针对玉米脱粒离散元仿真中果穗模型难以表征籽粒分离和芯轴破碎的问题，该研究构建了玉米果穗聚合体离散元模型并进行脱粒仿真验证。基于玉米芯轴3层结构采用分层建模与网格划分方法建立玉米芯轴离散元模型，结合Plackett-Burman试验、最陡爬坡试验、Box-Behnken试验和仿真弯曲试验标定粘结参数；以马齿型玉米籽粒为原型，采用五球粘结的籽粒-芯轴连接方式建立玉米果穗聚合体离散元模型，仿真标定籽粒与芯轴的连接力；最后模拟梯形杆齿、圆头钉齿和纹杆块3种脱粒分离机构的玉米脱粒进程。结果表明：玉米芯轴弯曲破坏力和弯曲刚度仿真结果与实测平均值的相对误差分别为-0.12%和-0.14%，籽粒果柄轴向压缩力和径向压缩力仿真结果与实测平均值的偏差分别为-1.8和2.46 N,3种脱粒分离机构脱粒段仿真区域内籽粒平均法向接触力依次为12.50、12.32和8.03 N,3种脱粒元件对籽粒平均法向接触力的递减趋势与台架试验的籽粒破碎率变化一致，根据籽粒与脱粒元件接触合力的累积频率曲线确定籽粒破碎率的临界接触合力为550 N，仿真未脱净率依次为0.15%、0.37%、0.35%，较台架试验结果分别偏小0.07、偏高0.04和偏小0.25个百分点，沿滚筒轴向籽粒质量分布百分比曲线均表现为正偏态单峰分布，脱粒仿真试验的曲线峰值分别比台架试验高1.03、1.86和0.85个百分点，两者脱粒质量相近。该玉米果穗聚合体离散元模型参数标定准确，能够准确反映籽粒和芯轴的力学特性差异，可还原玉米脱粒分离过程，为后续脱粒分离机构的优化提供参考依据。

The effects of green manure on soil microorganisms and physicochemical properties, corn yield, and quality were summarized and analyzed, based on relevant literature and work practice. By rolling or intercropping green manure crops, the organic matter and microbial content in the soil can be increased, its physical and chemical properties can be improved, and its water and fertilizer retention capacity can be enhanced; The application of green manure can promote the growth of corn, increase its grain yield, and also have a certain promoting effect on its quality traits such as amino acids and proteins. Different types of green manure have different effects on soil physical and chemical properties and corn growth. Suitable green manure crops should be selected based on soil fertility conditions, production goals, etc. to improve the yield and quality of corn.

The aim was to evaluate lodging resistance of germplasm in maize, and then breed maize hybrids with strong lodging resistance. In this study, four maize hybrids which were currently promoted in production were used as materials. Through measuring the lodging resistance related traits, mid-parent heterosis and over-parent heterosis of related traits were calculated. The results showed that there were significant or extremely significant differences in crushing strength, pushing strength and stem strength among different varieties, 'Shuoyu 172' had higher crushing strength and stem strength, and 'Shuoyu 173' had higher pushing strength. Compared with different lodging resistant related traits, mid-parent heterosis and over-parent heterosis of 5^th internode length, stem diameter, plant height, ear height, and tassel branch number of 3^rd, 4^th and 5^th internode were relatively higher, indicating that the heterosis of these traits was relatively strong. Compared with the different materials, the parents of 'Shuoyu 172', 'Zheng 58' and 'H7235', and the parents of 'Shuoyu 173', 'Z33-1' and 'H7875S', had strong heterosis in crushing strength, stalk strength, tassel branch number, tassel main axis length and angle of ear. The stem diameter plant height, ear height, ear leaf length and width of 3^rd, 4^th and 5^th internode between the parents of 'Baojing 186', 'Z33-1' and 'H7875A', and the parents of 'Zhengdan 958', 'Zheng 58' and 'Chang 7-2' had strong heterosis. Principal component analysis were used to evaluated lodging resistance of different varieties, the results showed that the lodging resistance of 'Shuoyu 172' was the strongest (Y: 1.401), followed by 'Shuoyu 173'. This study indicated that both of 'Shuoyu 172' and 'Shuoyu 173' had strong lodging resistance.

In order to study the impact of gale disasters on corn crops in high latitudes, based on the theory of natural disaster risk and combined with ArcGIS spatial analysis technology, this paper analyzed the risk factors of gale disasters in Heilongjiang Province, the environmental sensitivity of disaster, the exposure of disaster bearing bodies and the ability of disaster prevention and reduction, and carried out a comprehensive risk assessment. The research shows that the high incidence areas of corn gale disasters are concentrated in the southeast of Songnen Plain and the west of Sanjiang Plain. These areas have flat terrain, no large-scale vegetation coverage, high wind risk coefficient, large corn planting area and medium disaster prevention and mitigation ability. It is suggested that maize lodging damage could be prevented and controlled by giving priority to the selection of lodging-resistant varieties, sowing in warm and suitable climate, regularly reinforcing maize plants during planting, and taking measures such as mulching protection. The results provide a theoretical basis for the relevant departments to adjust the agricultural structure and formulate disaster prevention and mitigation countermeasures and measures.

To investigate the efficiency of Sedum alfredii in extracting heavy metals from farmland under intercropping systems, this study employed the technique of intercropping the Cd-hyperaccumulator Sedum alfredii with sweet corn to conduct experiments in moderately cadmium-contaminated farmland in South China. The results indicated that under the intercropping system, the yield of sweet corn increased, and the Cd content in the kernels significantly decreased by 8.3% compared to monoculture. Additionally, under the intercropping system, the biomass of Sedum alfredii increased by 16.5%, with Cd accumulation in the roots and shoots increasing by 8.8% and 3.6%, respectively. The enrichment coefficients improved by 15.7 and 6.6 units, respectively. After intercropping sweet corn with Sedum alfredii, the Cd content in the top soil significantly decreased. The experiment demonstrated that the phytoremediation model of intercropping Sedum alfredii with sweet corn not only allowed for the simultaneous remediation and production of polluted farmland but also enhanced the extraction efficiency of the hyperaccumulator plant. This approach presented a practical and green remediation technology for moderately heavy metal-contaminated farmland.

The aim was to explore the effects of different new urea on yield and nitrogen uptake and utilization of winter wheat-summer maize rotation system in the North China Plain, with a view to providing a theoretical basis for the application of new urea in practical production. Using common urea as a control, six new types of urea were applied for 5 consecutive years to measure the yield of wheat-maize rotation, analyze the effect of new urea on the composition of the yield, and at the same time, determine the nitrogen uptake of plants and seeds, and account for the nitrogen fertilizer agronomic efficiency, bioproductivity, and production benefits of the new types of urea. The results showed that compared to the ordinary urea, continuous application of the new urea all significantly increased the yield of wheat-maize rotation system (P<0.05), with the range of yield increase from 7.08% to 11.77%, of which 9.02% was increased by the loss-control urea in the wheat season, and 15.52% was increased by the zinc-containing urea in the maize season; there was no significant difference in nitrogen absorption and utilization of the new urea during the wheat season, while the average nitrogen fertilizer agronomic efficiency of loss-control urea fertilization and zinc containing urea in the corn season reached 9.49 kg/kg and 10.63 kg/kg, respectively. From the perspective of production efficiency, the net benefit of using loss-control urea in batches and zinc (manganese) containing urea was the highest. Under the conditions of this experiment, it was recommended to apply loss-control urea or zinc (manganese) containing urea in the winter wheat-summer corn rotation system in the North China.

