Zeaxanthin is a carotenoid pigment, which was named from maize where it was first extracted. Because it couldn’t be synthesized by human, and it was obtained only from daily dietary food, and could not only protect eyes, but also played an important role in the prevention of aged-related macular degeneration (AMD, the leading cause of blindness), cataract, cardiovascular diseases, cancer and so on, people paid more attention to zeaxanthin in crops. In this study, the properties and source of zeaxanthin, its physiological functions and its biosynthesis pathway were summarized according to new progress. Moreover, its extraction, measurement methods and application in food industry were also reviewed. In addition, studies on zeaxanthin-rich crops were discussed.

【Objective】The objective of this study is to screen Trichoderma strains which have inhibitory effect on the Pythium spp. causing maize stalk rot, and to clarify their taxonomic status, control efficacy and antifungal mechanism. This study will provide important resources for the research and development of biocontrol agent against Pythium stalk rot.【Method】For the antagonistic strains screening, the inhibitory effect of Tichoderma strains on P. inflatum, P. arrhenomanes and P. aristosporum was tested by measuring the mycelia growth. The taxonomic status of Tr21 was determined by morphological and molecular characteristics. The effect of Tr21 on the mycelia morphology of Pythium spp. was observed in the laboratory. In order to analyze the effect of Tr21 fermentation broth on the membrane permeability of Pythium spp., propyridine bromide (PI) dye solution was used to stain, and the absorbance values of protein and nucleic acid in mycelia supernatant at different treatment times were detected. The effect of Tr21 fermentation broth on germination characteristics of maize seeds was tested by seed soaking with different concentrations of fermentation broth. The control efficacy of Tr21 on stalk rot was confirmed through greenhouse pot and field inoculation experiments.【Result】From the 109 strains of Trichoderma spp., seven strains were screened with antagonistic activity against P. inflatum, P. arrhenomanes and P. aristosporum, and the inhibition rate was above 60%. The inhibition rate of Tr21 to three Pythium species reached 100%, the inhibition rate of 5×, 10× and 20× diluent to three Pythium species reached 100%, and the inhibition rate of 50× diluent to three Pythium species was also more than 55.56%. Tr21 strain was identified by morphological and molecular biology as T. afroharzianum. The results of microscopic observation showed that the fermentation broth of Tr21 could cause mycelial malformations, such as rough mycelia, increased mycelial branching, shortened nodes, and overflow of mycelia contents. The result of PI fluorescence stain showed that the cell membrane of three Pythium species was damaged by Tr21 fermentation broth, and the PI dye was more likely to penetrate the damaged cell membrane into the mycelium and stain the mycelia red. The results of nucleic acid and protein leakage showed that the absorbance values of the mycelia treated by the fermentation broth changed greatly. After treatment for 5 h, the OD₂₆₀ increased by 0.08 and OD₂₈₀ increased by 0.10, 0.11 and 0.10, respectively, indicating that the membrane of the mycelia was damaged, leading to the overflow of mycelia contents. The different concentrations of Tr21 fermentation broth had no effect on the germination characteristics of maize seeds, and the 20× diluent had the best effect on germination and growth of seeds. The results of pot experiment showed that 5× diluted fermentation broth of Tr21 had the best control efficacy on Pythium stalk rot caused by three Pythium species, which was 60.67%, 63.15% and 59.66%, respectively. The control efficacy on Pythium stalk rot of 5× diluent was the highest, reaching 82.25%, with a mass ratio of 1﹕100 (5× diluent to seed).【Conclusion】An effective T. afroharzianum strain Tr21 was obtained for preventing and controlling of maize Pythium stalk rot. The fermentation broth of Tr21 can lead to mycelia malformation, breakage, cell membrane damage and contents leakage, etc. In conclusion, the T. afroharzianum strain Tr21 is a promising biocontrol microbial.

Maize is one of the most important grain crops in the world. Improving the kernel quality of maize is a highly concerned problem in the field of maize breeding worldwide. The traditional and conventional breeding methods have the limitations of long breeding time and low transformation rate, so the most economical and effective way to solve this problem is to use molecular marker assisted selection breeding. In order to provide reference for molecular design and breeding of maize quality traits in the future, this study summarized relevant research progress of QTL mapping, molecular marker assisted improvement, candidate gene cloning and transgenic technology application of maize kernel quality traits at home and abroad. Based on the review, the study points out that the utilization of high-quality gene resources in maize is not sufficient, and the application of existing molecular marker technology in maize breeding is not extensive enough. In the future, breeding methods and quality identification techniques should be improved to shorten the breeding cycle of maize.

In field production, new maize varieties with U.S. germplasm such as ‘Xianyu 335’ are weak in resistance to dense planting, lodging, Southern Corn Rust, leaf blight, and high temperature and heat. To solve these problems by means of plant breeding, we use maize new variety ‘Yufeng 303’ as the test material to study its performances, including yield performance, drought tolerance, high temperature and heat tolerance, dense planting resistance, and grain quality at production trials, at national trials (Huang-huai-hai Summer Maize Area, Eastern of North China Middle and Late Maturity Spring Maize Area, and Northwest Spring Maize Area) and provincial trials. The results show that ‘Yufeng 303’ not only possesses the desirable traits of new maize varieties with U. S. germplasm, but also has traits of high tolerances to drought, high temperature and heat, lodging, and Southern Corn Rust, achieving and substantially surpassing our original breeding goal. Based on these results, several issues for future breeding, including the general technical route of germplasm expansion, improvement and innovation, the avoidance of genetic vulnerability risk and others related to commercial breeding, are discussed. The study emphasizes the importance of breeding the traits of high temperature tolerance and drought tolerance, especially the importance of breeding new varieties with wide stress adaptability by constantly uplifting the positive super normal expression of genotype environment interaction.

To have a comprehensive and in-depth understanding of the current situation and development trend of researches on maize planting density and yield at home and abroad, 5150 pieces of literature on maize planting density and yield collected from the CNKI database and Web of Science Core Collection database from 2000 to 2022 were taken as samples for visual analysis based on CiteSpace software. The results showed that the United States ranked first in the total research volume in this field, followed by China, far beyond other countries. In recent years, China had overtaken the United States in the number of research papers in this field, and kept more than 100 articles published every year. Agronomy Journal had the largest number of publications, with a total of 230 papers, and had the largest influence in academic circles. Chinese scholar Liu Peng published the most papers, made the greatest contribution to the research progress in this field, and cooperated closely with other authors. The research institutions were mainly universities, mostly in northern China, and the cooperation among regional institutions needed to be strengthened. In this field, special corn such as fresh food and silage corn, water and nitrogen utilization efficiency, sustainable agriculture, mechanized management, soil properties, yield loss, mathematical model, straw utilization, and so on are the hot research issues in recent years.

