The impact of combined application of biochar and fertilizer on the biochemical properties of soil in soybean fields.

Background: Heilongjiang Province is a major soybean production area in China. To improve soil structure and increase soybean yield, this study examined the effects of combined biochar and chemical fertilizer application on the biochemical properties of soil in a maize-soybean rotation system. Methods: The research were conducted from 2021 to 2022 at Heshan Farm Science Park in Heilongjiang Province, this field plot experiment utilized two soybean varieties, Heihe 43 (a high-protein variety) and Keshan 1 (a high-oil variety). In 2021, two plots with similar fertility levels were selected for planting soybeans and maize. In 2022, a maize-soybean rotation was implemented with five treatments: conventional fertilization (CK), increased biochar+reduced fertilizer 1 (F1+B), reduced fertilizer 1 (F1), increased biochar+reduced fertilizer 2 (F2+B), and reduced fertilizer 2 (F2). The study systematically analyzed the effects of combined biochar and chemical fertilizer application on soil chemical properties and microbial characteristics. Results: Over 2 years, results showed that combined application effectively improved soil chemical traits. Compared to conventional fertilization (CK) and reduced fertilization (F1, F2), t he combined application of biochar and chemical fertilizer (F1+B, F2+B) increased soil pH, EC and the absolute value of zeta potential of soil surface, the CEC of soil significantly increased by 15.6-44.3%, the soil surface charge density and the soil surface charge quantity significantly increased by 16.4-73.5%. The combined application of biochar and chemical fertilizer also effectively enhanced the abundance and diversity of soil microbes. Dominant bacterial groups in soybean field soils under different treatments included Actinobacteria, Acidobacteria, Chloroflexi, and Proteobacteria; while dominant fungal groups were Ascomycota, Basidiomycota, and Mortierellomycota. Alpha and Beta diversity analyses revealed that the F1+B treatment significantly enhanced the species richness and diversity of bacteria and fungi in the soil, increasing the proportion and evenness of dominant and beneficial genera.

Distribution characteristics of soil moisture and temperature under different land use types in the deep profile of loess area in northern Shaanxi, China.

Understanding the effects of different land use modes on the spatial and temporal variations of soil moisture and temperature in the deep profile and revealing the regulatory effects of various vegetation covers on regional water and heat resources can provide a theoretical basis for the optimization of land management and vegetation restoration. Taking the advantage of different land use patterns in the Liudaogou watershed in the northern part of Loess Plateau, we monitored soil moisture content as well as temperature in the 0-1000 cm soil layer in 2022 to analyze the temporal variation and vertical profile distribution characteristics of soil moisture and temperature under four land use modes (woodland, grassland, farmland, and wild grassland). The results showed that soil moisture and temperature distributions varied significantly across different land use types. In the growing season (April-October), total soil water storage in the 0-1000 cm soil layer of the four land use types, in a descending order, was as follows: soybean farmland (1393 mm), wild grassland (1374 mm), Caragana korshinkii forest (1218 mm), and alfalfa grassland (557 mm). Soil moisture of C. korshinkii forest and soybean farmland changed obviously in the 0-300 cm soil layer, and that of wild grassland and alfalfa grassland was in 0-500 and 0-200 cm soil layers, respectively, while soil moisture of deep soil layers fluctuated little. The impact of land use modes on soil temperature was primarily manifested in the 0-200 cm soil layer, and the depth was up to 300 cm. The depth of precipitation infiltration replenishment of the four land use modes was approximately 200 cm. The depth of soil moisture depletion was 200 cm in both C. korshinkii forest and alfalfa grassland, and was 100 cm in soybean farmland and wild grassland. Soil hydrothermal processes in the deep profile varied across vegetation types.

The Reverse Ecology-Based Approach to Design a Bacterial Consortium as Soybean Bioinoculant.