【Objective】The physiological mechanism of starch accumulation and yield formation of spring maize in black soil under suitable nitrogen application was studied, in order to provide the theoretical basis for high yield and high efficiency cultivation technology of spring maize.【Method】Field experiments were conducted in the spring maize growing seasons of 2022 and 2023 in Gongzhuling City, Jilin Province, Jilin Academy of Agricultural Sciences. Five nitrogen application treatments were set up: no nitrogen (N0), 90 kg·hm^-2 (N90), 135 kg·hm^-2 (N135),180 kg·hm^-2 (N180), and 225 kg·hm^-2 (N225). The synthesis capacity of sucrose in the ear leaf and the activity of key enzymes in sucrose metabolism were measured to investigate the sucrose synthesis capacity of the ear leaf and grain starch synthesis capacity under different nitrogen application rates. The accumulation characteristics of total starch and its components in maize grain were fitted by Logistic equation to clarify the impact of nitrogen application rate on the dynamic of starch accumulation in maize grain and grain yield formation.【Result】(1) With the escalation of nitrogen application rates, the yield of spring maize exhibited an initial increase followed by a subsequent decrease. The average yields under N0, N90, N135, N180, and N225 treatments over two years were 8 992.90, 11 199.47, 12 126.78, 14 049.42, and 13 213.21 kg·hm^-2, respectively. Notably, the N180 treatment resulted in the highest yield. (2) The sucrose content, sucrose synthetase (SS) and sucrose phosphate synthetase (SPS) activities in ear leaves at 0, 12, 24, 36 and 48 days after flowering under N180 treatment were significantly higher than those under N0, N90 and N135 treatment, and there was no significant difference between N225 and N180 treatment. At 24, 36 and 48 days after flowering, the activity of soluble amylase (SSS) in grains treated under N180 was the highest, and the average SSS activity of grains under N0, N90, N135 and N225 was increased by 62.43%, 31.33%, 14.85% and 7.80%, respectively. (3) Logistic equation analysis showed that the accumulation rate and active accumulation period of total starch, branch chain and amylose in grains of each treatment first increased and then decreased with the increase of nitrogen application amount, and N180 treatment was the best. Compared with N0, N90, N135 and N225 treatments, the two-year average total starch accumulation rate and total starch accumulation active period under N180 treatment were 43.35%, 23.16%, 13.22%, 5.92% and 7.30%, 3.84%, 4.11%, 3.83%, respectively. When the average grain starch accumulation rate reached the maximum in two years, the grain starch accumulation amount was 12.90 g, and the total starch accumulation amount at each treatment maturity stage was 6 725.60, 8 510.17, 9 150.62, 10 387.35 and 9 604.04 kg·hm^-2, respectively. (4) Correlation analysis results showed that spring maize yield was significantly positively correlated with sucrose content, sucrose synthase activity, sucrose phosphate synthase activity, soluble starch synthase activity in grains, total starch accumulation, amylopectin accumulation and amylose accumulation in grains at ear position at filling stage. Sucrose content, sucrose synthetase activity, sucrose phosphate synthetase activity and soluble starch synthetase activity in grain were also significantly positively correlated with starch and its component accumulation in grain.【Conclusion】Under the treatment of 180 kg·hm^-2 nitrogen application, the spring maize during grain filling exhibited the highest activities of key sucrose metabolism enzymes in the ear sheath leaves, as well as the highest activity of starch synthesis enzymes in the soluble grains. Additionally, it showed the maximum rate of starch accumulation and longest period of active starch accumulation. Furthermore, this treatment resulted in the highest grain yield and starch accumulation, making it the optimal treatment under the experimental conditions.

【Objective】The purpose of this study was to determine the effects of nitrogen application amount on the yield composition, economic benefit of summer sowing intercropping crops and the yield of winter wheat. 【Method】From 2022 to 2023, the representative farmlands were selected in Yucheng City, Shandong Province, which was the main extension area of maize-soybean strip intercropping. Maize monoculture (Nitrogen application rate: 225 kg·hm^-2), soybean monoculture (Nitrogen application rate: 45 kg·hm^-2), maize-soybean intercropping with full nitrogen application (Nitrogen application rate: 270 kg·hm^-2), maize-soybean intercropping with reduced nitrogen application (Nitrogen application rate: 135 kg·hm^-2) were set up in summer sowing season, and the subsequent crops were planted with wheat without fertilizer treatment. The effects of different summer sowing treatments on photosynthetic characteristics, agronomic traits, economic benefits and yield of subsequent wheat were analyzed. 【Result】Both planting pattern and nitrogen application amount had significant effects on crop growth and development. Compared with maize monoculture, the chlorophyll content, P_n, G_s, C_i and T_r of maize leaves were significantly decreased by intercropping reduced nitrogen application (135 kg·hm^-2). However, the P_n, G_s and T_r of leaves of intercropping full nitrogen maize (270 kg·hm^-2) were significantly increased by 8.8%, 10% and 11.6%, respectively. Intercropping system resulted in decreased chlorophyll content of soybean, inhibited leaf P_n, G_s, and T_r. In terms of agronomic characteristics, stem length increased, pod number per plant decreased, and yield decreased by 65.1%-68.4%. There was no significant difference in the agronomic characteristics and yield of maize under the intercropping system with full nitrogen application, and the economic benefit was the highest under this system, reaching 22 607 yuan/hm², while the agronomic characteristics such as ear length, grain number per ear and hundred-grain weight of maize under reduced nitrogen application significantly decreased, and the yield decreased by 14.8%. However, in general, the land equivalent ratio of both maize and soybean treatments was also greater than 1. Economic benefit and nitrogen uptake were increased by 4.8%-11.5% and 19.7%-38% compared with monocrop. When winter wheat was not fertilized, the grain yield and crop nitrogen uptake of aftercrop winter wheat with full nitrogen application in summer sowing were higher than that under other treatments, and there was no significant difference between the yield of winter wheat with reduced nitrogen application between summer sowing seasons and that of winter wheat with summer sowing maize. 【Conclusion】Therefore, from the comprehensive analysis of agronomic characteristics, yield and economic benefits as well as the effects on aftercrop, the effect of total nitrogen application in intercropping was better than that of reduced nitrogen application in intercropping. However, considering the yield, economic and environmental benefits, the amount of nitrogen application in intercropping should be further optimized.

In order to provide theoretical basis, identification method and selection index for the identification and screening of low nitrogen tolerant maize varieties, the research reports on the influence of low nitrogen stress on maize growth and development, the material basis of low nitrogen tolerance and the selection of low nitrogen tolerant varieties in maize at home and abroad in the past 20 years were summarized. It was found that low nitrogen stress seriously affected the growth and development of maize roots and plants, and grain yield. However, different genotypes of maize showed great differences in morphological characteristics, physiological and biochemical characteristics, nitrogen utilization efficiency, and grain yield. Under low nitrogen stress, the low nitrogen tolerant genotype showed that the root system grew well, root-shoot ratio was larger, the root system vigor was stronger. Meanwhile, the changes in plant height and stem thickness were not obvious, while the ear leaf area was larger. It was higher for the content of soluble protein, soluble sugar, and amino acids in its root secretions as well as the contents of chlorophyll and nitrogen in ear leaf. Nitrate reductase and glutamine synthetase activity were stronger in the cells, and the ear was larger, grains per ear were much and 100-grain weight was higher, these genotypes could obtain the high grain yield. It was considered that under low nitrogen stress, the biomass of roots and plants was high, the root-shoot ratio and ear leaf area were large, the content of soluble protein and soluble sugar in root exudates, the content of chlorophyll and nitrogen in ear leaves were high, the activity of nitrate reductase and glutamine synthetase in cells was strong, the number of grains per ear was large, and the weight of 100 grains and the weight of grains per ear were high. The above information could be used as important indicators for selecting low nitrogen tolerant maize genotypes.

