Soybean Seedlings Research Articles

The Effect of Sowing Date on the Growth and Yield of Soybeans Cultivated in North-Eastern Poland

Soybean yields are influenced by numerous factors, including environmental conditions, location, and agricultural practices. Sowing date affects plant growth, development, and yields, and it plays a particularly important role in soybean cultivation. The optimal sowing date should be selected based on soil temperature, precipitation, and rainfall distribution in a given region. The aim of this study was to determine the effect of various sowing dates (I—early, II—optimal, III—late) on the time from sowing to emergence of soybean seedlings, length of the growing season, morphological traits of soybean plants, yield components, and seed yields of soybeans grown in north-eastern Poland. Sowing date considerably affected the time from sowing to the emergence of soybean seedlings and seed yields. In north-eastern Poland, soybeans should be sown in the first half of May to minimize the risk of ground frost damage, which can occur even in late May. Sowing date also influenced soybean yields. In north-eastern Poland (Region of Warmia and Mazury), yields were maximized when soybeans were sown late (in mid-May), which was decisively influenced by climatic conditions, mainly temperature. The linear regression analysis revealed that the length of the growing season was correlated with the seed yields of soybeans sown on different dates.

Cloning of the Soybean GmNHL1 Gene and Functional Analysis under Salt Stress.

When encountered in the soybean seedling stage, salt stress has serious impacts on plant growth and development. This study explores the role of the soybean NDR1/HIN1-like family gene GmNHL1 under salt stress. First, the GmNHL1 gene was successfully cloned, and bioinformatic analysis revealed multiple cis-acting elements which are related to adversity stress and involved in the oxidative response in the promoter region. Sub-cellular localization analysis indicated that the protein expressed by GmNHL1 was localized on the cell membrane. An over-expression vector of the target gene and a CRISPR/Cas9 gene-editing vector were constructed, and the recipient soybean variety Jinong 74 was genetically transformed using the Agrobacterium tumefaciens-mediated method. By analyzing the performance of the different plants under salt stress, the results showed that GmNHL1 was over-expressed in the T2 generation. The germination potential, germination rate, germination index, and vitality index of the strain were significantly higher than those of the recipient control JN74. Under salt stress conditions, the root microanatomical structure of the GmNHL1 over-expressing material remained relatively intact, and its growth was better than that of the recipient control JN74. Measurement of physiological and biochemical indicators demonstrated that, compared with the receptor control JN74, the malondialdehyde and O2- contents of the GmNHL1 over-expressing material were significantly reduced, while the antioxidant enzyme activity, proline content, and chlorophyll content significantly increased; however, the results for GmNHL1 gene-edited materials were the opposite. In summary, over-expression of GmNHL1 can improve the salt tolerance of plants and maintain the integrity of the root anatomical structure, thereby more effectively and rapidly reducing the accumulation of malondialdehyde and O2- content and increasing antioxidant enzyme activity. This reduces cell membrane damage, thereby improving the salt tolerance of soybean plants. These results help to better understand the mechanism of salt tolerance in soybean plants, laying a theoretical foundation for breeding new stress-resistant varieties of soybean.

Remediation of atrazine in environment by persulfate activation via N/B co-doped Si-rich biochar: Performance, mechanisms, degradation pathways and phytotoxicity

Biochar activated with peroxydisulfate (PDS) has been widely applied in the removal of recalcitrant organic pollutants in the environment, but its wide application is limited by expensive and complex preparation process. In this study, a nitrogen and boron-doped silicon-rich biochar (NBC) was prepared by one-pot synthesis using fungus chaff of Auricularia auricula, diatomite, urea and boric acid as raw materials. The results showed that the specific surface area of NBC was 9 times that of the original, the adsorption capacity of ATZ was increased by 8 times, PDS could be effectively activated, and the removal efficiency of ATZ was as high as 98%. Density functional theory analysis proved that NBC had a lower energy barrier and a higher probability of activating PDS, thereby degrading ATZ through a non-radical pathway dominated by electron transfer. Hydroponic and pot experiments showed that NBC/PDS system effectively restored the growth status, leaf and root morphology, and chlorophyll content of plants, demonstrating the ability to efficiently remediate the toxicity of ATZ on soybean seedlings. This study not only proposed a novel biochar material as an efficient PDS activator but also provided new insights into the practical application of heteroatom-doped carbon catalysts for activating advanced oxidation processes in pollutant degradation.

