Agronomic management options to enhance adoption of maize–common bean–common bean sequential intercropping in southern Ethiopia

Journal of Crop Science and Biotechnology - Achieving food security is a prime strategic goal for many developing countries where subsistence smallholder farming is dominant. It is crucial to study...     

Long-term effects of lime and phosphogypsum application on tropical no-till soybean–oat–sorghum rotation and soil chemical properties

Root growth, nutrition and crop yield can be affected by soil chemical modifications caused by superficial limestone and phosphogypsum application in a no-till system. Using this approach, this study was conducted in southeastern Brazil, continuing an experiment that has been on-going since 2002 with the objective of evaluating the residual effects of the surface application of lime and phosphogypsum on the soil chemical characteristics and the root growth, nutrition and yield of soybean, black oat and sorghum in a dry winter region cultivated in 2008/2009 and 2009/2010. The experimental design was a randomized block with 4 replications. The treatments were applied in November 2004 and were as follows: original conditions, limestone application (2000 kg ha⁻¹), phosphogypsum application (2100 kg ha⁻¹), and limestone (2000 kg ha⁻¹) + phosphogypsum (2100 kg ha⁻¹) application. Superficial liming with or without phosphogypsum reduced the surface and subsurface soil acidity 5 years after application in the no-till system. The movement of Ca²⁺ and Mg²⁺ from the surface layer into the subsoil over time was evident. The phosphogypsum application associated with liming increased the Ca²⁺ levels throughout the soil profile. Liming maintained high levels of Mg²⁺ throughout the soil profile with or without phosphogypsum application. The organic matter content increased with liming with or without phosphogypsum, indicating that in the long term, these practices can increase the C accumulation. Phosphogypsum application had a residual effect on the SO₄-S levels, and high sulphate concentrations were observed in the subsoil after 5 years. Superficial liming improved crop nutrition and, when associated with phosphogypsum, increased Ca absorption by soybean and sorghum, as reflected in the increased yields of these crops.     

Decoding Australia's China threat narrative during 2016–2021

Australia–China relations began to sour in 2016, and the China threat narrative began to dominate since then. Unlike previous studies which either use a qualitative approach or cross-sectional dataset for empirical analysis, this study creatively creates high-frequency weekly and monthly time series datasets using the Google Trends search results during January 2016–February 2021. Based on a series of time series modellings, this study examines the roles of various actors, including China's own policies, the Australian Strategic Policy Institute and Clive Hamilton, various factors, including Chinese purchase of Australian housing, Chinese investment in Australia, Chinese students in Australia and China's rise and various media outlets, including the Australian Broadcasting Corporation, Australian Financial Review, Sydney Morning Herald, Daily Telegraph and Herald Sun, in contributing to Australia's China threat narrative. This study makes significant contributions to academia in methods by bringing a new quantitative approach to international relations studies and to policy-makers as well by quantifying the roles of various actors, factors and media outlets in Australia's China policy debate.     

Ultimate Strength of Tube–gusset Connections With Ribbed Plate

The experiments were carried out to investigate the behavior and strength of tube–gusset connections with 1/4 annular ribbed plate.Based on the FEM, the strength of tube–gusset connections with different thin wall, different width and thickness of ribbed plate and modes of ribbed plate was analyzed.The calculation method of ultimate strength were proposed.It is found that the thickness of tube and the width and thickness of ribbed plate have evident influence on the strength of tube–gusset connections with ribbed plate with the conditions of tube and ribbed plate.     

