氮、磷、钾及其配施对制种玉米养分吸收利用的影响

采用随机区组试验,设不施肥(CK)、缺氮(PK, P_2O_5∶K20=138∶72)、缺磷(NK, N∶K_20=448.5∶72)、缺钾(NP, N∶P_2O_5=448.5∶138)、氮磷钾配施(N∶P_2O_5∶K_2O=448.5∶138∶72)5个处理,研究河西地区氮、磷、钾及其配施对制种玉米养分吸收、肥料利用率和产量的影响。结果表明:氮磷钾配施(NPK)对制种玉米生物量的累积有明显促进作用,增产效果显著,产量达到9 834.0 kg·hm~(-2),缺氮(PK)、缺磷(NK)、缺钾(NP)处理产量分别较氮磷钾配施(NPK)降低6.06%、10.07%和4.88%。产量的主要限制因子依次为磷、氮和钾。氮磷钾配施处理的氮、磷、钾肥料利用率分别为22.64%、26.82%和60.10%,氮、磷、钾肥农学效率分别为N 1.33 kg·kg~(-1),P_2O_5 7.17 kg·kg~(-1),K_2O 6.66 kg·kg~(-1)。因此,河西地区制种玉米生产中应重视磷、钾肥的施用,加强氮肥的节肥增效管理。     

六盘山区旱作春玉米养分投入与肥料生产效率

为了明确半干旱地区玉米生产养分投入状况及肥料生产效率,提高旱地农业资源效率,连续三年对宁夏六盘山区不同类型旱地玉米施肥及生产状况进行调查。调查结果显示:六盘山区玉米生产中的氮肥(纯N)、磷肥(P_2O_5)和钾肥(K_2O)的平均投入量分别为323.7、210.1 kg·hm~(-2)和28.6 kg·hm~(-2),氮、磷、钾比例为1∶0.64∶0.08,磷的比例偏高,而钾肥比例偏低;氮、磷肥施肥量明显偏高,分别集中在高于330 kg·hm~(-2)和高于165 kg·hm~(-2)水平的农户比例高达48.5%和70.1%,造成了浪费和环境污染,钾肥用量偏低,集中处于低于42 kg·hm~(-2)水平,样本比例高达69.3%;施肥基追比大致为6∶4,追肥主要为尿素,平均用量为121.9 kg·hm~(-2),适宜玉米生长,但施追肥量处于两个极端,大多数追肥量或者很高或者很低;调研区玉米三年平均产量为9 864 kg·hm~(-2),由于降雨不足与施肥不合理,玉米产量呈逐年递减趋势;氮肥、磷肥和钾肥的三年平均偏生产力分别为30.7、47.8 kg·kg~(-1)和391.3 kg·kg~(-1),氮肥和磷肥的偏生产力偏低。该区域玉米生产有机肥投入以牛羊粪便为主,投入量偏低。综上所述,调研区施肥方面存在投入量和比例不合理问题,需进行科学指导与调整。     

水肥供应对温室滴灌施肥番茄生长及水氮利用的影响

利用温室小区试验,以番茄"惠玉0806"为供试品种,研究了不同水肥供应对温室滴灌施肥番茄的生长、产量及水氮利用的影响。试验设3个灌水水平:高水I1(100%ET0)、中水I2(75%ET0)和低水I3(50%ET0);以及3个施肥水平:高肥F1(N 480 kg·hm~(-2)、P_2O_5240 kg·hm~(-2)、K_2O 300 kg·hm~(-2)),中肥F2(N 360 kg·hm~(-2)、P_2O_5180 kg·hm~(-2)、K_2O 225 kg·hm~(-2))和低肥F3(N 240 kg·hm~(-2)、P_2O_5120 kg·hm~(-2)、K_2O 150 kg·hm~(-2)),共9个处理。结果表明:当水肥供应模式为I2F2时,茎粗增长量、产量、干物质累积量、水分利用效率和灌溉水利用效率均最高,其值依次为10.3 mm、102 042.3 kg·hm~(-2)、37 192.3 kg·hm~(-2)、352.8 kg·mm-1·hm~(-2)和372.6 kg·mm-1,并进一步提高了其氮肥偏生产力(133.4 kg·kg~(-1)),同时使得其成熟期0~50 cm土层残留硝态氮含量较低(105.3 mg·kg~(-1))。灌水量低的处理(I3)产量降低的同时,增加了土层残留硝态氮含量;充分灌水(I1)处理较之于I2处理主要降低了水分利用率,而土壤残留硝态氮累积量无差异。从总体变化趋势看,中水中肥(I2F2)模式在高产高效的同时,可降低土壤残留硝态氮含量,可认为是基于本试验条件下较适宜的水肥组合。     

