水田稗草发生规律及对水稻产量的影响研究

用小区试验的方法，研究稗草发生规律及不同时期除草对水稻产量的影响，结果表明，耙地越早，稗草高峰期出现越早，稗草发生数量越多：耙地越晚，稗草高峰期出现也推迟，稗草发生数量减少。除草时间推迟，稗草数量增加、长势旺，对水稻产量影响加重。     

大气CO2浓度升高条件下移栽水稻与不同出苗时间稗草竞争的响应差异

通过田间试验,研究了FACE（开放式空气CO2浓度升高）条件下,移栽稻田水稻（Oryza sativa）与不同发生时期稗草（Echinochloa crusgalli）生长和竞争的响应差异。结果显示,FACE条件下水稻与稗草比例为1∶1时,水稻分蘖、生物量和产量均增加,而稗草则减少。水稻与移栽稻田本田萌生稗草的生物量比率增加181.7%、产量比率增加259.7%、茎蘖比率增加24.2%、有效分蘖比率增加186.3%,水稻竞争优势增加,而移栽稻田本田萌生稗草竞争能力下降。水稻与秧田萌生稗草的竞争关系变化趋势在营养生长期与上述情况相同,但进入生殖生长后水稻竞争优势不再显著,FACE条件下与秧田萌生稗草竞争的水稻最终生物量和产量分别增加22.7%和8.2%,但秧田萌生稗草的最终生物量和产量也增加了11.9%和9.5%。水稻与秧田萌生稗草的生物量比率、茎蘖比率和产量比率增加均不显著。 可见,田间大气CO2浓度升高条件下水稻与稗草的竞争关系发生的变化与稗草发生时期有重要关系。     

17%稻草净防除移栽稻田杂草的试验

用１７％稻草净在移植稻田除草的试验结果表明，它对稗草，莎草和阔叶杂草等具有较高的防除效果，水稻安全，各试验剂量对水稻产量增产幅度均在３２％以上。     

黑龙江省垦区移栽稻田杂草防除策略

黑龙江垦区地处中国东北边陲 ,水稻生育主要受延迟性低温和早霜影响 ,农时至关重要 ,除草剂安全性影响水稻产量、品质和经济效益 ,在除草剂的选择上应首先把安全性放在首位。垦区水田稗草 (Echinochloacrusgalli)、多年生莎草科的扁秆藨草 (Scirpusplaniculmis)、日本藨草 (Scirpusnipponocum)等发生早且发生时期长 ,经多年试验及生产实践 ,防治稗草插后早期使用的莎稗磷 (anilofos)、苯噻草胺 (mefenacet)、环庚草醚 (cinmethylin)、丙草胺(pretilachlor)、稻思达 (oxadiargyl)、杀草丹 (thiobencarb)等 ,于水稻插前 3～ 7d ,插后 15～ 2 0d分期施药 ,药效稳定 ,对水稻安全 ;防治扁秆藨草、日本藨草使用吡嘧磺隆 (pyrazosulfuron ethyl)、苄嘧磺隆 (bensulfuron methyl)、环胺磺隆 (cyclosulfamuron)、醚磺隆 (cinosulfuron)、乙氧磺隆 (ethoxysulfuron) ,插前和插后分期施药 ,药效稳定。根据稻田杂草群落选择适宜的混配除草剂品种可获得好的除草效果和经济效益     

黑龙江省垦区移栽稻田杂草防除策略

黑龙江垦区地处中国东北边陲，水稻生育主要受延迟性低温和早霜影响，农时至关重要，除草剂安全影响水稻产量，品质和经济效益，在除草剂的选择上应首先把安全性放在首位。垦区水田稗草（Ecirpus nipponocum）等发生早且发生时期长，经多年试验及生产实践，防治稗草插后早期使用的莎稗磷（anilofos）、苯噻草胺（mefenacet）、环庚草醚（cinmethylin）、丙草胺(pretilachlor）、稻思达(oxadiargyl）、杀草丹（thiobencarb）等，于水稻插前3-7d，插后15-20d分期施药，药效稳定，对水稻安全；防治扁秆lu草、日本lu草使用吡嘧磺隆（pyrazosulfuron-ethyl）、苄嘧磺隆（bensulfruon-methly）、环胺磺隆（cyclosulfamuron）、醚磺隆（cinosulfuron）、乙氧磺隆（ethoxysulfuron），插前和插后分期施药，药效稳定。根据稻田杂草群落选择适宜的混配除草剂品种可获得好的除草效果和经济效益。     

