不同施用量水稻灰对作物及退化黄壤理化性质的影响

以退化黄壤为对象,通过莴笋盆栽试验,研究了不同施用量的水稻灰(0,10,25,50,100,250g/kg)对作物品质及退化黄壤理化性质的影响,并进一步分析了水稻灰不同施用量下土壤液塑限的变化。结果表明:(1)水稻灰的施用提高了莴笋氨基酸和还原糖含量,以施用量为50~100g/kg的处理效果较佳,但仅施用量为50g/kg时的莴笋硝酸盐与处理I(0g/kg)比较减少了54.9%;水稻灰施用能提高莴笋中全氮、全磷、全钾含量,且随着灰渣施用量的增加而逐渐升高,但过量水稻灰处理(250g/kg)的莴笋全氮、全磷含量的增加量较其他灰渣处理明显减少。(2)水稻灰处理提高了退化黄壤pH值,改善了土壤酸化情况,其中处理V(100g/kg)的退化黄壤pH值由4.84上升至7.13。水稻灰施用可有效提高土壤有效磷和速效钾含量,但对碱解氮的作用并不明显。(3)各处理0.25mm土壤团聚体水稳定性表现为处理V(100g/kg)处理IV(50g/kg)处理III(25g/kg)处理VI(250g/kg)处理II(10g/kg)处理I(0g/kg),其中处理V的0.25mm团聚体破坏率由63.1%减至17.6%,同时对0.25mm土壤团聚体水稳定性提高效果最佳,但过量施用水稻灰(250g/kg)改良效果降低,0.25mm团聚体破坏率达到了42.4%。土壤液、塑限则随水稻灰施用量增加而增加,其中250g/kg水稻灰处理分别为31.67%,46.8%,有效提高了退化黄壤的保水能力。总体上,水稻灰施用量在50~100g/kg时,对退化土壤的养分环境、物理结构及作物养分品质的综合改良效果最佳。     

生物炭对两种典型植烟土壤养分、碳库及烤烟产质量的影响

为探讨生物炭对江西植烟土壤肥力和烤烟致香物的影响,2015年在江西省信丰县西牛镇进行水稻土和紫色土田间试验,生物炭穴施增施量设置为T1(0 kg hm~(-2))、T2(450 kg hm~(-2))、T3(900 kg hm~(-2))、T4(1350 kg hm~(-2))、T5(1800 kg hm~(-2))五个水平。结果表明:(1)增施生物炭后,水稻土和紫色土速效养分含量,全碳、有机碳、水溶性碳、C/N都有所增加。(2)水稻土pH随着生物炭施用量的增加而增加,T2降低了紫色土pH。(3)增施生物炭提高了紫色土易氧化态碳含量和碳库管理指数,以T2处理效果最为显著,水稻土除T3处理外,其他处理易氧化态碳含量和碳库管理指数均低于T1处理。(4)增施生物炭提高了水稻土有机碳氧化稳定性,降低了紫色土有机碳有机碳氧化稳定性,生物炭在水稻土中更加稳定。(5)施用生物炭对两种土壤不同部位烟叶中性致香物影响不同。(6)施用生物炭后水稻土和紫色土烤烟分别最高增产52.94%和122.75%。综上所述,在水稻土和紫色土中增施生物炭可以提高土壤质量和烤烟产质量,分别以常规施肥增施900 kg hm~(-2)和450 kg hm~(-2)时效果最好。     

