Search Results (7)

Nitrogen fixation in legume nodules is crucial for plant growth and development. Therefore, this study aims to investigate the effects of nitric oxide [S-nitrosoglutathione (GSNO)] and silicon [sodium metasilicate (Si)], both individually and in combination, on soybean growth, nodule formation, leghaemoglobin (Lb) synthesis, and potential post-translational modifications. At the V1 stage, soybean plants were treated for 2 weeks with 150 µM GSNO, and Si at concentrations of 1 mM, 2 mM, and 4 mM. The results showed that NO and Si enhance the nodulation process by increasing phenylalanine ammonia-lyase activity and Nod factors (NIP2-1), attracting rhizobia and accelerating nodule formation. This leads to a greater number and larger diameter of nodules. Individually, NO and Si support the synthesis of Lb and leghaemoglobin protein (Lba) expression, ferric leghaemoglobin reductases (FLbRs), and S-nitrosoglutathione reductase (GSNOR). However, when used in combination, NO and Si inhibit these processes, leading to elevated levels of S-nitrosothiols in the roots and nodules. This combined inhibition may potentially induce post-translational modifications in FLbRs, pivotal for the reduction of Lb³⁺ to Lb²⁺. These findings underscore the critical role of NO and Si in the nodulation process and provide insight into their combined effects on this essential plant function. Full article

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. Full article

Root system architecture plays a vital role in plant growth, development, and adaptation by absorbing water and nutrients and providing mechanical support for growing plants. Unfortunately, little information is available in the literature on the root dynamics of summer mung bean under conservation agriculture conditions. In this study, field experiments were conducted during the summer seasons of two consecutive years (2020 and 2021) to investigate the root system dynamics of summer mung bean under different conservation agriculture practices. The highest stem and system width, depth to width length, number of nodal roots, taproot diameter, secondary root length (both right and left) of summer mung bean were recorded in the Soybean (permanent bed; PB)-Wheat(PB)-Summer mung (PB)(+Residual; +R) based cropping systems, followed by Maize(PB)-Wheat(PB)-Summer mung (PB)(+R), while, the lowest values of above parameters were recorded in the Puddled Transplanted Rice–Conventional till (PTR-CT)Wheat-Summer mung (-R). Further, the pod length, number of seeds per pod, number of pods per plant, seed yield and symbiotic parameters (including number of nodules per plant, leghaemoglobin content) and root dry weight were recorded highest in Soybean (PB)-Wheat (PB)-Summer mung (PB)(+R). Interestingly, the yield of summer mung bean increased around 13.4–29.5% when residues were retained on the soil surface with treatments involving residual removal. The soil dehydrogenase enzyme activity increased significantly under Soybean (PB)-Wheat (PB)-Summer mung (PB)(+R) based cropping system as compared to PTR-CT Wheat-Summer mung (-R). In addition, the number of pods per plant exhibited a significantly positive correlation with yield during both crop seasons. Overall, this study suggests that the inclusion of summer mung in soybean-based cropping systems may substantially improve the root architecture and soil quality and increase crop yield under conservation agriculture. Full article

The key plant nutrients determine the crop’s nutritional status and vigor, while their deficiency impairs the plant growth resulting in absolute failure of crop productivity. Phosphorus is the second major essential nutrient for the growth and establishment of crops. Drastic variations in climatic conditions across the world and low soil fertility, especially phosphorous (P) fixation in alkaline calcareous soils of arid climate have become serious issues threatening the productivity of crops. In this regard, the application of different organic fertilizers in combination with the lower dose of chemical fertilizers has been proved as an effective strategy to improve plant growth and yield. Thus, a pot experiment was conducted in order to evaluate the combined effects of animal manures (normal and processed) along with the recommended and half of the chemical fertilizer di-ammonium phosphate (DAP) on the growth, physiology, nodulation, and yield of chickpea. Results show that the animal manure (normal and processed) with half or recommended dose of DAP significantly improved the growth, yield, and physiological attributes of the chickpea. However, the combined application of normal animal manure with half DAP showed the highest results among all other treatments. It increased the contents of leghaemoglobin, P, K, primary branches, pods, and seed weight up to 113.7%, 97.8%, 80.6%, 78.5%, 119%, and 145% over control, respectively. This treatment also increased protein contents, nodule count, and nodule weight up to 78.38%, 147%, and 93.59% than the control, respectively. Maximum chlorophyll b contents (0.78 μg/mL) were obtained with the application of a recommended dose of DAP alone. These indigenous manure applications provide a novel value addition that is critical to boosting crop yield and agricultural sustainability. Full article

