Effects of Continuous Nitrogen Application on Grain Yield and Nitrogen Uptake and Utilization in Winter Wheat-Summer Maize Rotation System

[Objective] This study aimed to achieve high yield and stable yield of win- ter wheat-summer maize rotation system and provide basis for rational application of nitrogen fertilizer. [Method] Effects of continuous nitrogen application on grain yield, economic profit, nitrogen uptake and utilization efficiency, and soil inorganic nitrogen accumulation in winter wheat-summer maize rotation system were investigated. [Re- sult] Nitrogen application could significantly increase the y（eld of the winter wheat- summer maize rotation system, which increased by 17.76%-30.32% and 22.24%- 46.63% in two rotation cycles, respectively. The yield of the winter wheat-summer maize rotation system was the maximum in two rotation cycles with nitrogen appli- cation amount of 660.0 kg/hm2, which reached respectively 23 391.19 and 23 444.35 kg/hm2, the yield and economic benefit were the highest, the nitrogen fertilizer use efficiency was 22.2% and 30.7%, the agronomic efficiency was 8.3 and 11.3 kg/kg. However, the nitrogen fertilizer use efficiency and agronomic efficiency between ni- trogen application amount of 540.0 and 660.0 kg/hm2 showed no significant differ- ence. After two rotation cycles, inorganic nitrogen accumulation in 0-40 cm soil with nitrogen application amount of 540.0 kg/hm2 was almost equal to that before experi- ment. [Conclusion] Under the experimental conditions, comprehensively considering the grain yield, economic profit, nitrogen fertilizer efficiency and soil inorganic nitro- gen balance, the optimal nitrogen application amount was 625.3-660.0 kg/hm2 in high-yield winter wheat-summer maize rotation system.

Fate of ^(15)N-Labeled Urea Under a Winter Wheat-Summer Maize Rotation on the North China Plain

A field experiment was conducted to investigate the fate of ^15N-labeled urea and its residual effect under the winter wheat （Triticum aestivum L.） and summer maize （Zea mays L.） rotation system on the North China Plain. Compared to a conventional application rate of 360 kg N ha^-1 （N360）, a reduced rate of 120 kg N ha^-1 （N120） led to a significant increase （P 〈 0.05） in wheat yield and no significant differences were found for maize. However, in the 0-100 cm soil profile at harvest, compared with N360, N120 led to significant decreases （P 〈 0.05） of percent residual N and percent unaccounted-for N, which possibly reflected losses from the managed system. Of the residual fertilizer N in the soil profile, 25.6%-44.7% and 20.7%-38.2% for N120 and N360, respectively, were in the organic N pool, whereas 0.3%-3.0% and 11.2%-24.4%, correspondingly, were in the nitrate pool, indicating a higher potential for leaching loss associated with application at the conventional rate. Recovery of residual N in the soil profile by succeeding crops was less than 7.5% of the applied N. For N120, total soil N balance was negative; however, there was still considerable mineral N （NH4^＋-N and NO3^--N） in the soil profile after harvest. Therefore, N120 could be considered ngronomically acceptable in the short run, but for long-term sustainability, the N rate should be recommended based on a soil mineral N test and a plant tissue nitrate test to maintain the soil fertility.

Cover Crops as Affecting Soil Chemical and Physical Properties and Development of Upland Rice and Soybean Cultivated in Rotation