稻–麦轮作下9000kg hm~(–2)产量水平扬麦20的群体质量及花后光合特征

在稻麦两熟制条件下,于2010—2011和2011—2012年度,通过氮肥施用量、施用时期及比例的调控,建立了扬麦20不同产量水平群体,比较≥9000 kg hm–2群体(P1)与9000 kg hm–2群体(P2)的产量构成、群体质量及花后光合特征,为稻茬小麦大面积高产提供理论依据和技术支撑。P1较P2群体产量高约10%,每穗粒数高约5.5%,差异显著,但两群体的穗数和千粒重差异不显著。P1群体的穗数、穗粒数和千粒重分别为482~538万hm–2、47~49粒和34~39 g。籽粒产量与孕穗和开花期叶面积指数(LAI)及花后LAI衰减率和光合势呈抛物线关系,与乳熟期LAI、粒(重)/叶比和群体生长率呈显著线性正相关。两年度试验结果表明P1群体具有以下特征,孕穗期、开花期和乳熟期的LAI分别为6.5~7.0、5.0~6.0和4.0~4.5;粒(数)/叶比为0.37~0.39,粒(重)/叶比为13.5~14.5;花后LAI衰减率、群体生长率、光合势和净同化率分别为0.13~0.15 d–1、19~20 g m–2 d–1、103×104~118×104 m2 d hm–2和9~11 g m–2 d–1。花后21d和28 d,剑叶SPAD值、净光合速率、丙二醛(MDA)含量及3种抗氧化酶(CAT、POD和SOD)活性与产量相关性均达极显著水平。研究表明,稻–麦轮作体系中,扬麦20达到9000 kg hm–2产量水平的栽培技术关键点是获得适宜穗数的基础上,主攻每穗粒数与千粒重的协调增加,使群体在花前具有较高的光合面积和光合速率,花后光合面积衰减速率低,维持较高的光合面积,从而充分积累花后光合物质,在适宜库容基础上保障对库充实的需求。     

2005–2019年江苏省冬小麦品种的性状分析

进一步了解江苏省冬小麦产量及主要农艺性状的演变规律,为江苏省冬小麦育种和生产提供借鉴。本研究对2005—2019年江苏省审定的109个小麦品种进行产量、品质与抗病性分析。结果表明,江苏省审定的小麦品种平均产量呈逐年递增趋势,年增产量为134.43 kg/hm²;穗数、穗粒数和千粒重呈逐年增长趋势,但增长幅度较小。主要农艺性状与产量的相关程度为穗数>千粒重,呈正相关;株高>穗粒数,呈负相关;产量三要素之间的偏相关均为正值,偏相关程度表现为穗数>穗粒数>千粒重;审定品种中有27个品种的容重、蛋白质和湿面筋含量达到中筋小麦品质标准,有15个小麦品种达到强筋标准,有54.12%的小麦品种的湿面筋含量低于中筋小麦品质标准,下一步应把提高湿面筋含量作为提高小麦品质育种的主攻方向。在审定的小麦品种中,没有可以兼抗赤霉病、纹枯病和白粉病3种病害的品种,兼抗赤霉病和白粉病的品种为‘淮麦21’、‘宁麦17’、‘镇麦9号’、‘宁麦18’、‘扬麦21’和‘扬江麦586’。江苏省小麦品种产量的提高应在保持适宜穗粒数的基础上,增加穗数,提高千粒重,同时进一步引进新的抗病、优质种质资源,以培育高产、优质、多抗的小麦新品种。     

The nuclear–cytoplasmic interaction controls carotenoid content in wheat

In greenhouse studies of three alloplasmic wheat series, plant height, flowering date and yield per plant were least affected when the native cytoplasm was replaced by donor cytoplasm of the Triticum–Aegilops complex than when replaced by Hordeum chilense cytoplasm. On the other hand, significant differences for seed lutein content were found between euplasmic controls and their respective alloplasmic lines in all the alloplasmic lines studied, underscoring the important role of the cytoplasm to determine the seed carotenoid content. Both T. aestivum subesp. macha and Ae. squarrosa cytoplasms increased the lutein content. They may be the most useful sources of cytoplasmic variability for broadening the genetic diversity of wheat for seed carotenoid content since both cytoplasm types do not produce any detrimental effect on agronomic traits, as previously reported by other researchers. These findings demonstrate the role of the nuclear × cytoplasm interaction in the accumulation of carotenoids in wheat.     

