Maize root system plays a crucial role in the development of the aboveground plant and determines the yield through the uptake of water and nutrients in the field.  However, the genetic architecture of the maize root system is largely unknown mainly due to its complexity and the interactions between genotype and environment.  Using a high-throughput semi-automatic hydroponic platform with stable conditions, we comprehensively characterized the root system in a core population of 518 diverse inbred lines of maize.  Population structure analysis revealed that the panel has stratification and a linkage disequilibrium decay distance of less than 50 kb.  Based on genotyping with the high-density 600 K SNPs, we conducted a genome wide association analysis (GWAS) and identified nine SNPs and seven candidate genes significantly associated with 24 traits.  One candidate gene, GRMZM2G400533, is located at the upstream 5 kb region from the leading SNP (AX-91771718) and was significantly associated with primary root length and preferentially expressed in the primary root and crown root.  Expression of GRMZM2G400533 increased as the primary root developed but was negatively correlated with primary root elongation.  An analysis of candidate gene GRMZM2G400533 identified three functional variants and eight allelic haplotypes.  This study will broaden our understanding of maize root development and provide a theoretical basis for maize improvement through optimization of the root system.

【Objective】To clarify the molecular characteristics and the effectiveness of target traits of transgenic maize LD05 with composite insect and herbicide resistance, and to provide data basis, technical support and product reserve for industrial application.【Method】Using biological information analysis, we designed and modified the proprietary insect-resistant fusion gene m2cryAb-vip3A, and selected BC₄F₃, BC₄F₄ and BC₄F₅ generations of the newly created transgenic hybrid insect-resistant and herbicide-tolerant maize LD05 to carry out experimental research. Specific PCR and Southern blot were used to analyze the stability of genomic integration. qRT-PCR and ELISA were used to analyze the expression stability. The resistance to target pests was evaluated by bioassay and field trials, and the herbicide tolerance was tested by field spraying of glufosinate. 【Result】A new insect-resistant fusion gene m2cryAb-vip3A with independent property right was discovered and designed, and a multivalent insect-resistant and herbicide resistant maize transformant LD05 was created. The exogenous T-DNA was integrated into the maize genome in the form of a single copy. The qRT-PCR results indicated that m2cryAb-vip3A and bar were both expressed in various tissues and organs across three generations, and the variation trend of expression quantities was largely consistent. Specifically, the expression level of m2cryAb-vip3A was the highest in the leaves at the seedling stage of the three consecutive generations, with an average expression quantity of 36.73, while the expression level was the lowest in the cob at the mature stage, with an average of merely 0.91. The expression pattern of bar was similar to that of m2cryAb-vip3A, with the highest expression level in the leaves at the seedling stage, averaging 7.35, and the expression level decreased after the jointing stage. The ELISA results demonstrated that M2CryAb-VIP3A could stably accumulate in different organs and at different periods in the three generations, and the protein accumulation amounts in different generations were similar. Among them, the accumulation amount was the highest in the leaves at the seedling stage of different generations, all exceeding 19.67 μg·g^-1 fresh weight. The expression of the targeted protein at a relatively high level could be detected in different tissues of the PAT transgenic plants of three consecutive generations, and there was no significant difference in the expression quantity between different generations. Among them, the expression level was the highest in the leaves at the seedling stage of different generations, with an average content of 16.61 μg·g^-1 fresh weight, while the accumulation amount was the lowest in the roots at the mature stage, with an average content of 0.30 μg·g^-1 fresh weight. The bioassay result showed that the corrected mortality of Ostrinia furnacalis, Spodoptera fragiperda and Mythimna separata reached 100% after feeding on V5 maize leaf tissue of LD05 for 96 h, which was a high resistance level. The results of field trials showed that LD05 transformants had high resistance to Ostrinia furnacalis at V5 stage and silking stage, to Mythimna separata at V5 stage, and to Helicoverpa armigera at silking stage. The results of glufosinate tolerance test showed that transgenic maize LD05 could tolerate 4-fold glufosinate. Agronomic character investigation showed that there was no difference between transgenic maize LD05 and control maize Zheng 58.【Conclusion】A novel insect-resistant fusion gene m2cryAb-vip3A with independent property rights was developed, and a transgenic hybrid insect-resistant and herbicide-tolerant maize LD05 was created with clear molecular characteristics, genetic stability and outstanding functional traits.

【Objective】Increasing planting density is a key agronomic strategy to enhance maize yield; however, excessive density may result in an imbalanced population structure, reduced utilization efficiency of limited resources (e.g., light), and suppressed yield potential. Gene editing can optimize canopy architecture through targeted improvement of maize plant type, thereby enhancing adaptability to high-density planting and boosting yield. Elucidating the effects of plant type improvement on root-shoot characteristics, grain yield, and density response in spring maize, as well as the underlying mechanisms, will provide theoretical and technical foundations for optimizing plant type and achieving high-yield dense planting in spring maize.【Method】The field experiment was conducted at Gongzhuling farm in Jilin, China. In this study, two maize hybrids, includding Jingke 968 and the improved plant types Jingke Y968, were grown with 60 000 plants/hm² (D1), 75 000 plants/hm² (D2) and 90 000 plants/hm² (D3) in 2019 and 2020, respectively. The effects of two plant types of spring maize of the same genetic background on the root-canopy characteristics and yield of spring maize were studied.【Result】Under normal density conditions (D1), there were no significant differences in leaf area index (LAI), net photosynthetic rate (Pn), PAR utilization (PUE), dry matter accumulation and grain yield between the two different plant types spring maize cultivars. However, compared with Jingke 968, under D3 conditions, the improved plant type Jingke Y968 had a relatively high number of main roots (7.2%) and a relatively large weight of root dry matter (6.0%), which promoted the absorption of nutrients; furthermore, under D2 and D3 conditions, Jingke Y968 significantly improved the canopy structure of maize, so that the upper, middle and lower parts had relatively low leaf angles, higher leaf orientation and LAI, and the excellent canopy structure increased the Pn of mid-to-late ear leaves of (7.5% (D2) and 7.7% (D3)) and PUE (4.3% (D2) and 10.8% (D3)). The structural equation results showed that higher leaf direction values and LAI could positively and directly increase the accumulation of dry matter in the aboveground, thereby increasing grain yield (8.7% (D2) and 11.2% (D3)).【Conclusion】In summary, the improvement of plant type enabled Jingke Y968 to have higher main root number and larger root dry matter weight under high-density conditions, which was conducive to nutrient absorption in the underground part. Meanwhile, its leaves were more compact, Pn was significantly increased, PUE was effectively improved, and root-canopy characteristics were more reasonable, which promoted dry matter accumulation in the above-ground part. Thus, the relatively high grain yield could be obtained.

The aim of this study was to provide scientific guidance for the promotion and cultivation of new sweet-waxy maize varieties. In order to explore the effects of different planting densities on the yield and main agronomic traits, in this experiment, the sweet-waxy maize varieties ‘Guitiannuo 108’ and ‘Guitiannuo 189’ were used as experimental materials, and five density levels were set as 40000, 46667, 53333, 60000 and 66667 plants/hm², as well as two sowing dates in spring and autumn. The results showed that the yield per plant, ear length, ear diameter and stem diameter decreased with the increase of planting density; while the yield per unit area and cob tip bald length increased with the increase of planting density. Considering yield and economic benefits comprehensively, the reasonable planting density for ‘Guitiannuo 108’ and ‘Guitiannuo 189’ in Guangxi is 46667-53333 plants/hm².