Cover crops can provide changes in soil chemical and physical properties, which could allow a sustainable development of soybean and upland rice rotation in Brazilian Cerrado. The objective of this study was to determine the effects of cover crops(cultivated in the offseason) in the soybean-upland rice rotation(cultivated in the summer season) on the soil chemical and physical properties, yield components and grain yield of the cash crops. The experimental design was a randomized block design in factorial scheme 4 × 2 with six replications. Treatments were composed by four cover crops: fallow, millet(Pennisetum glaucum) + Crotalaria ochroleuca, millet + pigeon pea(Cajanus cajans), and millet + pigeon pea + Urochola ruziziensis in the offseason with one or two cycles of cover crops, with rice(Oryza sativa)or soybean(Glycine max) in the summer season. Cover crops alone provided no changes in soil chemical properties. However, the rotation cover crops/cash crops/cover crops/cash crops reduced p H, Al and H + Al and increased Ca, Mg, K and Fe contents in the soil. The cover crops millet + pigeon pea and millet + pigeon pea + U. ruziziensis improved soil physical properties in relation to fallow,especially in the 0–0.10 m soil layer. In spite of the improvement of the soil physical properties after two years of rotation with cover crops and cash crops, the soil physical quality was still below the recommended level, showing values of macroporosity, S index and soil aeration capacity lower than 0.10 m3/m3, 0.035 and 0.34, respectively. Upland rice production was higher under mixtures of cover crops than under fallow, mainly because of soil physical changes done by these mixtures of cover crops.Soybean grain yield was similar under all cover crops tested, but was higher after the rotation cover crops/upland rice/cover crops than after only one cycle of cover crops.

Soybean seed protein, oil, fatty acids, and mineral composition as influenced by soybean-corn rotation

Effects of crop rotation on soybean (Glycine max (L) Merr.) seed composition have not been well investigated. Therefore, the objective of this study was to investigate the effects of soybean-corn (Zea mays L.) rotations on seed protein, oil, and fatty acids composition on soybean. Soybeans were grown at Stoneville, MS, from 2005 to 2008 in five different scheduled cropping sequences. In 2007, following three years of rotation with corn, seed oleic acid percentage was significantly higher in any crop rotation than continuous soybean. The increase of oleic fatty acid ranged from 61 to 68% in 2007, and from 27 to 51% in 2008, depending on the rotation. The increase of oleic acid was accompanied by significant increases in seed concentrations of phosphorus (P), iron (Fe), and boron (B). In 2007, the increase of P ranged from 60 to 75%, Fe from 70 to 72%, and B from 34 to 69%. In 2008, the increase of P ranged from 82 to 106%, Fe from 32 to 84%, and B from 62 to 77%. Continuous soybean had higher linoleic:oleic ratio and linoleic: palmitic + stearic + oleic ratio, indicating that relative quantity of linoleic acid decreased in rotated crops. The total production of protein, oil, stearic and oleic fatty acids was the lowest in continuous soybean. The total production of palmitic acid was inconsistent across years. The results show that soybean- corn rotation affects seed composition by consistently increasing seed oleic fatty acid, P, Fe, and B concentrations. Higher oleic acid, unsaturated fatty acid, is desirable for oil stability and long-shelf storage. The mechanisms of how these nutrients are involved are not yet understood.

基于虚拟数据和旋转目标检测分析的大豆豆荚表型参数测量方法

为解决传统大豆考种过程中人工测量大豆豆荚表型参数耗时费力的问题以及现有的自动化测量方式存在的人工数据标注需求量大、环境适应能力弱、计算代价高等问题,本研究提出一种基于虚拟数据集生成和旋转目标检测分析的豆荚关键表型参数自动化测量方法,重点关注荚长和荚宽的测量。该方法基于YOLOv7-tiny提出一种改进的豆荚检测模型(CSL-YOLOv7-tiny),通过引入环形平滑标签使模型获得对旋转目标的检测能力,提升对无序摆放的狭长豆荚目标检测的质量。为避免人工标注训练数据,采用虚拟图像生成方法得到含标注信息的虚拟豆荚数据集和虚拟硬币与豆荚混合数据集。利用迁移学习策略,将模型从虚拟豆荚数据集迁移至虚拟硬币与豆荚混合数据集,积累模型对豆荚特征的提取能力。设计一种基于K-均值聚类的后处理方法,对检测到的旋转边界框进行分析,得到荚长和荚宽,以减少拍摄环境差异带来的测量误差。试验结果表明,在无任何训练数据标注的条件下,使用虚拟图像训练的CSL-YOLOv7-tiny对硬币和豆荚目标检测的最优mAP_(0.50)和mAP_(0.50∶0.95)分别达到了99.3%和78.0%,其模型大小和推理时间分别仅为12.92 MB和12.5 ms,荚长和荚宽测量的决定系数(R^(2))分别达到了0.94和0.86,与实际测量均值分别仅相差0.42 mm和0.02 mm。此外,通过对本研究提出的方法进行对比分析,验证了其在模型训练、轻量化部署以及不同考种环境适应能力上的优势。研究结果可为大豆豆荚表型参数的自动化、智能化测量系统的研发提供参考,为加速优质高产大豆的选育进程提供支撑。