【Objective】Genetic improvement for efficient utilization of maize nutrients represents a crucial method to ensure national food security. Exploring quantitative trait locus (QTL) and related candidate genes of nitrogen use efficiency can provide a theoretical basis for improving the efficiency of nitrogen fertilizer in maize and cultivating high-yield and high-efficiency maize varieties. 【Method】In this study, QTL mapping analysis in one recombinant inbred line (RIL) population constructed by KA105 and KB024 was performed for grain yield under two different nitrogen treatments, including the derived traits partial factor productivity from applied nitrogen (PFPN), low nitrogen tolerance coefficient (LNTC) and nitrogen agronomic efficiency (NAE). Concurrently, integrating the seedling transcriptome data of the parent KA105 under nitrogen treatment, differentially expressed genes were identified, and candidate genes associated with maize nitrogen use efficiency were mined through co-expression analysis. Subsequently, the selected candidate genes were validated using qRT-PCR. 【Result】Through mapping analysis, a total of 36 QTLs distributed across different chromosomes were detected, explaining 1.63% to 17.26% of the phenotypic variation. Among these, eight major QTLs with a phenotypic variation explanation rate exceeding 10% were identified, along with seven genetically stable QTLs commonly identified across different traits or environments. Notably, qNNGYP1 located on chromosome 1 has been repeatedly detected in previous studies, with a phenotypic explanation rate of up to 11.73%. Additionally, other QTLs (qNNGYP1, qPFPN1) co-located in this interval across different environments, suggesting it as a focal region for further investigation. Combining transcriptome data of seedlings under low nitrogen stress, 39 differentially expressed genes within these QTL intervals were identified, and 6 key genes were identified through co-expression network prediction. The result of qRT-PCR indicated that the expression trends of the candidate genes under both nitrogen treatments were consistent with the transcriptome data. Specifically, GRMZM2G366873 was involved in the regulation of auxin homeostasis and may participate in maize responses to low nitrogen stress, drought stress, and boron stress through auxin signal transduction, also regulating ear length. GRMZM2G414192 was involved in the response of the photosynthetic system to low nitrogen stress and was regulated by brassinosteroids. GRMZM2G414043 was associated with maize grain length and biomass, while GRMZM2G040642 may be involved in the long-distance signal transduction of nitrogen. 【Conclusion】In summary, a total of 36 QTLs were identified, distributed across chromosomes 1, 4, 5, 7, 8, and 9, including eight major QTLs (PVE>10%). The candidate genes GRMZM2G366873, GRMZM2G414192, GRMZM2G414043, and GRMZM2G040642 were identified as potential genes for maize nitrogen efficiency.

【Objective】This study aimed to explore the underlying reasons for the reduction of maize photosynthesis under the high temperature and drought combined stress, so as to provide theoretical basis for alleviating the combined stress of high temperature and drought. 【Method】Maize cultivar “Denghai 605” was selected as the experimental material for this experiment. Two temperature levels were set, namely normal temperature control (30 ℃/22 ℃ for day (8:00-18:00)/ night (18:00- 8:00 the next day)) and high temperature treatment (38 ℃/28 ℃ for day/night). The two water conditions were normal water supply control (soil water content was 70%-80% of field capacity) and drought treatment (soil water content was set to 50%-60% of field capacity). There were four treatments in the experiment, including control (CK), high temperature stress (H), drought stress (D), high temperature and drought combined stress (HD), and the treatment began at VT stage (VT). The changes in leaf gas exchange parameters, photosystem Ⅱ (PSII) performance, key photosynthetic enzyme activity, plant biomass, and grain yield under different stress treatments were analyzed. 【Result】High temperature, drought and combined stress all led to the increase of chlorophyll fluorescence parameters, the ratio of a variable fluorescence F_K to F₀-F_J amplitude (W_K) and variable fluorescence F_J to F₀-F_J amplitude (V_J), and damaged the donor side and acceptor side of PSII. Compared with the control, PSII maximum quantum yield for primary photochemistry (φ_P0), the probability of captured excitons transferring electrons to other electron acceptors in the electron transfer chain beyond Q_A (Ψ₀), quantum yield for electron transport (φ_E0), quantum yield of energy dissipation (φ_D0), quantum yield for reduction of the end electron acceptors at the PSI acceptor side (φ_R0), and performance index based on absorption of light energy (PI_ABS) were significantly decreased, and the absorption and transfer of light energy were inhibited; absorbed photon flux per active PSII (ABS/RC), trapped energy flux per active PSII (TR₀/RC) and dissipated energy flux per active PSII (DI₀/RC) increased significantly, but the electron flux from Q_A^‒ to the PQ pool per active PSII (ET₀/RC) decreased significantly, which affected the energy distribution of reaction centers, reduced the number of PSII active reaction centers, and inhibited the performance of PSII. Combined stress could aggravate the inhibition of PSII performance by damaging the donor side, the acceptor side and the active reaction center. At the same time, the activities of ribose 1, 5-diphosphate carboxylase (Rubisco) and phosphoenolpyruvate carboxylase (PEPCase) decreased, which inhibited photosynthetic carbon assimilation. High temperature, drought, and combined stress reduced the net photosynthetic rate by reducing the performance of PSII and the activity of key photosynthetic enzymes. Compared with the control, the net photosynthetic rate of VT+5 d was reduced by 14.6%, 31.4%, and 39.9%, respectively. The decrease in photosynthetic rate inhibited the accumulation of biomass and its transport to grains. Under high temperature, drought, and combined stress, the grain yield decreased by 80.3%, 27.1%, and 84.0% than that under control, respectively. 【Conclusion】In summary, the combined stress of high temperature and drought mainly reduced net photosynthetic rate, hindered biomass, and reduced grain yield by inhibiting leaf PSII performance. The impact of combined stress on PSII performance and grain yield was greater than that of single stress under high temperature and drought.

【Objective】Reasonably increasing planting density combined with appropriate nitrogen (N) application rate is an important technical approach for increasing maize yield and resource use efficiency. Understanding the interactive effects of planting density and N rate on maize growth, evapotranspiration (ET) and water use efficiency (WUE) during the growing season, could provide a basis for improving its use efficiency when increasing planting density and controlling N input in maize production. 【Method】Field experiments were conducted during 2022 to 2023 in Jilin Province. Two maize cultivars, Liangyu 99 (LY99) and Demeiya 3 (DMY3), were used in this study. Three planting densities of 50 000, 70 000 and 90 000 plants/hm² and four N application rates of 0, 100, 200 and 300 kg N·hm^-2 were designed to investigate the effects of planting density and N application rate on grain yield and water productivity of different maize cultivars, as well as the dry matter (DM), soil water content, ET and WUE at various growth stages. 【Result】Planting density significantly affected DM and grain yield of maize, but the response trends varied between cultivars. Grain yields of LY99 with 70 000 plants/hm² was 11.1% and 18.3% higher than that with 50 000 and 90 000 plants/hm², respectively. The average yield of DMY3 planted with 70 000 plants/hm² and 90 000 plants/hm² was 10.5% and 9.3% higher than that of 50 000 plants/hm², respectively. Nitrogen fertilization significantly increased DM and grain yield of maize, and also showed significant interactive effects with cultivar or planting density. Compared with N0, grain yields of LY99 were increased by 38.0% to 60.7% under N1, and the yield increases for DMY3 were 24.4% to 38.2%. Notably, the yield responses to N rates were more pronounced for LY99 compared with DMY3. For both cultivars, the yield differences between low N rate and high N rate enlarged with increasing planting density, with LY99 showing a more distinct performance. The water consumption and utilization of maize plants were also significantly affected by planting density, N rate and their interaction. During the growing season, the total ET of DMY3 continually increased with increasing density, while that of LY99 showed the highest values with 70 000 plants/hm² among different densities. In each density condition, the ET of both cultivars increased with increasing N application rates. The WUE of maize plants showed complex responses to planting density and N rate at different growth stages, due to the varied annual precipitation and distribution patterns. The average increase of water productivity of LY99 under planting 50 000 and 70 000 plants/hm² was 8.6% and 10.4% compared with 90 000 plants/hm² respectively_. DMY3 had the highest water productivity when planting 70 000 plants/hm², which increased by 5.8% and 5.3% compared with 50 000 and 90 000 plants/hm², respectively. The water productivity showed different responses to N rate among the three densities. In general, the difference of nitrogen application under low density was small, but it increased significantly under medium and high density. Compared wtih DMY3, LY99 showed higher increases for water productivity when N fertilizer was applied under medium and high density conditions. The correlation analysis showed that interactive effects of planting density and N rate significantly affected maize yield and water productivity by influencing the water utilization at various growth stages. 【Conclusion】Planting density and N rate had significant interactive effects on maize yield and water utilization in the rain-fed region of Northeast China. The two maize cultivars used in this study could obtain high grain yield and water productivity under a moderately higher density of 70 000 plants/hm² combined with 200 kg N·hm^-2 rate.

The simple, practical and easy to popularize straw composting and fermentation technology was explored. The corn straw was used as the test material to test the temperature, putrefier and moisture affecting the fermentation of corn straw. Four treatments were set up, included treatment 1 film retting fermentation, treatment 2 film retting fermentation + putrefactive agent, treatment 3 film retting fermentation + putrefactive agent + water, treatment 4 direct retting fermentation，and each treatment was repeated three times. The temperature, height, weight and fermentation degree of straw pile were measured every one month, and the color changes were observed and recorded. The optimum fermentation conditions of corn straw were obtained by comprehensive evaluation. The results showed that the temperature, weight and fermentation degree of straw pile were in the order of treatment 3> treatment 2> treatment 1> treatment 4 from high to low. The height of the straw pile from low to high was treatment 3< treatment 2< treatment 1< treatment 4. The color depth of straw pile was in the order of treatment 3> treatment 2> treatment 1> treatment 4. It was concluded that the treatment 3 was the best for straw fermentation, using film, straw maturing agent and maintaining humidity at the same time, could make corn straw mature to the maximum extent and could obtain benefits certain economic in actual production.