施氮量对滴灌高产春大豆根系生长及产量的影响

为揭示施氮量对滴灌高产春大豆根系生长及产量的影响规律,在田间滴灌条件下采用挖掘取样法研究了0 kg·hm~(-2)(N_0)、75 kg·hm~(-2)(N_(75))、150 kg·hm~(-2)(N_(150))、225 kg·hm~(-2)(N_(225))4种施氮量对新大豆27号0~80 cm土层根系干物质量、侧根长度、表面积、根系活性、伤流量、根瘤数、根瘤质量及产量的影响。结果表明:随着施氮量的增加,0~80 cm土层根系总干物质量、侧根总长度、侧根总表面积呈现先增后降的变化趋势,均以N_(150)处理最高,在R_5(始粒期)期分别较N_0增加27.3%、49.46%、38.14%,其中,0~20 cm土层分别较N_0增加27.0%、29.02%、34.24%;R_5期N_(150)单株伤流量较N_0增加176.0%,R_2(盛花期)期0~20、20~40 cm土层根系活力N_(150)分别较N_0增加44.3%、25.1%;R_5期N_(150)单位面积根瘤数及质量分别较N_0减少8.74%、34.6%;施氮可增加产量,以N_(150)产量最高,为4 889.62kg·hm~(-2),氮肥农学利用效率3.58 kg·kg~(-1)。施氮增加产量主要是促进0~20 cm土层根系生长,提高0~40 cm根系活力的结果。     

氮肥和密度对胡麻水分、氮素利用率及产量的影响

在大田环境下,设置氮肥(0、75、150 kg·hm~(-2))和密度(4.5、7.5、10.5×10~6粒·hm~(-2))2因素共9个处理(N_0D_1、N_0D_2、N_0D_3、N_1D_1、N_1D_2、N_1D_3、N_2D_1、N_2D_2、N_2D_3)的随机区组试验,分析了不同施氮量和种植密度组合对旱地胡麻土壤含水量、贮水量、籽粒产量及产量构成因子、水分和氮素利用率的影响。结果表明,氮肥、密度各处理土壤含水量变化主要表现在苗期～青果期0～60 cm土层,以N_1D_1处理为优,最高达到15.52%;N_2D_1处理0～200 cm土壤平均含水量为18.25%,其生育季内0～200 cm土壤贮水量亦较最低处理N_1D_3增加4.62%,具有较好的肥水耦合优势。胡麻产量随处理中施氮量和密度增加呈先降后升趋势,随施氮量变幅为66.58～171.64 kg·hm~(-2),随密度变幅为32.42～68.47 kg·hm~(-2)。籽粒产量和水分利用效率对施氮水平呈现明显的正效应,高氮(N_2)较中氮(N_1)和不施氮(N_0)水平产量上升14.97%～16.05%,水分利用效率增加7.14%～21.75%;而增加密度对胡麻产量和水分利用效率并未有显著影响,组合中均为4.5×10~6粒·hm~(-2)处理下最高,分别达到1 802.00 kg·hm~(-2)和7.87 kg·hm~(-2)·mm~(-1)。增施氮肥显著提高了植株氮素吸收量,高氮(N_2)、中氮(N_1)较不施氮(N_0)分别显著增加82.21%和57.55%;平均氮素吸收利用率则均随施氮量和密度上升而降低,高氮(N_2)较中氮(N_1)水平显著降低42%,高密度(D_3)、中密度(D_2)平均氮素利用率分别较低密度(D_1)处理显著降低58.45%和35.19%。在试验处理区间内,高氮配合增密不利于提高氮素吸收利用率, N_1D_1组合氮素利用率最优,为64.3%。氮肥密度互作后,籽粒产量与有效分茎数间(0.688~*)、有效分枝数与单株有效果数间(0.877~*)均显著相关,且分茎数、分枝数受密度影响程度大于施氮量,而千粒重受限于施氮量更甚,不同施氮水平间变幅达到0.04～0.29 g。因此,氮肥密度互作时,增密对水分利用效率及产量无显著影响,适量氮肥施用可促进胡麻生育前、中期水分有效利用和提高氮素利用率,使胡麻产量及水分利用效率显著增加。在本试验及相似农田生态类型环境下,兼顾节本增效和环境安全,施氮量75～150 kg·hm~(-2)、种植密度4.5×10~6粒·hm~(-2)可作为黄土高原干旱半干旱区胡麻高效生产的适宜参考氮肥密度组合。     