Tetracycline inhibits the nitrogen fixation ability of soybean (Glycine max (L.) Merr.) nodules in black soil by altering the root and rhizosphere bacterial communities

Tetracycline is a widely used antibiotic and may thus also be an environmental contaminant with an influence on plant growth. The aim of this study was to investigate the inhibition mechanisms of tetracycline in relation to soybean growth and ecological networks in the roots and rhizosphere. To this end, we conducted a pot experiment in which soybean seedlings were grown in soil treated with 0, 10, or 25 mg/kg tetracycline. The effects of tetracycline pollution on growth, productivity, oxidative stress, and nitrogenase activity were evaluated. We further identified the changes in microbial taxa composition and structure at the genus and species levels by sequencing the 16S rRNA gene region. The results showed that tetracycline activates the antioxidant defense system in soybeans, which reduces the abundance of Bradyrhizobiaceae, inhibits the nitrogen-fixing ability, and decreases the nitrogen content in the root system. Tetracycline was also found to suppress the formation of the rhizospheric environment and decrease the complexity and stability of bacterial networks. Beta diversity analysis showed that the community structure of the root was markedly changed by the addition of tetracycline, which predominantly affected stochastic processes. These findings demonstrate that the influence of tetracycline on soybean roots could be attributed to the decreased stability of the bacterial community structure, which limits the number of rhizobium nodules and inhibits the nitrogen-fixing capacity. This exploration of the inhibitory mechanisms of tetracycline in relation to soybean root development emphasises the potential risks of tetracycline pollution to plant growth in an agricultural setting. Furthermore, this study provides a theoretical foundation from which to improve our understanding of the physiological toxicity of antibiotics in farmland.

Antifungal activity of Klebsiella grimontii DR11 against Fusarium oxysporum causing soybean root rot.

Soybean root rot, caused by Fusarium oxysporum, leads to significant economic and financial losses to the soybean processing industry globally. In the study, we aimed to explore a biocontrol agent to combat F. oxysporum infection in soybean. From soybean rhizosphere soil, 48 strains were isolated. Among them, the strain DR11 exhibited the highest inhibition rate of 72.27%. Morphological, physiological, biochemical, and 16S rDNA identification revealed that the strain DR11 was Klebsiella grimontii DR11. Strain DR11 could inhibit the growth of F. oxysporum and spore formation and alter the mycelial morphology. At 5.0 × 106 CFU mL-1, pH 7, and 30 °C, it exhibited the highest inhibitory rate (72.27%). Moreover, it could decrease the activity of cell-wall-degrading enzymes of F. oxysporum. Simultaneously, the activities of defense-related enzymes and content of malondialdehyde in soybean plants were increased after treatment with strain DR11. In addition, strain DR11 could form aggregates to form biofilm and adsorb on the surface of soybean roots. It inhibited F. oxysporum growth on soybean seedlings, with an inhibitory effect of 62.71%. K. grimontii DR11 had a strong inhibitory effect on F. oxysporum and could be used as a biocontrol agent to combat F. oxysporum infection in soybean.