Bioinoculants traditionally rely on selecting efficient microbes from the soil with potential growth-enhancing traits for plants. However, such approaches often neglect microbe-microbe and microbe-plant interactions. In this study, we applied a reverse ecology framework to design and assess a bacterial consortium tailored for soybeans. Our analysis identified Paenibacillus polymyxa, Methylobacterium brachiatum, and Enterobacter sp. as key strains for their synergistic potential in promoting soybean growth. Computational analyses revealed that these selected strains exhibited low competitiveness and metabolic compatibility. Specifically, their complementary metabolic profiles suggested minimal competition for resources and potential for mutualistic interactions. In vitro experiments further supported these findings, demonstrating that the consortium maintained stable growth without inhibitory effects among strains. In addition, greenhouse validation experiments confirmed the efficacy of the microbial consortium in enhancing soybean growth such as root and shoot development and biomass production. Overall, this study underscores the potential of reverse ecology in optimizing microbial consortia design for bioinoculant applications.

Climate change effects on the diversity and distribution of soybean true bugs pests.

BACKGROUND: Climate change and pests are two major factors in the reduction of global soybean yields. The diversity and geographic distribution of soybean true bug pests vary across soybean production areas worldwide, and climate change impacts are different across species and regions. Therefore, we integrated spatial and temporal predictions at the global scale to predict the impact of global warming on the distribution of 84 soybean true bug pests by the maximum entropy niche model (MaxEnt) under present (1970-2000) and future (2041-2060) scenarios. We produced an ensemble projection of the potential distribution of pests and crop production areas to estimate how and where climate warming will augment the threat of soybean true bug pests to soybean production areas. RESULTS: Our results indicated that Southeast North America, Central South America, Europe and East Asia were the regions with the higher richness of soybean true bug and the most vulnerable areas to invasion threats. Climate change would promote the expansion of the distribution range and facilitate pest movement pole wards, affecting more soybean cultivated areas located in mid-latitudes. Moreover, species with different distribution patterns responded differently to climate change in that large-ranged species tended to increase in occupancy over time, whereas small-ranged species tended to decrease. CONCLUSION: This result indicates that some pests that have not yet become notable may have the chance to develop into serious pests in the future due to the expansion of their geographical range. Our findings highlight that soybean cultivated regions at mid-latitudes would face general infestations from soybean true bug pests under global warming. These results will further facilitate the formulation of adaptation planning to minimize local environmental impacts in the future. © 2024 Society of Chemical Industry.

Assessment of genetic diversity by phenological traits, field performance, and Start Codon Targeted (SCoT) polymorphism marker of seventeen soybean genotypes (Glycine max L.).

The Egyptian-farmed soybeans have a wide range of genetic diversity which is most important in plant improvement programs in order to develop new higher yielding soybean genotypes. The present study is designed to determine the genetic variability among seventeen genotypes of cultivated soybean (Glycine max L.) by examining the phenotypic level at the seedling stage, field performance over two years 2022/2023 and genetically using Start Codon Targeted (SCoT) markers. Results indicated that the SCoT markers, 100 seed weight, and tip angle (TA) traits were positively correlated with H2L12, DR 101, H15L5, and H117 genotypes. In addition, the number of branches per plant and plant height were associated with H113, H32, Crowford, H129, and D7512035. Furthermore, the length of the first internode (LFI), root width (RW), root length (RL), and shoot length (SL) were more associated with Giza 111, NC105, and Hutcheson. The hierarchical cluster analysis (HCA) and its associated heatmap explored the differences among the genotypes. It showed that all examined parameters were clustered into four distinct clusters. The obtained results showed that genotypes NC105, H30, D75_12035, and H2L12 have promising phenological and morphological traits besides tracking the inheritance of nearby genes surrounding the ATG translation start codon since they are in a monoclades. The obtained results will help the breeder plan appropriate selection strategies for improving seed yield in soybeans through hybridization from divergent clusters.

Machine learning-based analysis of nutrient and water uptake in hydroponically grown soybeans.

