日本看麦娘对高效氟吡甲禾灵代谢抗性的初步研究

为了明确日本看麦娘对高效氟吡甲禾灵(haloxyfop-R-methyl)的代谢抗性机理,研究了抗性和敏感生物型体内细胞色素P450还原酶(cytochrome P-450 monooxygenases,P450)和谷胱甘肽-S-转移酶(glutathione-S-transferases,GSTs)的活性差异。结果表明,未用药剂处理时,抗性日本看麦娘P450与GSTs的活性均高于敏感日本看麦娘。高效氟吡甲禾灵茎叶喷雾处理2 d后,敏感植株反应剧烈,P450与GSTs活性均呈现急剧的变化趋势,而抗性种群的变化趋势平缓。处理后第6 d,敏感种群较抗性种群先出现下降趋势,其活性也明显低于抗性种群。处理后第10 d活性均降到最低,并且依然低于施药初期。从而可以得出:高效氟吡甲禾灵被抗性日本看麦娘体内的细胞色素P450还原酶催化,经过羟化作用迅速解毒,并在GSTs的催化下形成了无毒或低毒的化合物,使其免受伤害。表明代谢酶活性增强是日本看麦娘对高效氟吡甲禾灵产生抗性的机理之一。     

安徽省部分地区冬小麦田日本看麦娘Alopecurus japonicus对精噁唑禾草灵的抗性发生现状及ACCase基因突变研究

日本看麦娘Alopecurus japonicus是中国冬小麦田和油菜田主要恶性禾本科杂草之一。为了明确安徽省部分地区日本看麦娘对精齅唑禾草灵抗性发生情况及可能存在的抗性机制,本研究在安徽省天长市日本看麦娘发生严重区域冬小麦田共采集10个种群,采用温室盆栽法在整株水平上测定了不同种群对精齅唑禾草灵的抗性水平,扩增并比对了抗性和敏感种群之间靶标酶乙酰辅酶A羧化酶 (Acetyl-CoA carboxylase,ACCase) 基因部分序列的差异。结果显示,与敏感种群相比,10个抗性种群对精齅唑禾草灵均产生了高水平抗性,抗性指数在30.50~58.55之间。不同抗性种群均发生了ACCase基因突变,其中8个种群发生了第1 781位异亮氨酸 (Ile) 到亮氨酸 (Leu) 突变,2个种群发生了第2 027位色氨酸 (Trp) 到半胱氨酸 (Cys) 突变。此外,各种群均具有较高的ACCase基因突变频率 (≥80%)。研究表明,抗性日本看麦娘在安徽省部分地区发生较为严重,ACCase基因突变是导致不同日本看麦娘种群对精齅唑禾草灵产生抗性的重要原因之一。相对于第2 027位,日本看麦娘ACCase基因更倾向于在第1 781位产生突变以表现靶标抗性。     

安徽省部分地区冬小麦田日本看麦娘Alopecurus japonicus对精鰁唑禾草灵的抗性发生现状及ACCase基因突变研究

日本看麦娘Alopecurus japonicus是中国冬小麦田和油菜田主要恶性禾本科杂草之一。为了明确安徽省部分地区日本看麦娘对精齅唑禾草灵抗性发生情况及可能存在的抗性机制,本研究在安徽省天长市日本看麦娘发生严重区域冬小麦田共采集10个种群,采用温室盆栽法在整株水平上测定了不同种群对精齅唑禾草灵的抗性水平,扩增并比对了抗性和敏感种群之间靶标酶乙酰辅酶A羧化酶(Acetyl-CoA carboxylase,ACCase)基因部分序列的差异。结果显示,与敏感种群相比, 1 0个抗性种群对精齅唑禾草灵均产生了高水平抗性,抗性指数在30.50～58.55之间。不同抗性种群均发生了ACCase基因突变,其中8个种群发生了第1 781位异亮氨酸(Ile)到亮氨酸(Leu)突变,2个种群发生了第2 027位色氨酸(Trp)到半胱氨酸(Cys)突变。此外,各种群均具有较高的ACCase基因突变频率(≥80%)。研究表明,抗性日本看麦娘在安徽省部分地区发生较为严重,ACCase基因突变是导致不同日本看麦娘种群对精齅唑禾草灵产生抗性的重要原因之一。相对于第2 027位,日本看麦娘ACCase基因更倾向于在第1 781位产生突变以表现靶标抗性。     

