Testing insecticide resistance management strategies: mosaic versus rotations

BACKGROUND: Developing scientifically valid, economically acceptable insecticide resistance management (IRM) programs is critical for sustainable insect management. The diamondback moth, Plutella xylostella (L.), has demonstrated an ability to develop resistance to many different classes of insecticides, including proteins produced by the bacterium Bacillus thuringiensis Berliner (Bt). Recently it has developed resistance to the novel compounds spinosad and indoxacarb. In greenhouse cage experiments, a laboratory‐selected population of P. xylostella resistant to spinosad, indoxacarb and Bt was used to compare population growth and resistance evolution if these three insecticides were rotated or used in a mosaic fashion. RESULTS: The average population density through nine generations was lowest in the treatment in which the insecticide was rotated every generation (R‐1) (x? = 20.7 ± 3.20) compared with the treatment in which the insecticide was rotated every third generation (R‐3) (x? = 41.4 ± 17.6) or where the insecticides were applied as a mosaic (M) (x? = 41.8 ± 6.53). After nine generations, the survival of resistant individuals increased for each insecticide (7.2–73.5%) compared with the population without selection (CK) (0.73–3.1%). Survival on spinosad was significantly lower (23.7%) in the single‐generation rotation than for the other two treatments, both of which exceeded 72%. The calculated survival on all three insecticides treated simultaneously, according to the survival on each insecticide, was 0.26, 0.81 and 1.6% for R‐1, R‐3 and M treatments respectively. CONCLUSION: Results of both population density and resistance development indicated that insecticide rotation every generation was better for IRM than if the insecticide was rotated every third generation or if the three insecticides were applied as a mosaic. Copyright © 2010 Society of Chemical Industry     

Experiences and Research Perspectives on Sustainable Development of Rice-Wheat Cropping Systems in the Chengdu Plain,China

The rice and wheat cropping pattern is one of the main cropping systems in the world. A large number of research results showed that successive cropping of rice and wheat resulted in a series of problems such as hindering nutrition absorption, gradual degeneration of soil fertility, decline of soil organic matter, and increased incidence of diseases and pests. In China, especially in the Chengdu plain where rice-wheat cropping system is practiced, productivity and soil fertility was enhanced and sustained. This paper reviews the relevant data and experiences on rice-wheat cropping in the Chengdu Plain from 1977 to 2006. The principal sustainable strategies used for rice-wheat cropping systems in Chengdu Plain included： 1） creating a favorable environment and viable rotations; 2） balanced fertilization for maintenance of sustainable soil productivity; 3） improvement of crop management for higher efficiency; and 4） use the newest cultivars and cultivation techniques to upgrade the production level. Future research is also discussed in the paper as： 1） the constant topic： a highly productive and efficient rice-wheat cropping system for sustainable growth; 2） the future trend： simplified cultivation techniques for the rice-wheat cropping system; 3） the foundation： basic research for continuous innovation needed for intensive cropping. It is concluded that in the rice-wheat cropping system, a scientific and reasonable tillage/cultivation method can not only avoid the degradation of soil productivity, but also maintain sustainable growth in the long run.     

内蒙古阴山北麓马铃薯与绿肥作物轮作研究

在旱作区进行绿肥作物与马铃薯轮作研究,结果表明,苕子和豌豆增施N、P化肥均有显著的增产效果,增产可达13.0%～36.0%。箭筈碗豆增产效果好于蒙苕一号。尽管马铃薯平衡施肥的茬口后效最好,但与绿肥作物各施磷酸二铵处理之间没有显著差异。毛叶苕子和箭筈碗豆两种绿肥作物茬口对后茬马铃薯产量基本没有影响。绿肥后茬减少施N量30%,减产不明显,说明在干旱地区种植绿肥后可以减少N肥用量30%。     

长期稻-稻-紫云英轮作28年对水稻产量及田间杂草多样性影响

为探讨湘南红壤稻田多熟制的增产潜力,不断提高经济效益和土壤肥力,促进农业可持续发展,为生产示范、领导决策提供科学依据,从1982年开始,在湖南祁阳官山坪中国农业科学院红壤站的红壤稻田布置了长期稻-稻-紫云英轮作制度长期定位试验。试验设四个处理,即：稻-稻-紫云英（豆科）、稻-稻-油菜（十字花科）、稻-稻-黑麦草（禾本科）、稻-稻-冬闲。28年研究结果表明：1.长期稻-稻-紫云英轮作能促进水稻增产;2.长期稻-稻-紫云英轮作能够明显的降低田间杂草密度,减少早稻期间田间杂草的种类,但对晚稻时期田间杂草种类的影响不明显。3. 稻-稻-紫云英轮作是一种值得推广的种植模式。     

