Comparison between Microwave Coherent and Incoherent Scattering Models in Corn Field

[Objective] The aim was to compare and analyze microwave coherent and incoherent scattering models in a corn field. [Method] In the research, based on a coherent scattering model （Stile）, we proposed a coherent scattering model exclusive for corn, in which, physical optics （PO） and infinite-length dielectric cylinder were used to calculate single-scattering matrices of corn leaves and stalks. In addition, coherent components produced from interaction among the scattering mechanisms were also considered and this coherent model was compared with the Michigan Mi- crowave Canopy Scattering （MIMICS） model. The measured data in a corn filed in Gongzhuling in Jilin Province were used as the input parameters of the coherent and incoherent models. We simulated backscattering coefficients of VV and HH po- larization at L and C bands and made a comparison between the simulation results. [Result] The simulation results at L-band were poor, which indicated that we could not find regularity at early growth stage of vegetation. In addition, comparisons be- tween coherent and incoherent scattering models proved that the coherence triggered by the scattering mechanism was small. [Conclusion] In the research, we analyzed differences between coherent and incoherent scattering models with change of incident angle, and further analysis on the differences with change of vegetation and soil needed to be made in future.

Association of host plant growth and weed occurrence with armyworm(Mythimna separata) damage in corn fields

To clarify association between armyworm（Mythimna separata） damage level and the corn growth and weed occurrence, we investigated corn plant height, stem diameter and vigor as well as weed coverage and biomass. The investigations were conducted at three locations of Shaanxi Province, China which were suffered seriously from armyworm. Significant correlations were found between the parameters analyzed. At stunted corn growth and presence of plenty of weeds, the armyworm damage tended to be heavy; oppositely, when corn grew well and weed density were low, armyworm harm was the minimal. Therefore, corn growing status and weed density can significantly affect armyworm damage level. Our results imply that promoting corn growth and timely removal of weeds are conducive to reducing armyworm occurrence.

Seed Health Status of Sweet Corn (Zea mays L. saccharata Sturt) from Five Areas in China and Effect on Field Seedling Emergence

The health status of 18 sweet corn (Zea mays L. saccharata Sturt) hybrids classified to two types, collected from five areas in China, was examined by PDA method, and factors influencing seed health and relationships between seed health and field seedling emergence were studied. Seventeen fungal genera were isolated and Fusarium was the most frequently isolated. There were significant differences both in incidence of Fusarium and in percentage of infected seeds among 18 hybrids. Research also showed that significant and consistent differences both in seed-borne fungal taxa and in percentage of infected seeds existed between two types of sweet corn. Sugar enhanced corn is more slightly infected than super sweet corn both in fungal taxa (13 and 16, respectively) and in percentage of infected seeds (62.0 and 79.2%, respectively). There were also significant differences both in seed-borne fungal taxa and in percentage of infected seeds among five areas. Seeds from South China were most severely infected, for there were 14 fungal genera detected and the percentage of infected seeds was highly 99.1% while those from Northwest China were slightly infected, for there were 10 fungal genera detected and the percentage of infected seeds was only 14.3%. Further research showed that there were significant negative correlations both between incidence of Fusarium and percentage of field seedling emergence and between percentage of infected seeds and percentage of field seedling emergence. Percentage of field seedling emergence could be estimated by regression equations built by regression analysis.

Effect of Sweet Corn Straw Returning to the Field on Soil Fertility, Yield and Benefit

It is an important way for realizing sustainable development of sweet corn production to stabilize and improve soil fertility of cultivated land in sweet corn production region.Through the test of sweet corn straw directly returning to the field after 6seasons for 3years,the results showed that continuous single application of chemical fertilizer is not conducive to the stability of soil fertility and yield improvement,and implementation of straw returning could receive fertility,improve soil acidic conditions,and enhance the yield of sweet corn.Compared with before the test,the single application of chemical fertilizer increased soil available phosphorus,while the contents of soil organic matter,available nitrogen and available potassium decreased by 1.08,1.18 and 2.47mg/kg respectively,and the soil pH decreased by 0.15.Under the same fertilizer conditions,organic matter contents of single and double-season straw returning increased by 0.71 and 1.29g/kg,available nitrogen increased by 17.15 and 28.27mg/kg,available phosphorus increased by 0.96 and 1.73mg/kg,available potassium increased by 2.41 and 5.92mg/kg,the soil pH increased by 0.16 and 0.2.Compared with the single application of chemical fertilizer,the average yields of single and double-season straw returning increased by 7.5%and 11.8%,and their average income increased by 87.3and 117.1yuan of per mu(667m^2)respectively.