抗精噁唑禾草灵的日本看麦娘ACCase基因突变

为明确日本看麦娘抗性种群对精噁唑禾草灵的抗性水平及抗性产生的分子机制,采用整株水平测定法测定了日本看麦娘对精噁唑禾草灵的抗性水平,扩增和比对了日本看麦娘抗性和敏感种群间乙酰辅酶A羧化酶(acetyl-Co A carboxylase,ACCase)基因的差异。结果显示,与敏感种群AH-7相比,抗性种群AH-25对精噁唑禾草灵的抗性倍数为33.82;AH-25种群ACCase基因CT区域2 078位氨基酸发生了突变,由天冬氨酸GAT突变为甘氨酸GGT;AH-25种群对炔草酯、烯草酮和烯禾啶产生了高水平的抗性,抗性倍数分别为35.66、38.64和29.14,对高效氟吡甲禾灵产生了低水平的抗性,抗性倍数为3.04,对精喹禾灵和唑啉草酯较敏感。表明ACCase基因2 078位氨基酸的突变可能是导致精噁唑禾草灵产生高水平抗性的重要原因。     

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%。     

抗精噁唑禾草灵和甲基二磺隆看麦娘ACCase和ALS基因突变

为明确看麦娘Alopecurus aequalis抗性种群YL的靶标抗性机制,采用基因克隆法对看麦娘抗性和敏感种群间乙酰辅酶A羧化酶(ACCase)和乙酰乳酸合成酶(ALS)基因序列进行扩增、克隆和测序,比对二者ACCase和ALS基因序列的差异,探寻其产生抗药性突变的基因位点,同时测定该突变型抗性种群YL对不同ACCase和ALS抑制剂类除草剂的交互抗性。结果显示,与看麦娘敏感种群TL相比,抗性种群YL的ACCase基因CT区域第2 041位氨基酸由异亮氨酸(ATT)突变为天冬酰胺酸(AAT),ALS基因Domain A区域第197位氨基酸由脯氨酸(CCC)突变为精氨酸(CGC)。看麦娘抗性种群YL对ACCase抑制剂炔草酯产生了高水平抗性,抗性倍数为43.96,对高效氟吡甲禾灵和精喹禾灵产生了中等水平抗性,抗性倍数分别为18.33和15.87,对唑啉草酯、烯草酮和烯禾啶较敏感;对ALS抑制剂氟唑磺隆产生了低水平抗性,抗性倍数为8.39,对啶磺草胺和咪唑乙烟酸较敏感。表明ACCase基因第2 041位和ALS基因第197位氨基酸突变是导致看麦娘抗性种群YL对精噁唑禾草灵和甲基二磺隆同时产生抗性的重要原因之一。     

油菜田看麦娘对精喹禾灵的抗性水平及抗性机理研究

采用培养皿种子萌发法和盆栽法测定了湖南省境内长沙市、永州市、常德市、益阳市、浏阳市、岳阳市、娄底市7个市州10个地区油菜田看麦娘潜在抗药性种群对精喹禾灵的抗性水平, 测定了常德市桃源地区看麦娘潜在抗药性种群以及敏感种群谷胱甘肽-S-转移酶(GSTs)对精喹禾灵的敏感性, 对桃源地区看麦娘抗性品系及敏感品系ACCase基因片段进行扩增和测序, 比较了两种生物型的基因序列。培养皿种子萌发法测定结果表明：常德市桃源地区看麦娘抗药性生物型对精喹禾灵的抗性水平最高, 抗性倍数为10.50倍, 其他地区看麦娘抗性倍数在2.01~7.09 倍之间, 抗性水平不明显; 盆栽法测定结果表明：桃源地区看麦娘抗性倍数最高, 为25.30倍, 其他地区看麦娘抗性倍数在2.43~9.47倍之间, 尚未产生明显抗药性。经精喹禾灵处理后, 看麦娘抗药性生物型的GSTs活力在第5天明显高于敏感生物型, 表明GSTs的活性是引起看麦娘对精喹禾灵抗性的重要因子。通过靶标基因片段扩增与DNA测序比对发现, 抗药性生物型氨基酸序列第93位比敏感生物型多出一个丙氨酸, 抗药性的产生与靶标基因的突变是否相关需要进行进一步验证。     

日本看麦娘对氯磺隆的抗药性研究

在连续施用氯磺隆不同年限的麦田采集日本看麦娘种子，室内通过不同剂量的氯磺隆处理，测定对日本看麦娘幼苗的苗高抑制率、根长抑制率、植株鲜重抑制率。试验结果表明：连续施用氯磺隆5-6年、异丙氯混配剂5年以上，日本看麦娘的抗性指数达l111．3～l528．3倍；连续施用氯甲磺隆混配剂3年、异丙氯混配剂2—3年，日本看麦娘的抗性指数为65．5倍；对日本看麦娘敏感种群(S)和不同抗性水平的抗性种群(R)幼苗的苗高、根长、植株鲜重的相对毒力倍数存在一定的差异。     