All lives matter. An analysis of internationals' living conditions in Seoul,Korea, using an extended image–satisfaction–loyalty mechanism

We indirectly analyze the residential environment for long-staying internationals in Seoul, Korea, by extending the image–satisfaction–loyalty mechanism widely used in tourism, specifically by examining the internationals' satisfaction and loyalty. We consider residential difficulties, sociodemographics, and survey years along with image as exogenous variables and evaluate satisfaction not only in terms of its absolute but also its relative level, which is the difference between absolute satisfaction (AS) and previous expectation. Tourism studies have measured loyalty using individuals' intention to recommend to another and their own revisit intention, but we evaluate the revisit intention with place attachment/hometown perception, which is more suitable for long-staying residents. The variables are measured with 2016–2018 data from an annual quality of life survey for Seoul residents (n = 5279 individuals) and analyzed with structural equation modeling. Our results show that the conventionally used AS is associated only with recommendation intention, but the relative satisfaction (RS) both with recommendation intention and hometown perception. Regarding the exogenous variables, AS is substantially affected by image and RS is somewhat strongly influenced by residential difficulties. However, image is the principal determinant of loyalty level, whether recommendation intention or hometown perception. These findings confirm the applicability of the image–satisfaction–loyalty mechanism not only to short-staying inbound tourists but also to long-staying international residents.     

镉污染稻区油菜–中稻替代双季稻种植的可行性研究

为了探讨镉污染稻区油菜-中稻替代双季稻种植的可行性,在湖南省湘潭县中度镉污染稻田开展大田试验,研究了油菜-中稻与双季稻模式下的作物生育进程、产量、经济效益与镉含量。结果表明,双季稻、油菜-中稻均能在10月20日前成熟;双季稻早、晚稻产量分别为5233.7和6298.3kg/hm²,油菜和中稻产量分别为1875.5和7531.0kg/hm²,中稻产量较早、晚稻产量分别提高43.9%和19.6%;与双季稻模式相比,油菜-中稻模式成本降低13.5%,产值提高2.1%,纯收入提高42.6%,总纯收入与劳动力比值升高38.5%;早、中、晚稻根、茎、叶和籽粒等器官镉含量差异明显,均表现为晚稻>中稻>早稻的趋势;糙米镉含量在0.43~0.82mg/kg之间,油菜籽镉含量为0.11mg/kg。综合种植季节、产量、经济效益和籽粒镉含量来看,油菜-中稻模式可作为镉污染双季稻区替代双季稻的种植模式。     

江淮地区稻–麦周年产量差及其与资源利用关系

江淮地区是我国水稻和小麦重要的生产基地,明确该地区不同产量水平之间的差异特征及形成机制,探索区域粮食生产的限制因子,可为缩减江淮地区周年产量差的技术途径提供科学依据和参考。本研究以稻–麦周年生产体系为研究对象,定量分析不同产量水平田块之间的产量差与气候影响因素。结果表明,江淮地区水稻、小麦及周年农户水平与试验水平和高产纪录间存在显著的产量差,分别为3315.9、1537.5、4645.6 kg hm–2和7498.6、3977.9、9840.9 kg hm^–2。水稻、小麦及周年农户水平较试验水平还有46.2%、29.7%和37.3%的增产潜力,较高产纪录还有104.5%、77.0%和79.0%的增产潜力。每穗粒数是造成水稻产量差的主要因子,穗数和每穗粒数是造成小麦产量差的主要因子。与农户水平相比,水稻试验水平和高产纪录的穗粒数分别增加30.4%和116.1%;小麦试验水平和高产纪录的穗数和每穗粒数平均分别增加40.9%、70.0%和21.8%、19.6%。缩小产量差水稻主要依赖于增加每穗粒数,小麦靠穗数和每穗粒数的协同提高。生育期累积辐射和积温较低是导致水稻产量差异的主要气候因素,而生育期降雨过多是导致小麦产量差异的主要气候因素。根据研究提出了“强稻稳麦”是提升江淮地区周年粮食生产的有效途径。     

