Long-term straw return is a key measure for enhancing soil organic carbon (SOC). However, the mechanisms by which prolonged straw return influences SOC accumulation through soil microbial community regulation according to maize growth stage remain unclear. This study was based on a long-term field plot experiment in which soil biochemical properties were measured at three critical maize growth stages—jointing (V12), tasseling and silking (R1), and milk (R3)—under straw return practices of 5, 7, and 9 years, as well as under a no-straw-return control. Effects on SOC content, microbial communities, and their functional attributes were investigated. Long-term straw return generally increased the contents of SOC, microbial biomass carbon (MBC), total nitrogen (TN), available phosphorus, and total phosphorus; however, the response varied according to duration of straw return. Straw return duration and maize growth stage jointly shaped microbial community structure; fungal diversity showed greater sensitivity to growth stage variation. During growth progression, the relative abundance of Actinobacteria increased, enhancing soil capacity for straw decomposition. Predictive functional profiling suggested that long-term straw return can enhance bacterial chemoautotrophic pathway activity and aerobic nutrient-related processes, while promoting straw assimilation and utilization. Fungal communities, primarily characterized by saprotrophic nutrition, were predicted to play major roles in the potential decomposition of cellulose, hemicellulose, and lignin, thus regulating soil carbon cycling. Structural equation modeling revealed that a 7-year straw return strategy achieves optimal SOC sequestration by positively regulating fungal communities; MBC and TN served as key mediating factors in SOC enhancement. This study establishes an optimized field management strategy for straw return in black soil regions and provides theoretical support for advancing sustainable agriculture through coordination of the straw–microorganism–SOC interaction. However, considering soil type specificity and environmental variability, further research across diverse agroecosystems is required to verify the broader applicability of these mechanisms.

Soil salinization in farmland is a critical factor limiting global soil health, food security, and ecosystem productivity. Biochar has recently shown great application potential in agricultural fields in many domains, such as soil structure improvement, carbon sequestration, and reductions in greenhouse gas emissions. Here, a meta-analysis of 113 published papers was carried out to quantify the effects of biochar on the remediation of saline-alkali soil and crop yield in terms of climatic conditions and agricultural management, with the aim of determining the optimal agricultural management strategy for biochar application to saline-alkali soils. The results show that adding biochar to saline-alkali farmland increases the TOC in soil (44.0%) and water utilization efficiency (8.7%), and decreases soil salinity (−9.6%), certain salt ion contents in particular (Na+, 12.5%; Cl−, 23.4%; HCO3−, −17.7%), along with soil pH (−2.2%), resulting in a 20.8% higher crop yield. Applying shell biochar at a rate of 10–20 t·ha−1 for monoculture is the most promising way to bolster the yield in severely saline-alkali irrigated farmland. However, adding biochar raises CO2 and CH4 emissions by 9.8% and 31.6%, respectively, but lowers the emission of N2O by 29.4%. These findings provide scientific recommendations for the sustainable application of biochar in saline-alkali farmland areas worldwide.

Drip irrigation (DI) could effectively reduce greenhouse gas (GHG) emissions from dryland agriculture, helping mitigate global warming. Here, we performed a meta-analysis to quantify the effects of dryland DI on GHG emissions under different climatic conditions, soil conditions, and agricultural management practices. The results showed that DI can reduce GHG emissions by decreasing the soil moisture content (i.e., water-filled pore space). The N2O and CO2 emissions decreased by 29.2% and 6.1%, respectively, and global warming potential decreased by 18.7%, but CH4 emissions increased by 9.7%-14.0%. When the irrigation scheduling was higher than 70% and the nitrogen application was 180-300 kg ha-1, shallow buried DI with water flow controlled below 2 L hr-1 was the best strategy for emission reduction. In addition, compared with traditional irrigation methods, DI demonstrates greater long-term effectiveness in reducing N2O and CO2 emissions. We also found that greenhouse vegetable production combined with DI has great potential for reducing GHG emissions. This study provides evidence for the application of DI technology to reduce global dryland GHG emissions.