Recent advancements in sustainable agriculture have spurred interest in hydroponics as an alternative to conventional farming methods. However, the lack of data-driven approaches in hydroponic growth presents a significant challenge. This study addresses this gap by varying nitrogen, magnesium, and potassium concentrations in hydroponically grown soybeans and conducting essential nutrient profiling across the growth cycle. Statistical techniques like Linear Interpolation are employed to interpolate nutrient data and a feature selection pipeline consisting of chi-squared testing methods, Linear Regression with Recursive Feature Elimination (RFE) and ExtraTreesClassifier have been used to select important nutrients for predicting water uptake using non-parametric regression methods. For different nutrient growth media, i.e. for soybeans grown in Hoagland + Nitrogen and Hoagland + Magnesium media, the Random Forest regressor outperformed other methods in predicting water uptake, achieving testing Mean Squared Error (MSE) scores of 24.55 ( R 2 score 0.63) and 8.23 ( R 2 score 0.81), respectively. Similarly, for soybeans grown in Hoagland + Potassium media, Support Vector Regression demonstrated superior performance with a testing MSE of 4.37 and R 2 score of 0.85. SHapley Additive exPlanations (SHAP) values are examined in each case to elucidate the contributions of individual nutrients to water uptake predictions. This research aims to provide data-driven insights to optimize hydroponic practices for sustainable food production.

Photosynthetic characteristics and genetic mapping of a yellow-green leaf mutant jym165 in soybean.

BACKGROUND: Leaves are important sites for photosynthesis and can convert inorganic substances into organic matter. Photosynthetic performance is an important factor affecting crop yield. Leaf colour is closely related to photosynthesis, and leaf colour mutants are considered an ideal material for studying photosynthesis. RESULTS: We obtained a yellow-green leaf mutant jym165, using ethyl methane sulfonate (EMS) mutagenesis. Physiological and biochemical analyses indicated that the contents of chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll in the jym165 mutant decreased significantly compared with those in Jiyu47 (JY47). The abnormal chloroplast development of jym165 led to a decrease in net photosynthetic rate and starch content compared with that of JY47. However, quality traits analysis showed that the sum of oil and protein contents in jym165 was higher than that in JY47. In addition, the regional yield (seed spacing: 5 cm) of jym165 increased by 2.42% compared with that of JY47 under high planting density. Comparative transcriptome analysis showed that the yellow-green leaf phenotype was closely related to photosynthesis and starch and sugar metabolism pathways. Genetic analysis suggests that the yellow-green leaf phenotype is controlled by a single recessive nuclear gene. Using Mutmap sequencing, the candidate regions related of leaf colour was narrowed to 3.44 Mb on Chr 10. CONCLUSIONS: Abnormal chloroplast development in yellow-green mutants leads to a decrease in the photosynthetic pigment content and net photosynthetic rate, which affects the soybean photosynthesis pathway and starch and sugar metabolism pathways. Moreover, it has the potentiality to increase soybean yield under dense planting conditions. This study provides a useful reference for studying the molecular mechanisms underlying photosynthesis in soybean.

Quality traits drive the enrichment of Massilia in the rhizosphere to improve soybean oil content.

BACKGROUND: Soybean seeds are rich in protein and oil. The selection of varieties that produce high-quality seeds has been one of the priorities of soybean breeding programs. However, the influence of improved seed quality on the rhizosphere microbiota and whether the microbiota is involved in determining seed quality are still unclear. Here, we analyzed the structures of the rhizospheric bacterial communities of 100 soybean varieties, including 53 landraces and 47 modern cultivars, and evaluated the interactions between seed quality traits and rhizospheric bacteria. RESULTS: We found that rhizospheric bacterial structures differed between landraces and cultivars and that this difference was directly related to their oil content. Seven bacterial families (Sphingomonadaceae, Gemmatimonadaceae, Nocardioidaceae, Xanthobacteraceae, Chitinophagaceae, Oxalobacteraceae, and Streptomycetaceae) were obviously enriched in the rhizospheres of the high-oil cultivars. Among them, Oxalobacteraceae (Massilia) was assembled specifically by the root exudates of high-oil cultivars and was associated with the phenolic acids and flavonoids in plant phenylpropanoid biosynthetic pathways. Furthermore, we showed that Massilia affected auxin signaling or interfered with active oxygen-related metabolism. In addition, Massilia activated glycolysis pathway, thereby promoting seed oil accumulation. CONCLUSIONS: These results provide a solid theoretical basis for the breeding of revolutionary soybean cultivars with desired seed quality and optimal microbiomes and the development of new cultivation strategies for increasing the oil content of seeds. Video Abstract.

