基于GIS的河南省不同区域小麦氮磷钾推荐量与施肥配方

  【目的】  河南省是我国小麦种植大省,明确河南省不同区域小麦氮、磷、钾肥推荐用量,建立施肥配方图,对于当地小麦配方肥生产与合理施肥具有重要意义。  【方法】  河南省按照地理条件划分为平原适宜区、稻麦轮作区、南部盆地区、中部丘陵区、西部山地区5个区域。本研究共收集了2829组小麦田间试验和83.71万组土壤养分数据 (1247组“3414”试验和1582组“三区示范”试验),分析了其中农民习惯施肥产量、目标产量及单位籽粒磷素需求量;根据氮肥肥效反应,计算各个区域的小麦氮肥推荐总量;根据土壤有效磷、速效钾含量与缺素区相对产量的关系,以相对产量80%、85%、90%、95%为标准,建立土壤有效磷、速效钾的丰缺指标;进一步根据“磷肥恒量监控”、“钾肥肥效反应”方法,计算各个区域的小麦磷、钾肥推荐施用量;借助ArcGIS软件,将河南省小麦氮、磷、钾肥推荐施用量图层进行叠加,换算成含量为45%的施肥配方,建立河南省不同区域的小麦施肥配方与配方图。  【结果】  河南省小麦目标产量以平原适宜区最高,为8671 kg/hm2,稻麦轮作区为5950 kg/hm2,南部盆地区为7780 kg/hm2,中部丘陵区为7590 kg/hm2,西部山区为7400 kg/hm2。各区域经济最佳施氮量拟合结果,推荐施氮量以南部盆地区最高,为178 kg/hm2,其次为平原适宜区 (170 kg/hm2),稻麦轮作区为160 kg/hm2,中部丘陵和西部山地区合并调整为150 kg/hm2。依据相对产量水平,河南省土壤有效磷极低、低、中、高、极高5个丰缺指标的值为 < 10、10～15、15～24、24～37、> 37 mg/kg,速效钾为 < 80、80～105、105～140、140～180、> 180 mg/kg。将土壤丰缺指标、校正系数与目标产量、磷需求量相结合,得到土壤有效磷由高到低5个磷肥 (P₂O₅) 推荐水平分别为63、75、81、95、105 kg/hm2;按照速效钾含量 < 80、80～105、105～140、140～180、> 180 mg/kg,钾肥推荐量 (K₂O) 分别为73、64、58、48、43 kg/hm2。在氮磷钾推荐用量基础上,建立了8个基肥+追肥配方和9个一次性基施配方,并建立了河南不同区域的施肥配方图。在基肥+追肥配方图中全省N–P₂O₅–K₂O 以15–19–11、16–17–12、17–16–12覆盖面积较大,在一次性基施配方图中以24–12–9和25–12–8所占的区域最大。  【结论】  河南省不同小麦种植区域的产量和土壤磷钾养分含量变异很大。氮肥推荐量依据目标产量而定,磷钾肥在目标产量需求量的基础上,结合土壤含量水平分别推荐了5个磷、钾肥水平。经校对与合并,基于小麦基追两次施肥和一次基施,分别提出了8个和9个专用肥配方。     

豫东潮土区大蒜氮磷钾推荐施肥研究

通过大蒜氮肥用量和丰缺指标多点田间试验研究,采用Excel进行统计分析,建立不同氮肥用量与产量的效应函数,推荐大蒜氮肥用量369.9 kg/hm2;以土壤中速效磷、速效钾养分的测定值及其相对产量拟合回归方程,再以相对产量的55%、75%、80%、90%划分土壤养分丰缺指标,同时结合大蒜的目标产量,进行磷、钾施肥量的推荐,分别为200、300 kg/hm2。     