This study aims to systematically summarize the application of maize live haploid technology in maize molecular breeding, with focus on exploring the selection methods, formation mechanisms, identification methods, doubling methods, and application in population improvement of maize live haploid high-frequency induction lines, providing reference and guidance for the large-scale application of live haploid breeding technology. This study used a literature review method to summarize the relevant research results and practical experience on maize haploid technology, and analyzed the advantages and disadvantages of various methods in practical applications. The research results indicated that maize live haploid technology played an important role in breeding excellent inbred lines and population improvement. Through high-frequency induction line breeding, a large number of excellent haploid plants had been successfully obtained; the identification and doubling methods effectively improved haploid formation and stability. The live haploid technology had shown significant doubling effects in population improvement, providing new ideas and methods for maize breeding. In summary, maize live haploid technology is an efficient and rapid breeding method with broad application prospects. In the process of corn breeding, combining live haploid technology can accelerate the pace of quality improvement and yield increase, providing strong support for the healthy development of the corn industry.

Based on the practice of belt shaped composite planting of soybean and corn,the advantages and key points of its planting technology were summarized and analyzed, the problems in the application of the technology were pointed, and specific application strategies were propoesd. The spatial layout of soybean corn strip intercropping is reasonable, which is conducive to improving land use efficiency, increasing crop yield, and improving the ecological environment. The key cultivation techniques of this model include planting model selection, variety selection, suitable sowing, reasonable fertilization, chemical weed control, chemical pest control, and mechanical harvesting. In terms of production, this model currently has issues such as differences in sowing and harvesting machinery, inconsistent occurrence of pests, diseases, and weeds, and inconsistent prevention and control agents; in this regard, it is proposed to strengthen cooperative research and development, accelerate the development of new specialized machinery, improve the adaptability of machinery, select corn varieties resistant to soybean herbicides, strengthen the development of new pesticides, and thereby pay attention to field management and assist in achieving double harvests in one field. This article provides a reference for further promoting the belt shaped composite planting technology of soybean and corn.

Summer corn Shangdan1967 was used as test material, 4 treatments were set up: no biochar (CK), biochar 10 t/hm² (T₁), biochar 20 t/hm² (T₂) and biochar 40 t/hm² (T₃). The effects of biochar on photosynthetic characteristics such as chlorophyll content (SPAD value), net photosynthetic rate; superoxide dismutase (SOD), peroxidase (POD) activity and other physiological characteristics,and yield were analyzed. The results showed that T₂ and T₃ treatments could increase SPAD value, net photosynthetic rate, and transpiration rate, and reduce intercellular CO₂ concentration, with statistically significant difference compared with CK (P<0.05). Biochar treatment could increase SOD and POD activities, and increased with the increase of biochar application amount, that was T₃>T₂>T₁>CK. The content of malondialdehyde (MDA) in ear leaves was decreased with the increase of biochar application, that was, CK>T₁>T₂>T₃. Biochar treatment increased the yield of summer corn, and the yield of T₁, T₂, and T₃ increased by 5.80%, 9.98%, and 16.88% compared with CK. In conclusion, the application of biochar can improve the photosynthetic performance of maize post-ear leaves, increase the antioxidant enzyme activity of ear leaves, delay the senescence of ear leaves, and thus increase corn yield, and the application rate of 40 t/hm² has the best yield increase effect.

The production practice of fresh corn was combined in the Ili River Valley region, Xinjiang, its high yield planting techniques and application prospects were summarized and analyzed. In terms of high yield cultivation techniques for fresh corn, including selecting high quality varieties with good adaptability and disease resistance; adjusting the sowing date and method based on local climate differences and crop varieties; fine soil preparation, using precise sowing techniques; reasonably plant closely according to the characteristics of different corn varieties, adopting spatial isolation, temporal isolation, or natural barrier isolation for planting isolation, fertilize and irrigate according to the needs of each growth stage of corn, and adopting ecological management, agricultural control, biological control, and physical induction control methods for green pest control; timely harvest and carry out preservation treatment. Fresh corn is widely used in the fields of agriculture, industry, and animal husbandry. Its high quality and efficient production is of great significance in ensuring food security, meeting market demand, increasing grow’ income, promoting agricultural modernization, and promoting industrial integration and development. This article provides a reference for high quality and efficient production of fresh corn in the Ili River Valley and related areas.

This study investigated the effects of combining controlled-release nitrogen (CRN) fertilizer on nitrogen absorption and utilization in spring maize, and to provide scientific evidence and technical guidance for optimizing fertilization strategies to achieve high yield and efficient nitrogen utilization in spring maize cultivation in eastern Sichuan. A field experiment was conducted to assess the changes in yield, nitrogen absorption, and nitrogen utilization under seven nitrogen management treatments. The treatments included no nitrogen application (CK), conventional nitrogen application (ON) and CRN fertilizer applied at 0% (NR0), 25% (NR25), 50% (NR50), 75% (NR75) and 100% (NR100) of the conventional nitrogen rate, with a 25% reduction in total nitrogen input in eastern Sichuan. The results showed that CRN fertilizer significantly enhanced both dry matter and nitrogen accumulation in maize. At the tasseling and silking stage, with the increase of the proportion of CRN fertilizer, the rates of dry matter and nitrogen accumulation initially promoted, then reduced. After the filling stage, a CRN proportion of ≥50% was most effective for both dry matter and nitrogen accumulation, with NR50 showing the highest values. CRN fertilizer also promoted the redistribution of nitrogen from vegetative organs to grains. However, as the proportion of CRN fertilizer increased, the contribution of nitrogen from vegetative organs to grains decreased. Furthermore, CRN fertilizer improved the yield factor composition and maize yield, with NR50 showing the most significant increase. Agronomic efficiency and partial factor productivity of CRN fertilizer were higher than those of conventional nitrogen application. NUE of NR50, NR75 and NR100 was greater than that of ON. In conclusion, a 25% reduction in total nitrogen application, combined with 50% CRN fertilizer and 50% urea, was the optimal fertilization strategy for improving nitrogen absorption, enhancing dry matter and nitrogen accumulation, and increasing both yield and nitrogen use efficiency in spring maize in eastern Sichuan.

To screen the excellent maize varieties suitable for planting in Lingbi County, Anhui province, 34 new corn varieties, such as Kangnongyu 8009, Zhongyu 303 and Siyougu No. 5, were used as experimental materials, growth period and disease resistance were recorded, and agronomic traits, such as plant height, yield and yield traits, such as 100 grain weight were measured and evaluated comprehensively. The results showed that the growth period of each variety was 99-105 days. In terms of resistance, stem rot and small spot of all varieties were grade 1, and some varieties were susceptible to rust and sheath blight. In terms of agronomic traits, plant height was 206.4-267.3 cm, ear position 67.2-103.4 cm, ear diameter 4.3-5.0 cm, row number of spike 12.4-17.6 rows, row number 29.0-36.1 grains, seed yield 88.0%-91.5%. In terms of yield and yield traits, the effective panicle was 67 500 panicles /hm², the 100 grain weight was 25.43-36.42 g, the number of grains per panicle was 378.96-603.94 grains, and the yield was 7 240.50-10 062.75 kg/hm². The 5 varieties of Longding 728, Pudan 12, Jiaxi 100, Weike 985 and Denghai 1875 had the best comprehensive performance and were suitable for planting in the study area and related areas.

