重庆市玉米耐密增产试验研究

2009—2011年连续3年对玉米不同品种、密度的试验研究表明,在重庆地区每667m2种植4000～4200株的高密度,较常规3000株密度增产10.75%～20.34%,并远远高于农民当前大面积生产产量,增密增产趋势明显。该研究结果进一步应证重庆市具有承载适当密植的温光资源条件。根据本试验研究结果,推荐将增密1000株/667m2和配套选用耐密品种作为重庆市当前玉米增产增效技术。     

不同耐密性玉米品种地上部与根系性状的协同效应

【目的】阐明不同玉米品种在增密种植条件下地上部性状和根系构型的协同响应,为耐密性玉米的遗传改良提供理论支撑。【方法】以我国18个主栽玉米品种为试材,设置2个种植密度(6万株/hm²和7.5万株/hm²),分别在吐丝期和成熟期测定14个地上部农艺性状和8个根系构型性状,利用方差分析与回归分析等统计方法解析耐密高产品种的地上地下协同关系。【结果】随着种植密度的增加,玉米单株地上部和根系生物量及籽粒产量等指标下降,群体地上部生物量和籽粒产量显著提高。根据两个种植密度下的群体产量,受试品种中6个被划分为高低密度下均高产的双高型(DH);3个品种为仅高密度下高产的高密高产型(HH);7个品种为高低密度下均低产的双低型(DL);2个品种为仅低密度下高产的低密高产型(HL),供试品种主要为双高型(DH)和双低型(DL)。在高密度下,DH品种比DL品种具有更多的吐丝前干物质累积量和更高的收获指数,DH品种在减少根系干重、节根数和根系宽度的同时,保持了较高的根系表面积与总根长。综合两个种植密度下地上部与根系性状对产量的贡献,发现吐丝期茎秆干物质、成熟期籽粒干物...     

云南多雨烟区增密减氮对烤烟产质量及养分利用率的调控效应

为明确增密减氮对烤烟产质量及肥料利用率的调控效应。以烤烟品种"云烟105"为材料,研究种植密度(13 890,15 150,16 665株/hm~2)和施氮水平(0,84,94.5,105 kg/hm~2)及其互作对烤烟产质量及养分利用效率的影响。结果表明:适度增密减氮能显著提高烤烟肥料利用率、产量和产值,使烟叶总糖、还原糖、钾含量显著升高,总氮、烟碱含量降低,对水溶性氯无显著影响,烟叶化学品质更加协调。烟叶化学成分协调性及烤烟氮磷钾利用率显著受年份、密度、施氮及年份×施氮、密度×施氮、年份×密度×施氮互作影响,其中施氮、密度及互作对烟叶化学成分含量效应分别为42.5%,27.3%,18.9%,而其对养分利用率的效应分别为38.2%,25.4%,23.8%。与当前烤烟种植模式相比,增密和减氮10%～20%组合对烤烟增产、提质和增效作用显著,最佳密度和施氮量分别为15 150株/hm~2和84.0～94.5 kg/hm~2。     

不同耐密性玉米品种的根系生长及其对种植密度的响应

根系形态和分布对土壤中养分和水分的吸收有重要影响。增加耐密性是现代玉米（Zea may L.）育种的主要方向,而耐密性与根系的关系尚了解不多。本文以70年代主推的2个不耐密型品种（中单2号与丹玉13）和2个当代耐密型现代品种（先玉335和郑单958）为材料,将田间试验和室内水培试验相结合,在3个密度水平下,研究了不同耐密性玉米品种的根系差异及其对种植密度的响应。结果表明,目前推广的耐密型品种的根系要小于不耐密的老品种。不同耐密性品种之间的差异主要表现在040 cm。随着密度的增加,根显著变小、变细。密度主要降低020 cm土层中的根系生长,对深层根系影响较小。先玉335和中单2的根系长度对密度的反应较弱,郑单958和丹玉13较强。这说明先玉335主要依靠其小根系适应高密度,而郑单958既依靠较小的根系,同时依靠较高的根系反应性适应高密度。     

