Content Of Available Phosphorus Research Articles

An experiment was conducted to evaluate the soil fertility status of teaching and research farm of Federal Polytechnic Monguno (12°40'N, 13°36'E, 354m above sea level), for Pearl Millet (Pennisetum glaucum (L.) R. Br,) Production. A systematic grid sampling approach was used to collect composite soil samples from the study site during the 2025 dry season. Samples were analyzed at the Soil Chemistry Laboratory of the Department of Soil Sciences, University of Maiduguri for physico-chemical properties using standard laboratory procedures. Data collected were subjected to descriptive statistics using STATISTIX 10.0 analytical software. Relationships between soil properties were determined using Pearson correlation analysis. Fertility parameters were interpreted according to critical levels for millet production in semi-arid tropical regions. Results shows that the soil was sandy loam, with neutral pH (6.67) and non-saline (EC = 0.22). Low concentration of available phosphorus (6.398) and total nitrogen (1.102 g/kg) were observed. Organic carbon (3.56 g/kg) likewise the organic matter (6.236 g/kg) were extremely low. The C:N ratio (3.244) and sodium ion concentration (0.094 cmol(+)/kg Soil) were low, while calcium was moderate. Potassium was low (0.234 cmol(+)/kg Soil) while magnesium was very high. The soil had a moderate CEC and a very high PBS. Strong correlations exist between some essential nutrients and pH, EC, Na, Base saturation and percentage clay fractions. Nitrogen in the study area was observed to be inversely related with silt (r = -0.915). Phosphorus availability was largely determined by clay (r = 0.995), pH (r = 0.896), and EC (r = 0.999). A very strong negative correlation (r = -0.964) was observed between sand fraction and available P. The coefficient of variation (CV) values indicated moderate variability for most parameters. In conclusion, that the soil has the potential to support millet production, though, the evaluation showed that most of the essential nutrients needed for adequate millet production are low in concentration. It is therefore, recommended that, successful millet production at the study location will require integrated soil fertility management strategies that addresses multiple deficiencies while considering the soil's moderate nutrient retention capacity.

The objective of the study is to identify varieties of winter soft wheat adapted for cultivation in the conditions of the Udmurt Republic. Competitive variety testing was carried out in the experimental crop rotation of the Udmurt Research Institute of Agriculture, a structural subdivision of the Udmurt RC of the Ural Branch of the RAS, in 2021–2024. The object of research was nine varieties of soft winter wheat bred by the Udmurt RC of the Ural Branch of the RAS and the Volzhskaya K (standard) and Moskovskaya 39 varieties. Field experiments were carried out on sod-podzolic medium loamy soil with a pH ranging from slightly acidic to neutral, with a low humus content, a very high content of available phosphorus, and a medium and very high content of exchangeable potassium. In the studied years, meteorological conditions varied in terms of autumn and spring-summer vegetation conditions and wintering conditions. In the competitive variety testing of 2022–2024, high average yield (6.48 t/ha) was noted for the 23.12/23 (Udmurt Dunne) variety, the increase to the Volzhskaya K standard was 1.36 t/ha. The Udmurt Dunne variety also showed high general adaptive capacity (OACi = 1.26 t/ha), significantly exceeding this indicator of the Volzhskaya K standard. The varieties A-332/2, Volzhskaya K, Udmurt Dunne, 26.12/6, Cheberina, Moskovskaya 39, Lyubava were responsive to favorable environmental conditions. The varieties Italmas, 2.05/3 and K-65040 can be classified as extensive. The variety k-65040 (47.9), as well as the varieties 2.05/3, Cheberina, Italmas, Udmurt Dunne (28.7–35.9) had increased selection value (OAS taking into account stability). Limiting factors for the 2022 conditions were resistance to lodging and the spread of sclerotinia. A significant strong positive relationship between yield and the elements of ear productivity, resistance to powdery mildew, the date of the onset of the heading and wax ripeness phases was revealed under the drought conditions of 2023. In 2024, the development of snow mold had a strong negative impact on yield.