Literature review combined with practice was used to analyze the advantages of promoting corn planting techniques, the practical problems encountered in the process were explored of promoting planting techniques, and optimization measures were proposed. The promotion of corn planting techniques is beneficial for improving corn yield, optimizing quality, and increasing farmers’ income; in the process of techniques promotion, there are mainly problems such as unsmooth promotion channels, lack of personalized services, and low acceptance of new technologies by farmers. Based on the existing practical problems, propose to improve the corn planting technology promotion service system, provide personalized technical services for corn planting, and enhance farmers’ awareness and understanding of new technologies and other agricultural technology promotion strategies. The promotion of corn planting techniques is of great significance for the sustainable development of corn planting industry. This article provides a reference for further promotion and application of corn planting techniques in relevant regions.

The corn industry in Huangshan City of Anhui Province had made some achievements in recent years, and the area and output had grown year by year. This article introduces the basic situation of the corn industry from 5 aspects: the natural conditions, the corn planting area and output of corn over the years, the corn planting area and output of corn in each district and county, the promotion of varieties and the promotion of technology. It analyzes the main problems in 5 aspects of natural conditions, planting level, scale level, socialized service level, and corn industry chain. Based on the above analysis, some strategies are put forward such as strengthening the construction of agricultural infrastructure, accelerating the introduction and promotion of new varieties，promoting green high-yield cultivation technology, cultivating social service organizations, strengthening the construction of regional public brands, and promoting the extension and supplement of industrial chain to provide a reference for the development of the corn industry in relevant regions.

To explore the effects of water-fertilizer integration technology on the characters and yield of close-planted corn, 4 treatments were set up in this experiment. Including high dense planting corn A with integrated water and fertilizer system for 4 times (T₁), high dense planting corn B with integrated water and fertilizer system for 4 times (T₂), high dense planting corn B with integrated water and fertilizer system for 4 times + chemical control at jointing stage for 1 time (T₃), and high dense planting corn B with integrated water and fertilizer system for 4 times without adding fertilizer + conventional fertilizer (CK). Temperature, agronomic traits such as plant height and green leaf rate, and economic characters such as number of grains per spike and weight of 100 grains were measured. The results showed that T₂ showed better agronomic traits, with higher plant height, ear position and leaf length and width. The green leaf rate, grain number per spike and unit yield of T₃ were significantly higher than those of other combinations, which were 93.25%, 565.8 grains per spike and 14 220 kg/hm², respectively. In conclusion, the application of water-fertilizer integration technology on close-planted corn can appropriately reduce fertilizer application, increase plant height, ear row number, row number and unit yield.

To promote the promotion and application of green prevention and control technology in the prevention and control of corn diseases and pests, the specific applications and prevention effects of agricultural prevention and control, physical prevention and control, biological prevention and control, and chemical prevention and control were studied by reviewing relevant literature and combining practice. The main measures for agricultural prevention and control include selecting corn varieties with strong adaptability, high-yield, and excellent quality; croping rotation with crops such as soybeans and wheat to reduce the occurrence of pests and diseases; utilizing the ecological complementarity between different crops, intercropping with crops such as potatoes and peanuts; reasonably controling the ratio of nitrogen, phosphorus, and potassium fertilizers, scientifically applying base and topdressing fertilizers to improve the stress resistance of corn; timely and moderate irrigation to maintain suitable soil moisture. Physical prevention and control mainly uses physical factors or mechanical equipment, such as insect-killing lamp and sticking traps, to attract and kill pests. Biological prevention and control mainly utilizes natural enemies and microbial agents for control. Chemical control is mainly applied in situations where diseases and pests are severe or biological control methods cannot effectively respond, through scientific and precise application of drugs to effectively control pests and diseases. The comprehensive application of green prevention and control technology can reduce the incidence of corn diseases and pests, improve yield and quality, it is an effective way to achieve sustainable corn production. This article provides references for achieving high-quality, efficient, and eco-friendly corn and other crops production.

Maize (Zea mays L.) is a monoecious grass species with separate male and female inflorescences which form the tassel and ear, respectively.  The mature ear inflorescences usually bear hundreds of grains, thus directly influence maize grain production and yield.  Here, we isolated a recessive maize mutant, tasselseed2016 (ts2016), which exhibits pleiotropic inflorescence defects and a reduction in grain yield.  These defects include loss of determinacy and identity in meristems and floral organs, as well as a lack of the lower floret abortion in maize ear, and the smaller grain size.  Using map-based cloning and allelic test, we identified and confirmed a microRNA gene MIR172e as the target gene controlling these related traits.  Furthermore, our evidence uncovered a new potential miR172e/ETHYLENE RESPONSIVE ELEMENT BINDING197 (EREB197) regulatory module which controls the abortion of lower floret in maize ear. Transcriptome analysis revealed that the mutation of MIR172e represses multiple biological processes, particularly the flower development and hormone-related pathways in maize ear.  Additionally, we found the mutation in the DNA sequence of MIR172e affects in RNA transcription, resulting in elongation blockage at the mutant site.  Our results reveal the function and molecular mechanism of MIR172e in maize inflorescences and grain yield, and this study deepens our knowledge of maize inflorescence development.

Foodstuff maize is an important part of the modern maize industry in Linzhi City, and its production and application are extremely wide. In order to find out the high yield and high efficiency planting methods, we used three sowing densities (6×10⁴, 9×10⁴ and 12×10⁴ plants/hm²), and set up three harvest times (1/3 milk-line, 2/3 milk-line and milk-line disappeared stages) under the sowing density of 9×10⁴ plants/ hm², to compare and analyze grain yield, bio-yield and other yield traits of three different maturity maize hybrids (very early maturity, early maturity and medium maturity). The results showed that the fertility period of maize of different maturity was extended when planted in Linzhi City. The yield potential of medium-maturing variety was higher than that of very early and early-maturing varieties. Because of the limited soil fertility in Linzhi City, the planting density should not be too high, and should be controlled within 6×10⁴ plants/hm² in mid-low yielding lands, and should not exceed 9×10⁴ plants/hm² in high yielding field. Due to the local temperature influence, the grain filling rate was slow. The grain maize should be harvested at the stage of the milk-line disappearance, while the best harvesting time for silage maize was at the stage of 1/3 milk-line. In Linzhi City habitat, variety maturity had the greatest effect on the yield of foodstuff maize, sowing density should not be too high, and harvesting time differed according to specific uses.

Maize (Zea mays L.) is an important food and silage crop with high production potential and economic benefits (Erenstein et al. 2022).  Understanding the maize yield potential can provide reliable theoretical and practical support for achieving breakthroughs in grain yield (Meng et al. 2013).  It was one of the effective ways to explore the grain yield potential based on the model on a national scale.

