Nodule Fresh Weight Research Articles

Effect of Seed Treatment of Boron, Cobalt and Molybdenum on Growth Parameter, Grain Yield and Seed Quality in Soybean (Glycine max L.)

This study aimed to evaluate the effect of seed treatment of boron, cobalt and molybdenum on growth parameter, grain yield and seed quality in soybean (Glycine max L.) during kharif, during July, 2022 at experimental farm, department of Soil Science and Agricultural chemistry, College of Agriculture, Badnapur. The experiment was laid out in Randomized Block Design (RBD) with 8 treatments which were replicated thrice.The treatments comprises (T1) Absolute control, (T2) RDF, (T3) RDF + Boron @ 2 gm kg-1 seed, (T4) RDF + Cobalt @ 1.5 gm kg-1 seed, (T5) RDF + Ammonium molybdate 1 gm kg-1 seed , (T6) RDF + Boron @ 2 gm kg-1 seed + Cobalt @ 1.5 gm kg-1 seed, (T7) RDF + Cobalt @ 1.5 gm kg-1 seed + Ammonium molybdate @ 1 gm kg-1 seed, (T8) RDF + Boron @ 2 gm kg-1 seed + Cobalt @ 1.5 gm kg-1 + Ammonium molybdate @ 1 gm kg-1 seed .To achieve the objectives the observations were recorded at various growth stages of soybean kharif, during 2022. The result indicates that, treatment (T8) receiving RDF + Boron @ 2 gm kg-1 seed + Cobalt @ 1.5 gm kg-1 seed + Ammonium molybdate @ 1 gm kg-1seed was found effective due to advantages effect on morpho-physiological growth, yield and yield attributing characters likeplant height, nodulation, fresh weight of nodules, no. of root nodules, root length, number of pods plant-1of soybean grain yield, Stover yield of soybean. In grain quality the results revealed that test weight, protein content percentage were significantly influenced with the application of treatment T8. On the other hand, in all the cases the lower response was found from the control treatment.

Evaluating the impact of phyto-hormones on the morpho-biochemical traits of soybean through seed treatment and foliar application

Global climate variations, mainly extreme temperatures reduce crop production and contributed to global food insecurity. Plant growth regulators (PGRs) improve physiological efficiency, photosynthetic capacity, and assimilate partitioning in field crops. However, their influence on soybean (Glycine max L.) yield and seed quality is under-researched. This study investigates the synergistic effects of auxin (2,4-D) and gibberellin (GA3) at 60 and 90 mg L−1 concentrations. This study investigates the impact of phytohormones, specifically gibberellic acid (GA3) and 2,4-dichlorophenoxyacetic acid (2,4-D), on the morphological and biochemical traits of soybean (Glycine max L.) through seed treatment and foliar application. These Growth regulators were applied through seed treatment at the time of sowing and foliar application at the time of flowering initiation stage. The experiment was designed using a RCBD arrangement and each block replicated thrice time. Seed treatment with 2,4-D at 90 mg/L showed that maximum plant height (116.80 cm), first node height (8.04 cm), No. of branches per plant (18.67), root length (18.12 cm) stem diameter (0.05 cm), no. of pods per plant (32.60), seed yield (1532.30 kg ha−1), biological yield (4109.30 ha−1), and harvest index (39.36 %). The GA3 (seed treatment) at conc. of 90 and 60 mg L−1 resulted in a significantly increased no. of nodule fresh weight, nodules per plant, and dry weight respectively. But the no. of seeds per pod did not showed significant results throughout the study. However, the foliar applied of 2,4-D at 90 mg L−1 resulted in significantly increased leaf area index (LAI) compared to the seed treatment. PGRs had a significant influence on quality traits. Thus, the application notably improved the potential of soybean and successful oilseed crop. Therefore, it is showed that using PGRs are extremely helpful for attaining higher growth, yield production, and improved quality of soybean.

