DTA-6、SODM及Cc对马铃薯地下主茎生长及同化物代谢生理的影响

大田栽培条件下,以马铃薯荷兰212为材料,叶面喷施植物生长物质2-N,N-二乙氨基乙基己酸酯（Diethyl aminoethyl hexanoate,简称DTA-6）、氯化胆碱（Choline chloride, 简称Cc）以及SOD模拟物(简称SOD_M),测定地下主茎鲜重、干重、蔗糖、蔗糖转化酶活性、淀粉、淀粉酶活性变化以及可溶性糖等含量的变化,研究不同植物生长物质对马铃薯地下主茎生长及碳代谢生理指标的影响。结果表明：从喷药后16 d开始,Cc和SOD_M处理均能大幅提高地下主茎蔗糖的含量,其中Cc处理平均比CK增加36.68%,SOD_M处理较CK高出30.36%。同时喷施Cc后40 d和48 d淀粉酶活性提高,平均增幅为35.11%。从喷药后32 d开始,DTA-6和Cc处理对转化酶活性也具有提高的效应,DTA-6处理平均提高了35.75%,Cc处理平均提高了34.79%,但方差分析结果表明差异不显著。另外SOD_M处理能够极显著降低块茎膨大时期地下主茎内淀粉含量,而Cc处理可极显著提高此时期地下主茎的可溶性糖含量。     

植物生长调节剂对大豆叶片碳代谢相关生理指标的影响

在大田栽培条件下,以垦农4号大豆为材料,通过叶面喷施植物生长调节剂,比较叶片中蔗糖、转化酶、淀粉、可溶性糖、还原糖和总糖含量及转化酶活性,研究6-苄基腺嘌呤(6-BA)、脱落酸(ABA)对大豆叶片碳代谢相关生理指标的影响.结果表明:6-BA、ABA两处理在喷药后40天均提高了大豆叶片中蔗糖含量,除喷药后40d的取样期内...     

干旱与复水对马铃薯块茎膨大期碳氮转运的影响

为探讨干旱及复水对马铃薯块茎膨大期碳氮物质转运影响的生理机制,采用盆栽控水法研究了干旱胁迫、旱后复水过程中马铃薯叶片与块茎中碳水化合物、氮素同化物以及碳氮转运相关酶活性的变化规律。结果表明：干旱胁迫下马铃薯叶片蔗糖磷酸合成酶（SPS）活性显著增强,增幅为54.9%,可溶性糖与蔗糖含量显著增加,分别增加84%、25%;块茎蔗糖与淀粉含量显著下降,分别降低25%、11.8%。复水后叶片可溶性糖含量变化较小,叶片SPS活性仍保持较高水平;块茎中蔗糖合成酶（SS）活性下降6.25%(P＜0.05),蔗糖与淀粉含量分别增加21.8%、29.8%。干旱胁迫下马铃薯叶片中硝酸还原酶（NR）活性下降49.3%,谷氨酰胺合成酶（GS）活性与对照差异不显著,叶片游离氨基酸与可溶性蛋白质含量分别降低29.4%、38.4%,全氮含量降低13%;块茎中游离氨基酸与可溶性蛋白质含量增加16.8%、270.9%。复水后叶片中NR与GS活性高出对照3.5%、12.1%,叶片游离氨基酸、可溶性蛋白质以及全氮含量仍保持较低水平;块茎游离氨基酸、可溶性蛋白含量较高,增幅分别为24.6%、178.4%,全氮含量增加,与对照差异不显著。说明干旱胁迫显著阻碍了马铃薯碳水化合物与氮素同化物的合成与转运,使马铃薯叶片碳水化合物积累,但干旱促进了氮素向块茎转运,块茎中的碳氮比下降;复水后马铃薯植株能够快速修复干旱胁迫造成的损伤,表现为块茎中淀粉含量增多,块茎碳氮比增加。     