In view of the shortage of water and heat resources in different ecological areas, and the frequent occurrence of wind disaster, lodging, low yield, poor quality and other problems in maize production, a new maize variety ‘MC278’ was bred by taking ‘Jing X005’ as female parent and ‘Jing 27’ as male parent. The inoculation tests of the variety in Jilin, Hebei and other places showed that it had strong resistance to small spot disease, Curvularia, dwarf mosaic, silk smut and stem rot, and was easy to infect large leaf spot, and it was moderately resistant to corn borer in Jilin. In the regional trials in Beijing, Inner Mongolia and other regions in different years, the kernel yield of ‘MC278’ was significantly higher than that of ‘Zhengdan 958’ (CK), the highest yield was 16166 kg/hm², and the average yield was increased by 8.3%. The content of crude protein, crude starch and lysine of ‘MC278’ were significantly higher than those of ‘Zhengdan 958’. In 2019, the production in Hebei, Shanxi, Inner Mongolia and other regions showed that the yield of ‘MC278’ was all more than 12804 kg/hm², and the maximum yield was 14283 kg/hm². ‘MC278’ was equipped with field management measures and harvest techniques, such as suitable sowing date, density and water and fertilizer management, and prevention and control measures of diseases and insect pests. The variety passed the national examination and approval in 2019 (National Approved Maize Variety No.20190030), and its planting area now includes 15 provincial regions, such as Anhui, Shanxi, Shandong and etc.

Research on forage maize can effectively promote the development of animal husbandry. In order to accelerate the progress of forage maize, this paper reviewed the regulation mechanism and breeding process of quality protein maize. Meanwhile, the characteristics and breeding process of high protein silage maize were introduced in detail. The problems existing in the development of quality protein maize and high protein silage maize were pointed out, and some relevant suggestions were put forward in order to promote the structural reform of maize from food crop to feed crops in China.

【Objective】 Mining the key drought-resistant genes of maize, revealing its drought-resistant molecular mechanism, and providing genetic resources and theoretical guidance for the cultivation of new drought-resistant maize varieties.【Method】Transcriptome data combined with weighted gene co-expression network (WGCNA) and screening methods for physiological and biochemical indicators of drought resistance were used to identify ZmPAL genes associated with drought resistance and rewatering. Genome-wide analysis of the genes encoding PAL was performed using bioinformatics methods. Quantitative real-time fluorescence PCR (qRT-PCR) was used to detect the expression of ZmPAL genes under drought treatment conditions, as well as the expression characteristics of ZmPAL5 among different inbred lines and the expression patterns in different tissues. Finally, genetic transformation was used to analyze the drought resistance function of ZmPAL5 in maize, and the deletion-type Arabidopsis mutant was analyzed for drought resistance with the help of CRISPR/Cas9 technology for the PAL5 homologous gene.【Result】Nineteen maize ZmPAL genes were identified, six of which were clustered on chromosome 5 and encoded proteins that were mostly hydrophilic acidic proteins and relatively evolutionarily conserved in the PAL family of genes. The promoter region of ZmPAL genes contained a large number of cis-acting elements associated with hormonal and abiotic stress responses. Six core genes were identified, four of which were significantly up-regulated for expression after drought treatment. In particular, ZmPAL5 showed an 8.57-fold increase in expression after drought stress. The expression level of ZmPAL5 was found to be significantly higher in the drought-resistant inbred line Zheng 8713 than in the drought-sensitive inbred line B73 under both drought stress and rewatering treatments. Meanwhile, ZmPAL5, a constitutively expressed gene, showed a high level of expression in young stems. Overexpressed ZmPAL5 maize grew well under drought stress, and its relative water content, lignin, chlorophyll, soluble protein, proline content, and activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase were 1.52, 1.49, 1.47, 1.43, 1.44, 1.41, 1.53, 1.41, and 1.35 times, but the malondialdehyde content was 0.65 times that of the wild type. The PAL5-deficient Arabidopsis mutant was sensitive to drought. Under drought stress, its physiological and biochemical indexes showed the opposite trend to those of overexpression of ZmPAL5 maize. 【Conclusion】 Six core genes (ZmPAL3, ZmPAL5, ZmPAL6, ZmPAL8, ZmPAL11, and ZmPAL13) were screened in response to drought stress, in which the expression of ZmPAL5 was positively correlated with drought resistance. ZmPAL5 positively regulated the drought resistance and resilience of the plant by influencing the content of osmotically regulated substances and antioxidant enzyme activities.

In order to promote the application of molecular marker-assisted selection in maize breeding, the research progress of QTL of kernel yield of maize and its components’ traits in recent 30 years was summed up. The results showed that there were 5-9 QTLs for kernel yield, and they were mainly distributed on chromosome 1, 2, 5, 6, 7, 8 and 9. There were 3-6 QTLs for the kernel row number, kernel number per row and 100-kernel weight, and they were mainly distributed on chromosome 1, 2, 3, 4, 5, 6, 7 and 8. These QTLs were distributed in clusters on several main chromosomes and formed QTL enrichment regions, and they could explain about 25% of the phenotypic variation in traits. QTLs of most traits mainly manifested as additive, dominant, partial dominant or superdominant effects, and QTLs of some traits showed genetic × environment interaction. It indicated that QTLs of kernel yield and its components’ traits had common chromosomal carriers, the breeding selection should be carried out in multiple environments and with large number of samples, and those QTLs that could be expressed stably in different environments were more suitable for breeding selection. The QTL study on ear number per plant, plant traits and stress resistance should be strengthened.

【Objective】 Maize ear rot caused by Fusarium verticillioides is one of the most serious diseases in maize producing areas in China. The objective of this study is to understand the differences in gene expression during the plant-pathogen interaction at different stages, and to provide a basis for pathogenic mechanism of the pathogen infection and resistance mechanism of maize. 【Method】 Illumina platform was used to sequence the transcriptome of maize kernels infected with F. verticillioides at 0, 4, 12, and 72 h. The differentially expressed genes (DEGs) of maize and F. verticillioides were screened with |log₂FC|≥1, P-adjust<0.05 as threshold and clean reads were compared with genome of maize and F. verticillioides, separately. Functional annotation and enrichment analysis of DEGs were carried out by using GO and KEGG databases. Goatools software was used to analyze the expression changes of genes related to plant-pathogen interaction, MAPK signaling pathway and plant hormone signal transduction pathway. Sequencing results were verified by quantitative real-time PCR (qRT-PCR). 【Result】 A total of 140, 400 and 1 945 DEGs were up-regulated and 9, 302, and 1 784 DEGs were down-regulated in F. verticillioides after 4, 12 and 72 h interaction, respectively. A total of 293, 692, and 1 426 DEGs were up-regulated and 320, 482, and 153 DEGs were down-regulated in maize after 4, 12 and 72 h interaction, respectively. GO and KEGG enrichment analysis of DEGs showed that F. verticillioides grew in intercellular space at the early stage of pathogen infection. The DEGs were enriched in RNA biosynthesis, cell wall structural component, fatty acid biosynthesis, protein metabolism, carbohydrate metabolism, biological process, and metabolic process. Reactive oxygen species (ROS) was triggered in maize at the early stage of infection. The DEGs were enriched in response to ROS, hydrogen peroxide, chitinase activity, monooxygenase activity, lignin metabolism. At the later stage of infection, F. verticillioides colonized and expanded in maize, and the DEGs were enriched in carbohydrate and cell wall polysaccharide catabolic process, transmembrane transport and oxidoreductase activity. Maize responded to pathogen infection through phenylpropanoid, lignin, flavonoid biosynthesis, MAPK signaling pathway, plant-pathogen interaction and plant hormone signal transduction. Six DEGs of maize and six DEGs of F. verticillioides were randomly selected for qRT-PCR. The results were consistent with those of transcriptome sequencing, which confirmed the accuracy of RNA-seq. 【Conclusion】 At the early stage of infection, F. verticillioides grew in the intercellular space, triggering ROS outbreak in maize and the expression of related pathway differential genes. At the middle and late stages of infection, the pathogen further colonized and expanded in maize with starch as nutrient. Maize responded to the infection of F. verticillioides through biosynthesis of phenylpropanoid, lignin and chitinase. Meanwhile, plant-pathogen interaction, MAPK signaling pathway, and plant hormone signal transduction were involved in the resistance to the infection of F. verticillioides.

