模拟秋季酸雨对三角枫叶片光合生理特性的影响

以三角枫幼苗为材料,采用盆栽方法,研究了pH 5.6、pH 4.0、pH 3.0和pH 2.0酸度模拟酸雨胁迫对三角枫叶片光合生理特性的影响,以探讨酸雨胁迫下三角枫的光合生理响应机制。结果显示:(1)随着酸雨浓度的增加和胁迫时间的延长,三角枫叶片相对叶绿素含量下降幅度逐步增大;叶片丙二醛含量呈逐渐上升的趋势,且各处理均显著高于对照;叶片质膜透性和脯氨酸含量均呈先升高后降低的趋势,且pH 2.0处理的叶片质膜透性在试验20d时迅速增大,升高幅度最大(146.3%)。(2)叶片净光合速率、蒸腾速率、水分利用效率、表观光能利用效率以及表观CO2利用效率在胁迫下也均呈显著下降趋势,且以pH 3.0和pH 2.0处理降幅最大。研究表明,pH 4.0的模拟酸雨对三角枫叶片的光合生理指标无显著影响,而pH≤3.0的强酸雨胁迫使三角枫叶片叶绿素含量显著下降、膜保护系统受损、光合作用效率显著下降;三角枫能适应弱酸雨(pH≥4.0)环境,可作为酸雨地区的园林绿化树种。     

模拟酸雨对毛竹叶片抗氧化酶活性及释放绿叶挥发物的影响

为了探讨酸雨胁迫与毛竹(Phyllostachys pubescens)绿叶挥发物(green leaf volatiles, GLVs)释放规律以及抗氧化酶活性的关系, 通过盆栽试验, 采用不同pH值(5.6、4.0、2.5)的模拟酸雨对毛竹三年生实生苗进行处理, 研究酸雨对毛竹叶片可溶性蛋白质含量、丙二醛(MDA)含量和抗氧化酶活性的影响, 并采用热脱附/气相色谱/质谱联用技术对毛竹释放的GLVs成分和含量进行分析。结果表明: 酸雨胁迫下毛竹叶片MDA含量明显增加, pH 2.5模拟酸雨胁迫处理45天毛竹叶片MDA含量与对照相比增加了43.0% (p < 0.01); pH 4.0处理MDA含量增加缓慢, 处理75天时MDA含量比对照增加了0.36倍(p < 0.01)。pH 4.0和pH 2.5模拟酸雨胁迫处理45天时, 毛竹叶片可溶性蛋白质含量极显著增加, 与对照相比分别增加了32.0%和65.0% (p < 0.01)。在酸雨胁迫下, 毛竹叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的响应时间存在一定差异, 表现为互相协调, pH 2.5模拟酸雨胁迫处理SOD活性和POD活性分别在45天和60天时达到最大值, 分别为对照的1.67倍和1.31倍(p < 0.01), 随后降低。pH 4.0和pH 2.5模拟酸雨胁迫处理, 毛竹叶片GLVs含量比对照分别增加26.4%和132.9% (p < 0.01), 新增GLVs为 (E)-2-辛烯醛、2-乙基己醛、(E)-2-己烯醛和(E)-2-壬烯醛。研究表明: 酸雨胁迫条件下, 毛竹可以通过调节保护酶活性、可溶性蛋白质含量和释放GLVs来提高适应环境的能力。     

Effects of simulated acid rain on the activity of antioxidant enzyme and the emission of induced green leaf volatiles in Phyllostachys pubescens