植物生长调节剂对马铃薯叶片生理代谢及产量品质的影响

大田栽培条件下,以马铃薯克新13为材料,叶面喷施植物生长调节剂2-N,N-二乙氨基乙基己酸酯(Diethyl aminoethyl hexanoate,简称DTA-6)、缩节安(Mepiquat chloride,简称DPC)以及烯效唑(Uniconazole,简称S3307),研究植物生长调节剂对马铃薯叶片生理代谢及产量、品质形成的影响。结果表明:在马铃薯块茎膨大期喷施植物生长调节剂,均显著增加了单薯重、淀粉产量和鲜薯产量,其中,以DTA-6调控效果为最佳,单薯重、淀粉产量、鲜薯产量和淀粉含量比CK分别增加了10.40%、40.26%、26.56%和11.32%,块茎还原糖含量比CK降低了20%。此外,调节剂处理均提高了马铃薯叶片叶绿素含量、净光合速率、蒸腾速率和细胞间隙CO_2浓度,加快了叶片的光合作用,各指标与产量之间呈正相关。随着时间的推移,各处理的叶片淀粉和蔗糖含量呈先降低后升高的变化趋势,淀粉酶活性呈降低的变化趋势,调节剂对叶片蔗糖转化酶活性的调控效果呈不同规律的变化。总体而言,调节剂均提高了马铃薯产量,改善了块茎品质,其中DTA-6处理效果最佳。     

叶面喷施K2SO4对‘瑞雪’苹果果实糖代谢的影响

为探究喷施不同浓度叶面钾肥对苹果品种‘瑞雪’果实品质的影响,确定最适宜‘瑞雪’的钾肥浓度,以4年生的‘瑞雪’为试验材料,叶面钾肥种类为K₂SO₄,设置3个浓度梯度分别为T1（0.1%）、T2（0.3%）和T3（0.5%）,以喷施清水为对照（CK）。叶面钾肥分5次施入,第一次施肥时间为5月22日（花后38 d）,此后每隔一个月喷施一次。各处理分别于花后45、75、105、135 d和180 d采集果实样品并测定糖组分、糖代谢相关酶活性以及果实基本品质等指标。结果表明：与对照相比,处理组（T1、T2、T3）均显著提高了‘瑞雪’果实的单果质量,分别比CK高12.6%、25.9%和4.4%;果实硬度分别比CK显著提高7.7%、29.6%和12.1%;可溶性固形物含量分别比CK显著提高了1.14、1.95和0.87个百分点;处理组均显著降低了可滴定酸含量,分别比CK降低了0.04、0.05和0.09个百分点。其中,T2处理后的果实单果质量、硬度、可溶性固形物含量最高,单果质量为335.75 g,硬度为9.82 kg·cm^-2,可溶性固形物含量为16.35%。T3处理后的果实可滴定酸含量最低,为0.19%。施钾显著提高了新梢叶片中N、P、K、Ca和Mg的含量,显著提高了果实中N、K、Ca和Mg的含量,果实中P含量并没有显著上升。T2处理后成熟果实中果糖、蔗糖和葡萄糖含量显著上升,与CK相比分别提高了35.54%、33.22%、25.31%。钾可以提高果实中酸性转化酶（AI）、山梨醇氧化酶（SOX）、山梨醇脱氢酶（SDH）和蔗糖合酶（SS）的活性,在花后180 d时,T2处理 AI、SOX、SDH、SS活性相比于CK分别提升了4.54%、2.08%、19.11%、12.81%。相关分析表明,施钾与果实中葡萄糖含量在花后45 d和75 d具有极显著正相关性（r_45DAB=0.879^**、r_75DAB=0.893^**）;与山梨醇含量在花后180 d具有极显著负相关性（r_180DAB=-0.861^**）。施钾与果实中的中性转化酶活性在花后135 d具有极显著正相关性（r_135DAB=0.763^**）;与山梨醇氧化酶活性在花后45 d和75 d具有极显著正相关性（r_45DAB=0.717^**,r_75DAB=0.880^**）;与蔗糖合酶在花后180 d具有极显著正相关性（r_180DAB=0.739^**）。最适宜‘瑞雪’苹果喷施K₂SO₄叶面肥的浓度水平为0.3%（T2）,此浓度下可以显著提高果实产量和品质。     

PP333对干旱胁迫下马铃薯幼苗抗旱性及块茎营养的影响

探讨了干旱胁迫下叶面喷施多效唑(PP333)对马铃薯幼苗抗旱生理及块茎营养的影响,结果表明在幼苗的生长发育方面,干旱胁迫下叶面喷施PP333相对降低了植株的株高、单株结薯数和地上部分的生物量,增加茎粗和薯均重,显著提高叶片脯氨酸和可溶性糖含量,使干旱胁迫下叶片含水量和叶绿素含量下降幅度减小,显著提高SOD活性,抑制叶片相对电导率和MDA含量升高的幅度;叶面喷施PP333还显著提高了马铃薯幼苗对极端干旱的适应能力.在块茎营养方面,干旱胁迫下叶面喷施PP333提高了块茎中淀粉、蛋白质、还原糖、维生素C及干物质含量.可见PP333能显著提高马铃薯幼苗的抗旱性和块茎营养.     