Glycolipopeptide biosurfactant produced by Klebsiella pneumoniae ssp. ozaenae BK34: Virtue in germination and growth of chickpea (Cicer arietinum L.) HC-1 crop

Modern agriculture consumes many persistent and non-biodegradable agrochemicals enhancing production and economy for farmers. Besides, chemical surfactants are used as adjuvant to augment the action of agrochemicals. A toxicity concern of these agrochemicals and adjuvants on life forms and environment cannot be ignored. Microbiologically produced, eco-friendly, biodegradable surfactants could be suggested as an alternative, however, compatibility with plants and beneficial microflora needs to be ascertained before applying them into agriculture. The current study included evaluation of biosurfactant BS34 produced by Klebsiella pneumoniae BK34 towards germination and growth of chickpea [Cicer arietinum (L.)] seeds. The biosurfactant BS34 was characterized as surfactin like glycolipopeptide based on Fourier transform infrared spectroscopy and Liquid chromatography-Mass spectrometry characterization. The biosurfactant was found non-phytotoxic during in-vitro germination of chickpea seeds as evident from very high germination index of 187.74 as opposed to the almost negligible germination index of 0.04 shown by highly phytotoxic chemical surfactant. In comparison to control, the biosurfactant seed treatment [1%(w/v)] in an in-vivo study on chickpea increased the plant height by 18%, nodule number by 11.13%, nodule fresh weight by 12.66% shoot weight by 11.20% and root weight by 34.61%. Contrarily, seed treatment by 1% (w/v) sodium dodecyl sulfate (SDS) inhibited the germination and growth of chickpea seeds again documenting superiority of biosurfactants over their chemical counterparts. Improved seed germination, growth and yield attributes of chickpea crop in presence of non-phytotoxic glycolipopeptide biosurfactant produced by Klebsiella pneumoniae ssp. ozaenae BK34 suggests its potential as an alternative to chemical surfactants used in agriculture.

Interactive Effects of Boron and Molybdenum on Nodulation, Growth and Yield of Cowpea under South Gujarat Condition

Background: Cowpea seeds are nutritious component of human diet and being a legume crop, it also improves the soil fertility by increasing the amount of nitrogen in the soil through symbiotic nitrogen fixation. To study the effect of boron and molybdenum on nodulation, growth and yield of cowpea the field experiment was conducted at the Regional Horticultural Research Station, Navsari Agricultural University, Navsari, Gujarat, India, during summer season of 2019 and 2021. Methods: The experiment was carried out in a factorial randomized block design with 3 replications. Factor-1 consisted of four levels of seed treatments with molybdenum at 2 mg/l (M1), 4 mg/l (M2), 6 mg/l (M3) for 24 hours prior to sowing including control (M0), where as the second factor was consisted of four levels of boron (B) spray at 2 mg/l (B1), 4 mg/l (B2), 6 mg/l (B3) and control at 30 DAS, 45 DAS and 60 DAS with control. Boron was applied in the form of Boric acid and Molybdenum as ammonium molybdate. Result: The treatment combination of seed treatment of molybdenum @ 2 mg/ l with foliar spray of boron @ 4 mg/ l at 30, 45 and 60 DAS (M1B2) has significantly influenced yield parameters and registered maximum number of clusters per plant (6.50), green pod yield per plant (0.153 kg), green pod yield per net plot (3.98 kg), green pod yield per hectare (12.27 tonne). Seed treatment with different levels of molybdenum has significantly influenced nodulation in cowpea and recorded maximum number of nodules per plant (31.69 at final harvest) and fresh nodule weight (0.230 g/plant) in seed treatment of molybdenum @ 2 mg/ l (M2) among all the treatments at final harvest during all the years of study, including pooled analysis.

Relative multi-beneficial effect of MOs on plant health of chickpea (Cicer arietinum L. var. PG-186).

The phosphate solubilizing properties of Lysinibacillus macroides ST-30, Pseudomonas pelleroniana N-26, and Bacillus cereus ST-6 were tested for the chickpea crop of the Tarai region of Uttarakhand. These microbially inoculated plants have shown significant (p > 0.05) improvement in the plant health and crop health parameters, viz., root length, shoot length, fresh weight, dry weight, nodule number, nodule fresh weight, nodule dry weight, chlorophyll content, and nitrate reductase. The highest shoot length (46.10 cm) and chlorophyll content (0.57 mg g-1 fresh weight) were observed in ST-30 at 75 DAS with 20 kg P2O5/ha. Similarly, for plant P content, an increase of 90.12% over control was recorded in the same treatment. Treatments consisting of Lysinibacillus macroides ST-30 along with 20 kg/ha P2O5 were found to be most suitable as phosphatic fertilizer. Conclusively, sustainable agriculture practices in the Tarai as well as the field region may be developed based on a strategy of exploring microbial inoculants from the pristine region of the Western Himalayas. The presence and abundance of bacterial inoculants were confirmed through qRT-PCT. We conclude that the effective plant growth-promoting bacterium Lysinibacillus macroides ST-30 broadens the spectrum of phosphate solubilizers available for field applications and might be used together with 20 Kg/ha P2O5.