小麦田精噁唑禾草灵抗性杂草的田间监测与防控

田间监测试验表明,69g/L精噁唑禾草灵EW在小麦田疑似抗性杂草种群试验区对看麦娘、野燕麦、菵草等一年生禾本科杂草防效较差,综合株防效只有58.21%,综合鲜重防效也只有67.67%;69g/L精噁唑禾草灵EW在小麦田敏感杂草种群试验区对看麦娘、野燕麦、菵草等一年生禾本科杂草防效较好,综合株防效87.61%,综合鲜重防效88.48%。表明多年使用精噁唑禾草灵的小麦田看麦娘、野燕麦、菵草等种群均已对精噁唑禾草灵产生了抗药性。     

看麦娘对甲基二磺隆靶标抗性的快速检测

甲基二磺隆是防除小麦田看麦娘Alopecurus aequalis等禾本科杂草的主要除草剂品种之一,但目前中国山东、江苏及安徽等地已有部分看麦娘种群对其产生了抗性。ALS基因197位点突变是看麦娘对甲基二磺隆产生抗性的重要机理,根据突变型和野生型看麦娘在197位点处碱基序列的不同,本研究设计出了一种衍生性酶切扩增多态性序列(dCAPS)分子标记方法,可用于197位点突变的快速检测。通过在引物D197F序列的3′ 端引入一个错配碱基,扩增所得不同种群看麦娘的ALS片段经限制性内切酶BamH I酶切后表现出多态性:野生敏感型分别产生了200和36 bp的2个条带;纯合突变型因无法被切开,只有236 bp的一个条带;而杂合突变型则同时产生了上述3个条带。该dCAPS检测结果准确、可靠,与经典的整株水平测定结果一致,并且可同时检测197位点上任一形式的突变。研究结果可为看麦娘等禾本科杂草对甲基二磺隆靶标抗性的快速检测提供理论依据。     

灌丛密度对毛乌素沙地南缘沙柳生长及土壤水分动态的影响

在毛乌素沙地南缘选择不同栽植密度(0.2、0.6株/m2和0.8株/m2)的沙柳人工灌丛,对沙柳生长特征及土壤水分进行研究。结果表明:不同栽植密度沙柳的生长特征存在显著差异,沙柳株高、平均冠幅直径、地上生物量、叶片生物量和茎生物量随着栽植密度的增加呈先增加后降低趋势。不同栽植密度沙柳灌丛土壤水分动态存在明显差异,沙柳灌丛土壤含水量随着栽植密度增大呈先增加后降低趋势,在栽植密度0.6株/m2(T2)达到最大值。在毛乌素沙地生境条件下,与水资源容量相适应的沙柳栽植密度约为0.6株/m2,在该栽植密度下土壤水分含量基本上能满足沙柳的生理生态需水。     

内蒙古燕麦叶斑病的发生及其影响因素

为探究内蒙古田间影响燕麦叶斑病的因素，采用正交试验设计对燕麦品种、播期、种植密度、施氮量、施磷量和灌水量6个因素及其组合于2009—2011年进行连续3年的重复试验，运用逐步回归法对3年试验数据进行分析，探讨不同因素及其组合对燕麦叶斑病的影响。正交方差和分析表明，播期和品种是影响燕麦叶斑病的主要因素，方差贡献率分别为78.69%和12.20%；而施氮量、施磷量和灌水量对燕麦叶斑病发生程度均无显著影响。拟合分析获得燕麦叶斑病发生程度与播期(x₂)、品种(x₁)和种植密度(x₃)之间的非线性回归方程为y=51.99-6.45x2-0.39x₁x₃，表明适当推迟播期、选择抗性较高的燕麦品种且相对密植可减轻燕麦叶斑病的发生程度。     

杂草稻对水稻生长及产量的影响

通过室内试验和田间试验明确了杂草稻对水稻生长、产量构成因子和产量的影响。水稻营养生长期,不同杂草稻密度对水稻基本苗、株高、单株鲜重、分蘖、倒二叶长与宽均没有影响。而水稻株高、有效穗数、穗长、一次枝梗数、穗粒数、千粒重、结实率、实际产量等均随杂草稻密度的增加而呈现下降趋势。杂草稻密度为1株/m2可导致水稻产量损失9.15%,当杂草稻密度达7株/m2时可导致水稻产量损失50%以上,杂草稻密度达到12株/m2时水稻产量损失可高达72.29%。     