生物质炭与秸秆配施对紫色土团聚体中有机碳含量的影响

以油菜/玉米轮作农田生态系统为研究对象,通过田间微区试验,研究了生物质炭、秸秆(BC:8 000 kg·hm~(-2)生物质炭、CS:8 000 kg·hm~(-2)秸秆、0.5BC:4 000 kg·hm~(-2)生物质炭、0.5CS:4000kg·hm~(-2)秸秆、BC+CS:4 000 kg·hm~(-2)生物质炭+4 000 kg·hm~(-2)秸秆)与化肥配施对紫色土团聚体含量及稳定性、土壤有机碳及有机碳在各粒级团聚体中分布的影响,为合理利用有机物料及为紫色土培肥提供依据。结果表明:(1)与对照(CK)相比,秸秆、生物质炭还田(除0.5BC处理外)均能提高2 mm粒级团聚体含量,降低0.053 mm粒级团聚体含量,同时提高水稳性团聚体的平均重量直径(MWD)、几何平均直径(GMD)、大于0.25 mm团聚体含量(R_(0.25)),其中只有CS处理达到了显著水平,且随着秸秆施用量增加,效果越显著。CS+BC处理则能显著提高0.25～2mm粒级水稳性团聚体含量。(2)除CS处理,其他各处理较CK均能显著提高土壤总有机碳含量,其中BC和CS+BC处理分别提高了45.55%和44.45%(P0.05),效果优于单施秸秆处理,且随着生物质炭施用量的增加,土壤总有机碳呈增加趋势。对不同粒级团聚体有机碳而言,各处理的团聚体有机碳主要分布在0.053mm和2mm粒级团聚体中;BC处理较其他处理能提高土壤不同粒级团聚体有机碳含量,其次为CS+BC处理。(3)通过计算团聚体有机碳贡献率发现,各处理对土壤团聚体有机碳贡献率主要分布在0.25～2 mm和0.053 mm粒级团聚体中,其中仅CS处理显著提高了2 mm粒级团聚体有机碳贡献率,较CK提高了53.53%;CS+BC、0.5BC处理分别较CK显著提高了0.053 mm粒级团聚体有机碳贡献率,增幅为26.20%,48.63%。(4)秸秆和生物质炭还田能提高玉米和油菜的生物产量和经济产量,其中CS、BC、CS+BC效果较明显。总之,秸秆与生物质炭配施是改善紫色土结构和提升碳水平的较优培肥措施。     

氮肥对盐渍化枸杞园土壤微生物群落和氨氧化微生物丰度的影响

研究主要分析氮元素对宁夏平罗盐渍化枸杞园土壤中氨氧化微生物(氨氧化细菌和氨氧化古菌)的影响。实验共设八个处理:(1)C(不施氮肥,不施脱硫废弃物,原始荒地);(2)不施氮肥(N0);(3)施氮肥25 kg hm~(-2)(N25);(4)施氮肥50 kg hm~(-2)(N50);(5)施氮肥100kg hm~(-2)(N100);(6)施氮肥200 kg hm~(-2)(N200);(7)施氮肥400 kg hm~(-2)(N400);(8)施氮肥800 kg hm~(-2)(N800),在N0-N800处理施用脱硫废弃物3.72×104kg hm~(-2)。2011年8月采集0~20 cm土样。结果显示:脱硫废弃物和氮肥配合施加对土壤理化性质产生了显著影响;NO_3~--N和NH_4~+-N含量在施氮处理中相对于原始样地和不施氮处理组都有显著的升高,微生物生物量和细菌和氨氧化细菌多样性指数在施氮400 kg hm~(-2)达到最大值,施氮肥400 kg hm~(-2)是促进微生物量和群落多样性增加的最佳施用量。实时荧光定量PCR结果显示:氨氧化细菌(AOB)丰度在施氮肥400 kg hm~(-2)和800 kg hm~(-2)显著高于其它处理,脱硫废弃物和氮肥配合施用对AOB的丰度具有叠加效应。相关性分析表明:NH_4~+-N与总磷脂脂肪酸(PLFA)、细菌PLFA、革兰氏阳性菌(G+)、革兰氏阴性菌(G-)、真菌/细菌(F/B)、微生物碳(MBC)、微生物氮(MBN)及16S r RNA基因拷贝数、AOB的基因拷贝数都显著相关。因此,铵态氮是该地区微生物群落可利用的有效氮素。     

密度和有机肥对苏北滩涂蓖麻群体生长及产量构成的影响

本研究于2013-2015年连续3年在江苏省大丰市金海农场沿海滩涂试验基地进行蓖麻种植密度和有机肥试验,探讨江苏沿海滩涂连续有机肥施用和种植密度对蓖麻群体生长和产量构成的影响。试验设高(18 000株·hm~(-2))、中(15 000株·hm~(-2))、低(12 000株·hm~(-2))3个种植密度与3个有机肥施肥水平(12 000 kg·hm~(-2)、6 000株·hm~(-2)和0 kg·hm~(-2))的田间小区互作试验。在蓖麻各生育期调查地上部干物质积累及其分配、叶面积指数、功能叶叶绿素含量、穗部性状及籽粒产量等指标。研究结果表明,连续3年施用有机肥可明显改善土壤养分状况,中密度下施用12 000 kg·hm~(-2)有机肥使开花期土壤全氮、有效磷、有效钾和有机质含量比不施有机肥处理分别升高47.37%、169.21%、54.65%和13.77%,达到显著水平(P0.05)。有机肥施用增加了中、低密度下蓖麻生长后期叶面积指数与功能叶叶绿素含量,对群体生长率产生了一定的促进作用,使得中密度群体地上部干物质积累量达到高密度水平。中密度群体增施有机肥还促进了干物质在花后生殖器官中所占比重,且单株有效穗数、单株粒数和百粒重随着有机肥施用量的增加而增加,有效补偿了密度降低带来的蓖麻群体产量降低,最终中密度处理下施用12 000 kg·hm~(-2)有机肥蓖麻获得最高产量(3 943.77 kg·hm~(-2)),与高密度群体差异不显著(P0.05)。由此可见,通过适当降低种植密度并增施有机肥能够有效合理地调控蓖麻群体生长,促进干物质的合理分配和转移,实现了保穗增重增产的目的。     

