed that the degree of soil Hg contamination varied depending on the sampling locations in the study region. The soils in JK and TR were categorized as having light-level Hg contamination, whereas those in SQ and BJ were at moderate-level Hg contamination. The potential ecological risk indicated that the soil suffered different degrees of Hg contamination (TR was at a medium level, BJ and JK were at a serious level, and SQ was at a high severe level of pollution). The dominant bacteria flora were Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi, whereas the dominant flora of fungi included Ascomycota, Basidiomycota, and Mortierellomycota. RDA analysis showed that pH, sucrase (SC), and catalase (CAT) activities were the key environmental factors of soil bacterial community structure. Soil pH, available nitrogen (AN), available potassium (AK), HCl-Hg, acid phosphatase (ACP), and urease (URE) activities were the key environmental factors that affected soil fungal community structure. Correlation network analysis indicated that pH, available phosphorus (AP), HCl-Hg, SC, ACP, and CAT were the key environmental factors affecting soil bacterial community structure, including Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Firmicutes, Rokubacteria, and Planctomycetes. AK, pH, total nitrogen (TN), AP, AN, ACP, URE, and SC activities were the key environmental factors affecting soil fungal community structure, such as Ascomycota, Basidiomycota, Mortierellomycota, Glomeromycota, Chytridiomycota, Rozellomycota, Kickxellomycota, and Mucoromycota.

Relationships among phosphatase activities, functional genes and soil properties following amendment with the bacterium Burkholderia sp. ZP‐4

AbstractPhosphorus (P) limitation is common in subtropical and tropical regions. Although phosphate‐solubilizing bacteria (PSB) can transform soil P fractions and enhance soil P availability, the mechanism regarding the linkage between PSB abundance and soil P fractions transformation were still unknown. In this study, Burkholderia sp. ZP‐4, a PSB strain, was inoculated into subtropical bamboo forest soil at the inoculation rates of 0% (bacterial suspension: soil weight = v: w, the control), 2% (2%IR), 6% (6%IR) and 10% (10%IR). The changes in soil P fractions, bacterial community, phosphatase activities, P transforming functional genes and soil properties were also determined after the PSB inoculation. Compared with the control, soil inorganic P extracted by deionized water (H2O‐Pi) and extracted by sodium bicarbonate (NaHCO3‐Pi) in the 6%IR treatments were increased 45.35% and 16.05%, respectively. The lowest content of residual P (residual‐P) was in the 6%IR treatment among the four treatments. The 6%IR treatment contributed to stimulating and inducing soil acid phosphatase activity and P cycling genes (phoD and phoC) abundances, relative to the control. The PSB inoculation significantly decreased soil pH but increased soil available nitrogen P supplies among all treatments. Simultaneously, the PSB inoculation also significantly changed soil bacterial community. The transformation of P fractions in the 6%IR was more efficient than the other treatments, implying that 6% is the proper inoculation rate of functional Burkholderia for accelerating P cycling at subtropical bamboo forest soil. Our findings will provide a scientific guidance for the application of biofertilizer.

Partial substitution of chemical fertilizers with maize straw: Seeking long‐term improvement of rice yield by raising quality indicators of a red paddy soil

AbstractStraw application increases crop yield, but the underlying mechanisms of straw‐substitution for chemical fertilizer on yield is not completely understood. We hypothesized that straw application improves crop yield by improving soil quality. In order to clarify how partial substitution of chemical fertilizers with maize straw affects soil properties and the specific contribution of soil properties to double‐cropping rice yield, we selected a long‐term positioning test station operated since 1982 and designed three fertilization treatments: (1) single chemical fertilizers (CF); (2) medium replacement by maize straw under which 1/3 of nitrogen (N) fertilizer was replaced (MS); and (3) high replacement by maize straw under which 2/3 of N fertilizer was replaced (HS). The yield under HS of late and early rice increased by 42.66% and 25.04% in 2019 and 2020, respectively. Long‐term straw application significantly decreased soil bulk density, increased total porosity, and improved the stable aggregates content (&gt;0.25 mm). Straw application increased soil urease, protease, alkaline phosphatase (ALP), acid phosphatase (ACP) and catalase activities, microbial biomass carbon (C), microbial biomass N, and nutrients compared with CF. The structural equation model indicated that the tested soil properties explained 77% of the variations in observed rice yield. The rice yield was mainly indirectly affected by soil organic matter (SOM), microbial biomass, and enzyme activities. The results showed that straw substituted for chemical fertilizers increased rice yield. The key factors affecting yield under long‐term fertilization were SOM, microbial biomass, and enzyme activity, rather than soil N, phosphorus (P) nutrient contents, and bulk density.