基于GIS和丰缺指标法的区域施肥管理体系的构建

  【目的】  采用GIS定位和养分丰缺指标相结合的方法,研究西辽河平原耕地土壤碱解氮、有效磷、速效钾的空间分布特点,建立直观、精准的推荐施肥系统。  【方法】  西辽河平原包括科尔沁区、开鲁县、奈曼旗、科尔沁左翼后旗、科尔沁左翼中旗。以该区域的15421个土壤测试数据和143个玉米“3414试验”数据为基础,运用GIS方法计算耕地土壤碱解氮、有效磷、速效钾的空间插值结果,结合土壤丰缺指标,将西辽河平原耕地土壤碱解氮、有效磷、速效钾养分分区,确定不同土壤氮磷钾养分组合下的施肥量,并制作玉米氮磷钾分区施肥图。  【结果】  西辽河平原耕地土壤养分空间分布不均,大部分土壤碱解氮含量较低,有效磷、速效钾含量中等。耕地土壤有效氮、磷、钾养分含量呈低氮–中磷–中钾 (碱解氮 ≤ 69.5 mg/kg、有效磷4.18～10.40 mg/kg、速效钾90.3～152.5 mg/kg)、中氮–中磷–中钾 (碱解氮69.5～107.9 mg/kg、有效磷4.18～10.40 mg/kg、速效钾90.3～152.5 mg/kg)、中氮–中磷–高钾 (碱解氮69.5～107.9 mg/kg、有效磷4.18～10.40 mg/kg、速效钾 > 152.5 mg/kg) 的面积占比分别为42.4%、14.1%、13.5%。土壤碱解氮、有效磷、速效钾含量 (x) 与经济最佳施肥量 (y) 之间存在较好的对数关系,氮施肥模型y = –102.5ln(x) + 617.22,磷施肥模型y = –36.11ln(x) + 174.1,钾施肥模型为y = –25.89ln(x) + 180.96。不同土壤养分组合种植玉米所需的经济最佳N–P₂O₅–K₂O用量 (kg/hm2) 组合分别为202–110–58、168–107–57、164–102–47。  【结论】  土壤碱解氮、有效磷、速效钾含量与相对产量存在较好的对数函数关系。西辽河灌区土壤有效氮磷钾丰缺指标的划分以75%和85%作为相对产量的分级区间较为合适。在土壤有效氮磷钾养分大数据的支撑下,采用GIS和丰缺指标法相结合的方法,可以准确快捷地构建区域施肥管理体系。     

黑龙江省典型黑土区玉米优化施肥——以双城为例

为明确黑龙江省玉米主产区土壤养分限制因子,充分发挥土壤及肥料的增产潜力,达到玉米的高产高效,通过双城市5年的田间小区对比试验,研究了玉米对不同肥料的产量响应及肥料效应。结果表明,不施氮磷钾锌硫肥均降低玉米产量,不施氮肥、不施磷肥、不施钾肥、不施锌肥、不施硫肥的各减素处理较推荐施肥处理平均减产分别为27.7%、18.4%、17.6%、7.8%和9.7%。氮磷钾合理配施显著提高玉米产量、养分吸收、农学效率和肥料利用率。与农民习惯施肥处理相比,优化施肥处理玉米平均增产12.6%,增加氮磷钾养分吸收量分别为13.4 kg·hm-2、9.0 kg·hm-2和12.4 kg·hm-2;增加氮磷钾农学效率分别为6.5 kg·kg-1、17.5 kg·kg-1、7.0 kg·kg-1;提高氮磷钾肥利用率分别为8.1%、13.4%和9.5%。影响双城市玉米产量的主要土壤养分限制因子是氮,其次是钾和磷,潜在因子是锌和硫。与优化施肥相比,该地区玉米生产农民习惯施肥中,氮施用量略有不足,磷肥用量过高,钾肥用量过低,生产中应适当增加钾肥用量,否则长期种植玉米易造成土壤钾素的亏缺。图3,表5,参20。     