新疆制种玉米生产机械化技术——种植与田间管理

新疆制种玉米在种植过程中,玉米父本和母本播种时间不同,通常情况下,制种玉米父本需要播种2次。制种玉米田间管理需要放苗、除草、中耕、间苗、去除杂株、去除玉米母本雄穗和去除玉米父本。在去除杂株、去除玉米母本雄穗和去除玉米父本环节,需要专用的农业机械,但是针对上述环节的专用农机具尚不成熟或没有相应的农机具,制约了新疆制种玉米种植技术水平的发展,影响了制种玉米种植收益。为此,应制定制种玉米种植技术规范对广大种植户进行技术培训,加快研制制种玉米种植专用农机具,政策引导制种玉米有序规范种植。

感应电场对普鲁兰酶解玉米淀粉结构性能和体外消化的影响

以玉米淀粉为研究对象,探讨磁感应电场对普鲁兰酶水解淀粉结构性能和体外消化的影响。结果显示,经过酶解和感应电场的处理,改性后玉米淀粉颗粒出现大量孔洞,偏光十字模糊,结晶区1 047 cm-1/1 022 cm-1升高,1 022 cm-1/995 cm-1降低,相对结晶度随着感应电压的增加而增加。直链淀粉相对含量呈现先上升后下降的趋势,当感应电压为125 V时,直链淀粉相对含量高达98.61%。溶解度和膨胀度随着施加感应电压的增强先降低再增加,硬度和内聚力呈先增加后减少的趋势。原玉米淀粉和处理淀粉的黏性随剪切速率增加而迅速减少。储存模量和损耗模量与直链淀粉的含量有一定关系。当感应电压为125 V时抗性淀粉相对含量高达62.46%。体外消化水解率和血糖指数呈现先减少后增加的趋势。本研究可为感应电场在改性淀粉的生产和开发方面提供理论参考。

1LF-5型液压翻转犁的设计与试验

为推动玉米秸秆还田保护性耕作农艺的发展,设计了一种集土壤耕作技术、玉米秸秆还田技术于一体的1LF-5型液压翻转犁,一次作业既翻转了土层、松碎了土壤,又可将土壤表层的玉米秸秆与作物残茬翻入土层下,形成隔层进行还田;同时,犁体受到突发外力冲击时,安全装置自动生效,使犁柱绕固定轴栓旋转,从而保护犁体与犁柱的安全。田间试验表明:1LF-5型液压翻转犁的平均耕作深度稳定为33.45cm,平整度为20mm,变异系数在3.166%~3.535%之间;在第1工况下,翻转犁的耕宽平均值为220.75cm,耕宽的变异系数范围为1.21%~1.71%;在第2工况下,翻转犁的耕宽平均值170.1cm,耕作宽度的变异系数范围为1.26%~1.68%;植被覆盖率平均值为89.97%,土垡破碎率为72.27%。机具满足国家标准GB/T14225对于耕作质量的各项要求,也满足翻耕农艺要求。

玉米秸秆堆腐还田对黑土区土壤性状的影响

本研究针对东北地区秋冬季节气候寒冷特点和秸秆堆腐还田的实际操作需求,开展秸秆堆腐还田试验。在秋季玉米收获之后进行田间堆腐试验,期间连续监测环境温度、降水、秸秆堆温度、秸秆失重率等指标。离田玉米秸秆经过腐熟后作为肥料还田,连续施用3年,检测土壤有机质、碱解氮、速效磷、速效钾、土壤孔隙度、土壤容重等指标。在基本农田和棚室保护地进行为期2年的应用试验。结果表明:120 d秸秆失重率达到31.53%。施用腐熟秸秆3年,土壤有机质提高了4.06~6.31 g/kg、土壤中碱解氮提高了15.08~27.35 mg/kg、速效磷提高了18.11~21.95 mg/kg、速效钾提高63.97~89.93 mg/kg;土壤容重降低了0.10~0.14 g/cm^(3)、土壤田间持水量提高了7.51%~9.24%(V/V)、土壤孔隙度提高了3.69%~5.27%(V/V),且差异显著(P≤0.05)。基本农田和棚室保护地应用试验中,速效养分与有机质有所增长,土壤容重与田间持水量变化显著。逐年施用腐熟秸秆对于提高土壤有机质含量、速效养分具有显著作用。同时,施用腐熟秸秆能够降低土壤容重,提高土壤孔隙度与田间持水量,改善土壤板结问题。腐熟秸秆在改良与保育黑土性质方面具有良好的作用。