To face the current crisis in global fertilizer prices, especially in developing countries where their food security has been greatly affected, alternative sources must be found for phosphate fertilizers, whose main source is phosphate rock, which is non-renewable and subject to depletion. Therefore, this study aims to evaluate the effect of the incubation period on the availability and fractionation of phosphorus in saline sandy soil under bone char addition. About 100 g of soil was placed in an airtight plastic jar and mixed thoroughly by adding 0.4 g of bone char. This experiment was incubated for 7, 16, 35, 65, and 84 days. The results obtained from this study revealed a significant increase (p ≤ 0.01) in available phosphorus with applying bone char in saline soil after 7, 16, and 35 days of incubation compared to the initial soil (before the incubation and unamended). Relative to the initial soil, the concentration of available phosphorus increased by 33.7%, 19.5%, and 12.3% after 7, 16, and 35 days, respectively. The results showed that increasing the incubation time significantly decreased phosphorus availability in saline soil after bone char application. The NaHCO3-Pi, HCl-Pi, and Res-Pi fractions increased significantly with the addition of bone char to the soil under study at all incubation periods compared to the initial soil. Inorganic phosphorus fractions after bone char application to saline sandy soil followed the order of HCl-Pi > Res-P > NaHCO3-Pi > NaOH-Pi > NH4Cl-Pi. In this context, these findings concluded that bone char amendment could be a potential P-source for agriculture in saline sandy soils to confront the high prices of phosphate fertilizers.

Red soil regions commonly experience land degradation and low nutrient availability. Excessive fertilizer use in recent years has intensified these challenges, necessitating scientifically informed fertilization strategies to ensure agricultural sustainability. To identify optimal fertilization strategies for maize cultivation in Yunnan’s red soil regions, this study conducted field experiments involving partial substitution of nitrogen fertilizer with organic manure to determine whether this approach improves soil health and boosts maize yield. Four treatments were compared in a randomized complete block design over one growing season: no fertilization (NF), soil testing and formula fertilization (STF), 15% organic fertilizer (swine manure) replacing nitrogen fertilizer (OF15), and 30% organic fertilizer replacing nitrogen fertilizer (OF30). The results indicated that substituting organic fertilizer for nitrogen fertilizer reduced soil acidification while increasing total phosphorus (TP) and available phosphorus (AP), thereby enhancing soil physicochemical properties. Maize grown under OF30 exhibited improved agronomic traits including plant height, stem diameter, ear height, and ear length. Additionally, the partial replacement of synthetic fertilizer with organic fertilizer notably increased maize yield and the weight of 100 grains, but there was no significant difference (p < 0.05) between OF15 and OF30. Moreover, the OF30 treatment generated the highest economic return of 25,981.73 CNY·ha−1. Correlation and principal component analyses revealed that substituting organic fertilizer for nitrogen fertilizer notably influenced total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), and yield, with maize yield positively correlated with TP and AP content. This study presents evidence that replacing 30% of nitrogen fertilizer with organic fertilizer is a viable strategy to enhance soil health, maize productivity, and profitability in Yunnan’s red soil regions, providing a crucial scientific foundation to support sustainable agricultural development in the region.