Combined dynamic transcriptome and flavonoid metabolome reveal the role of Mo nanoparticles in the nodulation process in soybean

Symbiotic nitrogen fixation can reduce the impact of agriculture on the environment by reducing fertilizer input. The rapid development of nanomaterials in agriculture provides a new prospect for us to improve the biological nitrogen fixation ability of leguminous crops. Molybdenum is an important component of nitrogenase, and the potential application of MoO3NPs in agriculture is largely unexplored. In this study, on the basis of verifying that MoO3NPs can improve the nitrogen fixation ability of soybean, the effects of MoO3NPs on the symbiotic nitrogen fixation process of soybean were investigated by using dynamic transcriptome and targeted metabolome techniques. Here we showed that compared with conventional molybdenum fertilizer, minute concentrations of MoO3NPs (0.01–0.1 mg kg−1) could promote soybean growth and nitrogen fixation efficiency. The nodules number, fresh nodule weight and nitrogenase activity of 0.1 mg kg−1 were increased by 17 %, 14 % and 27 %, and plant nitrogen accumulation increased by 17 %. Compared with conventional molybdenum fertilizer, MoO3NPs had a greater effect on apigenin, kaempferol and other flavonoid, and the expression of nodulation related genes such as ENOD93, F3'H. Based on WGCNA analysis, we identified a core gene GmCHS9 that was positively responsive to molybdenum and was highly expressed during MoO3NPs induced nodulation. MoO3NPs could improve the nitrogen fixation ability of soybean by promoting the secretion of flavonoids and the expression of key genes. This study provided a new perspective for the nano-strengthening strategy of nodules development and flavonoid biosynthesis by molybdenum.

Overexpression of GmPAP4 Enhances Symbiotic Nitrogen Fixation and Seed Yield in Soybean under Phosphorus-Deficient Condition.

Legume crops establish symbiosis with nitrogen-fixing rhizobia for biological nitrogen fixation (BNF), a process that provides a prominent natural nitrogen source in agroecosystems; and efficient nodulation and nitrogen fixation processes require a large amount of phosphorus (P). Here, a role of GmPAP4, a nodule-localized purple acid phosphatase, in BNF and seed yield was functionally characterized in whole transgenic soybean (Glycine max) plants under a P-limited condition. GmPAP4 was specifically expressed in the infection zones of soybean nodules and its expression was greatly induced in low P stress. Altered expression of GmPAP4 significantly affected soybean nodulation, BNF, and yield under the P-deficient condition. Nodule number, nodule fresh weight, nodule nitrogenase, APase activities, and nodule total P content were significantly increased in GmPAP4 overexpression (OE) lines. Structural characteristics revealed by toluidine blue staining showed that overexpression of GmPAP4 resulted in a larger infection area than wild-type (WT) control. Moreover, the plant biomass and N and P content of shoot and root in GmPAP4 OE lines were also greatly improved, resulting in increased soybean yield in the P-deficient condition. Taken together, our results demonstrated that GmPAP4, a purple acid phosphatase, increased P utilization efficiency in nodules under a P-deficient condition and, subsequently, enhanced symbiotic BNF and seed yield of soybean.

Unclenching the potentials of global core germplasm for root nodulation traits for increased biological nitrogen fixation and productivity in chickpea (Cicer arietinum L.)

