Improvement Of Nitrogen Fixation Research Articles

Exploring the potential of ChatGPT in enhancing atmospheric pressure plasma research techniques

AbstractReleased in March 2023, GPT‐4 has shown remarkable proficiency in various scientific areas, including atmospheric pressure plasma research. The paper discusses how GPT‐4, supported by ScholarAI and Wolfram plugins, enhances research efficiency with its vast knowledge and inferencing skills. It focuses on plasma‐water‐based nitrogen fixation experiments, demonstrating GPT‐4's abilities in explanation, analysis, prediction, planning, and verification. The study also addresses challenges like interpreting non‐textual data and keeping pace with scientific advancements. It highlights GPT‐4's role in improving nitrogen fixation process efficiency, showcasing its utility in scientific analysis and decision‐making. The paper emphasizes the evolving role of AI in research and the need for the scientific community to adapt to the rise of more advanced AI systems.

Pseudomonas chlororaphis IRHB3 assemblies beneficial microbes and activates JA-mediated resistance to promote nutrient utilization and inhibit pathogen attack.

The rhizosphere microbiome is critical to plant health and resistance. PGPR are well known as plant-beneficial bacteria and generally regulate nutrient utilization as well as plant responses to environmental stimuli. In our previous work, one typical PGPR strain, Pseudomonas chlororaphis IRHB3, isolated from the soybean rhizosphere, had positive impacts on soil-borne disease suppression and growth promotion in the greenhouse, but its biocontrol mechanism and application in the field are not unclear. In the current study, IRHB3 was introduced into field soil, and its effects on the local rhizosphere microbiome, disease resistance, and soybean growth were comprehensively analyzed through high-throughput sequencing and physiological and molecular methods. We found that IRHB3 significantly increased the richness of the bacterial community but not the structure of the soybean rhizosphere. Functional bacteria related to phosphorus solubilization and nitrogen fixation, such as Geobacter, Geomonas, Candidatus Solibacter, Occallatibacter, and Candidatus Koribacter, were recruited in rich abundance by IRHB3 to the soybean rhizosphere as compared to those without IRHB3. In addition, the IRHB3 supplement obviously maintained the homeostasis of the rhizosphere microbiome that was disturbed by F. oxysporum, resulting in a lower disease index of root rot when compared with F. oxysporum. Furthermore, JA-mediated induced resistance was rapidly activated by IRHB3 following PDF1.2 and LOX2 expression, and meanwhile, a set of nodulation genes, GmENOD40b, GmNIN-2b, and GmRIC1, were also considerably induced by IRHB3 to improve nitrogen fixation ability and promote soybean yield, even when plants were infected by F. oxysporum. Thus, IRHB3 tends to synergistically interact with local rhizosphere microbes to promote host growth and induce host resistance in the field.

Research on key influencing factors and mechanisms of improved nitrogen fixation efficiency in magnetic-driven gliding arc

Gliding arc is considered to be an efficient method for nitrogen fixation. In this study, an improved magnetic-driven rotating gliding arc method was adopted to investigate the effects of gas flow rate, current, magnetic field, nitrogen-to-oxygen ratio in the working gas, and relative humidity on nitrogen fixation efficiency. To further understand the relationship between the discharge mechanism and nitrogen fixation efficiency, the arc length, arc diameter, arc rotation frequency, and reaction pathway were studied to find the relationship between external parameters, discharge characteristics, and nitrogen fixation efficiency. The research results indicate that the discharge current and magnetic field not only change the rotation frequency of the gliding arc, but also affect its length and diameter, and the amount of ionizing gases involved in the working gas, thus affecting nitrogen fixation efficiency. When the nitrogen volume ratio in the feed gas is 60%, the lowest energy cost can be achieved, which is 18.6% lower than that of air. The energy cost of nitrogen fixation is closely related to the humidity of the air. As the humidity increases, the energy cost also increases. At the magnetic field strength of 160 mT, gas flow rate of 10 l min−1, and current of 40 mA, the energy cost of 1.708 MJ mol−1 is realized which is the current lowest for plasma nitrogen fixation in this study.