陇东旱塬区小麦配方施肥效应研究

本研究目的在于探讨配方施肥与常规施肥对小麦生产肥料利用的影响,为合理使用化肥提供技术依据。采用田间随机区组试验,通过配方N 187.5 kg·hm~(-2),P 90.0 kg·hm~(-2),K 60.0 kg·hm~(-2)、N 187.59 kg·hm~(-2),P 90.0 kg·hm~(-2)、N 187.5 kg·hm~(-2),K 60.0 kg·hm~(-2)、P 90.0 kg·hm~(-2),K 60.0 kg·hm~(-2)和常规N 157.5kg·hm~(-2),P 88.5 kg·hm~(-2),K 88.5 kg·hm~(-2)、N 157.5 kg·hm~(-2),P 88.5 kg·hm~(-2)、N 157.5 kg·hm~(-2)、K 88.5 kg·hm~(-2)、P 88.5 kg·hm~(-2),K 88.5 kg·hm~(-2)施肥量的比较,研究氮、磷、钾肥料利用率及对产量的影响。结果表明:地膜覆盖栽培条件下,配方施肥比常规施肥小麦平均增产537.75 kg·hm~(-2),增产7.31%。肥料利用率提高12.51%(其中氮肥提高2.4%,磷肥提高2.17%,钾肥提高7.94%)。结论:在陇东旱塬瘠薄肥力区生产水平下,配方比例N∶P∶K为12.5∶6∶4,采用地膜覆盖栽培,测土配方施肥小麦的氮肥利用率为37.4%,磷肥利用率为24.1%,钾肥利用率为43.0%。常规施肥小麦的氮肥利用率为35.0%,磷肥利用率为21.9%,钾肥利用率为35.1%。配方施肥与常规施肥相比,具有显著的增产效果,能显著提高肥料利用率,应大力推广应用。     

日光温室钾镁配施对土壤固相和液相钾、钙、镁分配及比例的影响

针对西北地区日光温室作物出现的缺镁问题,通过施用不同水平的硫酸镁肥及减少钾肥施用处理,探究钾、钙、镁离子在土壤固相和液相的分布及比例。得出以下结论:土壤液相镁浓度随着镁肥施用量的增加而显著增加,施用45 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理和施用90 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理镁浓度相比不施用MgSO_4处理分别增加26.64%、74.78%;相比不施用MgSO_4处理,施用镁肥后土壤液相Mg~(2+)占K~+、Ca~(2+)、Mg~(2+)总量的比例显著增加,施用45 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理、施用90 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理和施用90 kg·hm~(-2)MgSO_4(200 kg·hm~(-2)K_2O)处理分别增加32.03%、31.62%、32.84%;施用镁肥促进钾由固相向液相转移;相比不施用MgSO_4处理,施用45、90 kg·hm~(-2)MgSO_4处理土壤固相交换性钾含量分别降低15.78%、27.74%,差异达到显著水平;交换性钾饱和度分别降低13.39%、27.21%;液相钾浓度显著增加,分别增加18.84%、73.91%;K+占K+、Ca~(2+)、Mg~(2+)总量的比例显著增加,增幅分别为23.91%、31.21%;土壤固相K+/Mg~(2+)比例分别降低14.52%、26.61%,;土壤液相Ca~(2+)/Mg~(2+)比例显著降低,降幅分别为31.51%、32.29%;施用MgSO_4肥量相同,钾肥施用量减半,土壤液相钾浓度降低69.88%,K+/Mg~(2+)比例降低20.88%;施用镁肥对番茄具有一定的增产作用,并能促进作物对镁的吸收。     

