Effects of drought on weed emergence and growth vary with the seed burial depth and presence of a cover crop

In conservation agriculture, weed seed germination could decrease with the presence of a cover crop, surface weed seed location and temporal drought in summer just after seed shedding. This study simultaneously examined the effects of a cover crop, burial depth (seed location) and hydric stress on weed emergence and early growth. It was hypothesized that drought would reduce weed emergence and the initial growth of weed seeds and that this effect would be greater when the seeds were on the soil surface and in the presence of a cover crop. Four annual weed species were chosen that are frequently found (Anisantha sterilis, Vulpia myuros, Sonchus asper, Veronica persica) and not frequently found (Alopecurus myosuroides, Poa annua, Cyanus segetum, Capsella bursa‐pastoris) in fields that implement conservation agriculture. The unburied seeds had 26% lower emergence, on average, than the buried seeds (significant for six of the eight species), hydric stress reduced emergence by 20% (for seven of the eight species) and the presence of a cover crop reduced the level of emergence by 17% (for all species). The unburied seeds with hydric stress were emerging under the “most stressful” set of factors, with a 45% decrease in emergence, compared with the seeds emerging under the “least stressful” set of factors (buried seeds without hydric stress). All the weed growth measurements (height, dry matter content and number of leaves) decreased with the presence of a cover crop. The species that are found frequently in the fields that implement conservation agriculture, compared with the species that are not frequently found in conservation agriculture fields, had higher rates of germination and a higher tolerance of hydric stress when their seeds were unburied.     

浅谈优良草坪草种的选择及草坪杂草的危害

草坪杂草是草坪生产栽培的大敌,本文列举了草坪杂草的主要危害,重点从栽培措施、 人工除草或机械除草、化学除草剂防除杂草几个方面介绍了草坪杂草的防除技术,以供园林工作 者在草坪养护时借鉴。     

新疆移栽稻田杂草不同防除方式药效评价

【目的】通过水稻移栽前土壤封闭处理和移栽后茎叶喷雾处理,筛选对移栽稻田杂草具有较好防效的除草剂,为安全高效应用除草剂提供依据。【方法】采用随机区组的方法,定点取样调查各处理小区的杂草株数、鲜重,评价供试药剂对杂草防除效果及对移栽水稻安全性。【结果】40%五氟·丁草胺悬浮剂750 g a.i./hm²+30%苄嘧磺隆可湿性粉剂67.50 g a.i./hm²、500 g/L丙草胺乳油525 g a.i./hm²+30%苄嘧磺隆可湿性粉剂67.50 g a.i./hm²和60%丁草胺乳油1 260 g a.i./hm²+30%苄嘧磺隆可湿性粉剂67.50 g a.i./hm²在水稻移栽前进行土壤封闭处理,20 d后施用25 g/L五氟磺草胺可分散油悬浮剂30 g a.i./hm²+30%苄嘧磺隆可湿性粉剂45 g a.i./hm²进行茎叶喷雾处理,对移栽稻田一年生杂草的株防效均在89%以上,鲜重防效在97%以上。仅施用3%氯氟吡啶酯乳油36 g a.i./hm²进行茎叶喷雾处理,药后45 d对稗草和空心莲子草的防效达到100%,对移栽稻田一年生杂草的株防效和鲜重防效均在91%以上。【结论】针对稻田扁秆藨草、稗草和空心莲子草危害为主的田块,可选用500 g/L丙草胺乳油或40%五氟·丁草胺悬浮剂或60%丁草胺乳油与30%苄嘧磺隆可湿性粉剂混配进行土壤处理,且20 d后选用25 g/L五氟磺草胺可分散油悬浮剂+30%苄嘧磺隆可湿性粉剂进行茎叶喷雾处理。若不进行土壤封闭处理的田块,针对稗草和空心莲子草危害为主的田块,可选用3%氯氟吡啶酯乳油进行茎叶喷雾防除。     

室内模拟旱直播稻田环境下齐整小核菌Sclerotium rolfsii菌株SC64致病力的影响因子及除草效果的研究

本文通过温室盆栽试验,以鳢肠Eclipta prostrata为例,研究杂草叶龄、不同含菌丝体基质接种量以及温度、土壤湿度、保湿期时间等环境因子对菌株SC64侵染鳢肠的影响。在此基础上,温室条件下模拟旱直播水稻田环境下菌株SC64防治节节菜Rotala indica、异型莎草Cyperus difformis、鸭舌草Monochoria vaginalis和耳叶水苋Ammannia arenaria的试验。结果表明,鳢肠幼苗在5叶期以下,接种含菌丝体固体基质剂量在100g m 2以上,温度范围27～33℃,土壤相对饱水90%左右,并且接菌后湿度保持至少24 h,是菌株SC64达到理想除草效果的必需条件。温室模拟试验结果显示,接种含菌丝体固体基质剂量在120 g m 2时,28 d可引起节节菜和鸭舌草81%和74%的植株死亡率及83.8%和82.5%的鲜重抑制率;对异型莎草和耳叶水苋的防效稍差,仅能引起约50%的植株死亡率及60%～65%的鲜重抑制率。这表明菌株SC64可有效控制阔叶杂草,具有开发作为生物除草剂的潜力。     