Enhanced photocatalytic nitrogen fixation on Cu2O clusters/MIL-100(Fe) heterojunction

A series of Cu2O clusters/MIL-100(Fe) heterojunctions with different Cu2O mass ratios were constructed as the photocatalysts for N2 fixation. An optimal nitrogen fixation performance of 51.22 μmol·g−1·h−1 is achieved when the mass fraction of Cu2O is 20 %. Isotope analysis experiments confirmed that the nitrogen source is N2. Possible intermediate signals during photocatalytic reactions were detected by in situ DRIFTS. XPS results further confirm the formation of Cu2O/MIL-100(Fe) heterojunctions, and that the existence of Cu–O surface interactions is the key to efficient electron transfer. It is revealed that the improvement of the catalytic performance is derived from the formation of heterojunction which regulates the energy band structure as well as promotes the separation of photogenerated electron-hole pairs. This study proposes a possible mechanism of photocatalytic nitrogen fixation and emphasizes the role of surface interaction and electron transfer in type-II heterojunction in improving nitrogen fixation performance.

Subsoiling tillage increased core microbiome associated with nitrogen fixation in the fallow season under rainfed maize monoculture

Subsoiling tillage (ST) is a promising agronomy practice to improve soil physicochemical properties, soil microbial diversity during the crop growing season, and ultimately crop yield, but little is known about whether and how the ST practice will impact soil physicochemical properties and microbial communities in fallow season and their impacts on crop growth in next season. Here, a four-year continuous field experiment was conducted to compare the impacts of three tillage treatments, i.e., the ST, the no-tillage (NT), and the rotary tillage (RT), on soil physicochemical properties and microbial communities in maize fallow season. The results showed that compared with the RT treatment, the ST treatment improved maize yield by 2.3%, 4.2%, 11.4%, and 9.7% from 2018 to 2021, respectively, while there was no significant yield loss between the NT and RT. The ST treatment improved root biomass and soil available nitrogen by 25.1% and 34.0%, respectively, but scarcely impacted soil bulk density and water-filled pore space in comparison with the RT treatment in the maize fallow season in 2021. In addition, changes in root biomass further altered soil bacterial core microbiomes. Compared with the RT treatment, the ST treatment increased the relative abundance of core microbiomes related to nitrogen fixation and denitrification by 169.5% and 62.0%, respectively, but reduced the relative abundance of core microbiomes related to nitrification by 39.0%. The potential functional profile of core microbiomes predicted by the FAPROTAX database also showed that the ST treatment significantly improved nitrogen fixation and ureolysis by 115.9% and 346.9%, respectively, while decreased nitrification by 57.1% in comparison with the RT treatment. The results of the structural equation model showed that ST-induced changes in the function of nitrogen fixation improved soil available nitrogen content in the maize fallow season, which could supply nutrients for maize growth in the next growing season. Additionally, although the NT treatment improved microbial diversities in comparison with the RT and ST treatments, it reduced the relative abundance of microbiomes related to nitrogen cycling in the maize fallow season. These results indicate that the subsoiling tillage could increase the abundance of core microbiomes related to nitrogen fixation and mineralization, which increase soil available nitrogen content in the fallow season of maize cropping in the northeast of China.

English

Millets are becoming popular due to special features of high nutrition, low inputs, and climate resiliency. While major crops like wheat, rice & maize are exhaustive, resource-loving, and susceptible. There is a need for crop diversification & potential millets to be adapted for sustainability. Faisalabad is the grain belt of Punjab, Pakistan, but only one millet crop, pearl millet, is being cultivated for grain purposes. An alternate crop, foxtail millet study was designed, and 200 exotic accessions of different origins were acquired from the USDA. Germination behavior at optimal controlled temperatures (18 °C, 25°C, 32°C, and 39 °C) was tested, best germination was observed at 32 °C, and 135 out of 200 accessions germinated at ≥80%. These accessions were initially screened for germination strength (G%, G50, MGT, U, GI, Z, and CVG), seedling vigor (SL, RL, SFW, SDW), and preliminary yield tests in the greenhouse, then evaluated under three different field locations of varied soil environments. Principle component analysis (PCA) was performed, and 14 clusters of accessions were sorted out using hierarchical clustering. The high-yielding accessions were selected from each cluster and sown at three different locations/soil environments in the Faisalabad, i.e., 1- ARA, UAF (fertile, low irrigated), 2= DFP, UAF (salt-affected soil), 3= JKA, CJF (fertile, well-irrigated). Results were statistically analyzed & graphically represented using project R for statistical computing. Accessions A73-IN and A101-IN produced the highest grain yield of 3504 kg ha-1 and 2667 kg ha-1 respectively, and a biomass accumulation of 8 t ha-1 at the location JKA, CJF. Yield-related results under low irrigation & saline soil were also significant, however, overall, 69% of yield was reduced in the saline and 67% in low irrigated fields. It was concluded that accessions of Indian origin may be adapted under Faisalabad climate and an additional inquiry into abiotic stresses is required to discover suitable genotypes

