水葫芦的生物防治

水葫芦是全世界公认的“十大”害草之一，危害严重。用物理和化学的方法防治该草难以得到持续的效果，且易造成二次污染，而生物防治是一种持久性、成本较低、环境友好型的治理方法。本文从水葫芦天敌、水葫芦病原菌和植物的化感作用等方面阐述了生物防治的现状及存在的问题，并就其前景进行了探讨。     

水葫芦象甲对水葫芦的生物防治效应

通过在室内塑箱释放专食性天敌昆虫——水葫芦象甲以控制水葫芦的研究。初步探明了水葫芦象甲不同释放密度对水葫芦植株生长的影响、控制效果以及适宜的水葫芦象甲释放密度,为水葫芦生物防除的推广应用提供了一定的理论基础。     

利用水葫芦象甲和农达综合控制水葫芦

试验表明同时应用水葫芦象甲和农达控制水葫芦,可达到快速、持续的控制效果,但农达使用剂量应选择适当。药量４.５ｋｇ／ｈｍ^２的综防处理区中,由于农达的作用水葫芦植株在２０～５０ｄ内大部分死亡,水葫芦象甲亦很快死亡,象甲很难发挥有效的作用;药量为０.４５ｋｇ／ｈｍ^２的综防区中,水葫芦象甲和农达同时作用,对水葫芦的叶片数、繁殖量和生物量起到了明显的抑制作用,与单独施用同样药量的化防区和只释放象甲的生防区有显著差异,而且象甲保持了一定的种群密度;而药量为０.０４５ｋｇ／ｈｍ^２的综防区与只放象甲的生防区控制水葫芦的效果一样。     

水葫芦象甲对外来杂草水葫芦的控制效果

外来植物水葫芦是目前我国南方危害最为严重的水生杂草。本文研究了野外释放从国外引进的专食性天敌昆虫控制水葫芦的效果。1996年8月在浙江温州面积为1372m^2、水葫芦覆盖率达100％的河道上释放1000头象甲，放虫2年后，水葫芦植株长势明显受到抑制，但仍有75％的水面被覆盖。防效仅为25％，3年后，发展迅速，效果十分显著，99％的水葫芦被清除。随着放虫区水葫芦数量和长势的减弱，象甲开始向四周扩散，首先扩散到紧邻放虫区面积为3000m^2的河道上，并在1999年4月将70％的水葫芦清除；同年12月发现，从放虫区沿河道向下游20km，均可发现象甲。     

水葫芦的综合利用

该文简述了水葫芦的生物学特性,详细介绍了这种水生植物在造纸、肥料、饲料、食用和药用以及污水治理等方面的应用现状与前景,并提出了水葫芦利用过程中须要注意的问题。     

用不同日龄水葫芦叶片饲养对水葫芦象甲的影响

水葫芦(Eichnornia crassipes(Mart)Solms-Laub)是目前世界上危害最严重的多年生水生杂草(私人通信).近年来大面积覆盖我国南方的很多水体,带来严重的生态、经济和社会危害[1].为控制水葫芦的蔓延为害,中国农科院1995从美国和阿根廷引进了两种天敌昆虫(Neochetina eichhorniae和N.brachi),有效地抑制了已释省区水葫芦的生长[2].国外曾就水葫芦叶龄对N.eichhorniae卵和幼虫在植株体内分布的影响进行过研究[3],本文就用不同日龄水葫芦叶片饲养对象甲的影响进行了研究,为人工饲养象甲提供科学依据.     

农达对水葫芦象甲的影响

用４１％农达加水分别稀释３０、１００、３００、１０００和３０００倍,在室内测试了对水葫芦象甲的影响。结果表明,象甲卵和初孵幼虫直接接触药液对孵化率和化蛹率没有明显的影响。将药液直接喷施于成虫体表后再饲喂新鲜健康的叶片对象甲存活没有明显的影响。用不同浓度药液处理的叶片饲喂象甲成虫１月后,存活率分别为１０．０％、４５．０％、４２．５％、６６．７％和７７．５％,对照为７２．５％。室外种群动态试验发现,用１００倍以下药液处理有象甲成虫和幼虫的水葫芦小区３个月后,水葫芦和象甲全部死亡;而用３００倍以上农达处理的小区内象甲仍保持一定的种群数量。本项研究表明低浓度农达对象甲比较安全,可与象甲配合控制水葫芦。     

防除水葫芦除草剂的筛选

对8种除草剂筛选试验结果表明,克无踪对水葫芦表现速效,喷药后8 d叶枯萎率及株死亡率均达99%以上;飞达防除水葫芦的效果较缓慢,但在药后16 d叶枯萎率及株死亡率均达100%;2,4-D、草革和2甲4氯也均表现出良好的防效,防除水葫芦的效果介于克无踪和飞达之间;丁草胺和乙草胺的防除效果不明显,药后16 d叶枯萎率仅分别为9.3%和27.3%,株死亡率分别为0.3%和11.7%.     

