Effect of initial herbicide treatment and planting material on woody weed development and the growth of Eucalyptus nitens and Eucalyptus regnans

A research study of establishment techniques in plantations of Eucalyptus nitens (Deane et Maiden) Maiden and Eucalyptus regnans F Mueller was assessed for growth at age 12 years. Biomass of trees and woody weeds was determined in the 13th year to evaluate the long-term effect of herbicide treatment on plots established with optimum seedling tree and site preparation. Eucalyptus regnans produced only 60% of the biomass of E. nitens. Under-storey woody weed biomass under E. regnans comprised 18–30% of the total biomass compared with 6% for E. nitens plots. There was less total under-storey weed biomass under the herbicide-treated plots, but a similar weed leaf biomass. Under-storey weed leaf biomass contributed 14–40% of the total leaf biomass on the plots. Despite under-storey weed biomass being substantially greater on the no-herbicide plots sampled, this competition had not generally reduced growth of the trees compared with the herbicide-treated plots. Suitable site preparation, providing weed-free conditions at the time of planting, resulted in woody weed control adequate to establish seedlings and allow full growth without the use of herbicides, given suitable seedling material. Although pre-planting herbicide treatment was not necessary for optimum growth of E. nitens grown from bare-root transplants, it did improve growth of slower-growing planting stock.     

Metabolism and selectivity of rice herbicides in plants

Chemical weed control with effective and highly active herbicides has been very useful and convenient means. It has contributed to stable crop production and is labor saving. Recent herbicides have had characteristics such as high effectiveness without causing environmental pollution or harmful effects, and appropriate herbicides having high activity, low toxicity, high selectivity and being non-persistent have been developed. The metabolism of rice herbicides used mainly in Japan, such as sulfonylurea, chloroacetamide, acylamide, urea, thiocarbamate, pyrazole, triazine, diphenyl ether, phthalimide, phenoxy, aryloxyphenoxypropionate, etc., is reviewed, and its involvement in selectivity is also discussed. The metabolism of herbicides is closely related to their activity and selectivity. Differential herbicide metabolism in plants is a contributing factor of selectivity between crops and weeds. Chemicals that are more detoxified in crops and/or more activated or less detoxified in weeds are considered as being effective and selective herbicides. The metabolism of various types of rice herbicides includes: oxidative reaction (ring and chain hydroxylation, O - and N -dealkylation), hydrolysis and subsequent glucose conjugation, and glutathione conjugation in rice. These detoxicative activities are much higher in rice than weeds in paddies, and this leads to the selectivity of herbicides. Enzymes, oxidase, P-450 mono-oxygenase, esterase, acylamidase, glucosyl transferase, glutathione transferase, etc., play important roles in herbicide metabolism and selectivity.     

河北省夏播玉米田杂草的发生及化学防除

本文论述了河北省夏播玉米田杂草群落的组成、翻耕和免耕两种不同种植方式的玉米田杂草的发生及消长规律 ,并就不同种植方式的玉米田提出了相应的化学防除药剂及施用技术 :在翻耕玉米田 ,以喷施乙阿合剂做播后苗前土壤处理为主 ;免耕贴茬玉米田 ,在作物播后苗前喷施农达混用乙阿合剂 ;麦垅套种的玉米田 ,在小麦收获后立即喷施玉农乐或玉农乐与阿特拉津混用做茎叶处理 ;采用克芜踪行间定向喷雾防除玉米生育后期的杂草     

山岗瘠薄地苹果增产措施探索

为探索山丘薄地苹果树的有效增产措施,1989～1993年在新密市牛店乡的花家店小流域建立了3hm~2苹果丰产试验园.经5年试验,初步探索出了一套切实可行的增产措施,明显提高了果品产量及质量,与对照区相比,1994年、1995年、1996年苹果增产幅度分别为150%、220%及212%.其主要增产措施是:以保水增肥为中心,利用秸秆、杂草进行果园常年覆盖或春夏覆盖秋后掩埋覆草,并结合山地果树生长特点进行科学修剪.     

基于多光谱融合图像的背景分割

针对可见光或近红外图像背景分割存在精度不高的问题,提出多光谱融合的图像分割。首先采集红色、绿色和近红外3个波段光谱图像,采用r ir、2g-r-ir、R G IR、g ir、g r、ir-r、IR-R等融合方式,然后使用最大方差自动取阈值法确定阈值,并根据此阈值分割图像。在试验中,进行了各种融合图像分割效果的对比研究,并与原始的单波段光谱图像进行比较研究。试验结果表明,IR-R的融合方式效果最好。     

广州市草坪杂草发生情况新报及防除措施研究

通过一年4次在不同区域的调查,发现广州地区草坪杂草有145种,122属,50科,严重为害的有虾钳菜Alternanthera sessilis,空心莲子草A.philoxeroides,红花酢浆草Oxalis corymbosa:,酢浆草O.corniculata,积雪草Centella asiatica,天胡荽Hydrocotyle sibthorpioides,鳢肠Ecliptaprostrata,泥花草Lindernia antipoda,莎草Cyperus rotundus,水蜈蚣Kyllinga brevifolia,绊根草Cynodondactylon,马唐Digitaria sanguinalis等10余种.与1 995年调查结果比较,杂草种类增多,严重为害的杂草种类有较大变化,针对杂草的演变进行了防除措施的分析.     