In China, maize was widely cultivated. The four major maize regions span from 21° to 53°N in latitude and 73° to 135°E in longitude and cover the most complex climatic conditions suitable for maize growing in the world (Xu et al. 2017).  The regional climate heterogeneity tends to induce ecological adaptability responses of maize, which can also lead to variations in the interregional adaptability of crop models (Abbas et al. 2023).  In addition, in the context of global climate change, crop production has been severely affected by extreme weather events, especially maize and wheat (Schmitt et al. 2022).  Clarifying the regional adaptability of the crop growth models is an important basis for analyzing the response of maize to climate change.

Nowadays, crop growth models have been increasingly developed and applied, which play a crucial role in regional simulation, future climate scenario simulation, optimization of cultivation measures, and assessment of meteorological disaster impacts.  Currently, the main crop models applied in China include AquaCrop, APSIM, and WOFOST models, most of them were mainly focused on wheat and rice and the application status varied with regions (Jin et al. 2016; Kheir et al. 2021).  The Hybrid-Maize model is a maize-specific process model developed on the studies of high-yielding maize in the United States, which has been tested and widely used in the United States and South Asia (Yang et al. 2004; Timsina et al. 2010).  It can simulate the maize grain yield potential in specific years and regions by inputting the required relevant parameters including meteorological data, the tested cultivars, and field management information (Yang et al. 2004).  Most importantly, it provides a basis for clearing the maize grain yield improvement space and technical approach to reduce the yield gap.  Currently, under the background of dense panting conditions to increase maize grain yield, the application of this model in China has gradually attracted attention.  However, previous studies on the Hybrid-Maize model were mainly limited to specific regions or sites and applied under low planting conditions (Liu et al. 2012; Meng et al. 2013; Hou et al. 2014).  There were few reports assessing its adaptability at large spatial scales and under dense planting conditions. The climatic conditions were diverse in different maize growing regions across China.  Therefore, it is crucial to evaluate the adaptability of models under dense planting conditions in different regions.  In this study, we evaluated the performance of the Hybrid-Maize model in the major maize growing regions of China based on field data at 22 experimental sites under high planting density (7.5×10⁴ plants ha^-1) during the period of 2011-2015.  The maize growing information and climatic conditions of the experimental sites were listed in the Appendix A.  The findings can provide a reference for the application of the Hybrid-Maize model under dense planting conditions in different regions of China.

The results of this study showed that the normalized root mean square error (NRMSE) were all below 30.0% and the index of agreement (D) were approached to 1, which indicated that the simulated yield was within an acceptable range (Fig. 1-A).  Particularly, the model showed the best adaptability in the NW (Northwestern maize growing region, NRMSE=9.8%).  A similar performance in the prediction of grain yield (NRMSE=7.1%) was observed in the United States under high density (Abimbola et al. 2022).  It was mainly that the Hybrid-Maize model was developed based on high-yielding fields in the United States, where the planting densities commonly exceed 7.5×10⁴ plants ha^-1 (Yang et al. 2004).  It was also shown that the average maize grain yield in the NW was significantly higher than that in the SW (Southwestern maize growing region), HHH (Huang-Huai-Hai maize growing region), and NM (Northern Spring maize growing region).  The average measured grain yield in the NW (18.2 Mg ha^-1) was higher than that in the SW (9.4 Mg ha^-1), HHH (11.0 Mg ha^-1), and NM (13.2 Mg ha^-1).

Aboveground biomass and harvest index (HI) are the bases for maize grain yield formation.  It was indicated that the model had better simulation effects in aboveground biomass with a lower NRMSE value in the NW (17.2%) than that of SW (24.8%), HHH (22.9%), and NM (26.2%) (Fig, 1-B).  The simulation accuracy of this model for aboveground biomass in the NM (NRMSE=26.2%) was similar to a previous study conducted in the Northeast region under sufficient irrigation conditions (NRMSE=24.4%) (Liu et al. 2012).  However, the performance of the model was slightly different in these growing stages with a similar trend in simulated accuracy (i.e., the jointing stage>silking stage>maturity stage) for these four regions.  As for the harvest index, it was shown that the Hybrid-Maize model perform well in the NM and HHH under dense planting conditions (Table 1).  The simulated HI for all regions with the trend of HHH>NM>NW>SW that differed from the spatial distribution (NW>SW>NM>HHH) in the previous study (Liu et al. 2020), which may be related to the overestimation of the HI in the HHH and NM and underestimation in the NW and SW by this model.  Therefore, further optimization in the HI is required for this model when applied across different regions.

The dynamic changes in leaf area index (LAI) are shown in Fig. 1-C.  There were significant differences in the performance of the Hybrid-Maize model between regions under dense planting conditions.  The performance of the model in simulating LAI was better in the HHH (NRMSE=28.8%) and NM (NRMSE=22.0%) than that in the NW (NRMSE=33.4%) and SW (NRMSE=44.2%).  Additionally, it was observed that the Hybrid-Maize model showed a good fitting degree in the jointing and mature stage period in most of these regions.  Overall, this simulated values were higher than the measured with an average overestimation of 37.0% for the whole growth season.  Specifically, the simulated values in the SW were on average 43.6% higher than the measured.  In the NM, the simulated values were on average 12.5% lower than the measured after silking.

In summary, the Hybrid-Maize model showed good adaptability in the simulation of grain yield and dynamic changes of aboveground biomass in the four major maize growing regions of China under moderate planting density conditions, especially in the NW and SW.  However, there was a significant underestimation of HI in the NW and SW.  Conversely, there was an overestimation of LAI in these regions.  Further evaluation of the model can be calibrated by adjusting the LAI and HI to refine the prediction of grain yield potential.  Overall, the Hybrid-Maize model can provide relatively acceptable simulation references in the HHH and NM for all parameters under dense planting conditions. 

Promoting the strip intercropping model of soybean and corn is one of the effective ways to improve soybean production capacity. The practice of strip intercropping of soybean and corn was based on in the Huaibei, Anhui Province, and its efficient cultivation techniques were summarized from the aspects of variety selection, planting model selection, seed treatment, and etc. In terms of variety selection, selecting soybean varieties with limited podding habits, shade tolerance, dense planting tolerance, high temperature tolerance, lodging resistance, disease resistance, and drought resistance; corn varieties with compact plant type, moderate height, high temperature tolerance, dense planting tolerance, ear rot tolerance, disease resistance, and suitable for machine harvesting. Selecting the planting model of 4 rows of corn and 6 rows of soybeans. Seed treatment including seed selection, sun drying, pesticide mixing or coating. Selecting 4 rows of corn seeders and 6 rows of soybean seeders for simultaneous fertilization and sowing. After sowing and before sprouting, timely sealing and weeding should be carried out. For plots with poor sealing and weeding effects, corn and soybean specific herbicides should be used for targeted isolation and weeding during the 1-2 compound leaf stage of soybeans and 4-5 leaf stage of corn. To meet the water and fertilizer supply needs during the corn bell mouth stage, soybean flowering and pod setting stage, and grain filling stage, the integrated technology of micro spray irrigation and fertilization is adopted for irrigation, topdressing, and foliar fertilization. Spraying control agents on 6-9 leaves of corn and early flowering stage of soybeans to control plant growth. Adhering to the principle of prevention first and combining prevention and control, and timely apply appropriate drugs to prevent and control diseases and pests such as soybean virus disease, aphid, corn stem rot disease, and Spodoptera frugiperda, etc. Choosing soybean varieties that are resistant to high temperature and heat damage, apply fertilizers reasonably, and water them in a timely manner to prevent soybean ‘disease greening’. Selecting varieties of corn that are resistant to high temperature and heat damage, water them in a timely manner, and use artificial pollination to prevent and control the impact of high temperature and heat damage on the tasseling and silk emergence stages of corn. Based on the maturity of soybeans and corn in the field, choose the method of harvesting first after maturity or harvesting with different machines simultaneously. This article provides references for further promotion and application of the soybean corn strip intercropping model in relevant regions.