To study the effects of maize seed dressing with chlorantraniliprole on seed germination, seedling growth and physiological and biochemical indexes, plate experiments in incubator and indoor pot experiments were conducted to study the seed germination, seedling growth (plant height, root length, root shoot ratio, etc.), physiological and biochemical indexes (protective enzyme, root activity and chlorophyll content, etc.) of maize by seed dressing with different dosage (0.5, 1, 2, 3, 4 g/kg) ofhlorantraniliprole. The results showed that chlorantraniliprole at 0.5- 3 g/kg significantly increased the germination potential, germination rate, germination index, vigor index of maize and increment in seedling stage, induced the activity of CAT, POD, SOD, PAL and PPO in maize seedling leaves, and increased root activity, chlorophyll content, sugar content and soluble protein content. Chlorantraniliprole inhibited the growth of maize after treated with 4 mg/kg, but the indicators were still higher than that of the control. In conclusion, chlorantraniliprole at suitable dosage could significantly promote seed germination and seedling growth of maize.

‘Yongyou 988’ is a new maize variety bred by Hebi Academy of Agricultural Sciences with T1932 from European flint line as the female parent and ‘Xun 856’ as the male parent, and it was approved by the nation for Huang-Huai-Hai summer maize region in 2021. In this study, the breeding process, parent source and characteristics, yield performance, stress resistance, disease resistance and quality analysis of the variety were analyzed. The study proposed that in variety breeding, we should highlight the exploration and utilization of excellent germplasm resources, strengthen adversity selection and improve ecological adaptability of the varieties, so as to breed a new maize variety with high yield and quality, wide adaptability, density tolerance and strong stress resistance.

An Daoyuan1, Huang Bizhi2, Wu Bozhi1

By exploring the changes in the research field of fresh-eating corn in China, grasping the research status and hot topics, and discussing the research frontiers and development trends, the study aims to provide theoretical reference for the research of fresh-eating corn. The research team used 1588 fresh-eating corn research literature in the CNKI database from 2010 to 2021 as the research objects, and carried out visual quantitative analysis based on CiteSpace software. In the past 10 years, the research development in the field of fresh-eating corn was stable, and the number of core papers published per year remained above 100. The high-yield authors were represented by LU Weiping, LIU Chunquan, LI Dajing, LU Dalei, etc., presenting single-line or radial team cooperation. The institutions to which the authors belong were mainly agricultural colleges and universities and scientific research institutes. Agricultural colleges and universities achieved more significant results in terms of the number of publications, and scientific research institutes had more advantages in the research and development of new varieties, and scientific research institutions and universities had close team cooperation. The analysis of emerging words indicates that haploid, super sweet corn, seed germination, genetic diversity, nutritional quality, flavor, folic acid, soluble sugar, etc. are the research trends. The core task of future fresh-eating corn research will be expanding the research coverage, breaking through the traditional limitations, exploring gene editing technology, transgenic technology, gene sequencing, single-celled sequencing, genome, proteins, transcription and other cutting-edge biotechnologies which are auxiliary means for traditional fresh-eating corn breeding research, and the focus will be on sweet and waxy corn and super sweet corn research. The future research should also highlight the quality and nutrition of fresh-eating corn varieties, and improve their resistance to diseases and insects, lodging, drought and other stresses. In the fields of food processing and feed research, more attention should be paid to the technology development of new processing equipment for extending the harvesting period and storage period of fresh-eating corn and maintaining the nutrition of corn during storage.

【Objective】 Plant height is one of the important target traits in maize plant type breeding, which is closely related not only to mechanized grain harvesting and lodging resistance, but also to maize yield. Therefore, it is of great theoretical and breeding value to isolate QTL/gene of maize plant height and analyze its function. This study aims to locate a novel maize dwarf gene ZmDLE1, clarify its biological function, and provide important theoretical basis and gene resources for accelerating the improvement of maize plant type. 【Method】 A single recessive mutant was derived in maize inbred line LY8405, from Crop Research Institute of Gansu Academy of Agricultural Sciences, by chemical mutagenic agent Ethyl Methyl Sulfonate (EMS). A maize dwarf and low ear mutant was isolated from the M₂ progeny, and the M₃ and M₄ progeny could stably inherit, which was named dwarf and low ear mutant1 (Zmdle1). The F₂ population was constructed by hybridization with Mo17 and was identified by bulked segregate analysis-sequencing (BSA-seq) and target segment recombination exchange. Based on the Mo17 reference genome, the genes in the target region were obtained and functionally annotated to locate candidate genes.【Result】Phenotypic identification of Zmdle1 was carried out, and the phenotype of Zmdle1 at seedling stage was not significantly different from that of the control LY8405. The plant height and ear height of Zmdle1 at mature stage were reduced by 87.2 cm and 55.4 cm, respectively, accounting for about 35.0% and 62.9%, difference is extremely significant. Morphological observation showed that the decrease of internode number and the shortening of internode cell length were the main reasons for the significant decrease of plant height and ear height of Zmdle1. The genetic analysis of the mutant gene was conducted by using the F_2:3 genetic populations. The Zmdle1 mutant is inherited in a 3﹕1 (χ²=2.854) ratio and is a single recessive gene. Therefore, according to the results of BSA-seq, the candidate gene ZmDLE1 was initially located in the 15 Mb region of Bin1.09-1.10 on chromosome 1 of maize. The polymorphism molecular markers were further developed using the re-sequencing results of Mo17 and Zmdle1, and the target gene was accurately cloned by map-based cloning. Finally, the candidate genes were mapped to the size range of 600 kb, and there were 16 candidate genes in this range. By comparing the re-sequencing data, it was found that Zm00001d033231 gene changed into A at the 2062 position G, which resulted in amino acid changing from glycine to serine, and the transcription level expression was significantly reduced compared with LY8405. Zm00001d033234 changed from T to C at the 223rd position leading to the 75th amino acid changed from serine to proline, and there was no significant difference in transcription level. Through association analysis of natural populations and the predicted genes for functional annotation, it was found that Zm00001d033231 and Zm00001d033234 were related to the growth and development of maize. 【Conclusion】 The candidate gene ZmDLE1 in the Bin1.09 region at the end of chromosome 1, was identified to effectively regulate maize plant height and ear height, and the target region was reduced to 600 kb by fine localization. Association analysis showed that Zm00001d033231 was genetic locus significantly associated with plant height within the target region.