Design and test of reel speed control system for soybean combine harvester in the strip intercropping mode.

At present, the speed of the reel of soybean combine harvester is mainly adjusted manually, and basically does not have the ability to automatically adjust the speed of the reel according to changes in crops or working speed. In the maize-soybean strip intercropping mode, soybean plants are densely planted. During harvesting, the feeding rate increases, making it even more necessary to adjust the reel speed according to the growth status of the crops. This article uses PLC as the main control platform to design a reel speed control system for the existing combine harvester. Tests have shown that the control system can meet the requirements for reel speed control. The relative error of the reel control system's speed test is 2.6%, the relative error of the operating speed is 6.77%, and the maximum relative error of the automatic control of the reel speed is 5.38%. Compared with traditional reel, it reduces header loss by 2.12%. The soybean combine harvester reel speed control system designed in this article can realize automatic adjustment of the reel speed, reduce feeding losses caused by changes in crop height, changes in feed volume, and untimely adjustment of the reel, and can reduce header loss, increased crop yield.

Impact of Sulfur Deficiency and Excess on the Growth and Development of Soybean Seedlings.

Sulfur is a critical element for plant growth and development, serving as a component of amino acids (cysteine and methionine), iron-sulfur clusters, proteins, glutathione, coenzymes, and auxin precursors. Deficiency or low concentrations of sulfur in the soil can lead to significant growth retardation in plants. The objective of our study was to examine the effects of sulfur (S) deficiency and excess on morphological symptoms, sulfur and nitrogen (N) metabolism, as well as antioxidant activity in soybean. We found that S starvation decreased the fine root length, biomass, and activity, and the chlorophyll content was reduced, while excess sulfur promotes lateral root growth. In contrast to sulfur excess, sulfur deficiency inhibits N and S metabolism levels in both subsurface and above-ground parts, and induced the expression of some sulfur transporters (SULTRs). In this study, we created soybean hairy root lines overexpressing the SULTR gene (GmSULTR2;1a) to observe metabolic changes following sulfur deficiency treatment. The results showed that GmSULTR2;1a saved the sulfur-deficient phenotype, and the antioxidant enzyme activity was much higher than that of the wildtype in the absence of sulfur. Our study revealed the important role of sulfur element in soybean growth and development and the regulation of sulfur deficiency by GmSULTR2;1a.

Genome-Wide Association study for root system architecture traits in field soybean [Glycine max (L.) Merr.].

Roots play a crucial role in plant development, serving to absorb water and nutrients from the soil while also providing structural stability. However, the impacts of global warming can impede root growth by altering soil conditions that hinder overall plant growth. To address this challenge, there is a need to screen and identify plant genotypes with superior Root System Architecture traits (RSA), that can be used for future breeding efforts in enhancing their resilience to these environmental changes. In this project, 500 mid to late-maturity soybean accessions were grown on blue blotting papers hydroponically with six replicates and assessed seven RSA traits. Genome-Wide Association Studies (GWAS) were carried out with root phenotypic data and SNP data from the SoySNP50K iSelect SNP BeadChip, using both the TASSEL 5.0 and FarmCPU techniques. A total of 26 significant SNP-trait correlations were discovered, with 11 SNPs on chromosome 13. After SNP selection, we identified 14 candidate genes within 100-kb regions flanking the SNPs, which are related to root architecture. Notably, Glyma.17G258700, which exhibited substantial differential expression in root tips and its Arabidopsis homolog, AT4G24190 (GRP94) is involved in the regulation of meristem size and organization. Other candidate genes includes Glyma.03G023000 and Glyma.13G273500 that are also play a key role in lateral root initiation and root meristem growth, respectively. These findings significantly contribute to the discovery of key genes associated with root system architecture, facilitating the breeding of resilient cultivars adaptable to changing climates.

