Light‐induced reduction of FE3+ as related to causes of chlorosis in cotton

In growth chambers, cotton (Gossypium hirsutum L. genetic selection ‘M8') was grown in a synthetic growth medium under four light regimes: low pressure sodium (LPS), LPS + Incandescent (Inc), cool white fluorescent (CWF) and CWF + Inc lamps at 22 C under LPS lamps. Less chlorosis developed at 26 C than at 22 C and less under LPS + Inc than under LPS lamps. All plants were green under CWF and CWF + Inc light. Green and chlorotic plant tissue contained about the same concentrations of Fe. The proposed hypothesis was that chlorotic tissue’ contained less Fe²⁺ than green tissue. Chlorotic leaves treated with FeSO₄ turned a green color. Enough CWF + Inc light passed through an intact leaf to reduce Fe³⁺ to Fe²⁺ in vitro. Also in vitro, Fe³⁺ was reduced by CWF, by Inc, but not by LPS light. The amount of Fe³⁺ reduced during an illumination period was directly proportional to the quantity of light used. In vitro, citrate and malate enhanced Fe³⁺ reduction, whereas phosphate, pyrophosphate, OH^‐, Cu²⁺, Ni²⁺, Mn²⁺, Zn²⁺, and F^‐ all inhibited Fe³⁺ reduction by light. Orthophosphate was about 8 times as effective as organic P in decreasing Fe³⁺ reduction. Citrate largely alleviated the inhibitory effects of Pi and pH (up to pH 6). The data also provide a possible explanation of a role for many of the elements known to induce or aggravate Fe chlorosis (inhibit Fe³⁺ reduction). Quantity and quality of light apparently play key roles in plant growth as related to reduction of Fe³⁺ to Fe²⁺ in plant tops.     

浙江省38种园林绿化植物对氟化氢气体的抗性及吸收能力

为充分发挥城市绿地吸收有害气体的生态功能,采用人工熏气法,对浙江省38种园林绿化植物对氟化氢气体的抗性及吸收能力进行了研究．通过系统聚类分析方法,将参试植物的抗性及吸收能力划分为弱、较弱、中等、较强和强等5个等级。结果显示,38种植物对氟化氢的抗性差异较大,抗性最强的熏气持续时间为9h（麦冬Ophiopogon japonicus）,抗性最弱的仅2h（枫香Liquidambar formosana等）;参试的落叶植物中弱和较弱抗性物种占87．50％,而常绿植物在弱至较强各等级的分布较均匀,表现出比落叶植物的抗性更强。植物对氟化氢气体的吸收能力差异非常显著,部分植物具有十分惊人的吸收能力。大叶榉Zelkova serrata的绝对吸收能力最强,达13．66g·kg^-1,是最小吸收能力植物湿地松（Pinus elliottii,117．06mg·kg^-1）的116．65倍;落叶植物中吸收能力中等的所占比例最大,为37．5％。常绿植物则由弱到强吸收能力等级呈现出逐渐递减趋势。试验各植物对氟化氢抗性与吸收能力线性相关不显著。     

氟化物熏气对橡胶叶碳代谢的某些影响

通过熏气模拟试验,研究了HF熏气后橡胶叶淀粉和一些可溶性糖含量的变化,以及活体条件下,HF熏气对一些相应酶活性的影响。结果表明:HF熏气后橡胶叶的总可溶性糖含量下降,淀粉和果糖含量上升,蔗糖含量下降,淀粉酶、琥珀酸脱氢酶、果糖二磷酸醛缩酶活性受到抑制。      

萘胺类化合物对氟中毒家蚕幼虫血液H2O2酶活性的影响

用 Na F、萘胺类化合物 CRL和增效剂处理 5龄用桑 ,氟中毒的蚕其血液过氧化氢酶活性大小依次为 :Na F处理区 >Na F CRL处理区 >Na F CRL 增效剂处理区 >对照 CK区 .说明 CRL和增效剂有明显的缓解家蚕氟中毒作用     

NaF和PFOS对斑马鱼肝脏抗氧化能力、非特异性免疫及组织结构的影响

为探讨有机氟化物和无机氟化物单一及联合暴露对斑马鱼(Danio rerio)肝脏的毒性效应,本研究将雄性斑马鱼随机分为对照组、氟化钠(NaF,无机氟)暴露组、全氟辛烷磺酸(PFOS,有机氟)暴露组、NaF+PFOS(无机氟及有机氟联合)暴露组,经15、30 d暴露试验后,检测了血液硝基蓝四氮唑(NBT)阳性细胞数及肝脏...     

