直播稻田杂草发生特点及其控制技术

直播稻作为一项省工节本、增产增收 ,具有显著经济效益的轻型栽培技术 ,越来越受农民的欢迎 ,种植面积不断扩大 ,由于直播稻与杂草同步生长 ,水稻前期干湿栽培 ,十分有利于老草复活和新草的萌发生长 ,稻田杂草危害已成为阻碍直播稻优质高产和大面积推广应用的主要因素。为此作者对直播稻田杂草发生特点和控制技术进行了研究 ,总结出了直播稻田除草配套技术 ,并进行了大面积推广应用 ,取得了显著的灭草增产效果。１直播稻田杂草发生特点１．１杂草发生时间长 ,具有两个明显萌发高峰。第１峰为主峰 ,在播后１０～２０ｄ出现 ,第２峰为播后２５…     

江苏省直播稻田杂草的发生规律与综合防除技术研究

江苏省水稻直播田杂草约有22科35属41种和1变种,稗草等15种为优势种群,杂草群落中各种群的组成及其比率随地区、时间及耕作栽培制度的变化而变化。杂草于水稻播种后3~4 d开始出土,第10~20 d达到出土高峰,第25~40 d又出现一个较小的出草高峰。禾本科杂草出土较早,莎草和部分阔叶草出土最迟。直播稻田杂草的综合防除要贯彻“化学防治为主,农业措施为辅”的原则,化除的关键是“一除二封三杀四补”。新野(丁.恶)、扫特、速除(异丙.丁.苄)、杀草丹、千金、二氯.苄对直播稻田杂草具有较好的防除效果。     

速除防除直播稻田杂草的效果

和移栽稻相比,直播稻田杂草发生种类更多、数量更大。2002~2004年小区试验和示范结果表明,50%速除(异丙.丁.苄)WP可有效地防除直播稻田多种一年生禾本科、阔叶类和莎草科杂草,包括千金子、稗草、鳢肠、陌上菜、异型莎草等。使用方法,水直播田用商品量60g/667m2,播后3~6d喷雾;麦套稻田水稻播后上“跑马水,”1~6d内,用商品量100~110g/667m2药土法施药。田间湿度或上水时间是影响药剂持效期和对水稻安全性的重要因子。     

直播稻田杂草萌发规律的调查

经定点调查表明，在浙江宁海直播稻田杂草萌发有３个高峰。第１峰在播后１０～２０ｄ，以禾本科、莎草科杂草为主；第２峰播后３０～５０ｄ，以阔叶杂草为主；第３峰播后６０～７５ｄ，以藻类为主。第１、２峰对水稻生长影响较大，必须尽早开展综合治理控制草害     

水直播稻田杂草发生特点与防除

江苏常州市武进区直播稻田杂草发生早，有明显的2个出草高峰。杂草发生量大，危害严重，产量损失有时可达80％以上。播后苗前施用扫茀特、直播宁等土壤处理剂是推迟出草时间，减少发生数量，控制杂草危害的有效措施。     

直播稻田杂草消长及其对产量损失研究

水稻播种后3～7天,直播稻田杂草开始陆续发生,播后10～20天为第一次发生高峰期,播后35天左右又出现第二次杂草发生高峰。免耕(一年)稻田杂草发生量高于耕翻田块,一免耕直播稻田杂草比耕翻田多2倍左右,造成水稻分蘖减少,成穗率降低,产量损失严重。尤其是稗草影响更大,经水稻抽穗期测定,水稻产量损失与稗草密度、分蘖数密切相关。直播齐穗期的严重损失预测式为:Y=470.0716-13.1377X_1-2.1092X_2,该方程式经田间小区验证,误差率为10％左右(Y<500千克0≤X≤50)。     

旱(直)播水管稻田杂草化学防除配套技术研究

水稻的直播是一项省工、省本、省力、经济效益高的栽培技术。但直播稻田的草害严重地阻碍了直播稻的发展。直播稻田因草害一般减产30％左右,严重的田块减产50％以上,甚至颗粒无收。为了解决直播稻生产中的草害问题,我们在省农科院植保所稻田草害组的主持下,从1985年开始进行了旱播水管直播稻田杂草化学防除体系的研究。现将三年中所取得的主要结果报告如下: 试验方法 (一)旱播水管直播稻田杂草发生消长规律调查旱播水管直播稻田播种后定6点,每点1平方尺。在整个生育期内,每3天调查1次,     

水直播稻田杂草竞争临界期及苗后一次化除研究

对冬小麦-水稻连作制度下的水直播稻田杂草发生动态进行监测,建立水稻播后有草/无草天数与水稻产量损失率之间的函数关系,推导出杂草与水稻的竞争临界期,并探讨水直播稻田杂草苗后一次化除技术方案。结果表明,水稻产量损失率随水稻播后有草天数的增加而增大,随无草天数的增加而降低;以3%作为水稻产量损失的最大忍受限度,则四川省水直播稻田杂草与水稻的竞争临界期为播后16～55 d。水稻播后15 d喷施3%氯氟吡啶酯乳油22.5 g a.i./hm²+300 g/L丙草胺乳油450 g a.i./hm²,播后20 d喷施20%二氯喹啉草酮可分散油悬浮剂600 g a.i./hm²+75%氯吡嘧磺隆水分散粒剂33.75 g a.i./hm²+100 g/L氰氟草酯乳油150 g a.i./hm²,或11%■唑酰草胺·五氟磺草胺可分散油悬浮剂123.75 g a.i./hm²对水直播稻田总杂草的鲜重防效均在98%以上,且对水稻安全。     