浅谈玉米生产的限制因素与对策

1基本情况 “十一五”期间国家加快玉米生产的主要任务是“一增四改”,“一增”就是增加种植密度。根据各地推广的品种特性和生产条件,因地制宜地将现有品种的密度普遍增加500～1000株／667m^2。“四改”一是改种耐密品种,力争到2010年耐密品种的推广面积由目前的666．7万hm^2达到1333．4万hm^2。     

密度对春玉米生理成熟后倒伏变化的影响

晋中盆地热量资源丰富,后期可供春玉米立秆脱水时间充足,抗倒性是该区域实施春玉米机械粒收的关键因素。增密种植与立秆延期收获是机械粒收技术发展和推广的重要措施,而玉米生长后期倒伏是限制种植密度进一步提升的重要因素,如何合理选择种植密度同时兼顾高产和抗倒就成为该区域实施春玉米机械粒收技术面临的重要问题。为此于2017—2019年在山西省农业科学院东阳试验示范基地,以29个玉米主栽品种和已审定、待审定、有潜力的宜机收品种为材料,分析了春玉米3个种植密度(6.0万株·hm~(-2)、7.5万株·hm~(-2)和9.0万株·hm~(-2))下生理成熟后倒伏情况。结果表明,随着种植密度增加,春玉米生理成熟期平均倒折率分别为0.4%、1.2%和2.5%,生理成熟后平均倒折率呈显著(P0.05)增加,且每推迟10 d玉米倒折率分别平均增加0.2个、0.7个和1.5个百分点。根据拟合方程,以GB/T 21962—2008规定的玉米机械粒收条件倒折率小于5%为标准, 9.0万株·hm~(-2)仅可立秆至10月2日, 7.5万株·hm~(-2)和6.0万株·hm~(-2)可充分利用当地积温立秆脱水至11月。根据收获期产量和倒折率双向平均法, 3年都稳定表现出高产抗倒的品种为‘金科玉3306’(7.5万株·hm~(-2))、‘金科玉3306’(9.0万株·hm~(-2))、‘迪卡517’(7.5万株·hm~(-2))和‘华农887’(7.5万株·hm~(-2)),收获期平均产量为14 091.8kg·hm~(-2),平均倒折率为1.7%,可推荐为该区域春玉米适宜机械粒收的品种和密度。一般可根据降水年型、灌溉条件以及品种耐密性等,合理选择6.0万株·hm~(-2)或7.5万株·hm~(-2)两种种植密度,以实现高产抗倒,最终提高春玉米机械粒收产量和质量。     

八个新引玉米品种密植适应性评价试验

以渝单8号为对照筛选适宜重庆市璧山县生态下密植的高产高效玉米品种,试验在常规生产密度条件下增密500株/667 m2(即3000株/667 m2)开展研究。通过植株性状、抗病性、抗倒性、穗部产量构成性状以及实收产量等性状在密植下的综合对比分析,在引进的8个品种中筛选出4个增产品种,即渝单30、渝单35、重玉100、三峡玉6号。其中以渝单30增密增产优势最明显,产量较对照(渝单8号)增产8.42%,差异达到极显著水平。     