Continuous monocropping, intercropping, and crop rotation are common planting patterns in the black soil region of Northeast China, but it remains unclear which pattern is more advantageous for simultaneously improving rhizosphere soil biological properties and enhancing crop yield. Therefore, we established a field experiment with three maize cropping systems (continuous maize cropping, maize-soybean rotation, and continuous maize-soybean intercropping) and investigated soil biological properties and yields over five consecutive years. The maize yield (per planted hectare) under the rotation treatment was 12.37 % and 8.38 % higher than that under intercropping and continuous cropping, respectively. The rotation treatment also effectively stabilized the soil pH and enhanced soil nutrient contents, particularly the total nitrogen (TN) content, which accumulated by 39.88 % over five years under the rotation treatment. Additionally, crop rotation improved rhizosphere soil catalase, urease, and acid phosphatase activities by 2.83 %-12.88 %, and boosted rhizosphere soil bacterial community richness and diversity by 12.79 %-16.93 %. Bradyrhizobium exhibited the highest relative abundance under crop rotation, and the enrichment of this genus significantly elevated bulk soil nitrogen content and maize yield. In contrast, the enrichment of Nocardioides and Pseudarthrobacter reduced maize yield. Our findings offer a theoretical basis for the optimal management and sustainable development of intensive crop cultivation in the black soil region of Northeast China.

Chemical products, such as seed dressings, are often used to regulate crop growth and development and improve yields. In this study, we investigated a seed dressing containing 0.136% gibberellic acid (GA), indole-3-acetic acid (IAA)-, and brassinolide (BL) as a wettable powder (WP), hereafter referred to as GA-IAA-BL WP. This product is a new plant growth regulator of plant origin that can improve crop stress resistance and yield. However, its effect on maize seed germination and seedling growth under low-temperature stress is unclear. In this study, GA-IAA-BL WP was applied to maize ‘Liukexing 99’ seeds at 50, 100, 150, or 200 mg mL−1, and seeds were germinated in an artificial climatic chamber at 10, 15, or 25 °C for 14 d. Application at 100 mg mL−1 significantly increased the germination rate as well as seedling shoot and root length and dry and fresh weight at all three temperatures. This application rate also increased the contents of proline, malondialdehyde, soluble sugars, and soluble proteins; the activities of catalase, superoxide dismutase, and peroxidase; and root vigor. Our results demonstrate that GA-IAA-BL WP can reduce the negative impacts of low-temperature stress on seed germination and seedling growth.

Crop rotation increases crop yield, improves soil health, and reduces plant disease. However, few studies were conducted on the use of intensive cropping patterns to improve the microenvironment of saline soils. The present study thoroughly evaluated the impact of a three-year maize-peanut-millet crop rotation pattern on the crop yield. The rhizosphere soil of the crop was collected at maturity to assess the effects of crop rotation on the composition and function of microbial communities in different tillage layers (0-20 cm and 20-40 cm) of sandy saline-alkaline soils. After three years of crop rotation, the maize yield and economic benefits rose by an average of 32.07% and 22.25%, respectively, while output/input grew by 10.26%. The pH of the 0-40 cm tillage layer of saline-alkaline soils decreased by 2.36%, organic matter rose by 13.44%-15.84%, and soil-available nutrients of the 0-20 cm tillage layer increased by 11.94%-69.14%. As compared to continuous cropping, crop rotation boosted soil nitrogen and phosphorus metabolism capacity by 8.61%-88.65%. Enrichment of Actinobacteria and Basidiomycota increased crop yield. Crop rotation increases microbial community richness while decreasing diversity. The increase in abundance can diminish competitive relationships between species, boost synergistic capabilities, alter bacterial and fungal community structure, and enhance microbial community function, all of which elevate crop yields. The obtained insights can contribute to achieving optimal management of intensive cultivation patterns and green sustainable development.