Chickpea being an important food legume crop is able to fix the atmospheric nitrogen and form root nodules that support biologicalnitrogen fixation- a sustainable alternative for nitrogen supply to agriculture worldwide. In order to support findings on nodule formation in chickpeas, a diverse core set of 300 chickpea genotypes, including four checks, was evaluated for morphological and nodulation traits in four different environments. The maximum genotypic and phenotypic coefficient of variation was observed for a number of nodules, nodule fresh weight, shoot fresh weight, and number of seeds per plant. The heritability for most of the characters ranged from 26.56 for days to 50% flowering to 99.61 for a number of pods per plant. The genotypic and phenotypic correlation coefficient analysis revealed that the number of nodules was positively correlated with seed yield. Further, seed yield was partitioned into direct and indirect effects at genotypic and phenotypic levels through path coefficient analysis. Significant genotypic correlations and direct positive effects were exhibited by a number of nodules and number of pods per plant on grain yield. Based on the D2 statistics, the number of seeds per plant, number of pods per plant, shoot fresh weight and number of nodules have been identified as top-ranking yield contributing traits. The genotypes ICC1013 and ICC16569 for a number of nodules and ICC1049 for the trait number of seeds per plant were identified as potential stable donors for the respective traits with high mean yield, heritability and genetic advance across the locations and can be used as donors in the chickpea breeding programs for increasing biological nitrogen fixation and enhancement of the crop productivity.

Effect of Microbial Consortia Inoculation and Chemical Fertilizers on Growth Parameter and Nodulation of Soybean (Glycine max L. merill.) and Chickpea (Cicer arietinum L.)

Microbial consortia inoculation and chemical fertilizers significantly impact plant growth parameters. Microbial consortia contribute to soil health by enhancing nutrient availability and promoting plant growth, while chemical fertilizers provide essential nutrients. In this study, an Field Experiment was conducted during two successive years in Kharif and Rabi 2020-21 and 2021-22 consecutively on effect of microbial consortia inoculation and chemical fertilizers on productivity and soil properties in soybean chickpea sequence on vertisol at research farm of department soil science and agricultural chemistry Vasantrao Naik Marathwada Agricultural University, Parbhani (MAH) India. The Soil of experimental site was classified as vertisol (Typic Haplustert) dominant montmorillonite type with kaollinite and illite mineral alkaline in reaction. Experimental treatments consist of four levels of laboratory evaluated microbial cultures (Bradyrhizobium, Mesorhizobium, Bacillus megaterium, Pseudomonas striata, Thiobacillus thioxidant) and uninoculated control and four levels of chemical fertilizers (100 % RDF, 75 % RDF, 50 % RDF and Control i.e. (without fertilizers)). Seed treatment of soybean and chickpea was done with microbial consortia immediate before sowing and chemical fertilizers were applied at the time of sowing as per treatments. The results revealed that the application of microbial inoculants with chemical fertilizers showed significant effect on biometric attributes and nodulation of soybean and chickpea. The microbial consortia Rhizobium spp.+ Pseudomonas striata inoculation has highest plant height, shoot weight, root length, number of nodule, fresh weight of nodules, and dry weight of noduels in both crops as compared to uninoculated control. However, the application of chemical fertilizer i.e. N,P and K 100% RDF obviously increased the height, shoot weight, number of nodulation, and fresh weight of nodules in respect of both soybean and chickpea crops. The chemical fetilizers N,P and K are applied in the form of Urea, single super phosphate and muriate of potash respectively.

Legume nodulation and nitrogen fixation require interaction of DnaJ-like protein and lipid transfer protein.

The lipid transport protein (LTP) product of the AsE246 gene of Chinese milk vetch (Astragalus sinicus) contributes to the transport of plant-synthesized lipids to the symbiosome membranes (SMs) that are required for nodule organogenesis in this legume. However, the mechanisms used by nodule-specific LTPs remain unknown. In this study, a functional protein in the DnaJ-like family, designated AsDJL1, was identified and shown to interact with AsE246. Immunofluorescence showed that AsDJL1 was expressed in infection threads (ITs) and in nodule cells and that it co-localized with rhizobium, and an immunoelectron microscopy assay localized the protein to SMs. Via co-transformation into Nicotiana benthamiana cells, AsDJL1 and AsE246 displayed subcellular co-localization in the cells of this heterologous host. Co-immunoprecipitation assays confirmed that AsDJL1 interacted with AsE246 in nodules. The essential interacting region of AsDJL1 was determined to be the zinc finger domain at its C-terminus. Chinese milk vetch plants transfected with AsDJL1-RNAi had significantly decreased numbers of ITs, nodule primordia and nodules as well as reduced (by 83%) nodule nitrogenase activity compared with the controls. By contrast, AsDJL1 overexpression led to increased nodule fresh weight and nitrogenase activity. RNAi-AsDJL1 also significantly affected the abundance of lipids, especially digalactosyldiacylglycerol, in early-infected roots and transgenic nodules. Taken together, the results of this study provide insights into the symbiotic functions of AsDJL1, which may participate in lipid transport to SMs and play an essential role in rhizobial infection and nodule organogenesis.