等氮条件下施用不同有机肥对玉米田大型土壤动物种群的影响

为从土壤动物角度研究土壤改良和耕地质量提升,探究等氮条件下不同有机肥和化肥配施对玉米田大型土壤动物的影响,试验设定猪粪(处理3)、羊粪(处理4)、菌渣(处理5)、易腐垃圾(处理6)有机肥、化肥(处理2)和空白(处理1)共6个处理,对不同施肥处理不同土层的土壤环境及大型土壤动物的分布情况开展调查,并对其大型土壤动物多样性进行了分析。结果表明,在玉米田土壤中共捕获到膜翅目、蜘蛛目、半翅目和弹尾目等10个类群的大型动物,以膜翅目和蜘蛛目为优势类群。各处理组的Shannon-Wiener多样性指数从高到低依次为处理6、处理3、处理4、处理5、处理2和处理1。其中,易腐垃圾有机肥处理的Shannon-Wiener多样性指数和均匀度指数最高,猪粪有机肥处理次之。4种有机肥处理的Shannon-Wiener多样性指数均比纯化肥和空白处理高,可见有机肥料的施用增加了土壤含水量,提高了有机质及全氮含量,有利于土壤动物群落数量和多样性增加,有利于农业可持续发展。

基于EDEM-Fluent的玉米储藏立筒仓环流通风与纵向通风仿真分析

为解决立筒仓中纵向通风方式储粮效果不佳,在储粮机械通风过程中存在通风不均匀等问题,该研究结合纵向通风与横向通风的优点建立了环流通风仓模型,应用EDEM-Fluent流固热耦合方法,对相同工况下,储粮仓两种风道结构在机械通风时的速度场、温度场进行仿真对比分析。结果表明:环流通风速度均匀性指数为0.92,纵向通风速度均匀性指数为0.88,相同工况下环流通风气流在粮仓内分布更均匀。在温度场仿真分析中,纵向通风初期入风口附近区域粮堆温度呈梯度下降,明显低于初始温度,上层粮堆由纵向通风引起的热量传递不明显,受仓顶环境温度影响,粮面温度较粮堆内部低;环流通风初期,上层粮堆在环流通风影响下已经开始进行热量交换,产生温度梯度,通风结束后,纵向通风在粮层高度H=0.5 m处,温度维持26.85℃,H=0.8 m处温度降到27.85℃,整体平均温度降至24.77℃,环流通风仓在这两处温度分别为24.85和25.85℃,整体平均温度降至23.43℃,环流通风整体降温效果优于纵向通风;在颗粒温度场仿真分析中,相较于纵向通风,环流通风仓上下部颗粒温度相差较小,整体降温均匀。在不同通风形式下的粮仓各层温度变化规律分析中,不同高度的粮层,环流通风的粮堆温度均低于纵向通风,环流通风的粮堆温度下降更快,降温效果更好。整体结果表明,加装环流风道后立筒仓内粮堆降温效果明显优于纵向通风结构,研究结果为立筒仓风道优化,解决储粮通风不均问题提供重要依据。

射频联合热风加热对玉米籽粒中黄曲霉毒素B1降解及玉米品质的影响

为研究射频-热风联合处理玉米中的黄曲霉毒素B1(aflatoxin B1,AFB1)降解效果,分析不同初始水分质量分数(19.05%、22.25%、25.55%)、射频加热温度(55、65、75、85℃)和加热持续时间(10、15、20、25 min)对玉米籽粒中AFB1降解效果及玉米品质的影响。结果表明:射频-热风联合处理可有效降解AFB1,在高水分含量下,加热温度和时间一定,初始水分含量越高,AFB1残留量越高;初始水分含量一定,随温度增加和时间延长,AFB1残留量随之减少,且加热持续时间对降解效果的影响大于加热温度;射频-热风联合处理玉米籽粒过程中,对其品质有一定影响,随温度升高和时间延长,与对照组相比,蛋白质、脂肪含量无显著差异(P>0.05),黏度系数显著降低(P<0.05);低场核磁共振分析表明,射频加热过程中水分迁移效果明显,且水分迁移特性与玉米的糊化特性、蛋白质、脂肪含量显著相关(P<0.05)。

Synthesis of Southern Corn Rootworm Pheromone from S-Citronellol and Its Field Evaluation

Southern rootworm (Diabrotica undecimpunctata howardi) affects several plants such as soybean, sorghum, wheat, cucumber, alfalfa, cucurbits and it is most damaging to corn and peanuts. The pheromone based “attract and kill” strategy is one of the powerful ways to control pest population. To address our key objective of the practical utility of the synthetic pheromone, we have developed a simple synthetic strategy to produce gram scale southern corn rootworm pheromone in nine simple steps starting from S-Citronellol. The present strategy takes advantage of the existing chiral center of commercially available S-Citronellol. To get the basic carbon skeleton of the pheromone, the main step in the synthetic strategy is coupling of aliphatic units through Wittig reaction. The phosphonium salt from a non-functionalized aliphatic bromide followed by Wittig reaction improved the overall yield in the multistep synthesis of this pheromone. The large-scale production of pheromone enabled us to test it in the field.