Effect of cogenerated bagasse ash on microbial population and enzyme activities in sugarcane grown soil

A field experiment was conducted during 2016-18 on an Inceptisol of Rahuri, Maharashtra to study the effect of cogenerated bagasse ash on microbial population and enzyme activities in preseasonal sugarcane (Sachharum officinarum) var. CoM 0265. The results indicated that the treatments which received 150 % RDK through cogenerated bagasse ash recorded the higher total bacteria (44.11, 45.89 and 32.78 cfu x 106 g-1 soil), fungi (17.78, 18.89 and 15.89 cfu x 105 g-1 soil) and actinomycetes (18.33, 19.22 and 15.78 cfu x 105 g-1 soil) count at earthing up, grand growth and harvest stage of preseasonal sugarcane, respectively. On the other hand, the highest dehydrogenase (13.38, 14.03 and 7.92 µg TPFg-1 soil h-1), urease (49.35, 51.68 and 38.15 µg NH4-N g-1 soil h-1), acid phosphatase (17.92, 18.85 and 13.23 µg PNP g-1 soil h-1) and alkaline phosphatase (64.81, 65.94 and 39.07 µg PNP g-1 soil h-1) enzyme activity in soil were also recorded in T9 (150 % RDK through cogenerated bagasse ash) at earthing up, grand growth and harvest stage of preseasonal sugarcane, respectively. The results of the present study revealed that the microbial population and enzymatic activities of the soil were increased at initial stages and thereafter, progressively decreased with crop growth stages by the application of cogenerated bagasse ash. Application of 150 % RDK through CBA (6.62 t ha-1) along with recommended dose of nitrogen and phosphorous (340 and 170 kg ha-1) through inorganic fertilizers and 20 t ha-1 FYM has improved the microbial population as well as enzymatic activities in sugarcane grown soil.

Symbiotic Fungi Alter the Acquisition of Phosphorus in Camellia oleifera through Regulating Root Architecture, Plant Phosphate Transporter Gene Expressions and Soil Phosphatase Activities.

Plant roots can be colonized by many symbiotic fungi, whereas it is unclear whether and how symbiotic fungi including arbuscular mycorrhizal fungi and endophytic fungi promote phosphorus (P) uptake in Camellia oleifera plants. The objective of the present study was to analyze the effect of inoculation with a culturable endophytic fungus (Piriformospora indica), three arbuscular mycorrhizal fungi (Funneliformis mosseae, Diversispora versiformis, and Rhizophagus intraradices), and mixture of F. mosseae, D. versiformis and R. intraradices on plant growth, root architecture, soil Olsen-P, soil phosphatase activities, leaf and root P concentrations, and phosphate transporter gene expressions, in order to explore the potential and mechanism of these symbiotic fungi on P acquisition. All the symbiotic fungi colonized roots of C. oleifera after 16 weeks, with P. indica showing the best effect on fungal colonization. All the symbiotic fungi significantly increased acid, neutral, and total phosphatase activities in the soil, accompanied with an elevation of soil Olsen-P, of which P. indica presented the best effect. All symbiotic fungal treatments, except D. versiformis, significantly promoted plant growth, coupled with an increase in root total length, area, and volume. Symbiotic fungi almost up-regulated root CoPHO1-3 expressions as well as leaf CoPHO1-1, CoPHO1-3, and CoPHT1;4 expressions. Correlation analysis showed that P concentrations in leaves and roots were significantly positively correlated with root morphological variables (length, volume, and surface area) and soil acid, neutral and total phosphatase activities. It is concluded that symbiotic fungi, especially P. indica, played an important role in P uptake of C. oleifera plants through regulating root architecture, part plant phosphate transporter gene expressions and soil phosphatase activities.