连施石灰对 Cd污染土壤 Cd形态及稻麦吸收 Cd的影响

为探索成都平原轻度Cd污染耕地有效治理措施,以稻麦轮作耕地为研究对象,采用田间试验,施加不同梯度石灰作为钝化剂,研究连续3年施加石灰后,对土壤Cd形态以及水稻、小麦籽粒吸收Cd的影响。结果表明,当每季石灰施用量为2 250 kg/hm~2时,稻麦产量较高,籽粒重金属Cd含量达到《食品安全国家标准-食品中污染物限量》(GB 2762-2012)规定的限值。当石灰施用量为1 500～3 000 kg/hm~2时,能有效提高土壤pH值,改善土壤酸性。随石灰用量的增加土壤Cd有效性降低,且水稻、小麦籽粒Cd含量也随之降低。与对照相比,每季石灰施用量为2 250和3 000 kg/hm~2的处理,水稻籽粒Cd含量分别降低到0.12和0.08 mg/kg;小麦籽粒Cd含量分别降低到0.097和0.075 mg/kg。施用石灰可促进土壤中可交换态Cd向可还原态和残渣态Cd转换,土壤可交换态Cd从对照的44.1%降至3 000 kg/hm~2石灰处理的29.0%;而残渣态从对照处理的18.8%升高到34.3%。     

轮作绿肥对盐碱地土壤性质、后作青贮玉米产量及品质的影响

为明确种植和翻压绿肥改良和培肥盐碱地的效果,采用田间试验研究了种植和翻压毛叶苕子(Vicia villosa Roth.)、田菁(Sesbania cannabina Poir.)、草木樨(Melilotus officinalis L.)、紫花苜蓿(Medicago sativa L.)、箭筈豌豆(Vicia sativa L.)和黑麦草(Lolium perenne L.)6种绿肥对中度苏打盐碱地土壤理化性质、返还土壤的N、P_2O_5和K_2O数量、后作青贮玉米(Zea mays L.)鲜草产量及蛋白质含量的影响。结果表明:与对照(不种植绿肥)相比,绿肥生长后期可显著提高土壤含水量1.0%~6.2%,使pH降低0.03~0.43,EC降低0.12~1.50 mS×cm~(-1);翻压绿肥可返还土壤N 15.6~195.4 kg×hm~(-2)、P_2O_5 5.3~58.8 kg×hm~(-2)和K_2O 34.5~127.9 kg×hm~(-2),使土壤有机质、全氮、碱解氮、速效磷和速效钾分别提高0.42~1.86 g×kg~(-1)、0.05~0.34 g×kg~(-1)、0.5~32.3 mg×kg~(-1)、0.42~4.65 mg×kg~(-1)和3.8~26.1 mg×kg~(-1);与对照相比,青贮玉米的鲜草产量和蛋白质含量分别增加1 294~19 391 kg×hm~(-2)和0.4~23.9 mg×g~(-1)。总体而言,种植和翻压豆科绿肥在保蓄土壤水分,降低土壤pH和EC,提升土壤有机质含量和N、P_2O_5、K_2O养分数量(特别是N素数量),提高青贮玉米鲜草产量与蛋白质等方面的效果均显著优于禾本科绿肥,其中以适应性强、生长快、生物量大的毛叶苕子处理的改良、培肥土壤,生产优质牧草的效果最好;其次是草木樨处理。种植和翻压豆科绿肥可有效改良中度苏打盐碱地,显著提高土壤肥力,提供无机养分替代部分化肥,提高优质牧草的生产,是适合大同盆地中度苏打盐碱地经济、有效和环保的改良模式,对稳定耕地面积、保证粮食安全具有重要意义。     

