大气污染对珠江三角洲森林及土壤影响的初步研究

于1998年4月至1999年3月采用定点测定和面上调查相结合的方法,开展大气污染对珠江三角洲森林生长及其土壤酸碱性的肥力特性的影响研究。初步结果表明：大气污染引起珠江三角洲的地区发生大面积、高频率的酸雨,主要的污染物有SO、NOx、悬浮颗粒物等;随着污染程度的增大,森林土壤pH值降低,SO4^2-和AI^3 质量浓度增大;马尾松、湿地松叶片叶绿素含量降低,生长衰退甚至死亡;但不同树种对大气污染敏感程度不同,种植马占相思比马尾松更能增加林地对酸雨缓冲力和提高土壤肥力。     

不同演替阶段典型树种幼苗对酸胁迫响应的高光谱监测

通过在为期2a的可控酸雨试验下对处于不同演替阶段的典型树种幼苗的高光谱测定,得到不同梯度酸雨下各树种的叶片光谱反应曲线及相应叶片的生理生化参量.对测定的3种树种的叶片叶绿素含量及一阶导数光谱进行分析,发现随着酸雨浓度的增加,处于演替前期的先锋树种马尾松的幼苗叶绿素含量呈现增加趋势,而处于演替中、后期的木荷和青冈幼苗叶绿素含量则呈现减少趋势;随着试验时间的推移,马尾松的红边位置呈现"红移"趋势,其中pH2.5处理下的"红移"趋势较明显;而木荷和青冈的红边位置则呈现不同程度的"蓝移"趋势.较长时期高浓度酸胁迫对先锋树种马尾松的幼苗生长有一定促进作用,而对演替中期和后期树种木荷和青冈幼苗生长则主要表现为抑制作用.     

无土栽培下酸铝耦合对银杏生长的胁迫效应

本试验采用U₂₀₇均匀设计方案,通过无土栽培方法研究酸铝耦合处理对银杏幼株生长的效应。结果表明,在pH 4.5～5.5范围内,能耐铝（AlCl₃）浓度可达0.4 mmol/L,而高浓度（0.8～1.2 mmol/L）的铝对银杏有毒害作用;pH高于5.0时,提高培养液中铝浓度对银杏生长无明显影响。总之,酸铝耦合加剧对银杏植株的毒害作用,尤其对根系的伤害更为明显,甚至导致烂根死根,从而使地上部停止生长。     

Hydrogen Sulfide Alleviates Aluminum Toxicity in Germinating Wheat Seedlings

Protective role of hydrogen sulfide (H2S) on seed germination and seedling growth was studied in wheat (Triticum) seeds subjected to aluminum (Al3+) stress. We show that germination and seedling growth of wheat is inhibited by high concentrations of AICI3. At 30 mmol/L AICI3 germination is reduced by about 50% and seedling growth is more dramatically inhibited by this treatment. Pre-incubation of wheat seeds in the H2S donor NaHS alleviates AICI3-induced stress in a dose-dependant manner at an optimal concentration of 0.3 mmol/L. We verified that the role of NaHS in alleviating Al3+ stress could be attributed to H2S/HS- by showing that the level of endogenous H2S increased following NaHS treatment. Furthermore, other sodium salts containing sulfur were ineffective in alleviating Al3+ stress. NaHS pretreatment significantly increased the activities of amylases and esterases and sustained much lower levels of MDA and H2O2 in germinating seeds under Al3+ stress. Moreover, NaHS pretreatment increased the activities of guaiacol peroxidase, ascorbate peroxidase, superoxide dismutase and catalase and decreased that of lipoxygenase. NaHS pretreatment also decreased the uptake of Al3+ in AICI3-treated seed. Taken together these results suggest that H2S could increase antioxidant capability in wheat seeds leading to the alleviation of Al3+ stress.     

几个树种枝叶水浸液处理杉木6年后其生物量及分配

分别用杉木、木荷、丝栗栲,马尾松枝叶不同浓度水浸液处理杉木6年后测定其各器官的生物量及其分配,结果表明丝栗栲,马尾松,木荷水浸液处理杉木6年后,各器官的生物量有不同程度的提高,随着浓度加大其促进作用增强,在低浓度时有利于皮、枝和枯枝落叶生物量分配率,高浓度时有利于叶、根、干的生物量分配率,杉木水浸液处理杉木6年后,各器官生物量有不同程度的降低,随着浓度加大其抑制作用增加,在低浓度时有利于叶、皮、根,枝和干等各器官生物量分配率,高浓度时有利于枯枝落叶生物量分配率。     

Aluminum Inhibits the Fast Phase of Voltage-Dependent Calcium Influx into Synaptosomes

Aluminum has been shown to have neurotoxic effects, but the mechanisms by which it acts are not well understood. Because it has been reported that aluminum can interact with Ca2+-binding sites, the possibility that aluminum might interfere with Ca2+ influx into synaptosomes was examined. At concentrations of 50 microM and greater, aluminum significantly inhibited the fast phase (0-1 s) of the voltage-dependent uptake of 45Ca2+ into synaptosomes. Higher concentrations of aluminum also reduced 45Ca2+ uptake measured at 1 s in nondepolarizing media and inhibited the slow phase of 45Ca2+ uptake into synaptosomes whether they were suspended in either low K or high K media. The possibility that aluminum competitively inhibits the fast phase of Ca2+ influx was investigated. Aluminum (250 microM) increased the apparent KT (concentration of Ca2+ at which Ca2+ transport is half maximal) for 45Ca2+ of fast phase voltage-dependent channels and slightly decreased the maximal influx (Jmax). These effects are characteristic of a mixed type inhibitor, and the apparent Ki for Al3+ is estimated to be 0.64 mM. The interaction of aluminum with the fast phase of voltage-dependent calcium influx may disrupt intraneuronal calcium homeostasis and may also represent a means by which aluminum could accumulate intraneuronally.     

