小麦田不同杂草群落及防除时间对小麦产量的影响

为明确小麦田不同杂草群落及防除时间对小麦产量的影响,于2013—2015连续两年在山东省聊城市高唐县小麦田中设无草对照区、禾本科杂草区、阔叶杂草区以及混合杂草自然发生区4种不同杂草群落以及不同的杂草防除时间,测定在不同条件下小麦产量及各项产量构成指标的情况。结果表明,阔叶杂草对小麦产量的影响大于禾本科杂草,冬小麦田杂草的最佳防除时间为4月1日之前,在此期间除草对小麦产量影响均不大,但之后防除或不除草会造成小麦严重减产甚至绝产,2014年4月15日除草可造成在阔叶杂草区和杂草混合生长区的小麦减产30.5%和32.6%,不除草可造成在禾本科杂草区、阔叶杂草区和杂草混生区的小麦减产8.6%、91.4%和94.3%,2015年趋势和2014年一致。从构成小麦产量的3个指标来看,杂草危害主要影响小麦的总穗数,其次为穗粒数,对千粒重影响最小。     

猪殃殃与小麦之间竞争的一些研究

1.由于猪殃殃的竞争,小麦穗数、粒数减少,粒重降低,导致减产。田间猪殃殃株数。茎枝数,干物重与小麦产量损失之间有极显著回归关系。猪殃殃茎枝数每增加1万茎/亩,穗数减少0.051万穗,穗粒数减少0.022粒,千粒重降低0.014克。小麦产量损失0.94斤。 2.猪殃殃与小麦共生时间越长,对产量影响越大。与小麦同时出草的猪殃殃,共生到三月底小麦拔节期,减产不显著;共生到四月底小麦抽穗期,减产达极显著水平。初步认为,三月底,四月初是影响小麦产量的临界期。 3.猪殃殃密度大的情况下,除了与小麦竞争,内部竞争也相当激烈,密度越大,分枝的成活率越低。 4.根据其危害损失,结合当前生产水平,建议把防除指标定为60茎/尺~2。猪殃殃是遍布全省、发生和危害正在逐年加重的麦田恶性杂草。1979—1981年,我所曾对其生物学和发生规律、危害损失等作了观察和研究,明确了田间发生密度10株/尺~2以上,即能造成小麦显著减产;3月下旬是药剂防除适期。1983—1984年,着重对猪殃殃和小麦之间的竞争关系及其影响作了一些研究,得出了根据猪殃殃田间发生量来估测小麦产量损失的回归方程式,并根据猪殃殃竞争的临界期,从理论上肯定了3月下旬是春季防除适期;建议改用60茎/尺~2为防除指标,比用株数为指标更准确,更易掌握。     

冬小麦田大穗看麦娘种群动态及对小麦产量的影响

为明确麦田杂草大穗看麦娘Alopecurus myosuroides的田间种群发生动态规律,采用固定样方和随机样方取样方法于2013—2015年在山东省济南市研究了冬小麦田大穗看麦娘田间种群的萌发和生长动态,并分析了不同密度大穗看麦娘对小麦产量及其构成因素的影响。结果表明:在济南市小麦播后20~40 d为大穗看麦娘出苗高峰期,至11月下旬出苗量占全年出苗总量的97.1%。11月上旬,大穗看麦娘开始出现分蘖,至翌年4月上中旬结束,分蘖数平均每株为6.3个,比小麦多3.1个。3月下旬大穗看麦娘开始拔节,4月中旬平均株高超过小麦,5月下旬平均株高达到75.6 cm,高出小麦2.5 cm。5月上旬大穗看麦娘单茎平均鲜重达到最大为1.7 g,小麦为12.6 g。大穗看麦娘出苗、株高、分蘖和鲜重的变化与小麦变化趋势一致,与时间、温度密切相关。随着大穗看麦娘密度的增加,小麦产量急剧下降,当密度达到420株/m~2时,小麦产量损失率高达65.8%。大穗看麦娘对小麦产量构成因素中的穗密度影响最大,其次是穗粒数,对千粒重影响不显著,当密度为420株/m~2时,小麦穗密度减少55.2%,穗粒数减少26.4%。     