斜纹夜蛾取食水葫芦的观察

斜纹夜蛾幼虫可大量取食水葫芦的叶与叶柄,当幼虫达到一定密度时,水葫芦的生长受到抑制,甚至造成枯萎、死亡。3只斜纹夜蛾幼虫可造成1株水葫芦死亡。斜纹夜蛾幼虫能够有效地抑制水葫芦的生长,为水葫芦的治理提供新的思路。     

水葫芦象甲的生物学及其寄主专一性

在室温 2 5～ 2 8℃的养虫室内 ,水葫芦象甲雌成虫寿命最长可达 1 6 1d ,最大卵量为 1 0 91粒。产卵期为 2 0～ 1 59d。卵主要产在叶柄内。幼虫孵化后在叶片内和叶柄中取食 ,并向植株基部钻蛀。幼虫期 30～ 4 0d。老熟幼虫在活的水葫芦植株根部化蛹 ,蛹期 2 5～ 30d。在温州自然条件下 ,象甲年发生 2代 ,并有明显的世代重叠现象。以成虫和幼虫越冬。利用 2 3科 4 6种植物进行的寄主专一性测定发现 ,该象甲只为害水葫芦 ,可安全用于水葫芦的生物防治     

两种除草剂对水葫芦和大薸的防除效果

采用枯叶指数、枯柄指数、新根抑制、鲜重防效等指标,评价480g/L灭草松水剂和10%硝磺草酮可分散油悬浮剂对水葫芦及大薸的防除效果。盆栽毒力测定结果表明,10%硝磺草酮可分散油悬浮剂对水葫芦和大薸新根有很好的抑制作用,药后10d,LC50分别为14.22和7.21mg/L;480g/L灭草松水剂对水葫芦和大薸鲜重的毒力较强,药后10d,LC50分别为548.22和3.49mg/L;药后20d,LC50分别为53.28和3.31mg/L;而2种除草剂对水葫芦叶片、叶柄和大薸的叶片毒力均较低,其中480g/L灭草松水剂对水葫芦叶片和叶柄毒力优于10%硝磺草酮可分散油悬浮剂,药后30dLC50分别为94.40和93.43mg/L;对大薸叶片毒力较强的是10%硝磺草酮可分散油悬浮剂,药后20dLC50为165.07 mg/L,在实际应用中,为提高防治效果,可适当提高剂量或进行混配处理。     

Preliminary experiments on utilization of water hyacinth by grass carp

Preliminary aquarium experiments have been carried out on the feeding of water hyacinth (Eichhornia crassipes (Mart.) Solms) to grass carp (Ctenopharyngodon idella Via.). Eleven months old fish weighing 38 to 104 g were fed for 50 days exclusively on E. crassipes. Roots and leaves were accepted readily but the swollen petioles reluctantly. The fish developed well, producing 6.5g live weight from 10g dry matter of E. crassipes. The results suggest the possible use of grass carp for the solution of E. crassipes problems. Further extensive experiments are required in the field, however, to determine the influence of grass carp on the ecology of waters infested with this weed.     

Integrated control of water hyacinth in Africa1

Water hyacinth, Eichhornia crassipes was first recorded in Africa (Egypt and South Africa) in the late 1800s. Since this time it has invaded streams, rivers, natural lakes and impoundments throughout the continent. Large mats of water hyacinth severely degrade aquatic ecosystems and limit all aspects of water resource utilization, threatening food security and economic development in a number of countries. The severity of these infestations is invariably exacerbated by eutrophication. Control options include manual removal, mechanical control, application of herbicides and biological control. Biological control offers a long‐term solution and excellent results have been achieved in a number of tropical large freshwater bodies, most notably Lake Victoria. However, in the more temperate regions of the continent and where extensive eutrophication exists, biological control is integrated with other control options. The successful control of water hyacinth relies on establishing an acceptable threshold population level for the weed, adopting a management philosophy that includes a top‐down approach within the infested catchment, intelligent use of herbicide, mechanical and biological control and a commitment to the reduction in nitrate and phosphate inputs into the aquatic ecosystem.     

植物水分利用效率及其研究进展

概述了植物水分利用效率（WUE）的研究进展，并重点就植物水分利用效率的影响因子、植物品种间WUE差异的生理生化基础及其遗传背景、植物水分利用效率研究方法的改进以及今后的研究重点进行了讨论。     

旱作农田水肥耦合研究进展

在查阅1970～2004年国内外大量旱作农田水肥耦合研究资料的基础上,重点对其中30篇进行了分析总结。综合评述了旱作农田水肥效应关系、水肥对作物生长和产量的影响、不同水肥条件对作物水分利用效率(WUE)的影响、施肥对农田生态环境的影响以及水肥耦合模型和研究方法等研究进展情况。指出今后水肥耦合研究应该加强施肥对农产品品质和生态环境的影响的研究,同时依据不同试验目的选用田间试验或模拟试验,注重构建通用性的水肥耦合模型。     

Some aspects of utilization of water hyacinth (Eichhornia crassipes)

Abstract

DISPOSAL AND DECONTAMINATION OF PESTICIDES. Edited by Maurice V. Kennedy. ACS Symposium Series No. 73. American Chemical Society, Washington D.C., 1978. ISBN 0 8412 0443 0. Pp. 158. Price US $20.00.