The aim is to study the effects of different planting densities and planting ratios on biomass accumulation, nitrogen absorption, yield and economic benefits, and soil nutrient status of maize and soybean. Based on a field experiment, six treatments, including maize monoculture (M), soybean monoculture (S), maize/soybean 2:4 mode (I₁) [60000 maize plants/hm²+135000 soybean plants/hm² (D₁), 67500 maize plants/hm²+135000 soybean plants/hm² (D₂)], and maize/soybean 4:6 mode (I₂) [60000 maize plants/hm²+135000 soybean plants/hm² (D₁), 67500 maize plants/hm²+135000 soybean plants/hm² (D₂)], were designed. The results showed that maize/soybean planting pattern significantly decreased crop yield and biomass, compared to M and S, maize yield was decreased by 18.91%-25.45%, biomass was decreased by 12.62%-30.69%, soybean yield was decreased by 50.43%-56.79%, and biomass was decreased by 36.84%-46.61%. The biomass and yield of maize in I₁ were lower than that of I₂, while soybean showed the opposite trend. Under the same planting ratio, the maize yield of D₁ was significantly higher than that of D₂, while the soybean yield was not significantly different. Due to the difference of yield and input cost, the economic benefits of different planting patterns are different. Among them, the economic benefits of I₁D₁ were increased the most compared with M and S, which were 38.61% and 22.25%, respectively. In addition, different maize/soybean planting patterns could improve the soil chemical properties, especially the contents of soil alkali-hydrolyzed nitrogen and organic matter in maize soil. Compared with M, I₁D₁ significantly increased the contents of alkali-hydrolyzed nitrogen and organic matter by 14.17% and 16.61%, respectively. Overall, the maize/soybean 2:4 planting pattern combined with 60000 maize plants/hm²+135000 soybean plants/hm² is the optimal treatment in terms of improving crop yield and economic benefits of the system and improving soil nutrient status, etc. The research results have certain theoretical value for the application and promotion of maize/soybean combined planting pattern in Shandong Province.

【Objective】Husk is an important trait that affects the mechanical harvesting of maize grain, and identification of the genetic loci and candidate genes can provide theoretical basis for genetic improvement of maize husk traits. 【Method】To identify significantly associated single nucleotide polymorphisms (SNPs) and predict candidate genes for three husk traits, 251 maize inbred lines were used as plant materials and evaluated for husk number (HN), length (HL), and coverage (HC) in two environments. The genome-wide association study (GWAS) was conducted by multi-locus random-SNP-effect mixed linear model (mrMLM) with 32 853 SNPs across entire genome. 【Result】The three husk traits exhibited abundant variation among 251 maize inbred lines with 10.65%-40.60% of phenotypic variation coefficients. The variances of genotype, environment, and the genotype×environment interactions were significant at P<0.01 for each trait, and the broad-sense heritability for each trait was more than 80%. A total 92 SNPs significantly associated with three husk traits were identified in two environmental and best linear unbiased predictors (BLUP) across two environments values by GWAS. Among these SNPs, 35 SNPs were significantly associated with HN, and the phenotypic variance explained by single SNP ranged from 1.48% to 10.53%. 33 SNPs were significantly associated with HL, and the phenotypic variance explained by single SNP ranged from 1.61% to 21.69%. 24 SNPs were significantly associated with HC, and the phenotypic variance explained by single SNP ranged from 2.17% to 20.86%. However, none of SNP could be significantly associated with two husk traits. Five of 92 SNPs were stable, as they were repeatedly detected in two environments and BLUP, also they were novel loci for first reported in this study. Based on the five stable SNPs and qRT-PCR analysis for husk tissue of 17 maize inbred lines, three candidate genes (Zm00001d003850, Zm00001d033706 and Zm00001d025612) related to maize husk were screeded out, which encoded BOI-related E3 ubiquitin-protein ligase, GeBP transcription factor, and protein of unknown function, respectively. 【Conclusion】A total of 92 SNPs significantly associated with three husk traits were identified, including five stable SNPs. Three candidate genes were predicted that might be involved in maize husk growth and development.

【Objective】This study explored the effects of different mulching methods on the production of photosynthetic substances and water use of maize under the intercropping mode of maize and soybean, aiming to determine the suitable mulching method for maize and soybean plantation in dryland agriculture in northern Shaanxi, so as to provide a basis for high-yield and efficient production of maize and soybean and ecological environment protection. 【Method】This study was conducted in irrigated land and nonirrigated land in 2022, using 'Zhonghuang 30' soybean and 'Xianyu 335' maize as materials. The two-factor complete randomized design was carried out, and the control group combined single crop (maize “M”, soybean “S”) and film mulching (bare land, interbrane “J”), and the test group combined intercropping crop (maize “M”, soybean “S”) and film mulching (bare land, interbrane “J” and whole film “Q”), with a total of 13 treatment groups. The characteristics changes of growth, photosynthesis, and water use efficiency of intercropped maize under different mulching methods were studied. 【Result】 (1) From jointing to silking stage, the growth space of intercropped maize was limited, resulting in a disadvantage in aboveground biomass of intercropped maize compared with monoculture. The biomass during the jointing stage of S/MQ, SQ/MJ, and SQ/MQ was 5.1%, 6.3%, and 1.7% higher than that of monoculture M, respectively; under intercropping, SJ/MJ maize plants had the fastest growth rate and a sharp increase in growth. SQ/MQ S/M, S/MJ, SQ/MJ, and SJ/M in dry land had a better promoting effect on the photosynthetic products of maize during the silking stage, and the aboveground biomass was 0.6%-105.9% higher than that of monoculture M. (2) To some extent, intercropping and mulching treatments improved the photosynthetic characteristics of maize, and the net photosynthetic rate (Pn) content of paddy maize. There was a certain degree of positive relationship between stomatal conductance (Gs), cellular CO₂ concentration (Ci) and transpiration rate (Tr). The photosynthetic parameters of SQ/MJ and SJ/MQ were relatively high, while SJ/M and SQ/MQ were lower than non film coated S/M; there was a weak negative correlation between Pn and Ci in dryland maize, and the effect of maize mulching was not significant among different treatments. The Gs of intercropping treatment was 5.7% -38.1% lower than that of monoculture M, and Tr was also reduced by 5.6% -25.6%. Only the Pn of SJ/M and SQ/M, as well as the Ci of SQ/MJ and S/M, were higher than monoculture M. (3) The intercropping film mulching had a significant impact on water use efficiency (WUE). The WUE of the intercropping treatment was 41.1% -74.0% higher than that of monoculture M, among which SJ/M, S/M and S/MJ were relatively high; among all treatments in arid land, SQ/MJ had the highest WUE (19.04 kg∙mm^-1∙hm^-2), followed by SJ/MJ (17.07 kg∙mm^-1∙hm^-2), and the WUE of SJ/M and SQ/M was significantly lower than that of monoculture M by 26.7% and 20.6%, respectively. (4) Compared with monoculture M, intercropping S/MJ between irrigated land and dry land SJ/M and SJ/MJ maize increased yields by 76.8%, 73.0%, and 72.3%, respectively, while soybean yield reduction was relatively less among all intercropping treatments, demonstrating higher economic benefits; dry land intercropping SJ/MJ and SJ/MQ maize increased production by 17.1% and 23.5%, respectively, while economic benefits decreased by 17.5% and 22.8%, respectively. 【Conclusion】Compared with single cropping M, SJ/MJ model improved the photosynthetic performance, biomass, and yield of maize in irrigated land, and improved system economic benefit and promoted water use efficiency. In dry land, through the complementary effect and resource allocation in the intercropping system, it maintained maize yield and improved water use efficiency, but the increase of total input in agricultural materials reduced the economic feasibility. Therefore, in the dryland agriculture of Northern Shaanxi, the intercropping planting pattern of maize with degradable film and soybeans with degradable film was recommended for both irrigated land and moderately irrigated dry farm, aiming to enhance water use efficiency, increase production and profitability, and promote sustainable ecological agriculture development.