Regular Mechanical Stimuli Enhanced Tolerance to Salinity Stress in Glycine max L. Seedlings

Regular touch treatment leads to plant adaptations that enhances mechanical strength. In many crop plants these adaptations result in cross-tolerance to biotic stress caused by bacterial or fungal infection and abiotic stress conditions like salinity or drought. In present study, we have explored the effect of mechanical stress on the growth of Glycine max (soybean) seedlings and studied its effect on tolerance to salinity stress. Regular mechanical stress given in the form of touch suppressed overall growth of the soybean seedlings. Touch pre-treated seedlings were further treated with sodium chloride to test for its tolerance to salinity. Upon salt treatment, we observed comparatively higher survival rate and more growth in the seedlings that received regular mechanical stress during early growth stages. The adaptations to mechanical stress given at the early-stage of growth may have led to the enhanced tolerance to salinity stress experienced in later growth stage

Investigation of Wound Incidence on Stem Surface in Soybean Seedling

Investigation of Wound Incidence on Stem Surface in Soybean Seedling

Cadmium affects the growth, antioxidant capacity, chlorophyll content, and homeostasis of essential elements in soybean plants

Soybean (Glycine max L.), as an oil and protein crop, has attracted interest for its potential in the reclamation/restoration of barren and contaminated habitats due to its ability to tolerate adverse environments. To investigate the effects of the growth (biomass and plant height), chlorophyll content, antioxidative capacity (peroxidase and superoxide dismutase activities), and homeostasis of essential elements in soybean plants induced by cadmium (Cd), a pot experiment was performed. Soybean seeds were cultivated in six different levels of Cd-contaminated soil (0, 0.25, 0.50, 1.00, 2.50, 5.00, and 10.00 mg kg−1) for 27 days at 60 % humidity and 25–35 °C in a greenhouse with natural light. Soybean seedling growth was stimulated and inhibited at low (≤1.00 mg kg−1) and high (≥2.50 mg kg−1) Cd concentrations, respectively. Essential metal elements (Mg, Fe, and Zn) and chlorophyll contents of leaves were increased and decreased at low and high Cd concentrations, respectively. Exposure to high Cd concentrations interfered with the homeostasis of essential elements in soybean plants. High Cd concentrations reduced antioxidant capacity and chlorophyll content, which inhibited soybean growth. The Cd accumulation level (>100 mg kg−1) in soybean plant organs was unsafe for producing soybean products. However, soybean seedlings appear to tolerate moderate Cd contamination.

Integrated transcriptomic and metabolomic analyses reveal the toxic effects of dimethoate on green vegetable soya bean seedlings

The insecticide dimethoate, an organophosphate, has been used on crops, soybeans, fruits, and vegetables since the 1960s and is considered one of the most widely used pesticides. However, the understanding of the molecular mechanisms of dimethoate in crops, especially crop seedlings, is still limited. The green vegetable soya bean (Glycine max merr) is usually used as a vegetable-like fruit of soybean in many Asian countries. This study aimed to analyze the effect of dimethoate on the growth of green vegetable soya bean seedlings at the metabolic and transcriptional levels. An integrated analysis of the transcriptome and metabolome was performed to determine the responses of green vegetable soya bean seedlings to different concentrations (D1 for low dose, D2 for high dose and C for control) of dimethoate. In omics analyses, 4156 differentially expressed genes (DEGs) and 1935 differentially abundant metabolites (DAMs) were identified in the D1/C comparison, and 11,162 DEGs and 819 DAMs were identified in D2/C. Correlation analyses revealed dimethoate affected the metabolic pathways of green vegetable soya beans such as the biosynthesis of secondary metabolites and microbial metabolism in diverse environmental pathways, demonstrating that even small doses of dimethoate can affect green vegetable soya bean seedlings in a short period of time. Our study further enriches our understanding of the molecular mechanisms by which green vegetable soya beans are treated with dimethoate and provides a deeper understanding of the effects of dimethoate on crops.