Root Growth, Nutrient Uptake, Nodulation and Yield of Summer Mung [Vigna radiata (L.) Wilczek] as Influenced by Land Configuration and Varying Nutrient Management Practices under Coastal Plains of Odisha

Background: Green gram being an important legume crop, its rooting traits and nodule characteristics are vital in determining its overall productivity. Land configuration plays a crucial role in influencing the root and nodule growth in green gram. Judicious use of balanced nutrients and fertilizers is needed owing to the sustainability concern of the environment and also for optimising the production process. Methods: Field experiments were carried out at the Agronomy Main Research Farm, O.U.A.T. Bhubaneswar, Odisha, India during 2020 and 2021 to study the effect of different land configuration methods and varying nutrient management practices on the root growth, nutrient uptake and yield of summer mung. Split-plot Design was adopted with three replications having four main plot and 6 sub-plot treatments. Result: The outcomes of the experiment showed that raised bed method with PDM-139 cultivar gave the highest pooled root length (13.1 cm), root dry weight (1.52 g) and shoot: root ratio (6.83). F6 nutrient management treatment gave synonymous results (12.16 cm root length, 1.53 g root dry weight). Similar trend was observed for number of nodules (15.48 nodules/plant) and nodule fresh weight (25.50 g) under land configuration, variety and (16.61 nodules/plant, 25.50 g) under nutrient management respectively. The total nutrient uptake in grain and straw for nitrogen, phosphorous and potassium was found to be the highest in flat-bed method with PDM-139 cultivar. The result revealed that sowing of green gram on raised bed land configuration with PDM 139 along with nutrient management practice based on STCR equations (F6) significantly produced more yield (522.84 kg/ha and 455.29 kg/ha respectively) than the other treatments. The study revealed that there was positive correlation between the grain yield and the respective N, P2O5 and K2O uptakes.

“Alperujo” Compost Improves Nodulation and Symbiotic Nitrogen Fixation of Soybean Inoculated with Bradyrhizobium diazoefficiens

The utilization of compost to enhance plant productivity and symbiotic nitrogen fixation (SNF) has been recognized as an effective alternative to synthetic nitrogen fertilizers. This environmentally sustainable method is readily accessible to farmers. This study investigated the effect of olive pomace (“alperujo”, AL) compost on the nodulation and SNF of soybeans (Glycine max L.) and their natural symbiont (Bradyrhizobium diazoefficiens). For that, soybean plants were subjected to several doses of AL compost under controlled greenhouse conditions. At the end of the experiment, the dry weight of plant biomass (aerial part and roots), the number and fresh weight of nodules, and nitrogen and leghaemoglobin contents were analyzed. The application of AL compost significantly improved soybean growth, as demonstrated by an increase in both plant biomass and height. Furthermore, nodular leghaemoglobin content and nitrogen content were found to be enhanced by the addition of AL compost (7 and 40%, respectively), indicating an increase in nodule effectiveness and symbiotic efficiency. Our results provide clear evidence of the synergetic effect of AL compost on the soybean-B. diazoefficiens association, probably due to AL-compost improved soybean roots development, and rhizospheric organic matter and nutrients assimilation by rhizobia.

Non-rhizobial nodule endophytes improve nodulation, change root exudation pattern and promote the growth of lentil, for prospective application in fallow soil.