麦田雀麦发生动态及其对小麦产量的影响

雀麦(Bromus japonicus)是一种越冬性一年生杂草,是我国北方冬小麦田发生最严重的禾本科杂草之一,对小麦造成严重减产。为明确雀麦在我国冬小麦田的田间发生动态规律,于2013-2015年在山东省泰安市雀麦发生严重的冬小麦田进行相关试验。采用固定样方和随机样方取样的方法,研究冬小麦田雀麦的出苗规律及其在田间的消长动态,同时研究不同密度雀麦对小麦产量的影响。结果表明,小麦播种后7~30 d为雀麦的出苗高峰期,至12月上旬出苗量占总出苗总量的85.3%。11月中旬,雀麦开始分蘖,平均分蘖数为4.8个/株,比小麦多1.3个/株。3月下旬雀麦生长速度加快,4月下旬平均株高超过小麦,5月中下旬平均株高达到115.0 cm,高出同期小麦24.1 cm。5月中旬,雀麦与小麦单株平均鲜重趋于稳定,分别为17.24、37.72 g。雀麦与小麦在株高、鲜重等方面的变化趋势基本一致,与外界温度的变化密切相关。当雀麦密度为5株/m^2时,小麦产量损失率达5.35%,表明少数雀麦即可对小麦产量造成显著减产;随着雀麦密度的增加,小麦产量快速下降,其对小麦产量的影响主要表现在小麦的有效穗密度上,对小麦的千粒质量与穗粒数则影响较小。当雀麦密度为640株/m^2时,小麦产量损失率为36.81%,小麦穗密度减少35.69%。     

野燕麦的危害损失及防除指标研究

野燕麦的危害损失及防除指标研究许浩然，许莉（新疆沙湾县农业技术推广中心８３２１００）野燕麦（ＡｖｅｎａｆａｔｕＬ）是农田中的恶性杂草。沙湾县小麦田发生面积２６６７ｈｍ２，占小麦面积的２０％以上，每年小麦产量直接损失２２５０ｔ。为了揭示野燕麦不同密度对...     

播娘蒿对小麦危害损失的通径分析

应用通径分析原理进行了播娘蒿对小麦每亩有效穗数、每穗粒数、千粒重及产量影响的分析，力图剖析播娘蒿的为害结构与产量损失的形式过程，以及各危害因子（杂草密度、杂草干重、绝对高积重）之间的相互关系。分析结果表明，杂草密度主要影响小麦每亩穗数与千粒重，杂草干重与绝对高积重主要影响每穗粒数与最终产量。播娘蒿的危害引起千粒重下降是造成产量损失的主要因素。     

2013-2016年河南省小麦茎基腐病的发生危害情况及特点

2013-2016年连续4年对河南省不同类型麦田小麦茎基腐病发生和危害情况等进行了调查。结果表明,小麦茎基腐病在河南省已经广泛分布,每年均都有不同程度发生,其中2013年病田率为45.8%,病田白穗率为0.4%~11%;2014年病田率为12.6%,病田白穗率为0.1%~3.7%;2015年病田率为32.5%,病田白穗率为0.1%~16.1%;2016年发生最重,病田率为65.1%,病田白穗率为0.1%~31.5%。调查还发现,河南省小麦茎基腐病发生的特点是北部和西部发生较重;小麦-玉米连作田发生较重,而小麦-水稻连作田块发生较轻;干旱的田块发生危害重。病害产量损失的初步测定结果表明,感病最严重的分蘖病茎高度减少55.8%,且不能结实;能结实病茎较健茎高度减少14.0%~18.0%,穗粒数减少22.7%~54.5%,穗粒重减少33.3%~90.5%,千粒重减少3.2%~73.2%;当病田白穗率为22%时,有效穗数减少33.3%,产量损失达51.6%。本文还针对目前国内对小麦茎基腐病研究薄弱的问题,提出了今后需要加强的研究工作。     

小麦田草大麦的危害及防除指标的初步研究

草大麦每平方米的株数、有效(茎)穗及鲜重与小麦产量构成的三要素(亩穗数、穗粒数、千粒重)和产量之间呈Y=A+BX的直线回归关系;与小麦产量损失率呈Y=AX~B幂回归关系。根据当地小麦生产水平,求出草大麦的防除指标分别为每平方米1.0株、18茎(穗)和鲜重119克。     

咸宁市小麦赤霉病发生规律与防控对策

正小麦赤霉病是影响咸宁市小麦产量和品质的重要因素之一,重发生年份,病穗率一般可达50%左右,高的病穗率可达80%以上,对小麦造成的损失严重。1发生特点1.1重发频率高小麦赤霉病在咸宁市暴发频率高,造成小麦减产,损失大。年度间病情发生有差异,大约每两年就重度或中度发生一次,2012年、2014年和2016年     