20%氰氟草酯+5%氟嘧啶草醚可分散油悬浮剂对寒地水稻田稗草的防治效果及安全性研究

稗草是寒地水稻田的恶性杂草,一般除草剂对其防治很不理想,为了解决这一问题,在2017年采用一种自主研发的具有除草活性的氰氟草酯和氟嘧啶草醚复配剂对水稻田不同叶龄稗草进行防除试验。通过对水稻苗期安全性、大田的安全性、除草效果等项目的调查,结果表明:试验药剂20%氰氟草酯+5%氟嘧啶草醚可分散油悬浮剂可有效控制水稻田稗草危害,对不同叶龄稗草用药后15 d的防效均达到90%以上,最适使用剂量可为100~120 ml/667 m~2,同时该除草剂对水稻安全,是一种新型、安全、绿色的除草剂。     

除草剂低剂量处理的高产效果

 为了比较常规剂量和低剂量除草剂对稻田稗草、丛生千金子、碎米莎草、红根莎草和鳢肠的防除效果及其对产量的影响,在水稻和杂草的不同生长阶段以常规剂量和低剂量(口恶)草丙分别作单、连续和结合敌稗复合式处理。早期使用敌稗,随后在水稻3叶期使用低剂量(口恶)草丙0,08或0.11kgai/ha 处理,均获得优级杂草防除率和最高水稻产量。(口恶)草丙单一或连续使用能有效防除稗草和丛生千金子,但不能防除莎草和鳢肠。(口恶)草丙低剂量和常规剂量处理分别发生轻微和中度水稻植株损伤,但处理后19天,水稻恢复正常。     

盐碱洼地直播稻田杂草发生规律及防除技术

吉林省中西部盐碱洼地水稻直播稻田草害非常严重,因而影响了直播水稻的发展。1985～1988四年时间里,作者对该地区杂草发生规律进行了大量的调查研究,确认该地区直播稻田主要杂草有7科16种,其中危害极重的有3种,局部危害的有5种,分布普遍、危害轻的有8种。并明确了①开荒种稻三年以上的地杂草基本形成水田立体群落。②水稻生育期间杂草发生的三次高峰期是6月上中旬,稗草发生总量达45～75％;6月中下旬,扁杆藨草达总发生量的42～73％,慈菇、泽泻等达60～84％;7月初眼子菜、小茨藻发生量达总量的79～87％。③稗草种子广泛分布于5厘米土层中,1.5厘米以上的种子量占90％,萌发早、出苗快,危害最大;扁杆蔗草平均每平方米块茎达886.75个,15厘米以下块茎占93.4％。7月5日之前发生量占总量的72.11％。④根据直播稻田草的发生规律,确定最佳的防治时期及最优的配方4个,除草效果均在90％以L。     

秧田清防除水稻秧田杂草药效试验

采用田间小区药效试验和大田示范相结合的方法，探讨适应于水稻秧田的除草新制剂——秧田清的除草效果。结果表明，秧田清可有效防除秧田稗草、常见莎草和阔叶草，是一种高效、广谱、安全的除草剂新制剂。     

除草剂、杀菌剂的选择及药害的补救

１除草剂的选择近十年来，黑龙江省农垦总局植保站组织农药联网试验，对除草剂安全性进行系统评价，结论是水稻除草剂安全性直接影响水稻产量和品质。防除稗草最安全的是禾大壮、千金，其次是杀草丹、拜田净、瑞飞特、阿罗津、苯噻草胺、农思它、快杀稗，最差的是丁草胺。防阔叶杂草的除草剂最安全的是草克星（草灭草、草威、吡嘧磺隆）、农得时、威农、金秋、太阳星、排草丹，最差的是２甲４氯及２甲４氯的混剂。应注意９０％杀草丹乳油适用于南方、北方旱育苗床封闭除草用５０％杀草丹乳油安全有效。垦区属寒温带大陆性气候，其中五至六月…     

谷子新品系抗除草剂试验

通过对抗除草剂阿特拉津谷子新品系DSB98-625SR喷施不同剂量的除草剂试验，结果表明各处理与对照比较具有一定的增产作用；而以2.25kg/hm^2除草效果与产量为最佳。目前我们巳进行杂交育种，预期选育出较为理想的抗除草剂阿特拉津的谷子新品系应用于生产。     

Interaction of genotype × management on vegetative growth and weed suppression of aerobic rice