基于密度联网试验和Hybrid-Maize模型的内蒙古 玉米产量差和生产潜力评估

采用科学方法对内蒙古玉米产量差与生产潜力进行定量化研究,对合理规划内蒙古玉米增产途径及产业发展具有重要意义。本研究采用品种×密度联网试验和Hybrid-Maize模型模拟相结合的方法,利用2006年以来内蒙古各生态区历年高产攻关田的最高实测产量和各区域农户平均产量,对内蒙古全区和6大生态类型区的玉米产量差和生产潜力进行了系统分析。结果表明,各生态区的模拟产量、高产纪录、试验产量、农户产量皆表现为从东到西逐步提高。内蒙古玉米模拟产量潜力为14.9 t×hm~(-2),高产纪录产量为14.4 t×hm~(-2),试验产量为11.1 t×hm~(-2),农户产量分别实现了模拟产量潜力的49%、高产纪录产量的51%和试验产量的66%。基于模型模拟的产量差(YGM)、基于高产纪录的产量差(YGR)和基于试验产量的产量差(YGE)分别为7.5 t×hm~(-2)、7.0 t×hm~(-2)和3.8 t×hm~(-2)。基于YGE的短期生产潜力达3 525.2万t,是当前总产水平的1.6倍,短期增产潜力为1 191.9万t。其中,内蒙古东部的呼伦贝尔、兴安盟、通辽、赤峰4盟市对全区的增产贡献率将达61%,西部的呼和浩特市、巴彦淖尔市为16%。造成较大YGE主要原因是栽培管理措施不当,缩小YGE需要针对限制各生态区玉米增产的实际问题,通过栽培技术综合改良、技术简化和技术入户来逐步实现。     

深松对春玉米根系形态特征和生理特性的影响

为研究深松对春玉米根系形态特征和生理特性的影响。以郑单958和先玉335为供试品种,设旋耕(R)、深松加旋耕(S+R)2个处理,于2012和2013年进行田间试验。结果表明,深松可以显著提高2个品种春玉米实测产量(P0.05)、春玉米乳熟期和完熟期根干质量(P0.05)且40 cm以下土层尤为明显。2个品种春玉米30 cm土层处的株、行间根幅均表现为S+R小于R处理,其中行间根幅的差异达到了显著水平(P0.05),单株根条数和比根长均表现为S+R显著高于R处理(P0.05)。乳熟期60 cm以下土层根系活力S+R高于R处理且随着土层的加深差异逐渐增大,超氧化物歧化酶和过氧物酶活性在吐丝期和乳熟期各土层S+R均高于R处理,而丙二醛含量低于旋耕处理。深松促进根系特别是下层根系干质量的增加,增加根系纵深分布,春玉米根系重心下移,并保持较高的生理活性,是其能够增产的重要原因。该文可为春玉米高产栽培提供依据。     

玉米宽行双株增密高产栽培技术示范初报

2015年在五峰县开展"玉米宽行双株增密高产栽培技术"示范,宽等行双株种植玉米有利于通风透光,与CK比较千粒质量显著增加,产量提高,产量854.2~859.2 kg/667 m~2,比CK的811.3 kg/667 m~2增产42.9~47.9 kg/667 m~2,增长5.3%~5.9%。     

有关间混作研究中几个问题的探讨

本文从间混作系统的整体出发，运用生态学原理论述了间混作研究中密度、施肥量、两种作物之间的比例关系、产量的表示方法和总产的计算问题，并运用粗密度、生态密度和标准化产量概念阐明了间混作实占面积与整体面积产量以及总产的计算问题，将行比与作物比有机地结合在一起，从而能够更加完整地反映出间混作的空间排列和群体大小。     

Earthworm dynamics and soil physical properties in the first three years of no-till management