This study is dedicated to the development of iron- and zinc-rich high folate maize (Fe ≥ 40 mg/kg, Zn ≥ 40 mg/kg, folate ≥ 150 μg/100 g), to improve the utilization rate of folate, and to prolong the shelf-life of freshly-eaten iron- and zinc-rich high folate maize. Five groups of iron- and zinc-treated groups with different concentrations and one group of clear water control group were set up, and the foliar spraying of iron and zinc mixed micronutrient fertilizer was carried out by unmanned aerial vehicles to obtain iron- and zinc-rich high folate maize. Different processing techniques were adopted to treat the obtained high folate maize to analyze the changes of folate content in the iron- and zinc-rich high folate maize under different processing and storage conditions, and to screen out the optimal processing and storage methods. Foliar spraying of iron and zinc mixed micronutrient fertilizer on high folate maize during the growth period significantly increased the iron and zinc content in the kernels, achieving the effect of iron and zinc nutrient fortification. The rate of folate loss during processing of vacuum-packed fresh maize was 11.97%, and the rate of folate loss during processing of vacuum-packed instant maize was 23.36%. Combined with the loss rate of folic acid in different processes and the changes of folic acid content under different storage conditions, the best effect of vacuum-packed instant maize was achieved by storing it at 4℃ for 60 d.

In order to study the influence of maize-peanut intercropping on crop and soil characteristics, this paper sets up the root separation test of corn and peanut potted plants to study the influence of maize and peanut intercropping on crop agronomic traits, physiological activities, soil microorganisms, soil enzyme activity and soil rapid nutrients. The results showed that maize-peanut intercropping affected the morphological and physiological indexes of crops. Plant height and relative chlorophyll content of peanut were increased by 71.4% and 11.3%, but root length, root weight and leaf weight were not significantly affected. Plant height, leaf fresh weight and root length of maize were increased by 43.9%, 122% and 45.6%, respectively. But there was no significant effect on the relative content of chlorophyll. Maize-peanut intercropping improved plant stress resistance, increased SOD and POD activities of peanut leaves by 66.7% and 129%, and decreased MDA content of peanut roots by 19.8%, respectively. The activities of SOD in leaves and roots of maize were increased by 39.9% and 17.0%, respectively, while MDA content in roots decreased by 61%. Maize-peanut intercropping changed soil available nutrient content, decreased peanut soil available N by 79.5%, but increased soil available P by 11.5%, and had no effect on soil available K content. It had no effect on maize soil available N and K, but decreased soil available P by 9.4%. Maize-peanut intercropping affected soil biological characteristics and increased soil enzyme activities, especially the alkaline phosphates activity. The soil alkaline phosphates activity in peanut and maize fields increased by 122% and 330%, respectively. The Maize-peanut intercropping could improve soil microenvironment and physiological activities of leaves and roots in seedling stage.

Based on the practical production and cultivation, the reasons for the formation of poorly sturdy corn cob and multiple ears were summarized and analyzed by referring to relevant literature, corresponding countermeasures were proposed, and the research direction was prospected. The main reasons for the formation of poorly sturdy corn cob and multiple ears included genetic factors of the variety, external environmental factors (high temperature and drought, cloudy and rainy), and cultivation management factors (sowing date, density, pest control, disease and insect pests, and pesticide application). By selecting stress resistant varieties, and carrying out field management such as reasonable fertilization, timely weeding, soil loosening, and timely watering, the stress resistance of corn can be improved, and poor ear development caused by improper management can be avoided. The next step of research will utilize modern technologies such as gene editing to analyze the mechanism of poorly sturdy corn cob and multiple ears formation; explore new agronomic measures such as foliar fertilization to improve maize yield and quality. This paper provides references for improving corn yield and promoting the healthy development of related industries.

The aim was to explore the regulation mechanism of different coupling ratio of irrigation and nitrogen fertilizer application on photosynthesis, transpiration rate, chlorophyll value, dry matter accumulation characteristic and yield of maize. In this research, using the corn variety of ‘Yuyu 22’ as research material, a split plot design field experiment was carried out in dryland areas of Gansu Province in 2022. Three irrigation application amount treatments of 3150 m³/hm² (W₁), 3825 m³/hm² (W₂) and 4500 m³/hm² (W₃) were set as the main plot, and three nitrogen application amount treatments of 0 (N₀), 272 kg/hm² (N₁) and 320 kg/hm² (N₂) were set as the split plot. Photosynthetic rate, transpiration rate, chlorophyll value, dry matter accumulation characteristic and yield at the growth period of maize were determined. The results showed that under a reduction of 15% in irrigation amount during growth, compared with the W₂N₀ and W₂N₂ treatments, the photosynthetic rate, transpiration rate and chlorophyll value under the W₂N₁ treatment were increased by 30.91%, 13.53% and 39.78%, 26.46% and 32.33%, 9.21%, respectively. The maximum growth rate of dry matter in W₂N₁ treatment was 7.5 and 3.7 days later than that in W₂N₀ and W₂N₂ treatments, respectively. The Vmax of W₂N₁ treatment was 11.25% and 4.24% higher than that of W₂N₀ and W₂N₂ treatment, respectively. Compared with W₂N₀ and W₂N₂ treatments, the biological yield and grain yield of maize with the W₂N₁ treatment were increased by 29.97%, 5.15% and 48.61%, 10.78%, respectively. The conclusion showed that the treatment with application coupling of irrigation and nitrogen (i.e. reduction of 15% irrigation amount during growth with 3825 m³/hm² and reduction of 15% N application amount with 272 kg/hm² at growth stage) could be considered as the best cultivation pattern management, which could provide technical guidance for further exploring for water-saving and fertilizer-saving and high yield and efficient cultivation of agriculture in the dryland areas.