Changes in litter input exert divergent effects on the soil microbial community and function in stands of different densities

Soil microbial communities influence soil biogeochemical cycling by affecting the production of extracellular enzymes and the release of carbon dioxide. Changes in litter input or stand density due to thinning can affect soil microbial communities and their function by altering soil biochemical properties. However, it is unclear how or to what extent different amounts of litter input affect soil microbial communities and their function in forest stands with different densities. Therefore, we simulated litter removal, 50 % litter reduction, normal litter input, and double litter increase under field conditions by applying different amounts of litter to soils with different stand densities in the laboratory. We then measured soil biochemical properties, microbial communities, enzyme activity, and respiration rate.Our results revealed that the responses of soil dissolved organic carbon and total nitrogen to litter input were more pronounced in the high-density forest stand with poor soil than in the low-density forest stand with nutrient-rich soil, which was mainly reflected in that the addition of litter significantly decreased the concentration of dissolved organic carbon while increasing the content of total nitrogen in the soil of the high-density forest stand. In comparison to the soil carbon component, the nitrogen component of the soil was more affected by stand density. The responses of soil fungal and bacterial communities to leaf litter treatment varied with stand density, as reflected primarily in changes in the relative abundances of Ascomycota, unclassified_K_fungi, and Proteobacteria, and changes in the relative abundances of their functional groups (ectomycorrhizal fungi, saprophytic fungi, pathogens, parasites, and bacteria involved in the nitrogen cycle). Soil fungal community responses to changes in litter input are more sensitive in the high-density forest with nutrient-poor soil than in the low-density forest stand. Furthermore, litter input inhibited the activities of soil β-glucuronidase, N-acetyl-β-d-glucosaminidase, and acid phosphatase more strongly in the low-density forest stand. Litter manipulation primarily affected enzymatic activity in the high-density forest stand by changing the diversity and composition of the soil fungal community. However, in the low-density forest stand, litter treatment affected soil enzyme activity, primarily through changes in soil bacterial and fungal community composition, as well as soil respiration through changes in bacterial richness (Chao 1) and community composition.We conclude that how the change in litter input impacts the soil microbial community and its function, or the magnitude of the effects, is largely dependent on soil quality. Relationships among soil variables, microbial communities, and function differ between stand densities. Our study contributes to an enhanced understanding of the impact of changes in litter input due to climate change or anthropogenic activities on soil biogeochemical cycles and can also guide rationally formulating forest management approaches to improve microbial function under climate change.

Root diameter decreases and rhizosheath carboxylates and acid phosphatases increase in chickpea during plant development

Background and aimsThis study investigated whether root traits at the seedling stage are maintained at the flowering stage in two chickpea (Cicer arietinum) genotypes with contrasting root morphology and physiology; and whether the genotype with greater rhizosheath carboxylates mobilises more poorly-available phosphorus (P) pools to increase shoot P at flowering/podding and seed yield at maturity.MethodsTwo chickpea genotypes were grown in a low P soil with or without P addition (0 and 40 µg P g−1 soil as KH2PO4) under controlled glasshouse conditions and harvested at seedling, flowering/podding, physiological maturity.ResultsAt the seedling and flowering/podding stages, ICC2884 had thinner roots and greater root mass ratio, specific root length and rhizosheath carboxylates per root dry weight (DW) than ICC456. Both genotypes had smaller root diameter, higher carboxylates and acid phosphatase activity in rhizosheath soil at flowering/podding than at seedling. In the rhizosheath soil of both genotypes, NaHCO3-Pi concentration was depleted under P0 only; under both P0 and P40, NaHCO3-Po concentration increased while NaOH-Pi and NaOH-Po concentrations decreased at the seedling stage but accumulated at the flowering/podding stage, relative to the bulk soil. ICC2884 did not mobilise more poorly available soil P or acquire more P at the seedling or flowering/podding stages, or produce higher seed yields than ICC456.ConclusionICC2884 and ICC456 maintained the difference in root morphological and physiological characteristics from the seedling stage to the flowering/podding stage. The genotype with greater rhizosheath carboxylates (root DW basis) did not produce higher yield than genotype with less rhizosheath carboxylates.