Exploring the differential responses of rhizosphere soil phosphorus contents associated with nitrogen-fixing and non-nitrogen-fixing plants to different soil nitrogen levels in subtropical karst forests can provide valuable insights into the effects of nitrogen-fixing plants on soil nutrient cycling. Such knowledge will serve as a scientific reference for the extensive planting of nitrogen-fixing plants in vegetation restoration efforts in karst regions. Taking karst forests with varying soil nitrogen levels in Jianshui County, Yunnan Province as test objects, we collected soil samples from the rhizosphere of three types of dominant nitrogen-fixing and non-nitrogen-fixing plants with the same age and analyzed the total phosphorus (TP), organic phosphorus (OP), inorganic phosphorus (IP), available phosphorus (AP), and other soil physicochemical properties. Soil microbial biomass and enzyme activities were measured to assess the influence of nitrogen-fixing plants on rhizosphere soil phosphorus contents under different soil nitrogen levels, as well as the main driving factors. Results showed that the contents of TP, OP and AP in the rhizosphere soil of nitrogen-fixing plants significantly increased by 16.0%, 66.5% and 139.5% under a low soil nitrogen level with the available nitrogen of 15.62 mg·kg-1, and significantly increased by 13.5%, 25.7% and 15.7% under higher soil nitrogen level with the available nitrogen of 37.15 mg·kg-1, respectively. There was no significant difference in IP content between nitrogen-fixing and non-nitrogen-fixing plants under the two soil nitrogen levels. Compared with low soil nitrogen level, the contents of TP and IP in the rhizosphere soil of nitrogen-fixing plants under high soil nitrogen level significantly decreased by 21.3% and 31.7%, and those of non-nitrogen-fixing plants significantly decreased by 19.6% and 39.1%. The AP content in the rhizosphere soil of nitrogen-fixing and non-nitrogen-fixing plants significantly increased by 32.8% and 174.8%, respectively, with no notable change in OP content. Under low nitrogen conditions, nitrogen-fixing plants significantly increased microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP), and alkaline phosphatase (ALP) activity in the rhizosphere soil. Under high nitrogen condition, nitrogen-fixing plants significantly increased MBP and ALP activity, but had no significant effect on MBC and MBN. As soil nitrogen level increased, soil MBC, MBN, MBP, and nitrogen cycle-related enzyme activities in the rhizosphere soil of nitrogen-fixing plants decreased significantly, while ALP activity increased. In contrast, in the rhizosphere soil of non-nitrogen-fixing plants, MBN and ALP activity significantly increased, while nitrogen cycle-related enzyme activities significantly decreased. Mantel analysis indicated that under low nitrogen level, rhizosphere soil phosphorus contents were primarily regulated by a combination of soil physicochemical properties, microbial biomass, and enzyme activity, while they were mainly regulated by soil physicochemical properties under high nitrogen level. In conclusion, compared to non-nitrogen-fixing plants, nitrogen-fixing plants in subtropical karst forests can significantly increased soil TP, OP, and AP contents and this effect is largely regulated by soil nitrogen level. Therefore, introducing nitrogen-fixing plants into low-nitrogen subtropical karst areas at the beginning of vegetation restoration may alleviate phosphorus limitation, improve soil nutrient status, and facilitate vegetation restoration in these regions.

Phosphate-solubilizing bacteria facilitate rhizospheric processes of Bidens pilosa L. in the phytoremediation of cadmium-contaminated soil: Link between phosphorus availability and cadmium accumulation.

Abstract Straw and coal gangue, primary wastes from agriculture and industry, respectively, have the potential to improve soil nutrients. The impact of plant species and microbial nutrient activation on this improvement warrants further investigation. A greenhouse experiment was conducted to examine how phosphorus-solubilizing bacteria (PSB) and mulch made from coal gangue and straw affect soil available phosphorus (AP), available silicon (ASi), and plant growth. These species include two economic crops, Gossypium hirsutum and Glycine max, and two plants used for mining remediation, Solanum nigrum and Medicago sativa. We found that the effects of mulching with coal gangue and straw on soil AP, ASi, and plant growth were influenced by plant species. The soil AP and ASi contents were significantly positively correlated in G. max and S. nigrum, and the mixed mulch significantly increased the soil AP and ASi contents for G. max and S. nigrum. The mixed mulch significantly increased the total biomass of G. max, with no significant effect on the biomass of other plants. These findings suggest that planting G. max could be an optimal strategy for improving soil with straw and coal gangue. The enhancement effects of the mixed mulch on soil AP and ASi of S. nigrum and the total biomass of G. max were negated by PSB, while PSB increased the soil AP and ASi contents of M. sativa with the mixed mulch. We demonstrated the necessity of planting suitable species and judiciously using microbial inoculants during the use of waste.

Nitrogen (N) addition is a critical driver of soil organic carbon (SOC) sequestration and nutrient cycling in croplands. However, its spatial variability and long-term effects under diverse environmental conditions remain poorly understood. We synthesised data from 479 cropland sites across China and apply machine learning models to evaluate the impacts of N addition on SOC and key soil nutrient indicators, including total nitrogen (TN), nitrate (NO₃⁻-N), ammonium (NH₄⁺-N), the carbon-to-nitrogen ratio (C/N), and available phosphorus (AP). We further evaluated the moderating roles of climate zones, fertiliser types, and fertilisation duration. Our findings demonstrate that N addition significantly increased SOC, TN, NO₃⁻-N, NH₄⁺-N, and AP contents, whereas the C/N ratio remains unaffected. SOC sequestration was greater in arid regions, whereas nutrient accumulation was more pronounced in humid zones. Organic and integrated (organic-inorganic) fertilisers outperformed chemical ones in enhancing SOC and nutrient cycling. Long-term N input (> 10 years) markedly intensified SOC storage and nutrient accumulation. We further developed the high-resolution (5 km) national-scale dataset that predicts the spatial responses of SOC and nutrient dynamics to nitrogen addition across China. This AI-derived dataset enables automated mapping of soil carbon and nutrient functions, capturing substantial spatial heterogeneity under varying environmental conditions. These results provide critical insights for optimising nitrogen management strategies, enhancing soil carbon sink functions, and informing precision agriculture policies in China.