为了探讨酸雨胁迫与毛竹(Phyllostachys pubescens)绿叶挥发物(green leaf volatiles, GLVs)释放规律以及抗氧化酶活性的关系, 通过盆栽试验, 采用不同pH值(5.6、4.0、2.5)的模拟酸雨对毛竹三年生实生苗进行处理, 研究酸雨对毛竹叶片可溶性蛋白质含量、丙二醛(MDA)含量和抗氧化酶活性的影响, 并采用热脱附/气相色谱/质谱联用技术对毛竹释放的GLVs成分和含量进行分析。结果表明: 酸雨胁迫下毛竹叶片MDA含量明显增加, pH 2.5模拟酸雨胁迫处理45天毛竹叶片MDA含量与对照相比增加了43.0% (p < 0.01); pH 4.0处理MDA含量增加缓慢, 处理75天时MDA含量比对照增加了0.36倍(p < 0.01)。pH 4.0和pH 2.5模拟酸雨胁迫处理45天时, 毛竹叶片可溶性蛋白质含量极显著增加, 与对照相比分别增加了32.0%和65.0% (p < 0.01)。在酸雨胁迫下, 毛竹叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的响应时间存在一定差异, 表现为互相协调, pH 2.5模拟酸雨胁迫处理SOD活性和POD活性分别在45天和60天时达到最大值, 分别为对照的1.67倍和1.31倍(p < 0.01), 随后降低。pH 4.0和pH 2.5模拟酸雨胁迫处理, 毛竹叶片GLVs含量比对照分别增加26.4%和132.9% (p < 0.01), 新增GLVs为 (E)-2-辛烯醛、2-乙基己醛、(E)-2-己烯醛和(E)-2-壬烯醛。研究表明: 酸雨胁迫条件下, 毛竹可以通过调节保护酶活性、可溶性蛋白质含量和释放GLVs来提高适应环境的能力。     

模拟酸雨对龙眼叶片气体交换和叶绿素a荧光参数的影响（英文）

 研究了模拟酸雨对龙眼(Dimorcarpus longana)叶片气体交换和叶绿素a荧光参数的影响,结果表明：酸雨胁迫抑制龙眼光合作用,受胁迫叶片光补偿点上升。pH 3.0的酸雨处理6 h后叶片气体交换和叶绿素a荧光参数下降,停止处理后72 h可以恢复。pH 2.5的酸雨处理6 h后净光合速率（Pn）、气孔导度(Cs)、蒸腾速率（Tr）,叶绿素a荧光参数Fv/Fo、Fv/Fm、PSII非环式电子传递的量子产量（ΦPSⅡ）、荧光下降比值（Rfd）、非光化学猝灭系数（qN）和光化学猝灭系数（qP）急剧下降,停     

模拟酸雨和铝调控对茶叶主要化学品质与铝积累的影响

为研究模拟酸雨和铝(Al)对茶叶主要化学品质与Al积累的影响及其交互作用,采用3个酸度水平(pH 3.0、4.0、5.0)和4种Al浓度水平(0、10、20、30 mg L-1),用溶液培养法研究茶叶的主要化学指标和Al含量的异同.结果表明,在模拟酸雨下,茶叶的茶多酚和咖啡碱含量随酸度增加先增加后下降,氨基酸、儿茶素和...     

Effect of long-term exposure to simulated acid rain on the development and reproduction of the predatory mite, <Emphasis Type="Italic">Euseius nicholsi</Emphasis> (Ehara <Emphasis Type="Italic">et</Emphasis> Lee) (Acari: Phytoseiidae)

The effects of simulated acid rain on the development and reproduction of E. nicholsi, an important natural enemy of many species of pest mites in China, were studied in the laboratory. The life history parameters of E. nicholsi were investigated after long-term (about 8 generations) exposure to various levels of simulated acid rain (pH 2.0, 3.0, 4.0, and 5.6). The results showed that the acid rain had negative effects on some basic parameters of the life history of the E. nicholsi population indirectly. The whole development durations with pH 3.0–5.6 treatments were longer and the duration with pH 2.0 treatment was shorter than with deionized water treatments (control). Adult longevity and oviposition duration were notably shortened, and female fecundity was decreased by an increase in acidity. The net reproductive rate (R ₀) of the populations treated with acid rain was less than that of the control populations and gradually decreased with an increase in acidity; however, the values of the intrinsic rate of increase (r) were not affected significantly by acid rain, and inhibitory effects of acid rain on the population growth of E. nicholsi were not recognized.     