Multimodal spectroscopic imaging methods such as Matrix Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI MSI), Fourier Transform Infrared spectroscopy (FT-IR) and Raman spectroscopy were used to monitor the changes in distribution and to determine semi quantitatively selected metabolites involved in nitrogen fixation in pea root nodules. These approaches were used to evaluate the effectiveness of nitrogen fixation by pea plants treated with biofertilizer preparations containing Nod factors. To assess the effectiveness of biofertilizer, the fresh and dry masses of plants were determined. The biofertilizer was shown to be effective in enhancing the growth of the pea plants. In case of metabolic changes, the biofertilizer caused a change in the apparent distribution of the leghaemoglobin from the edges of the nodule to its centre (the active zone of nodule). Moreover, the enhanced nitrogen fixation and presumably the accelerated maturation form of the nodules were observed with the use of a biofertilizer. Full article

Drought or water stress is a limiting factor that hampers the growth and yield of edible crops. Drought-tolerant plant growth-promoting rhizobacteria (PGPR) can mitigate water stress in crops by synthesizing multiple bioactive molecules. Here, strain PAB19 recovered from rhizospheric soil was biochemically and molecularly characterized, and identified as Enterobacter sp./Leclercia adecarboxylata (MT672579.1). Strain PAB19 tolerated an exceptionally high level of drought (18% PEG-6000) and produced indole-3-acetic acid (176.2 ± 5.6 µg mL⁻¹), ACC deaminase (56.6 ± 5.0 µg mL⁻¹), salicylic acid (42.5 ± 3.0 µg mL⁻¹), 2,3-dihydroxy benzoic acid (DHBA) (44.3 ± 2.3 µg mL⁻¹), exopolysaccharide (204 ± 14.7 µg mL⁻¹), alginate (82.3 ± 6.5 µg mL⁻¹), and solubilized tricalcium phosphate (98.3 ± 3.5 µg mL⁻¹), in the presence of 15% polyethylene glycol. Furthermore, strain PAB19 alleviated water stress and significantly (p ≤ 0.05) improved the overall growth and biochemical attributes of Vigna radiata (L.) R. Wilczek. For instance, at 2% PEG stress, PAB19 inoculation maximally increased germination, root dry biomass, leaf carotenoid content, nodule biomass, leghaemoglobin (LHb) content, leaf water potential (ΨL), membrane stability index (MSI), and pod yield by 10%, 7%, 14%, 38%, 9%, 17%, 11%, and 11%, respectively, over un-inoculated plants. Additionally, PAB19 inoculation reduced two stressor metabolites, proline and malondialdehyde, and antioxidant enzymes (POD, SOD, CAT, and GR) levels in V. radiata foliage in water stress conditions. Following inoculation of strain PAB19 with 15% PEG in soil, stomatal conductance, intercellular CO₂ concentration, transpiration rate, water vapor deficit, intrinsic water use efficiency, and photosynthetic rate were significantly improved by 12%, 8%, 42%, 10%, 9% and 16%, respectively. Rhizospheric CFU counts of PAB19 were 2.33 and 2.11 log CFU g⁻¹ after treatment with 15% PEG solution and 8.46 and 6.67 log CFU g⁻¹ for untreated controls at 40 and 80 DAS, respectively. Conclusively, this study suggests the potential of Enterobacter sp./L. adecarboxylata PAB19 to alleviate water stress by improving the biological and biochemical features and of V. radiata under water-deficit conditions. Full article

Soybean (Glycine max.) is one of the most important legumes cultivated worldwide. Its productivity can be altered by some biotic and abiotic stresses like global warming, soil metal pollution or over-application of herbicides like paraquat (1,1’-dimethyl-4,4’-bipyridinium dichloride). In this study, the effect of oxidative stress produced by paraquat addition (0, 20, 50 and 100 µM) during plant growth on symbiotic nitrogen fixation (SNF) and functionality of Bradyrhizobium diazoefficiens-elicited soybean nodules were evaluated. Results showed that the 50 µM was the threshold that B. diazoefficiens can tolerate under free-living conditions. In symbiosis with soybean, the paraquat addition statistically reduced the shoot and root dry weight of soybean plants, and number and development of the nodules. SNF was negatively affected by paraquat, which reduced total nitrogen content and fixed nitrogen close to 50% when 100 µM was added. These effects were due to the impairment of nodule functionality and the increased oxidative status of the nodules, as revealed by the lower leghaemoglobin content and the higher lipid peroxidation in soybean nodules from paraquat-treated plants. Full article