基于养分专家系统的西北旱地冬小麦推荐施肥效应研究

  【目的】   本研究调查了养分专家系统 (Nutrient Expert, NE) 推荐施肥在西北旱地冬小麦生产上的应用效果,以明确该方法在西北旱地小麦推荐施肥中的可行性。   【方法】   在陕西渭北旱塬两年共布置15个田间试验,所有试验均设置两个处理:养分专家系统推荐施肥 (NE) 和农户习惯施肥 (FP)。在小麦成熟期采集小麦样品和0—100 cm土层土壤样品,测定植株氮磷钾养分含量和土壤硝态氮含量,调查分析小麦产量及其构成要素、经济效益和肥料偏生产力。   【结果】   NE推荐的N施用量平均为158 kg/hm2,较FP处理 (N 192 kg/hm2) 减少了18%;P₂O₅施用量平均为62 kg/hm2,较FP处理 (134 kg/hm2) 减少了54%;而K₂O用量为40 kg/hm2,较FP处理 (28 kg/hm2) 增加了43%。NE处理的冬小麦平均籽粒产量为5171 kg/hm2,与FP处理 (5111 kg/hm2) 籽粒产量接近,经济效益提高了7.8%,氮肥偏生产力提高25.1%,磷肥偏生产力提高了139.8%。与FP相比,NE处理的土壤0—100 cm土层硝态氮残留量无显著差异。   【结论】   相比农户习惯施肥,基于养分专家系统推荐的施肥方案减少了18%的氮肥和54%的磷肥用量,增加了43%的钾肥用量,冬小麦产量保持稳定,氮肥和磷肥的偏生产力和经济效益均显著提升,具有较好的化肥减施和增收效果,可在旱地冬小麦生产中推广应用。     

近14年北方冬小麦肥料产量效应变化及优化施肥方案

  【目的】  通过分析近14年来北方冬小麦肥料产量效应的多点试验数据，明确北方冬小麦产量变化特征及肥料产量效应，为该区冬小麦养分管理和合理施肥提供科学依据。  【方法】  通过我国北方冬小麦区2002—2016年96个定位监测试验，研究小麦地力产量和肥料农学效率变化趋势；通过120个田间肥料效应的检验试验，研究不同时段和不同施肥水平时氮、磷、钾在冬小麦上的产量效应；以肥料农学效率变化和施肥产量效应为依据，通过24个田间试验对习惯施用的复合肥配方进行田间校验，提出相应的节肥增效建议。  【结果】  1) 2002—2016年间，北方冬小麦区的土壤供肥能力呈逐渐增加的趋势，其平均地力产量自2002年的4721 kg/hm2增加到2016年的5828 kg/hm2，年均增加1.6%。施肥能显著增加小麦产量，但施肥增产率从2005年后呈下降趋势，由2005年的30.9%下降至2016年的20.2%。2) 2002—2016年，肥料的农学效率呈下降趋势，由2002年的9.0 kg/kg下降至2010年的6.7 kg/kg，2010年后维持在6.3～6.7 kg/kg。3) 基于不同时段氮、磷、钾在冬小麦上的产量效应函数计算出经济施肥量，其中2002—2006年间，最高产量的N、P₂O₅、K₂O施用量分别为180.5、107.4、55.9 kg/hm2；经济最佳用量分别为167.8、102.5、53.7 kg/hm2；经济合理用量 (R = 0.1) 分别为155.5、99.9、52.8 kg/hm2；2012—2016年间，最高产量的N、P₂O₅、K₂O施用量分别为184.3、125.1、52.4 kg/hm2；经济最佳用量分别为171.7、118.5、48.6 kg/hm2；经济合理用量分别为159.2、114.9、47.0 kg/hm2；优化复合肥N–P₂O₅–K₂O配方为16–20–8，比常规原配方减少氮磷钾总用量的12.0%。  【结论】  从2002年到2016年，北方冬小麦区土壤地力产量逐渐提高，虽然施肥仍有显著增产效果，但增产率和农学效率呈逐渐降低的趋势，2016年施肥增产率为20.2%，肥料农学效率维持在6.5 kg/kg。北方冬小麦N–P₂O₅–K₂O优化配方为16–20–8，推荐施肥方案为:基肥该配方肥600 kg/hm2，追施氮69 kg/hm2。     