In order to study the small auxin-up RNA (SAUR) family of maize, this study identified by the genome-wide prediction approach 91 SAUR genes which named ZmSAURs, and analyzed the gene structure, amino acid characteristics, chromosomal location and genetic evolutionof ZmSAURs. The results showed that, the SAUR gene family were unevenly distributed on the chromosome, while the chromosome 2 up to 22 ZmSAURs. The amplification pattern of the gene was dispersed replication and fragment replication. The SAUR gene family has a relatively conserved structure, e.g. a conserved RNA DNA structure and the 3D structure of the deduced proteins that generally contained three alpha helices and three beta sheets. The phylogenetic tree analysis revealed 9 branches of SAUR proteins among species. As expected, SAURs in corn and relative millet (Setaria italic) were clustered together. Thus, this information provided by this work might be useful in future functional characterization of the maize SAUR gene family.

To meet the market requirement for high-yield and high-density resistance maize, the new maize variety‘Shengrui 999’was bred using‘Sheng 68’as female parent and‘Sheng 62’as male parent. In 2011- 2012 Huanghuai summer maize regional trial, the average annual yield was 10035.7 kg/hm2, which was 6.3% higher than that of the control‘Zhengdan 958’. In 2012 Huanghuai summer maize production trial, the average yield was 10336.5 kg/hm2, which was 7.1% higher than that of the control‘Zhengdan 958’. In 2013, the variety was approved by the Henan Provincial and National Crop Variety Approval Committee, its main features are high yield and stability, outstanding lodging resistance, high- density resistance and superior quality, and it is suitable for being planted in summer in Henan, Shandong, Baoding and the south of Hebei, Guanzhong Irrigation District of Shaanxi, northern Jiangsu, northern Anhui and southern Shanxi.

To adapt to dense planting of maize and meet the rapid mechanization development of agricultural production, the basic maize population was developed by using abroad excellent germplasm materials, then high-density and large-population selection, targeted inoculation and identification methods were adopted to obtain the new variety ‘Ruipu909’ with the disease-resistant self-line ‘RP86’ as female parent and ‘RP06’ as male parent. This variety has characteristics of density resistance, stress resistance, high yield and easy mechanical harvesting. The results show that the average yield of the regional test is 12589.5 kg/hm ², 7.1% higher than that of the control variety. There are 111 test points, the yield-increase points accounted for 93%. The yield of production test is 12601.5 kg/hm ², compared with the control variety, the yield increased by 7.7%, and there are 95% yield-increase points among the 54 test points. The average lodging rate in regional and production tests is 1.6%. ‘Ruipu909’ is resistant to northern corn leaf blight, stalk rot and ear rot. The crude starch content of seeds is 75.24%. In summary, the new variety ‘Ruipu909’ has multiple characteristics of high and stable yield, strong disease and lodging resistance, good quality, wide adaptability, density resistance and is suitable for mechanical harvesting. The variety was examined and approved by Shanxi Province in 2017 and was further approved by Shaanxi, Inner Mongolia and passed the national authorization in 2018. The variety is suitable for popularizing and planting in middle-late maturing areas of spring sowing regions in eastern north China and northwest China and Huanghuaihai summer maize areas in southern Shanxi.

To well understand the function of key enzymes and regulatory mechanism in starch synthesis, we reviewed the starch structure, starch synthesis process, expression profiles and functional mechanism of transcription factors for starch synthesis, including DOF family, NAC family, MYB family, bZIP family, MADS-BOX and AP2/EREB family. Researches show that most of the transcription factors are expressed in maize endosperm, and a few are expressed in maize leaves. Furthermore, these transcription factors could regulate starch synthesis by binding to the promoters of starch syntheses encoding genes and key regulatory genes to affect their expression. In addition, sucrose/ABA and sucrose/IAA with transcription factors also coordinately regulate the starch synthesis. Collectively, this research will not only enrich the knowledge of the regulating mechanism in maize starch synthesis, but also supply reference for breeding new maize varieties.

Under the background of the structural reform of agricultural supply side, through the empirical analysis of the purchase intention of Shanghai local brand fresh corn and its influencing factors, the study aims to better promote the brand building of fresh corn and provide the corresponding advices for guiding the consumption of local brand fresh corn. Through the establishment of multivariate and orderly Logit model, we quantitatively analyzed the individual characteristics, family characteristics of different consumer groups, the cognitive characteristics of consumer groups on fresh corn and the dietary preferences of consumers on the purchase intention of Shanghai brand fresh corn products and the direction of action. The results showed that: the gender, age, place of birth, education, consumer willingness to treat fresh corn as a snack, the awareness of the fresh corn production in Shanghai, the trust in the quality and safety of fresh corn products, and the place of origin were significant factors influencing consumers’ willingness to purchase local brand fresh corn. On the whole, the current information asymmetry between the market and consumer is still an important factor restricting the development of local brands and the consumption of high-quality agricultural products. Based on this, we put forward targeted suggestions from the precise positioning of consumer groups, reducing information asymmetry between market and consumer, and increasing the diversity of fresh corn products.

【Objective】Northeast China is the main grain production base in China, which has been significantly affected by climate change in recent years. It was of great significance to understand the impact of normal and extreme climate states changes on crop yield in Northeast China for regional crop production and national food security.【Method】In this study, the maize in Northeast China was used as research object, and the main climate factors affecting maize yield were screened to analyze the effects of normal and extreme climate states changes on maize yield in 81 counties in Northeast China from 1980 to 2018.【Result】(1) The average temperature, growing degree-days (GDD), and heat degree-days (HDD) during the maize growth period showed an increasing trend, and the rising rates were 0.34 ℃·(10 a)^-1, 47.07 ℃·d·(10 a)^-1, and 5.15 ℃·d·(10 a)^-1, respectively. The precipitation showed a decreasing trend, with the rate of 7.0 mm·(10 a)^-1; the average temperature, GDD, and HDD increased from northeast to southwest, while the precipitation increased from northwest to southeast. (2) The meteorological yield of maize in Northeast China showed an increasing trend from 1980 to 1999, with a rate of 80.93 kg·hm^-2·a^-1, while it showed a decreasing trend of 46.25 kg·hm^-2·a^-1 from 2000 to 2018. In terms of spatial distribution, it showed an increasing trend from the middle to the surrounding areas. The area with high yield was concentrated in the eastern part of Heilongjiang. The change of Liaoning was the most stable, and the fluctuation range was stable in the middle area. (3) By the multiple linear regression model, HDD contributed the most to meteorological yield from 1980 to 2018, and the effect was negative, which meant extreme high temperature had the greatest impact on maize yield in Northeast China and caused maize yield reduction; GDD had a positive effect, that is, the average temperature increased maize yield, and the greater GDD, the more yield increased; the precipitation had a negative effect; the interaction between temperature and precipitation had a positive impact on maize yield in Northeast China.【Conclusion】Normal and extreme climate states changes and its impact on maize meteorological yield in Northeast China from 1980 to 2018 were as follow: the normal and extreme temperature showed an overall increasing trend, while the normal precipitation showed a decreasing trend. Extreme high temperatures and normal precipitation led to a decrease in maize yield, but the average temperature increased maize yield, and the extreme high temperature had the greatest impact. In the future, it was necessary to make full use of the average temperature state and minimize the harm caused by extreme high temperature to ensure a high-stable maize production.

