淮北地区直播稻田杂草稻的特征特性及防除技术

水稻直播栽培具有省水、省田、省工、节本的优点，加之直播稻可推迟水稻播期以避开灰飞虱的迁移高峰，减轻灰飞虱危害，从而控制条纹叶枯病的发生，故深受广大稻农喜爱，被稻农自发使用。近年来，江苏省直播稻面积扩展迅速，2005年仅为25．3万hm^2，     

水稻灰飞虱转移穗部为害及其对产量损失的观察

近年来,水稻灰飞虱在太仓市严重发生,不仅传播条纹叶枯病,引起减产,还在穗部直接吸汁为害影响产量和品质。据测定,灰飞虱吸汁为害可造成千粒重下降6.8%～23.9%,对直播稻的为害比移栽稻更重。灰飞虱转移穗部为害源自成虫产卵部位向穗部转移,4代成虫在穗轴、穗颈上的产卵量占全株产卵量的79.0%～83.6%。     

水稻品种对灰飞虱的抗性及其机制

为明确水稻品种对灰飞虱的抗性及其机制,研究了11个水稻品种对灰飞虱的忌避性和抗生性,并进一步分析了营养物质、二氧化硅(SiO2)以及草酸含量与抗虫性的关系。结果表明,武粳15、武运粳7号及武运粳8号等3个粳稻品种感灰飞虱;镇稻2号、徐稻3号、盐稻8号、扬粳9538等4个粳稻品种以及汕优63、协优63、协优136、丰优香占等4个杂交组合中抗或高抗灰飞虱。灰飞虱若虫存活率与水稻植株体内可溶性糖含量、淀粉含量、游离氨基酸总量以及可溶性蛋白质含量均呈极显著的正相关。镇稻2号、徐稻3号、协优136叶鞘中SiO2含量分别为0.1660±0.0027、0.1530±0.0081、0.1401±0.0064g/g,显著地高于感虫对照。扬粳9538、镇稻2号叶片草酸含量分别为56.372±1.086、53.763±1.887μg/mL,显著高于感虫对照。低含量营养物质使供试水稻品种对灰飞虱表现抗性,SiO2含量和草酸含量较高是部分水稻品种(如镇稻2号)抗虫的原因。     

农业栽培措施防治水稻前期条纹叶枯病效果

常州地区2004年灰飞虱特大发生,其主害代(第1代)的虫量是常年同期虫量的30倍左右。由于1代灰飞虱成虫发生早,向秧田迁移早,高峰期长,单靠秧田期喷药防治灰飞虱已不能控制水稻前期条纹叶病的为害。增加用药次数和用药量虽可使治虫、防病效果提高,但是由此带来的负作用也很大。为此,笔者通过试验示范,指出应用水稻机插栽培技术和推迟播栽期等农业措施,是控制水稻前期条纹叶枯病的有效措施,且具有成本低,无污染等优点。1试验方法1.1水稻不同栽培方式的条纹叶枯病比较设3组示范试验:①机插稻和直播稻示范。示范区设置在前黄镇南降丰产方。播种期…     

灰飞虱致灾特点及防治对策

随着种植结构的调整,传毒昆虫灰飞虱在东台市稻区迅速上升为优势种群,近几年由于受上年五代灰飞虱虫源基数大、冬春气温偏高、小麦收获时间推迟以及种植方式多样化等因素的影响,东台市稻田一代和二代灰飞虱连续大发生,十分有利于水稻条纹叶枯病病毒的传播蔓延,已成为水稻生产上最主要的害虫之一,给水稻病虫防治带来了新的课题。     

东海县2005年灰飞虱越冬数量创历史新高

灰飞虱在东海县能够安全越冬,越冬数量直接影响翌年灰飞虱发生程度。2005年是灰飞虱在本县越冬数量是有记载以来最高年份。灰飞虱在本县连续3年大发生至特大发生,水稻条纹叶枯病及玉米粗缩病近2年均表现为大发生,经省农科院专家鉴定,本县小麦个别品种(如烟农19)出现零星小麦条纹叶枯病病株,因此形势越来越严峻。东海县植保植检站于2005年11月15日对全县6.7万hm2小麦田灰飞虱进行普查,全县加权平均14167.2头/667m2,比2004年大发生年份多10565.4头/667m2。其中稻套麦田灰飞虱数量高达32890头/667m2,其主要原因是稻套麦田中高留稻桩为灰飞虱安…     

