Journal of Shenyang Agricultural University

Function of Histone Methyltransferase SDG714 in Regulating Grain Shape

[Objective]Grain shape is one of the key agronomic traits that affect the yield and quality of rice(Oryza sativa), and dissecting its genetic mechanism is crucial for improving varieties. This study used a reverse genetics strategy to explore the function of rice histone methyltransferase SDG714 in grain development. [Methods]First, a phylogenetic tree of the SDG family was constructed using bioinformatics methods to analyze the phylogenetic relationship between SDG714 and SDG family proteins in Arabidopsis and rice. Next, CRISPR/Cas9 gene-editing technology was employed to modify the SDG714 gene within the genetic framework of the japonica rice variety ′Sasanishiki′. The key agronomic traits of the wild type and SDG714 mutants, such as grain length, grain width and 1 000 grain weight, were then compared and analyzed. Transcriptome sequencing was conducted to identify the downstream target genes of SDG714 that regulate grain shape, and RT-qPCR was used for verification. Finally, haplotype analysis was performed on the SDG714 coding region. [Results]Phylogenetic tree analysis and expression pattern analysis indicated that SDG714 might be involved in rice panicle development, and the H3 K9 me2 modification was reduced in SDG714 mutants. Investigation of geneedited plants showed that compared with the wild type, the grains of SDG714 mutants became slender, the 1 000 grain weight decreased significantly, while there were no significant changes in plant height and panicle number. The results of scanning electron microscopy revealed that the grain changes in SDG714 mutants were caused by the expansion of glume cells. The transcriptome sequencing results at the booting stage showed that among the significantly differential genes, there were 48 known genes involved in regulating grain shape, such as OsbZIP23, GS9, and DEP3. The haplotype analysis results demonstrated that compared with Hap I,Hap III had significantly increased grain length and grain length-width ratio, while significantly decreased grain width and 1 000 grain weight. [Conclusion]The rice methyltransferase SDG714 may regulate genes related to grain shape by affecting H3 K9 me2 methylation, thereby influencing rice grain size and 1 000 grain weight. These results reveal the key role of the SDG714 protein in the growth and development of rice and its grains, and provide a potential target for improving rice breeding.

Gene Mapping and Physiological Characteristics Analysis of Rice White Stripe Leaf Mutant ws20

[Objective]Leaf color mutants are valuable materials for studying chloroplast development and pigment biosynthesis in plants, having high application value. This study aims to investigate the physiological and molecular mechanisms of a white stripe leaf rice mutant in terms of chloroplast development, reactive oxygen species(ROS) scavenging, and yield-related traits. [Methods]Gene mapping was performed using the map-based cloning approach. Chloroplast ultrastructure was observed and ROS content was measured at the booting stage, while panicle traits were evaluated at the maturity stage. [Results]The white-striped leaf mutant ws20 was derived from an EMS-induced mutant library of the japonica cultivar‘SN9816'. Its phenotype was stably inherited and controlled by a single recessive gene. Compared with the wild type, the ws20 mutant displayed white-striped leaves with a 16.75% reduction in plant height, and no difference in the number of effective panicles. Fine mapping, candidate gene analysis, and gene sequencing revealed a C-to-T mutation at the 653 rd base of LOC＿Os06g14620, causing a glycine-to-valine substitution. Compared with SN9816,in ws20, chlorophyll and chlorophyll b contents decreased by 21.20% and 18.34%, respectively, along with significant reductions in chlorophyll precursors(e.g., ALA, PBG), leading to disrupted chlorophyll synthesis and abnormal chloroplasts. The antioxidant enzyme activities(SOD, CAT, APX, POD) declined, resulting in ROS accumulation. [Conclusion]This study demonstrates that the mutation in LOC＿Os06g14620 impairs chloroplast development and chlorophyll biosynthesis, weakens the antioxidant defense system, and leads to ROS accumulation, ultimately causing the white-striped leaf phenotype and growth inhibition in rice. These findings provide insights into the mechanisms of chloroplast development and ROS homeostasis in rice.