Objectives Chlorophyll content and water content are key physiological indicators of crop growth, and their non-destructive detection is a key technology to realize the monitoring of crop growth status such as drought stress. This study took maize as an object to develop a hyperspectral-based approach for the rapid and non-destructive acquisition of the leaf chlorophyll content and water content for drought stress assessment. [Methods] Drought treatment experiments were carried out in a greenhouse of the College of Agriculture, Guangxi University. Maize plants were subjected to drought stress treatment at the seedling stage (four leaves). Four drought treatments were set up for normal water treatment [CK], mild drought [W1], moderate drought [W2], and severe drought [W3], respectively. Leaf samples were collected at the 3^rd, 6^th, and 9^th days after drought treatments, and 288 leaf samples were collected in total, with the corresponding chlorophyll content and water content measured in a standard laboratory protocol. A pair of push-broom hyperspectral cameras were used to collect images of the 288 seedling maize leaf samples, and image processing techniques were used to extract the mean spectra of the leaf lamina part. The algorithm flow framework of "pre-processing - feature extraction - machine learning inversion" was adopted for processing the extracted spectral data. The effects of different pre-processing methods, feature wavelength extraction methods and machine learning regression models were analyzed systematically on the prediction performance of chlorophyll content and water content, respectively. Accordingly, the optimal chlorophyll content and water content inversion models were constructed. Firstly, 70% of the spectral data was randomly sampled and used as the training dataset for training the inversion model, whereas the remaining 30% was used as the testing dataset to evaluate the performance of the inversion model. Subsequently, the effects of different spectral pre-processing methods on the prediction performance of chlorophyll content and water content were compared. Different feature wavelengths were extracted from the optimal pre-processed spectra using different algorithms, then their capabilities in preserve the information useful for the inversion of leaf chlorophyll content and water content were compared. Finally, the performances of different machine learning regression model were compared, and the optimal inversion model was constructed and used to visualize the chlorophyll content and water content. Additionally, the construction of vegetation coefficients were explored for the inversion of chlorophyll content and water content and evaluated their inversion ability. The performance evaluation indexes used include determination coefficient and root mean squared error (RMSE). [Results and Discussions] With the aggravation of stress, the reflectivity of leaves in the wavelength range of 400~1700 nm gradually increased with the degree of drought stress. For the inversion of leaf chlorophyll content and water content, combining stepwise regression (SR) feature extraction with Stacking regression could obtain an optimal performance for chlorophyll content prediction, with an R² of 0.878 and an RMSE of 0.317 mg/g. Compared with the full-band stacking model, SR-Stacking not only improved R² by 2.9%, reduced RMSE by 0.0356mg/g, but also reduced the number of model input variables from 1301 to 9. Combining the successive projection algorithm (SPA) feature extraction with Stacking regression could obtain the optimal performance for water content prediction, with an R² of 0.859 and RMSE of 3.75%. Compared with the full-band stacking model, SPA-Stacking not only increased R² by 0.2%, reduced RMSE by 0.03%, but also reduced the number of model input variables from 1301 to 16. As the newly constructed vegetation coefficients, normalized difference vegetation index(NDVI) [(R₄₁₀-R₅₅₉)/(R₄₁₀+R₅₅₉)] and ratio index (RI) (R₄₀₀/R₁₁₇₁) had the highest accuracy and were significantly higher than the traditional vegetation coefficients for chlorophyll content and water content inversion, respectively. Their R² were 0.803 and 0.827, and their RMSE were 0.403 mg/g and 3.28%, respectively. The chlorophyll content and water content of leaves were visualized. The results showed that the physiological parameters of leaves could be visualized and the differences of physiological parameters in different regions of the same leaves can be found more intuitively and in detail. [Conclusions] The inversion models and vegetation indices constructed based on hyperspectral information can achieve accurate and non-destructive measurement of chlorophyll content and water content in maize leaves. This study can provide a theoretical basis and technical support for real-time monitoring of corn growth status. Through the leaf spectral information, according to the optimal model, the water content and chlorophyll content of each pixel of the hyperspectral image can be predicted, and the distribution of water content and chlorophyll content can be intuitively displayed by color. Because the field environment is more complex, transfer learning will be carried out in future work to improve its generalization ability in different environments subsequently and strive to develop an online monitoring system for field drought and nutrient stress.

With the change of the examination and approval system, a large number of new maize varieties have emerged in the market. In order to select new maize varieties suitable for regional production in northern Henan and guide local maize production, ‘Zhengdan 958’ was used as control to compare the adaptability, stress resistance and harvest of 30 newly approved maize varieties under field condition. The results showed that the growth period of the tested varieties was 114-120 days, and all the varieties could mature normally in northern Henan, and the male and female could meet normally in the flowering period; the yield of the tested varieties was 8726.97-11973.68 kg/hm², significantly increased compared with that of control. The yield of ‘Yudan 1851’, ‘Dehe 187’, ‘Yunong76’, ‘Zhongbo 510’, ‘Xundan 1538’, and ‘Luoyu 16’ increased by 10.4%, 8.9%, 7.5%, 7.3%, 5.8% and 4.5%, respectively, among them, the water content of ‘Yudan 1851’, ‘Dehe 187’, ‘Yunong76’, ‘Zhongbo 510’ and ‘Xundan 1538’ was relatively low at harvest time, 21.5%, 21.7%, 19.1%, 19.6% and 18.2%, respectively. The results indicate that five of the 30 varieties, such as ‘Xundan 1538’ and so on, have the characteristics of mechanized grain harvesting in northern Henan.