To clarify the effects of different nitrogen fertilizer application rates and phased drought on maize growth and water and water-nitrogen utilization efficiency, in this study, ‘Denghai Super 2’ and ‘Zhengdan 958’ were used as experimental materials to study the controlling effects of drought at the jointing stage, flowering stage and filling stage under different nitrogen fertilizer application rates on maize dry matter accumulation and water and nitrogen utilization efficiency through a pot experiment. The results showed that various phased droughts treatments both reduced the dry matter weight of maize grains, and reduced water use efficiency and nitrogen fertilizer use efficiency of maize. Drought appeared at flowering stage of maize had the maximal effects on the dry matter accumulation of grains, followed by drought appeared at jointing stage. Under drought conditions, increasing nitrogen fertilizer application rates promoted the grains accumulation and water use utilization efficiency of ‘Zhengdan 958’, which had the strong drought resistance. But as for ‘Denghai Super 2’, which had the weak drought resistance, the positive effects of increasing nitrogen fertilizer application rates were only appeared in drought at filling stage and full irrigation conditions. Nitrogen utilization efficiency of 2 varieties of maize decreased with increase of nitrogen fertilizer application rates. And the nitrogen fertilizer utilization efficiency of maize in drought condition at the filling stage was higher than that of other treatments (drought appeared at jointing and flowering stages, respectively). The experimental results provided a theoretical basis for water and fertilizer management of maize in the Huang-Huai-Hai region.

玉米籽粒破损是制约中国玉米籽粒直收技术推广应用的瓶颈问题,如何快速准确地获取玉米收获过程中籽粒损伤情况是玉米智能化收获的关键。为了解决这一问题,该研究提出一种基于深度学习的玉米籽粒破损检测装置及方法,该方法采用籽粒单层化装置不断获取高质量玉米籽粒集图像数据,并通过深度学习分割、分类两阶段模型实现破损玉米籽粒检测。图像分割阶段通过深度学习经典实例分割模型(Mask R-CNN)完成区域内玉米籽粒单体分割;而图像分类则由该研究基于残差模块提出的新型网络模型(BCK-CNN)实现。为了评价BCK-CNN分类模型的有效性,将其和其他典型深度学习分类模型进行对比测试,并利用可视化的技术评估了不同模型对玉米籽粒的分类性能。结果表明:BCK-CNN模型对完整、破损玉米籽粒的分类准确性分别达到96.5%、94.2%。另外,选取平均相对误差为评价指标,通过模拟试验对比验证了该检测方法对破损玉米籽粒的检测性能。结果表明:相较于人工计算籽粒破损率,该研究提出的破损玉米籽粒检测方法计算得到的平均相对误差仅4.02%;且将其部署在移动工控机上对单周期玉米籽粒集图像检测时间可以控制在1.2 s内,研究结果为玉米收获过程中破损籽粒高效精准检测提供参考。

In order to compare the effects of different concentrations（10、50、100、300 and 500 mg/L） of chitosan oligosaccharide on the germination and seedling growth of maize and rapeseed seeds, germination and seedling experiments were conducted to measure the growth indicators of maize and rapeseed. The results showed that different concentrations of chitosan had different effects on maize and rapeseed at different stages, and suitable concentrations of chitosan could promote the growth of maize and rapeseed. Maize treated with 100 mg/L chitosan seed soaking showed better growth during the germination stage, while the promotion effect of chitosan seed soaking on rapeseed germination stage was not significant. Spraying 50-100 mg/L chitosan oligosaccharide on the leaves had a better effect on promoting the growth of maize seedlings, while 500 mg/L chitosan oligosaccharide had a better effect on promoting the growth of rapeseed seedlings.

High yield has always been a research hotspot in maize breeding, and the traditional way of improving maize yield has entered the bottleneck period. The special genetic phenomenon of maize twin-embryo may provide a breakthrough direction for obtaining high yield. In order to understand the genetic mechanism of the phenomenon of twin-embryo, this paper summarized the previous studies on the phenomenon of twin-embryo and polyembryony, including maize and other crops, and integrated the related genetic expression, cytological observation, physiological and biochemical characteristics, molecular mechanism and other contents from multiple dimensions. In addition, this paper summarized some research methods of twin-embryo, to provide feasibility reference for the molecular genetic mechanism of twin-embryo traits and high-yield breeding in maize. Through previous studies, this paper found that there was no breakthrough in gene mining of twin-embryo in maize. Therefore, it is predicted that the focus of research on twin-embryo phenomenon is still the mapping of key genetic loci affecting the expression of twin-embryo traits and the mining of candidate genes, so as to further analyze the molecular network mechanism of twin-embryo phenomenon in maize and provide theoretical support for guiding maize breeding with high yield.

The Huang-Huai-Hai region is a significant production area for winter wheat and summer maize in China. Currently, the limiting factors include poor maize seeding quality due to no-tillage planting after wheat harvesting, difficulty in irrigation during the sowing to emergence period, untimely irrigation and fertilization, and poor farming techniques. Further enhancement of the use efficiency of radiation, temperature, water and fertilizer resources is the crucial way to achieve high grain yield and sustainable, green agricultural development in this region. To addresses these challenges, since 2018, we have innovated a comprehensive solution integrating several new technologies including the “four to one narrow-wide strip planting” for winter wheat, satellite-guided precision planting, annual shallow subsoil drip irrigation for synchronizing water-fertilizer-pesticide management. The corresponding modern agricultural machinery and information technology have been also matched. The integrated technique is called “Green water-fertilizer-pesticide synchronizing technology characterized of ‘four to one narrow-wide strip planting’ plus shallow subsoil drip fertigation for winter wheat-summer maize cropping system”. The field demonstration experiments conducted between 2010 and 2013 indicated that this novel comprehensive technology effectively addressed the aforementioned challenges and achieved both high yield and efficient resource utilization. Compared with traditional farmer practice, the new technology increased grain yield by 9%-17% in winter wheat and by 12%-14% in summer maize. The new technology also saved water input by 450-750 m³/hm², fertilizer input by 20%, and labor cost by 2250-3000 yuan/hm². This comprehensive technology provides a novel feasible solution for the green and high-yielding production of winter wheat and summer maize in the Huang-Huai-Hai region.

To evaluate the effect of continuous planting of transgenic maize on the community structure of soil arbuscular mycorrhizal fungi, transgenic maize DBN9936 and its non-transgenic counterpart were used as the experimental materials, the characteristics of soil arbuscular mycorrhizal (AM) fungal community structure were analyzed using PCR-DGGE and PLFA techniques. The results indicated that there was a high similarity in the soil AM fungal community structure between transgenic and non-transgenic maize in the same planting year and location. There were no significant differences in the Shannon-Wiener index, Pielou evenness index and richness. The dominant genera consistently identified were Glomus. Cluster analysis revealed that the similarity of AM fungal communities in soils from the two maize types at the same planting location was mostly above 0.60, while the similarity between communities from different locations was below 0.60. Additionally, the clustering pattern clearly separated the two maize types from different planting locations on the upper and lower sides of the cluster diagram, indicated that the community structure of soil AM fungi was greatly affected by planting sites, while the influence of the transgenic itself was weak. Phylogenetic analysis also indicated that the specific bands of the two maize species planted in different locations clustered in different groups on the phylogenetic trees. The results of soil microbial PLFA content showed that the planting of transgenic maize DBN9936 had no significant effect on the total soil microbial PLFA content, and the differences in the relative abundance of microbial groups were small. In contrast, significant differences were observed in the total PLFA content of soil microbes between the two maize types planted at different locations, with substantial variations in the relative abundance of microbial groups. In conclusion, compared to non-transgenic maize, transgenic maize DBN9936 had no significant impact on the structure of soil AM fungal communities and PLFA content. However, notable differences were observed among different planting locations.