滴灌水氮运筹对南疆春小麦根系生长及产量的影响

以南疆地区春小麦新春6号为供试材料,采用土柱栽培法,通过滴灌开展水、氮两因素控制性试验,滴施纯氮量设N_0(不施氮肥)、N_1(69 kg·hm~(-2))、N_2(172.5 kg·hm~(-2))和N_3(276 kg·hm~(-2))4个水平,滴灌水量设W_1(2 250 m~3·hm~(-2))、W_2(3 000 m~3·hm~(-2))、W_3(3 750 m~3·hm~(-2))和W_4(4 500 m~3·hm~(-2))4个水平,共16个水氮组合处理。结果表明:扬花期是滴灌春小麦根系生长的高峰期,有64.52%～76.90%的根系干质量和76.39%～82.47%的根长分布在0～40 cm土层中。适当增施水氮能有效促进根系生长并提高产量,其中扬花期N_3W_3、N_2W_3、N_3W_2处理的根干质量、根干质量密度、根长、根长密度、根系直径和根系表面积较高,分别为123.0～148.3 mg、97.07～117.03 g·m~(-3)、14 405.8～16 490.8 mm、1.14～1.30 cm·cm~(-3)、0.3267～0.3365 mm和14 245～17 624 mm~2,其产量也达到8 695.7～9 966.1 kg·hm~(-2)的较高水平。N_3W_4处理的根系各项指标虽然较高,但蜡熟期下降过快,表明水氮过高对延缓根系衰亡不利。水氮对根系生长及产量具有显著的互作效应,且水分效应高于氮素效应。通过分析,本地区较适宜的水、氮供应范围分别为3 750～4 500 m~3·hm~(-2)和172.5～276 kg·hm~(-2),当施氮量259.4 kg·hm~(-2)、滴灌量3 793.4 m~3·hm~(-2)时产量可达最高为9 142.9 kg·hm~(-2)。     

施肥对甜瓜风味物质的影响

以新疆主栽甜瓜品种"黄皮9818"为试材,在设施栽培条件下研究不同施肥处理(NPK:施氮、磷、钾;N_0:缺氮;P_0:缺磷;K_0:缺钾;CK:不施肥)对新疆甜瓜风味物质组成及含量的影响。结果表明:不同施肥条件下,甜瓜芳香物质的种类和含量有一定差异,以2015年数据为例,5个施肥处理共检测出60种芳香物质,主要由酯类、醇类、醛类、酮类和其他物质构成,N_0和CK处理所检出芳香物质较少,分别为36种和37种;在芳香物质含量上,各处理酯类和醇类物质所占比重最大,其次为醛类物质,其中NPK处理酯类物质含量最高,达50%以上,其次为P_0、K_0处理。甜瓜折光糖、Vc和总糖含量在NPK处理下分别较N_0、K_0和CK处理增加0.51%～2.47%、0.57～19.06 mg·100g~(-1)和1.14%～4.10%。     

减量分施钾肥对旱地马铃薯产量和钾肥利用率的影响

在云南省会泽县高、低肥力土壤上分别开展旱作马铃薯的钾肥减量分施试验,研究100%、90%、70%钾肥一次性施用,90%和70%钾肥不同比例分次施用对马铃薯产量、经济效益、钾肥利用率、钾肥农学效率和钾肥偏生产力的影响。结果显示:钾肥对马铃薯生长影响较大,施钾处理的产量比无钾处理高17.39%~42.88%,施钾处理的净收益比无钾处理高15.40%~40.92%;同一处理的马铃薯产量、效益、钾肥利用率、钾肥农学效率和钾肥偏生产力等在高肥力土壤上均优于其在低肥力土壤上。无论在高、低肥力土壤上,施用钾肥量相同时,钾肥后期多施的90%K(30%+60%)处理和70%K(20%+50%)处理产量高于钾肥分次施用的90%K(40%+50%)处理和70%K(30%+40%)处理,钾肥分次施用的90%K(40%+50%)处理和70%K(30%+40%)处理产量均高于钾肥一次性施用的90%K处理和70%K处理。高肥力土壤上,100%K处理马铃薯产量为29 544.44 kg·hm~(-2),是所有处理中最高的,90%K(30%+60%)处理产量为28 770.83 kg·hm~(-2),与100%K处理没有显著性差异,钾肥利用率、钾肥农学效率和钾肥偏生产力最高的是70%K(20%+50%)处理,分别为36.84%、58.11 kg·kg~(-1)和222.22 kg·kg~(-1)。低肥力土壤上,钾肥施用时期后移的90%K(30%+60%)处理和70%K(20%+50%)处理产量、钾肥利用率、钾肥农学效率和钾肥偏生产力均高于100%K处理;90%K(30%+60%)处理产量、钾肥利用率、钾肥农学效率和钾肥偏生产力分别为17 640.28 kg·hm~(-2)、20.24%、31.13 kg·kg~(-1)和108.89 kg·kg~(-1),70%K(20%+50%)处理分别为17 404.17 kg·hm~(-2)、26.57%、38.15 kg·kg~(-1)和138.13 kg·kg~(-1),100%K处理分别为17 091.67 kg·hm~(-2)、17.49%、24.97 kg·kg~(-1)和94.95 kg·kg~(-1)。钾肥减量分施效果优于钾肥一次性施用,减量分施钾肥在低肥力土壤上的效果比高肥力土壤上的效果显著。高肥力土壤上推荐施用K_2O总量162 kg·hm~(-2),低肥力土壤上推荐施用K_2O总量126~162 kg·hm~(-2),两种肥力土壤上施用比例均为苗期30%、现蕾期70%。     