两种稻虱缨小蜂对稻飞虱的控制作用

稻虱缨小蜂和拟稻虱缨小蜂是稻飞虱卵期重要的寄生性天敌。南京江浦稻田8月上旬前以稻虱缨小蜂为主,主要寄生于灰飞虱和白背飞虱卵,8月中旬以后则以拟稻虱缨小蜂占优势,主要寄生于褐飞虱卵。水稻苗期灰飞虱卵寄生率平均为27.3％,白背飞虱和褐飞虱卵寄生率,杂交稻田为10.87％和21.5％,晚粳稻田为20.67％和19.6％。白背飞虱寄生卵量与总卵量间里直线相关,而褐飞虱寄生卵量与总卵量间呈幂回归关系,回归方程分别为Y=-18.2128+0.2075x和Y=0.006807x~(1·4887)     

我国水稻五大产区虫害发生及防控情况差异的比较分析

为掌握我国水稻各产区害虫的发生形势和防控现状,为分区域治理提供科学依据,本文分析了11年来水稻五大产区(华中稻区、西南稻区、华南稻区、东北稻区和华北稻区)的二化螟、三化螟、稻纵卷叶螟、褐飞虱、白背飞虱和灰飞虱的发生及防控情况,并进行了差异比较分析。结果显示：二化螟、稻纵卷叶螟、褐飞虱和白背飞虱是我国水稻的主要害虫。五大产区的害虫发生情况不同,二化螟在东北稻区、西南稻区和华北稻区整体发生较重;“两迁”害虫(稻纵卷叶螟和稻飞虱)在华中稻区、华南稻区和西南稻区发生较重。水稻病虫害防控主要通过化学防治,应进一步提升物理防治和生物防治比重,推进水稻绿色防控技术的普及应用。     

水稻的主要养分组成和显微结构对灰飞虱取食选择性的影响

通过测定灰飞虱在12个不同类型水稻品种上的取食选择性和稻株的含水量、可溶性糖含量、蛋白质含量及粗纤维含量,激光共聚焦显微镜观察稻叶片和茎杆的结构及硅化细胞分布,从养分组成和显微结构两个方面研究灰飞虱对寄主的选择性及其影响因子.结果表明:在植株的养分组成中,对灰飞虱取食选择性起决定性作用的是粗纤维含量,它与虫口密度显著负相关,相关系数达-0.96;而蛋白质含量和含水量均与虫口密度显著正相关,相关系数分别为0.79和0.89,植株可溶性糖含量对灰飞虱取食选择性影响不显著.在显微结构方面,植株硅化细胞体积和密度大、叶脉间距小、叶脉宽的水稻品种对灰飞虱的非选择性强.     

麦田越冬灰飞虱药剂防治试验

灰飞虱[Laodepjax striatellus(Fallén)]是传播小麦丛矮病、水稻条纹叶枯病、水稻黑条矮缩病、玉米粗缩病的罪魁祸首,近几年来,给农业生产带来很大的损失.江苏省苏北地区常规防治灰飞虱的时间主要在5月底6月初,以防治向水稻秧田转移的1代灰飞虱成虫和2代灰飞虱的若虫为主,很少见到对麦田越冬灰飞虱防治的报道.为此,笔者于2008年进行了麦田越冬灰飞虱的药剂防治试验.     

Control of wild rice in rice

The four main wild rice species are: Oryza rufipogon Griff, embracing a wide range of “red rice” types closely related to O. sativa L.; O. longistaminata Chev. & Roehr, a rhizomatous perennial; O. barthii Chev. the annual wild rice of West Africa; and O. punctata Kotschy ex Steud, a small seeded annual. The distribution and importance of these species are discussed in relation to the different systems of rice growing. Annual wild rice problems are favoured by dry sowing followed by flooding. For cultural control, soil puddling and direct sowing into water are recommended. In a series of pot experiments with O. punctata and rice, 18 herbicides were shown to be at least partially selective, including: alachlor, butachlor, S-4-chlorobenzyl diethyldithiocarbamate (B-3015), 4-(2,6-dichlorobenzyloxymethyl)-4-ethyl-2,2-dimethyl-1,3-dioxolan (WL 29226), 3-(α α-dimethylbenzyl)-1-methyl-1-phenylurea (K 1441), isoproturon, metamitron, molinate and perfluidone. B-3015 was the most selective of these but the selectivity of alachlor and molinate could be greatly increased and became comparable to B-3015 when the crop seed was dressed with the protectant 1,8-naphthalic anhydride (NA). Other herbicides for which NA provided a protective effect were: butachlor, metolachlor (CGA 24705), epronaz, ethofumesate, perfluidone and 4,4,4-trichloro-2-phenylbut-1-ene (Dowco 221).     