【Objective】 Drought is one of the serious abiotic stresses influencing maize production worldwide. Understanding the molecular mechanisms underlying drought tolerance is of great importance in maize improvement. 【Method】 In the present study, representative maize inbred lines were selected for field drought experiment and the drought tolerance was estimated based on leaf relative water content and anthesis-silking interval. Two inbred lines with contrasting drought tolerance was used for genome resequencing and transposable element insertions were identified. The DNA methylation level of leaf and root tissues under different water treatments of the two lines were measured using Whole Genome Bisulfite Sequencing (WGBS). And the gene expression profiles of these samples were detected by RNA sequencing. The integrative atlas of transposable element insertion/deletion variants, differentially methylated regions and differentially expressed genes in the two lines were constructed. In addition, the transposable element insertion/deletion variant mediated epigenetic regulation of ZCN7, which has been conferred the drought tolerance function in our previous study, was analyzed. 【Result】 The field experiment showed inbred line H082183 showed highest drought tolerance, in which the leaf relative water content and anthesis-silking interval had no significant difference between drought and well-watered treatments. While the Lü28 displayed lowest leaf relative water content and largest anthesis-silking interval under drought. Thus, these two lines were selected for further analysis. A total of 333 754 and 333 296 transposable element insertions were identified in the genome of H082183 and Lü28, respectively. And 89 954 transposable element insertions were polymorphism between two lines. The transposable element insertions, introns and promoters showed higher CG and CHG methylation level than exons and untranslated regions. Furthermore, 41 352 differentially methylated regions were identified between H082183 and Lü28. And 60% of the differentially methylated regions were located in the transposable element insertion\deletion variants and 5 kb flanking regions. The gene expression level showed negatively correlated with CG and CHG methylation. Differentially expression analysis between H082183 and Lü28 obtained 4 196 and 3 500 differentially expressed genes in leaf and root under drought, respectively. The 19.5% and 19.7% of these differentially expressed genes were located in differentially methylated regions. Three LTR transposable element insertions were identified in the 34 kb region of ZCN7 in Lü28 but absent in the genome H082183. And the DNA methylation levels of CG and CHG in this genomic region were significantly higher in Lü28 than H082183 under both drought and well-watered environments, which conferred higher ZCN7 expression in the drought tolerant line H082183. 【Conclusion】 Our results highlight the important role of interplay of transposable element insertions, DNA methylation and gene expression under drought. And gene expression regulation mechanism of ZCN7 relied on the transposable element insertion/deletion variants mediated DNA methylation was proposed.

【Objective】The objective of this study is to perform the genome-wide identification of the maize ACO (1-aminocyclopropane- 1-carboxylate oxidase) gene family, analyze its expression patterns in different organs and developmental stages of maize, as well as in response to exogenous hormones and pathogen infection, and to lay the foundation for clarifying the function of the maize ACO gene family.【Method】Using bioinformatics methods, the ACO was identified in the genome of maize B73 inbred line, and its gene structure, protein physicochemical properties, phylogenetic relationships among family members, and conserved motifs were analyzed. The expression patterns of the ZmACO gene family were analyzed using real-time fluorescence quantitative PCR (qRT-PCR) technology.【Result】Except for ZmACO11, all members of the ZmACO family have Fe²⁺ binding sites and substrate ascorbic acid binding sites. The phylogenetic tree showed that ZmACO2 and ScACO are in the same branch and have a close genetic relationship, with a Bootstrap value of 98. The gene expression analysis indicated that ZmACO2, 5, 9, 15, 20 and 35 were actively expressed at various developmental stages and exhibited dominant expression in leaves, so the six genes mentioned above were selected for the next step of testing. Spraying ethephon resulted in fluctuations in the expression of all six genes mentioned above, the expression level of ZmACO2 was significantly affected, with a variation multiple of about 8 times. The expression levels of these six genes fluctuated within 0-24 h of ethephon treatment. But after 24 h of treatment, all gene expression levels were close to 0. After salicylic acid treatment, the expression level of ZmACO5 was significantly affected, with a variation multiple of about 2 times. The expression levels of other genes were close to 0 at 24 h after treatment. The expression levels of ZmACO9, 35 fluctuated between 3 to 12 h, and the expression levels of ZmACO2, 15, 20 showed a downward trend. In response to biological stress, the expression levels of ZmACO5, 9 showed the greatest changes after inoculation with the Setosphaeria turcica, and on the 10th day after inoculation, the expression levels of these two genes increased by 50 and 60 times, respectively, compared to the control group. After inoculation with the Cochlibolus heterostrophus, the expression level of ZmACO5 changed significantly, with a variation multiple of 40-90 times. After inoculation with Rhizoctonia solani, the expression levels of ZmACO5, 35 showed the greatest changes, reaching 200 times on the 3rd day of inoculation.【Conclusion】The expression changes of ZmACO2, 5, 20 and 35 are most active during the growth and development of maize; The application of exogenous ethephon and salicylic acid can significantly affect the expression level of ZmACO genes. The expression level of ZmACO genes significantly changes after bacterial infection in maize, which is closely related to the response to biological stress.

Considering the ecological environment of Sichuan area, an experiment was conducted to breed new corn varieties with high yield, high quality, multi resistance and wide adaptability. According to the principle of gene recombination, the authors combined the local tropical germplasm with PB germplasm, which was rich in disease- resistant, lodging- resistant and drought- tolerant genes, and the integration was used as the innovative strategy for breeding. Inbred-line‘LSC 107’was successfully bred and the new corn hybrid‘Wande No.1’was bred by crossing‘LSC 107’with‘Yi 99-19’. The results showed that the corn hybrid had good performance, including high yield, good stability, high quality, excellent disease resistance and lodging resistance, and wide adaptation. So it was adaptable for planting in plain and hilly areas of Sichuan Province. With hybrid recombination between local tropical germplasm and PB inbred lines, the inbred-line had high general combining ability and strong adaptability, and the hybrid had high yield, high quality and wide adaptability, and had broad prospects of popularization and application.

【Objective】In the context of intensified global climate change and frequent meteorological disasters, exploring the significance of meteorological factors on maize yield and accurately predicting maize yield is crucial for enhancing agricultural production and field management. This paper aims to quantitatively analyze the importance of meteorological factors during various growth stages of maize on yield and to establish a highly accurate and reliable maize meteorological yield stacking ensemble learning estimation model for yield prediction.【Method】Using the HP filter method and moving average method, trend yield models for various counties were determined, and county-level meteorological yields were isolated. Three ensemble learning methods (light gradient boosting machine (LightGBM), Bagging, and Stacking) were employed. By analyzing daily meteorological data and maize yield data over 34 years from 596 county-level administrative regions and meteorological observation stations across 12 provinces in China, three maize meteorological yield prediction models based on different ensemble learning frameworks (LightGBM, Bagging, and Stacking) were established.【Result】The HP filter method as the trend yield model was mainly applicable in the regions of Shaanxi, Henan, Jiangsu, and Anhui. Compared to the HP filter method, more counties were suitable for the moving average method, with most counties having the R² distribution above 0.8. Based on a 5-year sliding forecast and model accuracy evaluation indicators, the mean absolute percentage error (MAPE) for the three models on maize yield was below 6%. The Stacking model achieved a MAPE of 4.60%, indicating high prediction accuracy and strong generalizability. The results demonstrate that the maize meteorological yield stack-integrated learning prediction model has higher accuracy and stronger robustness. It effectively utilizes the characteristics and advantages of each base learner to improve prediction accuracy, making it the optimal model for predicting maize yield based on meteorological factors. Furthermore, a quantitative analysis of the impact of 27 meteorological factors during the maize growth stages in 12 provinces, using the random forest feature importance score, is of reference value for crop monitoring and field management.【Conclusion】The three ensemble learning methods, especially the stack-integrated learning model (Stacking), can accurately reflect the spatiotemporal distribution changes in maize yield. The stack-integrated learning model for maize yield based on meteorological factors provides a new method for field management and accurate prediction of maize yield.