干旱胁迫下外源硫化氢对芸豆苗期光合与生理特性的影响

为研究外源硫化氢（H₂S）对干旱胁迫下芸豆苗期光合与生理特性的影响,以奶花芸豆2242为试验材料,采用盆栽称重法控水进行干旱胁迫,以正常供水为对照,将硫氢化钠（NaHS）作为H₂S供体进行5种浓度喷施试验。结果表明：与对照相比,干旱胁迫降低了芸豆叶片净光合速率（P_n）、蒸腾速率（T_r）、气孔导度（G_s）和胞间CO₂浓度（C_i）,降幅为48.79%~63.72%;提升了植株体内超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和抗坏血酸过氧化物酶（APX）等抗氧化酶活性,增幅为22.00%~78.28%;提高了超氧阴离子（O^-₂）、过氧化氢（H₂O₂）、丙二醛（MDA）含量和相对电导率（REC）,增幅为91.11%~185.47%;增加了游离脯氨酸（Pro）和可溶性糖（SS）等渗透调节物质的含量,增幅为30.98%~55.55%。随复水天数增加,各类指标值不同程度增加。施用外源NaHS后,与MD处理（干旱胁迫+喷施0 mmol·L^-1外源NaHS溶液）相比,芸豆叶片光合效率、抗氧化酶活性、渗透调节物质含量均表现为先升后降,浓度为0.2 mmol·L^-1时增幅最大,分别为39.18%~89.69%、28.40%~94.63%和15.03%~86.12%;膜脂过氧化程度表现为先降后升,0.2 mmol·L^-1浓度时降幅最大,为19.91%~48.37%。相关分析表明,同类特性各指标间均呈极显著正相关关系,且相关系数表现为抗氧化酶活性>光合效率、膜脂过氧化指标>渗透调节物质含量;不同类特性间,抗氧化酶活性和渗透调节物质含量之间正相关性最强。综上可知,外源H₂S可以缓解干旱胁迫对芸豆苗期光合与生理特性的不利影响,减轻植株受到的伤害,增强其抵御干旱的能力。NaHS溶液喷施浓度为0.2 mmol·L^-1时缓解芸豆苗期干旱胁迫的效果最佳。     

干旱胁迫对赤芍生理特性影响及相关基因的克隆表达

为探究不同干旱程度对赤芍生长发育的影响及其抗旱机制,采用盆栽控水法,设置对照组、轻度干旱和重度干旱3个处理,测定赤芍叶片相对含水量、可溶性糖、可溶性蛋白、脱落酸、叶绿素、类胡萝卜素、类黄酮、丙二醛、游离脯氨酸含量、光合参数及超氧化物酶活性等生理指标,评价赤芍抗旱性;采用RT-PCR结合RACE技术克隆抗旱相关基因（DREB、Psb27、PsaK、MDHAR、SOD和GR）,探究不同干旱程度对赤芍相关基因表达水平的影响。结果表明,重度干旱胁迫下,赤芍可溶性糖、可溶性蛋白、类胡萝卜素、类黄酮、脯氨酸、丙二醛、抗坏血酸及谷胱甘肽的含量均呈上升趋势,如在重度干旱和轻度干旱24 d后,赤芍叶片可溶性糖含量分别为对照的2.50倍和1.66倍,重度干旱胁迫第16天时,可溶性蛋白含量为对照组的2.43倍,类胡萝卜素与类黄酮的含量分别约为对照组的1.8倍和1.4倍,约为轻度干旱的1.4倍和1.2倍;而叶片相对含水量、蒸腾速率、气孔导度、净光合速率与叶绿素含量均降低,如重度干旱胁迫下赤芍叶片含水量不足20%,而轻度干旱和对照组叶片含水量均高于55%,叶绿素含量在第16天降到最低值,约为对照组的26%,为轻度干旱的33%;干旱胁迫下,光合作用相关基因Psb27、PsaK的表达量上调,且重度干旱上调水平更高;多个抗氧化基因的表达量（SOD、GR）、ABA含量以及胞间CO₂浓度呈先升后降趋势,如SOD在重度干旱第16天表达水平达到峰值,分别为轻度干旱与对照组的1.58倍和1.86倍,而后剧烈下降,到第24天时表达水平降到对照组的1.43倍,其中MDHAR的表达量呈下降趋势,重度干旱第24天时表达水平降到对照组的5.53倍。     