Mature plant resistance of potato against some virus diseases. I. Concurrence of development of mature plant resistance against potato virus X,and decrease of ribosome and RNA content

Four of five weeks after planting a group of potato plants ‘Bintje’ was inoculated with potato virus X (PVX). Other groups were inoculated at intervals of 14 days. Tubers produced by plants inoculated 35 days after planting were all infected. The plants inoculated 49 days or later after planting produced few infected tubers. The latter had developed mature plant resistance against PVX infection. The ribosome and RNA contents of leaves were measured by application of adsorption chromatography. A rapid decrease in ribosome and RNA contents occurred in plants at the time of rapid increase in the rate of mature plant resistance. The decrease was most distinct in the fifteenth leaf and therefore the contents in this leaf seem to give a good indication of the rapid increase in resistance.     

不同种植方式对棉田土壤温度、棉花耗水 和生长的影响

通过2010-2011年大田试验,研究了平作、沟播和地膜覆盖(沟播+地膜覆盖)下棉花生长、水分消耗以及棉田地温变化情况.结果表明:地膜覆盖对棉花苗期和现蕾期地温日变化、最高温影响最大,通过提高土壤温度的最高值来影响土壤温度变化,开花结铃期以后种植方式对地温的影响不明显;不同种植方式对土壤水分也产生了一定影响,覆膜处理的土壤含水量高于其他2种处理,2010年覆膜和沟播处理比平作处理下的水分利用效率分别提高62.4％和25.3％,2011年为26.1％和10.3％;覆膜处理下的棉花净光合速率、生物量和籽棉产量都高于平作和沟播处理,而沟播与平作间的差异不明显;与平作相比,2010和2011年覆膜和沟播处理下的棉花水分利用效率分别提高了0.17、0.10 kg·m-3和0.10、0.03 kg·m-3.覆膜处理与沟播和平作处理相比,能够提高棉花生育前期的地温,有效地保持土壤水分,有利于棉花增产,最终提高了水分利用效率.     

Planting density affected biomass and grain yield of maize for seed production in an arid region of Northwest China

Field experiments were conducted from 2012 to 2015 in an arid region of Northwest China to investigate the effects of planting density on plant growth, yield, and water use efficiency(WUE) of maize for seed production. Five planting densities of 6.75, 8.25, 9.75, 11.25 and 12.75 plants/m~2 were conducted in 2012, and a planting density of 14.25 plants/m~2 was added from 2013 to 2015. Through comparison with the Aqua Crop yield model, a modified model was developed to estimate the biomass accumulation and yield under different planting densities using adjustment coefficient for normalized biomass water productivity and harvest index. It was found that the modified yield model had a better performance and could generate results with higher determination coefficient and lower error. The results indicated that higher planting density increased the leaf area index and biomass accumulation, but decreased the biomass accumulation per plant. The total yield increased rapidly as planting density increased to 11.25 plants/m~2, but only a slight increase was observed when the density was greater than 11.25 plants/m~2. The WUE also reached the maximum when planting density was 11.25 plants/m~2, which was the recommended planting density of maize for seed production in Northwest China.     

基于Richards模型的全膜双垄沟播与传统栽培模式玉米生长势差异研究

应用Richards生长方程,以春玉米为材料,设了3种栽培处理,从动态数学模型的角度,研究大田条件下全膜双垄沟播模式与传统栽培模式玉米的生长势特征差异及对产量的影响。结果表明:3种处理株高、单株叶面积、单株可见叶数生长积累量均呈"慢—快—慢"的S型Richards模型曲线变化;全膜双垄沟播玉米各指标的生长累积Richards曲线和生长速率及速率变化率曲线形态与半膜和露地对照相比有明显差异,其生长起始势(R0)高,生长势指标进入指数和稳定生长阶段早于对照8~20 d;最大生长速率及出现的时间都明显高于和早于露地对照,全膜双垄沟播玉米的株高最大增长速率为6.755 cm·d~(-1),是对照的1.384倍;单株绿叶面积最大增长速率为330.6 cm2·d~(-1)·株~(-1),是对照的1.391倍;单株可见叶数最大增长速率为0.412片·d~(-1)·株~(-1),是对照的1.383倍;全膜双垄沟播玉米增长速率变化幅度大,呈现加速快但减速也快的特点;稳定增长阶段明显增长,为露地对照的1.493~1.618倍。全膜双垄沟播使作物在生长后期将更多的能量分配给了生殖生长,使玉米叶片后期早衰速度减慢,利于玉米抽雄授粉和灌浆,表现较高的穗粒数、粒叶比和百粒重,显著提高产量。     

