硅促进水稻种子萌发及缓解幼苗砷毒性的效应研究

通过As~(Ⅲ)胁迫下水稻种子的发芽试验和幼苗毒性试验,研究了外源硅对水稻种子发芽率、幼苗生长的影响及其缓解幼苗砷毒性的效应。外源硅的2种处理方式为种子萌发时添加外源硅(Si1)和采用硅处理液浸种(Si2)。结果表明,发芽时介质中As浓度达到10 mg·L~(-1)时显著抑制水稻种子萌发(P0.05),发芽率仅为80%,但是Si1和Si2处理下发芽率则提高到97%和100%,这说明外源硅可促进砷胁迫下水稻种子萌发;砷浓度≥5 mg·L~(-1)时,Si1和Si2处理均可提高水稻的相对幼苗高度和根耐性指数,提高幅度分别为6.00%~16.8%和57.9%~77.0%、7.10%~23.5%和54.2%~61.2%,并且降低了水稻幼苗砷含量,降低幅度分别为17.8%~21.4%和31.0%~49.1%。这说明外源硅处理可促进砷胁迫下水稻幼苗的生长;不同砷浓度处理与水稻芽长、根长及幼苗干重之间存在"S"型的剂量-效应关系,且外源硅显著提高了相应的EC50,缓解了砷对水稻幼苗生长的毒性。综上所述,砷胁迫下水稻种子萌发时添加外源硅或采用硅处理液浸种均可促进水稻种子萌发和幼苗生长,并降低了幼苗砷累积和缓解砷对水稻幼苗的毒性。     

生物炭对小麦种子萌发与幼苗生长的植物毒理效应

为明确生物炭对植物的毒性效应,以石英砂+生物炭水浸提液培养方法研究不同剂量生物炭对小麦种子萌发与幼苗生长的影响。结果表明:在不同剂量(0.0、10.0、20.0、40.0、80.0、160.0 g·kg~(-1))生物炭水浸提液处理下,虽然小麦发芽率较对照组无显著性变化(P0.05),但根、芽生长表现出低剂量促进高剂量抑制,且在160.0 g·kg~(-1)时抑制率最大,分别为18.11%和22.22%。在幼苗的生长期(11 d),高剂量生物炭对幼苗根生长的抑制作用增强,160.0 g·kg~(-1)处理下抑制率显著增加至55.59%(P0.05)。此外,当生物炭剂量较低时,小麦幼苗根、叶中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活力增加;随生物炭剂量的增加,3种抗氧化酶活力降低,丙二醛(MDA)含量升高,幼苗生长出现生理损伤,表现出明显植物毒性效应。     

Al~(3+)和阳离子型表面活性剂复合污染对玉米幼苗的影响

研究了阳离子型表面活性剂十六烷基三甲基溴化铵 (CTAB)和Al3+ 共存 ,对玉米幼苗保护酶及叶绿素含量、光合速率、蒸腾速率等的影响。结果表明 :CTAB能加剧Al3+ 对玉米幼苗的毒害作用。具体表现为使幼苗超氧化物歧化酶和过氧化物酶活性升高 ,过氧化氢酶活性下降 ,超氧阴离子产生速率增大 ,脂质过氧化作用加剧 ,质膜透性上升 ,而叶绿素含量下降。当CTAB浓度在临界胶束浓度以上时 ,光合速率及蒸腾速率急剧降低     

石油污染土壤植物修复后对陆生高等植物的生态毒性

以经过5a植物修复处理后的石油污染土壤为供试土壤(柴油初始投加量分别为5 000,15 000,30 000 mg/kg),用重量法测定了土壤中残留矿物油含量,同时,以小麦(Triticum aestivum L.)为供试植物,以种子发芽及根伸长试验、早期幼苗生长试验、叶片内细胞色素P450单加氧酶(P450)含量、抗氧化酶(超氧化物歧化酶,SOD;过氧化物酶,POD)活性及脂质过氧化产物(丙二醛,MDA)含量等为指标对受试土壤进行生态毒理学综合评价.化学分析结果表明,各处理土壤中的矿物油均     

温度、水分和盐度对转基因耐草甘膦大豆种子萌发和幼苗生长的影响

为了探明转CP4-EPSPS(5-烯醇丙酮酸莽草酸-3-磷酸合成酶)基因是否会对大豆种子及幼苗的抗逆性产生影响,进而为转基因耐草甘膦大豆的环境安全评价提供科学依据,通过室内试验研究了温度、水分和盐度对转基因耐草甘膦大豆ARG、受体大豆n-ARG及我国传统栽培大豆苏豆3号种子萌发与幼苗生长的影响。结果表明:在种子萌发阶段,ARG对高温胁迫和水分胁迫的抗性显著低于n-ARG和苏豆3号;ARG对盐分胁迫的抗性与n-ARG没有显著差异,但抗性明显弱于苏豆3号。幼苗生长阶段,在温度胁迫(高温40℃,低温15℃)和水分胁迫(渍水和干旱)条件下,ARG在株高增长量和生物量方面都没有表现出优势,相反,在某些方面反而抗性更弱。例如,在轻度干旱胁迫(相对含水量55%)条件下,ARG地上部干重明显小于n-ARG。ARG对盐分胁迫的抗性也弱于n-ARG及我国传统栽培大豆苏豆3号。总之,与非转基因受体大豆n-ARG和我国传统栽培大豆苏豆3号相比,转基因耐草甘膦大豆ARG在温度、水分和盐度逆境条件下的竞争性和入侵性不强。     