Influence of acid rain and ozone on soil heavy metals under loblolly pine trees: A field study

A field growth chamber study was conducted to determine the effects of ozone and simulated acid rain (SAR) on soil heavy metals. Loblolly pine (Pinus taeda L.), grown in open-top chambers, was exposed to three concentrations of ozone (charcoal filtered air with 0.026 µL O₃ L^-1, and two non-filtered treatments in which ozone concentrations were 0.074 µL L^-1 and 0.147 µL L^-1, respectively) and two levels of SAR (pH 3.5 and 5.2). Ozone was applied for 12 h d^-1 for 9 months and acid rain deposition was 125 mm event^-1. After 9 months exposure, soil pH, organic matter and DTPA-extractable heavy metals (Cd, Pb, Zn, Mn, Fe, Cu) were determined on soil samples collected from exposed chambers at two depths (0–15 cm and 15–30 cm). Simulated acid rain decreased the original soil pH. The concentrations of Cd, Pb and Mn at SAR pH 3.5 were significantly higher than at SAR pH 5.2. Ozone did not affect Zn, Fe and Cu, but a significant interaction between pH and O₃ on Mn, Pb and Cd was observed. Due to the poor drainage capacity of this soil, leaching of heavy metals was not observed.     

模拟酸雨及其酸化土壤对小麦幼苗体内可溶性糖和含氮量的影响

以小麦为试材,采用盆栽方法研究了模拟酸雨及其酸化土壤对小麦幼苗体内可溶性糖和含N量的影响.结果表明,pH值为5.6、4.5、3.5、3.0和2.5的系列模拟酸雨引起了土壤酸化和盐基流失.当模拟酸雨的pH值由5.6下降到2.5时,被淋溶土壤的pH值由.0下降到3.41,土壤中交换性盐基总量从56.5下降到41.1mmol·kg^-1.将小麦幼苗栽培在该系列酸化土壤上,并分别用5种不同pH值的模拟酸雨喷淋地上器官,导致小麦幼苗体内的可溶性糖含量、含N量迅速下降,某些生理活动降低.其中,模拟酸雨喷淋对小麦幼苗茎叶可溶性糖含量、含N量、叶绿素含量以及光合速率的影响大于酸化土壤对其产生的影响.而酸化土壤对小麦幼苗根系中可溶性糖含量、含N量、硝酸还原酶(NR)和谷氨酸合成酶(GOGAT)活性的影响大于模拟酸雨喷淋的影响.pH≤3.0的高强度酸雨以及由其产生的酸化土壤(T₄、T₅土壤)对小麦幼苗的碳素代谢和氮素代谢具有明显的抑制作用.     

酸雨和采食模拟胁迫下克隆整合对空心莲子草生长的影响

研究表明克隆整合可以显著提升异质环境中克隆植物的生长,然而当克隆植物遭受均质环境压力时,整合对植物生长影响的研究相对较少。本文以典型入侵克隆植物空心莲子草（Alternanthera philoxeroides）为例,研究均质环境压力酸雨和采食模拟胁迫对空心莲子草生长的影响,以及克隆整合在空心莲子草适应不利环境过程中所起的作用。酸雨设3种浓度梯度：pH值3.5 、pH值4.5和 pH值6.5（对照）;采食设3种水平：不去叶、去叶50%和去叶90%;整合水平：匍匐茎切断和连接。结果表明：无论保持或切断匍匐茎的连接,酸雨处理都不影响空心莲子草生物量。当保持匍匐茎连接时,pH值4.5酸雨处理增加了空心莲子草匍匐茎长度和分株数目,因此,低度酸雨可能对空心莲子草生长有一定的促进作用。同样,无论匍匐茎是否被切断,采食处理都显著降低了空心莲子草克隆片段生物量,而显著增加了叶片数目。当切断匍匐茎连接时,采食处理使空心莲子草分株数目显著增加。本文得出的结论是：空心莲子草能较好地适应酸雨和采食的环境压力,当空心莲子草全部克隆分株遭受均质环境胁迫时,克隆整合并不能显著改善它的生长。     