玉米秸秆还田技术要点

秸秆还田技术的应用对农业资源再利用和改善生态环境具有积极意义。本文从玉米秸秆还田技术的基本情况、优势分析以及技术要点方面进行总结探析。玉米秸秆还田是将玉米秸秆粉碎后覆盖还田,该技术能够培肥地力,改善土壤理化性质,增强土壤中微生物活性,防治病虫草害,提高产量及效益。同时,本文提出了合理选择秸秆还田时机、把握秸秆粉碎长度、耙地深埋、控制秸秆还田量、土壤消毒以及防治病虫害发生等技术要点。为提高作物秸秆利用率,进一步推广玉米秸秆还田技术提供参考。

秸秆还田及蚯蚓活动对小麦-玉米轮作下土壤水分运移的影响

为探讨关中平原小麦-玉米水分高效利用的栽培技术方式,采用田间定点观测方法,研究秸秆还田+接种蚯蚓处理对土壤含水量的影响。设置CK(对照)、S_(1)(秸秆还田3000 kg·hm^(-2))、S_(2)(秸秆还田6000 kg·hm^(-2))、E(接种蚯蚓)、S_(1)E(秸秆还田3000 kg·hm^(-2)+接种蚯蚓)、S_(2)E(秸秆还田6000 kg·hm^(-2)+接种蚯蚓)共6个处理。结果表明:各处理较CK处理均提高了土壤含水量,S_(1)、S_(2)、E、S_(1)E、S_(2)E处理下土壤含水量分别增加0.21%~27.47%、0.43%~32.85%、1.00%~15.53%、3.25%~36.52%、2.97%~51.24%。CK、S_(1)、S_(2)、E、S_(1)E、S_(2)E处理下土壤含水量分别为15.51%、17.14%、17.66%、16.33%、17.94%、18.91%;S_(2)E处理土壤蓄水保水效果最佳,S_(2)、S_(1)处理次之,E处理效果最差。由小麦扬花期、收获期到玉米抽雄期、收获期,不同处理下0~100 cm土壤含水量整体呈增长趋势,最大均值在玉米收获期(20.60%),最小均值在玉米抽雄期(8.63%)。相比于CK处理,其余处理均扩大了高含水区范围,且接种蚯蚓处理下土壤高含水区范围大于未接种蚯蚓处理。对小麦-玉米生长期土壤含水量影响因素相关分析结果显示,土壤含水量与>0.25 mm的大团聚体、SOC含量、TN含量呈显著正相关关系(P<0.05),与0.053~0.25 mm、<0.053 mm的土壤团聚体、pH值、毛管孔隙呈显著负相关关系(P<0.05)。可见,秸秆还田与蚯蚓活动有利于增加土壤含水量,扩大深层高含水区,提高土壤蓄水能力,进而提高降水利用效率。

几种土壤封闭处理除草剂对大豆-玉米带状复合种植田杂草防效及安全性的影响

为了探明大豆-玉米带状复合种植模式下的有效化学除草技术,采用室内生测结合田间试验,通过土壤喷雾处理方法,调查除草剂720 g/L异丙甲草胺乳油、70%嗪草酮可湿性粉剂、75%噻吩磺隆水分散粒剂、80%唑嘧磺草胺水分散粒剂、41%氟噻草胺悬浮剂对大豆、玉米的安全性以及在田间的杂草防除效果。结果显示,唑嘧磺草胺、噻吩磺隆、嗪草酮与氟噻草胺、异丙甲草胺两两混用后,田间杂草药后30 d防效达87%以上,药后45 d防效达93%以上,持效期也相对较长。受环境影响,5种除草剂虽在室内试验表现出一定抑制作用,但田间各单剂混用后与对照的表现相差不大,说明对大豆、玉米安全。综上,异丙甲草胺、嗪草酮、噻吩磺隆、唑嘧磺草胺、氟噻草胺单用或混用,可在大豆-玉米带状复合种植田块中于大豆、玉米播种后1~2 d内进行土壤喷雾处理防除杂草。