豆科–燕麦间作对作物光合特性及籽粒产量的影响

为进一步揭示豆科燕麦间作体系中作物产量优势的光合机制,设置燕麦单作、大豆单作、花生单作、大豆燕麦间作和花生燕麦间作试验,在不施氮肥的条件下,调查大豆、花生同燕麦的产量、功能叶片相对叶绿素含量(SPAD)及光合特性。结果表明,与单作相比,大豆–燕麦和花生–燕麦间作优势明显,土地当量比(LER)分别为1.41~1.63和1.31~1.52。同大豆间作的燕麦除单株粒重及千粒重外,其他各产量构成因子均增加;同花生间作的燕麦各产量构成因子均高于单作燕麦,其中小穗数、穗粒数、单株粒重与单作相比差异显著;间作提高了大豆各产量构成因子,但降低了花生的结荚数及单株粒重。间作提高了燕麦的叶绿素含量和净光合速率,改变了叶绿素构成,使燕麦衰老延缓;间作对大豆的相对叶绿素含量及净光合速率均无显著影响;在燕麦孕穗后期至抽穗期,间作花生净光合速率显著高于单作。在不施氮肥的条件下,间作体系均明显优于单作,其中燕麦花生间作体系显著促进了燕麦的生长发育,大豆燕麦间作体系对燕麦、大豆均有一定促进作用。     

冬小麦–夏玉米高产模式周年气候资源分配与利用特征研究

探明周年产量20,000kghm–2以上冬小麦–夏玉米种植模式周年气候资源分配与利用特征,并建立资源优化配置定量指标,为进一步提升黄淮海该模式周年产量潜力和气候资源利用效率提供理论依据,具有重要意义。本研究利用2006—2010年黄淮海区9个高产点共45个田间试验的数据,定量分析了冬小麦–夏玉米模式高产形成与季节间光温水资源分配的关系。结果表明,三省9个试验点冬小麦–夏玉米均实现了周年20,000kghm–2以上高产,但区域间差异较大,河南和山东小麦产量最高,山东夏玉米产量最高,河南和山东周年产量分别高于河北16.9%和21.5%。产量的变化主要由光温水分配差异造成,河南和山东小麦季积温量在1924.2～2608.0°C和降雨量小于201.1mm范围时产量均高于河北,山东玉米季辐射量在2168.5～2953.8 MJ m–2、积温量小于2990.7°C和降水量小于591.3 mm范围时产量均高于河南和河北。然而省份间冬小麦–夏玉米模式季节间热量资源分配率和分配比值相对固定,即小麦季和玉米季积温分配率分别为43%和57%,两季间积温比值为0.7,这是该区当前生产和生态条件下冬小麦–夏玉米模式季节间资源合理配置的定量标准。在不增加任何投入的前提下依据该定量指标来指导黄淮海不同生态区冬小麦–夏玉米种植模式的资源优化配置,对促进黄淮海该种植模式可持续发展具有重要意义。     

普通小麦–卵穗山羊草种质对菲利普孢囊线虫的抗性

菲利普孢囊线虫(Heterodera filipjevi)是我国黄淮麦区新发现的一种病原线虫,但在小麦属中缺乏有效抗源。为从小麦近缘种属中发掘抗病资源,采用室内接种平均单株雌虫鉴定法和相对抗病指数法,从34份卵穗山羊草(Aegilops geniculata Roth)材料中筛选出6份抗H.filipjevi的种质材料,其中PI542187表现高抗,PI564186、PI573396、PI374365、PI361880和PI374365表现抗病。对中国春–卵穗山羊草染色体附加系抗性鉴定,发现卵穗山羊草7U g和5M g附加系的单株白雌虫数明显低于中国春。连续两年又对17份小麦–卵穗山羊草5M g-5D易位系材料进行抗性鉴定现发,5M g464、5M g466和5M g457抗性较好。     