Metabolic insights into how multifunctional microbial consortium enhances atrazine removal and phosphorus uptake at low temperature

Agricultural soils in the black soil region of northeast China often face negative stress due to low temperatures, pesticide contamination, and inadequate nutrient supply. In this study, a new cold-tolerant strain of Peribacillus simplex C1 (C1) was selectively isolated from atrazine contaminated soil. The artificially constructed microbial consortium (CPD) [C1, phosphorus-solubilizing bacterium Enterobacter sp. P1, and atrazine-degrading bacterium Acinetobacter lwoffii DNS32] demonstrated the most effective performance in enhancing atrazine degradation and phosphorus-solubilizing capacity when the initial inoculation ratio of 5:1:2 at 15 °C. CPD enhanced energy-related metabolic pathways and increased choline production to regulate bacterial adaptation to temperature decrease. Additionally, the strains could selectively utilize carbon sources (low molecular weight organic acids) or nitrogen sources (some metabolites of atrazine) provided by each other to enhance growth. Furthermore, strain C1 enhanced membrane fluidity through increased expression of the unsaturated fatty acids. Pot experiments demonstrated that CPD assisted soybean seedlings in resisting dual stresses of low temperature and atrazine contamination by inducing the expression of genes related to photosynthesis, membrane permeability, phosphorus response, and cold tolerance.

Effects of Combined Stress of Polyethylene and Sulfamethazine on Seed Germination, Seedling Growth, and Physiological Characteristics of Soybean

The combined pollution of antibiotics adsorption by microplastics has become inevitable in soil ecosystems; moreover, the plant biological effects under combined stress remain unclear. This study used soybean variety Jindou 21 as the material and conducted seed germination test and soil-potted seedling experiment to study the effects of different single and combined treatments of polyethylene (PE) and sulfamethazine (SMZ) on seed germination, seedling growth, photosynthetic parameters, chlorophyll fluorescence parameters, and nitrogen metabolism. The results showed that single PE treatment at low levels promoted soybean seed germination and seedling growth physiology; however, inhibited them at a high level. A lower-level PE treatment[10 mg·L-1 (or mg·kg-1)] could promote soybean seed germination, seedling growth, photosynthesis, and nitrogen metabolism, whereas a higher level PE treatment[100 mg·L-1 and 200 mg·L-1 (or mg·kg-1)] had significant inhibition. The single SMZ treatment had different degrees of inhibition on soybean seed germination and seedling growth physiology, and the inhibition degree increased with the increase in SMZ treatment level. Under the different levels of combined treatments of PE and SMZ, adding the lower level PE treatment could alleviate the inhibition of the single SMZ treatment on soybean, with 10 mg·L-1(or mg·kg-1) PE+1 mg·L-1(or mg·kg-1) SMZ treatment having the best comprehensive mitigation effect, which could increase soybean seed germination potential, germination rate, germination index, vigor index, plant height, root length, shoot and root fresh weight, Pn, Gs, Tr, chlorophyll contents, Fv/Fm, ΦPSⅡ, ETR, qP, and key enzyme activities for nitrogen metabolism such as NR and decrease the average germination time, Ci, NPQ, and NO3--N and NH4+-N contents compared with those in the single SMZ treatment. Adding the higher level PE treatment enhanced the inhibition of SMZ on soybean, and the inhibition degree increased with the increase in SMZ treatment level, in which 200 mg·L-1(or mg·kg-1) PE+50 mg·L-1(or mg·kg-1) SMZ treatment yielded the greatest inhibition. In summary, the lower level PE treatment could alleviate the inhibition of SMZ on soybean seeds and seedlings to a certain extent; however, the higher level PE treatment could produce a synergistic effect with SMZ, thus aggravating the toxic effect of the single stress treatment.

Molecular evidence for enhancer-promoter interactions in light responses of soybean seedlings.

Interactions of enhancers with promoters and transcription factors mediate chromatin loop formation to regulate downstream gene expression in response to environmental stimuli such as light.