By analyzing the response of ear traits and yield of spring sown maize to different planting densities in southern Xinjiang, this study explored the planting density suitable for southern Xinjiang, providing theoretical support for high-yield spring sown corn in southern Xinjiang. 'Tianyu 1885' was used as the test material, six planting densities were set in the plain area and the cool area of southern Xinjiang, to study the optimal density of maize cultivation in 2 different climatic regions. The density in the plain area was 90000 plants/hm², the bald tip rate and empty rod rate in the field were the lowest, at 7.5% and 1.9%, respectively. The number of panicle rows, 1000-grain weight and yield were higher than other treatments, which were 17.8 rows, 348.7 g and 15246 kg/hm², respectively. Under the densities of 75000 plants/hm² and 82500 plants/hm² treatments, spike length, number of grains in row, number of grains per spike and single rod spike weight were higher, but the effective panicle number was low, the yield was only 13232 kg/hm² and 14859 kg/hm². In the treatments with densities of 97500 plants/hm², 105000 plants/hm² and 112500 plants/hm², although the number of effective ears in the field was the highest, bald tip rate, bald tip length, empty rod rate, single rod spike weight, thousand grain weight were lower, the yields were only 14529 kg/hm², 13394 kg/hm² and 12282 kg/hm². When the density of cold area was 105000 plants/hm², spike length, grain number per spike, single rod spike weight and grain number per spike were higher than other treatments, the yield was outstanding at 17997 kg/hm². Under the treatment of 82500 plants/hm², 90000 plants/hm² and 97500 plants/hm², the bald tip length, empty stalk ratio and effective spike number were lower than other treatments, although the thousand grain weight was higher, the yields were not high at 13908 kg/hm², 14429 kg/hm² and 15825 kg/hm². Under the treatments with densities of 112500 plants/hm² and 120000 plants/hm², although the effective number of spikes was higher, the spike length, single rod spike weight and thousand kernel weight were lower, resulting in unimpressive yields of 16581 kg/hm² and 15714 kg/hm². When the density of the plain area was 90000 plants /hm² and the density of the cool area was 105000 plants/hm², corn can give full play to the developmental potential of the individual, ensure the number of ears harvested by the group, harmonize the relationship between the group and the individual, and easily obtain higher yields.

In order to select new summer maize varieties suitable for cultivation in Northwest Anhui Province, 106 maize varieties including Dongdan 6531, Fengda 611, Hua’anyu No.2, Dongdan 1971, Hua’anyu and Dongdan 905 were used as experimental materials, among which 33 varieties such as Dongdan 6531 and Hefengda 611 were planted at 60 000 plants /hm², 56 varieties such as Hua’anyu No.5 and Dongdan 1971 were planted at 75 000 plants /hm², and 17 varieties such as Hua’anyu No.5 and Dongdan 905 were planted at 90 000 plants /hm². The results showed that there were 7 excellent varieties in 60 000 plants /hm² density group (Fengda 611, Fengdecunyu 13, Quankeyu 900, Jingnongke 767, Ruihuayu 3, Ruihuayu 288 and Gushenyu 6). 15 excellent varieties (Fengda 602, Nongyu 662, Quanke 789, Fuyu 188, Yanyu 604, Shuoqiu 702, ZY806, Kangnongyu 889, Mingtian 695, Mingtian 636V2, Xianyu 1773, Denghai 1717, Hangyan 9013, K1998 and Dika 653) in the density group of 75 000 plants /hm²; There were 5 excellent varieties in 90 000 plants /hm² density group (Shuoyu 551, TH3366, Zhongkenyu 561, Jingnongyu 658 and Luyan 106). The above varieties can be further planted for demonstration in the study area.

【Objective】 Grain size and weight are the important factors affecting the yield of maize. The EIN3/EIL gene family is a sort of key transcription factors in the ethylene signaling transduction pathway, and the functions and regulatory mechanisms of the EIN3/EIL gene ZmEIL9 were analyzed in maize kernel development to elucidate its molecular mechanisms.【Method】 The expression patterns of ZmEIL9 in maize kernel at different developmental stages were analyzed by bioinformatics and RT-qPCR. The multiple sequence alignment of ZmEIL9 and its homologs from different species was performed, and the phylogenetic trees was constructed based on the neighbor-joining method. The sequence characteristics of ZmEIL9 protein were analyzed, and subcellular localization of ZmEIL9 was performed. The insertion mutants of Mu transposon and CRISPR/Cas9 knockout mutants of ZmEIL9 were screened, and the agronomic traits including grain filling rate, storage substances such as starch granule and protein content were analyzed. 【Result】 According to the members of EIN3/EIL family in maize, phylogenetic trees showed that ZmEIL9 was closely related to ZmEIL1 and SbEIL1. In the transcriptomic database of maize inbred line B73, the expression levels of ZmEIL9 were higher in the grain at early and late developmental stages. However, the expression levels were higher in inbred line N04 at the middle and late developmental stages. ZmEIL9 encoded 644 amino acids in the inbred lines Dan232 and N04, while its homolog in inbred line B73 has 642 amino acids. Subcellular localization analysis indicated that ZmEIL9 was localized in nucleus. The ZmEIL9 mutants with different Mu transposon insertion sites and CRISPR/Cas9 knockout mutants with amino acid frameshift mutations were obtained, respectively. The plant height, grain length, and 100-grain weight of Mu mutants and knockout mutants were significantly lower than those of its wild counterpart. The grain dry weights at different developmental stages were also analyzed, and the grain filling rates of Zmeil9 mutant were lower than those of the wild type. The starch granules of Zmeil9 mutant were significantly smaller and had an irregular shape based on scanning electron microscopy (SEM) observations. The contents of total starch and the concentration of zein protein in the Zmeil9 mutant were significantly lower than those in the control. 【Conclusion】ZmEIL9 plays an important regulatory role in the kernel development of maize.

【Objective】 The Huang-Huai-Hai Plain is a typical annual rotation area of winter wheat and summer maize in China, and the effect of pre-season tillage on the yield of summer maize in this area was studied, so as to provide a theoretical basis for optimizing the tillage mode under the wheat-maize double cropping system to improve the high and stable yield of summer maize. 【Method】 Based on the 6-year long-term positioning experiment, three pre-sowing tillage modes of winter wheat were set up, including Deep tillage (DT), No-tillage (NT), and Rotation tillage (RT) with deep tillage for one year and two years, to explore the tillage mode with the greatest potential for increasing summer maize yield. 【Result】 RT and DT treatments significantly increased the soil water storage of 0-40 cm soil in tillage disturbance during the tillage period of summer maize at the grain filling stage, which was 4.89% to 11.02% (2022) and 4.43% to 6.06% (2023) higher than that under DT treatment, and 8.16% to 16.69% (2022) and 6.78% to 17.23% (2023) higher than that under NT treatments, respectively. RT treatment could maintain a high leaf area index at the maize grain filling stage, and the leaf area index under RT treatment increased by 1.41% to 14.28% (2022) and 9.03% to 14.46% (2023) compared with DT treatment before and during the grain filling stage, respectively and increased by 14.80% to 27.56% (2022) and 21.25% to 29.39% (2023) compared with NT treatment, respectively. Compared with DT and NT treatments, the contribution rate of dry matter transfer after anthesis to grain under RT treatment increased by 3.77%, 40.36% (2022) and 7.26%, 19.91% (2023), respectively. The results of logistic equation simulation showed that the parameters of the 3 grain filling stages were roughly in the order of rapid growth stage>gradual growth stage>slow growth stage, and the three grain positions showed the lower grain>the middle grain>the upper grain, and the changes of the parameters in the 3 treatments showed RT>DT>NT, in which the RT treatment reached the maximum grouting rate in advance, and the average grouting rate was the highest, thereby increasing the theoretical maximum 100-grain weight. In 2022 and 2023, the yield under RT was significantly increased by 8.92%, 14.15%, 6.25% and 19.45% compared with DT and NT treatments, respectively, and in 2022 and 2023, the 100-grain weight RT and DT treatments were significantly increased by 2.71%, 6.03%, 9.02% and 12.56% compared with NT treatments, respectively. According to the structural equation model of yield formation, the direct effect and indirect effect of 0-40 cm soil water storage on yield were 0.420 and 0.551, respectively. 0-40 cm soil water storage not only directly promoted yield formation, but also affected yield through aboveground biomass and average grain filling rate. 【Conclusion】 In conclusion, soil water storage was an important driving factor for increasing yield, and RT could increase soil water storage at summer maize filling stage, thereby increasing leaf area index with higher activity, delaying leaf senescence time, increasing dry matter accumulation, optimizing grain filling characteristics, promoting the increase of dry matter to grain filling rate, and ultimately increasing summer maize yield.