Does Rhizobial Inoculation Change the Microbial Community in Field Soils? A| |Comparison with Agricultural Land-use Changes.

Although microbial inoculation may be effective for sustainable crop production, detrimental aspects have been argued because of the potential of inoculated microorganisms to behave as invaders and negatively affect the microbial ecosystem. We herein compared the impact of rhizobial inoculation on the soil bacterial community with that of agricultural land-use changes using a 16S rRNA amplicon ana-lysis. Soybean plants were cultivated with and without five types of bradyrhizobial inoculants (Bradyrhizobium diazoefficiens or Bradyrhizobium ottawaense) in experimental fields of Andosol, and the high nodule occupancy (35-72%) of bradyrhizobial inoculants was confirmed by nosZ PCR. However, bradyrhizobial inoculants did not significantly affect Shannon's diversity index (α-diversity) or shifts (ß-diversity) in the bacterial community in the soils. Moreover, the soil bacterial community was significantly affected by land-use types (conventional cropping, organic cropping, and original forest), where ß-diversity correlated with soil chemical properties (pH, carbon, and nitrogen contents). Therefore, the effects of bradyrhizobial inoculation on bacterial communities in bulk soil were minor, regardless of high nodule occupancy. We also observed a correlation between the relative abundance of bacterial classes (Alphaproteobacteria, Gammaproteobacteria, and Gemmatimonadetes) and land-use types or soil chemical properties. The impact of microbial inoculation on soil microbial ecosystems has been exami-ned to a limited extent, such as rhizosphere communities and viability. In the present study, we found that bacterial community shifts in soil were more strongly affected by land usage than by rhizobial inoculation. Therefore, the results obtained herein highlight the importance of assessing microbial inoculants in consideration of the entire land management system.

Deciphering the genetic basis of salinity tolerance in a diverse panel of cultivated and wild soybean accessions by genome-wide association mapping.

KEY MESSAGE: In a genome-wide association study involving 269 cultivated and wild soybean accessions, potential salt tolerance donors were identified along with significant markers and candidate genes, such as GmKUP6 and GmWRKY33. Salt stress remains a significant challenge in agricultural systems, notably impacting soybean productivity worldwide. A comprehensive genome-wide association study (GWAS) was conducted to elucidate the genetic underpinnings of salt tolerance and identify novel source of salt tolerance among soybean genotypes. A diverse panel comprising 269 wild and cultivated soybean accessions was subjected to saline stress under controlled greenhouse conditions. Phenotypic data revealed that salt tolerance of soybean germplasm accessions was heavily compromised by the accumulation of sodium and chloride, as indicated by highly significant positive correlations of leaf scorching score with leaf sodium/chloride content. The GWAS analysis, leveraging a dataset of 32,832 SNPs, unveiled 32 significant marker-trait associations (MTAs) across seven traits associated with salt tolerance. These markers explained a substantial portion of the phenotypic variation, ranging from 14 to 52%. Notably, 11 markers surpassed Bonferroni's correction threshold, exhibiting highly significant associations with the respective traits. Gene Ontology enrichment analysis conducted within a 100 Kb range of the identified MTAs highlighted candidate genes such as potassium transporter 6 (GmKUP6), cation hydrogen exchanger (GmCHX15), and GmWRKY33. Expression levels of GmKUP6 and GmWRKY33 significantly varied between salt-tolerant and salt-susceptible soybean accessions under salt stress. The genetic markers and candidate genes identified in this study hold promise for developing soybean varieties resilient to salinity stress, thereby mitigating its adverse effects.