Earthworms are often referred to as ecosystem engineers due to their ability to alter the soil environment. Since earthworms influence a wide range of critical chemical and physical soil properties it is important to understand how their populations are impacted by soil management. Earthworms were sampled during the spring and summer of 2001, 2002, and 2003 from conventional tillage (CT) and no-till (NT) plots established in 2000. Although there was a strong trend for higher earthworm density in NT plots in 2001 (p = 0.08) and 2002 (p = 0.19), statistically significant differences were not detected between tillage treatments until 2003 (p = 0.04) when mean earthworm density was 37.7 individuals m⁻² in CT and 149.9 individuals m⁻² in NT during spring and 17.1 individuals m⁻² in CT and 58.4 individuals m⁻² in NT in summer. A high mortality rate between spring and summer, combined with greater cocoon production under NT suggests that the earthworm population turns over rapidly in NT plots. Data also suggest that adverse soil environmental conditions will limit earthworm density in these dryland agroecosystems. Despite significantly higher earthworm density after three years of NT management, soil bulk density, saturated hydraulic conductivity, and aggregate stability of the 0.5- to 1-mm size fraction were not different between the two tillage treatments. The apparent lack of impact of reduced disturbance and increased earthworm density on soil physical properties may be due to the short time this soil has been under NT management, limited seasonal earthworm activity due to environmental conditions, or differences in the scale at which soil physical properties have been affected after three years of NT management and the scale at which our measurements were made.     

Visual structure assessment and mechanical soil properties of re‐cultivated soils made up of loess

Re‐cultivated soils (previously piled soils used as the final surface cover in renovation of open cast mine sites) are particularly susceptible to compaction, which is why a simple estimate of mechanical strength is necessary for land management. In this study, therefore, precompression stress (?6 kPa matric potential) was determined for a total of 20 soil layers from 9 repeatedly cultivated areas of arable land in North Rhine–Westphalia (Germany), along with the aggregate density/dry bulk density ratio (as a measure of density heterogeneity) and air capacity (as a soil ecological parameter). These results are contrasted with the determination of packing density. Packing density (PD) is an integrated parameter that combines various properties (aggregate size, cohesion of the soil structure, root distribution, biogenic macropores and aggregate arrangement) and is assessed visually in the field. Packing density levels range between 1 (very loose soil) and 5 (very highly compacted). There is a strongly negative relationship between packing density and both the aggregate density/dry bulk density ratio and air capacity. Conversely, mechanical precompression stress increases with packing density. Ranges of the individual parameters can be assigned to each of the packing density levels. Packing density level 3 represents an optimization with regard to mechanical soil stability whilst maintaining minimum air capacity requirements (5–8 Vol.‐%).     

Arbuscular mycorrhizal development,glomalin‐related soil protein (GRSP) content,and rhizospheric phosphatase activitiy in citrus orchards under different types of soil management

The arbuscular mycorrhizal (AM) status with respect to colonization of different AM structures in the citrus roots, spore density and hyphal length density, GRSP content, and phosphatase activity in the citrus rhizosphere were investigated in the orchards at Zigui county of the Three Gorges Region, S China. Four soil managements, no‐tillage and natural grass (NN), no‐tillage and sod culture (NS), half‐tillage and film mulching (HT), and clean‐tillage (CT) were employed in those citrus orchards. Our survey showed heavy AM colonization (36%–89%), indicating a high AM dependency of citrus in our experimental orchards. The colonization of different AM structures, spore density, hyphal length density, GRSP content, and phosphatase activity varied greatly between the no‐tillage and tillage citrus orchards. The highest colonization of different AM structures except the ratio of root length with vesicles (RLV), spore density, hyphal length density, GRSP content, and phosphatase activity was observed in the no‐tillage orchards, and the lowest was found in the tillage orchards. A cluster analysis based on the similarity in AM status, GRSP content, and phosphatase activity showed similarities between the NS citrus orchards and the NN citrus orchards. The data presented here demonstrate that tillage reduced the total AM colonization (RLT), spore density, hyphal length density, GRSP content, and phosphatase activity, while those were recovered in the no‐tillage citrus orchards. So, we propose that no‐tillage and planting grass is an effective way for citrus production and improvement of soil quality in orchards of the study area.     