Water shortage in drought-prone rice-growing areas of the world is threatening conventional irrigated rice production systems, in which rice is transplanted into fields where standing water is maintained until harvest. Aerobic rice production systems, in which rice is grown as a direct-seeded upland crop without flooding, require less water than conventional systems, but the transition to aerobic rice systems is impeded by severe weed infestation. An environmentally friendly and less labor-intensive weed control method needs to be introduced to aerobic rice farmers. A study was conducted at the International Rice Research Institute in the 2003 wet season and 2004 dry season to evaluate the effects of genotype, seeding rate, seed priming and their interactions on vegetative growth, yield and weed suppression. Three contrasting aerobic rice genotypes differing in yield and weed-suppressive ability (WSA) were grown at three seeding rates (100, 300 and 500 viable seeds m⁻²) with or without seed priming under two weed management treatments (weed-free and weedy) in a split-plot design. In 2004, the overall weed pressure was higher than in 2003, and consequently treatment effects in this year were more distinct than in 2003. No significant interactions among the experimental factors were found for crop yield, weed biomass, leaf area index, tiller number and vegetative crop biomass. Raising seeding rate from 100 to 300 viable seeds m⁻² resulted in a significant increase in yield and a decrease in weed biomass, whereas a further increase from 300 to 500 viable seeds m⁻² did not result in a further improvement in yield and weed suppression. The stronger WSA of genotype Apo than that of genotypes IR60080-46A and IRAT 216 related to a stronger competitive ability of individual plants and a faster canopy closure (0.5–6 days earlier). The WSA of weakly competitive genotypes was partially compensated for by a higher seeding rate. Seed priming, which was only evaluated in 2003, accelerated emergence by 2 days and slightly enhanced early crop growth, but had no significant effect on yield and weed suppression. The present study suggests that combining a weed-suppressive genotype with an optimum seeding rate can serve as a tool to manage weeds.     

玉米专用除草药肥的药效及对产量影响的研究

针对辽宁省地区玉米田常见杂草种类,选择对其防除有效的农药,与复合肥按照一定配比制作成玉米专用包膜药肥和包裹药肥。通过田间试验,对两种药肥的药效和农药残留以及作物产量进行了深入研究。结果表明：玉米专用药肥在田地中一次完成作物的除草和施肥任务,能保持药效的发挥并提高肥效,促进作物生长。包膜药肥的施用效果要好于包裹药肥和常规施肥。其中包膜药肥处理E杂草总鲜重防效较常规施肥处理B提高了21．34％;大田试验包膜药肥处理较常规施肥施农药处理B对照增产11．6％,其中E处理最高,增产12．1％,增收1800元／hm^2。     

Effect of Establishment Methods and Weed Management Practices on Some Growth Attributes of Rice

In rice, the traditional system of transplanting gives the crop a 14 to 21-day growth advantage over the weeds [1]. The transplanting also enables rice to capture space earlier. This is because the young rice plants have leverage over germinating weeds due to shading and earlier establishment of root system. The immediate flooding after transplanting limits the establishment of many weeds [2]. Similarly, in direct seeded method, the use of high seed rates could reduce weed infestation to a lar…     

Yield loss prediction models based on early estimation of weed pressure

Weed control thresholds have been used to reduce costs and avoid unacceptable yield loss. Estimation of weed infestation has often been based on counts of weed plants per unit area or measurement of their relative leaf area index. Various linear, hyperbolic, and sigmoidal regression models have been proposed to predict yield loss, relative to yield in weed free environment from early measurements of weed infestation. The models are integrated in some weed management advisory systems. Generally, the recommendations from the advisory systems are applied to the whole field, but weed control thresholds are more relevant for site-specific weed management, because weeds are unevenly distributed in fields. Precision of prediction of yield loss is influenced by various factors such as locations, yield potential at the site, variation in competitive ability of mix stands of weed species and emergence time of weeds relative to crop. The aim of the review is to analyze various approaches to estimate infestation of weeds and the literature about yield loss prediction for multispecies. We discuss limitations of regression models and possible modifications to include the influential factors related to locations and species composition in context of their implementation in real time patch spraying.     

The critical period for weed competition in French bean (Phaseolus vulgaris L.) in Mediterranean areas

Field experiments were carried out in 2004 and repeated in 2005 and 2006 in central Italy to determine the effect of competition from a natural weed flora on growth and yield of French bean (Phaseolus vulgaris L.). Two treatments were applied; weeds were either allowed to infest the crop or plots were kept weed free for an increasing duration of time (0, 7, 21, 28, 35, 45 days) after crop emergence. To assess the critical period of weed competition (CPWC) and the influence of weed infestation on yield, the Gompertz and logistic equations were fitted to data which represented the increasing duration of weed-free and weed-infested periods, respectively. During the three years of the experiment weeds, allowed to interfere for the whole growing season, reduced fresh pods yields up to 60%, 65% and 59% of the weed-free bean plots. Based upon an arbitrary yield loss (AYL) of 5%, the CPWC was from 50 Growing Degree Days (GDD) to 284 GDD, i.e. from 11 days after emergence (DAE) to 28 DAE. These values correspond to the lowest and highest values observed in the three experiments respectively for the weed-infested and weed-free period.     