Application of phosphorus (P) fertilizer is commonly based on soil testing for which a variety of soil P extraction methods are in use. The aim of this study was to compare three methods of P extraction from soils that had been derived from three parent materials in terms of their extraction yield and relation to soil properties. To achieve this, soils derived from Coastal plain sand (CPS) from Obio Akpa in Oruk Anam LGA, Beach ridge sand (BRS) from Ikot Akpaden in Mkpat Enin LGA and Sandstone (SS) from Ikot Obio Ise in Ini LGA were sampled at two depths (0-15 and 15-30 cm). The soil samples were processed in the laboratory and used to conduct routine analyses. For P determination, three extractants, i.e., H2O, CaCl2 and Bray-2 were used. The extracted P varied in concentration and increased in the order H2O <CaCl2 < Bray-2 being more efficient in the extraction of P in BRS, SS and CPS. Indications from this study is that Bray-2 is a suitable extractant that could be used for P extraction in the studied soils.

Growing cover crop mixtures is a sustainable agriculture tool that helps to reduce fertilizer use and, at the same time, ensures lower environmental pollution. The aim of this research is to assess the biomass of the aboveground part of cover crop mixtures and the nutrients accumulated in it and to determine their influence on the soil properties and productivity of spring oats (Avena sativa L.). The biomass of the aboveground part of cover crop mixtures of different botanical compositions varied from 2.33 to 2.67 Mg ha−1. As the diversity of plant species in cover crop mixtures increased, the accumulation of nutrients in the aboveground part biomass increased, and the risk of nutrient leaching was reduced. The post-harvest cover crop mixture TGS GYVA 365, consisting of eight short-lived and two perennial plant species, significantly reduced the mineral nitrogen content in the soil in spring and had the strongest positive effect on organic carbon content. Post-harvest cover crop mixtures TGS GYVA 365 and TGS D STRUKT 1 did not affect the content of available potassium in the soil but significantly reduced the content of available phosphorus. All tested cover crop mixtures, including the undersown TGS BIOM 1 and the post-harvest mixtures TGS D STRUKT 1 and TGS GYVA 365, reduced soil shear strength and improved soil structure, although the reduction was not statistically significant for TGS D STRUKT 1. Cover crop mixtures left on the soil surface as mulch had a positive effect on the chlorophyll concentration in oat leaves, number of grains per panicle, and oat grain yield. A significant positive correlation was found between oat grain yield and several yield components, including crop density, plant height, number of grains per panicle, and grain mass per panicle. These findings highlight the potential of diverse cover crop mixtures to reduce fertilizer dependency and improve oat productivity under temperate climate conditions.

Torrefaction of sewage sludge: An approach to nutrient recycling and contaminant reduction in agriculture.

Soil is an important basic natural resource in human production and life. Studying the micro-structure of soil, understanding various types of soil and grasping its specific data are of great guiding significance and reference value for the growth and development of plants and crops. Therefore, the systematic classification of soil is particularly important. There is no study on Soil Taxonomy in Renhe District of Panzhihua City, so this study will make up for this gap.The soil samples of 8 towns and townships in Renhe District of Panzhihua City were collected and analyzed. The main nutrient components were soil water content, soil ammonium nitrogen, soil available phosphorus, soil effective potassium, soil organic matter and soil pH value. The characteristics of soil were obtained through data analysis, and the soil types in the study area were also analyzed. Types were named and classified. Complete the task of land resources survey in Renhe District, clarify the types and distribution of soil in Renhe District, and enrich the content of soil science. The nutrient contents of various soils were analyzed by laboratory tests, which provided scientific basis for soil classification.Through the analysis of experimental data, it is found that the soil water content in Renhe District is low, the soil is weak alkaline, the content of organic matter is generally high, the content of ammonium nitrogen is low, the content of available phosphorus is generally high, and the content of effective potassium is relatively low