Non-rhizobial endophytes (NREs) are active colonizers inhabiting the root nodules. Though their active role in the lentil agroecosystem is not well defined, here we observed that these NREs might promote the growth of lentils, modulate rhizospheric community structure and could be used as promising organisms for optimal use of rice fallow soil. NREs from root nodules of lentils were isolated and examined for plant growth-promoting traits, exopolysaccharide (EPS) and biofilm production, root metabolites, and the presence of nifH and nifK elements. The greenhouse experiment with the chosen NREs, i.e., Serratia plymuthica 33GS and Serratia sp. R6 significantly increased the germination rate, vigour index, development of nodules (in non-sterile soil) and fresh weight of nodules (33GS 94%, R6 61% growth) and length of the shoot (33GS 86%, R6 51.16%) as well as chlorophyll levels when compared to the uninoculated control. Scanning Electron Microscopy (SEM) revealed that both isolates could successfully colonize the roots and elicit root hair growth. The inoculation of the NREs resulted in specific changes in root exudation patterns. The plants with 33GS and R6 treatment significantly stimulated the exudation of triterpenes, fatty acids, and their methyl esters in comparison to the uninoculated plants, altering the rhizospheric microbial community structure. Proteobacteria dominated the rhizospheric microbiota in all the treatments. Treatment with 33GS or R6 also enhanced the relative abundance of other favourable microbes, including Rhizobium, Mesorhizobium, and Bradyrhizobium. The correlation network analysis of relative abundances resulted in numerous bacterial taxa, which were in cooperation with each other, having a possible role in plant growth promotion. The results indicate the significant role of NREs as plant growth promoters, which also includes their role in root exudation patterns, enhancement of soil nutrient status and modulation of rhizospheric microbiota, suggesting their prospects in sustainable, and bio-based agriculture.

Conjunctive Use of Fe, Zn and Bio-Fertilizers on Growth, Nodulation and Chlorophyll Content of Urdbean (Vigna mungo L.)

An experiment was conducted on urdbean during kharif 2021 at Instructional Farm, College of Agriculture, Ummedganj, Kota (Rajasthan). The experiment comprised of 10 treatments viz. (Control, 75% RDF, 100% RDF, 75% RDF + Rhizobium @ 600 g ha-1 seed inoculation, 75% RDF + PSB @ 600 g ha-1 seed inoculation, 75% RDF + Rhizobium @ 600 g ha-1 + PSB @ 600 g ha-1, 75% RDF + 0.1% FeSO4 + 0.5% ZnSO4 at pre flowering and pod formation stage, 75% RDF + 0.1% FeSO4 + 0.5% ZnSO4 at pre flowering and pod formation stage + Rhizobium @ 600 g ha-1, 75% RDF + 0.1% FeSO4 + 0.5% ZnSO4 at pre flowering and pod formation stage + PSB @ 600 g ha-1, 75% RDF + 0.1% FeSO4 + 0.5% ZnSO4 at pre flowering and pod formation stage + Rhizobium 600 g ha-1+ PSB @ 600 g ha-1) was carried out in randomized block design with three replications. Significantly higher plant height at 60 DAS (25.28 cm) and at harvest (34.43 cm), nodules plant-1 (29.22) at 45 DAS, nodule fresh weight (86.31 mg plant-1) at 45 DAS, chlorophyll content (3.19 mg g-1) at 45 DAS and dry matter accumulation (2.71, 5.94 and 9.99 g plant-1) at 30, 60 DAS and at harvest were recorded with application of 75% RDF + 0.1% FeSO4 + 0.5% ZnSO4 at pre flowering and pod formation stage + Rhizobium 600 g ha-1+ PSB @ 600 g ha-1 in urdbean over rest of the treatments. Among these treatments, application of 75% RDF + 0.1% FeSO4 + 0.5% ZnSO4 at pre flowering and pod formation stage + Rhizobium 600 g ha-1+ PSB @ 600 g ha-1 produced maximum seed yield (1269.30 kg ha-1) of urdbean.

Characterization of phosphate solubilizing Pseudomonas stutzeri for nodulation in chickpea

Phosphorus is a vital but least mobile element in plants and soil as compared to other macronutrients. Native phosphate solubilizing bacterial strains were isolated from the rhizosphere of chickpea. Based on in vitro study, the isolate showed lower pH, remarkable phosphate solubilizing index, and thermotolerant ability selected for further characterization. The 16 s rRNA sequencing confirmed that the isolate showed 99.23% similarity with Pseudomonas stutzeri CW202. Pot trial treatments include Rhizobium ciceri, Pseudomonas stutzeri, and fertilizer alone and in combination with inoculants and control. The results of co-inoculation with R. ciceri + P. stutzeri showed the highest germination rate, increase in nodule number, and fresh nodule weight. This treatment was at par in plant height, number of branches, shoot and root dry weight per plant, number of pods per plant, seeds per pod, 100 seed weight and phosphorus uptake in seed and straw over the best treatment R. ciceri + P. stutzeri + Fertilizer. Co-inoculation of R. ciceri + P. stutzeri shows not only significant enhancement in nodulation, nodule fresh weight but also yield attributes and phosphorous uptake as compared to R. ciceri alone, indicating its role in phosphorus nutrition in chickpea. The results infer that the native P. stutzeri could be considered as a proficient biofertilizer in the organic farming system.