Analysis of Weed Community Composition and Succession Patterns in Maize Fields of Liaoning Province

[Objective]This study aimed to clarify the weed community structure and succession patterns in maize fields of Liaoning Province, with particular emphasis on evaluating the current damage status of common weeds such as Echinochloa crusgalli, Digitaria sanguinalis, Eriochloa villosa, and Commelina communis, so as to provide a basis for regional precise weed control. [Methods]From2021 to 2023, a systematic survey was conducted in maize fields across 14 cities in Liaoning Province. The “three-level survey method” combined with the “inverted W nine-point sampling method” was employed for the weed census. The composition and succession characteristics of the weed community were analyzed using indicators such as relative abundance. [Results]A total of 104 weed species belonging to 33 families and 78 genera were documented in the field surveys. Digitaria sanguinalis, Commelina communis, and Echinochloa crusgalli were identified as the most dominant weeds across the province, with relative abundance values of 38.61%, 34.97%, and 33.05%, respectively. Notably, D. sanguinalis dominated in all 14 surveyed cities, while Eriochloa villosa formed regionally high-density infestations in over half of the areas. Asteraceae and Poaceae emerged as the dominant families.Although annual weeds(64 species, 61.54%) and broadleaf weeds(85 species, 81.73%) predominated in species richness, Poaceae weeds dominated in terms of occurrence density. [Conclusion]The weed community in Liaoning's maize fields has undergone significant succession since 1986, with Echinochloa crusgalli, Digitaria sanguinalis, Eriochloa villosa, and Commelina communis emerging as the most damaging species currently. This study provides a data foundation for targeted weed control and prediction of succession trends in regional maize fields.

Effects of Straw Substitution of Partial Fertilizer on Organic Nitrogen Components of Soil in Facilities

[Objective]In facility vegetable production, excessive application of nitrogen fertilizers leads to a decrease in nitrogen fertilizer utilization rate. Utilizing organic material nitrogen as an alternative to chemical nitrogen fertilizers is crucial for achieving the goal of reducing nitrogen fertilizer application and increasing crop yields. This study aims to investigate the effects of replacing part of the chemical nitrogen fertilizer with nitrogen from crop residues on the organic nitrogen components and related enzyme activities in facility soil, and to further assess its contribution to the soil nitrogen supply potential and crop yield for the current season. [Methods]Five treatments were selected from the long-term location experiment of facility cucumbers: no fertilizer application(CK), single application of chemical fertilizer(100 CF), nitrogen from crop residues replacing 25%(25S), 50%(50S), and 100%(100S) of the chemical nitrogen fertilizer. The study explored the changes in the forms of soil organic nitrogen content, nitrogen transformationrelated enzyme activities, and their relationships with cucumber yield in each treatment. [Results]The straw replacement treatments significantly increased the contents of acid-soluble amino nitrogen, ammonium nitrogen, and amide sugar nitrogen in the soil, with the50S treatment showing the greatest increase(respectively, 31.50%, 8.12%, and 30.31%). The microbial biomass nitrogen increased with the increase in the substitution ratio. The activities of soil urease, protease, and nitrate reductase were significantly enhanced under the straw treatment, with the 50S treatment having the highest enzyme activity. The cucumber yield in the 50S treatment was significantly higher than that in the 100 CF treatment by 16.90%, while the 25S treatment also showed an increase, and the 100S treatment significantly decreased. The active organic nitrogen components were significantly positively correlated with cucumber yield,indicating that their supply has a direct contribution to the current season's cucumber yield. [Conclusion]Replacing part of the chemical nitrogen fertilizer with nitrogen from crop residues can optimize the composition of soil active nitrogen, increase cucumber yield, and 50% substitution of straw nitrogen for chemical nitrogen is the optimal replacement ratio for facility cucumber production.

Whole Genome Sequencing and Analysis of Pseudomonas syringae pv. actinidiae

[Objective]To enrich the genomic data of Pseudomonas syringae pv. actinidiae, the pathogen causing bacterial canker of Actinidia arguta, mine its pathogenic genes, and clarify the genomic differences among strains of different biovars of P. syringae pv.actinidiae.[Methods]The whole genome of pathogenic bacteria was sequenced and assembled with the Illumina and PacBio platforms,functional annotation of the coding genes was performed, comparative genome analysis was also conducted with different biovars of P.syringae pv. actinidiae. [Results]The chromosome size of Dg16 was 6 358 229 bp and the GC ratio was 58.67%. The two plasmids were 38 055 bp with 55.10% GC and 50 260 bp with 60.45% GC, respectively. A total of 5 374 coding genes were predicted, and 5366, 2 956, 3 958 and 4 305 genes were annotated in the Nr, KEGG, COG and GO databases, respectively. 1 240 genes were annotated in PHI database, 774 genes were annotated in carbohydrate active enzyme database, 450 secretion proteins, 72 secretion system proteins, 35 pairs of two-component system proteins, and 282 virulence genes were identified. The genome sizes and the number of coding genes of the four biovar strains were similar, and the genomes contained a large number of homologous genes, but there were many translocations, inversions and genomic variations. The number of unique gene families of Dg16, ICMP＿9853,MAFF212063 and Shaanxi＿M228 were 179, 184, 298 and 400, respectively, and the number of specific genes were 185, 234, 346 and448, respectively. The four biovar strains had 4 291 core genes and 6 354 pan genes. [Conclusion]The complete genome of P.syringae pv. actinidiae biovar 2, the pathogen causing bacterial canker of Actinidia arguta, was obtained. Potential pathogenic genes were mined, and the genetic relationships among strains of different biovars were clarified, providing a scientific basis for the subsequent study of the interaction mechanism between the pathogen and the host.