This study presents an analysis of the research of purple corn anthocyanins based on 217 relevant literature from the Web of Science core collection from 1997 to 2023. The data was visualized using CiteSpace software to explore the annual publication trends, keywords, countries/regions, and institutions. The findings indicate a significant increase in the number of publications in the field of purple corn anthocyanins. The main research topics in this field include the functional activities, chemical composition, stability, and extraction methods of purple corn anthocyanins. The current research frontiers in this field encompass four aspects: the effect of purple corn on reducing or preventing diseases, the new extraction technology, the stability of anthocyanins and the application of animal husbandry. The top five research institutions in this field are from the United States, China and Thailand. The United States focuses on traditional research areas such as functional activities, stability, and extraction process, while China and Thailand concentrate on the emerging field of applied research in animal husbandry. The application of purple corn anthocyanins in livestock farming may become a future research focus.

In order to mitigate the adverse effects of drought on the development of summer maize seedlings caused by climate change, using ‘Zhengdan 958’ as experimental material, the effects of different treatment combinations on soil moisture and growth of maize seedling were studied. The results showed that the soil moisture content increased with the depth of the soil layer, and the pattern was moist soil, wheat straw returning to the field>normal moisture content, wheat straw returning to the field>moist soil, wheat straw not returning to the field>dry soil, wheat straw returning to the field>normal moisture content, wheat straw not returning to the field>dry soil, wheat straw not returning to the field. SPAD value, photosynthetic rate and yield showed the same trend, normal moisture content, wheat straw returning to the field>moist soil, wheat straw returning to the field>moist soil, wheat straw not returning to the field>normal moisture content, wheat straw not returning to the field>dry soil, wheat straw returning to the field>dry soil, wheat straw not returning to the field. Therefore, compared with the removal of stubble, plain stubble can better improve the soil water environment, increase the emergence rate and photosynthetic rate of maize, and increase the yield, which can be widely applied in production.

To screen the best cultivation measures for soybean-maize intercropping, the effects of sowing date, density and fertilizer application rate on main traits and yield of soybean were studied by three-factor and three-level orthogonal test. The results showed that choosing fresh corn and soybean compound planting enabled soybeans to have a long photoperiod after corn harvest; increasing plant height, number of nodes in the main stem, number of effective pods per plant, number of grains per plant, 100-grain weight, and grain weight per plant had a facilitating effect on soybean yield, while the number of grains per plant, grain weight per plant, and hundred-grain weight had a decisive effect on the yield. Condensation analysis showed that cultivation with sowing period from April 30 to May 10, density of 210000-240000 plants/hm², and fertilizer application rate of 300-375 kg/hm² could obtain higher yield.

To investigate the effects of nitrogen and phosphorus double removal and reduction on yield, dry matter accumulation and translocation of spring maize under shallow buried drip irrigation, the four treatments of N₂P₂ nitrogen and phosphorus constant, N₂P₂ nitrogen fertilizer 30% reduction, N₂P₂ phosphorus fertilizer 30% reduction and N₂P₂ nitrogen and phosphorus both 30% reduction were set up to determine the SPAD value, leaf area index, dry matter accumulation and yield of spring maize using conventional fertilization as the control. The results showed that compared with CK, yield of N₂P₂ increased by 4.71% and 3.84% in 2019 and 2020, and the leaf SPAD value, leaf area index increased, dry matter accumulation and translocation contribution to kernel and yield all increased significantly. Under the nitrogen and phosphorus double removal, constant fertilizer application increased the dry matter accumulation and improved the dry matter transport to grain; the dry matter accumulation, translocation contribution to seed grain and yield all decreased under 30% reduction of phosphorus and nitrogen fertilizer; the yields of 2019 and 2020 respectively decreased by 3.22% and 3.84% under 30% reduction of phosphorus fertilizer at the N₁ level, and the yields of 2019 and 2020 respectively decreased by 8.23% and 16.35% under 30% reduction of nitrogen fertilizer at the P₁ level.

To study the effect of banded composite planting pattern on maize material production and distribution in Ningxia irrigation area. This study explored the impact of the soybean-corn strip compound planting model located in the Ningxia irrigated area on the production and distribution of corn matter. Four kinds of strip composite planting patterns demonstrated and planted in Ningxia were selected for the experiment, soybean-corn S3:M2, S4:M2, S3:M4, S4:M4, with the control being monoculture corn (M). The maize test varieties was ‘Xianyu 1225’, the soybean varieties for test was ‘Zhonghuang 30’, the maize planting density was 82500 plants/hm2, and the soybean planting density was 150000 plants/hm2. The test results showed that compared with monoculture corn, the dry matter of corn planted in strip composite planting at maturity was reduced by 7.9%-30.4% per plant, with the smallest effect of S3:M4 and the largest effect of S4:M2; the total dry matter at maturity was reduced by 4.3%-42.7%. The dry matter allocation of female ears at maturity was reduced by 0.5% to 40.5%, with S3:M4 having the smallest effect and S4:M2 having the largest effect. Corn yield was reduced by 25.1% to 41.4%, the number of ears harvested decreased by 4.2% to 14.9%, thousand kernel weights decreased by 0.5% to 3.6%, and the number of grains per ear decreased by 5.2% to 10.8%. Soybean-corn strip composite planting pattern had less dry matter in the female ears than corn alone, and the accumulation of dry matter in the female ears at the spatula stage began to decrease, and the yield was reduced.

In order to comprehensively grasp the research trends of waxy corn in China, the journal papers from 2002 to 2022 included in the CNKI journal database were taken as the research object, and the analysis was carried out from the aspects of the number of papers, institutions, authors, journals, highly cited papers, and keyword co-occurrence by Excel, SATI, and VOSviewer. The results showed that the average annual number of papers published in all Chinese waxy corn research journals was 229, with 343 core authors. The core journal had an average annual of 59 articles and 146 core authors. Shanxi Academy of Agricultural Sciences had the largest number of papers and Yangzhou University had the largest number of core journals papers. The largest number of articles published in Agricultural Science and Technology Newsletter was 254, accounting for 5.27% of the total number of documents. The core journal Maize Science had a maximum of 157 papers, accounting for 12.66% of the total number of papers. The highly cited papers were published in the journal with high academic level, such as Chinese Agricultural Science, Journal of Crops, and Maize Science with high citation of more than 50%, highlighting their core position and academic level. The keyword co-occurrence figures revealed that the waxy corn researches mainly involved the following aspects: (1) the cultivation of waxy corn, including the influence of cultivation modes and factors on the growth and yield of waxy corn; (2) the quality of waxy corn, including its starch characteristics and nutritional value; (3) germplasm resources and breeding techniques of new waxy corn varieties; (4) research on biological stress of waxy corn; (5) the impact of abiotic stress on the growth of waxy corn; (6) the problems and development strategies in the development of waxy corn industry; (7) the processing and preservation technology of waxy corn. In future waxy corn research, we can focus on creating high-quality waxy corn germplasm, quality research of waxy corn, research of efficient breeding technology systems and breeding high-quality new varieties, and standardized and efficient planting techniques.