氟对茶叶品质成分代谢的的影响

通过盆栽试验研究氟了对茶树新梢生长和品质成分含量的影响。适量增加土壤氟水平能提高新梢产量,但在高氟水平下新梢产量明显下降。茶多酚、咖啡碱及儿茶素(EGCG等)的含量随土壤氟水平的增加而逐渐降低,高氟水平下新梢的游离氨基酸含量也显著下降,苯丙氨酸解氨酶(PAL)、谷氨酸合成酶(GOGAT)的活性也随土壤和茶树氟浓度的增加而下降,说明氟可能抑制茶树儿茶素的合成代谢和氮素代谢。上述结果表明,氟对茶树生长和品质成分的影响与氟水平有关,虽然低浓度氟对茶树生长有一定的促进作用,但高浓度氟抑制茶树生长和茶多酚、氨基酸等品质成分的代谢。     

芝麻素对氟暴露斑马鱼生长性能及肠组织形态学的影响

为探讨芝麻素对氟暴露斑马鱼生长性能及肠组织形态学的影响，本试验将720尾斑马鱼随机分为6组，分别为对照组（CK）、芝麻素Ⅰ组（1 g，S1）、芝麻素Ⅱ组（2 g，S2）、80 mg/L氟暴露组（F）、80 mg/L氟暴露+芝麻素Ⅰ组（1 g，FS1）、80 mg/L氟暴露+芝麻素Ⅱ组（2 g，FS2），每组3个重复，每个重复40尾。并在试验第45、90天测量各组斑马鱼体长、体重、增长率（LGR）、增重率（WGR）、特定生长率（SGR），组织学法观察各组斑马鱼的肠组织结构，用Imageproplus图像软件系统测量肠道绒毛高度。结果发现，第45天时，与CK组相比，F组斑马鱼体重显著下降（P<0.05），添加芝麻素（FS1和FS2组）对其有一定改善作用但差异不明显（P>0.05）。试验第90天时，与CK组相比，F组斑马鱼体重和体长显著下降（P<0.05），添加芝麻素（FS1和FS2组）可一定程度上改善这种负作用，但效果并不显著（P>0.05）。在45和90 d时，F组LGR、WGR、SGR较对照组均下降，而FS1和FS2组较F组呈上升趋势。斑马鱼肠道组织切片观察发现，芝麻素还可在一定程度上改善氟暴露对斑马鱼肠道组织造成的负面效应。综上所述，芝麻素可对氟致斑马鱼生长及肠道组织的毒性效应产生一定缓解作用。     

硫酰氟熏蒸剂对基质栽培番茄、茄子经济性状及病害的影响

硫酰氟熏蒸剂用于基质消毒在国内尚未见报道。为明确硫酰氟熏蒸剂对基质栽培番茄、茄子经济性状、产量及番茄晚疫病、茄子青枯病等土传病害的影响,2013—2014年,进行了硫酰氟熏蒸剂基质消毒对番茄晚疫病、茄子青枯病的防效及对产量影响的试验研究。结果表明,硫酰氟熏蒸剂10、20、40 g/m33个供试剂量和3、5、7天3个熏蒸时间处理,其对番茄晚疫病、茄子青枯病的防治效果显著优于常规甲醛消毒处理,番茄、茄子作物的经济性状指标株高、茎粗明显增加,产量提高。处理效果随着硫酰氟用量的增加显著提高,硫酰氟不同熏蒸时间处理间差异不显著。生产上推荐硫酰氟熏蒸剂基质消毒40 g/m3熏蒸5天为宜。     

Diffusive Mobility of Fluoride in Soil: Some Mechanistic Aspects

Abstract

The diffusive mobility of fluoride (F) in soil (Entisol heplaquent) has been investigated as a function of soil water content and F‐concentration gradient. The data on F‐diffusion coefficients were recorded by determining the F‐concentration profile in horizontally incubated and homogenized soil columns, under varied experimental conditions (volumetric soil water content (θ)=0.12?0.25 cm³ cm^?3, initial concentration of F at source ([F]^t=0)=8?32 µM/g, pH=7.6±0.5, incubation time (t)=96 and 384 h, temperature=303±1.2 K). The effects of aluminum (Al) and calcium (Ca) ions, which are known to be strong binders for F in soil, on the F mobility have also been investigated by observing F diffusion in soils amended with externally added Al and Ca. The study suggests that F diffusion in soil increases with increase in θ and [F]^t=0. Further, when the soil was amended with Ca, F diffusion was observed to decrease regularly with the increase in Ca amount. In Al‐amended soil, when Al concentration is raised, F diffusion increases, at 96 h incubation time but decreases at 384 h incubation.