Identification of quantitative trait loci for lodging and related agronomic traits in soybean (Glycine max [L.] Merr.).

BACKGROUND: Lodging, a crucial agronomic trait linked to soybean yield, poses a significant challenge in soybean production. Nevertheless, there has been less research on soybean lodging compared to other important agronomic traits, hindering progress in breeding high-yield soybeans. Our goals were to investigate lodging, pinpoint quantitative trait loci (QTL) linked to lodging, and forecast potential candidate genes linked to this trait. To achieve this, we employed a recombinant inbred line (RIL) population derived from a cross between Guizao 1 and B13 (GB) across various environments. RESULTS: The lodging score of the RIL population was found to be significantly positively correlated with flowering time, maturity time, plant height, number of main stem nodes, stem diameter, and internode length, with correlation coefficients ranging from 0.457 to 0.783. A total of 84 QTLs associated with soybean lodging and related traits were identified using the GB population. The contribution of phenotypic variance ranged from 1.26 to 66.87%, with LOD scores ranging from 2.52 to 69.22. Additionally, within these QTLs, a stable major QTL associated with lodging was newly discovered in the GB population. Out of the ten major QTLs associated with other related traits, nine of them were situated within the qLD-4-1 interval of the major lodging score locus, displaying phenotypic variations ranging from 12.10 to 66.87%. Specific alterations in gene expression were revealed through the analysis of resequencing data from the two parental lines, potentially indicating their significant roles in lodging. Subsequently, it was determined through qRT-PCR that four genes are likely to be the major genes controlling soybean lodging. CONCLUSIONS: This study's findings offer valuable insights into the genetic underpinnings of soybean lodging resistance traits. By comprehending the potential genetic factors associated with lodging, this research lays the groundwork for breeding high-yield soybeans with improved lodging resistance.

Bioinformatics Identification and Expression Analysis of Acetyl-CoA Carboxylase Reveal Its Role in Isoflavone Accumulation during Soybean Seed Development.

Isoflavones belong to the class of flavonoid compounds, which are important secondary metabolites that play a crucial role in plant development and defense. Acetyl-CoA carboxylase (ACCase) is a biotin-dependent enzyme that catalyzes the conversion of Acetyl-CoA into Malonyl-CoA in plants. It is a key enzyme in fatty acid synthesis and also catalyzes the production of various secondary metabolites. However, information on the ACC gene family in the soybean (Glycine max L. Merr.) genome and the specific members involved in isoflavone biosynthesis is still lacking. In this study, we identified 20 ACC family genes (GmACCs) from the soybean genome and further characterized their evolutionary relationships and expression patterns. Phylogenetic analysis showed that the GmACCs could be divided into five groups, and the gene structures within the same groups were highly conserved, indicating that they had similar functions. The GmACCs were randomly distributed across 12 chromosomes, and collinearity analysis suggested that many GmACCs originated from tandem and segmental duplications, with these genes being under purifying selection. In addition, gene expression pattern analysis indicated that there was functional divergence among GmACCs in different tissues. The GmACCs reached their peak expression levels during the early or middle stages of seed development. Based on the transcriptome and isoflavone content data, a weighted gene co-expression network was constructed, and three candidate genes (Glyma.06G105900, Glyma.13G363500, and Glyma.13G057400) that may positively regulate isoflavone content were identified. These results provide valuable information for the further functional characterization and application of GmACCs in isoflavone biosynthesis in soybean.

[Effects of different genotypes soybean and maize intercropping on soil phosphorus fractions and crop phosphorus uptake]. / ä¸åŒåŸºå› åž‹å¤§è±†ä¸ŽçŽ‰ç±³é—´ä½œå¯¹åœŸå£¤ç£·ç»„åˆ†ä¸Žä½œç‰©ç£·å¸æ”¶çš„å½±å“.