连续施用无害化污泥对沙质潮土土壤肥力和微生物学性质的影响

以小麦-玉米轮作体系下的沙质潮土为研究对象,选用经无害化处理后的城市污泥产物,通过2013~2015年田间定位试验,研究了不同城市污泥施用量对土壤肥力的影响,以期为城市污泥资源化利用提供理论基础和技术依据。设置单施化肥(CK)、CK+污泥15 t·hm~(-2)(CS1)、CK+污泥30 t·hm~(-2)(CS2)和CK+污泥45 t·hm~(-2)(CS3)共4个处理。主要研究结果如下:(1)连续定位试验结果表明,同一施用量污泥处理的土壤p H值随施用时间的增加呈下降趋势;土壤有机质(SOM)和养分含量如全氮(TN)、有效磷(AP)和速效钾(AK)随施用时间的增长呈上升趋势;(2)与CK比较,在2015年玉米季施用污泥各处理的土壤p H值显著降低了0.34~0.83个单位(P0.05),且与污泥施用量呈反比,以高施量污泥45 t·hm~(-2)下降最多;土壤SOM、TN、AP和AK分别显著提高了52.1%~166.9%、77.3%~177.8%、215.7%~486.3%和167.2%~379.0%(P0.05),且与污泥施用量呈正比,以高施量污泥45 t·hm~(-2)效果最显著;(3)试验所用污泥施用量范围内不会造成土壤和植物籽粒重金属污染,能够保持土壤环境健康;(4)与CK比较,施用污泥各处理土壤微生物量碳(MBC)、氮(MBN)含量均显著提高(P0.05),且与污泥施用量呈正比,并且季节不同也显著影响土壤MBC、MBN含量(P0.05);施用污泥能够显著提高土壤MBC/MBN(P0.05),说明施用污泥能够改变土壤微生物群落组成;(5)施用污泥,尤其是高施量污泥45 t·hm~(-2),在保证土壤和植物籽粒质量安全下,其土壤培肥效果最优。     

秸秆集中深还田对土壤水分特性及有机碳组分的影响

采用自主研制的"深开沟-覆土-合垄"翻转犁开沟,深度为40cm,将秋收后的玉米整株秸秆按0,6 000,12 000,18 000kg/hm2直接深还田,探讨该模式实施2a后对土壤水分特性及有机碳组分的影响。结果表明,土壤稳定入渗率表现为12 000kg/hm2(S2)6 000kg/hm2(S1)18 000kg/hm2(S3)CK;在同一水吸力下,秸秆上层土壤含水量表现为12 000kg/hm2(S2)18 000kg/hm2(S3)6 000kg/hm2(S1)CK,而在秸秆下层中则表现为12 000kg/hm2(S2)6 000kg/hm2(S1)18 000kg/hm2(S3)CK;各秸秆还田处理土壤ROC、POC、LFOC含量均随土层深度的增加而先增加后降低,且各组分含量与TOC呈正直线相关关系,达到1%的极显著水平,各组分碳含量均以12 000kg/hm2(S2)处理最高;土壤氧化稳定系数为CK秸秆深还田处理。由此说明,秸秆深还田能够提高土壤中水分的利用效率以及土壤中有机碳的固存,且以12 000kg/hm2(S2)处理效果最为显著。     

施氮对水稻产量、氮素利用及土壤无机氮积累的影响

通过田间试验研究了不同施氮量(0、60、120、180和240 kg hm~(-2))对水稻氮肥利用、产量、土壤氮素供应及氮素平衡的影响,结果表明,水稻产量随施氮量的增加呈先增后降的趋势,当施氮量超过180 kg hm~(-2)后产量下降,根据水稻产量(y)和施氮量(x)拟合,得出最佳施氮量为204 kg hm~(-2)。施用氮肥可显著增加水稻氮吸收总量,并随施氮量的增加显著增加,当施氮量超过180 kg hm~(-2)后,氮吸收总量不再显著增加。氮肥当季回收率、农学利用率、偏生产力和生理利用率均随施氮量的增加而下降,分别由44.0%、25.5 kg kg~(-1)、145.6 kg kg~(-1)和58.1 kg kg~(-1)下降至31.1%、13.6 kg kg~(-1)、43.6 kg kg~(-1)和43.7 kg kg~(-1)。氮收获指数表现为随施氮量的增加先增后降,以施氮量180 kg hm~(-2)处理最高,为68.7%。土壤无机氮(Nmin)含量在水稻整个生育期呈现先快速下降后缓慢升高的趋势,施氮处理各层土壤Nmin积累量与不施氮处理差异均达显著水平(P0.05),且基本随着施氮量的增加而增加。水稻成熟期土壤残留Nmin量和表观损失均随施氮量的增加而增加。氮盈余主要以土壤Nmin残留量为主,表观损失在氮盈余比例较小,但随着施氮量的增加显著增加。水稻氮吸收量、土壤无机氮残留量和氮素表观损失量与施氮量呈显著的正向相关性。在本试验条件下,综合水稻产量、氮肥利用效率和土壤无机氮积累等方面的因素,在吉林省水稻主产区,适宜施氮量应控制在180~204 kg hm~(-2)范围内。     

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。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。