Effect of tillage systems on pea crop infestation with weeds

In a multi-year experiment, weed infestation of pea crop in three tillage systems was analyzed: a) conventional tillage (CT), b) reduced tillage (RT), and c) no-tillage (NT), and in two terms: 1) at 2–3 pea leaves stage (23–25 stage in BBCH scale) and 2) at the flat pod stage (75–79 BBCH). Treatments conducted in the CT system included shallow ploughing and pre-winter ploughing in the autumn. In the RT system, both these treatments were replaced by double cultivation, whereas only glyphosate treatment was applied in the NT system. In both terms of weed infestation assessment, the highest number and air-dry weight of weeds were determined in the RT system, lower ones in CT and the lowest ones in the NT system. In the first term, the number of weeds m^?2 in the RT system was higher by 43.9% than in NT and by 26% than in CT system. Also in the second term was the weed number m^?2 in RT higher by 58.6% than in NT and by 27.9% than in CT. Tillage systems differentiated also weed mass in pea crop. In RT, it was 4-fold higher than in NT and over 2-fold higher than in CT.     

Weed growth,herbicide efficacy,and rice productivity in dry seeded paddy field under different wheat stubble management methods

To ascertain the influence of wheat stubble management options and chemical weed control methods on weed growth and productivity of dry direct-seeded fine rice, a two years' field study was undertaken at the Agronomic Research Farm, University of Agriculture, Faisalabad, Pakistan in 2013 and 2014. Different wheat stubble management methods, viz., incorporation, burning and retention were executed during seed-bed preparation. While, herbicide treatments comprised of a weed check, weed free, pendimethalin followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl, and bispyribac sodium followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl. Results revealed that weed control efficacy of both herbicide treatments ranged from 84 to 94%. Herbicide treatments significantly reduced weed density(88–90%) and dry weight(86–88%), while improved the rice growth attributes compared with weed check. Application of bispyribac sodium followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl in stubble retention recorded 226 and 273% increase in kernel yield over weedy check in 2013 and 2014, respectively. In stubble incorporation, pendimethalin followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl was more effective in increasing(256–293%) rice yields over weedy check. Among different treatment combinations, the maximum net benefits(1 397.49~(–1) 472.22 USD ha~(–1)), net returns(636–700 USD ha~(–1)), benefit cost ratio(1.77~(–1).83) and marginal rate of return(2 187–2 330%) were recorded with the application of bispyribac sodium followed by fenoxaprop p-ethyl+ethoxysulfuron ethyl in stubble retention. In crux, application of bispyribac sodium followed by tank mixture of fenoxaprop p-ethyl+ethoxysulfuron ethyl in stubble retention is efficient approach to control weeds, and get maximum rice productivity and net economic returns under dry seeded system.     

河北省邯郸市麦田禾本科杂草发生情况调查

采用随机取点和倒置“W”取样相结合的方法,对河北省邯郸市麦田禾本科杂草的发生情况进行了调查。结果表明：邯郸市麦田禾本科杂草主要为节节麦、日本看麦娘和野燕麦。不同调查县份的禾本科杂草优势种类差异很大。永年县麦田禾本科杂草主要为日本看麦娘和节节麦,相对多度分别为41.7％和40.6％;磁县麦田禾本科杂草主要为节节麦、日本看麦娘和野燕麦,相对多度分别为28.4％、4.0％和1.9％;肥乡县和曲周县麦田禾本科杂草主要为节节麦,相对多度分别为5.1％和9.4％。     

膜下滴灌棉田杂草群落组成及特点的初步研究——以阿瓦提县为例

[目的]摸清滴灌模式下棉田杂草群落种类、数量,为南疆早中熟塔哈次棉花亚区滴灌棉田杂草的科学防治提供理论依据.[方法]以阿瓦提县具有多年膜下滴灌种植条件的乡(场)为重点,调查研究杂草群落种类及数量,并与该县不同植棉模式下棉田杂草群落进行比较.[结果]不同植棉模式下杂草种类均较多,滴灌棉田杂草主要有9科15种,以禾本科、菊科、藜科对棉花生长影响较大.[结论]通过与露地直播、常规灌棉田杂草比较,膜下滴灌棉田杂草根的干重明显较低,一年生浅根杂草及阔叶杂草呈增多趋势.杂草在棉花生育期有两个危害高峰,且危害高峰提前并持续时间较长.