秸秆还田和施肥对冬小麦-夏大豆轮作系统培肥与生产效益的影响

为探明秸秆还田和化肥施用对冬小麦-夏大豆轮作系统土壤培肥和生产效益的影响,于2020-2022年在关中平原开展田间定位试验,设置秸秆不还田不施肥(S0F0)、秸秆不还田常规施肥(S0F1)、秸秆还田配合常规施肥(S1F1)和秸秆还田配合减量施肥(S1F0.8)4个处理。利用静态暗箱-气相色谱法监测土壤N_(2)O排放通量,综合分析土壤养分、作物产量和土壤N_(2)O排放,明确秸秆还田配施化肥在土壤培肥、增产减排方面的效应。结果表明,秸秆还田和施肥通过显著提高土壤有机质(SOM)、全氮(TN)、全磷(TP)、硝态氮(NO_(3)^(-)-N)、铵态氮(NH_(4)^(+)-N)、速效磷(AP)含量来促进土壤培肥。与S0F0相比,S1F0.8和S1F1处理提高土壤综合肥力314.24%~317.12%、330.58%~384.98%;S1F0.8和S1F1处理显著提高冬小麦产量80.29%~101.25%、82.50%~107.66%,提高夏大豆产量25.31%~34.72%、36.93%~45.20%;S0F1、S1F0.8、S1F1均显著增加土壤N_(2)O累积排放量和种植系统温室气体排放强度,但S1F0.8较S0F1、S1F1处理显著降低土壤N_(2)O累积排放量和种植系统温室气体排放强度;S1F0.8和S1F1处理提高生产效益75.09%~75.88%、67.54%~114.23%。综上,秸秆还田配合常规施肥(S1F1)是关中平原麦-豆轮作系统土壤培肥的有效方式;但依照国家降低化肥施用量的要求来说,秸秆还田配合减量施肥(S1F0.8)是关中平原麦-豆轮作系统增产、减排、提高收益的推荐方式。

麦季不同施磷量对麦玉和麦豆轮作体系作物产量及磷效率的影响

[目的]为研究麦季不同施磷量对陕西关中地区不同轮作体系作物产量和磷肥效率的影响,明确实现不同轮作体系作物高产高效的适宜麦季磷肥施用量。[方法]以麦玉和麦豆2个轮作体系为研究对象,设置0,75,150,225,300 kg/hm^(2)5个施磷(P_(2)O_(5))水平,分析2021-2022年和2022-2023年轮作周年作物产量、磷肥利用效率、土壤有效磷及其与施磷量之间的关系。[结果]与不施磷处理(0 kg/hm^(2))相比,试验2年仅麦季施磷处理显著增加麦玉和麦豆轮作体系小麦、玉米、大豆和周年产量(p<0.05),且轮作周年产量和磷肥效率均达到较高水平。2个轮作体系的周年产量均在施磷150 kg/hm^(2)处理最高,麦玉轮作体系显著高于施磷75 kg/hm^(2)处理(p<0.05),但麦豆轮作与施磷75 kg/hm^(2)处理间差异不显著;麦玉和麦豆轮作体系获得最高小麦产量的土壤有效磷分别为20.07,16.15 mg/kg。2个轮作体系的磷肥农学效率、磷肥偏生产力、磷肥回收效率、磷效率指数(PEI)均随施磷量的增加而降低;施磷75 kg/hm^(2)麦玉和麦豆轮作体系的PEI分别为施磷150 kg/hm^(2)处理的1.24,2.02倍,麦豆的PEI降低更显著。综合考虑粮食安全、环境安全和肥料利用率,以95%的小麦最高产量为实际目标,对应的麦玉和麦豆轮作体系施磷量分别为115,95 kg/hm^(2),可实现磷肥回收效率及较低的磷盈余,保证麦玉和麦豆轮作体系周年产量分别达到最大产量的96.23%和95.43%;麦豆轮作体系具有较低的施磷量需求。[结论]对不同轮作体系应从作物丰产、肥料高效利用和基于零盈余的管理政策考虑,进行合理的磷肥施用,以在满足作物-土壤磷养分的协调供应、保证作物高产的同时,提高磷效率。