泽漆对小麦的为害损失及经济阈值研究

为明确泽漆的发生对小麦产量及其构成因素的影响,人工接种结合田间自然出草进行泽漆不同密度对小麦为害损失试验。１９９５－１９９６年研究结果表明,泽漆发生密度和小麦产量及穗数损失率的最佳数学模型均直线函数关系,方程分别为：Ｙ＝－０．３９１８＋１．５１９Ｘ,Ｙ１＝２．２３２＋１．５５３Ｘ。泽漆的发生为害对小麦穗粒数、千粒重的影响不显著。经济阈值计算结果表明,用使它隆进行防除,泽漆发生密度达３．０株／ｍ＾３     

Influence of humidity on incidence of Didymella bryoniae on cucumber leaves and growing tips under controlled environmental conditions

The influence of relative humidity, leaf wetting, mechanical injury and inoculum concentration on the incidence ofDidymella bryoniae on growing tips and young and older leaves of cucumber was studied in growth chambers.Infection was rare at 60% r.h. It increased at 95% r.h. and was most serious if the leaves were kept wet. A period of 1 hour of free water was sufficient for the initial stage of infection. For further expansion of the disease, leaf wetness was required.A high relative humidity did not predispose leaves to infection byD. bryoniae. Wounding was essential for infection of older leaves, but not for infection of young plant tissue.A higher conidial concentration increased infection. Without keeping, the leaves wet at 95% r.h. a tenfold conidial concentration was needed to get equal infection as with leaf wetting.To control the disease by means of the climate, it is of major importance to prevent the presence of free water on plant parts.Samenvatting De invloed van de relatieve luchtvochtigheid, het bevochtigen van het blad, mechanische beschadiging en inoculumconcentratie op het optreden vanDidymella bryoniae op groeipunten en jonge en oudere bladeren van komkommer is in klimaatkasten onderzocht.Aantasting kwam zelden voor bij 60% R.V., nam toe bij 95% R.V. en was het ernstigst als de bladeren nat werden gehouden. Voor de eerste fase van infective was de aanwezigheid van vrij water gedurende 1 à 2 uur voldoende. Voor een verdere uitbreiding van de aantasting moest het blad nat zijn.Een hoge relatieve luchtvochtigheid had geen predispositie-effect of de infectie van bladeren doorD. bryoniae.Voor de infectie van oudere bladeren was verwonding nodig, voor die van jong planteweefsel niet.Een hogere concentratie van conidiën verhoogde de aantasting. Zonder het blad nat te houden, was een tienvoudige concentratie van conidiën nodig om een gelijke infectie te verkrijgen als met bladbevochtiging.Voor de bestrijding van de ziekte via het klimaat is het tegengaan van de aanwezigheid van vrij water op plantedelen van het grootste belang.Seconded to the Glasshouse Crops Research and Experiment Station, Zuidweg 38, 2671 MN Naaldwijk, the Netherlands.     

Investigations on the effect of haulm destruction and additional root cutting on black scurf on potato tubers

In greenhouse experiments factors which are involved in the stimulation of sclerotia formation byRhizoctonia solani Kühn on potato tubers after haulm destruction were investigated. Cutting off the shoot stimulated the production of sclerotia as much as chemical haulm destruction. This was also observed when potato tubers were grown away from the roots in a separate compartment filled with steamed perlite. Fewer sclerotia were produced when roots were cut in addition to haulm destruction compared to haulm destruction alone. Cutting off the roots alone often stimulated sclerotia production. The data indicate that sclerotia production was directly affected by the tuber and probably due to physiological changes in the tuber caused by elimination of the shoot.Samenvatting In kasproeven werd onderzocht welke factoren betrokken zijn bij de stimulering van de produktie van sclerotiën op aardappel doorRhizoctonia solani Kühn als gevolg van loofvernietiging. Afknippen van het loof stimuleerde de vorming van sclerotiën evenzeer als chemische vernietiging. Na afknippen van het loof trad de stimulering ook op bij knollen, die zich ruimtelijk gescheiden van de wortels in gestoomd vochtig perliet konden ontwikkelen. Doodspuiten plus doorsnijden van de wortels resulteerde in minder lakschurft dan doodspuiten alleen. Wanneer alleen de wortels werden doorgesneden resulteerde dat vaak in meer lakschurft. De vorming van sclerotiën wordt dus direct door de knol beïnvloed. Dit effect lijkt voort te komen uit fysiologische veranderingen in de knol.     

Effects of neemgard on phytophagous and predacious mites and on Spiders

The effects of Neemgard, an acaricidal and fungicidal formulation obtained from neem (Azadirachta indica) seed kernels, on the phytophagous miteTetranychus cinnabarinus, the predacious mitePhytoseiulus persimilis, and the predatory spiderChiracanthium mildei, were investigated in laboratory experiments. Neemgard was highly toxic toT. cinnabarinus but had no toxic effect onC. mildei orP. persimilis. Another neem formulation—the insecticidal Neemix 45—caused conspicuous repellency, but no mortality, inT. cinnabarinus.     