Identifying the specific pathways to improve nitrogen fixation of different straw biochar during chicken manure composting based on its impact on the microbial community

The application of straw biochar to chicken manure composting mitigated nitrogen loss. However, the impact of biochar derived from different types of straw on nitrogen fixation in chicken manure composting is discrepant, and the specific pathways remain unclear. Therefore, this study aimed to clarify the specific pathways of maize straw biochar (M) and rice straw biochar (R) to improve nitrogen fixation during chicken manure composting. The nitrogen losses in control (no addition, CK), M, and R composting were 51.84 %, 33.47 %, and 38.24 %, respectively, suggesting that adding straw biochar effectively improved nitrogen fixation. Microbial community analysis suggested that inhibiting denitrification and NH4+-N transformation by microorganisms was the primary means of improving nitrogen fixation. Meanwhile, biochar addition reduced the number of bacteria participating in nitrogen transformation and strengthened the NO3–-N and total organic nitrogen transformation processes, among which the effect of M composting was stronger. The stronger effect was attributed to the significant role of the core microorganisms in M composting in shifting the transformation processes of the nitrogen components (P < 0.05). Therefore, the function of different straw biochar was determined by its different impacts on the microbial community, highlighting the important role of microbial community variability.

Belowground facilitation of plant mixtures on rhizosphere soil of Commelina communis grown on extremely Cu- and Cd-contaminated mine: From soil quality to bacterial community

Plant–plant interactions exert positive effects under stress conditions, but their impact on heavy metal-contaminated rhizosphere soil quality and bacterial community remains unclear. In this work, the rhizospheric soil of Cu-accumulator Commelina communis and neighboring plants grown in a heavily contaminated copper mine was analyzed to elucidate such belowground facilitation. Physicochemical properties and microbial characteristics of rhizospheric soil of control C. communis (far from neighboring plants), facilitated C. communis (near neighboring plants), and neighboring plants were compared. The average values of total organic carbon, NH4+-N, NO2−-N, NO3−-N, available phosphorus, urease, and phosphatase in the C. communis rhizosphere increased by 0.82-, 0.64-, 0.44-, 0.06-, 0.10-, 0.36-, and 0.30-fold in the presence of surrounding plants, respectively. The relative abundance of oligotrophic bacteria (Chloroflexi) decreased, whereas copiotrophic bacteria (Proteobacteria) increased in plant species mixtures. Venn graph and partial least squares discriminant analysis indicated that the composition of the bacterial community in the facilitated C. communis rhizosphere showed higher similarity to neighboring plants than to control C. communis. Among 49 predicted functional groups analyzed by FAPROTAX analysis, chemoheterotrophy (36.04 %) involved in carbon cycles had the highest relative abundance and increased in the facilitated C. communis rhizosphere due to the positive response of 193 OTUs (mainly belonging to Proteobacteria and Actinobacteriota) under plant–plant interactions. The increased relative abundance of Methylocella and Bradyrhizobium resulted in improved nitrogen fixation in the C. communis rhizosphere, whereas nitrate reduction with its main performer Rubrobacter was inhibited. The ecological function of rhizobiomes of the facilitated C. communis and neighbors also showed higher similarity compared with that of the control C. communis. These results show the role of neighboring plants in modulating soil quality and rhizobiomes of plant remediators under stress and more indoor garden experiments need to be conducted to verify such belowground facilitation.