The fall armyworm (Spodoptera frugiperda) is an invasive species and a destructive pest of maize, which significantly impacts native species and communities via complex mechanisms like competition for resources. However, the interaction between S. frugiperda and local pests remains unclear. In this study, we determined that Oriental armyworm (Mythimna separata) females with different mating status displayed different approach-avoidance behaviors towards maize which was damaged by S. frugiperda larvae. The virgin M. separata females were repelled, while the mated females were attracted by the S. frugiperda-damaged maize. To further understand the olfactory mechanism of this phenomenon, seven volatiles induced by S. frugiperda in maize were characterized by gas chromatography and mass spectrometry (GC-MS), including trans-2-hexenal, linalool, trans-β-farnesene, cis-3-hexenyl acetate, β-caryophyllene, trans-α-bergamotene, and isopentyl acetate. Additionally, electrophysiological and behavioral assays of the seven compounds were performed using both virgin and mated females of M. separata. We determined that virgin and mated females displayed different responses to the HIPV compounds. Trans-β-farnesene was the core compound for repelling virgin females, and trans-2-hexenal was the key attractant for oviposition in mated female M. separata individuals. These findings help our comprehension of the relationships between maize pests and offer new possibilities for controlling them by olfactory-based strategies. 

【Objective】The objective of this study is to optimize the classification and discriminant method of maize heterotic groups, and provide guidance and reference for maize breeding practices.【Method】Solid-phase chips were used to genotype 60 waxy maize inbred lines, and high-quality SNP markers with different density were obtained through quality control. Population structure analysis and genetic distance clustering were used to classify the 60 waxy maize inbred lines into different groups, and the differences between different classification methods were compared. On this basis, random forest and support vector machine methods were used to sample and discriminate the results of different classification methods. Five-fold cross-validation was used for sampling, and the prediction accuracy of maize group classification based on different classification methods was compared.【Result】Using different quality control standards, 11 431 and 4 022 molecular markers were obtained, respectively. Based on these two molecular marker densities, 60 materials were divided into 5 and 4 clusters, respectively. When using 11 431 SNP markers, the population structure analysis and genetic distance clustering results showed that the intra-cluster sample consistency was 63.33%. When using 4 022 SNP markers for clustering, the intra-cluster sample consistency was 90.00%. The prediction accuracy results for discriminating maize inbred line clusters showed that the average prediction accuracy (91.43%) of Random Forest and Support Vector Machine using 4 022 markers were higher than that of 11 431 markers (86.25%). Among them, the highest prediction accuracy was achieved by Random Forest using 4 022 markers, with a prediction accuracy of 94.17%.【Conclusion】Clustering analysis ultimately divided 60 waxy maize inbred lines into 4 clusters. Sampling and cross-validation results using Random Forest and Support Vector Machine for cluster classification showed that Random Forest achieved higher prediction accuracy than Support Vector Machine.

【Objective】Based on the long-term experiment in the North China Plain (NCP), the differences in soil nutrient and aggregate nutrient distribution between diversified crops and wheat-maize rotation systems were investigated. Additionally, it provided a comprehensive evaluation of soil quality indices (SQI), offering a scientific basis for enhancing soil quality and productivity in the NCP. 【Method】Four diversified crop rotation systems were evaluated, including spring sweet potato-winter wheat-summer maize (Psw-WM), spring peanut-winter wheat-summer maize (Pns-WM), spring sorghum-winter wheat-summer maize (Ps-WM), with winter wheat-summer maize (WM-WM) serving as the control. The soil samples from the 0-40 cm depth were collected during the second rotation in 2022, at the flowering and harvesting stages of winter wheat. The soil enzymes activities, aggregate stability, organic matter, and concentrations of nitrogen, phosphorus, and potassium in soil and aggregates of different sizes (>2.00 mm, 0.50-2.00 mm, 0.25-0.50 mm, and <0.25 mm) were assessed. The SQI for each crop rotation system was then comprehensively evaluated. 【Result】Compared with WM-WM, the three other crop rotations increased soil inorganic nitrogen content. Psw-WM significantly enhanced organic matter in the 0-20 cm layer, total nitrogen in soil aggregates (>2.00 mm, 0-10 cm), and organic matter in soil aggregates (>2.00 mm and 0.50-2.00 mm, 0-10 cm), which also increased cellulase, catalase, and alkaline protease activities. Pns-WM improved organic matter in the 20-40 cm layer and available potassium in soil aggregates (0.25-0.50 mm and >2.00 mm, 10-20 cm), as well as organic matter in soil aggregates (0-10 cm, >2.00 mm and 10-20 cm, >0.50 mm), which also increased sucrase, urease, and alkaline protease activities. Psw-WM improved the stability of 0-10 cm soil aggregates, while Pns-WM improved the stability of 0-30 cm soil aggregates. Both Pns-WM and Psw-WM significantly improved the SQI, with Pns-WM showing a higher improvement than Psw-WM. The path analysis revealed that the average weight diameter (MWD) of aggregates was a direct and significant affecting SQI. It also had a significant indirect positive effect on SQI by influencing inorganic nitrogen. Additionally, the increased organic matter led to a higher proportion of large aggregates, which significantly affected SQI indirectly. 【Conclusion】Legume (peanut) and root crop (sweet potato) rotations with wheat-maize rotations could significantly improve soil quality and enhance the soil nutrient supply capacity in the NCP.

To establish a solid theoretical foundation for the efficient management of insect pests in corn crops, practical plant protection strategies that reduce the amount of pesticides should be explored. A study was conducted to investigate the occurrence of Spodoptera frugiperda on maize in the mountainous area of Mengga Town, Mangshi City, Dehong Prefecture, Yunnan Province. Two types of pesticides, 5% emamectin benzoate and 15% indoxacarb, were tested on Spodoptera frugiperda in corn fields using plant protection drones and knapsack electric sprayers. Spodoptera frugiperda larvae can cause damage in the whole growth period of maize, and the infestation rate, damage index, number of insects per 100 plants, and the proportion of different insect ages in different growth stages of maize are significant different, and Spodoptera frugiperda is the most harmful in the big bell stage of maize. Two different methods of applying 5% emamectin benzoate and 15% indoxacarb had a significant impact on the incidence of Spodoptera frugiperda in maize fields. The damage rate and index of maize also showed a significant decrease between 3 to 14 days after application. There was no significant difference in the relative control efficacy of the same pesticide against Spodoptera frugiperda under two different methods. Still, the use of plant protection drones pesticide application had the advantages of labor-saving, time-saving, and pesticide-saving. Spodoptera frugiperda control had a positive effect on increasing the production of maize in the yield, and the experimental treatments results showed a significant increase in yield of the test variety 'Yunrui 62', with 25.28% to 28.93% production increase compared to the control treatment. In total, it is recommended to use UAVs equipped with anti-spray technology to protect plants during large-scale Spodoptera frugiperda control. Additionally, it's important to conduct thorough investigations and implement field management practices to prevent corn insect infestations, which are crucial for achieving high and stable crop yields. It's important to focus on integrating, demonstrating, and promoting the use of this technology in the future.