Graphitic carbon nitride nanosheets mitigate cadmium toxicity in Glycine max L. by promoting cadmium retention in root and improving photosynthetic performance

Cadmium (Cd) pollution poses a serious threat to plant growth and yield. Nanomaterials have shown great application potential for alleviation of Cd toxicity to plants. In this study, we applied graphitic carbon nitride nanosheets (g-C3N4 NSs) for alleviation of Cd-toxicity to soybean (Glycine max L.). The g-C3N4 NSs supplementation significantly improved plant growth and reduced oxidative damage in the Cd-toxicated soybean seedlings through hydroponic culture. Particularly, the g-C3N4 NSs dynamically regulated the root cell wall (RCW) components by increasing pectin content and modifying its demethylation via enhancing pectin methylesterase (PME) activity, therefore greatly enhanced stronger RCW-Cd retention (up to 82.8%) and reduced Cd migration to the shoot. Additionally, the g-C3N4 NSs reversed the Cd-induced chlorosis, increased photosynthetic efficiency because of enhancement in Fv/Fm ration, Y(II) and sugars content. These results provide new insights into the alleviation of Cd toxicity to plants by g-C3N4 NSs, and shed light on the application of low-cost and environmental-friendly carbon-based NMs for alleviating heavy metal toxicity to plants.

The content of soluble carbohydrates and proteins in the seedlings of soybean varieties with contrast photoperiodic response under the influence of selective light

Aim. Study of the influence of selective light irradiation on the content of soluble carbohydrates and proteins in the axial organs of seedlings of soybean varieties with a contrasting photoperiodic response (PPR). Methods. As plant material we used etiolated seedlings of soybean (Glycine max (L.) Merr.) SDP Khadjibei variety and DNP Yatran variety. Etiolated seedlings were irradiated daily for 30 minutes (5 days) using LED matrices with red, green and blue light. Then the material was fixed and a biochemical analysis was carried out in the axial organs of the seedlings – the content of soluble carbohydrates and proteins was determined. Results. GL and BL irradiation had the maximum effect on the content of soluble carbohydrates in SDP soybean seedlings of Khadjibey variety. In soybean seedlings of the DNP Yatran variety a significant effect was exerted by the action of all studied spectra, which was manifested in a decrease in their content in the above-ground part and growth in the root system. The content of proteins in seedlings of both varieties under the influence of selective light increased in both parts of the seedling. The most significant effect was observed for the irradiation of GL. Conclusions. The effects of selective light irradiation are manifested differently in shoots and roots, which may be due to the different composition or activity of the photoreceptor systems of the axial organs.

Growth Response of Two Soybean (Glycine Max (L.) Merr) Varieties Denna 1 And Rajabasa Subjected to Radiation Mutation Technique

One of the national initiatives to lessen reliance on imports of soybeans and attain soybean self-sufficiency by 2022 is soybean production. Gamma rays are used to irradiate the Denna 1 and Rajabasa kinds of soybean seedlings. The treatments utilized were planted in metal trays and varied from 0 to 1000 Gy. The germination rate was 40% in Rajabasa at 900 and 1000 Gy, which was the lowest, and 88.35% at 0 Gy on Denna 1. Denna 1 had the highest plant height at 0 Gy (34.53 cm), while Denna 2 had the lowest at 800 Gy (1.30 cm). Denna 1 had the most leaves (6.40 cm) at 200 Gy, whereas Rajabasa had the fewest at 400 Gy (0.50). Rajabasa-2 had the highest flowering age at M3 generation (44,33 days) and Denna-1.3 had the lowest (300 Gy) (41,67 days). Rajabasa mutant line had the maximum weight of full pods at 200 Gy (55,33 g), whereas Rajabasa-1 showed the lowest weight at 300 Gy (33 g). The outcome of this dosage orientation experiment may assist in determining the ideal dose for post-irradiated plants.

Agricultural tillage practice and rhizosphere selection interactively drive the improvement of soybean plant biomass.