Post-Tin-Mining Agricultural Soil Regeneration Using Local Organic Amendments Improve Nitrogen Fixation and Uptake in a Legume–Cassava Intercropping System

The low nitrogen content of Bangka Island’s post-tin-mining soil may limit its suitability for agricultural production. In this study, we investigated the effect of locally available organic soil amendments on nitrogen fixation (N2–fixation) and crop nitrogen (N) uptake in a cassava–legume intercrop system. Cassava was intercropped with centrosema in post-tin-mining soils with six treatments, including a control and different soil amendments, such as dolomite, compost, charcoal, a combined treatment of charcoal and compost, and a combined treatment of compost and sawdust. The percentages of N derived from N2-fixation (%Ndfa) with the different seasons and treatments were comparable. Nonetheless, due to the higher shoot biomass accumulation, the mass of N2–fixation in soil amended with compost and when combined with charcoal was significantly higher than the control (50 to 73 kg ha−1). Treatments with compost and its combination with charcoal exhibited higher N uptake from the cassava–centrosema intercropped system (82 and 137 kg ha−1) and higher inorganic ammonium (NH4+) concentrations in the soil at harvest time (5.5 and 6.7 µg g−1). When combined with organic soil amendments, N2–fixation from centrosema produces not only higher biomass, but also higher N contribution to the system. Overall, locally available organic amendments, particularly the combined application of charcoal and compost, showed promise for improving N2–fixation of intercrop centrosema as well as for increasing N availability in the soil, which is of critical importance for crop growth in post-mining soils that have lost fertility.

A transcription factor of the NAC family regulates nitrate-induced legume nodule senescence.

Legumes establish symbioses with rhizobia by forming nitrogen-fixing nodules. Nitrate is a major environmental factor that affects symbiotic functioning. However, the molecular mechanism of nitrate-induced nodule senescence is poorly understood. Comparative transcriptomic analysis reveals an NAC-type transcription factor in Lotus japonicus, LjNAC094, that acts as a positive regulator in nitrate-induced nodule senescence. Stable overexpression and mutant lines of NAC094 were constructed and used for phenotypic characterization. DNA-affinity purification sequencing was performed to identify NAC094 targeting genes and results were confirmed by electrophoretic mobility shift and transactivation assays. Overexpression of NAC094 induces premature nodule senescence. Knocking out NAC094 partially relieves nitrate-induced degradation of leghemoglobins and abolishes nodule expression of senescence-associated genes (SAGs) that contain a conserved binding motif for NAC094. Nitrate-triggered metabolic changes in wild-type nodules are largely affected in nac094 mutant nodules. Induction of NAC094 and its targeting SAGs was almost blocked in the nitrate-insensitive nlp1, nlp4, and nlp1 nlp4 mutants. We conclude that NAC094 functions downstream of NLP1 and NLP4 by regulating nitrate-induced expression of SAGs. Our study fills in a key gap between nitrate and the execution of nodule senescence, and provides a potential strategy to improve nitrogen fixation and stress tolerance of legumes.

English

Nitrogen is essential due to its function in plant growth and development. It is a component of DNA and proteins which are the building blocks of life. Nitrogen is one of the most limiting factors for crop production. The need to meet the huge nitrogen requirement has necessitated the use of synthetic fertilizer. However, its continued application affects soil health, environment, and agricultural sustainability. Identifying breeding lines and developing new varieties that can efficiently fix atmospheric nitrogen and integrating these varieties into farming systems is one of the best alternatives. Field experiment was conducted at the Savanna Agricultural Research Institute research fields using 20 elite soybean lines under rain fed conditions. The objective was to select soybean (Glycine max) lines for improved nitrogen fixation, water use efficiency and grain yield. Randomized complete block design was used with three replications. Data collected were the amount of nitrogen fixed, nitrogen derived from the atmosphere, and grain yield. Genotypes showed significant variability in the amount of N-fixed, percent nitrogen derived from the atmosphere and grain yield. The mean symbiotic N contribution by the genotypes ranged from 53.6 kg/ha &ndash; 370.5 kg/ha. Grain yield was significantly different among the genotypes. Five genotypes showed superior performance for N-fixed and grain yield. There was high heritability, Phenotypic Coefficient of Variation and Genotypic Coefficient of Variation for the selected traits, which is required in breeding program for crop improvement. Genotypes should be re-evaluated in multi-locations to confirm performance and stability for release as varieties. Key words:&nbsp; Glycine max, genotypes, heritability, genotypic coefficient of variation, phenotypic coefficient of variation.