根内根孢囊霉对正茬和迎茬大豆生物量的影响

本研究旨在探究根内根孢囊霉(Rhizophagus intraradices)在缓解大豆迎茬障碍和提高大豆生物量方面的效应。以‘黑农48’品种的大豆为对象,通过湿筛倾析-蔗糖离心法、碱解离-酸性品红染色法以及直接测量法,分别对AM真菌孢子密度、侵染率及大豆生物量进行了测定。结果显示,正茬大豆田的根际土壤中孢子密度是迎茬的2.2倍。在自然土壤条件下,接种R.intraradices的正茬与迎茬土壤中的大豆植株,其根系AM真菌侵染率和生物量均显著高于未接种处理组,其中根长最为显著,分别提高了31.60%和33.57%。在迎茬土壤中接种R.intraradices菌剂的大豆生物量与正茬土壤中未接种处理组的接近。在相同接菌处理条件下,灭菌土壤中的大豆植株根系AM真菌侵染率和生物量均低于自然土壤。本研究这些发现为缓解大豆迎茬障碍和提升大豆产量提供了重要的理论依据。

“稻-豆-油”三熟制水旱轮作绿色高效栽培技术

为提高农民种植效益,稳定粮油生产,本研究充分利用地域优势和作物品种优势,通过多年的实验示范,总结集成了“早稻-鲜食秋大豆-油菜”三熟制水旱轮作绿色高效栽培模式。该模式不仅实现了粮食绿色安全生产和稳粮增粮,而且大幅提高了土地产出率,有效促进了农业增效、农民增收,是符合现代农业发展方向的高效生产技术模式。

不同覆盖及耕作措施对黑土区坡耕地土壤养分时空变化特征及作物产量的影响

为探究不同覆盖及耕作措施对黑土区坡耕地米-豆轮作农田土壤养分时空变化特征及作物产量的影响机制,于2022—2023年进行田间试验,设置顺坡碎秆均匀覆盖(SM),横坡碎秆均匀覆盖(CM)、顺坡覆盖作物(SC)和传统耕作(CK)4个处理,分析不同覆盖及耕作措施下土壤养分含量随生育时期和土层深度的变化趋势以及作物产量表现,明确不同覆盖及耕作措施下土壤硝态氮(NO_(3)^(-)-N)、铵态氮(NH_(4)^(+)-N)、速效磷(AP)、速效钾(AK)含量与作物产量之间的相关关系。结果表明:随作物生育时期的推进,各处理土壤AP含量呈先增加后降低的变化趋势,土壤AK含量呈逐渐减小的变化趋势;各处理土壤NH_(4)^(+)-N、NO_(3)^(-)-N、AP和AK含量随土层加深整体上呈逐渐减小的趋势。各处理的作物干物质量和产量较CK分别显著提升3.29%~11.96%和4.29%~14.77%;除2022年0~20 cm和20~40 cm土层土壤NH_(4)^(+)-N含量外,其余各土层土壤养分含量与作物产量均呈显著正相关关系(P<0.05),土壤AK含量对作物产量的影响程度更高。