Changes in soil microecology of gangue reclamation areas after 10 years of in situ restoration with herbaceous plants (Artemisia sacrorum and Imperata cylindrica) and trees (Populus spp.)

Changes in the soil ecological microenvironment of coal gangue contaminated areas were evaluated after 10 years of in situ restoration with Artemisia sacrorum, Imperata cylindrica, and Populus spp. The changes in soil enzyme activity, ion spectrum, bacterial community structure and function, and metabolic spectrum were analyzed in an unrestored coal gangue pollution area (Control), an Artemisia sacrorum + Imperata cylindrica remediation area (T1), and a Populus remediation area (T2). Phytoremediation significantly increased the soil acid phosphatase activity by 4.62–7.36 times, and decreased the electrical conductivity by 6.2–85.5%. The overall reduction trend for heavy metals in the soil was shallow layer > middle layer > deep layer, with significant reductions seen for Cs, As, Co, Pb, Ni, U, and Cr. The number and diversity of shallow soil microbial communities increased significantly, with Actinobacteria, which participate in the carbon and nitrogen cycles, and Proteobacteria, which can tolerate/metabolize multiple heavy metals, becoming the dominant species in the restoration area. Microbial genes for glycosyltransferase, transcriptional regulators, and toluene degradation changed significantly. Phytoremediation by both remediation strategies significantly changed the metabolic level of lipids and lipid-like molecules in the soil, while significantly enriching the pathways of ABC transporters and galactose metabolism, which are essential for soil detoxification, ion transport, and carbon cycling. Bacteria such as Thiobacillus and Pseudarthrobacter were important drivers of soil metabolism. In general, the in situ phytoremediation of soil contaminated by coal gangue improved the overall soil ecological microenvironment.

Polyphosphate application influences morpho-physiological root traits involved in P acquisition and durum wheat growth performance

BackgroundAmong phosphate (P) fertilizers, polyphosphates (PolyPs) have shown promising results in terms of crop yield and plant P nutrition. However, compared to conventional P inputs, very little is known on the impact of PolyPs fertilizers on below- and above-ground plant functional traits involved in P acquisition. This study aims to evaluate agro-physiological responses of durum wheat variety ´Karim´ under different PolyPs applications. Three PolyPs fertilizers (PolyA, PolyB, and PolyC) versus one orthophosphate (OrthoP) were applied at three doses; 30 (D30), 60 (D60), and 90 (D90) kg P/ha under controlled conditions.The PolyPs (especially PolyB and PolyC) application at D60 significantly increased morphophysiological root traits (e.g., RL: 42 and 130%; RSA:40 and 60%), shoot inorganic P (Pi) content (159 and 88%), and root P acquisition efficiency (471 and 296%) under PolyB and PolyC, respectively compared to unfertilized plants. Above-ground physiological parameters, mainly nutrient acquisition, chlorophyll content and chlorophyll fluorescence parameters were also improved under PolyB and PolyA application at D60. A significant and positive correlation between shoot Pi content and rhizosphere soil acid phosphatase activity was observed, which reveal the key role of these enzymes in PolyPs (A and B) use efficiency. Furthermore, increased P uptake/RL ratio along with shoot Pi indicates more efficient P allocation to shoots with less investment in root biomass production under PolyPs (especially A and B).ConclusionsUnder our experimental conditions, these findings report positive impacts of PolyPs on wheat growth performance, particularly on photosynthesis and nutrient acquisition at D60, along with modulation of root morpho-physiological traits likely responsible of P acquisition efficiency.