冀东地区春玉米田苗前土壤封闭除草剂减量增效复配组合优选

为了优选适合冀东地区春玉米田苗前土壤封闭除草剂的减施增效复配组合,采用土壤喷雾的方式对苗前处理除草剂扑草净、乙草胺、二甲戊灵、莠去津、噻酮磺隆·异噁唑草酮进行了减量增效复配田间药效试验。结果表明,施药后第28天,扑草净1125 g/hm^(2)+乙草胺1125 mL/hm^(2)的复配组合对杂草的株防效最高,为84.20%;其次为二甲戊灵1500 mL/hm^(2)+莠去津1125 mL/hm^(2)和噻酮磺隆·异噁唑草酮375 mL/hm^(2)+用水量3‰“迈丝”,对杂草的株防效分别为80.80%和80.70%,3个处理间防效无显著差异。施药后第42天,扑草净1125 g/hm^(2)+乙草胺1125 mL/hm^(2)复配组合对杂草的株防效和鲜质量防效最高,分别为91.35%和95.88%,鲜质量防效显著高于其他施药处理。扑草净1125 g/hm^(2)+乙草胺1125 mL/hm^(2)的减量复配组合可作为冀东地区春玉米田苗前土壤封闭化学除草推广使用。

玉米秸秆还田技术应用现状及发展建议

玉米是我国主要农作物,玉米秸秆作为重要的可再生生物质资源,具有很高的利用价值。秸秆还田是现阶段秸秆综合利用的主要形式之一,秸秆还田技术应用能有效促进土壤肥沃、减少环境污染并提高农民收入。该文对玉米秸秆还田的现状和应用价值、注意事项进行了研究和探讨。结合现有秸秆还田技术提出对秸秆处理的方法,提出了玉米秸秆还田技术的发展建议,以期利用秸秆还田技术达到低成本、无害化保护黑土地资源的效果,对于农业可持续发展具有重要意义。

农业信息化技术在玉米田间管理中的应用

玉米种植过程中农业信息化技术与农机技术的融合对于提高玉米产量与品质具有积极促进作用。以农业机械化背景下的玉米种植田间管理为研究对象,分析了采用农业信息化相关技术的应用要点。采用物联网技术建立玉米种植田间管理系统,能对玉米生产全过程实施监测与控制,为农机运行与控制提供依据,实现品种选择、产量预测、精量播种、精准施肥、节水灌溉等多重功能,防范病虫害可能给玉米生长造成的影响。

玉米深松机械作业参数对作物产量和质量的影响研究

该文探讨玉米深松机械作业参数对作物产量和质量的影响。采用田间试验的方法,对不同深度、不同行距和不同深松频率的深松机械作业参数进行了比较。结果显示,深松机械作业可以明显提高玉米产量和品质。在深度方面,深度为30 cm的深松作业效果最佳;在行距方面,行距为70 cm的深松作业效果最佳;在深松频率方面,3年深松一次的效果最佳。因此,建议在实际生产中,根据土壤情况和农业生产特点选择适当的深松机械作业参数,以提高玉米的产量和品质。

麦-玉耕作秸秆混土还田模式下离散元参数标定

麦-玉一年两熟的江淮、黄淮地区秸秆混土还田保护性耕作模式,麦秸秆-土壤混合的种床缺乏准确的物料相互接触参数,阻碍了机械化玉米精密播种过程中关键部件、种粒、肥料与混合种床相互作用研究,进而制约了机具优化与改进。采用物理与EDEM离散元方法结合研究非连续体麦秸秆-土壤混合物之间相互作用,选用Bonding V2黏结模型搭建柔性麦秸秆段“元颗粒”,选取Hertz-Mindlin with JKR模型对一定湿度的土壤进行参数标定。首先,以圆桶提升麦秸秆和土壤种床混合物堆积角为响应值,采用Plackett-Burman筛选试验和最陡爬坡试验分别对显著影响因素从大到小排序和缩近最佳取值范围。利用Box-Behnken试验构建了显著影响因素与堆积角二阶回归模型,对显著因素交互项进行响应曲面分析,利用Design-Expert软件优化模型并以实测堆积角39.94°为目标响应值,计算得土壤JKR表面能0.500、土壤-秸秆动摩擦系数0.065 8、土壤-秸秆JKR表面能0.262及土壤-土壤动摩擦系数0.155,仿真验证误差1.08%,表明标定的接触模型参数可靠。该研究可为麦-玉保护性耕作模型下混合种床与机具精密播种相互作用研究提供参考和理论依据。