Response of Soybean Seed Germination to Cadmium and Acid Rain

Cadmium (Cd) pollution and acid rain are the main environmental issues, and they often occur in the same agricultural region. Nevertheless, up to now, little information on the combined pollution of Cd(2+) and acid rain action on crops were presented. Here, we investigated the combined effect of Cd(2+) and acid rain on the seed germination of soybean. The results indicated that the single treatment with the low level of Cd(2+) (0.18, 1.0, 3.0?mg?L(-1)) or acid rain (pH ≥3.0) could not affect the seed germination of soybean, which was resulted in the increased activities of peroxidase and catalase. The single treatment with the high concentration of Cd(2+) (>6?mg?L(-1)) or acid rain at pH?2.5 decreased the activities of peroxidase and catalase, damaged the cell membrane and then decreased the seed germination of soybean. Meanwhile, the same toxic effect was observed in the combined treatment with Cd(2+) and acid rain, and the combined treatment had more toxic effect than the single treatment with Cd(2+) or acid rain. Thus, the combined pollution of Cd(2+) and acid rain had more potential threat to the seed germination of soybean than the single pollution of Cd(2+) or acid rain.     

Effects of simulated acid rain on the physiology of carmine spider mite, Tetranychus cinnabarinus (Boisduvals) (Acari: Tetranychidae)

Abstract:  The physiological effect of simulated acid rain sprayed on carmine spider mite Tetranychus cinnabarinus (Boisduvals) and host plant, were measured in a series of laboratory trials. We examined potential changes in three kinds of protective enzymes [peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT)] and three hydrolases [acid phosphatase (ACP), alkaline phosphatase (ALP) and carboxylesterase (CarE)] in response to changes in pH values of simulated acid rain at different time of exposure. POD, SOD and CAT activities increased significantly with the increase in the acidity of the acid rain, reaching the highest levels at pH 4.0 or 3.0, and then declined. Changes in ACP activity were similar to those observed in the protective enzymes. The increasing extent of the activities of these four enzymes after 30 and 45 days treatment became smaller than that after 15 days treatment . ALP activities decreased as pH value declined. There were no significant changes in CarE activities after 15 and 45 days, but that in pH 4.0 and 3.0 decreased after 30 days. The enhanced anti-oxidation enzyme levels (POD, SOD and CAT) and ACP activities in pH 4.0 and 3.0 reduced the effects of these toxic products on mites, resulting in the strengthening of the defensive power, and increase in survival and reproductive power of the mites, thus leading to an increase in the density of mites on host plant. From these results, we inferred that POD, SOD, CAT and ACP might be relevant to population changes of mites under acid rain pressure.     

The host plant-mediated impact of simulated acid rain on the development and reproduction of Tetranychus cinnabarinus (Acari, Tetranychidae)