植物生长调节剂对马铃薯块茎淀粉含量及品质的影响

大田栽培条件下,以马铃薯(Solanum tuberosum L.)荷兰212为材料,叶面喷施不同植物生长调节剂,通过比较块茎中转化酶、淀粉酶活性变化以及蔗糖、淀粉、维生素C等含量变化的差异,研究喷施植物生长调节剂对马铃薯块茎品质的调控效应.结果表明:在块茎生长过程中,2-N,N-二乙氨基乙基己酸酯(DTA-6)对块茎...     

水分亏缺对小麦芒和旗叶光合特性及蔗糖、淀粉合成的影响

为明确水分亏缺对小麦芒和旗叶光合特性及蔗糖、淀粉合成的影响,选用盆栽试验,在小麦灌浆期对盆栽采用正常供水（CK）及水分亏缺（WD）处理,测定旗叶和芒光合参数、相对水分含量、叶绿素含量等生理指标,分析蔗糖和淀粉合成关键酶活性及相关基因表达水平。结果表明,水分亏缺下旗叶净光合速率（P_n）、叶绿素（Chl）含量和相对水分含量（RWC）相比芒显著下降,花后24 d旗叶和芒P_n分别下降了87.7%和14.4%,Chl含量分别下降了54.1%和12.3%,RWC分别下降了13.9%和1.5%;同时,水分亏缺减少了光合碳同化物的产生,花后24 d旗叶和芒中蔗糖含量分别下降了50.1%和18.2%,淀粉含量分别下降了46.4%和18%,表明芒中碳同化物合成受水分亏缺影响较旗叶小。灌浆过程中旗叶和芒中丙二醛（MDA）含量均持续上升,水分亏缺下花后24 d旗叶和芒中MDA含量分别增加了50.8%和14.0%,表明在逆境下芒的抗氧化能力优于旗叶。总之,水分亏缺下芒具有较高的光合效率、保水性以及衰老延迟特性,并且在灌浆中后期仍有较高的蔗糖和淀粉合成能力,从而保障对小麦籽粒产量的光合贡献。     

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.     

长武旱塬不同麦玉轮作系统产量效应模拟研究

利用EPIC模型对不同麦玉轮作系统进行模拟,通过对其输出结果的分析,综合考虑产量、经济效益、干旱胁迫和氮肥生产率等因素,对不同麦玉轮作系统进行综合评价,从而比较不同麦玉轮作系统的优劣。结果表明:(1)在模拟研究期间,8种麦玉轮作系统的产量均呈波动性下降趋势,其平均值分别为4.61、4.40、4.16、4.48、4.28、4.29、4.714、.55 t/hm2。所有的麦玉轮作系统中,麦玉轮作系统"春玉米→冬小麦"的经济效益最好。(2)在模拟研究期间,麦玉轮作系统"春玉米→冬小麦→冬小麦"的冬小麦和春玉米所遭受的年均干旱胁迫日数最少(29.51d)。在干旱年份麦玉轮作系统中的冬小麦较春玉米更容易遭受干旱威胁。综合产量、经济效益、作物所遭受的干旱胁迫天数和麦玉轮作系统的氮肥生产率等因素,在长武地区适宜采用的麦玉轮作系统为春玉米→冬小麦。     