Currently, China’s soybean self-sufficiency rate is only 15%, highlighting the soybean crisis and the supply chain risks that pose a major threat to China’s food security. Thus, it has become imperative to step up efforts to boost soybean production capacity while promoting the green and sustainable development of regional farmland ecosystems. In this context, the present study comprehensively investigated the effects of intercropping and nitrogen application rate on soybean yield, as well as the changes in gradients generated by different levels of nitrogen application. Based on six consecutive years of maize–soybean intercropping planting patterns, the inter-root soils of soybeans were collected at the flowering stage and evaluated for soil nitrogen content, nitrogen-assimilating enzyme activities, and microbial community composition of soybean, which were correlated with yield, to clarify the main pathways and modes of intercropping effects. The N2 level (80 kg·ha−1) was favourable for higher yield. In comparison to monocropping, the intercropping reduced yield by 9.65–13.01%, photosynthetic characteristics by 1.33–7.31%, and plant nitrogen-assimilating enzyme activities by 8.08–32.01% at the same level of N application. Likewise, soil urease and catalase activities were reduced by 9.22 and 1.80%, while soil nitrogen content declined by an average of 6.38%. Gemmatimonas and Bradyrhizobium enrichment significantly increased soil nitrogen content, photosynthetic characteristics, and soybean yield, while it was reduced by Candidatus_Udaeobacter and Candidatus_Solibacte enrichment. The results of this study provide a theoretical basis for further optimising maize–soybean intercropping, which is crucial for enhancing the agricultural production structure and improving the overall soybean production capacity.

Background and aims The practice of returning corn stalks back to fields is widely implemented in maize cropping systems, but its impacts on maize yield is inconsistent due to different methods employed. We hypothesized soybean-maize rotation system with returning crop stalks to enhance soil health and maize yield. Methods A field trial was carried out from 2013 to 2018, comparing a soybean-maize rotation system with sole maize cultivation. Soil physicochemical properties, agronomic traits of maize and soil microbial community were determined. Results Maize yield and ear diameter were significantly higher in the rotational cropping system in 2018, compared to monocropping. Over the years, organic matter contents remained stable in the soil under rotational cropping but decreased in the monocropping soil. Different cropping systems also led to shifts in soil microbial communities: rotational cropping augmented fungal diversity, though the overall compositions of bacterial and fungal communities did not significantly differ between the two cropping systems. The proliferation and beneficial impact of functional microorganisms involved in crop residue decomposition, biological control of soil-borne disease, nutrient metabolism, and nutrient uptake were closely related to the improvement of maize yield and soil nutrition within the rotational cropping system. Conclusions Maize-soybean rotation and plant residue return sustained increased maize yield and organic matter contents of soil. The overall effect of the soil microbiome exhibited a positive association with both soil health and maize yield. This study highlights the potential of combining crop residue returns with crop rotation in bolstering soil health and fostering increased maize yield.

IntroductionIntercropping practices play a crucial role in enhancing and maintaining the biodiversity and resiliency of agroecosystems, as well as promoting stable and high crop yields. Yet the relationships between soil nitrogen, microbes, and yield in maize cultivated under maize/soybean intercropping systems remain unclear.MethodsTo fill that knowledge gap, here we collected maize rhizosphere soil at the staminate stage after 6 consecutive years of maize/soybean intercropping, to investigate how intercropping and nitrogen application rates affected nitrogen utilization by crops and soil microbial community composition and function. We also examined correlations of those responses with yields, to clarify the main ways that yield is enhanced via intercropping and by nitrogenous fertilizer gradient changes generated by different nitrogen application rates.ResultsThe amount of applied fertilizer was 240 kg N ha-1 was best for obtaining a high maize yield and also led to the greatest nitrogen-use efficiency and bacterial diversity. Under the same N application rate, intercropping increased the maize yield by 31.17% and soil nitrogen (total, ammonium and nitrate nitrogen) by 14.53%, on average, in comparison to monocropping. The enrichment of Gemmatimonas and Bradyrhizobium significantly increased the soil nitrogen content, and a greater relative abundance of Sphingomonas and Gemmatimonas increased the maize yield, whereas enrichment of Candidatus_Udaeobacter and Bradyrhizobium decreased it. The benefits of intercropping mainly arise from augmenting the abundance of beneficial microorganisms and enhancing the efficiency of N use by crop plants.DiscussionThis study’s findings are of key importance to bolster the stability of agro-ecosystems, to guide the scientific rational use of nitrogen fertilizers, and to provide a sound theoretical basis for achieving the optimal management of intensive crop-planting patterns and green sustainable development.