Nodulation and Growth Promotion of Chickpea by Mesorhizobium Isolates from Diverse Sources.

The cultivation of chickpea (Cicer arietinum L.) in South Africa is dependent on the application of suitable Mesorhizobium inoculants. Therefore, we evaluated the symbiotic effectiveness of several Mesorhizobium strains with different chickpea genotypes under controlled conditions. The tested parameters included shoot dry weight (SDW), nodule fresh weight (NFW), plant height, relative symbiotic effectiveness (RSE) on the plant as well as indole acetic acid (IAA) production and phosphate solubilization on the rhizobia. Twenty-one Mesorhizobium strains and six desi chickpea genotypes were laid out in a completely randomized design (CRD) with three replicates in a glasshouse pot experiment. The factors, chickpea genotype and Mesorhizobium strain, had significant effects on the measured parameters (p < 0.001) but lacked significant interactions based on the analysis of variance (ANOVA). The light variety desi genotype outperformed the other chickpea genotypes on all tested parameters. In general, inoculation with strains LMG15046, CC1192, XAP4, XAP10, and LMG14989 performed best for all the tested parameters. All the strains were able to produce IAA and solubilize phosphate except the South African field isolates, which could not solubilize phosphate. Taken together, inoculation with compatible Mesorhizobium promoted chickpea growth. This is the first study to report on chickpea-compatible Mesorhizobium strains isolated from uninoculated South African soils with no history of chickpea production; although, their plant growth promotion ability was poorer compared to some of the globally sourced strains. Since this study was conducted under controlled conditions, we recommend field studies to assess the performance of the five highlighted strains under environmental conditions in South Africa.

Biological N fixation but not mineral N fertilization enhances the accumulation of N in peanut soil in maize/peanut intercropping system

Legume/cereal intercropping has the potential to maximize the use of resources to raise yields due to enhanced nitrogen (N) fixation by legume root nodules, while high N fertilization may inhibit the nodulation of legume. However, whether legume/cereal intercropping can promote the accumulation of soil N storage with N fertilization and its underlying mechanism are less clear. Here, we evaluated the long-term (5 years) effects of maize/peanut intercropping and mineral N fertilization on peanut soil total N content and soil N cycling functional genes. The experiment includes two planting patterns (peanut maize intercropping and peanut monocropping) with three N fertilization rates (0, 150, and 300 kg N ha −1 ). Intercropping increased soil total N content (STN) by average 18.2%, and the positive effect of intercropping on STN decreased with N application rate. Highest N application decreased the nodule fresh weight (NFW) by 64.3% and 46.0% in intercropping and monocropping system, respectively. However, intercropping has no effect on NFW. Intercropping increased the nif H gene abundance by average 26.5%. SEM analysis indicated that NFW and nif H gene abundance combined can explain 46% of the variance of STN. Our results indicate that biological N fixation but not mineral N fertilization enhances the accumulation of N in soil planted with peanut in maize/peanut intercropping system. • Maize/peanut Intercropping increased the abundance of nif H gene in peanut soil. • Nitrogen (N) fertilization decreased the nodule fresh weight (NFW) of peanut root. • nif H and NFW can explain 46% of the variance of soil total N.

Improved Nitrogen Utilization of Faba Bean (Vicia faba L.) Roots and Plant Physiological Characteristics under the Combined Application of Organic and Inorganic Fertilizers

