Effects of arsenic on seed germination and physiological activities in wheat seedlings

The effects of arsenic(As)were investigated on seed germination,root and shoot length and their biomass and some other factors to elucidate the toxicity of As.The results showed low concentrations of As(O-1 mg/kg)stimulated seed germination and the growth of root and shoot,however,these factors all decreased gradually at high concentrations of As(5-20 mg/kg).The contents Of O2-,MDA,soluble protein and peroxidase(POD)activity all increased with increasing As concentrations.Soluble sugar content,ascorbate peroxidase(APX),and superoxide dismutase(SOD)activities decreased at low concentrations of As,and increased at high concentrations of As.While acetylsalicylic acid(ASA)and chlorophyll contents,catalase(CAT)activity displayed increasing trend when the concentrations of As was lower than 1 mg/kg,and then decreasing trend.By polyacrylamide gel electrophoresis(PAGE).As induced the expression of POD isozymes of wheat seedlings.As induced the expression of CAT isozymes but inhibited the expression of SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg.However,As inhibited the expression of CAT isozymes but induced the expression of SOD isozymes at concentrations higher than 5 mg/kg.The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.     

绿僵菌防治第1代马尾松毛虫的研究

供试的绿僵菌和白僵菌菌种在室内对马尾松毛虫2～3龄幼虫的毒力相当.在25℃条件下,绿僵菌的n (LC50)=1.06×107 L-1, t (LT50) = 7.95～12.04 d (n(spore)=1.0×1011～1.0×107 L-1);白僵菌的n( LC50) =1.37×106 L-1 ,t (LT50) = 7.48～11.27 d ( n(spore) = 1.0×1011～1.0×107 L-1).试验显示与白僵菌相比,绿僵菌具有较强的耐高温和耐旱特性.在高温、低湿的条件下绿僵菌的杀虫效果优于白僵菌.林间防治试验也表明,绿僵菌防治第1代马尾松毛虫的效果显著优于白僵菌,显示出较好的应用前景.表8 参14     

The effect of olive mill wastewater on seed germination after various pretreatment techniques

Olive mill wastewater (OMW) management has been a major issue of environmental concern for olive oil producing countries. OMW can be a serious nuisance, when disposed of untreated, due to its significantly high organic load, its phytotoxic properties and its relatively low biodegradability. Field and plant irrigation with raw or pretreated OMW is an easy and relatively inexpensive method to treat and dispose of OMW. Typical pretreatment techniques could be comprised of phase separation through a settling basin, dilution with water, aeration to promote biological degradation and pH neutralization. A full factorial experimental design approach was used here to study the main effects and interactions of the above four pretreatment techniques on the germination of tomato and chicory seeds. Results of the study showed that the most statistically significant technique affecting OMW phytotoxicity is water dilution. The next most significant technique was aeration. In particular, phytotoxicity decreased with increased OMW dilution with water, when OMW was aerated and without pH adjustment. pH neutralization resulted in increased phytotoxicity. Settling did not significantly decrease the phytotoxicity of settled OMW and is therefore not considered necessary in an OMW management system in which plant irrigation is the goal. The interaction of aeration and pH was, marginally, the most significant two-way interaction for tomato seeds, while no interactions were significant when chicory seeds were used.     

重金属对西红柿种子发芽与根伸长的抑制效应

测定了水溶液和4种土壤中铜、锌、铅、镉单一污染对西红柿种子发芽与根伸长抑制率以及草甸棕壤条件下重金属复合污染的生态效应.结果表明,重金属对西红柿根伸长抑制率均明显大于对种子发芽抑制率.土壤重金属明显低于水体重金属对西红柿根伸长的抑制.抑制率大小排列为红壤>>草甸棕壤>栗钙土>暗棕壤.铜、锌、铅、镉对西红柿根伸长抑制率与土壤有机质、土壤凯氏氮、全钾含量显著线性负相关(P=0.05);与土壤pH值和土壤全磷含量线性不相关(P=0.05).重金属复合污染对西红柿根伸长表现为协同作用和拮抗作用.     

铜对夏腊梅种子萌发及抗氧化酶活性的影响

采用室内水培试验,研究不同浓度的外源铜处理对夏腊梅(Sinocalycanthus chinensis)种子萌发、根伸长抑制率、呼吸强度、丙二醛及抗氧化酶系统的影响.结果表明,(1)铜浓度与夏腊梅根伸长抑制率呈显著正相关(P＜0.01),但与萌发率相关性不显著.(2)铜处理对夏腊梅种子的过氧化物酶(POD EC1.11.1.7)具有激活效应,且随着铜浓度的增加激活效应逐渐增强.丙二醛(MDA)含量随铜浓度的增大先略降而后逐渐升高.对超氧化物歧化酶(SOD EC 1.15.1.1)和过氧化氢酶(CAT EC 1.11.1.6)存在胁迫初期低浓度下的激活效应,随着铜浓度的增加及胁迫时间的延长,表现为抑制效应,且随着铜浓度的增加抑制效应逐渐增强.     