Soil-borne diseases are exacerbated by continuous cropping and negatively impact maize health and yields. We conducted a long-term (11-year) field experiment in the black soil region of Northeast China to analyze the effects of different cropping systems on maize yield and rhizosphere soil fungal community structure and function. The experiment included three cropping systems: continuous maize cropping (CMC), maize–soybean rotation (MSR), and maize–soybean intercropping (MSI). MSI and MSR resulted in a 3.30–16.26% lower ear height coefficient and a 7.43–12.37% higher maize yield compared to CMC. The richness and diversity of rhizosphere soil fungi were 7.75–20.26% lower in MSI and MSR than in CMC. The relative abundances of Tausonia and Mortierella were associated with increased maize yield, whereas the relative abundance of Solicoccozyma was associated with decreased maize yield. MSI and MSR had higher proportions of wood saprotrophs and lower proportions of plant pathogens than CMC. Furthermore, our findings indicate that crop rotation is more effective than intercropping for enhancing maize yield and mitigating soil-borne diseases in the black soil zone of Northeast China. This study offers valuable insights for the development of sustainable agroecosystems.

Soil acidification is a global environmental problem with significant impacts on agricultural production, environmental protection, and ecosystem health. Soil acidification is widespread in China, affecting crop yields, agricultural product quality, and biodiversity. Since the 1980s, much work has been done on acidic soils in China, but it is controversial whether excessive nitrogen fertilizer application can lead to soil acidification mechanisms. To address the above issues, we conducted a meta-analysis of 115 published papers to integrate and analyze the effects of N fertilizer application on soil acidification and biological properties from 1980 to 2024. We also quantified the effect of nitrogen fertilization on soil acidification and biological changes under different climatic conditions. The results showed that under long-term application of nitrogen fertilizers in China from 1980 to 2024, soil pH decreased by an average of 15.27%, and the activities of soil urease, nitrate reductase, nitrite reductase, catalase, glutamate dehydrogenase, and glutamate synthetase decreased by an average of 9.82–22.37%. The soil microbial community richness (Chao1 index) increased by 6.53%, but the community diversity (Shannon index) decreased by 15.42%. Among the dominant soil microorganisms, the relative abundance of bacteria decreased by an average of 9.67–29.38% and the abundance of gene expression of nifH, amoA-AOA, amoA-AOB, and qnorB decreased by 9.92–19.83%. In addition, we found that the mean annual temperature and rainfall impacted soil acidification via their effect on soil microbial diversity and community composition. This study provides a scientific basis for an in-depth understanding of the spatial and temporal variation of soil acidification and biological properties in China.

基于对吉林省长春市大田土壤温度和水分变化分析,研究不同播种日期对春玉米出苗率及产量的影响,确定最佳播种日期,为提高吉林省春玉米产量提供理论依据.以春玉米品种松玉419为试验材料,田间设置9个不同播种日期,播期间隔5～6天,监测春玉米苗期田间土壤温度和水分变化,测定春玉米产量并对产量构成因素进行分析,建立出苗率与土壤温度和水分多元线性回归数学模型.结果表明:春玉米出苗率与土壤温度和水分呈显著正相关.播种时土壤水分和土壤温度的差异显著影响成熟期籽粒产量.当土壤温度一定时,土壤体积含水率每增加1％,出苗率提高0.789％,出苗速率提高0.798％;当土壤体积含水率一定时,土壤温度每增加1℃,出苗率提高0.352％,出苗速率提高0.793％.松玉419在4月29日播种时产量最高,比正常播期(5月4日)产量提高6.66％,即每年4月底5月初,土壤平均温度在13.1～13.6,土壤体积含水率在13.1％～15.3％时播种最佳.土壤水分对春玉米出苗率影响最大,而土壤温度对春玉米出苗速率影响最大.