Rhizosphere microbes play key roles in plant growth and productivity in agricultural systems. One of the critical issues is revealing the interaction of agricultural management (M) and rhizosphere selection effects (R) on soil microbial communities, root exudates and plant productivity. Through a field management experiment, we found that bacteria were more sensitive to the M × R interaction effect than fungi, and the positive effect of rhizosphere bacterial diversity on plant biomass existed in the bacterial three two-tillage system. In addition, inoculation experiments demonstrated that the nitrogen cycle-related isolate Stenotrophomonas could promote plant growth and alter the activities of extracellular enzymes N-acetyl- d-glucosaminidase and leucine aminopeptidase in rhizosphere soil. Microbe-metabolites network analysis revealed that hubnodes Burkholderia-Caballeronia-Paraburkholderia and Pseudomonas were recruited by specific root metabolites under the M × R interaction effect, and the inoculation of 10 rhizosphere-matched isolates further proved that these microbes could promote the growth of soybean seedlings. Kyoto Encyclopaedia of Genes and Genomes pathway analysis indicated that the growth-promoting mechanisms of these beneficial genera were closely related to metabolic pathways such as amino acid metabolism, melatonin biosynthesis, aerobactin biosynthesis and so on. This study provides field observation and experimental evidence to reveal the close relationship between beneficial rhizosphere microbes and plant productivity under the M × R interaction effect.

An Ensemble Learning Model for Detecting Soybean Seedling Emergence in UAV Imagery.

Efficient detection and evaluation of soybean seedling emergence is an important measure for making field management decisions. However, there are many indicators related to emergence, and using multiple models to detect them separately makes data processing too slow to aid timely field management. In this study, we aimed to integrate several deep learning and image processing methods to build a model to evaluate multiple soybean seedling emergence information. An unmanned aerial vehicle (UAV) was used to acquire soybean seedling RGB images at emergence (VE), cotyledon (VC), and first node (V1) stages. The number of soybean seedlings that emerged was obtained by the seedling emergence detection module, and image datasets were constructed using the seedling automatic cutting module. The improved AlexNet was used as the backbone network of the growth stage discrimination module. The above modules were combined to calculate the emergence proportion in each stage and determine soybean seedlings emergence uniformity. The results show that the seedling emergence detection module was able to identify the number of soybean seedlings with an average accuracy of 99.92%, a R2 of 0.9784, a RMSE of 6.07, and a MAE of 5.60. The improved AlexNet was more lightweight, training time was reduced, the average accuracy was 99.07%, and the average loss was 0.0355. The model was validated in the field, and the error between predicted and real emergence proportions was up to 0.0775 and down to 0.0060. It provides an effective ensemble learning model for the detection and evaluation of soybean seedling emergence, which can provide a theoretical basis for making decisions on soybean field management and precision operations and has the potential to evaluate other crops emergence information.

Root System Architecture and Physiological Characteristics of Soybean (Glycine max L.) Seedlings in Response to PEG6000-Simulated Drought Stress

The production of soybean is restricted in sub-Saharan Africa by several stress conditions, including drought because its production is exclusively rain-fed. Identifying drought resistant varieties is of paramount importance. Thus, the objectives of this work were to (i) evaluate the effect of polyethylene glycol 6000 (PEG6000) on soybean at the seedling stage, (ii) determine the root system architecture and physiological characters to water deficit stress, and (iii) establish the correlation among the quantitative variables responsible for drought tolerance in soybean varieties. Twenty soybean accessions (G1 to G20) were subjected to 10% PEG6000 concentration at seedling stages under a controlled environment using a randomized complete block design with 3 replicates. Vegetative growth data were collected. Highly significant differences P < 0.0001 of proline, carotenoid, chlorophyll a, and chlorophyll b contents were recorded among the 20 accessions in response to PEG application. G16 and G19 had the highest carotenoid, highest chlorophyll a, and chlorophyll b. The highest dry weight was observed in G16 and G10, while the number of leaves was recorded in G19 and G17. G4, G9, G10, and G13 demonstrated the highest dry weight. The PEG-simulated drought stress reduced the average root diameters and the number of lateral roots of all 20 accession plants. G1, G3, G4, G8, G9, and G15 had the longest roots than the control plants as a mechanism to withstand drought stress by seeking water in the deep. Number of leaves was significantly and positively correlated with shoot dry weight, root dry weight, and root diameter but was significantly and negatively correlated with canopy wilting. Proline content was significantly and positively correlated with carotenoid, chlorophyll content, chlorophyll a, and chlorophyll b. G10, G19, G9, G6, G16, G17, G20, G16, and G18 are the tolerant cultivars to drought stress on the basis of growth, physiological, and root system architecture.