Abstract:  The host plant-mediated impact of simulated acid rain (pH 3.0, 3.5, 4.0, 5.6, and 6.8) on the behaviour, development, and reproduction of carmine spider mite, Tetranychus cinnabarinus (Boisduvals), were evaluated at 25°C in a series of laboratory trials. The results indicated that the adults of carmine spider mite prefer to aggregate on pH 4.0 acid rain-treated eggplant leaves. The developmental times of nymph, larva and the pre-oviposition period of the mite on kidney bean leaves were significantly affected by acid rain treatments. The developmental times for the immature stages ranged from 11.4 days on pH 4.0 acid rain-treated leaves to 12.7 days on other acid rain-treated leaves. The survival of immatures varied from 85.14% on pH 4.0 acid rain-treated leaves to 78.83% on deionized water-treated leaves (pH 6.8). The mites feeding on acid rain-treated leaves (pH 3.0–5.6) had significantly greater reproductivity and longevity than those feeding on deionized water-treated leaves. The average greatest reproductivity (74.6 eggs per female) and longest female longevity (8.9 days) were recorded on pH 4.0 acid rain-treated leaves. Accordingly, the intrinsic rate of increase ( r _m ) for the mite on pH 4.0 acid rain-treated leaves was the highest. Jackknife estimates of r _m varied from 0.201 on pH 4.0 acid rain-treated leaves to 0.158 on pH 5.6 acid rain-treated leaves. The results implied that the population growth of the mite were enhanced by application of acid rain (pH 3.0–5.6) on host plants.     

Effects of simulated acid rain on germination,seedling growth and oxidative metabolism of recalcitrant‐seeded Trichilia dregeana grown in its natural seed bank

Increased air pollution in a number of developing African countries, together with the reports of vegetation damage typically associated with acid precipitation in commercial forests in South Africa, has raised concerns over the potential impacts of acid rain on natural vegetation in these countries. Recalcitrant (i.e. desiccation sensitive) seeds of many indigenous African species, e.g. must germinate shortly after shedding and hence, may not be able to avoid exposure to acid rain in polluted areas. This study investigated the effects of simulated acid rain (rainwater with pH adjusted to pH 3.0 and 4.5 with 70:30, H₂SO₄:HNO₃) on germination, seedling growth and oxidative metabolism in a recalcitrant‐seeded African tree species Trichilia dregeana Sond., growing in its natural seed bank. The results suggest that acid rain did not compromise T. dregeana seed germination and seedling establishment significantly, relative to the control (non‐acidified rainwater). However, pH 3.0 treated seedlings exhibited signs of stress typically associated with acid rain: leaf tip necrosis, abnormal bilobed leaf tips, leaf necrotic spots and chlorosis, reduced leaf chlorophyll concentration, increased stomatal density and indications of oxidative stress. This may explain why total and root biomass of pH 3.0 treated seedlings were significantly lower than the control. Acid rain also induced changes in the species composition and relative abundance of the different life forms emerging from T. dregeana's natural seed bank and in this way could indirectly impact on T. dregeana seedling establishment success.     

模拟酸雨对茄科3种蔬菜种子萌发的影响

采用pH 2.0、3.0、4.0、5.0的模拟酸雨和pH 6.5的中性溶液(ck)处理番茄、茄子、辣椒3种蔬菜种子,研究酸雨胁迫强度对3种蔬菜种子萌发的影响。结果表明：从发芽率、发芽势、发芽指数3个萌发指标来看,番茄种子在pH 2.0～3.0的强酸雨胁迫下,萌发受到轻微抑制;茄子种子在pH 2.0～5.0的酸雨胁迫下,萌发一直受到抑制,尤其是在pH 2.0的强酸雨胁迫时表现出萌发几乎完全受到抑制,而辣椒种子在酸雨胁迫下,萌发几乎没有受到抑制。3个萌发指标均随着酸雨pH值的减小而减少。pH 2.0～5.0酸雨胁迫下,辣椒吸水值的变幅（13.75）﹤番茄（19.91）﹤茄子（20.58）,同等酸雨胁迫强度下,根长抑制指数、蛋白质含量降幅、丙二醛增幅辣椒﹤番茄﹤茄子。这表明抗酸雨胁迫能力：辣椒>番茄>茄子。     