麻豆轮作对作物农艺性状及产量的影响

为探索适合黑龙江地区推广的耕地轮作制度,本试验对汉麻、大豆进行连作和轮作处理,分析不同处理对大豆、汉麻农艺性状、产量及经济效益的影响。结果表明,轮作提高了大豆的株高、茎粗、主茎节数、有效节数、单株有效荚数、单株重、单株茎重、单株荚重、单株荚皮重、单株粒数、单株粒重和百粒重,以及汉麻的株高、茎粗、分枝高、分枝数、单株粒数、单株粒重和千粒重,降低了大豆的底荚高和单株瘪荚数。相关性分析结果表明,大豆除底荚高和单株瘪荚数与产量呈负相关,其余农艺性状与产量均呈正相关;汉麻的株高、单株粒数与产量呈明显正相关(P<0.01)。轮作提高了大豆、汉麻产量和产值,净收益比连作分别增加了1877.95和2636.40元/hm^(2)。

Contribution of Promiscuous Soybean （Glycine max L.） to Upland Rice-based Cropping Systems in West Africa

A two-year on-farm study was carried out at Eglime in the moist savanna （MS） and Ouake in the dry savanna （DS） of Benin to evaluate the contribution of inoculation of dual-purpose soybean varieties to grain yield of upland NERICA rice fertilized with low N level. In 2005, four dual-purpose, promiscuous soybean varieties （cv. TGx1440-IE; TG×1448-2E; TG×1019-2EB; and TG×1844-18E）, and a popular improved variety （cv. Jupiter） were sown in 12 farmer fields with and without Bradyrhizobium japonicum inoculation. There was also land which was left fallow that acted as the control. In 2006, upland interspecific rice （NERICA 1） was sown in all the plots and supplied with 15 kg N haL. Dry matter yield, N accumulation, and net N-balance were significantly enhanced by over 40% with inoculation of cv. TG× 1844-18E than non-inoculation in the DS in comparison to other cultivars. There were no significant effects of inoculation of previous soybean cultivars on soybean grain yield and on the succeeding NERICA rice yield. Averaged over inoculation, previous cv. TG× 1019-2EB plots supplied with only 15 kg N hal gave the highest grain yield, more than twice the yield of control plots in the DS, possibly because of significant production of higher tillers, panicles and harvest index than the other cultivars; and it could be recommended for upland rice-based system for NERICA production.

玉豆轮作下黑土区轮耕模式对土壤坚实度及玉米产量的影响

土壤轮耕有利于改善土壤理化性质、提高土壤结构稳定性、促进增产增收。为探寻适宜东北黑土区玉豆轮作田长期生产轮耕模式,于黑龙江省哈尔滨市香坊区设置4种轮耕模式:翻耕/深松/翻耕(PSP)、旋耕/深松/旋耕(RSR)、免耕/深松/免耕(NSN)、免耕覆秸/深松/免耕覆秸(SSS)(均在秸秆全量还田条件下处理)。分析不同轮耕模式对土壤坚实度、玉米各时期长势及产量的影响。结果表明,①SSS轮耕模式可有效改善土壤结构,0~80 cm土层土壤坚实度低于其他处理13.4%~22.3%,且各土层之间变化较为平缓。②SSS轮耕处理下,玉米在中、后期生长最优,株高显著高于其他处理7.1%~11.3%,茎粗显著高于PSP、RSR处理10.3%、11.6%。③SSS轮耕处理显著提高作物产量,平均产量高达11033.45 kg·hm^(-2)。综上,从黑土资源长期保护角度考虑,SSS轮耕模式为适宜黑土区玉米/大豆轮作田最佳轮耕模式,可为东北黑土垄作区蓄水保墒耕作技术体系构建提供理论依据。