水稻条纹叶枯病个体茎、蘖显症特点

2003～2004年定点调查表明,水稻条纹叶枯病在秧苗期主茎显症后,同株的分蘖全部显症,病株死亡。分蘖期主茎显症后,同株的分蘖全部显症;部分分蘖显症后,同株的主茎和其余分蘖全部显症,病株死亡或不成穗。拔节期主茎显症后,同株的大部分分蘖(68.9%～79.2%)显症,部分茎、蘖(32.9%～23.0%)成穗,产量损失较大(80.8%);部分分蘖显症后,同株的主茎不显症,其余分蘖部分显症(分蘖总显症率为53.0%～66.7%),全部主茎和部分分蘖成穗(总成穗率61.1%～48.1%),产量损失较小(34.5%)。病株不侵染同穴健株。由此提出治虫防病、改茬和病后处理方法。     

Transgenic rice plants that over-express the mannose-binding rice lectin have enhanced resistance to rice blast

Mannose-binding rice lectin (MRL), which is almost identical to the salt-induced protein SalT, binds to mannose and glucose residues. Expression of the MRL gene in response to infection with Magnaporthe oryzae, the rice blast fungus, was stronger in the incompatible interaction than in the compatible. Transgenic rice plants that constitutively over-expressed MRL strongly suppressed the growth of invasive hyphae of the fungus on leaf sheaths and the development of typical susceptible-type lesions on leaf blades, but did not affect penetration by the fungus in comparison with the wild-type. On a polycarbonate plate, purified recombinant MRL inhibited conidial attachment and appressorium formation but not conidial germination. These results suggest that MRL may play an essential role in disease resistance by suppressing development of M. oryzae in situ.     

稻田杂草稻发生趋重水稻生产受到威胁

杂草稻,一般认为是栽培稻和野生稻的天然杂交种,但目前尚未肯定杂草稻的真正起源.杂草稻以易落粒、能休眠以及与栽培稻的竞争性等特征使其成为一种杂草.杂草稻在大部分种植水稻地区均能生长.在泰国、越南、马来西亚等水稻生产国发生危害较重.近年来,在我国的江苏、湖南、广东、辽宁、上海等省(直辖市)的一些稻区发生越来越重,严重影响水稻的产量和品质.     

杂交稻对稻瘟病和稻白叶枯病的抗性鉴定

对广东省将推广的54份杂交稻组合对稻瘟病和白叶枯病的抗病性进行了鉴定。对稻瘟病的抗病性鉴定表明:抗病组合共49个,占90.7%;其中,高抗(抗性比≥91%)组合30个,占55.6%。对稻白叶枯病的抗病性鉴定表明:没有高抗(HR)和抗(R)的组合,仅有一个杂交稻组合(西胜2175)表现为中抗(mR),仅占1.9%,其余53个组合都表现感病,占98.1%。进一步分析表明:对稻瘟病表现高抗的30个杂交稻组合都不抗白叶枯病,而中抗白叶枯病的杂交稻组合西胜2175对稻瘟病表现为中抗,抗性比为74%。     

自生稻对栽培稻的危害及控制措施

自生稻在江苏许多市县都有发生,给水稻生产造成一定损失.通过对自生稻危害性的探讨,为控制自生稻的蔓延、危害创造了条件,并初步探讨了控制自生稻蔓延、危害的措施.     