MICRO-ORGANISMS ASSOCIATED WITH RUBBER (HEVEA BRASILIENSIS MUELL. ARG.). K. H. Chee. Agricultural Series Report No. 4, Rubber Research Institute of Malaysia. Kuala Lumpur, 1976. Pp. 78. Price M$15.00

PEST CONTROL STRATEGIES. Edited by E. H. Smith and D. Pimentel. Academic Press, New York, San Francisco and London, 1978. ISBN 0 12 650450 4. Pp. 334. Price £10.40, US $16.00.

SORGHUM AND PEARL MILLET DISEASE IDENTIFICATION HANDBOOK. R. J. Williams, R. A. Frederiksen and J. C. Girard. International Crops Research Institute for the Semi-Arid Tropics, Hyderabad, India, 1978. Information Bulletin No. 2. Pp. 88. Free.

PESTICIDE RESIDUES. A REVIEW OF INDIAN WORK. V. Agnihothrudu and M. S. Mithyantha. Rallis India Limited, Bangalore, 1978. Pp. 173. Price; India Rs30; elsewhere £4.00 + postage.

TWELVE LITTLE HOUSEMATES. Karl von Frisch. Pergammon Press, 1979. ISBN 0 08 021958 6. pp. 155. Price £5.00, US $12.00.

PLANT BREEDING FOR PEST AND DISEASE RESISTANCE. G. E. Russell. Butterworth &; Co Ltd, Sevenoaks, 1978. ISBN 0 408 106131. pp. 485. Price £25.00.     

浑水灌溉入渗特性研究进展与展望

在综合国内外相关研究文献的基础上,分析了浑水入渗机制和浑水入渗模型方面的研究进展。从研究成果中可以得出:利用静水做浑水灌溉入渗试验的较多,而利用动水做浑水灌溉入渗试验研究的比较少;不同含沙率对土壤入渗的影响研究方面研究成果比较多,而对不同的泥沙粒度组成对土壤入渗的影响研究较少;一次浑水灌溉土壤入渗研究较多,而致密层形成后进行二次灌溉情况下的土壤入渗研究较少;在室内利用下渗环等试验设备进行土壤入渗试验的较多,而在大田实验土壤入渗试验方面的研究较少;在裸地做土壤入渗试验的较多,而在有种植作物的大田上进行土壤入渗试验的较少。为了更深入的进行浑水灌溉下的土壤入渗机制的研究,建议以后试验中考虑浑水灌溉中动水入渗试验方面的研究,并将不同泥沙粒度组成对土壤入渗的影响、大田作物的影响、多次浑水灌溉对土壤入渗的影响以及浑水灌溉条件下水肥耦合方面的试验研究和浑水膜孔灌溉方面的试验研究等作为研究的重点,逐步深入的研究浑水灌溉入渗特性,为实际应用提供理论依据。     

Translocation of 2,4-D, asulam and amitrole in water hyacinth

In glasshouse experiments foliar application or ¹⁴C-labelled herbicides to water hyacinth plants at the 4-leaf stage indicated that amilroie transport from the treated leaf blade was faster and greater than 2.4-D. but a little less than asulam. From the treated leaf 14·2, 25·9. 39·7. 44·5 and 51·8% of the recovered ¹⁴CNamitrole was translocated at intervals of 6 h. and 1. 3. 6 and 12 day., respectively. Both xylem and phloem transport of asulam and amitrole was evident, whereas 2.4-D moved only from ‘source to sink’. Movement of the herbicides from the mother to the connected daughter plant or vice versa was dependent upon the size of the latter. Maximum transport of these herbicides in either direction took place at the 2-leaf stage of daughter plants. With any increase or decrease in the number of leaves on daughter plants, the transport of herbicides was reduced. As an exception, daughter plant to mother plant movement of amilroie was maximum at the 1-leaf stage. After extraction, fractionation and TLC separation of foliage applied ¹⁴C-2.4-D 76–4 and 72·1% of the radioactivity was detected in the chloroform phase of the leaf extract at 3 and 6 day intervals, respectively. In another pot culture experiment, it was observed that after spraying the mother plants with 2.4-D-amine at 0–75 kg/ha the connected daughter plants at 1 to 4-leaf stages werckilled if the culture solution was contaminated while spraying, or by dying leaves. When contamination was totally avoided, the connected but unsprayed daughter plants at 3 to 4-feaf stages survived.