铝对秋茄幼苗生理特性的影响

为探讨铝对秋茄幼苗生理特性的影响,实验研究了不同浓度铝盐(0-100 mmol/L AlCl3)处理后秋茄的各种生理反应,对幼苗的生长、净光合效率、膜脂过氧化作用、游离脯氨酸含量等生理指标与胁迫程度及时间的关系作了对比研究,特别分析了高浓度(25-100 mmol/L Al3+)胁迫下,秋茄叶片和根部活性氧清除系统保护酶活性的变化趋势。研究发现,在10 mmol/L浓度以下,秋茄在生理特性上表现出对铝胁迫的最大适应性,能维持正常生命生长过程。当浓度增加至25-100 mmol/L,秋茄的生理反应较为敏感,膜脂过氧化加重,MDA含量及保护酶活性随铝浓度增加的变化趋势与其在海莲中的表现基本相似。高浓度铝胁迫的极端环境使植物体内产生过量的活性氧自由基,诱导了细胞膜系统的氧化损伤,最终导致秋茄植株衰老甚至死亡。抗氧化保护酶系统SOD、CAT、POD的协同作用,在一定时间内可以维持细胞内活性氧代谢平衡;特别是POD被激活的程度最大,且持续时间最长,可以考虑作为秋茄幼苗抗铝胁迫的生理标志。秋茄叶片和根部的游离脯氨酸含量在25和100 mmol/L Al3+胁迫下均显著增加。       

铝毒胁迫对乐昌含笑幼苗生长和生理的影响

为研究铝毒对乐昌含笑Michelia chapensis幼苗生长的影响,采用水培法对乐昌含笑幼苗进行铝胁迫实验,设置铝浓度梯度为0 (CK)、0.5 (T1)、1 (T2)、2 mmol·L^-1(T3)共4个处理,定期测定其根长、根尖铝含量、POD和CAT活性、MDA和脯氨酸(Pro)含量。结果表明,铝胁迫明显抑制乐昌含笑根的伸长生长,随着Al³⁺浓度的增加,抑制程度加剧,T1、T2、T3与CK对照比较,相对伸长率分别为84.53%、63.16%和54.46%;根尖铝含量随处理时间延长和铝浓度增加而增加,处理6 d时T1、T2、T3根尖铝含量分别是CK的 63.64、82.60、121.69倍;POD、CAT酶活性与处理时间和铝浓度呈正相关,各处理6 d时POD活性比处理1 d提高17.00%～115.21%,CAT活性提高25.11%～49.28%;MDA和Pro含量变化随着胁迫时间和铝溶液浓度的增加而增加,处理6 d 时T1、T2、T3的MDA含量比CK对照增加46.13%～59.78%,Pro含量增加60.12%～150.85%。在铝胁迫条件下,乐昌含笑根尖铝含量增加,根的伸长生长受抑制,细胞膜膜质过氧化程度增加;乐昌含笑可通过激活体内抗氧化酶系抵抗铝胁迫,同时产生脯氨酸调节细胞渗透势。     

The effect of aluminum exposure on root respiration in an aluminum-sensitive and an aluminum-tolerant cultivar of Triticum aestivum

The effects of aluminum (Al) exposure on intact root respiration of an Al-sensitive (Scout-66) and an Al-tolerant (Atlas-66) cultivar of Triticum aestivum were investigated. Exposure to a wide range of Al concentrations (0–900 μmol) for 4 days stimulated respiration along the energy-conserving cytochrome pathway in both cultivars and increased the ratio of maintenance respiration to growth respiration. The maximum rate of Scout-66 root respiration occurred after exposure to 100–200 μmol Al. Atlas-66 root respiration peaked after exposure to 300–400 μmol Al. Similarly, calculations of theoretical adenosine 5'-triphosphate (ATP) production indicated that maximum daily rate of ATP production also increased upon exposure to Al in both cultivars, with peak ATP production occurring during peak respiration. Maximum root respiration rates in both cultivars were related to the Al concentration that inhibited root growth. Temporal exposure to 200 μmol Al quickly stopped root growth and stimulated cytochrome pathway respiration in Scout-66 after 4 days. Atlas-66 root growth and respiration were unaffected by 200 μmol Al. These results suggest that Al exposure imposes a demand for additional metabolic energy. A model describing Al effects on root respiration is presented     

大气污染对珠江三角洲森林及土壤影响的初步研究

于1998年4月至1999年3月采用定点测定和面上调查相结合的方法,开展大气污对珠江三角洲森林生长及其土壤酸碱性和肥力特性的影响研究。初步结果表明大气污染引起珠江三角洲地区发生大面积、高频率的酸雨,主要的污染物有SO