Reasonable soybean-maize intercropping mode can effectively promote soil phosphorus turnover and crop phosphorus absorption, and reduce phosphorus fertilizer input. To optimize phosphorus (P)-use efficiency in soybean/maize intercropping system, we intercropped two genotypes of soybean with maize to investigate the rhizosphere processes and mechanisms underlying soil biological P fractions and crop P uptake. The results showed that intercropping significantly depleted the rhizosphere soluble inorganic P (CaCl2-P) content in soybean genotype Yuechun 03-3, without impact on the P fractions in the rhizosphere of soybean Essex. Similarly, intercropping significantly increased biomass and P uptake of soybean genotype Yuechun 03-3 by 42.2% and 46.9%, respectively, compared to monoculture. However, it did not affect P uptake and biomass of soybean Essex and maize. Intercropping significantly increased both the total root length and the quantity of root exudates in Yuechun 03-3 by 19.7% and 138.1%, respectively. There was a significant positive correlation between P uptake and total root length in Yuechun 03-3, while a significant negative correlation between soluble inorganic P content and P uptake. In summary, intercropping of soybean and maize exhibited noticeable genotype differences in its impact on soil P fractions and crop P uptake. Intercropping has the potential to improve soybean P uptake and rhizosphere P turnover, mainly by increasing root length and root exudates of P-efficient genotype. The study would provide scientific evidence for optimizing the pairing of soybean and maize varieties in intercropping systems, thereby enhancing phosphorus utilization efficiency and reducing fertilizer inputs.

Diversity of soybean rhizobia in Northeast China and their application.

Biological nitrogen fixation is the main source of nitrogen in ecosystems. The diversity of soil rhizobia and their effects on soybeans need further research. In this study, we collected soybean rhizosphere samples from eight sites in the black soil soybean planting area in Northeast China. A total of 94 strains of bacteria were isolated and identified using the 16S rRNA and symbiotic genes (nodC, nifH) analysis, of which 70 strains were identified as rhizobia belonging to the genus Bradyrhizobium. To further validate the application effects of rhizobia, we selec-ted seven representative indigenous rhizobia based on the results of phylogenetic analysis, and conducted laboratory experiments to determine their nodulation and the impacts on soybeans. The results showed that, compared to the control without rhizobial inoculation, all the seven indigenous rhizobia exhibited good promoting and nodulation abilities. Among them, strains H7-L22 and H34-L6 performed the best, with the former significantly increasing plant height by 25.7% and the latter increasing root nodule dry weight by 20.9% to 67.1% compared to other indi-genous rhizobia treatments. We tested these two efficient rhizobia strains as soybean rhizobial inoculants in field experiments. The promoting effect of mixed rhizobial inoculants was significantly better than single ones. Compared to the control without inoculation, soybean yield increased by 8.4% with the strain H7-L22 treatment and by 17.9% with the mixed inoculant treatment. Additionally, there was a significant increase in the number of four-seed pods in soybeans. In conclusion, the application of rhizobial inoculants can significantly increase soybean yield, thereby reducing dependence on nitrogen fertilizer during soybean production, improving soil health, and promoting green development in agriculture in the black soil region of Northeast China.

[Characteristics of soybean climate potential productivity in frigid region and its response to climate change]. / å¯’åœ°å¤§è±†æ°”å€™ç”Ÿäº§æ½œåŠ›ç‰¹å¾åŠå ¶å¯¹æ°”å€™å˜åŒ–çš„å“åº”.