Genetic engineering for enhanced biological nitrogen fixation in cereal crops

Enhancing biological nitrogen (N) fixation in cereal crops has been a long-sought objective. Recently, Yan et al. identified plant compounds that induce biofilm production of diazotrophic bacteria and then performed genetic engineering in order to improve nitrogen fixation in rice plants. These findings hold promise for sustainable agriculture.

The potential of conservation agriculture to improve nitrogen fixation in cowpea under the semi-arid conditions of Kenya

Low-cost but productive crop intensification options are needed to assist smallholder farmers in the tropics to move away from poverty. This study assessed the capacity of cowpea (Vigna unguiculata (L.) Walp.) to perform biological N fixation (BNF) under no-tillage practices, crop residue cover and intercropping with maize (Zea mays L.). The study was performed during the long rains of 2017 at Kiboko experimental station, located in semi-arid eastern Kenya. The research field trials had been running for three years (6 cropping seasons) by the time the sampling took place. The experimental set up was a split-plot design: main plots being tillage system (no till + maize stover retention (CA), and conventional tillage to 15 cm depth without mulch retention (CT)), sub-plot being cropping system (maize-cowpea intercrop, maize monocrop, and cowpea monocrop). Cowpea plants were sampled at 50% flowering stage and at physiological maturity to investigate biomass production and %N derived from the atmosphere (%Ndfa) through the 15N natural abundance technique, using maize as a reference control. Results showed that the number of nodules per plant was higher in CA treatments rather than in CT although not significant (p&amp;gt;0.05). Mean cowpea grain yield at harvest varied between 472 – 590 kg ha‐1 in intercrops whereas grain yield in monocrops was between 1465 - 1618 kg ha-1. Significant differences were however recorded between treatments with CT monocropped cowpea at flowering recording the highest mean %Ndfa (62%) and CT intercrop the lowest (52%). At harvest stage CA inter recorded the highest %Ndfa (54%) while CT intercrop the lowest (41%). The %Ndfa was higher (p&amp;lt;0.05) at flowering (between 57- 69%) compared with 45 - 64 % at harvest stage. Overall cowpeas in intercrops derived between 17.8 - 22.8 kg ha-1 of their total N from atmospheric dinitrogen fixation while monocrops between 54.9 - 55.2 kg ha-1. The effect of CA on BNF was positive but not significantly different from CT. These results suggest that CA has the potential to enhance the BNF process but there is a need to explore in future alternative spatial arrangement and variety choice in intercropping of cowpea and maize to optimize the BNF process.

Prospects of rhizobial inoculant technology on Bambara groundnut crop production and growth

After peanuts and cowpeas (Vigna unguiculata), the Bambara groundnut (Vigna subterranea (L.) Verdc) is the third most significant food legume in Africa. It is characteristically grown in marginal soils, is drought tolerant, and also has the potential for nitrogen fixation. Despite that, year-on-year Bambara groundnut yields are on a gradual decline due to a combination of abiotic and biotic stresses such as uneven annual rainfall and climate-induced changes in soil microbial community compositions, negatively impacting food security. Thus, the application of rhizobial inoculants at planting significantly improves yields in many leguminous crops. Moreover, symbiotic inoculants are well established in developed countries for improving nitrogen fixation and productivity in grain legumes. Sub-Saharan African countries, however, still under-utilise the above practice. In crop production, nitrogen (N) is the most frequently deficient nutrient since it stimulates root and shoots growth. Whereas nitrogen fertilisers can be used to supplement soil N levels, they are, however, also costly, at times inadequate, may not be timely in supply and may have deleterious environmental consequences. Hence, rhizobial inoculants are seen as a cheaper, easier, and safer method for improving N-fixation and crop productivity in grain legumes, as a result, smallholder farming systems are food secure. Thus, identifying the most efficient rhizobial strains for biofertiliser production for Bambara groundnut is of utmost importance to the farming communities.