棉花–小麦条带种植对棉花苗蚜发生及为害的影响

为了探究棉花–小麦条带种植对棉花苗蚜发生及为害的影响,对棉花苗期的蚜虫种群数量及为害情况进行了调查分析。结果表明,棉花–小麦条带种植模式可减轻棉花苗期蚜虫的发生和为害,苗期有翅蚜和无翅蚜数量均显著低于常规种植,分别减少70.4%和84.8%,有蚜株率和卷叶株率分别较常规种植降低67.4%和81.3%;棉花条带中,边行对棉蚜的控制作用显著优于中间行,边行有翅蚜和无翅蚜数量分别比中间行减少了43.7%和54.3%,有蚜株率和卷叶株率分别较中间行降低了52.4%和84.6%。     

小麦族物种线粒体基因rrn18–trnfM区域的序列多样性分析

为了研究线粒体基因组在小麦族物种中的遗传变异与进化关系,选用小麦族的14个二倍体及7个多倍体物种,对其线粒体rrn18-trnfM 基因区域进行PCR扩增并对扩增所得的片段进行克隆测序。获得大小不同的2种片段类型,大片段为513或515 bp,小片段为447或449 bp。其主要差异在trnfM区,即大片段存在trnfM基因,小片段缺失trnfM基因,再次证明以前报道的大麦属和小麦属间的分歧。而中间偃麦草同时存在两扩增片段类型,表明多倍体物种mtDNA具有双亲遗传现象。中间偃麦草的RT-PCR分析发现小片段没有转录,大片段能转录,因而考虑高频重组和选择性表达作为中间偃麦草的线粒体基因组独特的进化系统,这与核基因组进化系统不同。     

Molecular markers to exploit genotype–environment interactions of relevance in organic growing systems

One of the substantial differences between conventional and organic growing systems is the degree to which the farmer can control biotic and abiotic stresses; for organic growing systems varieties are needed with a broad adaptation to annually varying factors, while at the same time a good specific adaptation is necessary with respect to more constant climate and soil conditions. This combination of requirements implies that varieties for organic farming need to be better characterised with respect to genotype × environment interactions than varieties for conventional farming. Such interactions, which often are found for quantitatively expressed traits, are in general difficult to deal with in phenotypic selection. New approaches for QTL analyses (e.g. using physiological models) facilitate estimation of effects of genes on a trait (the phenotype) as a response to environmental influences. From such analyses, markers can be identified which may help to predict the trait expression of a plant genotype in relation to defined environmental factors. The application of markers to select for loci with specific interactions with the environment could, therefore, be especially important for plant breeders targeting organic farming systems.     

小麦–华山新麦草异代换系DH2322的分子细胞遗传学鉴定

利用分子标记、细胞学、基因组原位杂交(GISH)等技术,结合田间农艺性状调查,对小麦–华山新麦草七倍体材料H8911与硬粒小麦D4286杂交F4代分离群体中株系DH2322进行了综合鉴定。华山新麦草基因组特异SCAR标记鉴定表明,DH2322含有华山新麦草遗传物质;细胞遗传学观察显示,DH2322染色体构型为2n=42=21 II;有丝分裂和花粉母细胞减数分裂中期I基因组原位杂交(GISH)鉴定表明,DH2322的染色体由40条小麦染色体和2条华山新麦草Ns染色体构成,且2条Ns染色体能完全配对为一个二价体;SSR和STS分子标记分析表明,DH2322缺失小麦D基因组的2D染色体,而含有华山新麦草的2Ns染色体;农艺性状分析结果表明,DH2322具有双亲的形态学特征,结实性好,穗长和穗粒数显著大于亲本。