Screening of Low-Phosphorus Tolerance Indicators at Seedling Stage and Identification of Low-Phosphorus-tolerant Varieties of Soybean

[Objective]Study was carried out to study the low-phosphorus tolerance characteristics of different soybean varieties during the seedling stage, clarify the evaluation indicators for identifying low-phosphorus tolerance in soybean seedlings under lowphosphorus stress, and screen out low-phosphorus-tolerant varieties. [Method]Using 318 soybean varieties as the experimental materials, low-phosphorus stress treatment(LP, 0.05 mmol·L^-1KH₂ PO₄) and normal phosphorus treatment(NP, 0.5 mmol·L^-1KH₂ PO₄)were set up at the seedling stage. Nine indicators including plant height, main root length, above-ground dry weight, root dry weight,total root length, root surface area, root volume, root average diameter, and root tip number were measured. The low-phosphorus tolerance coefficients of each indicator were calculated. Variability analysis, correlation analysis, principal component analysis, and cluster analysis were conducted to analyze the characteristics of the indicators. The membership function method was combined to comprehensively evaluate the low-phosphorus-related indicators and low-phosphorus tolerance of different soybean varieties. [Result]There were extremely significant differences among the varieties for all 9 indicators. Except for the main root length and root tip number, there were significant differences in the other 7 indicators between the phosphorus treatments. The low-phosphorus tolerance coefficients of the 9 indicators could be simplified to 5 principal components. The cumulative contribution rate in the LP treatment reached 88.06%. A regression equation for evaluating the low-phosphorus tolerance characteristics of soybean seedlings was established: D =-0.454 + 0.221X_1+ 0.320X_2+ 0.247X_5+ 0.073X_8+ 0.058X₉, R²= 0.998(P < 0.01). The first-level evaluation indicators under the LP treatment were X₁(plant height), X₂(main root length), X₅(total root length), X₈(root average diameter), and X₉(root tip number). Among the 318 soybean materials, 61 materials belonged to low-phosphorus sensitive types, 102 materials belonged to low-phosphorus moderately sensitive types, 95 materials belonged to moderately tolerant types, and 60 materials belonged to tolerant types. [Conclusion]Five low-phosphorus tolerance indicators at soybean seedling stage, namely plant height, main root length,total root length, root average diameter, and root tip number were selected. 60 soybean varieties were identified as low-phosphorustolerant. The research results provide scientific methods for the identification and selection of soybean low-phosphorus-tolerant varieties, and also provide theoretical basis and material foundation for the exploration of low-phosphorus tolerance functional genes in soybeans and efficient utilization of phosphorus nutrition.

Spatiotemporal Evolution and Driving Factors of Rice Production Patterns in China in the New Century

[Objective]This study systematically investigates the spatiotemporal evolution characteristics and multidimensional driving mechanisms of rice production in China, aiming to provide decision-making support for optimizing the spatial pattern of rice production and ensuring national food security. [Methods]Based on panel data from 31 provinces(autonomous regions and municipalities) in China from 2000 to 2022, the study employs the concentration index, standard deviation ellipse, spatial autocorrelation analysis, and kernel density estimation to comprehensively reveal the spatiotemporal dynamics of rice production patterns. Furthermore, a Spatial Durbin Model(SDM) is applied to explore the comprehensive effects and spatial spillover mechanisms of multiple driving factors, including natural conditions, socioeconomic factors, input factors, and technological innovation. [Results]From 2000 to 2022, China's rice production exhibited a trend of “initial decline followed by fluctuating growth.” The spatial pattern showed a “southward contraction and northward expansion,” with the production gravity center shifting northeastward. Significant positive spatial autocorrelation was observed, characterized mainly by high-high and low-low clusters, though the degree of spatial agglomeration gradually weakened. Rice production displayed significant spatial spillover effects: natural conditions(sown area),socioeconomic factors(economic development level, non-agricultural employment opportunities, urbanization rate), input factors(effective irrigation area), and technological innovation(rice yield per unit area) were positively associated with rice production concentration, whereas input factors such as fertilizer input and rural labor force exhibited significant negative correlations. The effective irrigation area, non-agricultural employment opportunities, fertilizer input, and urbanization rate in neighboring provinces also significantly affected local rice production concentration. [Conclusion]To optimize the spatial pattern of rice production, attention should be given to spatial linkages among regions. Strengthening agricultural infrastructure, rationally controlling fertilizer application,and promoting coordinated urban-rural development are essential strategies to improve rice production efficiency and safeguard national food security.