为探究2-(3,4-二氯苯氧基)乙基二乙胺(2-(3,4-dichlorophenoxy) ethyl triethylamine,DCPTA)在干旱胁迫下对玉米种子萌发的影响,使用聚乙二醇(polyethylene glycol-6 000,PEG-6 000)和浓度为0.5、1.0、1.5 mg/L的DCPTA混合溶液对玉米种子进行浸泡处理,采用种子标准发芽试验总结得出不同浓度的DCPTA对玉米种子发芽情况影响的规律,再结合低场核磁共振(low field nuclear magnetic resonance,LF-NMR)及核磁共振成像(magnetic resonance imaging,MRI)技术,通过研究其内部水分变化情况、水分迁移规律及水分分布特征解释造成该结果的原因。试验结果表明:一定浓度的DCPTA可以提高玉米种子萌发过程中的耐旱性能,加快种子内部水分的存储速率,提供种子萌发所需的水分条件,减轻干旱胁迫对玉米种子造成的损害。DCPTA对玉米种子干旱胁迫的缓解效果随着其浓度的升高呈现先上升后下降的趋势,以1.0 mg/L的DCPTA处理效果最显著(P<0.05)。该研究有助于揭示DCPTA缓解干旱胁迫下玉米种子萌发的内部变化规律,可为提高玉米种子抗旱性的相关研究提供重要手段。

Maize varieties Zhengdan 958, Anke 985, and Huangjinliang MY73 were used as materials, the effects of different planting density (67 500, 82 500, 90 000, 97 500, and 105 000 plants/hm²) on maize root growth under drip irrigation and conventional fertilization conditions were studied. The results showed that with the increase of corn planting density, the dry weight of corn roots, aerial roots, and subterranean roots all showed a decreasing trend. The effects of different fertilization methods on the growth of maize underground roots vary, and drip irrigation fertilization technology could promote maize root growth. The root system characteristics of variety Huangjinliang MY73 were relatively good. Planting density of 67 500 plants/hm² under drip irrigation and fertilization conditions could help promote the growth and development of maize roots.

The production practice of summer corn was combined in Taihe County, Fuyang City, Anhui Province, and its high-yield cultivation techniques were summarized and analyzed. Fine soil preparation before planting, using precision farming methods to improve soil structure. Select high-yield, high-quality, and highly resistant varieties, and conduct sorting and chemical seed mixing treatment. Sow at the appropriate time and plant closely to maximize its yield potential. During the planting process, ensure an appropriate supply of water, timely weed control, and balanced fertilization to meet the fertilizer and water needs of crops at different growth stages. Simultaneously adopting multiple methods to comprehensively prevent and control diseases and pests such as ear rot, rust, and corn borer. After maturity, harvest should be postponed appropriately to achieve the goal of increasing yield. Through scientific and rational planting techniques, soil nutrient content can be effectively increased, summer corn growth can be promoted, and its yield and quality can be improved.

To study the effect of planting density on yield and its components, 4 main cultivated cultivars in east Henan Province were investigated respectively under 4 different production environments, adopting the method of randomized block test design. The results showed that the rate of empty stalk increased along with the increase of planting density, grain number per spike declined with the increase of density with a negative linear correlation, the effect of planting density on number of grains per ear was not significant and the results varied with different cultivars; the declining trend of 1000- grain weight was obvious along with the increase of density and a negative linear correlation existed; the grain yield increased first and then decreased with the density increasing; suitable planting densities were listed. ‘Denghai 605’ was 60000-82500 plants/hm², and the optimum density was 69102 plants/hm²; ‘Meijia 605’ was 60000-75000 plants/hm², and the optimum density was 72277 plants/hm²; ‘Zhongke 505’ was 52500-67500 plants/hm², and the optimum density was 60727 plants/hm²; ‘MY73’ was 60000-82500 plants/hm², and the optimum density was 72141 plants/hm².

The footprints of water and nitrogen (WF and NF) provide a comprehensive overview of the type and quantity of water consumption and reactive nitrogen (Nr) loss in crop production. In this study, a field experiment over two years (2019 and 2020) compared three integrated agronomic practice management (IAPM) systems: An improved management system (T2), a high-yield production system (T3), and an integrated soil-crop management system (ISCM) using a local smallholder farmer's practice system (T1) as control, to investigate the responses of WF, Nr losses, water use efficiency (WUE), and nitrogen use efficiency (NUE) to IAPM. The results showed that IAPM optimized water distribution and promoted water use by summer maize. The evapotranspiration over the whole maize growth period of IAPM increased, but yield increased more, leading to a significant increase in WUE. The WUE of the T2, T3, and ISCM treatments was significantly greater than in the T1 treatment, in 2019 and 2020 respectively, by 19.8-21.5, 31.8-40.6, and 34.4-44.6%. The lowest WF was found in the ISCM treatment, which was 31.0% lower than that of the T1 treatment. In addition, the ISCM treatment optimized soil total nitrogen (TN) distribution and significantly increased TN in the cultivated layer. Excessive nitrogen fertilizer was applied in treatment T3, producing the highest maize yield, and resulting in the highest Nr losses. In contrast, the ISCM treatment used a reduced nitrogen fertilizer rate, sacrificing grain yield partly, which reduced Nr losses and eventually led to a significant increase in nitrogen use efficiency and nitrogen recovery. The Nr level in the ISCM treatment was 34.8% lower than in the T1 treatment while NUE was significantly higher than in the T1 treatment by 56.8-63.1% in 2019 and 2020, respectively. Considering yield, WUE, NUE, WF, and NF together, ISCM should be used as a more sustainable and clean system for sustainable production of summer maize.

Soil microorganisms play critical roles in ecosystem function. However, the relative impact of the potassium (K) fertilizer gradient on the microbial community in wheat‒maize double-cropping systems remains unclear. In this long-term field experiment (2008-2019), we researched bacterial and fungal diversity, composition, and community assemblage in the soil along a K fertilizer gradient (in the wheat season: K0, no K fertilizer; K1, 45 kg ha⁻¹ K₂O; K2, 90 kg ha⁻¹ K₂O; K3, 135 kg ha⁻¹ K₂O; and in the maize season: K0, no K fertilizer; K1, 150 kg ha⁻¹ K₂O; K2, 300 kg ha⁻¹ K₂O; K3, 450 kg ha⁻¹ K₂O) using bacterial 16S rRNA and fungal ITS data. We observed that environmental variables (such as mean annual soil temperature (MAT) and precipitation, available K, ammonium, nitrate, and organic matter) impacted the soil bacterial and fungal communities, and their impacts varied with fertilizer treatments and crop species. Furthermore, the relative abundance of bacteria involved in soil nutrient transformation (phylum Actinobacteria and class Alphaproteobacteria) in the wheat season was significantly increased compared to the maize season, and the optimal K fertilizer dosage (K2 treatment) boosted the relative bacterial abundance of soil nutrient transformation (genus Lactobacillus) and soil denitrification (phylum Proteobacteria) bacteria in the wheat season. The abundance of the soil bacterial community promoting root growth and nutrient absorption (genus Herbaspirillum) in the maize season was improved compared to the wheat season, and the K2 treatment enhanced the bacterial abundance of soil nutrient transformation (genus MND1) and soil nitrogen cycling (genus Nitrospira) genera in the maize season. The results indicated that the bacterial and fungal communities in the double-cropping system exhibited variable sensitivities and assembly mechanisms along a K fertilizer gradient, and microhabitats explained the largest amount of the variation in crop yields, and improved wheat‒maize yields by 11.2-22.6 and 9.2-23.8% with K addition, respectively. These modes are shaped contemporaneously by the different meteorological factors and soil nutrient changes in the K fertilizer gradients.

