Effect of Pretilachlor on Weedy Rice and Other Weeds in Wet-Seeded Rice Cultivation in South Vietnam

Abstract

Wet-seeded rice is a common method of sowing in Vietnam. Weeds, including weedy rice, however, are a major problem in this establishment method. A study was conducted in a farmer’s field to evaluate the effect of pretilachlor dose (0, 300, 600, and 900 g ai ha^–1) on the management of weedy rice and other weeds in wet-seeded rice cultivation in the spring-summer, summer-autumn, and winter-spring seasons of 2012-13. The herbicide was applied 1 day after sowing. Weeds belonging to the grass, broadleaf, and sedge groups were effectively controlled by the lowest herbicide dose (300 g ha^–1). Overall, weed control did not increase with increases in herbicide dose after 300 g ha^–1, suggesting the optimum dose for pretilachlor in wet-seeded systems. The application of pretilachlor at 300 g ha^–1 significantly reduced the number of weedy rice panicles (20 – 69%) and weedy rice biomass (15 – 26%). The highest pretilachlor dose (i.e., 900 g ha^–1), however, was better than the lower doses in reducing the number of weedy rice panicles (47 – 80%) and weedy rice biomass (41 – 54%). The non-treated plots produced a rice grain yield of 210, 2000, and 1850 kg ha^–1 in the spring-summer, summer-autumn, and winter-spring seasons, respectively. Compared with the non-treated plots, the lowest dose of pretilachlor improved grain yield. However, maximum yield was obtained by applying the highest dose of pretilachlor; 2690, 4490, and 5150 kg ha^–1 in the spring-summer, summer-autumn, and winter-spring seasons, respectively. The results of our study suggest that a broad spectrum of weed flora can be easily managed by a lower dosage of pretilachlor in wet-seeded rice; however, the herbicide dose needs to be increased to 900 g ha^–1 in order to decrease the weedy rice problem.     

棉田不同杂草群落对棉花生长和产量的影响

于2011～2012年在山东省茌平县棉田中人为设置无草区和禾本科杂草、莎草科杂草、阔叶类杂草、混合杂草自然发生区,研究了不同杂草群落对棉花生长和产量的影响。结果表明,禾本科杂草区以牛筋草[Eleusine indica(L.)Gaertn.]为主,总密度为338.75～505.13茎/m2,棉花产量损失为69.7%～69.8%;莎草科杂草区以异型莎草(Cyperus difformis L.)为主,杂草密度为260.75茎/m2,产量损失为57.7%～59.4%;阔叶类杂草区以藜(Chenopodium album L.)、醴肠[Eclipta prostrata(L.)L.]为主,杂草总密度为208.25～316.0茎/m2,产量损失为87.5%～88.9%;混合杂草区杂草群落2011年主要以藜、醴肠、牛筋草等为主,2012年以牛筋草、异型莎草为主,总密度为366.00～410.0茎/m2,产量损失达90.5%～90.7%。以杂草单茎危害率衡量不同类型杂草对棉花产量损失的影响依次为阔叶类杂草>莎草科杂草=禾本科杂草。杂草危害直接影响棉花生长,对棉花产量构成因素均有影响,其中对棉花成铃数影响最大,杂草生长区比无草区成铃数减少45.2%～87.3%,果枝数减少21%～64%,单铃重减少6.7%～24.5%。此外,杂草的生长也直接威胁到棉花植株的保苗效果。     

黑龙江省主要阔叶树种绿枝扦插的效果

2001年,在带岭林科所四公里落叶松种子园塑料大棚内进行了10个树种、3个采穗时期、3种插穗处理和15种基质1350个组合的绿枝扦插试验,结果表明：同一树种的不同采条时期、不同扦插处理、不同基质和不同树种的同一采条时期、同一扦插处理、同一基质的生根效果有差异,并有明显的交互作用。统计得出各树种最佳组合的生根率：刺五加80％;五味子70％;紫椴40％;花楸30％;水曲柳20％;黄菠萝20％;山槐20％％;山梨10％;春榆10％;胡桃楸0。     

宽叶武竹的组培快繁技术研究

以宽叶武竹新发嫩枝上茎尖、茎段为材料,研究了不同的激素配比对其芽诱导、增殖和生根的影响。结果表明:芽诱导适宜培养基为MS+6-BA 0.5mg/L+KT 0.1mg/L,芽增殖适宜培养基为MS+6-BA0.3mg/L+KT 0.1mg/L,生根适宜培养基为1/2MS+IBA 1.0mg/L+NAA 0.2mg/L。在生根培养中采用5mm长的茎尖进行生根培养,生根率最高可达91.0%,生根苗的炼苗成活率达90.0%以上。     