东北日光温室葡萄园水热通量特征及其对气象因子的响应

运用温室葡萄水热平衡观测资料,分析了东北日光温室葡萄的能量平衡和能量分量日变化、生育期变化以及分配规律,同时也分析了潜热通量（λET）对环境因子的响应。结果表明：水热通量各分量在整个生育期日变化总体上呈现为单峰趋势,净辐射（R_n）的峰值最大为618.75 W·m^-2,λET峰值最大为242.73 W·m^-2,感热通量（H）峰值最大为327.93 W·m^-2;在新梢生长期,白天λET较小,为34.55 W·m^-2,随着生育期推进,λET逐渐增大,在果实着色成熟期达到最大值（78.49 W·m^-2）之后减小;H在各生育期能量中均占了绝大部分;白天潜热通量占净辐射的比例（λET/R_n）在新梢生长期最小,为25.28%,在果实着色成熟期最大,为44.17%;感热通量占净辐射比例（H/R_n）整个生育期几乎都达50%以上,土壤热通量占净辐射比例（G/R_n）相对较小,变化范围为4.46~12.32 W·m^-2;在整个生育期能量比率大小依次为H/R_n>λET/R_n>G/R_n。在不同生育阶段瞬时尺度上,R_n是影响潜热变化最主要的气象因子,R²高达0.88。在日尺度上,各气象因子对潜热通量的影响在逐渐变弱,相对湿度（RH）与λET相关系数仅为0.28。但无论从瞬时尺度还是日尺度,R_n都是影响潜热通量最主要的气象因子。各气象因子对潜热通量的影响大小依次为：R_n>VPD>T_a>RH。     

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。     

Establishment of, and preliminary impact studies on, the rust, Maravalia cryptostegiae, of the invasive alien weed, Cryptostegia grandiflora in Queensland, Australia

The rust fungus Maravalia cryptostegiae , from south-west Madagascar, was introduced into Australia in 1995 as a classical biological control agent against the highly invasive rubber-vine weed Cryptostegia grandiflora , a woody climber endemic to Madagascar. The rust was released at 69 sites between 1995 and 1997 and is now established throughout the plant's exotic range in Queensland, estimated at over 40 000 km². Dispersal was low in the first 3–4 months but was virtually linear thereafter, and the rust spread over 100 km within the first year; after 3 years it was recorded 550 km away from the nearest release site. Spraying both dry and aqueous inoculum of uredinioid teliospores from the ground using mist-blowers, as well as from the air by atomizing spore suspensions, resulted in rust-induced defoliation, producing an overall reduction in fecundity and biomass of the weed. In sites with low water tables, weed growth decreased markedly, with a reduction in plant volume from 9 m⁻³ to 1 m⁻³ over a 4-year period. Both rust- and drought-induced stress combined to cause up to 75% plant mortality at some sites, and at all monitored sites, seedling recruitment was virtually nil. Improved growth of indigenous grasses amongst rubber-vine thickets has increased fuel loads and created opportunities to use fire as a component of an integrated approach to the management of this economically and ecologically damaging weed.     

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.     

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.     

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.     

Modeling the Risk of Entry, Establishment, Spread, Containment, and Economic Impact of Tilletia indica, the Cause of Karnal Bunt of Wheat, Using an Australian Context

ABSTRACT Modeling techniques were developed to quantify the probability of Tilletia indica entering and establishing in Western Australia (WA), and to simulate spread, containment, and the economic impact of the pathogen. Entry of T. indica is most likely to occur through imports of bulk grain or fertilizer (0.023 +/- 0.017 entries per year and approximately 0.009 +/- 0.009 establishments per year). Entry may also occur through straw goods, new or second-hand agricultural machinery, and on personal effects of travelers who have visited regions with infected plants. The combined probability of entry and establishment of T. indica, for all pathways of entry, is about one entry every 25 years and one establishment every 67 years. Alternatively, sensitivity analysis does show that increases in quarantine funding can reduce the probability of entry to about one entry every 50 years and less than one establishment every 100 years. T. indica is spread efficiently through contaminated farm machinery, seed and soil, rain, air currents, and animals. Depending on the rate of spread of the pathogen and the amount of resources allocated for detection, the time until first detection could range from 4 to 11 years and the economic impact could range from 8 to 24% of the total value of wheat production in WA.     

Pb、Cd胁迫对紫茎泽兰N、P、K吸收的影响

采用模拟Pb、Cd污染土壤培养法研究了紫茎泽兰在重金属Pb、Cd胁迫下植株不同部位对3种营养元素(N、P、K)吸收的影响。结果表明,紫茎泽兰各组织在Pb胁迫下对N、P的吸收总体上均保持一定的促进作用,对K则表现出一定的抑制效应;Cd胁迫下对N、P有良好的吸收,低浓度Cd促进K的吸收,高浓度则表现出抑制作用。Pb-Cd复合污染胁迫下根茎叶均对N的吸收有一定的促进作用,而对K的吸收有较强的抑制效应。这表明,紫茎泽兰在重金属Pb、Cd胁迫下可通过大量吸收N、P等元素来有效缓解重金属的毒害作用,这可能也是紫茎泽兰能适应高Pb、Cd胁迫的一种耐性机制。