黄土丘陵区4种典型植物根系分布特征及对土壤分离速率的影响

以黄土丘陵区4种典型植物种群(狼牙刺、白羊草、铁杆蒿、达乌里胡枝子)为研究对象,采用野外采样、室内模拟试验与分析相结合的方法,对0—30cm土层的各径级根系密度参数(根长密度、根体积密度、根表面积密度)与土壤理化性质、土壤分离速率间的关系进行了研究。结果表明:(1)4种植物的根系径级主要集中在0D≤1.0mm之间,86%~93%的根长和46%~61%的根表面积分布在此范围内,且根系径级越大,根系各密度参数越小;(2)4种植物各径级根密度参数对土壤理化性质(容重、有机质、团聚体)的影响各不相同;狼牙刺根系直径为0D≤1.0mm的根密度参数与土壤容重、有机质含量呈极显著相关;铁杆蒿在0D≤1.0mm径级的根密度参数与土壤容重呈极显著负相关,与土壤有机质含量呈极显著正相关,所有径级的根密度参数与土壤团聚体均呈显著正相关;白羊草在0D≤5.0mm径级区间内的根可有效改善土壤的容重,在0D≤2.0mm径级根密度参数与土壤有机质、团聚体呈显著正相关;达乌里胡枝子在3.0D≤5.0mm径级的根对土壤容重影响显著,直径D1.0mm的根对土壤团聚体有显著的影响;(3)土壤分离速率与根系各密度参数呈负相关。除达乌里胡枝子外,其他3种植物在0.0D≤1.0mm径级上根密度参数与土壤分离速率均呈极显著负相关。     

黄土区草被生长过程中土壤抗冲性及其与影响因素的关系

采用室内盆栽与原状土冲刷相结合的方法,设置了裸地对照(CK)、低种植密度黑麦草(H1)和高种植密度黑麦草(H2)3种处理,对3种处理在不同生长阶段的土壤理化性质和根系变化进行研究,分析了黄土区草被生长过程中土壤抗冲性及其与影响因素的相关关系。结果表明:(1)处理CK的容重、有机质含量和水稳性团聚体在4个生长阶段波动变化,但变化范围较小;随生长周期的延长,H1和H2处理的土壤容重呈下降趋势,有机质含量、水稳性团聚体、根表面积密度(RSAD,root surface area density)和根生物量密度(RWD,root weight density)呈增加趋势;在4个生长阶段,H1和H2处理各根径的RSAD表现为随根系径级的增大而减小。(2)CK和H2处理的土壤抗冲指数(ASI,anti-scourability index)在4个生长阶段无显著性变化;H1处理的ASI随生长时间的延长表现为逐渐增加的趋势,且在第16周,对ASI的影响最显著。(3)ASI与土壤容重呈幂函数递减关系,与有机质含量、水稳性团聚体呈幂函数递增关系,与RSAD、RWD之间均呈指数递增函数关系。(4)ASI与容重、水稳性团聚体、1.0~2.0,2.0~5.0,5mm径级的RSAD之间均无显著差异,与有机质含量、RSAD及RWD呈显著正相关(p0.05),与1mm径级的RSAD呈极显著正相关(p0.01)。     

基于SOTER的河北省土壤有机碳、氮密度的空间分布

本文在河北省土壤与地形体数据库基础上,计算了该省不同土壤组合的土壤有机碳和氮的密度,应用GIS技术分析了河北省土壤有机碳和氮密度的空间分布特征。结果表明:河北省土壤的平均有机碳密度为10.83kgm-3,平均氮密度为1070.96gm-3,C/N比为9.99;该省的土壤有机碳和氮密度的空间分布均呈现:不同类型土壤组合的有机碳和氮密度均随着纬度的增加而逐渐增加,而且其分布受气候、土壤特性、土地利用方式、植被特性以及人类干扰程度等的影响。     