Mercury, arsenic, and cadmium in fish, water, and sediment of American Falls Reservoir, Idaho, 1974.

Mercury and cadmium were found in fish, water, and sediment of American Falls Reservoir (AFR), Idaho. Mercury and cadmium levels in some fish exceeded human health standards set by the Food and Drug Administration, U.S. Department of Health, Education and Welfare, and the World Health Organization. Analyses performed on the flesh of rainbow trout showed mercury residues of up to 1.20 mg/kg, which were higher than residues previously reported in trout collected in 1970 and 1971 from AFR. Cadmium residue levels were as high as 0.80 mg/kg. Although arsenic was found in reservoir sediment at levels of 1.36-2.40 mg/kg, it was not detected in fish.     

Intestinal uptake,metabolism, and transport of naphthol: In vitro capacity,requirements, and inhibition

The metabolism and transport of [¹⁴C]-naphthol were investigated in sacs of rat small intestine to better understand metabolism of the pesticide carbaryl (which contains naphthol) in the intestine. The capacity to synthesize polar ¹⁴C-labeled metabolites was approximately saturated at 50 μM naphthol. The metabolic capacity of the cranial small intestine was about two times the capacity of the caudal. Anaerobic incubation severely suppressed naphthol metabolism. Sodiumfree medium suppressed metabolism only slightly but altered transport of water and of the polar ¹⁴C-labeled metabolites to serosal and mucosal fluids; the effect on metabolite transport cannot be explained by the effects of sodium on water movements, however. Calcium-free medium did not affect metabolism or metabolite transport; 2,4-dinitrophenol, and possibly phlorizin, but not ouabain, suppressed naphthol metabolism in specific regions of the intestine. Each of the three inhibitors altered metabolite transport. It is concluded that the capacity to conjugate naphthol in the small intestine is greater in the cranial than caudal regions; the quantity of naphthol taken up from the medium is proportional to the rate of formation of the polar metabolite, naphthyl glucuronide; addition of 2,4-dinitrophenol, phlorizin, or ouabain, or deletion of sodium, perturbed the transport of the polar metabolite, but the perturbance could not be explained by the effect on rate or direction of fluid transfer and indicated an effect on cellular permeability or on transport mechanisms; the effect of the three inhibitors and possibly of elevated naphthol concentrations (to 520 μM) in the medium on metabolite transport may be by a sodium interaction; the latter suggests that naphthol may be toxic to the intestine at concentrations approaching 100 to 1000 μM.     

Insecticidal activity of N,N-diethyl-, N,N-dipropyl-, N,n-di-isopropyl-, and n,n-di-isobutylalkanamides against mosquito larvae

N,N-Diethyl-, N,N-dipropyl-, N,N-di-isopropyl, and N,N-di-isobutylalkanamides in which the acyl moiety ranged from C₈ to C₂₁ were synthesised, and their larvicidal activity was determined against the first-instar larvae of the southern house mosquito Culex quinquefasciatus Say. The four homologous series of amides generally showed an increase in their larvicidal activity as the carbon number in the acyl moiety of the amides increased, until the activity reached a maximum. Subsequently, an increment of carbon number resulted in declining activity in the higher homologues, until the activity disappeared. N,N-Diethyltetradecanamide, N,N-dipropylundecanamide, N,N-di-isopropylundecanamide, and N,N-di-isobutlynonanamide or -dodecanamide were the most active compounds in their respective homologous series of amides; however, they were less active than their analogous N,N-dimethylalkanamides previously studied.     