酸雨胁迫对苦槠幼苗气体交换与叶绿素荧光的影响

常绿阔叶树苦槠(Castanopsis sclerophylla)是亚热带地带性顶极群落的建群种之一, 在区域森林资源保护和可持续利用方面具有重要的地位。在该区域日益严重的酸雨胁迫下, 研究其对于胁迫的生理生态响应具有重要的理论价值和实践意义。该文以苦槠幼苗为研究材料, 研究了酸雨胁迫对苦槠幼苗光合生理的影响。结果表明: (1)短时间内, pH 2.5处理下的幼苗叶绿素相对含量最低, 且与pH 5.6处理下的存在显著性差异(p < 0.05); 经过一段时间处理后, pH 4.0处理下的叶绿素相对含量最高, 表明低浓度的酸雨会促进叶绿素相对含量的增加。(2) 2007年4月, 光合速率(P_n)、PSⅡ最大光化学效率(F_v/F_m)和PSⅡ的潜在活性(F_v/F₀)在不同酸雨浓度处理下基本无变化。随着酸雨处理时间的延长, pH 2.5处理下的P_n、光饱和点、光补偿点和暗呼吸速率有显著降低, 且与pH 5.6处理下的存在显著性差异(p < 0.05)。pH 2.5处理组与pH 5.6处理组之间的F_v/F_m和F_v/F₀差异性逐渐减小。表观量子效率和气孔导度变化规律不明显。综合来说, 酸雨处理前期, 高浓度的酸雨胁迫对苦槠幼苗叶绿素相对含量、光合生理参数有显著影响, 但随着酸雨处理时间的增加, 酸雨胁迫对苦槠幼苗的影响逐渐减小, 表明其对外界不良环境具有一定的抵御能力和适应能力。     

Responses of maternal siblings ofPinus densiflora to simulated add rain

Because most research on acid rain does not consider the genetic composition of seeds and the inherent variations in seed mass and germination date, the potentially diverse patterns of plant response are neglected within a population. Therefore, we examined the effects of both family identity and simulated acid rain onPinus densiflora seedlings over a 34-week period, beginning at germination. We were able to evaluate the importance of family and pH treatment independent of seed mass and germination date by considering the latter two variables as covariates. Seeds were collected from six randomly chosen trees that were assumed to represent different genotypes. After germination in a controlled environment, the seedlings were moved outdoors. Each was then subjected twice a week to 40 mL of simulated acid rain, at a pH of either 3.0 or 5.6. We examined variations in germination date, seedling height, needle numbers and lengths, and root and shoot masses. The maternal family effect was significant for all characters over the entire test period. Strong effects of pH treatment were detected only at the later growth stages. Artificial rain with a pH of 3.0 enhanced growth rates, particularly aboveground, compared with seedlings treated with pH 5.6 rain. However, regardless of pH, certain groups of maternal siblings consistently performed better in almost all parameters. The exception was for mean germination date, which differed among families only at a pH of 3.0. Therefore, although we demonstrated that acid rain affected both the date of germination as well as seedling growth rates inP. densiflora, the responses differed among maternal families, and were also associated with seed mass and germination date.     

Role of Simulated Acid Rain on Acer negundo and Plant Nitrition

The short-term effects of simulated acid rain on Acer negundo L. have been investigated using photoacoustic spectroscopy and modulated fluorescence measurements. Three seeding groups of Acer negundo L. were treated with simulated acid rain at pH 3.0, 4.5 and 5.6 levels for three months. The results indicated the photosynthetic activity, expressed in terms of normalized oxygen evolution signal, photochemical energy storage, normalized variable fluorescence (Fv/Fm), photochemical and non-photochemical chlorophyll fluorescence quenching, ranges in the order pH 4.5 > pH 3.0 > pH 5.6. This stimulation effect has been confirmed by increased growth rate observed in relation with increased acidity levels. The nutritional aspects of this favorable effect of the acid rain on plant growth were discussed.     