稻麦两熟制农田不同土壤耕作方式对稻季CH_4排放的影响

【目的】研究稻麦两熟制农田不同土壤耕作方式对水稻生长季CH4排放的影响,为长江下游稻麦两熟制农田温室气体减排提供对策。【方法】采用裂区设计,利用静态暗箱-气相色谱法研究麦季土壤耕作方式(免耕、旋耕和翻耕)和稻季土壤耕作方式(旋耕和翻耕)对水稻生长季CH4排放的影响。【结果】稻麦两熟制农田不同土壤耕作方式下水稻生长季CH4排放呈先升高后降低的变化趋势,移栽至有效分蘖临界叶龄期CH4累积排放量占全生育期排放总量的比例为64.73%—86.84%。水稻生长季CH4排放总量麦季免耕极显著高于麦季旋耕和麦季翻耕,平均增加53%和24%;稻季翻耕较稻季旋耕平均增加CH4排放量10%,差异达显著水平。不同土壤耕作处理稻季CH4排放总量为:麦季免耕+稻季翻耕麦季免耕+稻季旋耕麦季翻耕+稻季翻耕麦季翻耕+稻季旋耕麦季旋耕+稻季翻耕麦季旋耕+稻季旋耕,"单位产量的CH4排放量"表现趋势相同。水稻生长期内CH4排放通量的季节变化和土壤Eh呈极显著负相关,CH4排放总量与0—5cm耕层土壤有机质含量呈极显著正相关。【结论】麦季土壤耕作方式和稻季土壤耕作方式对水稻生长季CH4排放总量有显著或极显著影响,在长江下游稻麦两熟制农田采用周年旋耕措施能有效减少水稻生长季CH4的排放。     

水旱轮作条件下免耕土壤微生物生物量变化特征及其活性评价

研究长期免耕土壤微生物活性能及时准确反映免耕土壤质量的演变趋势,探求最佳免耕年限。通过野外调查和室内分析,调查了水旱轮作条件下,不同免耕年限土壤微生物量的变化,并采用主成分分析法对土壤微生物活性进行了综合评价。结果表明:①旱作和水作后,免耕土壤微生物量碳、氮均显著高于常规每年翻耕的耕作方式,微生物量磷则相反。随着免耕年限延长,旱作土壤微生物量碳、氮均呈逐渐降低的趋势;水作后,则呈先增加再降低的趋势;而微生物量磷在不同免耕年限间无显著差异。②主成分分析表明,旱作后免耕土壤微生物活性高于常规每年翻耕,水作后则相反。随着免耕年限延长,免耕土壤微生物活性呈先降低再增加的趋势,旱作后免耕7—8 a土壤微生物活性最低,水作后免耕5—6 a土壤微生物活性最低。     

不同轮作方式对牡丹江地区烟田土壤微生物数量及分布的影响

采用稀释平板培养法,分析不同轮作方式下牡丹江地区烟田土壤微生物数量及其主要生理类群分布规律。结果表明:3大类土壤微生物中细菌数量占绝对优势,占总菌数的99%以上;放线菌次之,真菌最少。烟田土壤微生物各主要生理类群中,好气性纤维素分解菌数量最多,氨化细菌次之,好气性固氮菌最少。各土层土壤微生物类群间具有较为显著的相关性。不同轮作方式对烟田土壤微生物的数量和分布会产生很大影响,微生物总数量上,轮作样地(I1、I2、I3)及迎茬样地(I5)显著高于连作样地(I4、I6),连作4a地块(I4)微生物数量少于连作1a地块(I6),说明连作对土壤微生物的影响会随着连作年数的增加而加剧。     

烟稻轮作的精细化气候区划研究

针对烤烟生产的关键气象因子,分析对比瑞金与国内外其他烟叶种植区的气象条件,建立了评价指标,运用GIS技术对瑞金市烟稻轮作进行了气候区划。结果表明,瑞金市光、热资源丰富,大部分地区适宜推广烟稻轮作的栽培模式;600～800m的一季稻区,适宜开展单季轮作,开展优质烟叶生产;在海拔高度350～600m的双季稻和一季稻共存区,可实行烟＋早中熟晚稻轮作制,开展优质烟叶生产;在海拔高度150～350m的双季稻区,可实行烟＋迟熟晚稻轮作制,但应注意防御高温低湿天气对烟叶造成的危害;150m以下或800m以上的地区不适宜推广烟稻轮作。     

Productivity of three successive rotations of P. radiata plantations in South Australia over a century

In the southeast of South Australia and the adjacent south west of Victoria (called the Green Triangle Region), planting of Pinus radiata D. Don (radiata pine) plantations began about 130 years ago and these now occupy 175,000 ha. They are growing on sites with generally podsolised sandy soils, low in soil fertility and where evaporation typically exceeds precipitation for five to six months of the year. Regional softwood industries producing a range of value added products are completely dependant on the versatile radiata pine wood from these plantations.     

传统施肥下农田土壤氮素累积特征研究

深入研究土壤中氮素的残留和移动有助于明确、解释或监测农田氮素淋失的过程。以土壤无机氮测试为主要手段,通过设置不同的田间试验处理,分析农民传统施肥下冬小麦/夏玉米轮作条件下氮素的累积迁移特征。结果表明,农民习惯施肥处理冬小麦/夏玉米轮作地土壤中残留的氮素以硝态氮为主,小麦生长季土壤硝态氮积累量在90.13~426.97 kg/hm2,玉米季为67.96~204.32 kg/hm2,存在潜在淋失的风险。除因作物不同生育期吸收不同外,N肥施用量、灌溉量等都是决定其季节动态变化的主要因素。进一步研究需寻求合理的水肥管理模式,以提高氮肥利用率,减少氮素流失造成的非点源污染。