多样化种植对土壤团聚体组成及其有机碳和全氮含量的影响

【目的】阐明东北黑土区禾本科与豆科作物多样化种植模式下土壤团聚体组成及其碳氮分布特征,为促进黑土地用养结合型种植制度优化提供理论依据与技术指导。【方法】田间试验于2016—2020年在中国农业科学院作物科学研究所公主岭试验站进行,设置玉米大豆间作(M/S)、玉米大豆轮作(M-S)、玉米花生间作(M/P)和玉米花生轮作(M-P)等多样化种植模式,以玉米连作(CM)常规种植模式为对照。2020年作物收获后采集0—20和20—40 cm土层土壤样品,分析多样化种植模式对土壤团聚体及其有机碳、全氮含量的影响。【结果】多样化种植有利于增加0—20和20—40 cm土层水稳性大团聚体(>0.25 mm)含量,降低黏粉粒(<0.053 mm)含量,4种多样化种植模式的土壤团聚体平均重量直径和平均几何直径均显著高于CM处理(P<0.05)。M/S和M-S处理0—20 cm土层>0.25 mm土壤团聚体比例分别比CM处理高17.6%和13.4%,M/S、M-S和M-P处理20—40 cm土层>0.25 mm土壤团聚体比例则分别比CM处理高10.4%、8.3%和10.5%。多样化种植增加了土壤大团聚体中有机碳和全氮含量,0—20 cm土层,M/S、M-S、M/P和M-P处理>2 mm土壤团聚体有机碳含量分别比CM处理高20.7%、24.3%、18.8%和17.8%;0—20 cm土层,M-S、M/P和M-P处理>2 mm土壤团聚体全氮含量分别比CM处理高13.0%、16.8%和14.8%。M-S和M/P处理0—20 cm土层>2 mm土壤团聚体有机碳和全氮对土壤总有机碳和全氮贡献率高于CM处理,而M/S和M-S处理<0.053 mm土壤团聚体有机碳和全氮对总有机碳和全氮的贡献率则低于CM处理。【结论】东北黑土区多样化种植提高了土壤大团聚体含量,降低了黏粉粒含量,增加了土壤团聚体稳定性及有机碳和全氮含量,有利于促进农田土壤碳氮固持。

Long-Term Impacts of Cover Crops, Chicken Litter, and Crop Rotations on Soil Health in No-Till Systems

Identification of management practices that can improve soil health is critical to improving the sustainability of soybean [Glycine max (L.) Merr.] production. The objective of this study was to examine the long-term effects of continuous soybean, corn-soybean, and soybean-cotton rotations with chicken litter and cover crops (hairy vetch, wheat, fallow) on soil health parameters, including nutrient accumulation and soil organic matter dynamics under a split plot design. The depth intervals of soil sampling were 0 - 15, 15 - 30, 30 - 60, and 60 - 90 cm. Chicken litter resulted in 62.1% and 32.8% higher water extractable organic soil N content than fallow and wheat, respectively, in the surface 0 - 15 cm of soil only. However, there was no significant difference in 1-day Solvita respiration, water extractable organic C, C/N ratio, health score, moisture, earthworm, organic matter, pH, or CEC of soil among fallow, hairy vetch, chicken litter, and wheat regardless of soil depth. Unexpectedly, annual application of chicken litter at 4.4 Mg ha−1 as an N source or growing a winter-season cover crop such as hairy vetch or wheat for continuous 16 years did not significantly increase soil organic matter or water extractable organic soil C. Annual application of chicken litter at 4.4 metric tons (Mg) ha–1 for 16 years increased soil nitrate-nitrogen (NO3−-N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) contents by 92%, 400%, 134%, 20%, 43%, 206%, and 430% in 0 - 15 cm depth compared with their initial soil values, respectively, extracted with Haney H3A-2 (2 g L–1 lithium citrate + 0.6 g L–1 citric acid + 0.4 g L–1 malic acid + 0.4 g L–1 oxalic acid) solution. The increases enhanced soil supply of these nutrients to following crops, but also increased the risks of losing them to the environment. Hairy vetch caused higher H3A extracted soil manganese (Mn) content than fallow and chicken litter in 0 - 60 cm. There was no significant difference in 1-day Solvita respiration, water extractable organic C and N, health score, moisture, organic matter, pH, CEC, or population of earthworm of soil among continuous soybean, corn-soybean, and soybean-cotton in any soil depth. Another major finding of this study was that continuous soybean exerted no adverse effect on soil health relative to the commonly used corn (Zea mays L.)-soybean and soybean-cotton (Gossypium hirsutum L.) rotations under no-tillage after 16 years. To mitigate the risks of nutrient runoff and leaching from long-term chicken litter application, we recommend reducing litter application rates and integrating cover crops into crop rotations to enhance nutrient cycling and reduce environmental impacts.