A comprehensive understanding of the evolution of soybean climate potential productivity and its response to climate change in Heilongjiang Province can offer reference and basis for further tapping soybean production potential and realizing stable and high yield of soybean in the frigid region. Based on meteorological data from 80 meteorological stations in Heilongjiang Province from 1961 to 2020, we estimated photosynthesis, light temperature, and climate potential productivity of soybean by the stepwise correction method, examined the spatiotemporal variations by spatial interpolation and statistical analysis methods, and analyzed the impact of changes in climate factors such as radiation, temperature, and precipitation on climate potential productivity. The results showed that during the study period, the average values of photosynthesis potential productivity (YQ), light-temperature potential productivity (YT), and climate potential productivity (YW) of soybean in Heilongjiang Province were 7533, 6444, and 3515 kg·hm-2, respectively. The temporal changes of those variables showed significant increasing trends, with increases of 125.9, 182.9, and 116.1 kg·hm-2·(10 a)-1, respectively. For the spatial distribution, YQ, YT, YW were characterized by high values in plains and lower in the mountains, and gradually decreased from southwest to northeast. Compared with that during 1961-1990, the high value zone of YW in period 1991-2020 expanded by 7.1%, and the low value zone decreased by 5.1%. YW showed a significant response to climate change. The potential temperature growth period was extended due to climate warming. The continuous increase in thermal resources, combined with relatively sufficient precipitation, effectively alleviated the negative impact of the decline in light resources on soybean production in Heilongjiang Province. The projected "warm and humid" climate would comprehensively boost climate potential productivity of soybean in Heilongjiang Province.

Characterization of Root Hair Curling and Nodule Development in Soybean-Rhizobia Symbiosis.

Soybean plants form symbiotic nitrogen-fixing nodules with specific rhizobia bacteria. The root hair is the initial infection site for the symbiotic process before the nodules. Since roots and nodules grow in soil and are hard to perceive, little knowledge is available on the process of soybean root hair deformation and nodule development over time. In this study, adaptive microrhizotrons were used to observe root hairs and to investigate detailed root hair deformation and nodule formation subjected to different rhizobia densities. The result showed that the root hair curling angle increased with the increase of rhizobia density. The largest curling angle reached 268° on the 8th day after inoculation. Root hairs were not always straight, even in the uninfected group with a relatively small angle (<45°). The nodule is an organ developed after root hair curling. It was inoculated from curling root hairs and swelled in the root axis on the 15th day after inoculation, with the color changing from light (15th day) to a little dark brown (35th day). There was an error between observing the diameter and the real diameter; thus, a diameter over 1 mm was converted to the real diameter according to the relationship between the perceived diameter and the real diameter. The diameter of the nodule reached 5 mm on the 45th day. Nodule number and curling number were strongly related to rhizobia density with a correlation coefficient of determination of 0.92 and 0.93, respectively. Thus, root hair curling development could be quantified, and nodule number could be estimated through derived formulation.

Glyphosate resistance and no fitness cost in backcross offspring of wild soybean and transgenic soybean with epsps gene.

BACKGROUND: The commercial utilization of genetically modified soybeans has yielded substantial economic advantages. Nevertheless, the genetic drift towards wild soybeans is one of the main ecological risks that needs to be addressed. Previous experiments demonstrated the absence of fitness cost or florescence overlap in hybrid offspring resulting from the crossbreeding of transgenic soybean GTS40-3-2 and Zhengzhou wild soybeans. In this study, hybrid progeny was systematically crossed with wild soybeans to establish a backcross progeny system. This system was employed to evaluate the ecological risk associated with the backcross progeny of transgenic and wild soybeans. RESULTS: The findings indicated that the offspring from the backcross exhibited glyphosate tolerance. Furthermore, the expression of foreign proteins in the backcross offspring was notably lower than in the transgenic soybean, and there was no significant difference when compared to the hybrid progeny. Parameters such as germination rate, aboveground biomass, pods per plant, full seeds per plant, and 100-grain weight exhibited no significant differences between the negative and positive lines of the backcross progenies, and no fitness cost was identified in comparison to wild soybeans. These results underscore the potential for foreign genes to propagate within other wild soybeans, which requires continuous attention. CONCLUSIONS: The widespread adoption of genetically modified soybeans has undeniably led to substantial economic gains. However, the research findings emphasize the critical importance of addressing the ecological risks posed by genetic drift towards wild soybeans. The backcross progeny system established in this study indicates that the potential for foreign gene dissemination to wild soybean populations warrants continued attention and mitigation strategies.