Joint effects of heavy metal binary mixtures on seed germination, root and shoot growth, bacterial bioluminescence, and gene mutation

This investigation was to assess the joint effects of metal binary mixtures on seed germination,root and shoot growth,bacterial bioluminescence,and gene mutation based on the one toxic unit(1 TU)approach.Different sensitivities and orders of toxicity of metal mixtures were observed among the bioassays.In general,mostly additive or antagonistic effects were observed,while almost no synergistic effects by the binary metal mixtures in all bioassays.Therefore,the combined effects of heavy metals in the different bioassays were difficult to generalize since they were dependent on both chemical type and the organism used in each bioassay.However, these results indicate that a battery of bioassays with mixture chemicals as opposed to just a single assay with single metal is a better strategy for the bioassessment of environmental pollutants.     

毛竹入侵对常绿阔叶林主要树种的化感作用研究

为探讨毛竹入侵对周边森林环境的影响,以毛竹浸提液处理苦槠、青冈种子,测定种子萌发效应.结果表明,两树种种子萌发与浸提液浓度和来源有关.浓度效应表现为高抑低促的作用规律,高浓度处理下苦槠的发芽率为对照的82.3%~102.2%,青冈为对照的80%~90.9%,而低浓度处理下分别为对照的101.7%~107.6%和94.9%~109.1%.除低浓度处理对苦槠发芽速度无影响外,其他处理均对两树种发芽速度有显著的延缓作用(P<0.05).高浓度浸提液对苦槠根系活力有显著的抑制作用(P<0.05),抑制率为41.1%~62.4%.不同来源浸提液处理间差异明显,根系浸提液处理的种子发芽率最低.苦槠芽苗的芽长与不同来源浸提液间差异不显著(P>0.05),而青冈芽苗芽长与不同来源浸提液间差异显著(P<0.05),茎叶、根系与枯落物浸提液高于土壤浸提液.这些结果说明毛竹具有潜在的化感作用,可能有利于其入侵周边森林,从而危害周边森林环境.     

铜、镉胁迫下荻种子的萌发和幼苗生长

研究了不同质量浓度Cu、Cd胁迫对荻(Triarrhena sacchariflora(Maxim.)Nakai)种子萌发及其幼苗生长的影响。结果表明:随着胁迫质量浓度的增大,Cu、Cd对荻种子萌发和幼苗生长的抑制作用增强。就发芽率来看,影响荻种子萌发的Cu的临界质量浓度和极限质量浓度分别为20.81、67.37 mg·L-1,Cd的临界质量浓度和极限质量浓度分别为16.30、42.79 mg·L-1。Cu、Cd对荻幼苗根的抑制作用大于对芽的抑制作用;芽的生长表现为低促高抑。影响荻幼苗芽生长的Cu的临界质量浓度和极限质量浓度分别为52.32、96.11 mg·L-1,Cd的临界质量浓度和极限质量浓度分别为33.55、55.88 mg·L-1;影响荻幼苗根生长的Cu的临界质量浓度和极限质量浓度分别为42.33、85.03 mg·L-1,Cd的临界质量浓度和极限质量浓度分别为26.18、50.45 mg·L-1。     

Challenges to Introducing and Managing Disturbance Regimes for Holocarpha macradenia, an Endangered Annual Grassland Forb

Abstract:  Introducing rare plants to new sites for conservation to offset effects of habitat destruction requires detailed knowledge of habitat requirements, plant demography, and management needs. We conducted a factorial experiment replicated at three coastal prairie sites to test the effects of clipping frequency and litter accumulation on seed germination, seedling survival, reproduction, and seedling recruitment of introduced populations of the endangered, tall-stature, annual forb, Holocarpha macradenia (DC.) E. Greene. Clipping favored H. macradenia , primarily by enhancing seed germination and flower production. Litter accumulation had no effect on seed germination, even after 5 years of treatments. Seedling recruitment was highly site specific with large numbers of recruits recorded at only one of three sites. Although recruitment of seedlings was higher in clipped plots for 2–3 years, by 4–5 years after introduction very few seedlings survived to reproduction in any treatment. We attribute this result to a combination of poor habitat quality, small population size, and lack of a seed bank. We were unsuccessful in introducing this relatively well-studied species of concern to apparently suitable habitat at multiple sites in multiple years, which suggests that translocating rare plant populations to mitigate for habitat destruction is an expensive and highly uncertain endeavor.