薯豆轮作模式下不同种衣剂对大豆农艺性状及产量的影响

为指导薯豆轮作模式下的大豆生产,选用3种种衣剂,采用田间对比试验方法,以不包衣和连作处理为对照,研究不同种衣剂对轮作大豆农艺性状及产量的影响。结果表明,薯豆轮作方式下3种种衣剂应用效果优于豆豆连作,大豆种子包衣促进了大豆植株生长和发育,使株高、茎粗、节间数、单株有效结荚数、百粒重和产量增加,底荚高度降低,能促进早结荚,使植株重心降低可抗倒伏,同时也促进了根瘤的发生,且对大豆根腐病防治效果明显。其中使用复合微生物菌剂拌种处理大豆的根瘤数最多,防治大豆根腐病效果最好,促进了大豆植株的生长发育,植株粗壮,增加了有效结荚数和产量;精甲·咯菌腈包衣处理的收获株数最多,但对根腐病防治效果最差,发病率最高;阿维·多·福化学药剂处理大豆有效结荚数、百粒重和产量最高,增产效果最好。

黑龙江省三江平原玉米-大豆轮作模式下田间杂草分布与防除

[目的]为了高效防除轮作条件下的农田杂草,该文研究了轮作条件下田间杂草的分布。[方法]通过2年对黑龙江萝北县的2块玉米-大豆、大豆-玉米轮作地块进行跟踪调查。[结果]同一村落不同地块间杂草种类不同,但各地块均是稗草为发生基数最多的杂草,同时发现,大豆地轮作为玉米地,除个别难防杂草外,杂草的发生多数会减轻;玉米地轮作为大豆田,阔叶杂草明显减少,稗草及问荆有所增加,其他杂草变化不大。鸭跖草、藜和问荆均是相对难防的田间杂草。[结论]防治措施如下:首先土壤封闭处理,用二元复配制剂(乙草胺或异丙甲草胺+噻酚磺隆或异辛酯)、或者三元复配制剂(乙草胺或异丙甲草胺+噻酚磺隆+异辛酯)、或者采用乙二嗪复配制剂;其次苗后茎叶处理,大豆田用异噁草松+烯草酮+氟磺胺草醚于大豆2~3片复叶期进行处理,玉米田用烟嘧莠或烟硝莠进行茎叶处理。进一步防除鸭跖草,可用氯酯磺草胺+氟磺胺草醚进行叶面处理。在问荆已出苗、大豆未出苗时用草甘膦防除问荆。

弱光性对玉米间作下春大豆表型及产量性状影响的研究

发掘耐荫大豆种质资源及指导耐荫性大豆品种(系)育种研究,设置自然荫蔽弱光条件下玉米与大豆间作试验,对宁夏灌区15份春大豆品种(系)进行耐荫性筛选研究,分析大豆表型及产量性状。结果表明,不同春大豆品种(系)的单株有效分枝数、单株分枝数的变异系数较大,分别为47.1%、35.4%;主茎节数、节间长度、荚粒数的变异系数较小,分别为10.0%、8.5%、8.0%。相关分析表明,大豆单株产量与株高、单株有效荚数、单株粒数呈极显著正相关,与荚粒数呈显著正相关,与百粒重、结荚初期(R3-R4)茎叶鲜重呈负相关,说明株高在适宜范围内,大豆产量随着单株有效荚数、单株粒数、荚粒数的增加而增加,但是大豆籽粒变小、百粒重下降,结荚初期(R3-R4)茎叶茂盛也会影响大豆产量。PCA分析表明,大豆品种(系)的多样性表现明显,前4个主成分累计贡献率达83.6%。聚类分析表明,15份春大豆品种(系)可以聚为4大类群。第Ⅰ类群和第Ⅱ类群的Ⅱ-Ⅰ亚群的4个品种(系),虽然植株偏高,但是单株粒数较多、单株产量较高,生产上可以通过肥水管控、化控等技术措施,控制大豆植株旺长,保证较多的单株有效荚数、单株粒数,增加百粒重,提高单株产量;第Ⅲ类群和第Ⅳ类群结荚初期茎叶鲜重较高,为153.0~191.6 g,建议该类群大豆品种(系)与青贮玉米间作,收获青贮饲料,增加蛋白质含量,提升青贮饲料品质。建议通过“株高因子、荚粒因子、分枝因子、茎叶鲜重因子”特征值选择适合间作套种的春大豆品种(系),增加大豆产量;不能直接在生产上应用的优异性状种质,可以作为亲本材料进行间接利用,以培育出适宜玉米-大豆间作的中间材料或新品种(系)。针对不同类群大豆品种(系)特点,通过肥水管控、化控及不同种植方式等措施来提高大豆产量。