To obtain new maize varieties with high yield, drought resistance, lodging resistance and disease resistance, Research Center of Modern Agriculture of Shanxi Academy of Agricultural Sciences combined traditional breeding methods and modern biotechnology to make full use of high-quality American germplasm resources, aiming to improve excellent inbred lines bred by the center. T0725 and T0750 inbred lines were obtained through hybridization and second cycle breeding, associated with molecular assisted resistance identification methods. Then test-cross, variety comparison test and production test in different ecological test sites were conducted to obtain the new maize variety‘Sheng Yu688’which had characters of wide adaptability, good agronomic characters and high yield, and the yield increased by 5% and above compared with that of CK, and had moderate resistance to blight, ear rot and rough dwarf disease. The variety was approved by Shanxi Variety Approval Committee in 2016.‘Sheng Yu688’has high yield, high quality, multi resistance and dense-resistance, with features as follows: the bulk density of 735 g/L, crude protein content of 10%, crude fat content of 3.72%, crude starch content of 72.56%, which indicated that it was a high starch variety; its seed rate is 87.1%, the average yield reaches 11841 kg/hm2. The seed production technology of the variety is simple and convenient, with high yield and reduced production cost.

The purpose of this research is to construct a compound microbial agent to degrade corncobs, use biomass energy efficiently and decrease environmental pollution. In this study, cow dung and the fermented substrate of cow dung mixed with corncob were used as tested materials. The cellulose-degrading bacteria were screened through Congo red staining and filter paper enzyme activity (FPA), and the strains were identified. The obtained strains were subjected to antagonism analysis by the streaking method. Finally, the strains were compounded and inoculated into the corncob to study the fermentation effect. The results showed that the enzyme activities of strains BC-2W, BC-2Y, BC-7W, BC-7Y, BC-12Y, BC-15W, BC-15Y, B1-2, B1-11, B2-7, B2-8 and B2-9 obtained from both kinds of fermentation substrates were all higher than 9.0 U/mL, and the cellulose degradation rate of corncob inoculated with compound microbial agent reached (55.63 ±2.21)%, which was higher than that of corncob inoculated with cow dung. Infrared spectroscopy, X-ray diffraction analysis and scanning electron microscope results showed that the degradation degree of lignocellulose in corncob inoculated with compound microbial agent was higher than that of cow dung group. The compound microbial agent could degrade corncob effectively, and it had great application prospect in cellulose degradation and utilization of biological resources of corncob.

In this study, through the study of the relevant literature, in the grasp of a certain research methods and theoretical basis under the premise of the design of the questionnaire, the "urban residents in Beijing urban fresh consumption characteristics of consumption," one to one face to face interviews with consumers, access to The research data of the purchase and consumption of fresh corn in urban residents of Beijing were analyzed. The data of the survey were analyzed by descriptive statistics and cross analysis. The market segmentation was carried out according to the different purchase and consumption characteristics of fresh corn.The study shows that with the increase of education and income, consumers choose to increase the proportion of fresh edible corn in high-end restaurants and canteen, and the sensitivity to fresh corn prices is reduced. The places of outdoor consumption of fresh corn, Enterprises and institutions are mainly in the unit canteen, urban freelancers are mainly in the general restaurant, individual businessmen are mainly in the roadside temporary dining places, retirees and unemployed persons are mainly in the general restaurant and roadside places; with The increase in age, the consumption of fresh corn by the impact of the more obvious the degree of attention to the price gradually increased; men prefer to eat in high-end places when eating fresh corn, women prefer the convenience of the roadside consumption. When buying fresh corn, women are more likely to be affected by the season than men. According to the characteristics of consumers to buy and consume fresh corn, the fresh corn will be subdivided into two sub-markets: emotional motives sub-market and rational motive sub-market. Consumers of emotional motivational market, with the need to buy and emotional experience to buy the dominant features in the purchase and consumption of fresh corn, the more concerned about the psychological and material needs and other factors; rational motive sub-market consumers , With objectivity, thoroughness, control characteristics, in the purchase and consumption of fresh corn, the more concerned about the product attributes, the purchase environment, the cost of consumption and other factors;

To elucidate the effects of nitrogen fertilizer application rate on sugar content and agronomic traits of sweet corn (Zea mays L. var. saccharata Bailey), a field experiment was conducted with sweet corn variety “Yuntian 8” as the material, and five treatments were set up with nitrogen fertilizer application rate of 0, 100, 200, 300 and 400 kg N/hm². The results showed that, the linear models of the relationship between nitrogen fertilizer application rate and soluble sugar content and reducing sugar content were not significant, only on the 103^rd day after sowing, the reducing sugar content decreased slightly with the increase of nitrogen fertilizer application rate. The response of ear weight to the increase of nitrogen fertilizer application rate presented an asymptotic growth model. When nitrogen application rate exceeded 100 kg N/hm², the extent of the positive response of ear weight to nitrogen application decreased dramatically. Each increment of 100 kg N/hm² decreased the ear length by 0.29 cm. The linear models of the relationships between nitrogen fertilizer application rate and ear diameter, ear row number and grain number per row were not significant. Increasing nitrogen fertilizer application rate could decrease bare tip length. Taken together, increasing nitrogen fertilizer application rate could not affect sugar content, ear diameter, ear row number and grain number per row of sweet corn, and slightly decrease ear length. However, increasing nitrogen fertilizer application rate could significantly increase ear weight and decrease bare tip length.

The performance and characteristics of the new corn hybrid ‘Zhongkeyu 505’ are reported here to provide theoretical and practical information needed for large-scale commercialization of this hybrid. ‘Zhongkeyu 505’ was developed by crossing CT1668 as female parent and CT3354 as male parent. The yield performance, agronomic traits, drought resistance, high temperature tolerance, density tolerance, grain quality, and silage forage quality were analyzed based on the multi-year and multi-location data from national and provincial trials. The results showed that the yield of this hybrid increased by 3.4% and 8% respectively on average compared with that of the two check hybrid ‘Xianyu 335’ and ‘Zhengdan 958’. The ear characters such as ear length, ear diameter, kernel number per row, grain weight per ear and grain yield were better than those of the check hybrid. The drought tolerance reached the extremely strong standard, and the high-temperature tolerance reached the medium level equivalent to that of the check ‘Zhengdan 958’. The grain test weight was 746 g/L, the crude protein, crude fatty acid, crude starch, and lysine content reached 10.1%, 3.36%, 74.26%, and 0.3% respectively. The relative stalk feed quality was better than that of ‘Xianyu 335’ and ‘Zhengdan 958’. This hybrid is an excellent one of significant commercial value. In the process of commercial breeding of maize, special attention should be paid to the factors of the market safety evaluation of new varieties, seed production yield, stem rot, ear rot, Southern and Northern leaf blight, Southern rust, suitable planting density and lodging control etc., thus establishing a breeding method combining limited backcrossing with large population adversity screening.

K12 self-bred line was bred by the self-bred line with high- combining ability Huangzaosi and material with subtropical germplasm in southwest of China. The authors had integrated the recurrent selection in corn strain population with the pedigree method. K12 self-bred line is extensively in all over China because it has high combining ability, high resistance to adversities, wide adaptabilities and the superior comprehensive agronomic properties. Since the 90th of this century, over 10 hybrid maize varieties have been combined with K12 self-bred line with 4.67 million hectares planting area. K12 self-bred line played significant roles in the maize breeding and production in China.