两种咪唑氯盐类离子液体对水稻幼苗根部的毒性效应

按照毒性试验标准方法研究了1-癸基-3-甲基咪唑氯盐([DMIM]Cl)、1-十二烷基-3-甲基咪唑氯盐([C12MIM]Cl)对水稻幼苗生长的影响,测定了水稻根的半数抑制浓度(IC50-5d)、超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、过氧化物酶(POD)活性、水稻根部丙二醛(MDA)含量及对水稻根系的生理影响.结果表明:两种离子液体(ILs)对水稻幼苗根部生长均具有抑制作用,随着浓度的增大抑制率增加,[DMIM]Cl和[C12MIM]Cl的根长IC50-5d分别为0.10 mg·L-1和0.054 mg·L-1,水稻幼苗根部对两种ILs均有氧化应激反应,在[DMIM]Cl和[C12MIM]Cl处理下,3种抗氧化酶活性均受到严重抑制,丙二醛(MDA)含量升高,加剧了水稻幼苗根部细胞膜脂质过氧化作用.[DMIM]Cl和[C12MIM]Cl处理导致根系活力降低,根系质膜透性增大.     

花椒叶浸提液对大豆种子萌发和幼苗生长的化感作用

研究了不同浓度的花椒叶浸提液(5、10、20、40、80 g L-1)对3个大豆品种种子萌发、幼苗生长的化感作用.结果表明:花椒对大豆化感效应的总体趋势为浸提液浓度越高,对大豆生长的抑制作用越强;高于40 g L-1的浓度处理,主要形态和生化指标都表明大豆生长受到显著抑制或破坏;在小于20 g L-1的浓度范围内,化感作用能够提高低活力种子的萌发率,但降低了种子发芽指数和发芽速度,且化感作用受受体品种差异和自身种子活力的影响而表现不一致;随着化感物质浓度增高,SOD酶活显著降低,丙二醛(MDA)含量持续增高.大豆幼苗各器官或组织受花椒化感作用的影响大小依次为根生物量>地上部生物量>株高>根长.图2表3参12     

Effects of life history and reproduction on recruitment time lags in reintroductions of rare plants

Reintroductions are important components of conservation and recovery programs for rare plant species, but their long-term success rates are poorly understood. Previous reviews of plant reintroductions focused on short-term (e.g., ≤3 years) survival and flowering of founder individuals rather than on benchmarks of intergenerational persistence, such as seedling recruitment. However, short-term metrics may obscure outcomes because the unique demographic properties of reintroductions, including small size and unstable stage structure, could create lags in population growth. We used time-to-event analysis on a database of unusually well-monitored and long-term (4–28 years) reintroductions of 27 rare plant species to test whether life-history traits and population characteristics of reintroductions create time-lagged responses in seedling recruitment (i.e., recruitment time lags [RTLs]), an important benchmark of success and indicator of persistence in reintroduced populations. Recruitment time lags were highly variable among reintroductions, ranging from <1 to 17 years after installation. Recruitment patterns matched predictions from life-history theory with short-lived species (fast species) exhibiting consistently shorter and less variable RTLs than long-lived species (slow species). Long RTLs occurred in long-lived herbs, especially in grasslands, whereas short RTLs occurred in short-lived subtropical woody plants and annual herbs. Across plant life histories, as reproductive adult abundance increased, RTLs decreased. Highly variable RTLs were observed in species with multiple reintroduction events, suggesting local processes are just as important as life-history strategy in determining reintroduction outcomes. Time lags in restoration outcomes highlight the need to scale success benchmarks in reintroduction monitoring programs with plant life-history strategies and the unique demographic properties of restored populations. Drawing conclusions on the long-term success of plant reintroduction programs is premature given that demographic processes in species with slow life-histories take decades to unfold.     

Pyrrolizidine alkaloid content in <Emphasis Type="Italic">Senecio</Emphasis>: ontogeny and developmental constraints

Summary. The ontogeny of pyrrolizidine alkaloid (PA) synthesis and constraints on defence level during the seedling stage were examined in the annual Senecio vulgaris and the monocarpic perennial Senecio jacobaea. In both species, PAs were actively synthesized from the onset of seedling growth so that juvenile stages did not go through an undefended stage. Roots are known to be the exclusive sites where PAs are produced. Root biomass was the single most important biomass parameter explaining variation in total PAs per seedling. All correlation coefficients between—relative growth rate and PA concentration were negative, but none was significant. However, a significant negative—correlation was found between shoot to root ratio and PA concentration in S. jacobaeaseedlings, suggesting a dilution effect of the PAs. Earlier studies have shown that the shoot to root ratio is positively correlated with relative growth—rate of established S. jacobaea plants. It is therefore suggested that young S. jacobaea plants with a high shoot to root ratio and hence a high growth capacity necessarily have lower PA defence levels than plants with a low shoot to root ratio. Received 10 July 2002; accepted 16 November 2002.     

水分亏缺时氮磷营养对春小麦幼苗抗逆性的影响

在盆栽条件下研究了水分亏缺时，氮、磷营养对春小麦幼苗渗透物质及相关保护酶活性的影响．结果表明：水分胁迫使春小麦幼苗叶片游离脯氨酸、可溶性糖含量增加，RWC降低，POD、CAT活性增强．随着水分亏缺加剧，氮营养相应地提高了幼苗叶片脯氨酸、可溶性糖含量以及POD、CAT活性；磷营养仅能提高叶片脯氨酸含量以及POD活性，但使其可溶性糖含量以及CAT活性维持在较低水平上．施肥使叶片RWC降低．春小麦的抗逆性指标之间存在相关性，特别是小麦幼苗叶片POD活性与游离脯氨酸累积量之间有极显著正相关关系，其决定系数r^2为0．7472．图1表2参12