Use of carbendazim and carbendazim-resistant yeasts to create different yeast densities on wheat leaves for field studies on biological control

Phyllosphere yeasts may play an important role in suppressing necrotrophic pathogens. In a randomized block design, yeast densities on flag leaves and second leaves of field-grown wheat were left unchanged (D), or were lowered by sprayings with carbendazim (A), or were raised by sprayings with a mixture ofSporobolomyces roseus, Cryptococcus laurentii var.flavescens and nutrients (B), or with carbendazim, carbendazim-resistantS. roseus andC. laurentii var.flavescens and nutrients (C). The application of carbendazim to plots A and C would avoid a biased interference of carbendazim due to other effects than reducing the natural yeast population. Prolonged differences in yeast density would be reflected in differences in severity of diseases caused by carbendazim-insensitive necrotrophic pathogens.Both treatments B and C enhanced the yeast density about 10-fold at the beginning of leaf colonization, 2 to 3 weeks after leaf emergence. Untreated leaves (D), however, were rapidly leaves. Initially, the yeasts were suppressed by carbendazim (A). However, progressively the yeast population consisted of carbendazim-resistant strains which made the carbendazim sprayings ineffective. Therefore, the substantial differences in yeast density were of limited duration. The effect of the treatments on naturally occurringMycosphaerella graminicola (anam.Septoria tritici), Puccinia recondita f. sp.tritici and the total necrotic leaf area (D-value) is discussed.Samenvatting Fyllosfeergisten kunnen misschien een belangrijke rol spelen in de onderdrukking van necrotrofe pathogenen. In een blokkenproef werd de dichtheid van gisten op vlagbladeren en tweede bladeren niet beïvvloed (D) of verlaagd door bespuitingen met carbendazim (A), of verhoogd door bespuitingen met een mengsel van gisten (Sporobolomyces roseus enCryptococcus laurentii var.flavescens en voedingsstoffen (B), of met een mengsel van carbendazim, carbendazim-resistenteS. roseus enC. laurentii var.flavescens en voedingsstoffen (C). De grootste verschillen in dichtheden van de gistpopulaties werden verwacht tussen de behandelingen A en B of C. Door alle veldjes A en C met carbendazim te behandelen wordt een eenzijdig effect van carbendazim, berustend op andere eigenschappen dan de onderdrukking van de natuurlijke gistpopulatie, voorkomen. Langdurige verschillen in de populatiedichtheden van de gisten zouden weerspiegeld kunnen worden in verschillen in aantasting door carbendazimongevoelige necrotrofe pathogenen.Aan het begin van de bladkolonisatie door gisten, 2 tot 3 weken na het verschijnen van het blad, leidde zowel behandeling B als C tot, een 10-voudige verhoging van de gistdichtheid. De onbehandelde bladeren (D) werden echter spoedig door de van nature voorkomende gisten gekoloniseerd en het verschil tussen de onbehandelde en met gist bespoten bladeren werd snel kleiner. Aanvankelijk werden de gisten door carbendazim (A) onderdrukt. Geleidelijk bestond de gistpopulatie echter uit carbendazim-resistente stammen, zodat de carbendazim bespuitingen nauwelijks meer effect hadden. Hierdoor werden grote verschillen in gistdichtheden niet langdurig gerealiseerd. Het effect van de behandelingen op de natuurlijke infectie doorMycosphaerella graminicola (anam.Septoria tritici), Puccina recondita f. sp.tritici en op het totale dode bladoppervlak (D-waarde) wordt besproken.     

Multiple Selection of Potato Cyst Nematode Globodera pallida Virulence on a Range of Potato Species. I. Serial Selection on Solanum-hybrids

A series of selection experiments on potato cyst nematode Globodera pallida, pathotype Pa1, tested the virulence response of the nematode to a range of resistant potato Solanum genotypes. Alleles conferring virulence against all four Solanum sources used in the study (i.e. Solanum vernei, S. multidissectum, S. sanctae-rosae and S. tuberosum ssp. andigena) were detected. Selection for multiple virulence against a combination of resistant sources resulted in the originally-selected virulence genes being retained or lost. The mechanism, or basis, of potato cyst nematode resistance differs between the Solanum species. The appropriate use of resistance cultivars produced from a range of Solanum-resistant species offers a management tool for controlling potato cyst nematode levels in infested land.     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Effects of temperature increase on the epidemiology of three major vector-borne viruses