氯吡·唑草酮WP对大麦田阔叶杂草的防效及安全性

为了明确34%氯吡·唑草酮WP对大麦田中的阔叶杂草猪殃殃、荠菜、泽漆、婆婆纳和大巢菜的防效以及对大麦的安全性,于2010～2011年进行了34%氯吡.唑草酮WP防除大麦田阔叶杂草的防效和安全性试验,结果表明:34%氯吡.唑草酮WP可用于防除大麦田中多种阔叶杂草,使用一次,基本可以控制大麦全生育期不受阔叶杂草危害,且杀草速度快,增产显著。在试验剂量范围内对大麦及下茬移栽棉花安全。建议用量:冬季在大麦3～4叶期、杂草2叶期450 g/hm2较为合适,春季在2月下旬至3月上旬大麦返青拔节前以450～600 g/hm2为宜。     

Discrimination of weed seedlings, wheat (Triticum aestivum) stubble and sunflower (Helianthus annuus) by near-infrared reflectance spectroscopy (NIRS)

The potential of using near-infrared reflectance spectroscopy (NIRS) to discriminate between seven broadleaf weed species, sunflower and wheat stubble was evaluated. Our results showed that the spectral window between 750 and 950 nm, which corresponds to near-infrared wavelength, was able to discriminate among wheat stubble, sunflower and the most problematic “hard-to-control” weeds in no-till sunflower, i.e. Little mallow (Malva parviflora L.) and Ecballium elaterium L. These results are promising for further work in real-time remote sensing identification of weed patches in sunflower fields.     

Use of propanil and quinclorac tank mixtures for broadleaf weed control on rice (Oryza sativa) levees

Broadleaf weed control on rice levees is an emerging problem faced by growers and consultants in Arkansas, USA. Field experiments were conducted at Lonoke and Stuttgart, Arkansas, in 2007 and 2008 to evaluate the effectiveness of various postemergence herbicides applied alone or in tank mixture with propanil or quinclorac for large-sized broadleaf weed control on rice levees. Rice injury was minimal (≤5%) from all herbicides at 2 weeks after treatment (WAT), and no injury was observed at 4 WAT. Sida spinosa (prickly sida) and Amaranthus palmeri (Palmer amaranth) were the most difficult-to-control weeds on levees. Of the herbicides applied alone, 2,4-D generally supplied the highest and most consistent weed control across the six species evaluated. Quinclorac was generally a better tank-mix partner than propanil for control of the weed spectrum evaluated. Propanil at 4.48 kg/ha lowered the activity of several systemic herbicides on S. spinosa, Polygonum pensylvanicum (Pennsylvania smartweed), and Ipomoea wrightii (palmleaf morningglory). Quinclorac plus 2,4-D was the most consistent tank mixture, providing more than 80% control of all weeds at 2 and 4 WAT, except A. palmeri.     

不同除草剂对紫云英田阔叶杂草的防除效果及安全性评价

通过田间药效试验,比较了5种除草剂在紫云英田的适用性及其对阔叶杂草的防效。结果表明,紫云英田块春后化除使用56%2-甲-4-氯钠可湿性粉剂900 mL/hm~2和48%灭草松水剂2 700 m L/hm~2均未对紫云英产生药害,并可有效防除阔叶杂草,对阔叶杂草株防效及鲜重防效可达70%以上;与清水对照相比,紫云英鲜重分别提高47.92%、60.42%,紫云英结实量分别增加22.72%、31.82%。     

25种优良阔叶树种育苗技术研究

通过对吉安双江林场和南昌树木园3年生25个优良阔叶树种的育苗试验,表明采用常规育苗方法可培育出供生产用的合格苗木,但各树种在育苗时的种子催芽方法不尽相同,播种时间有所差异,同时对苗木的根系及苗木的产苗量进行了初步的探讨。     

苯磺隆与使它隆混合防治小麦田阔叶杂草的研究

[目的]确定苯磺隆与使它隆混合施用防治小麦田阔叶杂草的最佳施药方案。[方法]设置5组施药处理方案,进行施药处理,并计算株防效与鲜重防效。[结果]20%使它隆乳油30 ml/hm2+10%苯磺隆可湿粉剂20 g/hm2处理组的株防效与鲜重防效较高,分别达97.71%和98.62%。[结论]20%使它隆乳油30 ml/hm2+10%苯磺隆可湿粉剂20 g/hm2处理组,为小麦田阔叶杂草的最佳除草方案。