Forest fires are one of the significant factors affecting forest ecosystems globally, with their impacts on soil microbial community structure and function drawing considerable attention. This study focuses on the short-term effects of different fire intensities on soil bacterial community structure and function in Abies (Pinus densata) forests within the Birishen Mountain National Forest Park in southeastern Tibet. High-throughput sequencing technology was employed to analyze soil bacterial community variations under unburned (C), low-intensity burn (L), moderate-intensity burn (M), and high-intensity burn (S) conditions. The results revealed that with increasing fire severity, the dominant phylum Actinobacteriota significantly increased, while Proteobacteria and Acidobacteriota markedly decreased. At the genus level, the relative abundance of Bradyrhizobium declined significantly with higher fire severity, whereas Arthrobacter exhibited a notable increase. Additionally, soil environmental factors such as available phosphorus (AP), dissolved organic carbon (DOC), C/N ratio, and C/P ratio displayed distinct trends: AP content increased with fire severity, while DOC, C/N ratio, and C/P ratio showed decreasing trends. Non-metric Multidimensional Scaling (NMDS) analysis indicated significant differences in soil bacterial community structures across fire intensities. Diversity analysis demonstrated that Shannon and Simpson indices exhibited regular fluctuations correlated with fire severity and were significantly associated with soil C/N ratios. Functional predictions revealed a significant increase in nitrate reduction-related bacterial functions with fire severity, while nitrogen-fixing bacteria declined markedly. These findings suggest that forest fire severity profoundly influences soil bacterial community structure and function, potentially exerting long-term effects on nutrient cycling and ecosystem recovery in forest ecosystems.

The restoration of technogenically-disturbed territories represents one of the most critical ecological and forestry challenges, particularly in regions with a high degree of anthropogenic impact, such as the Ural region. This study ex-plores the possibility of using amorphous silica as a fertilizer to increase the efficiency of forest ecosystem recovery on reclaimed lands. Amorphous forms of silica exhibit multifunctionality and can exert both direct impacts on plant resili-ence to various stresses and indirect influences by improving soil properties and enhancing its fertility. The objective of this investigation is to evaluate the effect of amorphous silica on the growth of Scots pine (Pi-nus sylvestris L.) and Siberian spruce (Picea obovata Ledeb.) seedlings in a reclaimed granite quarry. To accomplish this, sites were chosen within the educational-experimental polygon for land reclamation of disturbed lands at the Ural State Forest Engineering University, situated at the Isetsk granite quarry in the Sverdlovsk region. The soil analysis revealed a moderate soil acidity level (pH 4.92±0.12) and low concentrations of water-soluble potassium and nitrate nitrogen in the soils of the reclaimed site, along with a relatively elevated content of available phosphorus. These findings suggest the need for applying fertilizers and soil amendments during the establishment of forest plantations. As part of the study, works were carried out on the application of amorphous silica, as well as an analysis of its effect on the growth of tree seedlings. The findings from this research will broaden our comprehension of the efficacy of silicon-based fertilizers under forestry reclamation conditions and propose novel strategies for restoring ecosystems in technogenically disturbed areas

Microbial remediation technology has the characteristics of high efficiency and environmental protection, which has attracted attention. However, there is complexity in the microorganism-soil-plant system. The effects of microbial agents on soil nutrients, plant quality, rhizosphere, and endophytic microorganisms are still unclear. Here, we demonstrate the application of Bacillus megaterium NCT-2 as a multifunctional agent that concurrently addresses salinization-driven nutrient imbalances and reshapes keystone microbial taxa to restore soil-plant homeostasis. The results showed that NCT-2 agent improved the soil nutrients, reduced the loss of nitrogen and sulfur, increased the content of available phosphorus, and decreased the electrical conductivity. The agent increased the number of bacteria and fungi in the soil. Meanwhile, NCT-2 agent improved the vegetable quality and yield. Specifically, the NCT-2 agent significantly increased the aboveground fresh weight, underground fresh weight, total flavonoids, antioxidant enzyme activity, ascorbic acid, Cu, Zn, Fe, P, and K in lettuce, while significantly reduced nitrate. The chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll were significantly increased by the agent. Critically, high-throughput sequencing revealed NCT-2-driven enrichment of stress-resilient taxa (e.g., Firmicutes, Acidobacteria) and functional synergists (e.g., Acetobacter), which correlated with soil nutrient fluxes and plant antioxidant capacity. By decoupling the interplay between microbial community restructuring and systemic remediation outcomes, this work establishes a novel framework for leveraging keystone taxa to optimize salinized agroecosystems.