Population dynamics of Rhizoctonia,Oculimacula, and Microdochium species in soil,roots, and stems of English wheat crops

This study aimed to elucidate the population dynamics of Rhizoctonia, Oculimacula, and Microdochium species, causing the stem base disease complex of sharp eyespot, eyespot, and brown foot rot in cereals. Pathogen DNA in soil, roots, and stem fractions, and disease expression were quantified in 102 English wheat fields in two seasons. Weather data for each site was collected to determine patterns that correlate with assessed diseases. Oculimacula spp. (66%) and R. solani AG 2-1 (63%) were most frequently detected in soil, followed by R. cerealis (54%) and Microdochium spp. (33%). Oculimacula spp. (89%) and R. cerealis (56%) predominated on roots and soil but were not associated with root rot symptoms, suggesting that these species used soil and roots for survival and as inoculum source. M. nivale was more frequently detected than M. majus on stems up to GS 21–30 and co-occurred on plant samples with O. acuformis. O. yallundae had higher DNA concentration than O. acuformis at the lower 5 cm basal region at GS 37–45. R. cerealis predominated in the upper 15 cm above the base beyond stem extension. Brown foot rot by Microdochium spp. was favoured by cool and wet autumns/winters and dominated in English wheat. Eyespot and sharp eyespot disease index by Oculimacula spp. and R. cerealis, respectively, correlated with wet/humid springs and summers. Results suggested that stem base pathogens generally coexisted; however, their abundance in time and space was influenced by favourable weather patterns and host development, with niche differentiation after stem extension.     

DDT and BHC residues in some body tissues of goats, buffalo, and chickens, Lucknow, India

Muscle, liver, brain, and abdominal body fat samples of goats, buffalo, and chickens, all common meat sources in India, were analyzed by gas-liquid chromatography (GLC) for residues of DDT and benzene hexachloride (BHC). A few samples of goat and buffalo bone marrow were also included. Relatively high residue levels were found in body fat and bone marrow compared with other tissues. DDT and BHC residue levels were highest in chicken body fat, averaging 4.157 ppm sigma DDT and 3.879 ppm BHC. DDT content was much higher in goat and buffalo bone marrow than in the corresponding body fat. DDT levels in brain samples were highest (0.138 ppm) in buffalo. p,p'-TDE levels were higher than p,p'-DDE levels in buffalo; overall DDT levels were lowest in goats. BHC residues were generally low in buffalo; alpha-BHC accounted for most BHC residues in brain tissues. Greater accumulations of DDT and BHC were found in leg muscles than in breast muscles of chickens.     

啶酰菌胺在南瓜、芦笋、山楂、芒果和木瓜上的膳食摄入风险评估

为明确啶酰菌胺在南瓜、芦笋、山楂、芒果和木瓜上使用可能产生的膳食摄入风险,通过进行规范田间残留试验,检测了南瓜、芦笋、山楂、芒果和木瓜中啶酰菌胺的最终残留量,结合国内和国际两种膳食消费量数据,评估了啶酰菌胺的长期膳食摄入风险,并就两种方法的评估结果进行了比较分析。样品采用QuEChERS方法前处理,液相色谱-串联质谱 (LC-MS/MS) 定量分析。结果表明:南瓜在0.01、0.1和3 mg/kg,芦笋在0.01、0.1和20 mg/kg,山楂在0.01、0.1和60 mg/kg,芒果在0.01、0.1和4 mg/kg,木瓜在0.01、0.1和10 mg/kg添加水平下,啶酰菌胺在空白样品中的平均回收率为79%~101%,相对标准偏差为2%~14%。采用 “中国居民营养与健康状况调查报告” 的膳食消费数据,计算得啶酰菌胺针对普通人群的国家估算每日摄入量 (NEDI) 为0.707 5 mg/(kg bw),风险商 (RQ) 为28.1%;采用世界卫生组织 (WHO) 提供的每种农产品的单独膳食量进行计算,啶酰菌胺的每日摄入量为0.128 2 mg/(kg bw),风险商 (RQ) 为5.1%。两种方法的评估结果均表明啶酰菌胺对一般人群的健康不会产生不可接受的风险,然而,采用不同膳食消费数据进行计算会导致风险评估结果存在较大差异,其原因主要是由于中国所采用的膳食消费数据是作物分类基础上的数据,而不是具体某种农产品的单独消费量,因而易导致中国的膳食摄入风险评估结果过于保守。因此建议相关部门进一步完善居民的营养与健康状况调查监测工作,提供具体到每一种农产品的膳食消费数据,以便于科学评价农药对人体健康的风险。     