Effect of herbicides on weed management in dry-seeded rice sown under different tillage systems

In India, dry-seeded rice (DSR) production systems are rapidly replacing conventional rice production systems due to various advantages. DSR systems can be managed under zero-till (ZT) conditions or after a preparatory tillage, often referred to as conventional tillage systems (CONT). Although previous reports indicate the contribution of tillage to weed suppression, the effect of one-time preparatory tillage in a DSR system could vary depending on the dominant weeds in the system, vertical seed distribution and the weed seed dynamics. A study was conducted to test the efficacy of ZT and CONT and their interaction with herbicide treatments on the weed population dynamics and rice grain yield in 2010 and 2011. Tillage systems did not affect weed emergence, weed biomass, tiller production and crop yield. However, herbicide treatments varied in their efficacy on individual weeds. Hand-weeding treatments and pendimethalin combined with hand weeding did not effectively control Cyperus rotundus L. and Panicum maximum Jacq. (a perennial grass weed with underground parts). The herbicide combination of metsulfuron and chlorimuron was effective in controlling C. rotundus but not grass weeds. This indicates the need for sequential applications of herbicides for grass weed control or integration of hand weeding to achieve broad-spectrum weed control. Apart from hand weeding (three times), treatment with penoxsulam–cyhalofop and pendimethalin followed by (fb) hand weeding resulted in low weed density, high tiller production and grain yield. The study clearly indicates that tillage does not always lead to weed suppression compared with ZT, and herbicides must be chosen based on the dominant weeds in a system. The results of this study are pertinent as herbicide-resistant weeds are rapidly evolving under continuous herbicide selection pressure, which warrants studies on enhancing productivity through low-input, environmentally friendly and sustainable production technology.     

Model of wheat yield response to application of diclofop-methyl to control ryegrass (Lolium rigidum)

A general model of crop yield response to herbicide application is proposed. The model includes three components: the effect of herbicide dosage on weed density, the effect of surviving weed density on crop yield and the effect of herbicide directly on the crop. The model is used to estimate the response of wheat yield to application of diclofop-methyl to control ryegrass (Lolium rigidum) in Australia. It is found that the competitiveness of ryegrass plants surviving treatment is reduced by the treatment and that the proportion of yield loss at a given ryegrass density is not independent of the absolute weed-free yield. The response function is used to calculate economic thresholds and optimal herbicide dosages.     

Weed pressure level and the correlation between weed competitiveness and rice yield without weed competition: An analysis of empirical data

Improving rice (Oryza spp.) competitiveness against weeds would provide a low-cost and safe tool for an integrated weed management strategy. This paper addresses the underlying causes of tradeoff between yield without weed competition and weed competitiveness. Rice yield or weed biomass under weedy conditions are used as indicators of weed competitiveness. For this analysis, a common database was compiled from the results of 45 concurrent field trials comparing the performance of four to 64 genotypes in weed-free and weedy conditions in Asia, West Africa, North America and Latin America. Cyperus spp., Echinochloa spp. and Eleusine indica were the most frequent dominant weed species, being found in 9, 20 and 7 trials, respectively. Mean relative yield reduction [(yield under weed-free conditions − yield under weedy conditions)/yield under weed-free conditions] across genotypes tested for each trial was defined as weed pressure level. Mean yield without weed competition across genotypes ranged from 1.8 to 11.6 t ha⁻¹ with mean relative yield reduction from almost 0 to 91%. Correlations for rice yield between weed-free and weedy conditions were generally positive, and significant in 27 trials. The correlations were related to weed pressure level and dominant weed species, but not to ecosystem (upland or lowland) or yield level under weed-free conditions. Relative yield reduction had a more pronounced effect than dominant weed species. Correlation decreased as weed pressure level increased, and became negative when relative yield reduction exceeded 80%, suggesting that different morpho-physiological mechanisms are responsible for high yields under weed-free conditions or severe weed competition. Correlations between rice yield under weed-free conditions and weed biomass varied, giving 17 and 19 for positive and negative ones, respectively. These correlations were related neither to weed pressure level, ecosystem and yield level under weed-free conditions, nor to dominant weed species. These results indicate that correlations between rice yields under weed-free and weedy conditions can be strongly affected by weed pressure level, and, unless severe weed competition occurs, there appears to be no tradeoff between them. Association of morpho-physiological mechanisms with weed competitiveness under conditions differing in weed pressure levels and dominant weed species deserves further investigation.