Effect of nitrogen application levels on photosynthetic nitrogen distribution and use efficiency in soybean seedling leaves

BackgroundNitrogen nutrition is strongly associated with crop growth and development. Nitrogen application level affects leaf size as well as nitrogen content and distribution, and thus affects photosynthetic nitrogen-use efficiency (PNUE) and yield. In this study, soybean varieties “Jinyuan 55” and “Keshan 1” were treated with nitrogen as urea at: N0, 0 kg hm−2; N0.5, 60 kg hm−2; N1, 120 kg hm−2; and N1.5, 180 kg hm−2. We compared the effect of nitrogen level on plant morphology, biomass, photosynthetic physiology, nitrogen distribution, PNUE, and other soybean seedling leaf characteristics. ResultsMaximum carboxylation and electron transfer, net photosynthetic rates, and PNUE of both soybean varieties showed initial significant increases with increasing nitrogen application rate and subsequent stabilization. PNUE, carboxylation system components, electron transport components, and non-photosynthetic system distribution ratios in the photosynthetic system increased and subsequently decreased with increased nitrogen application rate. The nitrogen ratio between carboxylation and electron transport systems was positively correlated with PNUE in both soybean varieties. The nitrogen ratio in light-harvesting and non-photosynthetic systems showed a linear negative correlation with PNUE. ConclusionsOverall, an appropriate nitrogen level maintained a high photosynthetic nitrogen ratio, whereas low- or high-nitrogen conditions increased or decreased the nitrogen ratio in non-photosynthetic and photosynthetic systems, respectively, thus decreasing the PNUE and photosynthetic capacity. Moreover, increased nitrogen application rate led to a decreased nitrogen ratio in the light-harvesting system and an increased nitrogen ratio of electron transport and carboxylation systems. Our results provide a theoretical basis for optimizing leaf nitrogen distribution, determining optimum nitrogen levels, and promoting soybean seedling growth.

Exogenous application of stevioside enhances root growth promotion in soybean (Glycine max (L.) Merrill)

The present study aims to investigate the impact of externally applied stevioside (a sugar-based glycoside) on soybean root growth by examining morpho-physiological characteristics, biochemical parameters, and gene expression. Soybean seedlings (10-day-old) were treated with stevioside (0, 8.0 μM, 24.5 μM, and 40.5 μM) for four times at six days’ intervals by soil drenching. Treatment with 24.5 μM stevioside significantly increased root length (29.18 cm plant−1), root numbers (38.5 plant−1), root biomass (0.95 g plant−1 FW; 0.18 g plant−1 DW), shoot length (30.96 cm plant−1), and shoot biomass (2.14 g plant−1 FW; 0.36 g plant−1 DW) compared to the control. Moreover, 24.5 μM of stevioside was effective in enhancing photosynthetic pigments, leaf relative water content, and antioxidant enzymes compared to control. Conversely, plants exposed to a higher concentration of stevioside (40.5 μM), elevated total polyphenolic content, total flavonoid content, DPPH activity, total soluble sugars, reducing sugars, and proline content. Furthermore, gene expression of root growth development-related genes such as GmYUC2a, GmAUX2, GmPIN1A, GmABI5, GmPIF, GmSLR1, and GmLBD14 in stevioside-treated soybean plants were evaluated. Stevioside (8.0 μM) showed significant expression of GmPIN1A, whereas, 40.5 μM of stevioside enhanced GmABI5 expression. In contrast, most of the root growth development genes such as GmYUC2a, GmAUX2, GmPIF, GmSLR1, and GmLBD14, were highly expressed at 24.5 μM of stevioside treatment. Taken together, our results demonstrate the potential of stevioside in improving morpho-physiological traits, biochemical status, and the expression of root development genes in soybean. Hence, stevioside could be used as a supplement to enhance plant performance.