不同根系构型草本与灌木复合对土壤饱和导水率的影响因素分析及模拟

[目的] 探究不同根系构型草本与灌木复合时的根土性质的差异对土壤饱和导水率的影响,并综合考虑根系和土壤性质建立估算土壤饱和导水率的经验方程,为黄土高原植被恢复后的水文模型建立提供理论参考。[方法] 选取不同根系构型草本与灌木的混合样地,分别为柠条锦鸡儿加冰草(须根系)和柠条锦鸡儿加铁杆蒿(直根系)。采用双环刀法测定不同样地土壤饱和导水率。[结果] 样地类型和土层深度对土壤饱和导水率的影响达到显著水平,两者对土壤饱和导水率影响的因子贡献率分别为26%和52%。直根系铁杆蒿与柠条锦鸡儿混合样地的土壤饱和导水率高于须根系冰草与柠条锦鸡儿混合样地,并且不同样地的土壤饱和导水率随土层深度的增加均表现出降低的趋势。根长密度、团聚体以及土壤容重能够较好地模拟土壤饱和导水率,其拟合精度R²可以达到0.86。[结论] 直根系草本与灌木复合时较须根系草本与灌木复合相比具有更高的饱和导水率。在不同样地中,根长密度、团聚体以及土壤容重是影响饱和导水率的主要因素。     

Comparison of critical limits for crop plant growth based on different indicators for the state of soil compaction

Soil compaction affects physical soil condition, in particular aeration, soil strength, and water availability and has adverse effects on plant growth. Bulk density is the most frequently used indicator to describe the state of compaction of a soil. However, this parameter lacks a direct functional relationship with plant growth. Various indicators have been proposed to simultaneously characterize the state of compaction of agricultural soil and its suitability for plant growth. This paper examines and compares the critical limits for crop plant growth based on three of these indicators: packing density, least limiting water range, and S parameter (the latter is the slope of the soil water‐retention curve in the inflexion point). In a first step, we reviewed the literature for published optimum and limiting values of bulk density and found that these values were highly dependent on clay and silt content. Converting them into corresponding values of packing density (composite index of bulk density and clay content), a value of 1.70 was found to effectively distinguish between optimum and limiting soil conditions for plant growth. In a second step, the packing density of 59 soil horizons sampled in N Switzerland was compared with the least limiting water range and the S parameter of these soil horizons (both determined by means of pedotransfer functions taken from the literature). A linear relationship between the three parameters was found, which allowed for a comparison of the published critical limits for plant growth based on these parameters. The critical limits of the three indicators, which had been postulated independently of each other in the literature, were found to agree well with each other. This means that all of them could equally be used to describe the compaction state of a soil and its physical suitability for plant growth. However, the proposed critical limits of packing density, least limiting water range, and S parameter still need further validation by field studies relating plant growth to soil compaction.     

Determination of Soil Aggregate Porosity Using the Modified Water Saturation Method

The need to find a simple method for measuring soil aggregate porosity(φ) is justified by the growing interest of researchers in this important parameter of soil physical status. The aim of this study was to present a simple method(AM) for estimating the totalφ of a single soil aggregate. In this case, soil aggregate φ was calculated as the quotient between the pore volume, estimated from the weight of the aggregate saturated with ethanol, and the total volume(V_T) of aggregate, calculated from the particle density and dry aggregate weight. The V_T estimated with AM was compared with the corresponding volume measured with the photogrammetry(PHM) technique using soil aggregates of 8–16 mm in diameter and collected from three different tillage systems: conventional tillage(CT), reduced tillage(RT), and no tillage(NT). Next, the AM was used to study the effects of the tillage system on soil aggregateφ. Although a strong relationship(R~2= 0.99, P 0.000 1) between aggregate V_T measured with PHM and that estimated with AM was obtained, AM tended to underestimate aggregate V_T with an average deviation of 2.85%. This difference may be due to ethanol evaporation during the first 10 s before the ethanol-saturated aggregate was weighed. The use of AM to determine the effects of different tillage systems on aggregate φ showed that this method was sensitive to detect significant differences among the tillage treatments.The results showed that AM could be an accurate, simple, and inexpensive alternative to estimate φ of a single soil aggregate.