Journal of Shenyang Agricultural University

Effect of Abscisic Acid on Accumulation of β-carotene in Oriental Melon Fruit

[Objective]Study was carried out to clarify the effect of abscisic acid(ABA) on the accumulation of β-carotene in oriental melon fruit, and to reveal its mechanism in fruit ripening and nutritional quality, so as to rationally use ABA to promote the accumulation of β-carotene in fruits, improve the flavor quality, nutritional value and economic benefits of oriental melons, and provide a theoretical basis for cultivating high-quality oriental melons that meet people's needs. [Method]The orange flesh variety HDB was used as the test material, the fruit was sprayed with 100 mg·L^-1ABA and its inhibitor Nordihydroguaiaretic acid(NDGA) on20 days after flowering(when the flesh color was not transformed). Samples were taken on 0,1,3,5,7,9,11,13,15 days after treatment to determine the soluble solid content(SSC), flesh color, ethylene production, endogenous ABA content, β-carotene content and gene expression of synthesis pathway in the melon fruit.[Results]The ABA treatment could advance the accumulation of soluble solids in melon fruit, but does not affect the final SSC. It can accelerate the decline of the brightness of melon flesh and promote its early color change; it can increase ethylene production and endogenous ABA content in melon fruit; and it could promote the early accumulation of β-carotene in melon fruit, without affecting the final content. And it could significantly enhance the relative expression of synthesis genes(CmPSY and CmLCYB) related to the carotenoid metabolic pathway in melon fruit. Conversely, the NDGA treatment inhibited the synthesis of endogenous ABA and accumulation of β-carotene and significantly reduced the content ofβ-carotene in fruit. [Conclusion]Exogenous ABA treatment can promote the synthesis of ethylene and endogenous ABA in melon fruits, promote the ripening of melon fruits, improve the expression of β-carotene synthesis genes in melon fruit, and promote the synthesis and accumulation of β-carotene in melon fruit. The results of the experiment can provide a theoretical basis for using ABA to increase the β-carotene content of oriental melon fruit.

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 88.07%. 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.

Genetic Relationship Analysis of “Songgeng” Series Elite Rice Varieties and Their Parents Based on Whole Genome Re-sequence

[Objective]The analysis of genetic diversity of elite varieties can provide a deeper understanding of the breeding process and genetic differences among varieties, and provide more valuable diversity data and breeding strategy support for guiding molecular breeding practices. [Methods]This study analyzed the elite rice varieties of the "Songgeng" series and their associated elite parents or derived varieties in the first accumulated temperature zone of Heilongjiang Province through whole genome resequencing technology. A phylogenetic tree was constructed using single nucleotide diversity data and genetic distance was calculated. [Results]A total of 2 908684 SNP loci and 685 321 InDel loci were obtained through population sequencing. The analysis of SNP differences among varieties showed that there were more than 600 000 SNP differences between Wuyoudao A and Dongnong V4, Songgeng 13, Jigeng 88 and Wuyoudao 4. However, there were only 685 321 SNPs between Songgeng 6 and Wuyoudao 3. The phylogenetic tree show that Wuyoudao 4, Songgeng 22 are grouped together, while Wuyoudao 1, Song 98-131, Songgeng 8, Songgeng 9, and Songgeng 16 are grouped together and have close genetic relationships. The genetic distance analysis shows that the genetic distance between Wuyou A and other varieties is relatively long, with a largest genetic distance of 0.219 1 from Songgeng 13. The genetic distance between Wuyoudao 3 and Songgeng 6 is the closest, only 0.002 6. [Conclusion]Differential analysis or cluster analysis can be used to assess the relationship or genetic distance between individuals. In the formulation of breeding plans, priority should be given to crossing parents with greater genetic distance. This approach helps generate segregating progeny with greater diversity, thereby increasing the probability of selecting superior new varieties.

Identification and Biological Characteristics of Pathogens Causing Tobacco Root Rot Disease in Liaoning Province

[Objective]In recent years, the newly emerging tobacco root rot disease in Kuandian tobacco-growing area of Dandong City,Liaoning Province, can cause stunting, yellowing of mature plants and root rot, which seriously threatens local tobacco leaf production.This study aims to identify the species of pathogenic fungi and their biological characteristics, to provide a basis for precise prevention and control. [Methods]Pathogens were isolated and purified from the root of diseased tobacco plants in Kuandian County, Dandong City, Liaoning Province by tissue isolation method, and their pathogenicity was verified using Koch's postulates. The species of pathogenic fungi were identified based on morphological observation and multi-gene(ITS, TEF-1α, RPB2) phylogenetic analysis.Meanwhile, the optimal culture conditions(temperature, pH, light) for the pathogens were studied, and the infection ability of the strains on crops such as pepper, tomato, eggplant and pumpkin was determined by root irrigation inoculation with spore suspension.[Results]A total of 72 fungal strains was isolated and purified from the disease-affected area, and their cultural characteristics were basically consistent. Among them, strains GF11 and GF12 showed the strongest pathogenicity. Through morphological and molecular biological identification, they were identified as Fusarium oxysporum and F. solani respectively. The biological characteristics showed that the optimal growth temperature for the mycelia of both fungi was 28℃ under the condition of total darkness. The optimal pH values for GF11 and GF12 were 5 and 6, respectively, and the lethal temperatures for their conidia were 60 ℃ and 65 ℃,respectively. Both pathogens could cause root rot in tomato and pepper. In addition, GF11 could induce typical root rot symptoms in corn and pumpkin, and GF12 could cause the same symptoms in eggplant. [Conclusion]This study is the first to confirm that the pathogens causing tobacco root rot in Liaoning are F. oxysporum and F. solani. Their biological characteristics and host range are also clarified, which provides a scientific basis for optimizing field management, mechanism study and targeted control.