Fritillaria taipaiensis P.Y. Li is commonly used in Chinese medicine for its cough-suppressing and expectorant properties. Due to over-excavation and ecological damage, the wild resources of F. taipaiensis have suffered serious damage. Understanding and improving the inter-root soil environment plays an important role in improving the success rate of artificial cultivation of F. taipaiensis and the quality of medicinal herbs. This study employed a pot experiment to inoculate three strains of phosphorus-solubilizing fungi from the Aspergillus genus for a total of seven treatment groups, with sterile physiological saline serving as the control group (CK). The research aims to examine the impact of inoculating phosphorus-solubilizing fungi on the biomass of F. taipaiensis, alkaloid concentration in its bulbs, and characteristics of the rhizosphere soil environment. The specific inoculation treatments included: Aspergillus tubingensis (Z1); Aspergillus niger (Z2); Aspergillus fumigatus (Z3); a combination of A. tubingensis and A. niger (Z12); a combination of A. niger and A. fumigatus (Z13); a combination of A. tubingensis and A. fumigatus (Z23); and a combination of all three fungi, A. tubingensis, A. niger, and A. fumigatus (Z123). Inoculation with phosphorus-soluble fungi significantly increased the biomass of F. taipaiensis, and the largest increase was in the Z123 group, which was 62.85% higher than that of the CK group. Total alkaloid content increased the most (0.11%) in the Z3 group, which was an 83.87% increase compared with the CK group. The total content of monomer alkaloids in the Z3, Z13, and Z123 groups increased by 10.53%, 12.48%, and 9.61%, respectively, compared with those in the CK group, indicating that the quality of F. taipaiensis could be significantly improved after applying phosphorus-solubilizing fungi. The soil environment improved after inoculation with different phosphorus-solubilizing fungi. The Z23 and Z123 groups had the greatest effect on the rhizosphere soil bacteria and Actinomyces. Overall, the soil nutrient content of the Z13 group increased the most, and the contents of available phosphorus, available potassium, available nitrogen, total phosphorus, and organic matter increased by 47.71%, 27.36%, 26.78%, 25.13%, and 31.72%, respectively, compared with those in the CK group. These results show that the treatment groups that included different combinations of strains were superior to the single-strain treatment groups, and the Z123 group was the best treatment group when considering bulb biomass and alkaloid and soil nutrient contents. Applying phosphorus-solubilizing fungus fertilizer is highly feasible during F. taipaiensis production in the field.

In northern China, intercropping soybeans with forage mulberry (Morus alba L.) enhances soybean yields through the optimization of natural resource use. However, the mechanisms underlying these improvements remain largely unknown. The aim was to explore the effects of this intercropping on soybean growth and yield. We used transcriptomics, redundancy analysis, and structural equation modeling to evaluate soybean growth, yield, and nodulation; results showed that intercropping did not adversely affect plant height or stem diameter but increased chlorophyll content, photosynthetic rate, leaf area, and yield of soybean. It also increased soil available phosphorus, soil available potassium and soil water content, while reducing soil available nitrogen and the pH value. It promoted P and organic acid metabolism, transporter activity, and key-gene expression. Redundancy analysis strikingly reveals that intercropping is positively correlated with yield, gene expression and soil properties. Meanwhile, structural equation modeling analysis demonstrates that the content of available phosphorus, available potassium, and water in rhizosphere soil are positively correlated with soybean nodulation. Additionally, nodulation traits can directly enhance nitrogen metabolism, which subsequently boosts photosynthesis and ultimately exerts an indirect positive influence on soybean yield. Furthermore, intercropping soybeans with forage mulberry did not induce shade stress on the above-ground portion of soybeans but promoted its growth and nodulation.