【Objective】Soybean and maize strip intercropping is an important cultivation pattern for soybean productivity improvement project in China. In this experiment, the effects of straw returning and irrigation methods on the emergence and seedling growth quality in soybean and maize strip intercropping were investigated, in order to provide the theoretical support for the strip intercropping to solve the problem of seedling emergence.【Method】Two-factor split plot zone design was adopted, three straw returning methods (non-returning straw (S1), returning straw with no stubble (S2), and returning straw with stubble (S3)) and three irrigation methods (non-irrigation (W1), check irrigation before sowing (W2), and spray irrigation after sowing (W3)) were set up, and their effects on seedling emergence and growth of strip intercropping crops were researched.【Result】Irrigation could significantly increase soil water content and alleviate soil compactness, thus effectively improving the emergence rate of soybean and maize, and shortening the emergence time. The seedling emergence rates under W3, W2 and W1 with S2 were 71.00%, 45.70% and 38.50% in Yucheng, respectively. The seedling emergence rates under W3, W2 and W1 with S2 were 90.17%, 88.50% and 61.67% in Anju, respectively. The emergence time under W2 and W3 was 3.29 d and 2.92 d shorter than that under W1, respectively. Under different irrigation methods, there was no significant difference in the seedling emergence rate of maize, which could reach more than 90%, but the seedling emergence time was significantly different. The emergence time of maize under W2 and W3 was 1.9 d and 3.1 d shorter than that under W1 in Yucheng, respectively. The emergence time of maize under W2 and W3 was 0.96 d and 0.6 d shorter than that under W1 in Anju, respectively. Straw returning significantly increased soil water content and decreased soil compactness, and the effects in both places were S2>S3>S1. Straw returning to the field under W1 could significantly improve the soybean seedling emergence rate in Yucheng, in which S2 was 45.08% higher than S1. Straw returning had no significant effect on the emergence rate of maize in the two places. Straw returning and irrigation significantly increased the activity of soybean lipase (LPS) and maize α-amylase (α-AL). The LPS of W2 and W3 were 26.86% and 37.77% higher than that of W1, respectively. The LPS under S2 was 14.14% and 18.05% higher than that under S3 and S1, respectively. The α-AL under W2 was 189.47% higher than that under W1, and the α-AL under S2 was 61.52% and 127.33% higher than that under S3 and S1, respectively. The two irrigation treatments could promote the growth and development of soybean and maize, and improve the seedling growth rate and uniformity. The soybean plant height under W3 and W2 was 21.74% and 15.70% higher than that under W1, respectively, wihle the stem diameter was 12.52% and 28.15% higher, respectively, and the leaf area was 11.84% and 38.78% higher, respectively. The maize plant height under W3 and W2 was 21.80% and 20.62% higher than that under W1, respectively, while the stem diameter was 37.69% and 26.39% higher than that under W1, respectively, and the leaf area under W3 was 36.56% and 73.33% higher than that under W2 and W1, respectively. Straw returning significantly affected the growth of maize seedlings in Yucheng, showing S3>S1>S2. The plant height under S3 was 19.92% and 27.31% higher than that under S1 and S2, respectively, while the stem diameter was 27.59% and 59.80% higher, respectively, and the leaf area was 42.76% and 68.54% higher, respectively.【Conclusion】Successful emergence and construction of a good seedling population were the basis for achieving high yield. Spray irrigation after sowing improved the physical structure of the plough layer, thus promoted the emergence of seedlings and shortened the emergence time in strip intercropping, and provided favorable conditions for subsequent crop growth. Returning straw with stubble could improve the growth quality of strip intercropping seedlings in Yucheng. Returning straw with no stubble had the characteristics of water storage and alleviating soil compaction, it is beneficial to soybean emergence without irrigation, and has a promoting effect on the formation of strong seedlings of strip intercropping crops in Anju.

【Objective】The objective of this study is to clone the small heat shock protein (sHSP) genes in Setosphaeria turcica, elucidate their structural characteristics, and explore their expression profiles during pathogen development and in response to HT-toxin induction.【Method】The hidden Markov model (HMM) was used to identify sHSP family members across the entire S. turcica genome. PCR technology was used to clone sHSP genes from S. turcica strain 01-23. Bioinformatics methods were then applied for the analysis of physicochemical properties, subcellular localization, structural prediction, and phylogenetic analysis of the sHSP genes obtained. Additionally, RNA-Seq and RT-qPCR were performed to determine the expression of sHSP genes across different developmental stages and during HT-toxin induction in S. turcica.【Result】Three sHSP family members (StHSP37.2, StHSP37.0 and StHSP22.6) were identified from the genome of S. turcica. The corresponding DNA sequences were successfully cloned from strain 01-23. The encoded sHSP proteins were weakly acidic and hydrophilic proteins, without transmembrane domain or signal peptide. Random coil in the secondary structure accounted for 58.97% to 60.35%, and β-turn ranged from 2.69% to 7.83% only. Subcellular localization prediction indicated that StHSP37.2 and StHSP37.0 were located in the nucleus, while StHSP22.6 was located in both nucleus and cytoplasm. Conserved ACD_sHSP-like domains were identified near C-terminus, with 2, 3, and 5 conserved motifs in StHSP37.2, StHSP37.0, and StHSP22.6, respectively. The monomer tertiary structure models of sHSP were constructed using SWISS-Model and AlphaFill. Phylogenetic analysis indicated close relationships between StHSP22.6 and sHSP in Alternaria alternata, and between StHSP37.2/StHSP37.0 and sHSP in Bipolaris maydis. The sHSP genes of S. turcica had the highest expression levels in hyphae, followed by germ tubes, appressoria, and penetration pegs, with the lowest expression levels in conidia. StHSP22.6 and StHSP37.2 showed significant negative correlations with HT-toxin induction, and the relative gene expression was upregulated by 6.45 and 18.12 folds on day 14, respectively. On day 21 and 28, StHSP37.2 showed modest upregulations of 2.56 and 1.78 folds, respectively, while StHSP22.6 did not differ from the wild-type (WT). StHSP37.0 exhibited significant positive correlations with HT-toxin induction, with a significant downregulation by 59.23%, 86.30%, and 88.11% on day 14, 21, and 28, respectively. Exploration of expressed genes significantly associated with sHSP of S. turcica suggested that StHSP37.2 and StHSP22.6 were mainly related to HSP90, HSP104, catabolism, and mitochondrial Mg²⁺ transport, while StHSP37.0 appeared to be associated with vacuolar alkaline amino acid transport, organic synthesis, and substance secretion.【Conclusion】The sHSP family members in S. turcica demonstrate a high degree of conservation yet exhibit structural and phylogenetic differences from other sHSPs. They are integral to the development of hyphae, germ tubes, appressoria, and penetration pegs, and also exert significant regulatory functions during HT-toxin induction.

【Objective】Crop nitrogen nutrition status is a key indicator to characterize the green degree and health status of maize canopy. In order to compare the accuracy of single spectral index model and texture information fusion model in maize nitrogen nutrition estimation model, this investigated the accuracy and reliability of maize nitrogen nutrition estimation model based on UAV multispectral information and texture information fusion. 【Method】 Matrice-300 RTK multi-rotor aircraft equipped with MS600 Pro multi-spectral sensor was used to obtain multi-spectral images of maize tasseling-silking stages under six nitrogen levels in two years. By extracting vegetation index and texture features, the correlation between vegetation index, single texture feature, combined texture index and fusion information of vegetation index and texture index, was comprehensively analyzed. The vegetation index, normalized difference texture index (NDTI) and their combined parameters with the largest amount of information were selected. Four nitrogen nutrition parameters of maize leaf nitrogen content (LNC), plant nitrogen content (PNC), leaf nitrogen accumulation (LNA), and plant nitrogen accumulation (PNA) were compared and estimated by multiple stepwise regression (MSR), random forest (RF), support vector machine (SVM), and grey wolf optimized convolutional neural network ( GWO-CNN ). 【Result】 (1) There were differences in the original spectral reflectance of maize under different nitrogen treatments, and the differences in the red band R (660 nm), blue band B (450 nm) and near-infrared band NIR (840 nm) were significant. (2) The vegetation indices (EVI, GARI, REOSAVI, SIPI, and MCARI), single texture features (var₄₅₀, var₆₆₀, mean₈₄₀, dis₇₂₀, and hom₈₄₀) and combined texture index NDTI extracted from UAV multispectral images could be used for LNC, PNC, LNA and PNA estimation of maize in VT-R1 stage. The GWO-CNN model based on vegetation index had better estimation effect on LNC, PNC, LNA and PNA than single texture feature and texture index model, and its R² were 0.831, 0.761, 0.826 and 0.770, respectively. (3) The accuracy of GWO-CNN model with vegetation index and texture index for LNC, PNC, LNA and PNA estimation was significantly higher than that of vegetation index and texture index, and its R² was 0.921, 0.901, 0.917 and 0.892, respectively, which was 9.77%, 15.54%, 9.92% and 13.68% higher than that of single spectral information optimal estimation model. 【Conclusion】 Fusion of multi-spectral vegetation index and texture index could effectively improve the estimation accuracy of maize nitrogen nutrition, and better evaluate the distribution of maize nitrogen distribution, which provided new ideas for precise maize nitrogen fertilizer management based on UAV platform at field scale.

The common types of pests and diseases in corn production and their harmful symptom were reviewed, and strategies for the control of corn pests and diseases were explained from the aspects of agricultural control, biological control, physical control, and chemical control. Diseases such as top rot, bacterial stalk rot, leaf spot, sheath blight, and rust were commonly found in corn, while common insect pests include armyworms, corn aphids, corn borers, and thrips. The effective control of pests and diseases issues in the corn planting process was achieved through the comprehensive use of various means such as biological control, chemical control, and precision agriculture techniques, thereby ensuring the yield and quality of corn. A reference for the scientific and efficient control of pests and diseases in corn production was provided.