外来植物阔叶丰花草的研究进展

阔叶丰花草(Borreria latifolia)属于茜草科一年生草本植物,原产热带美洲,20世纪30年代引入我国华南,现今已经逃逸为野生。目前人们对阔叶丰花草生物学特征和生长习性的认识不足,不利于其防治和应用价值的开发。本文从地理分布、生物学和生态学特性、危害及防治、利用4个方面总结了阔叶丰花草的最新研究成果,提出了未来展望,以期为今后阔叶丰花草的治理及进一步开发其在农业领域中的应用提供参考依据。

珠三角部分地区菜茬免耕旱直播稻田杂草调查

为明确菜茬免耕旱直播稻田中杂草种类及群落结构,采用倒置“W”形取样法在珠三角部分地区的田块进行杂草调查。调查结果表明,珠三角部分地区菜茬免耕旱直播稻田共有杂草29种,隶属于15科23属,其中优势种杂草4种,区域优势种杂草5种,常见杂草7种,一般杂草13种。牛筋草、光头稗、稗、碎米莎草等在不同地区菜茬免耕旱直播稻田总体相对优势度较高。博罗县菜茬免耕旱直播稻田杂草群落的物种丰富度、Shannon-Wiener多样性指数和Pielou均匀度指数均明显低于花都区和白云区,但其Simpson优势度指数较高。

植保无人机喷施草铵膦在叶菜田清园灭茬中的效果

为明确植保无人机喷施草铵膦在叶菜田清园灭茬中的应用前景,以200 g/L草铵膦水剂作为试验药剂,对P20 2018款植保无人机雾滴沉积分布与飘移情况进行研究,并比较不同施药方式及喷液量处理对叶菜残茬及主要杂草的防除效果。结果表明,当P20 2018款植保无人机飞行速度为3 m/s、高度为1. 5 m(距植物冠层)、喷液量为15. 0～22. 5 L/hm^2时,药剂处理区雾滴沉积总密度可达44. 8～60. 7个/cm^2,在飞行边界2. 5、5. 0 m处雾滴密度分别为3. 0～4. 3、1. 0～1. 4个/cm^2;当草铵膦有效成分用量为750～1 500 g a. i./hm^2时,施药后14 d植保无人机对杂草和叶菜残茬总体株防效达94. 2%～97. 3%,鲜质量防效达95. 8%～98. 4%。同等施药剂量下,不同施药方式或不同喷液量处理对杂草或叶菜残茬的防效无显著性差异。

稻田苗后茎叶处理剂混用的联合除草作用

为明确稻田常用苗后茎叶处理剂混合使用对常见杂草防效的影响,采用温室盆栽法测定了氰氟草酯、噁唑酰草胺分别与灭草松、氯氟吡氧乙酸异辛酯混用对杂草的鲜重防效,并用Gowing法判断其联合作用类型。结果表明,灭草松可降低氰氟草酯对稗草和马唐及噁唑酰草胺对牛筋草和马唐的防效,氯氟吡氧乙酸异辛酯可提高氰氟草酯对稗草和马唐及噁唑酰草胺对马唐的防效,氰氟草酯和噁唑酰草胺对灭草松或氯氟吡氧乙酸异辛酯防控丁香蓼的防效无明显影响。灭草松与氰氟草酯或噁唑酰草胺混用对稗草、牛筋草、马唐和丁香蓼的联合作用类型为加成或拮抗作用;氯氟吡氧乙酸异辛酯与氰氟草酯或噁唑酰草胺混用对稗草、牛筋草、马唐和丁香蓼的联合作用类型为加成或增效作用。

火焰灭草技术在果园中的应用效果

为探明高温火焰在果园除草中的应用前景,利用1台自制的火焰设备,比较分析不同液化石油气(LPG)剂量下火焰处理对果园常见一年生杂草的防除效果。结果表明,牛筋草对火焰的敏感性低于阔叶杂草皱果苋和苦蘵;随着杂草叶龄的增加,火焰处理对杂草的防除效果总体降低;处理后7 d,LPG剂量为52.5~87.5 kg/hm^2时,火焰处理对6叶期之前的杂草株防效达80.6%~96.1%,对10叶期之后的杂草株防效为41.5%~79.4%,LPG剂量为122.5~175.0 kg/hm^2时,火焰处理对各类杂草株防效在77.6%~100.0%之间,鲜重防效在80.5%~100.0%之间。

Alleles contributing to acetyl coenzyme A carboxylase(ACCase)resistance in keng stiffgrass(Pseudosclerochloa kengiana)populations from China