不同玉米大豆间作行比对大豆光合特性及产量的影响

为研究适合东北黑土区玉米大豆间作行比,促进玉米大豆间作模式推广应用,本研究以玉米大豆间作系统为主要研究对象,设置玉米单作(M)、大豆单作(S)、玉米大豆行比2∶4间作(M2S4)、玉米大豆行比4∶4间作(M4S4)和玉米大豆行比4∶6间作(M4S6)处理,分析不同间作行比对大豆株高及干物质积累、光合特性相关指标、产量及经济产值分析的影响。结果表明:间作显著增加了大豆株高,降低了干物质量,同时,随着玉米条带数的降低及大豆条带数的增加,光合参数Gs和Tr与单作处理之间呈显著性差异,而Ci则呈现相反的变化趋势。4∶4间作行比(M4S4)处理具有较好的间作优势,土地当量比为1.26,在考虑了政府补贴后,间作复合经济产值显著高于各单作处理,其中,M4S4处理最具有增收潜力。综上,M4S4模式为东北黑土区最佳玉米大豆间作配置方式。

豆米轮作对春玉米土壤固氮细菌群落结构及多样性的影响

为探明大豆-玉米轮作对土壤固氮细菌的影响,以玉米连作为对照(MMM),以nif-H基因为指示,采用高通量测序技术,分析大豆-玉米2年轮作周期(MSM)和大豆-玉米-玉米3年轮作周期(SMM)下土壤固氮细菌群落结构及多样性。结果表明:大豆-玉米轮作下0~20、20~40 cm土层土壤有机质、全氮、碱解氮、铵态氮和硝态氮均显著增加。固氮细菌的Chao1指数和ACE指数在0~20、20~40 cm土层均为轮作高于对照,轮作下MSM显著高于SMM;Shannon指数和Simpson指数在0~20 cm土层轮作显著高于MMM;20~40 cm土层MSM显著高于MMM。在门水平上,MSM和SMM的0~20、20~40 cm土层变形菌门的相对丰度均高于MMM。在属水平上,2个轮作类型0~20 cm土层的慢生根瘤菌属、弗兰克氏菌属和纤毛菌属相对丰度显著较高;20~40 cm土层慢生根瘤菌属、伪食酸菌属、地杆菌属和固氮弧菌属相对丰度显著较高;MSM 0~20、20~40 cm土层慢生根瘤菌属、甲基孢囊菌属和固氮弧菌属较SMM均提高。方差分析表明,固氮细菌丰度指数(Chao1和ACE指数)与有机质、碱解氮和硝态氮的含量均呈显著正相关关系,慢生根瘤菌属的丰度与有机质、全氮和铵态氮的含量呈极显著正相关。综上,大豆-玉米轮作土壤养分较高是提高土壤固氮菌丰度和改变群落结构的重要因素,其中大豆-玉米2年周期下的固氮细菌丰度较高;大豆-玉米轮作可以增加土壤中具有高固氮效率和多功能的有益微生物类群。