直播稻田杂草的生态特点和控制技术研究

近年来,随着直播稻种植面积不断扩大和栽培技术不断改革,田间草相也随生态条件的不同而发生了变化。水稻前期干、湿栽培,十分有利老草复活和新草的萌发生长。直播稻田杂草危害已成为阻碍直播稻优质高产和大面积推广应用的主要障碍。为了明确直播稻田杂草的生态特点和杂草萌发规律,科学制定防除策略,积极探索直播稻田杂草的化除技术,安全、有效、经济地将杂草危害损失控制在最低限度,我们于2003年开展了直播稻田杂草的生态特点和防除技术研究,初步摸清直播稻田出草规律,得出化除配套技术,并进行了大面积推广应用,取得了显著的灭草、增产效果…     

直播稻田杂草发生规律及防除方法

直播稻作为一项省力、节本、稳产栽培技术，近年来的种植面积不断扩大。由于直播稻苗与草同步生长，水稻前期的干湿栽培，十分有利于老草复活和新草发生，草害成为阻碍直播稻优质高产和进一步发展的主要原因。了解直播稻田杂草发生特点，有针对性地提出直播稻田杂草综合防治策略是十分重要的。     

Systems of designation of pathotypes of plant pathogens12

A variety of systems of designation has evolved to name pathotypes of plant pathogens. The systems were evaluated to determine those best suited for particular purposes. Virulence and avirulence/virulence formulae of pathotypes have advantage over the use of consecutive numbers or letters given in chronological order of pathotype discovery. As soon as pathotype information exceeds a certain level of complexity, mathematical codes are most advantageous, in particular two codes, octal notation and coded triplets. A more universal adoption of the most appropriate codes is recommended to ease communication and comparisons of results.     

Investigation of the Mode of Action of Nematode Neuropeptides

The neuropeptide AF2 has a complex set of actions on the dorsal muscle strip of Ascaris suum, including a potentiation of the acetylcholine-stimulated muscle contraction. Caffeine at 100 μm and 5 mm inhibited this potentiation, as did 100 μm theophylline in two out of six studies. The cyclic-AMP-potentiating compounds IBMX, dibutyryl cAMP and forskolin had no effect on the AF2-induced potentiation of the acetylcholine-stimulated muscle contraction. These preliminary data suggest that the potentiating action of AF2 is not mediated by a cAMP pathway.     

Localization of metabolic sites of action of herbicides

Time- and concentration-course studies were conducted to determine the effect of thirteen herbicides on photosynthesis, respiration, RNA synthesis, protein synthesis, and lipid synthesis using isolated single leaf cells. Each herbicide was from a different chemical class. Appropriate ¹⁴C-substrates and product purification procedures were used for each process prior to liquid scintillation counting. The most sensitive metabolic site of inhibition was photosynthesis for atrazine, bromacil, dichlobenil, monuron, and paraquat; RNA synthesis for dalapon and dinoseb; protein synthesis for chlorpropham; and lipid synthesis for CDAA, chloramben, 2,4-D, EPTC, and trifluralin. However, with several herbicides, one or more process was almost as sensitive as the one mentioned above. All herbicides inhibited more than one process, and the most sensitive site of inhibition may not be the same process that was inhibited the greatest at the maximum concentration and maximum exposure time used. Therefore, a concept of metabolic sites of action, rather than a primary site of action, appears to be more meaningful for herbicides.     

福寿螺配偶个体大小选择性初步观察

通过野外观察与实验研究,掌握了福寿螺的婚配体制及其配偶选择性规律。福寿螺与多数低等动物一样,其婚配属于乱交制,无固定配偶;雌螺对与其交配的雄螺个体大小没有选择性,而雄螺对雌螺的个体大小有选择性,倾向于与较大个的雌螺交配。     

厚朴病虫害种类的初步调查

采用标准地法和线路调查法,对湖北恩施市新塘乡双河厚朴基地的厚朴病虫害进行了系统调查,记录主要虫害13种,其中叶部害虫9种,枝干害虫2种,根部害虫2种。厚朴主要病害5种。藤壶蚧、厚朴枝角叶蜂和厚朴新丽斑蚜为湖北省首次报道,小绿叶蝉为厚朴新寄主记录种。同时记录了藤壶蚧的天敌6种,其中寄生小蜂2种,瓢虫4种;厚朴新丽斑蚜的天敌昆虫8种。对藤壶蚧、厚朴枝角叶蜂和厚朴苗木根腐病等重要病虫害的发生规律进行了初步调查,同时提出了防治建议。     

Effects of timing and method of application of Penicillium oxalicum on efficacy and duration of control of Fusarium wilt of tomato

The effects of timing and method of application of Penicillium oxalicum on the control of fusarium wilt of tomato were investigated. Application of P. oxalicum to tomato seedlings in seedbeds reduced disease caused by Fusarium oxysporum f.sp. lycopersici in a growth chamber by 45–49% and in glasshouse experiments by 22–69%. Disease suppression was maintained for 60–100 days after inoculation with the pathogen in the glasshouse. No disease reduction was observed in tomato plants where P. oxalicum was applied to seeds. Treatment with P. oxalicum did not affect the population of F. oxysporum f.sp. lycopersici in the rhizosphere.     