Development of Oculimacula yallundae and O. acuformis (eyespot) on leaf sheaths of winter wheat in the UK in relation to thermal time

In a controlled environment (15/10°C) (day/night) container experiment on winter wheat (cv. Avalon), eyespot incidence (percentage of plants affected) and number of leaf sheaths penetrated after 6 weeks increased with inoculum concentration (10²−10⁶ conidia mL⁻¹) of Oculimacula yallundae (OY) or Oculimacula acuformis (OA), but there was no difference between the two species. In an outdoor container experiment, seedlings inoculated with OY 2 weeks after sowing had a greater incidence of eyespot than those inoculated with OA, when assessed 7 weeks after inoculation. Seedlings inoculated with OA at 10 or 20 weeks after sowing developed more severe eyespot by maturity than those inoculated with OY. In an experiment at 15/10°C with seedlings inoculated with OY + OA 2 weeks after sowing, more leaf sheaths were penetrated by OY (3·0 per plant) than OA (2·3 per plant) 6 weeks after inoculation. Field experiments with winter wheat consistently showed leaf sheath production, leaf sheath death, and number of leaf sheaths infected or penetrated by OA or OY were related linearly to thermal time (°C days) after sowing. Depending on cultivar, season and sample, a new leaf sheath was produced in 116–216°C days; a leaf sheath died in 221–350°C days; and infection of a new leaf sheath occurred in 129–389°C days. The mean number of living leaf sheaths infected differed between samples, cultivars and seasons for both OY and OA. Regression analysis of the 1985/86 data suggested that OY progressed more rapidly than OA through the leaf sheaths, and that both the pathogens progressed more rapidly than the rate of leaf sheath death, but more slowly than the rate at which leaf sheaths were produced. It also suggested that OA progressed more slowly than the rate at which leaf sheaths died in 1987/88, but OY did not.     

Effects of the sowing depth and temperature on the seedling emergence and early growth of wild barley (Hordeum spontaneum) and wheat

The experiment was conducted under a controlled environment to study the effects of different temperature regimes (15/10°C, 20/15°C, and 25/20°C day/night) and sowing depths (0, 2, 4, and 6 cm) on the seedling emergence and early growth (height gain) of wheat (cv. Marvdasht) and wild barley ( Hordeum spontaneum ). The cumulative emergence and plant height gain over time were modeled with the use of a logistic function. For a particular temperature regime, the maximum percentage emergence (E _max ) of wheat was higher than that of wild barley across all sowing depths. The maximum and minimum E _max values for both species occurred at 20/15°C and 25/20°C, respectively. The time taken to reach 50% of the E _max (i.e. E₅₀) increased with the sowing depth in both species under all temperature regimes. The E₅₀ of wild barley was greater than that of wheat for all temperature regimes, with maximum differences observed at 20/15°C. The greatest maximum plant height (H _max ) was observed at the surface planting for both plants. The H _max was reduced at temperatures either lower or higher than 20/15°C, with a more notable reduction in wild barley. At all temperature regimes, the time taken to reach 50% of the H _max (i.e. H₅₀) increased linearly with the sowing depth but, at higher temperatures, the accelerated growth rate reduced the H₅₀. The wild barley seedling emergence and height gain rate, as expressed relative to those of wheat, revealed the highest superiority of wheat over wild barley at 25/20°C and the sowing depth of 4 cm.     

不同间作种植模式对棉花生长发育及品质影响

本研究旨在通过大田试验,分析塔里木地区不同枣棉间作间距对花铃期棉花生长发育以及品质的影响,为优化枣棉间作种植模式提供理论依据。结果表明:1棉花与红枣行间距主要影响棉花盛铃-吐絮进程。M1模式(距离红枣1.5 m处种植棉花)棉花生育期最短,为143 d;M3模式(距离红枣0.5 m处种植棉花)最长,为149d。2花铃期,M2模式(距离红枣1.0 m处种植棉花)株高、茎粗、成铃数均优于其他模式。3M1模式棉花叶片、茎秆干物质积累显著高于其他模式。4M1模式棉花产量为2 436.79 kg·hm-2,显著低于其他处理,但是衣分率(0.447)、霜前花率(83.24%)显著高于其他处理;M2模式籽棉产量为4 071.87 kg·hm-2,显著高于其他处理。5随棉花与红枣行间距的减小(M1→M3),棉纤维反射率小幅上升,断裂比强度、马克隆值呈降低趋势。结合生产实际,阿拉尔垦区幼龄枣园中棉花与红枣保持1.0 m距离,能够产生较高的经济效益。