福建甘薯氮磷钾施肥指标研究

根据近年来在甘薯主产区完成的118个氮磷钾肥效田间试验结果,建立甘薯氮磷钾施肥指标体系,包括甘薯施肥效应和土壤肥力分级、土壤速效氮磷钾丰缺指标、不同产量水平的氮磷钾最佳用量和比例、土测值与最佳施肥量关系式以及施肥时期和施肥方法等5个方面内容。结果表明,土壤对甘薯产量的平均贡献率为62.5%,氮磷钾平均增产效果是N>K>P,均达显著水平;土壤碱解氮、Olsen-P和速效钾的高产临界指标分别为176 mg kg-1、17 mg kg-1和106 mg kg-1;平均经济施肥量是N165kg hm-2、P2O5 63 kg hm-2、K2O 204 kg hm-2,比例为1∶0.38∶1.24,但不同土壤肥力等级的推荐施肥量存在较大差异;土壤速效氮磷钾土测值与最佳施肥量之间满足指数模型,该式实现了根据土测值预测具体地块推荐施肥量的目的。研究结果为福建甘薯高效施肥提供了科学依据。     

基于GIS和测土配方数据的晋北县域春玉米专用肥配方筛选

为改善当前施肥过高或过低等问题,促进区域合理施肥,该研究依据测土配方施肥项目田间试验数据和土样分析数据,以应县为研究区域,遵循"氮肥总量控制,分期调控及磷、钾恒量监控"的技术原理,利用地理信息系统(geographic information system,GIS)技术开展县域春玉米专用肥配方筛选研究。采用肥料效应函数法对测土配方施肥项目田间试验数据进行模拟分析,确定研究区域平均适宜施氮用量为200 kg/hm2,其中80 kg/hm2氮素作为播种前基肥,120 kg/hm2作为大喇叭口期追肥。综合利用养分丰缺指标法、肥料效应函数法建立磷、钾养分丰缺指标及磷、钾肥的推荐施肥指标体系。基于GIS技术形成区域土壤养分分布图、氮磷钾养分推荐用量图,制定区域氮磷钾养分配方图,并筛选出适合县域推广的春玉米专用肥大配方。结果表明,应县氮磷钾养分空间变异特征明显,形成的11个专用肥配方经筛选后最优春玉米专用肥配方为20-17-8(为专用肥氮磷钾养分含量比例,即N-P2O5-K2O,专用肥总养分45%)、17-19-9和21-12-12。该研究将GIS技术和测土配方施肥技术有机结合,促进了测土配方施肥项目结果推广应用,为县域春玉米养分资源高效利用提供了参考。     

潮土区麦田土壤有效磷施肥指标及小麦施磷推荐-基于ASI法的土壤养分丰缺指标

运用ASI法测定的潮土区小麦土壤有效磷含量分别与不施磷小麦相对产量呈显著正相关关系。根据小麦相对产量<50%,50%～65%,65%～75%,75%～95%和>95%对应的土壤有效磷指标,可以得出潮土区土壤有效磷"极低"指标为<7 mg/L,"低"指标为7～12 mg/L,"中"指标为12～18 mg/L,"较高"指标为18～38mg/L,"高"指标为>38 mg/L。据此建立的麦田土壤养分丰缺指标推荐施磷量:土壤有效磷含量小于7 mg/L,推荐磷肥用量为135 kg/hm2;土壤有效磷含量在7～12 mg/L之间时,磷肥用量推荐为105 kg/hm2;土壤有效磷含量在12～18 mg/L之间时,磷肥用量推荐为90 kg/hm2;土壤有效磷含量在18～38 mg/L之间时,磷肥用量推荐为60 kg/hm2;土壤有效磷含量大于38 mg/L,建议不施或者少施磷肥。     