Effects of Straw Pelletization on Spatial Microenvironments and CAZy Functional Gene Profiles in Black Soils

[Objective]Straw return is an important management practice for improving soil organic carbon levels and enhancing the structure of the plough layer in black soil regions. However, conventional straw return methods generally suffer from slow decomposition rates and low utilization efficiency. Straw pelletized return aims to accelerate straw decomposition by altering its physical form. In this study, four typical black soil regions in eastern Inner Mongolia were selected as research sites. [Method]Four treatments were established: straw return(JG), straw return with microbial inoculant(JJ), straw pellet return(KL), and straw pellet return with microbial inoculant(KJ). Straw decomposition rate, soil physicochemical properties, enzyme activities, and the spatial variation of CAZy functional genes based on metagenomic analysis were investigated. Random forest and redundancy analysis were further applied to reveal the driving mechanisms.[Results]The results showed that straw decomposition rates exhibited significant spatial variation, and spatial effects were stronger than treatment effects. Soil physicochemical properties and enzyme activities were primarily clustered by spatial location, indicating that environmental background conditions played a dominant role in shaping soil microenvironments. Microbial CAZy functional genes differed significantly among regions, with glycoside hydrolases(GH) and glycosyltransferases(GT) being the dominant groups, while key lignocellulose-degrading families showed region-specific enrichment patterns. Driving factor analysis indicated that soil organic carbon, sucrase activity, and soil physicochemical properties were the key factors shaping CAZy functional structures and straw decomposition processes, whereas the direct contribution of individual functional genes was relatively limited.In conclusion, the straw decomposition process is mainly regulated by spatial environmental background,while microbial functional genes undergo adaptive adjustments under given physicochemical conditions.[Conclusion]These findings provide a theoretical basis for the application and optimization of straw return technologies in black soil regions.

Tobacco Shreds Conveying Simulation and Pipeline Optimization Based on Discrete Element Method

[Objective]To improve the accuracy and reliability of the discrete element method in optimizing the design of tobacco shred conveying elbows, an X-Y-Z three-dimensional irregular breakage model was established. Based on this, a gas-solid coupling method(CFD-DEM) was employed to optimize the elbow structure design. [Methods]Taking Hongshuangxi(Hard) tobacco shreds from a cigarette factory as the research object, the key parameters for the breakage model were measured through methods such as the heavyball drop test. With the pipe bending angle, bending radius, and inlet-outlet length ratio as critical experimental factors, and the pipeline wear condition and the remaining Bond key ratio of tobacco shred particles as experimental indicators, the influence of each factor on tobacco shred conveying costs was analyzed. [Results]The total pipeline wear decreased with increases in both the bending angle and bending radius. The degree of pipeline wear for different inlet-outlet length ratios followed the order: 1∶1.5 < 1∶1 < 1.5∶1.The remaining Bond key ratio of tobacco shred particles increased with the increase of the bending angle; it first decreased and then increased with the increase of the bending radius; and the degree of tobacco shred breakage for different inlet-outlet length ratios followed the order: 1∶1.5 < 1∶1 < 1.5∶1. The orthogonal experiments revealed that the order of the factors affecting tobacco shred quality were: the inlet-outlet length ratio, bending radius, and bending angle. The optimal factor combination for the pipeline was a bending angle of 150 °, a bending radius of 1 500 mm, and an inlet-outlet length ratio of 1∶1.5. Under this condition, the simulated breakage rate for 10 g of tobacco shred particles during conveying was 1.505%. The verification test of the breakage rate of this optimal combination yielded an actual breakage rate of 1.333%, with a relative error of 0.172%. Compared with the actual breakage rate under general operating conditions for elbow conveying, it was reduced by 3.074% approximately, effectively lowering the cigarette conveying costs. [Conclusion]The optimized elbow structure reduces the breakage of tobacco shreds after pneumatic conveying. The research findings can provide a theoretical basis for the rational layout of pipelines and the optimized design of elbows.

Response of Primary Root Elongation Induced by Nitrogen Deficiency to Regulation Involving OsDGL1-Mediated Cell Wall Rhamnose Metabolism

[Objective]Under nitrogen-deficient conditions， plants can enhance nitrogen uptake by promoting primary root growth; yet the molecular mechanisms underlying this adaptive response remain poorly understood. This study aimed to elucidate the intrinsic regulatory mechanisms of root morphological adaptation in rice in response to nitrogen deficiency， with a specific focus on clarifying the relationship between primary root growth regulation and nitrogen uptake efficiency. [Methods]Wild-type rice and the Osdgl1 mutant were used as experimental materials. Plants were subjected to either normal nitrogen supply or nitrogen-deficient conditions. Primary root growth phenotypes were systematically observed and measured. Concurrently， changes in the content of root cell wall components—including rhamnose， xylose， and cellulose， were analyzed. [Results]Nitrogen-deficient treatment significantly promoted primary root elongation of rice and partially restored the short-root phenotype of the Osdgl1 mutant. Genetic evidence indicated that OsDGL1 plays a crucial role in nitrogen deficiency-induced root growth. Further analysis revealed that changes in root length were primarily correlated with the content of rhamnose and xylose in the cell wall， but not with cellulose content. These findings suggest that rhamnose biosynthesis may serve an important function in this adaptive process. [Conclusion]OsDGL1 likely mediates the growth response of rice primary roots under nitrogen-deficient conditions by regulating the rhamnose biosynthesis pathway. This study provides novel insights and identifies future research directions for unraveling the molecular mechanisms through which nitrogen deficiency modulates root development in rice.

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.

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.