百合地下害虫主要种类调查及生物（源）农药筛选

调查了甘肃省临洮县为害百合的地下害虫种类, 并以主要发生为害种类为供试对象, 采用拌土法测定了几种生物（源）农药对主要害虫的室内毒力和致死中时。调查发现小云斑鳃金龟Polyphylla gracilicornis、棕色鳃金龟Holotrichia titanis为主要发生及为害种类, 不同时间发生种类存在差异, 9月份以小云斑鳃金龟幼虫发生为害为主, 发生量占地下害虫总数的66.16%, 平均种群密度为10.48头/m2, 10月份, 则以棕色鳃金龟幼虫发生为主, 发生量占地下害虫总数的96.86%, 平均种群密度为7.79头/m2, 主要取食百合根系和鳞茎, 造成根系数量减少, 鳞茎出现不规则褐色缺口或凹陷斑。药剂筛选结果表明, 1.8%阿维菌素乳油、200亿孢子/g球孢白僵菌粉剂对两种蛴螬均具有较高的杀虫活性和速效性, 药后7 d时, 校正死亡率在82.22%以上, 对小云斑鳃金龟幼虫和棕色鳃金龟幼虫的LC50分别为0.161、0.060 mg/g和5.558×107、0.362×107孢子/g, LT50分别为2.237 d（2.2 mg/g）、1.393 d（2.2 mg/g）和6.645 d（40.0×107孢子/g）、4.940 d（2.0×107孢子/g）, 这两种生物（源）农药对两种蛴螬的LC50和LT50值均略大于两种化学农药25%二嗪磷乳油、40%辛硫磷乳油处理的, 且对小云斑鳃金龟幼虫的杀虫活性均低于对棕色鳃金龟幼虫的杀虫活性, 致死中时则长于对棕色鳃金龟幼虫的致死中时。     

青稞种子带菌检测及杀菌剂消毒处理效果

为了研究青稞种子外部和内部携带真菌情况,比较不同杀菌剂对青稞种子的带菌消毒效果和对幼苗生长的影响,为青稞种子播前包衣处理和种传真菌病害防控提供依据,采用离体平皿法对云南迪庆‘云青1号’、‘云青2号’和‘短白青稞’3个主栽品种进行带菌检测,并对种子进行拌种或浸种处理测定6种杀菌剂对种子消毒效果,分析杀菌剂对种子发芽和幼苗生长的影响。结果表明:供试青稞种子表面携带的优势菌群为青霉(Penicilliumspp.)、镰刀菌(Fusariumspp.);种子内部寄藏的真菌主要为镰刀菌、核腔菌(Pyrenophoraspp.)、附球菌(Epicoccumspp.)、丝核菌(Rhizoctoniaspp.)、链格孢(Alternariaspp.)和木霉(Trichoderma spp.)。青稞不同品种的种子表面及内部携带的真菌种类差异较大。致病性测定表明,镰刀菌对种子萌发和幼苗生长影响最大,后期出现幼苗坏死现象。45%咪鲜胺EW、75%百菌清WP、50%福美双WP对青稞种子携带真菌均有显著抑制作用和消毒效果,50%福美双WP消毒效果最优,达100%;45%咪鲜胺EW、75%百菌清WP、50%福美双WP处理对青稞种子发芽和幼苗生长均无显著影响。     

Mode of action of meturine

The effect of meturine on the light processes of photosynthesis was studied.Meturine is a herbicide for weed control in potato and cotton crops. It is a N-phenyl—N-hydroxy—N′-methylurea.The experiments were carried out on isolated pea and spinach chloroplasts.When examining photosystem I, reduced DPIP was used as an electron donor, whereas methyl-viologen served as an electron acceptor. When examining photosystem II, DPIP represented the electron acceptor.The obtained experimental results have pointed to the absence of the effect of meturine upon the photoreaction I.Unlike N-phenyl—N′, N′-dimethylureas (CMU, DCMU) meturine has been a very weak inhibitor of photoreaction II.The authors explain the photoreaction II inhibition of chloroplasts from plants treated with herbicidal doses of meturine by conversion of N-phenyl—N-hydroxy—N′-methylurea into Hill reaction inhibitor(s). N-Phenyl—N′-methylurea can be one of such meturine metabolites.Meturine herbicidal action is accounted for by meturine transformation into Hill reaction inhibitor(s) in the plant tissues.