The epidemiologies of Maize streak virus (MSV), Maize stripe virus (MSpV), and Maize mosaic virus (MMV) were compared in La Réunion over a three year-period. Disease incidence caused by each virus was assessed, and the leaf and planthopper vector populations (Cicadulina mbila and Peregrinus maidis) were estimated in weekly sowings of the temperate, virus-susceptible maize hybrid INRA 508 and of the composite resistant cv. IRAT 297. MSV caused the most prevalent disease and MMV the least, with lower incidences in cv. IRAT 297 than in INRA 508. For each plant–virus–vector combination, (a) disease incidence was positively correlated to vector abundance, often with 1 month of time lag; (b) annual periodicity of disease incidence and of vector numbers was consistent with highest autocorrelations and a time lag of 12 months, (c) vector numbers and disease incidence were closely associated with temperature fluctuations, both remaining relatively constant below 24°C and increasing rapidly above this threshold temperature. By contrast, relationships with rainfall and relative humidity (RH) were less consistent. Overall, 63 to 80% of the variance of disease incidence was explained through stepwise regression with vector number, temperature, and sometimes also rainfall or RH. The simple epidemiological model proposed underlines the close link between increased temperature and possible (re-) emergence of these three diseases in a maize cropping area.     

基于Suomi NPP/VIIRS数据的青海省东部农业区夏季土壤水分监测模型的应用研究

土壤水分是量度干旱程度最重要的指标，如何对其有效监测与预警一直是各界致力解决的重大科学问题。基于Suomi NPP/VIIRS数据的温度植被干旱指数TVDI、归一化植被水分指数NDWI、植被状况指数VCI,分别构建了青海省东部农业区3种土壤水分监测模型，利用连续的野外定点观测数据及生态站点观测数据进行模型检验，并在2017年夏旱过程进行了应用检验。结果表明：2012—2016年模型回代检验中，TVDI指数模型表现最优(RMSE为4.4%),其次为VCI指数模型(RMSE为4.7%),NDWI指数模型表现最差(RMSE为5.2%);2018—2020年夏季互助遥感检验场定点观测检验中，TVDI指数模型表现最好(RMSE为3.8%),VCI指数模型次之(RMSE为5.0%),NDWI指数模型表现最差(RMSE为8.8%);2017年夏季干旱过程中，TVDI指数模型反演的旱情发展过程及分布范围与实际旱情情况相符，而NDWI指数模型反演的旱情分布范围明显偏小，VCI指数模型甚至不能反映旱情缓解、解除期的变化。     

Effect of GRAS compounds on mycelial growth, pectic enzyme activity and disease severity of postharvest pathogens on rambutan (Nephelium lappaceum)

The GRAS compounds cinnamaldehyde (at 30 ppm), acetaldehyde (at 70 ppm), benzalde-hyde (at 50 ppm) and potassium metabisulphite (at 250 ppm) either completely inhibited or significantly reduced thein vitro mycelial growth ofGliocephalotrichum microchlamydosponim,Colletotrichum gloeosporioides andBotryodiplodia theobromae, the causative fungi of brown spot, anthracnose and stem end rot, respectively, of rambutan fruits,Nephelium lappaceum. The four compounds also significantly reduced the severity of all three diseases and the activity of pectic lyase and polygalacturonase enzymes secreted by the three fungi.     

Ecological data on predators ofParlatoria pergandii on sour orange trees in southern Greece

The present study was carried out in southern Greece during 1993-1995 on sour orange trees infested with the diaspididParlatoria pergandii Comstock. The activity of the natural enemies of the scale, the composition of their population during the year as well as their relation with hymenopterous parasitoids of coccinellids, were studied.P. pergandii was parasitized by a hymenopterous endoparasite of the genusEncarsia and the extent of parasitization ranged between 5.2% and 14.1%. The observed predators were the coccinelidsChilocoms bipustulatus Linnaeus andRhyzobius lophanthae Blaisdell and the nitidulidCybocephalus fodori Endrödy-Younga. The predominant predator wasR. lophanthae (84.3% of the larvae and 73.3% of the adults), which was active throughout the whole year in all of its developmental stages. Second most abundant was the predatorC. bipustulatus (15.7% of the larvae and 20% of the adults) and third the predator C.fodori (6.7% of the adults). Larvae ofC. bipustulatus were observed to be parasitized by the hymenopterous parasitoidsHomalotylus flaminius Dalman (Encyrtidae) andTetrastichus coccinellae Kurdjumov (Eulophidae). The parasitization percentage increased gradually from 4% in mid June to 94% around the end of September. Laboratory tests confirmed that the above mentioned parasitoids cannot infest larvae or nymphs ofR. lophanthae.