Impact Mechanism of Urban-Rural Integration Development on New Quality Agricultural Productivity:An Empirical Test Based on Provincial Panel Data

[Objective]Further fostering and developing new quality agricultural productivity is of great significance for promoting the transformation and upgrading of modern agriculture and advancing the high-quality development of agriculture and rural areas.[Methods]Based on panel data of 30 provincial administrative regions in China from 2013 to 2022, this study employs the two-way fixed effects model, threshold effect model, and spatial econometric model to analyze the impact of urban-rural integration development on new quality agricultural productivity and its mechanism of action.[Results]The urban-rural integration development has a significantly positive impact on new quality agricultural productivity. The results indicate that with the improvement of urbanrural integration development level, its promoting effect on new quality agricultural productivity presents a nonlinear trend of diminishing marginal benefits; the promoting effect exhibits spatial heterogeneity, showing a significantly positive impact on new quality agricultural productivity in the eastern region and major grain-producing areas; the urban-rural integration development has a negative spatial spillover effect on new quality agricultural productivity, exerting an inhibitory effect on the development of new quality agricultural productivity in neighboring regions. [Conclusion]Accordingly, policy suggestions are proposed, including implementing precision policy guidance and regional coordination mechanisms, and strengthening investment in agricultural science and technology innovation.

Simulation Analysis and Optimization of Flow Field in Metering mechanism for Tomato Seedling Raising

[Objective]Seedling raising is a critical step in tomato production. However, the irregular shape and light weight of tomato seeds make high-performance seedling raising a difficulty in the industry. This study aims to identify the optimal structural and operational parameters of metering mechanism of a tomato seedling raising seeder through simulation and bench tests, with the expectation of providing key technical support for high tomato yields. [Methods]First, single-factor experiments were conducted to determine the influence of three factors—negative pressure air chamber diameter, fan blade thickness, and number of fan blades—on the negative pressure at the suction tube inlet. Then, an orthogonal experimental design was used to optimize the structural parameters of the metering mechanism of the seeder, and the optimal structural parameters combination was obtained. Finally, the optimized design was 3D-printed into a physical prototype and installed on a test bench for bench trials. These trials further verified the performance of the metering mechanism after structural optimization, and an orthogonal experiment was carried out to determine the optimal operational parameters.[Results]The simulation validation test showed that with 9 fan blades, a negative pressure chamber diameter of 66 mm, and a fan blade thickness of 2.1 mm, the negative pressure at the suction tube inlet reached 143.32 Pa. The error between the response surface methodology prediction and the CFD numerical simulation was 2.19%. Bench validation test results indicated that the negative pressure at the orifice inlet was 137.79 Pa, at a fan speed of 1 500 r·min^-1, the error is 4.01% between the bench test results and the numerical simulation results for orifice negative pressure. [Conclusion]The operational parameter optimization experiment demonstrated that the optimal parameter combination is a roller speed of 8.5 r · min^-1and a fan speed of2 400 r·min^-1. Under these conditions, the qualified seeding rate, multiple suction rate, and missed seeding rate are 93.92%, 5.66%,and 0.42%, respectively, meeting the requirements for tomato seedling raising seeding.

Soil-sickness Problem in the sustainable Development for the Protected Production of Vegetables

As the development of specialized production of vegetable crops, soil sickness has been a problem for the sustainable production of vegetable crops. Soil sickness is mainly caused by soil--borne pests, disorder of soil physical and chemical properties, and autotoxicity. The present paper discussed possible role of cropping system, biological control and grafting in the soil--borne pest control, role of organic fertilizer, desalting and reasonable fertilization in soil restoration, and the alleviation of autotoxicity by grafting, adsorption with charcoal and degradation by microbes.

Current Situation and Prospects of Green House Industry Development in China

This paper summarized comprehensively the history, current development of the green house industry and its researches. The historic significance, problems, and prospects were also analyzed. The summary was expected to provide references for determining the historic position and future developmental direction of green house industry.