As one of the most important edible legumes worldwide, faba bean can be grown for grain, feed, vegetable, fertilizer, medicine and deep processing. In this study, experiments were designed to determine the combined effect of organic and inorganic fertilizers on the growth and development of faba bean. Dabaipi (a cultivar of Vicia faba L.) was used for the experiments. Five treatments with different ratios of organic nitrogen (N) to total N were applied, including 0% organic fertilizer (0% OF), 25% OF, 50% OF, 75% OF, 100% OF and 0% OF. Chemical urea was used as an inorganic fertilizer. The experimental results showed that 50% OF resulted in the highest faba bean yield, up to 10,337.39 and 13,595.7 kg ha−1 in 2018 and 2019, respectively. Compared with 0% OF, 50% OF increased the yield by 84.47% and 183.17%, respectively. The regression analysis showed that the yield could be maximized when ROT accounted for 51.1%. The 50% OF treatment significantly increased N accumulation in seeds, resulting in higher N partial factor productivity and N harvest index (NHI). N accumulation in green seeds and aboveground plant parts had a significantly positive linear correlation with the yield and NHI, respectively. The 50% OF treatment maintained appropriate N accumulation in vegetative organs and higher N accumulation in reproductive organs and whole plants. Compared to 0% OF, the 50% OF treatment increased the total nodule number per plant (52.5%), fresh nodule weight (55.8%), nitrate reductase activity (70.7%), glutamine synthetase (18.2%) and glutamate synthase activity (42.4%). Therefore, the combined application of 50% OF and 50% inorganic fertilizer can be recommended for faba bean cultivation. This study will provide a theoretical basis for high-yield cultivation of faba bean.

GmTOC1b inhibits nodulation by repressing GmNIN2a and GmENOD40-1 in soybean.

Symbiotic nitrogen fixation is an important factor affecting the yield and quality of leguminous crops. Nodulation is regulated by a complex network comprising several transcription factors. Here, we functionally characterized the role of a TOC1 family member, GmTOC1b, in soybean (Glycine max) nodulation. RT-qPCR assays showed that GmTOC1b is constitutively expressed in soybean. However, GmTOC1b was also highly expressed in nodules, and GmTOC1 localized to the cell nucleus, based on transient transformation in Nicotiana benthamiana leaves. Homozygous Gmtoc1b mutant plants exhibited increased root hair curling and produced more infection threads, resulting in more nodules and greater nodule fresh weight. By contrast, GmTOC1b overexpression inhibited nodulation. Furthermore, we also showed that GmTOC1b represses the expression of nodulation-related genes including GmNIN2a and GmENOD40-1 by binding to their promoters. We conclude that GmTOC1b functions as a transcriptional repressor to inhibit nodulation by repressing the expression of key nodulation-related genes including GmNIN2a, GmNIN2b, and GmENOD40-1 in soybean.

Treatment with atypical rhizobia, Pararhizobium giardinii and Ochrobactrum sp. modulate the rhizospheric bacterial community, and enhances Lens culinaris growth in fallow-soil

Diazotrophic nodule isolates are acknowledged promoters of plant growth and rhizospheric community. Consequently, in the lentil agroecosystem, inoculation of atypical rhizobial isolates could be a viable alternative to chemical fertilizers for fallow land usage optimization. The aim of this study is to evaluate and select the rhizobial isolates of lentil nodules with plant-growth-promoting (PGP) attributes and to elucidate their application in rice-fallow soil for determining the growth of lentils and its impact on the rhizospheric bacterial community. Lentil’s nodule isolates were identified and screened for their PGP attributes, biofilm, exopolysaccharide (EPS) formation, and early plant growth promotion. The pot experiment with the selected atypical rhizobial isolates Pararhizobium giardinii (P1) and Ochrobactrum sp. (42S) significantly enhanced germination, vigour index, nodule formation (P1 60%, 42S 42% increase), nodule fresh weight, shoot length (65% P1 & 35% 42S), and chlorophyll content as compared to the uninoculated control treatment. The genes for nitrogen fixation nifH and nifK were detected in both isolates. Scanning Electron Microscopy (SEM) revealed successful root and nodule colonization by both isolates, while Transmission Electron Microscopy (TEM) displayed nitrogen-fixing zones within root nodules. Proteobacteria predominated in the lentil rhizosphere of all the treatments. Whereas, application of either P1 or 42S increased Rhizobium, Mesorhizobium, and Bradyrhizobium genra, thus positively modulating rhizospheric community structure. The correlation network analysis revealed an abundance of some interdependent bacterial genera with a possible role in overall plant growth. Functional genes for siderophore biosynthesis and ABC transporter were positively modulated by application of either P1 or 42S. This study showed the significant effect of P. giardinii P1 and Ochrobactrum sp. 42S of L. culinaris on lentil growth, improving fallowsoil health for optimum usage, and modulated rhizospheric community structure which strongly manifest prospects of low-cost, eco-friendly and sustainable biofertilizers.