Response of Soil Respiration to Acid Rain in Forests of Different Maturity in Southern China

The response of soil respiration to acid rain in forests, especially in forests of different maturity, is poorly understood in southern China despite the fact that acid rain has become a serious environmental threat in this region in recent years. Here, we investigated this issue in three subtropical forests of different maturity [i.e. a young pine forest (PF), a transitional mixed conifer and broadleaf forest (MF) and an old-growth broadleaved forest (BF)] in southern China. Soil respiration was measured over two years under four simulated acid rain (SAR) treatments (CK, the local lake water, pH 4.5; T1, water pH 4.0; T2, water pH 3.5; and T3, water pH 3.0). Results indicated that SAR did not significantly affect soil respiration in the PF, whereas it significantly reduced soil respiration in the MF and the BF. The depressed effects on both forests occurred mostly in the warm-wet seasons and were correlated with a decrease in soil microbial activity and in fine root biomass caused by soil acidification under SAR. The sensitivity of the response of soil respiration to SAR showed an increasing trend with the progressive maturity of the three forests, which may result from their differences in acid buffering ability in soil and in litter layer. These results indicated that the depressed effect of acid rain on soil respiration in southern China may be more pronounced in the future in light of the projected change in forest maturity. However, due to the nature of this field study with chronosequence design and the related pseudoreplication for forest types, this inference should be read with caution. Further studies are needed to draw rigorous conclusions regarding the response differences among forests of different maturity using replicated forest types.     

模拟酸雨对西洋杜鹃生理生态特性的影响

采用盆栽方法,研究了不同pH值条件下的模拟酸雨对西洋杜鹃生长及其叶片主要生理生化特征的影响。结果表明:在酸雨胁迫下,随着酸雨胁迫的增强,西洋杜鹃叶片受害程度逐渐加重;叶片丙二醛含量逐渐升高;可溶性蛋白含量先升后降;过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性均呈先升后降的单峰曲线变化,其中pH值为4.3的处理下西洋杜鹃叶片CAT和SOD活性最高,pH值为3.0的处理下其POD活性最高;其叶绿素含量逐渐下降;叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)及水分利用率(WUE)均呈先升后降的趋势,而胞间CO2浓度(Ci)则持续下降,pH值为4.3的处理下其Pn、Tr、Gs和WUE均达到最高。研究表明,大致可以认为pH值≤3.0是酸雨对西洋杜鹃造成隐形伤害的阀值,而酸雨灾害严重地区的降水pH值为2.0—4.0左右,说明西洋杜鹃可以在酸雨灾害较重的地区生长,可作为酸雨灾害严重地区园林绿化及植被构建的物种之一。     

模拟酸雨对红壤区茶树器官氮磷含量及其化学计量比的影响

以红壤区25年生茶园为对象,开展pH 4.5、pH 3.5、pH 2.5及自来水(对照)4种强度模拟酸雨处理原位试验,于处理第3年收集茶树体不同功能根系和不同年龄枝、叶,测定氮(N)、磷(P)含量,并计算化学计量比和酸雨响应敏感度.结果表明: 土壤pH值、硝态N和有效P随酸雨强度增加而显著降低.吸收根N含量随酸雨强度增加而提高,pH 2.5处理下吸收根N含量与对照相比显著提高32.9%;储藏根P含量随酸雨强度增强而显著降低;同时酸雨处理显著提高吸收根N/P.新叶和老叶N、P含量对不同强度酸雨处理响应不敏感,但酸雨处理增加了老叶N/P,且在pH 3.5处理下达到显著水平.酸雨处理对枝条的影响与其年龄有关,新枝N含量和N/P在低强度酸雨(pH 4.5)处理下显著增加,而老枝N含量和N/P对酸雨处理响应不敏感.吸收根、新叶和新枝N含量对酸雨响应敏感度分别高于储藏根、老叶和老枝,而储藏根和叶片P含量对酸雨响应敏感度高于其他器官.茶树器官N含量对酸雨处理较为敏感,适度酸雨可增加幼嫩器官N含量和N/P,改变茶树体N、P的循环和平衡.