Effect of Lodging Resistance on Yield and Its Relationship with Stalk Physical Characteristics

Stalk physical characteristics and tilt angle of matured plant of eighteen populations from six cultivars wereinvestigated under three conditions. The relationships between lodging resistance and yielding were also studied. TheresultS indicated that: the intensity of lodging of rice population could be grouped into three categories-lodging, slantand erect types according to the tilt angle of matured plant. Lodging resistance is significantly negatively correlatedwith the length of the first internode, and significantly positively correlated with the area of the basal stalk and withthe thickness of the hasal stalk. Difference among varieties and lodging resiStance was also found. Nitrogenapplication also had an obvious effect upon population lodging of rice. But if only yielding was considered, the highyield populations were given usually in the medium fertilization treatment. Therefore, rice resistance to the lodgingcould be improved by means of shortening length between the first and the second internode, strongtheningthe hardnes of the basal stalk, lowering the position of panicle, and elonging panicle or the neck-panicle internode.So the contradiction between lodging resiStance and plant height could be settled at a level of higher yielding.

Comparison of A New Model of Light Response of Photosynthesis with Traditional Models

Photosynthetic rates increase gradually with light intensity in the traditional models of light response curve of photosynthesis,i.e.rectangular hyperbolic model and nonrectangular hyperbolic model.So the maximum net photosynthetic rates calculated by nonrectangular hyperbolic model and rectangular hyperbolic model were far more than the measured data,and the saturation light point was not obtained.A new model of light-response of leaf net photosynthesis was proposed in this paper.Some properties of the new model of light-response of leaf net photosynthesis were discussed in detail.Results showed that the data of light-response of leaf photosynthesis of winter wheat under different environmental conditions were modeled by three models.The results fitted by nonrectangular hyperbolic model,rectangular hyperbolic model and the new model were compared.In addition,the measured data of light response of photosynthesis under different temperatures and CO2 concentrations could be dealt with,and the main parameters of photosynthesis,i.e.the maximum photosynthetic rates,saturation light point,light compensation point and the rate of dark expiration could be calculated without any hypotheses.The response data of leaf photosynthetic rate to irradiance under low irradiance and photo inhibition could be fitted by the new model.The measured data of light response of photosynthesis under different temperatures,CO2 concentrations and light intensity,including at low photon fluxes and photo inhibition could be dealt with.The fitted results were tallied with very well the measured data.So the new model has generality.

Current Situation of Remediating Techniques of Petroleum Contaminated Soil and Its Prospects

Current situations and damage of petroleum contaminated soils were summarized. Several main methods and techniques of remediating petroleum contaminated soil, application as well as advantages and disadvantages of the techniques were introduced in the paper. It points that traditional methods and techniques should combined with the bioremediation in the process cleaning the pollution, which will play the advantages of respective techniques. In the same time, the economic benefit, social benefit and environmental benefit should be considered together in treating petroleum contaminated soils.

A COMPARISON OF METHODS OF MEASUREMENT OF CHLOROPHYL IN PLANTS

Current Situation and Prospects of Green House Industry Development in China

This paper summarized comprehensively the history, current development of the green house industry and its researches. The historic significance, problems, and prospects were also analyzed. The summary was expected to provide references for determining the historic position and future developmental direction of green house industry.

Determination of Blueberry Anthocyanins through pH Differential Method

For determinieg the contents of blueberry anthocyanins more exactly,the blueberry pigments were extracted by acidic alcohol and were identified anthocyanins by UV-VIS spectra and chemical methods.The blueberry anthocyanins were quantitatively analyzed through pH differential method.The results indicated that the content of blueberry anthocyanins was 313.24mg.100g-1 and the relative standard deviation was 1.39%.The influence on measuring results by impurity in the solution was eliminated by pH differential method.

Status and Developing Prospects of Biopesticide Research and Application

Biopesticides have many advantages over the traditional chemical pesticides,being safe to human,livestock and nontarget organisms,having wonderful environmental compatibility,stable controlling effects and benefit to protect the biodiversity,and having many resources etc.Status of research and application of biopesticides were reviewed in this paper.The authors pointed out the major problems in the research and application of biopesticides.The developing prospects of biopesticides were discussed and some advices were given for biopesticide development in future.

Current Situation of Remediating Techniques of Petroleum Contaminated Soil and Its Prospects

Current situations and damage of petroleum contaminated soils were summarized. Several main methods and techniques of remediating petroleum contaminated soil, application as well as advantages and disadvantages of the techniques were introduced in the paper. It points that traditional methods and techniques should combined with the bioremediation in the process cleaning the pollution, which will play the advantages of respective techniques. In the same time, the economic benefit, social benefit and environmental benefit should be considered together in treating petroleum contaminated soils.