广西麦冬草坪杂草调查及药剂防除试验

2014-2015年对广西6个主要城市麦冬草坪杂草调查结果表明,麦冬草坪常见杂草有30科107种,其中菊科最多,有22种,占总数的20.56%,其次是禾本科13种,占总数的12.15%。危害较严重的有15种,依次为白花鬼针草、狗牙根、马唐、胜红蓟、香附子、铺地黍、阔叶丰花草、双穗雀稗、积雪草、龙葵、光鳞水蜈蚣、红花酢浆草、小飞蓬、银胶菊和升马唐。药剂防除试验结果表明,24%甲咪唑烟酸AS 324g/hm2、75%甲嘧磺隆WG 270g/hm2、50%丁噻隆SC 4 500g/hm2处理总草防效达80.37%~85.13%,对麦冬的抑制率达31.69%~70.91%;4%烟嘧磺隆SC180g/hm2、20%氯氟吡氧乙酸EC 360g/hm2+4%烟嘧磺隆SC 90g/hm2、5%精喹禾灵EC 90g/hm2+10%双草醚WP 90g/hm2、50%丁噻隆SC 2 250g/hm2+20%氯嘧磺隆WP 22.5g/hm2、75%甲嘧磺隆WG 135g/hm2+24%乙氧氟草醚EC 337.5g/hm2总草防效达81.07%~96.07%,对麦冬的抑制率为1.53%~8.46%。75%甲嘧磺隆WG 135g/hm2+24%乙氧氟草醚EC 337.5g/hm2总草防效达96.07%,对麦冬的抑制率为3.31%,适用于麦冬草坪杂草防除。     

淮河流域小麦田主要杂草及其防除

淮河流域是我国优质冬小麦的主要生产基地，近年来麦田杂草发生数量及草相都发生了一定变化。农民在化学防除中却存在一些误区，甚至造成不同程度的药害。本文就该流域冬小麦主要杂草及其在化学防除中存在的问题作了阐述．力求帮助广大农民朋友提高除草剂的使用水平，为小麦丰收打下坚实的基础。     

东北地区四种常见禾本科杂草病原真菌资源调查及其致病性测定

为了解我国东北地区常见禾本科杂草病原真菌资源状况,于禾草生长季节对东北三省19个县市的稗草、狗尾草、马唐和虎尾草的发病情况进行了调查和采样。对病害样品用组织分离法分离获得186个真菌菌株,经形态学观察和rDNA ITS序列比对分析,鉴定到10个属的真菌。对其中分离率较高具代表性的或来自发病严重样品的31个菌株用人工接种法进行了致病性测定,明确了新月弯孢(Curvularia lunata)对稗草、狗尾草、马唐和虎尾草均有较强致病性,梭形凸脐蠕孢(Exserohilum fusiforme)和尖角凸脐蠕孢(E. monoceras)对稗草具有较强致病性,麦根腐平脐蠕孢(Bipolaris sorokiniana)、狗尾草平脐蠕孢(B. setariae)、嘴突凸脐蠕孢(E. rostratum)和链格孢(Alternaria spp.)对狗尾草具有较强致病性。不同菌株致病性有差异,一般来讲,对原寄主的致病性强于对其他寄主的致病性。研究结果丰富了禾草的病菌资源和信息,为真菌除草剂的研发奠定了基础。     

蒜田杂草生态经济阈值研究

研究了不同杂草密度对蒜薹和蒜头产量的影响,建立了产量损失与杂草密度关系方程:y=0.000 05x2+0.008 3x+0.16。根据防治经济学原理,研究得出杂草经济危害损失允许水平为0.62%,从而确定蒜田杂草生态经济阈值为43.84株/m2,在此阈值以下,可不施药。     

抗草甘膦转基因大豆‘ZH10-6’对田间生物多样性的影响

转基因大豆新品种在商业化之前必须进行环境安全评价,其中,转基因大豆对田间生物多样性的影响是环境安全评价的重要组成部分。本研究以转G2-EPSPS和GAT双价基因的抗草甘膦大豆‘ZH10-6’及其受体大豆‘中黄10’为材料,于2019年在北京顺义地区进行了大田试验,调查了不同处理对节肢动物多样性、主要病害发生、根瘤菌及杂草多样性的影响。结果表明:与非转基因大豆‘中黄10’相比,转基因大豆‘ZH10-6’不同处理田间节肢动物物种丰富度、Shannon-Wiener多样性指数、Simpson优势集中性指数、Pielou均匀性指数无显著差异;大豆霜霉病与病毒病的发病率和病情指数无显著差异;根瘤数差异不显著,大豆田杂草多样性无显著差异。研究结果为抗草甘膦转基因大豆‘ZH10-6’的环境安全性评价提供了依据。     

精氟·胺苯·草除灵WP防除油菜田杂草试验

研究了14.5%精氟·胺苯·草除灵WP对油菜田杂草看麦娘和牛繁缕的防治效果.试验结果表明,2月份施药的效果优于12月份的效果;施药后第60天的综合密度防效为88.50%～94.26%:对照药剂高效氟吡甲禾灵对看麦娘的防效为91.26%,但对牛繁缕基本无效,30%草除灵SC对看麦娘无效,但对牛繁缕的防效为92.93%.复配剂的综合密度防效显著高于草除灵和高效氟吡甲禾灵,通过复配,提高了油菜生产的安全性,增产效果极其显著.