[目的]合理密植和施肥是提高雨养农业区作物产量和肥料利用效率的有效途径.我们研究了半湿润雨养黑土农业区玉米不同种植密度和施氮量及其互作对光能利用率和产量的影响,为进一步挖掘东北玉米产量潜力提供理论依据和数据支撑.[方法]于2017—2019年以郑单958?(ZD958)为供试品种进行了田间试验.试验采用裂区设计,种植密度为主区,分别为4.5×104株/hm2?(M4.5)、6.0?×104株/hm2?(M6.0)、7.5?×104株/hm2(M7.5)和9.0?×104株/hm2?(M9.0),施氮量为裂区,分别为N?120?kg/hm2?(N120)、180?kg/hm2?(N180)和240?kg/hm2(N240),各处理均设3次重复.分析了玉米光能利用率(LUE),玉米地上部干物质累积量、籽粒产量、净光合速率(Pn)和叶面积指数(LAI)等指标.[结果]年度间玉米产量、干物质量、LAI、净光合速率(Pn)和光能利用率(LUE)差异均达显著水平.2017、2018、2019年玉米的光能利用率(LUE)平均分别为1.58％、1.99％和2.20％.种植密度对玉米产量、干物质量、LAI、光合速率(Pn)和LUE的影响均显著(P<0.05),在密度M7.5处理下,LUE和平均产量最高(2.07％和12219?kg/hm2),在光合辐射较低年份(如2019年)可通过适当增加种植密度来提高玉米的光能利用率(LUE)和产量.施氮量对玉米干物质量和LAI有显著影响(P<0.05),LUE在N180处理下最高,平均为2.0％.密度与施氮量互作对玉米产量、干物质量、LAI、光合速率(Pn)无显著影响,但对LUE影响显著,以M7.5+N240处理LUE平均值最高(2.16％),且密度对光能利用率(LUE)的影响(9.93％)大于施氮量的影响(6.01％).[结论]在半湿润雨养黑土农业区,密度、密度与施氮量交互作用均显著影响玉米的光能利用率,密度的影响大于施氮量.适当增密(7.5×104株/hm2)和合理施氮量(N?180～240 kg/hm2)是实现玉米高产的重要措施.

以宏育236、翔玉998、加美2号为试验材料,田间设置6万、7万、8万、9万、10万株/hm2 5个种植密度和纯氮150、180、210,240、270 kg/hm2 5个氮肥施用量,研究种植密度与氮肥用量对玉米茎节干物质积累及抗压强度的影响,并与推倒强度进行相关性分析,为玉米密植抗倒机械化生产提供依据.结果表明,密度是影响茎节单位茎长干物重及压碎强度的主要因素,单位茎长干物重随密度增加表现为先升后降趋势,压碎强度随密度增加而降低.单位茎长干重同时受到氮肥的影响,密度与氮肥间存在正向互作效应,当密度大于8万株/hm2时不可逆地降低.第3～5茎节的干物质积累对玉米茎秆抗倒伏能力有显著影响.第3～5茎节单位茎长干物重与第3节压碎强度可作为玉米抗倒性能评价指标,在密植高产栽培管理中,要重视延长下部叶片功能期,增加下部茎节干物质重量.

果蝇作为重要的遗传学实验材料,传统上需要麻醉才能进行性状观察与性别鉴定,对初学者而言很难在有限的时间内完成观察和鉴定.果蝇永久制片的开发解决了这一问题.本文详细介绍了制作果蝇永久制片的方法与注意事项,并提出了果蝇制片在实验课中适用范围.利用果蝇永久制片,可实现在非麻醉条件下,长时间进行性状观察,准确掌握性别鉴定方法,操作简单,实用性强,为利用果蝇进行遗传规律验证实验打下良好基础.果蝇永久制片在大学遗传学与高中生物学实验教学中具有重要应用价值.