Deciphering the role of SPL12 and AGL6 from a genetic module that functions in nodulation and root regeneration in Medicago sativa

Key messageOur results show that SPL12 plays a crucial role in regulating nodule development in Medicago sativa L. (alfalfa), and that AGL6 is targeted and downregulated by SPL12.Root architecture in plants is critical because of its role in controlling nutrient cycling, water use efficiency and response to biotic and abiotic stress factors. The small RNA, microRNA156 (miR156), is highly conserved in plants, where it functions by silencing a group of SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors. We previously showed that transgenic Medicago sativa (alfalfa) plants overexpressing miR156 display increased nodulation, improved nitrogen fixation and enhanced root regenerative capacity during vegetative propagation. In alfalfa, transcripts of eleven SPLs, including SPL12, are targeted for cleavage by miR156. In this study, we characterized the role of SPL12 in root architecture and nodulation by investigating the transcriptomic and phenotypic changes associated with altered transcript levels of SPL12, and by determining SPL12 regulatory targets using SPL12-silencing and –overexpressing alfalfa plants. Phenotypic analyses showed that silencing of SPL12 in alfalfa caused an increase in root regeneration, nodulation, and nitrogen fixation. In addition, AGL6 which encodes AGAMOUS-like MADS box transcription factor, was identified as being directly targeted for silencing by SPL12, based on Next Generation Sequencing-mediated transcriptome analysis and chromatin immunoprecipitation assays. Taken together, our results suggest that SPL12 and AGL6 form a genetic module that regulates root development and nodulation in alfalfa.

A Ce-UiO-66 Metal-Organic Framework-Based Graphene-Embedded Photocatalyst with Controllable Activation for Solar Ammonia Fertilizer Production.

Currently, nitrogen fertilizers feed half of the global population, but their use is limited by energy consumption and transportation. Therefore, it is important to study photocatalysts for use in solar nitrogen fertilizers. Herein, a new type of graphene-embedded Ce-based UiO-66 (Ce-UiO-66) photocatalyst (GSCe) is investigated. Ce-UiO-66 is activated by the breakage of benzene-C bonds and the formation of active sites by ultraviolet light in water. Moreover, embedding graphene effectively controls activation and improves nitrogen fixation. GSCe exhibited a remarkable apparent quantum efficiency (AQE) of 9.25 % and stability under 365 nm light with solar-level intensity. GSCe also performed well as a solar ammonia fertilizer for crop cultivation. This investigation opens up opportunities for nitrogen fixation photocatalysts to be used as environmentally friendly solar nitrogen fertilizers.

A Ce‐UiO‐66 Metal–Organic Framework‐Based Graphene‐Embedded Photocatalyst with Controllable Activation for Solar Ammonia Fertilizer Production

AbstractCurrently, nitrogen fertilizers feed half of the global population, but their use is limited by energy consumption and transportation. Therefore, it is important to study photocatalysts for use in solar nitrogen fertilizers. Herein, a new type of graphene‐embedded Ce‐based UiO‐66 (Ce‐UiO‐66) photocatalyst (GSCe) is investigated. Ce‐UiO‐66 is activated by the breakage of benzene‐C bonds and the formation of active sites by ultraviolet light in water. Moreover, embedding graphene effectively controls activation and improves nitrogen fixation. GSCe exhibited a remarkable apparent quantum efficiency (AQE) of 9.25 % and stability under 365 nm light with solar‐level intensity. GSCe also performed well as a solar ammonia fertilizer for crop cultivation. This investigation opens up opportunities for nitrogen fixation photocatalysts to be used as environmentally friendly solar nitrogen fertilizers.

Halotolerant Plant Growth-Promoting Rhizobacteria Isolated From Saline Soil Improve Nitrogen Fixation and Alleviate Salt Stress in Rice Plants.