Maize (Zea mays L.) can exhibit yield penalties as a result of unfavorable changes to growing conditions.  The main threat to current and future global maize production is heat stress.  Maize may suffer from heat stress in all of the growth stages, either continuously or separately.  In order to manage the impact of climate driven heat stress on the different growth stages of maize, there is an urgent need to understand the similarities and differences in how heat stress affects maize growth and yield in the different growth stages.  For the purposes of this review, the maize growth cycle was divided into seven growth stages, namely the germination and seedling stage, early ear expansion stage, late vegetative growth stage before flowering, flowering stage, lag phase, effective grain-filling stage, and late grain-filling stage.  The main focus of this review is on the yield penalty and the potential physiological changes caused by heat stress in these seven different stages.  The commonalities and differences in heat stress related impacts on various physiological processes in the different growth stages are also compared and discussed.  Finally, a framework is proposed to describe the main influences on yield components in different stages, which can serve as a useful guide for identifying management interventions to mitigate heat stress related declines in maize yield.

Aiming at recent decade drought stress on Spring maize production in Nanzheng, a comparison of the precipitation distribution between 1966-2000 and recent decade are made, and it is put forward that ensure of seeding temperature the start seeding date is ten days ahead can adapt precipitation distribution better and the harm of drought is reduced. The effect of early seeding in low temperature and cultivate free and double covering on reducing soil water evaporation and enlarging soil capacity of absorbing precipitation and increasing the efficiency of precipitation usage are put forward through field soil water measurement.

The aim of this study is to isolate and identify endophytic bacteria with growth-promoting function from maize seeds, and to provide strain resources and technical support for the research and development of bacterial fertilizer. In this experiment, maize seeds were used as the test materials, and endophytic bacteria were isolated and purified by plate coating and three-zone marking method. Drip irrigation test was used to screen growth-promoting strains. The fermentation conditions were optimized by single factor test and orthogonal test. The promoting effect of the strains was verified by pot drip irrigation test. Bacillus subtilis was isolated and identified as SYL4, which had a relatively strong growth-promoting effect. The optimal culture condition for SYL4 was: peptone 1.5%, corn flour 0.5%, CaCO₃ 0.25 %, inoculation volume 5%, rotation speed 200 r/min, temperature 34℃, and incubation time 48 h. Drip irrigation of maize with fermentation broth increased root length and leaf length by 12.86% and 9.4%, root weight and leaf weight by 6.52% and 6%, respectively. In this study, an endophytic bacterium SYL4 with growth-promoting potential was isolated. The optimized fermentation condition increased the activity of peroxidase (POD) in maize seedlings and effectively promoted the growth of maize seedlings.

【Objective】The main producing areas of maize is mostly located on the arid or semi-arid region that relying on the rainfed farming in China. The maize production losses caused by drought is a great threaten to food security. As a cross-pollinating crop, maize is mostly sensitive to water stress during flowering time. Drought at flowering stage will lead to asynchronous development between the male and female flower and cause massive grain yield loss. Thus, mining drought resistance related genes at flowering stage is important for maize drought resistance improvement and breeding. 【Method】In the present study, the phylogenic tree of 24 ZCN genes in maize genome, which is homologs of Arabidopsis FT gene, was build. The gene expression patterns of ZCN7 were analysis using qRT-PCR and in vivo GFP fluorescence imaging. A maize natural population consisting of 118 diverse inbred lines were planted in three environments, Beijing in 2021 and 2022 and Urumqi in 2022, to identify the flowering time related traits under different water treatments. The genomic variants around ZCN7 were detected by PCR and Sanger sequencing. The candidate gene association analysis was performed based on mixed linear model and the significant associated variants with drought induced anthesis-silking interval was obtained. The gene expression level of ZCN7 in natural population at flowering time was also measured by qRT-PCR. The differences of drought resistance traits and ZCN7 expression were compared between different haplotypes of significant associated variant. The Ubi1:ZCN7 overexpression transgenic maize were obtained, and the phenotypic performance was identified under different water treatments. 【Result】The 24 ZCN genes in maize genome included 15 FT like genes, 6 TFL1 like genes and 3 MFT like genes. The protein sequence of ZCN genes varied from 111 nn to 193 nn. The ZCN7 showed close relationship with ZCN8 and the protein sequence identity was 83.3% between the two genes. ZCN7 showed highest gene expression in the leaf blade at V12 stage. And the ZCN7-promoter:GFP vector was transformed to Arabidopsis and the GFP showed enriched signal at the blade edge of mature leaf. The candidate gene association analysis revealed a SNP variant at 1001 bp upstream of ZCN7 start codon had highest association signal with drought induced anthesis-silking interval under drought. The A/A and G/G haplotypes of SNP-1001 included 78 and 27 inbred lines, respectively. The anthesis-silking interval of A/A haplotype lines were significantly lower than G/G lines. And the ZCN7 gene expression of A/A haplotype lines were significantly higher than G/G lines. In addition, the ZCN7 overexpression transgenic lines showed significantly decreased anthesis-silking interval than wild type lines. Under drought, the anthesis-silking intervals of OE1 and OE2 were 2.3 and 2.6 days shorter than wild type lines. And the grain yield per plant and kernel number per plant of transgenic lines were significantly higher than wild type lines under drought, while the hundred kernel weight, kernel length and kernel width showed no significant difference. 【Conclusion】The maize ZCN7 played positive role in drought resistance and its overexpression improved grain yield by reducing anthesis-silking interval under drought.

To explore the natural variations in regulating the maize kernel development and to assist in the genetic improvement of maize yield traits, in this study, 150 maize inbred lines with rich genetic variations were selected as materials for investigation. Combining 34,342 SNP markers and three models, a genome-wide association analysis was conducted on five grain-related traits. The results revealed that a total of 18 independent loci were significantly associated with the target traits, with each locus accounting for 12.24% to 15.41% of the phenotypic variations. Additionally, significant epistatic interactions were identified among four pairs of SNPs associated with kernel length, collectively explaining 5.32% of the phenotypic variations. By integrating the dynamic transcriptome data of kernel development in the B73 inbred line and functional annotations of genes, 19 candidate genes were predicted and classified into four categories: 6 enzymes, 3 ribosomal proteins, 1 transcription factor, and 9 other proteins. These candidate genes provide new genetic resources for deciphering the molecular mechanisms of maize kernel development and enhancing maize kernel size and yield. Through this research, we have not only uncovered the natural variations that regulate the development of corn kernels but also provided new genetic resources for the genetic improvement of corn yield traits. These findings are expected to bring new breakthroughs in corn breeding efforts, enhance corn production, and thereby better meet human needs for food.

The Paper will discuss influence of liquid chlorine and chlorine dioxide and mixture of both on livingness of Maize root population. The result of experiment show that liquid chlorine in great does poisoned root, and reduced obviously activity of roots. Other disinfectors have no effect on activity of roots, but affect livingness of Maize Root-population. And the right dose of liquid chlorine is 8mg/l，the right dose of chlorine dioxide is 6mg/l, the right dose of mixture is （4＋2）mg/l.