To analyze the utilization rate of nitrogen, phosphorus and potassium fertilizer in corn planting in Yanyuan, promote scientific fertilization to increase efficiency, and promote the protection and quality improvement of cultivated land, we set up treatments of no fertilizer, no nitrogen, no phosphorus, no potassium and NPK full fertilizer to carry out the utilization rate analysis of NPK fertilizer for corn. The results indicated that stem diameter, ear height, number of grains per ear and 1000-grain weight of NPK fertilizer treatment were higher than those of other treatments, except that plant height was lower than that of no potassium; the grain yield and stem and leaf yield were also the highest, which were 12.07 t/hm² and 13.55 t/hm², respectively. The order from high to low was full fertilizer zone (T₅) > potassium-free zone (T₄) > phosphorus free zone (T₃) > nitrogen free zone (T₂) > fertilizer free zone (T₁). The yield to investment ratio of NPK fertilizer area was the lowest (4.73), but the economic benefit was the highest. The utilization rates of N, P and K in the experimental field were from high to low as K > N > P, and the utilization rates were 56.61%, 43.14% and 9.55%, respectively. Therefore, the composite fertilizer containing nitrogen, phosphorus and potassium should be selected for corn production in Yanyuan, and the content of potassium and nitrogen should be higher than that of phosphorus. At the same time, we should increase the application of organic fertilizer and plant green fertilizer to improve the ecological environment and improve the quality of crops.

In order to analyze the agronomic traits, yield and yield composition of machine-harvested maize under different density treatments, machine-harvested maize ‘Ludan 608’ was used as the material. Five planting densities of 60000 plants /hm² (D₁), 69000 plants /hm² (D₂), 75000 plants /hm² (D₃), 82500 plants /hm² (D₄) and 90000 plants /hm² (D₅) were set to analyze their agronomic traits and yield. The results showed that plant height, ear height, lodging rate and bare plant rate increased with the increase of planting density, while double ear rate decreased. The highest maize yield was 11231.31 kg/hm² with the planting density of 82500 plants /hm². The LAI increased with the increase in planting density. The accumulation of dry matter in maize at both individual and population levels showed an ‘S-shaped’ growth curve of ‘slow-fast-slow’. The dry matter amount of single plant decreased with the increase in planting density. In the range of D₁-D₄, dry matter amount of population increased with the increase of planting density. And it began to decrease when planting density was more than D₄.

The study aims to explore the effects of nitrogen fertilizer and organic fertilizer combination on photosynthesis, dry matter accumulation, nitrogen use efficiency and yield of maize during the growth period. In this research, the cultivar ‘Woyu No.3’ was applied as research material. A split plot field experiment was conducted from 2022 to 2023 in Hexi Oasis Irrigation Area of Gansu Province. Four nitrogen fertilizer applications, i.e. without N application (N₀, CK), traditional N fertilizer application (N₁), 15% N fertilizer reduction (N₂) and 30% N fertilizer reduction (N₃), were set as the main plot, and three organic fertilizer applications, namely 3.5×10³ (O₁), 3.0×10³ (O₂) and 2.5×10³ (O₃) kg/hm², were used as the split plot. Photosynthetic, chlorophyll relative content, dry matter accumulation, nitrogen use efficiency and yield were determined. The result showed that, under the level of same nitrogen application in growth stages of maize, compared with the N₂O₁ and N₂O₃ treatments, the photosynthetic rate and transpiration rate and stomatal conductance under the N₂O₂ treatments were increased by 17.91%, 10.59% and 19.13%, 18.46% and 20.13%, 26.62%. Compared with the N₂O₁ and N₂O₃ treatments, the chlorophyll value and V_max and biological yield under the N₂O₂ treatments were increased by 18.73%, 9.77% and 13.79%, 17.84% and 7.14%, 6.78%. Compared with the N₂O₁ and N₂O₃ treatments, the grain yields and nitrogen use efficiency under the N₂O₂ treatments were increased by 18.77%, 20.14% and 15.68%, 8.02%. In summary, in the Hexi Oasis Irrigation Area with resource shortage, the reduction of N fertilizer by 15 % (306 kg/hm², N₂) combined with organic fertilizer (3000.00 kg/hm², O₂) could replace part of N fertilizer, which had high nutrient supply potential and the best effect on maize yield stability.

In order to study the changes of germination index and physiological index of maize under PEG simulated drought stress, 20% PEG-6000 was set up for drought treatment. The germination rate, germination potential, germination index, radicle length, chlorophyll value (SPAD), superoxide dismutase (SOD) activity and malondialdehyde (MDA) content of maize at germination stage were measured, and the drought resistance of different varieties was evaluated by membership function method. The results showed that compared with CK, the germination rate, germination potential, germination index and radicle length of each maize variety decreased under drought stress, the chlorophyll value and SOD activity decreased, and the MDA content increased. The average value of the membership function of ‘Xinnong 008’ was greater than 0.7, which was a strong drought-resistant variety. The average value of membership function of ‘Zhongyu No.9’, ‘Zhongyu No.1’ and ‘Woyu No.3’ was less than 0.4, which belonged to weak drought-resistant varieties.

In order to study the separation characteristics of plant traits in maize, ten maize inbred lines from different sources were selected for cross-mating, and two 8-parent hybrid F₁ segregated populations A and B were obtained. The phenotype of five plant traits of the segregated populations was identified, and the correlation analysis and path analysis between plant traits were carried out. The results showed that the variation coefficient of plant height in two segregating populations was large, and the coefficient of variation was 10.34% and 10.54%. Correlation analysis showed that the plant height showed extremely significant positive correlation with ear height, tassel length and average length of internode above ear, and tassel length showed extremely significant positive correlation with average length of internode above ear in two segregated populations. But the correlation between other plant traits of the two populations was not completely consistent. The path analysis showed that the ear height, tassel length and average length of internode above ear had significant positive direct effect on plant height. The tassel length had a large positive indirect effect on plant height through the average length of internode above ear. This study analyzed the relationship between plant traits, which could provide reference for genetic improvement of plant traits in maize.

The causes of common diseases and pests in corn planting process were summarized and analyzed, and corresponding control measures according to the types of common diseases and pests were put forward. In the process of corn production, soil nutrient deficiency and light insufficiency, excessive water and other factors will lead to the occurrence of diseases and insect pests. The common diseases in corn production included Puccinia sorghi, Bipolaris maydis, Exserohilum turcicum, Sphacelotheca reiliana; common pests included Spodoptera frugiperda, Ostrinis furnacalis and Rhopalosiphum maidis. Based on the occurrence characteristics of diseases and pests, the rule and the way of transmission were put forward, such as cleaning up diseased plants and weeds, selecting disease-resistant varieties and applying chemical agents, biological bacteria and other pest control measures. The research results provides references for the control of diseases and pests in large-scale corn production.