丙草胺防治直播稻田杂草稻的技术研究

为了探寻对栽培稻安全的杂草稻防除技术,采用整株测定法研究了丙草胺对杂草稻的毒力及解草啶减轻丙草胺对栽培稻药害的应用技术,并通过田间试验检验了这一技术的安全性。结果表明:丙草胺在450g/hm2时,可显著抑制杂草稻和栽培稻的生长;采用30mg/L解草啶浸种48h,可显著减轻丙草胺对栽培稻的药害,随着丙草胺施药量的增加,解草啶的保护作用逐渐减弱。田间试验结果说明:用30mg/L解草啶浸种栽培稻48h,丙草胺的施药剂量在450~675g/hm2时对栽培稻安全;当丙草胺剂量为900g/hm2时,栽培稻产量显著下降。     

烯啶虫胺在水稻和稻田环境中的残留及消解动态

采用高效液相色谱-紫外检测器(HPLC-UVD)测定了烯啶虫胺在稻田水、土壤、水稻植株和糙米样品中的消解动态及最终残留。田水样品用二氯甲烷萃取;土壤样品用水提取后经二氯甲烷萃取;水稻植株和糙米样品依次用水、丙酮提取,提取液经液液萃取及柱层析净化;HPLC-UVD检测。当烯啶虫胺在田水和土壤中的添加水平为0.1~5 mg/L和0.1~5 mg/kg,在植株和糙米中的添加水平为0.2~5 mg/kg时,其平均添加回收率在77.2% ~100.3%之间,相对标准偏差 (RSD)在1.9% ~12.9%之间。烯啶虫胺在稻田水、土壤、植株和糙米中方法的定量限(LOQ)分别为0.1 mg/L和0.1、0.2、0.2 mg/kg,检出限(LOD)分别为0.04 mg/L和0.04、0.08、0.08 mg/kg。温室模拟消解动态试验结果显示,以推荐使用高剂量的20倍(有效成分1 500 g/hm2) 施药,烯啶虫胺在稻田水、土壤以及水稻植株中的消解动态规律均符合一级动力学方程,其半衰期分别为0.58、3.31及2.70 d,消解速率较快。最终残留试验表明,于大田分蘖期按推荐使用高剂量的1.5倍(有效成分112.5 g/hm2)分别施药3次和4次,间隔期为7 d,距最后一次施药7 d后采样,糙米中烯啶虫胺的残留量均低于LOD值(0.08 mg/kg)及日本规定的最大残留限量(MRL)值(0.5 mg/kg)。     

Potential allelopathic rice lines for weed management in Cambodian rice production

In Cambodia, the planting of rice lines with a competitive and/or allelopathic ability would be a very useful way to supplement weed management in the rain‐fed, low‐input production systems. The present study examines a wide range of rice germplasm, mainly from Cambodia, and uses a series of bioassay techniques to identify those that might have a weed growth‐suppressing, allelopathic trait. A laboratory bioassay study that involved 359 rice lines showed that there were 15 that could significantly reduce the growth of awnless barnyard grass seedlings. In a second laboratory bioassay, involving the best 96 rice lines that were identified in the first study, 14 were shown to suppress the shoot growth of awnless barnyard grass, 11 could suppress the shoot growth of barnyard grass, six could suppress the shoot growth of small umbrella sedge, four could suppress the shoot growth of two‐leaf fimbristylis, four could suppress the shoot growth of water primrose, and three could suppress the shoot growth of gooseweed. Of the 13 rice lines that were able to suppress the growth of at least two weed species, there were three lines that could suppress the growth of three weed species, one line that could suppress the growth of four weed species, and one line that could suppress the growth of five weed species. In a third soil‐based, pot bioassay that studied the 18 best lines coming from the second laboratory bioassay, all showed a significant weed growth‐suppressive ability. A linear regression analysis showed that there was no correlation between their weed growth‐suppressive ability and their physical seedling size, supporting the idea that the growth suppression was allelopathic in nature and not a physical competition effect. In summary, the results indicate that an allelopathic trait does exist in some Cambodian rice lines and that this trait is effective in the growth suppression of a number of major rice weeds.     

Screening rice varieties for resistance to rice yellow mottle virus disease

Abstract

Rice yellow mottle virus (RYMV) is one of the major constraints to rice production in Kenya. The reactions of 30 varieties of rice to an isolate of RYMV were studied. The appearance and development of symptoms in the various varieties were scored on a 0–5 scale. The observed reactions ranged from highly susceptible to highly resistant. Thirty‐six per cent of the varieties showed a high level of resistance while 23.3% were highly susceptible. The intermediate reactions were 16.7% resistant, 6.6% susceptible and 16.7% moderately susceptible.