Keng stiffgrass is a grass weed that affects wheat-rice cropping systems in China. The extensive reliance on acetyl coen- zyme A carboxylase （ACCase）-inhibiting herbicides has resulted in keng stiffgrass developing resistance to these herbicides. The objective of this research was to evaluate the resistance level of the putative resistant keng stiffgrass populations to ACCase-inhibiting herbicides and to identify their molecular resistance mechanism. Whole-plant dose-response experi- ments demonstrated that SD-4 （R）, SD-11 （R）, and JS-25 （R） populations were highly resistant to fenoxaprop, clodinafop, and fluazifop, moderately resistant to diclofop, had low resistance to sethoxydim and pinoxaden, but were sensitive to clethodim. Partial chloroplasticACCase sequences showed that there were two copies ofACCase gene in keng stiffgrass, and all homoeologous genes were expressed. The results of sequence analyses of the ACCase CT domain revealed an isoleucine-to-asparagine substitution at position 2041 in SD-4 （R） and SD-11 （R） populations, and a tryptophan-to-cysteine substitution at position 2027 in the JS-25 （R） population. To our knowledge, this is the first report of Ile-2041-Asn and Trp- 2027-Cys mutations in ACCase-resistant keng stiffgrass. In addition, three robust （derived） cleaved amplified polymorphic sequence （（d）CAPS） markers have been developed to rapidly identify these mutations in the ACCase gene of keng stiffgrass.

基于Pro-197-Ser突变的抗双氟磺草胺荠菜的快速检测

双氟磺草胺是防除小麦田荠菜(Capsella bursa-pastoris)等阔叶杂草的主要除草剂品种之一,目前在我国河南、河北、天津等地已有荠菜种群对其产生了抗药性。乙酰乳酸合成酶(ALS)基因第197位位点核苷酸突变是荠菜对双氟磺草胺产生抗药性的主要原因,通过在引物D197F序列的3′端引入错配碱基,设计出一种衍生性酶切扩增多态性序列(dCAPS)分子标记方法,可用于第197位位点核苷酸突变的快速检测。抗药性及敏感荠菜的ALS基因扩增片段经限制性内切酶AvaⅡ酶切后表现出多态性,敏感荠菜产生了31、192 bp等2个片段;抗药性荠菜产生了31、192、223 bp等3个片段。该方法检测结果准确、可靠,与整株水平测定结果一致,并适用于第197位位点的任意氨基酸取代。这种dCAPS分子标记方法可对田间当季杂草进行检测,可为荠菜种群抗药性的快速检测与监测提供理论支持。

Transcriptomic analysis reveals the transcription factors involved in regulating the expression of EPSPS gene,which confers glyphosate resistance of goosegrass (Eleusine indica)

Glyphosate inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase(EPSPS)and overexpression of the EPSPS gene is one of the molecular mechanisms conferring glyphosate resistance in weeds.A regulatory sequence of EPSPS gene was isolated previously,and an alteration in its 5´-untranslated region(UTR)pyrimidine(Py)-rich stretch element is involved in the regulation of EPSPS expression in glyphosate-resistant(GR)Eleusine indica.However,the transcription factors involved in this regulatory sequence remain to be elucidated.In this study,we investigated the regulatory network of EPSPS overexpression associated genes in a GR E.indica population by RNA-seq.The differentially expressed transcript analyses revealed that glyphosate treatment caused an increase in the expression of 2752 unigenes and a decrease in the expression of 4025 unigenes in the GR E.indica,compared to the glyphosatesusceptible(GS)E.indica.Among them,1373 unigenes were identified to be co-expressed with the EPSPS gene in GR E.indica.GO and KEGG pathway analyses showed that the up-regulated unigenes were mainly enriched in chloroplasts and associated with the shikimate biosynthesis pathway,chlorophy II and peroxisome metabolism processes.Notably,the expression of a Shikimate kinase which catalyzed the conversion of Shikimate to Shikimate 3-phosphate(S3P,a substrate of EPSPS),was also up-regulated.Eight transcription factors were identified as likely to be involved in the regulation of the EPSPS expression,and three of them(ARF2,ARF8 and BPC6)showed more binding sites because of a(CT)n insertion of the 5´-UTR Py-rich stretch element in GR.However,the yeast one-hybrid assay illustrated that ARF8 and BPC6 could bind to the 5´-UTR Py-rich stretch element of wild type EPSPS,but could not bind to the mutated form.Our data suggests that the transcriptional regulation of EPSPS expression is complex and was significantly altered in GR E.indica.These discoveries provide new references for further study of the EPSPS overexpression mechanism that endows glyphosate resistance.

30%烟嘧磺隆·莠去津·硝磺草酮可分散油悬浮剂对甜玉米田杂草的防效及安全性

研究30%烟嘧磺隆·莠去津·硝磺草酮可分散油悬浮剂在甜玉米田的应用效果,在甜玉米不同叶龄期开展田间试验,评价其对杂草的防除效果及对甜玉米的安全性。结果表明,30%烟嘧磺隆·莠去津·硝磺草酮可分散油悬浮剂在甜玉米3~4叶期或6~7叶期施药,900~1575 g a.i./hm^2剂量范围内对甜玉米品种粤甜28安全,对玉米田常见杂草凹头苋、光头稗、马唐和香附子的防效及增产效果均显著高于对照药剂38%莠去津悬浮剂2160 g a.i./hm^2播后苗前处理。推荐30%烟嘧磺隆·莠去津·硝磺草酮可分散油悬浮剂在900~1350 g a.i./hm^2范围内,甜玉米3~5叶期茎叶喷雾使用。