施肥对小麦、玉米和大豆连作土壤微生物群落功能多样性的影响

为了明确长期施肥和不施肥条件下作物连作对土壤微生物群落功能多样性的影响,以典型黑土为研究对象,选取长期定位实验站长期施肥和不施肥条件下的小麦、玉米和大豆连作处理,通过稀释平板法和Biolog Eco微平板法,测定土壤细菌、真菌、放线菌数量、碳源代谢活性等指标,为建立合理的农田管理措施提供数据支撑和理论依据。结果表明:长期施肥条件下大豆、小麦和玉米连作土壤细菌、真菌和放线菌数量均高于不施肥处理,且均以大豆连作处理细菌和真菌数量最高。不施肥条件下小麦和玉米连作土壤细菌总数较大豆连作处理分别下降了24.8%和31.0%,真菌总数分别下降了64.0%和51.2%;施肥条件下小麦和玉米连作土壤细菌总数则较大豆连作处理分别下降了29.0%和45.5%,真菌总数分别下降了26.7%和31.5%。Biolog结果表明,不施肥条件下小麦连作处理的平均颜色变化率(AWCD)高于玉米和大豆连作处理,施肥条件下则是大豆连作处理的AWCD值高于小麦和玉米连作处理。不施肥条件下大豆、玉米和小麦连作处理利用最多的碳源是碳水化合物类,施肥后不同连作处理利用最多的是碳水化合物类和多聚物类。大豆和小麦连作不施肥条件下土壤微生物利用率最高的碳源均是α-D-乳糖,施肥条件下利用率最高的碳源均是D,L-α-甘油,而不论施肥与否,玉米连作条件下土壤微生物利用率最高的碳源均是D-半乳糖醛酸;葡萄糖-1-磷酸盐和γ-羟基丁酸是农田黑土微生物群落特异利用的关键碳源。主成分分析得出,施肥对土壤微生物碳源代谢能力的影响大于作物的影响。     

Comparison of trifluralin,oryzalin, pronamide,propham, and colchicine treatments on microtubules

The mode of action of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), oryzalin (3,5-dinitro-N⁴,N⁴-dipropylsulfanilamide), pronamide(N-(1,1-dimethylpropynyl) 3,5-dichlorobenzamide), and propham (isopropyl carbanilate) on purified microtubules from pig brains and on the ultrastructure of wheat (Triticum aestivum L. “Mediterranean,” C. I. 5303) and corn (Zea mays L. “yellow dent, U. S. 13”) roots was compared with that known for colchicine. Colchicine disrupts the in vivo cortical and spindle microtubules of root cells. Like colchicine, the herbicides trifluralin, oryzalin, and pronamide caused the loss of both cortical and spindle microtubules of root cells. The rate of microtubule disappearance depended on the type of herbicide and length of exposure of roots to the herbicide. Unlike colchicine, cortical microtubules were present in propham-treated roots but they were disoriented within the cell.In vitro polymerization studies with pig brain microtubules (Sus scrofa) showed that the herbicides failed to inhibit the assembly of purified microtubular protein into microtubules and that radioactively labeled herbicides did not bind to the microtubular protein. Colchicine inhibited the polymerization of microtubular protein and readily bound to the microtubular subunits. These results indicate that the mode of action of the herbicides is not similar to that of colchicine and that the loss of microtubules from root tip cells treated with trifluralin, oryzalin, and pronamide may be caused by these herbicides interfering with synthesis of microtubular protein or metabolism of endoplasmic reticulum membranes involved in microtubule assembly. The mode of action of propham appears to be on the microtubular organizing centers rather than on microtubules per se.     

Action of some herbicides on growth,respiration, plasmalemma integrity,and proton extrusion of Acer pseudoplatanus cells: II. Amides,diphenyl ethers,nitriles, phenols,triazines, and uracils

The activity of 15 herbicides from different families was assayed on nonphotosynthetic Acer pseudoplatanus cells, in batch suspension culture. They inhibited growth, stimulated the oxygen consumption by cells, and changed the pH evolution of the culture medium. Amides did not seem to disturb the membrane properties. Some diphenyl ethers and phenols directly modified the proton compartmentation of cells whereas some other diphenyl ethers, nitriles, triazines, and uracils altered permeabilities to potassium and leucine. Changes in membrane permeabilities to protons and medium constituents were discussed.