甘肃中部灌区春小麦土壤氮磷钾 养分丰缺指标及施肥指标研究

在甘肃中部引黄灌区及井灌区连续多年多点对春小麦氮磷钾土壤养分丰缺指标开展田间试验研究,建立本地灌区春小麦土壤有效养分与缺素区相对产量及氮磷钾最佳施肥量之间的函数模型,确定土壤氮、磷、钾养分丰缺指标和推荐施肥指标。结果表明:现阶段当地灌区小麦相对产量50%(极低)、50%～60%(低)、60%～70%(较低)、70%～80%(中)、80%～90%(较高)、90%(高)6个肥力等级的土壤氮、磷、钾养分丰缺指标划分为全氮0.35、0.35～0.5、0.5～0.8、0.8～1.3、1.3～2.0、2.0 g/kg;有效磷(P)5、5～10、10～15、15～25、25～45、45 mg/kg;速效钾(K)65、65～90、90～130、130～185、185～265、265mg/kg。在正常年份降水及灌溉条件下,对应推荐施N量分别为285、255～285、235～255、200～235、170～200、170 kg/hm~2,施P_2O_5量分别为140、110～140、95～110、85～95、65～85、65 kg/hm2;施K2O量分别为70、65～70、45～65、35～45、25～35、25 kg/hm2。试验研究表明,当地灌区土壤氮素养分仍处于低水平;磷素养分处于中等水平;而钾素养分与以往相比有所下降,但依然处于中等较丰富水平。生产中春小麦应当合理增施氮肥,适度施用磷肥,适当增施钾肥。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分，因此，各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中，在细菌、真菌中已经对氮素营养信号有了较好的研究，而植物中则相对缓慢，但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成，以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Aircraft operations near concentrations of birds in Antarctica: The development of practical guidelines

Aircraft operations have the potential to disturb and to impact negatively on bird life. A gradient of increasing behavioural response is evident in birds when exposed to increasing aircraft stimulus. The most major disturbance is likely to lead to impacts on the health, breeding performance and survival of individual birds, and perhaps bird colonies. A process of revision to policies on aircraft operations contained in management plans for a number of specially protected areas in Antarctica by the United Kingdom, accompanied by consultations made within the scientific community through the Scientific Committee on Antarctic Research (SCAR) and with operational interests through the Council of Managers of National Antarctic Programmes (COMNAP) resulted in new guidelines being adopted by the Antarctic Treaty Consultative Parties in June 2004. The principal recommendations of the guidelines are that bird colonies should not be overflown below 2000 ft (∼610 m) above ground level and landings within 1/2 nautical mile (∼930 m) of bird colonies should be avoided wherever possible. These guidelines are less stringent and less specific than those that were recommended by the SCAR specialist group on birds, and represent a compromise to accommodate operational needs. While the adoption of clear and consistent guidelines for the operation of aircraft in Antarctica is welcome in that this provides practical advice that is likely to reduce incidences of close aircraft/bird encounters, there remains insufficient knowledge of the interactions between aircraft and birds in Antarctica, and the consequent impacts on individual birds and on bird populations. It is important, therefore, that the guidelines adopted are considered interim, and should be kept under scrutiny with revisions made as new and improved research results appear.     

The abundance of heterocystous blue-green algae in rice soils and inocula used for application in rice fields

Summary Algal populations were quantified (as colony-forming units [CFU] per square centimetre) in 102 samples of rice soils from the Philippines, India, Malaysia and Portugal, and in 22 samples of soil-based inocula from four countries. Heterocystous blue-green algae (BGA) were present in all samples. Nostoc was the dominant genus in most samples, followed by Anabaena and Calothrix. In soils, heterocystous BGA occurred at densities ranging from 1.0 × 10² to 8.0 × 10⁶ CFU/cm² (median 6.4 × 10⁴) and comprised, on average, 9% of the total CFU of algae. Their abundance was positively correlated with the pH and the available P content of the soils. In soil-based inocula, heterocystous BGA occurred at densities ranging from 4.6 × 10⁴ to 2.8 × 10⁷ CFU/g dw (dry weight), comprising only a moderate fraction (average 13%) of the total algae. In most soils, the density of indigenous N₂-fixing BGA was usually higher than that attained by applying recommended rates of soil-based inoculum. Whereas research on the practical utilization of BGA has been mostly directed towards inoculation with foreign strains, our results suggest that attention should also be given to agricultural practices that enhance the growth of indigenous strains already adapted to local environmental conditions.Maître de Recherches ORSTOM (France), Visiting Scientist at IRRI