BACKGROUND: According to modern concepts, the SWEET family may be the only family of plant sugar transporters that includes genes specifically expressed during the formation and development of plant symbiosis with fungi of arbuscular mycorrhiza. The data on the key genetic markers of the development of effective arbuscular mycorrhiza symbiosis can contribute an active development of organic agriculture in various conditions of phosphorus availability in the soil. AIM: to evaluate the effect of arbuscular mycorrhiza on the expression of SWEET genes in M. lupulina L. during key stages of host plant development (stages of leaves rosette, stooling initiation, stooling, lateral branching initiation, lateral branching and flowering). MATERIALS AND METHODS: The study was performed using a highly efficient plant-microbial system “Medicago lupulina + Rhizophagus irregularis” grown under conditions with a high content of available phosphorus in the substrate. RESULTS: Under condition of high phosphorus level in the substrate it was shown for the first time the MlSWEET1b and MlSWEET3c genes in M. lupulina leaves were characterized by specific expression during mycorrhization. CONCLUSIONS: MlSWEET1b and MlSWEET3c and their orthologs can be considered as marker genes of effective symbiosis development, as a tool of biotechnology to increase agricultural productivity with using biostimulants based on arbuscular mycorrhiza fungi.

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is one of the main afforestation tree species in southern China. Continuous planting for multiple generations has led to a decrease in the content of available phosphorus in the soil. To adapt to low phosphorus stress, plants develop a series of physiological, biochemical, and developmental responses through self-regulation. Recent studies have shown that miRNAs play a regulatory role in plants' responses to low phosphorus stress. However, the regulatory mechanism of miRNAs in Chinese fir in response to low phosphorus stress is still unclear. Here, we performed small RNA sequencing on the Chinese fir roots treated with normal phosphorus and low phosphorus and identified a total of 321 miRNAs, including 139 known miRNAs and 182 new miRNAs, with 43 differentially expressed miRNAs (DEMs). Integrative analysis combined with degradome sequencing data revealed that 193 miRNAs (98 known and 95 new) targeted 469 genes, among which 23 DEMs targeted 44 genes. Gene enrichment analysis indicated that under low phosphorus stress, transcription and transcriptional regulation, as well as signal transduction, were significantly activated in Chinese fir. Modules in the miRNA-target pathways, such as miR166/HD-ZIP III, miR169/NFYA7, miR529/SPL, and miR399/UBC23, may be the key regulatory factors in the response to low phosphorus stress in Chinese fir. In addition, we found that PC-3p-1033_8666 was significantly downregulated and that PC-5p-3786_2830 was significantly upregulated, which presumably respond to low phosphorus stress by indirectly affecting phosphorus-related hormone signaling or PSR genes. The identified miRNA-target network and significantly activated pathways in this study provide insights into the post-transcriptional regulatory mechanisms of Chinese fir adapting to low phosphorus environments, which can offer theoretical references for the stress resistance and superior variety breeding of Chinese fir.

Abstract The research included the isolation and identification of Azotobacter bacteria (Azotobacter chroococcum and Azotobacter paspali) using traditional methods, with molecular diagnosis of the type Azotobacter chroococcum and studying the effect of these two types of bacteria with different types of organic manure (Sheep, Buffalo, Poultry) on some soil properties (Soil moisture content, Degree of soil interaction(PH), Electrical conductivity of soil(EC), Soil content of organic matter, organic carbon and available phosphorus). The results of the molecular identification of Azotobacter chroococcum bacteria using the PCR device showed the appearance of bands of 811 bp for this bacteria. The results of the sequencing of the Azotobacter chroococcum bacteria isolates showed that they were 99% similar to the Azotobacter chroococcum bacteria found in the GenBank database (NCBI). The results of the phylogenetic tree analyses showed that the Azotobacter chroococcum bacteria isolates are closely related phylogenetically to Azotobacter chroococcum bacteria By giving it a 99.11% - 99.12% similarity with isolates of the Azotobacter chroococcum bacteria isolated from several countries in the world. The effect of fertilization with Azotobacter bacteria and organic manure was significant on most of the studied soil properties. The bacterial type Azotobacter chroococcum gave the highest values in soil moisture content, soil content of organic matter and organic carbon and the lowest values for soil reaction degree in association with Azotobacter paspali bacteria, the two types of bacteria did not affect the reduction of soil electrical conductivity. As for the soil content of available phosphorus, the type Azotobacter paspali gave the highest value in it. The Buffalo manure treatment gave the highest values in the soil moisture content, soil content of organic matter, organic carbon and available phosphorus and reduced soil reaction degree compared to the control treatment. The sheep manure treatment gave the lowest value for soil electrical conductivity with a significant increase compared to the control treatment.