氮肥减施是减少环境压力,实现农业高产高效与绿色可持续发展的有效途径.为了评价玉米秸秆多年连续还田条件下,实现N肥减施的可行性,以连续多年秸秆还田试验地为试验条件,以普通农户氮肥用量(270 kg/hm2)为对照,分别设置氮肥减施1/9、2/9、1/3、4/9共4个量级水平,研究了不同氮肥减施对玉米的产量、收获指数以及氮肥利用的影响.结果表明:在氮肥减施2/9处理下,产量和生物量无显著降低,但显著提高了收获指数.氮肥减施对茎的氮浓度无显著影响,但氮肥减施1/3与4/9显著降低了籽粒的氮浓度以及茎和籽粒的氮吸收量.此外,随着氮肥减施量的增加,氮肥的偏生产力显著提高.综上,在氮肥减施2/9条件下,可充分协调玉米的产量与氮利用效率,为氮肥最佳减施处理.

遗传学是生命科学相关专业的一门重要的、理论与生产实践紧密联系的专业基础课程, 同时也是一门新知识、新技术层出不穷, 发展非常迅速的学科.为适应学科的发展和社会对创新性人才的需求, 本文分析了遗传学课程对学生创新能力培养的作用, 在遗传学教学过程中注重学生创新能力培养的改革举措.具体就培养学生的创新思维、转变教师的教学理念、激发学生的创新欲望、在科研实践中提升创新能力和更加科学合理的考核方式等多个方面进行了教学改革的探索和实践.

从品种布局、土壤耕作与施肥、气候、机械及土地流转5个方面人手,通过文献查阅、实地调查、委托调查、专家访谈、农户访谈、电话咨询等方式相结合,以吉林省为主要调查区域,并将其划分东、中、西部,对限制东北春玉米密植高产高效和机械化收获的关键因素进行详细分析.充分结合目前东北地区春玉米种植与收获过程中存在的种种问题,具体提出相应的解决对策,助推东北春玉米密植高产高效与全程机械化采收进程.

Root sampling methods, destructive excavation of monoliths (as reference method) and soil coring using auger, were compared for correlations and mean differences in root length density (RLD). Significant correlations between auger and monoliths methods were observed for RLD of maize roots in each depth interval (0.5198<=r<=0.7443, P < 0.01 at each depth), and when depths were pooled (r=0.692, P < 0.01). Linear relationships were also observed for faba within the 20 to 80 cm depth intervals. In contrast, there were no significant correlations observed in RLD between methods for barley or wheat at any depth. Overall, the average RLD from the soil depth of 100 cm for maize was 0.56 cm cm(-3) (0-4.48 cm cm(-3) range) in auger core, but only 0.37 cm cm(-3) (0 to 1.32 cm cm(-3) range) in monolith samples (F=20.08, P=0.0464). This indicates that RLD estimates will be higher when maize roots are sampled by the auger method than when monoliths are dug, particularly in the top 40 cm of soil. Average RLD did not vary between methods for wheat or barley (F=10.53, P=0.0833). It was, therefore, concluded that auger and monolith methods both yield reliable RLD data for fine root systems (e.g., barley and wheat). In contrast, RLDs of crops with coarser and taproots (e g, maize and faba bean) were likely overestimated by the auger core method. Thus, the monolith method is likely more suitable for crops with coarser and taproot systems. These results are partly benefited for field researchers in optimizing root sampling methods. (C) 2019 Friends Science Publishers

采用田间原位试验的方法研究玉米秸秆全量粉碎耕翻还田条件下,不同镇压强度(250、450、650 g/cm2)、播种深度(3、5、7 cm)以及起垄时期(秋起垄与春起垄)等耕作措施对玉米出苗率的影响.结果表明:起垄时期对出苗率无显著影响,播种深度与镇压强度对玉米出苗率影响分别达显著(P＜0.05)与极显著水平(P＜0.01),随着镇压强度的提高,玉米出苗率由80.6％提高到93.5％,而5 cm播种深度下出苗率显著高于3 cm与7 cm下玉米的出苗率,且播种深度和镇压强度交互作用极显著地影响玉米出苗率.在播种深度5 cm、镇压强度650 g/cm2时玉米出苗率最高,达到96.5％,为本试验条件下最佳耕作措施.