Salinity is one of the most damaging abiotic stresses due to climate change impacts that affect the growth and yield of crops, especially in lowland rice fields and coastal areas. This research aimed to isolate potential halotolerant plant growth-promoting rhizobacteria from different rhizo-microbiome and use them as effective bioinoculants to improve rice growth under salinity stress conditions. Bioassay using rice seedlings was performed in a randomized block design consisting of 16 treatments (control and 15 bacterial isolates) with three replications. Results revealed that isolates S3, S5, and S6 gave higher shoot height, root length, and plant dry weight compared with control (without isolates). Based on molecular characteristics, isolates S3 and S5 were identified as Pseudomonas stutzeri and Klebsiella pneumonia. These isolates were able to promote rice growth under salinity stress conditions as halotolerant plant growth-promoting rhizobacteria. These three potent isolates were found to produce indole-3-acetic acid and nitrogenase.

DYNAMICS OF SHEET SURFACE AREA OF PEAS DEPENDENCE DEPENDING ON VARIETY FEATURES, SOIL LIMITATION AND NUTRITIONAL SYSTEM

The article presents the results of research on the influence of varietal characteristics, soil liming, fertilizers on the formation of the leaf surface area. The use of microfertilizers Vuxal Extra CoMo for pre-sowing seed treatment, foliar fertilization with microfertilizers Vuxal Microplant during vegetative growth and Vuxal Calcium, Boron during budding provided against the background of control of increasing leaf area by increasing vegetative growth and surface growth rate -37% depending on the stage of plant development in vegetable varieties Skinado and Somerwood. Limeing also helped to increase the leaf surface area of plants from 2.5 to 7.8% depending on the phase of development, in our opinion due to the indirect effect on the reaction of soil solution and improving nitrogen fixation processes in the soil. The highest index of leaf surface of vegetable pea varieties was observed in the experimental variants, where against the background of control pre-sowing treatment of seeds with microfertilizer Vuxal Extra CoMo, foliar fertilization with microfertilizers Vuxal Microplant during vegetative growth and Vuxal Calcium, Boron, which changed from budding 1.15 to 1.17 in the Skinado variety and from 1.19 to 1.22 in the Somerwood variety. This was subsequently reflected in the indicators of the leaf index in the phase of flowering and bean formation. Leaf index in the phase of flowering and bean formation varied in Skinado variety from 1.58 to 1.59 and from 1.60 to 1.64.In the Somerwood variety in these phases, the leaf surface index was higher and varied from 1.64 to 1.68 in the flowering phase, and in the bean formation phase from 1.67 to 1.73. The content of chlorophyll in the leaves of vegetable peas largely depended on the phase of plant development, as well as the action of trace elements during seed treatment, foliar fertilization, and liming.

Rhizobium Symbiosis Leads to Increased Drought Tolerance in Chinese Milk Vetch (Astragalus sinicus L.)

Chinese milk vetch (Astragalus sinicus L.) is an important leguminous green manure that frequently suffers from seasonal drought. To improve its drought tolerance, the effects of rhizobia inoculation on drought tolerance and the underlying physiological mechanism were investigated. Drought tolerance in combination with nitrogen assimilation, free amino acids, and polyamines was investigated in milk vetch with active nodules (AN), with inactive nodules (LN), or without nodules (NN). AN plants had increased drought tolerance compared to LN and NN plants. Glutamine synthetase (GS), glutamine 2-oxoglutarate amino transferase (GOGAT), and glutamate dehydrogenase (GDH) activities were decreased after drought, with higher levels in AN plants than in LN and NN plants under both control and drought stress conditions. Higher levels of proline (Pro), arginine (Ala), alanine (Ala), and glutamate (Glu) were observed in AN plants compared with LN and NN plants. Putrescine (Put), spermidine (Spd), and spermine (Spm) levels were increased in response to drought, and higher levels of Put and Spd were maintained in AN plants. It is suggested that active nodulation leads to increased drought tolerance in milk vetch, which is associated with improved nitrogen fixation and ammonium assimilation, which in turn lead to the promotion of free amino-acid and polyamine synthesis.