Kinetics of Zinc Uptake and Anatomy of Roots and Leaves of Coffee Trees as Affected by Zinc Nutrition

Abstract

The influence of silicon (Si) (2.5 mM), sodium chloride (NaCl) (100 mM), and Si (2.5 mM) + NaCl (97.5 mM) supply on chlorophyll content, chlorophyll fluorescence, the concentration of malondialdehyde (MDA), H₂O₂ level, and activities of superoxide dismutase (SOD; E.C.1.15.1.1.), ascorbate peroxidase (APx; E.C.1.11.1.11.), catalase (CAT; E.C.1.11.1.6.), guaiacol peroxidase (G-POD; E.C.1.11.1.7.) enzymes, and protein content were studied in tomato (Lycopersicon esculentum Mill c.v.) leaves over 10-day and 27-day periods. The results indicated that silicon partially offset the negative impacts of NaCl stress with increased the tolerance of tomato plants to NaCl salinity by raising SOD and CAT activities, chlorophyll content, and photochemical efficiency of PSII. Salt stress decreased SOD and CAT activities and soluble protein content in the leaves. However, addition of silicon to the nutrient solution enhanced SOD and CAT activities and protein content in tomato leaves under salt stress. In contrast, salt stress slightly promoted APx activity and considerably increased H₂O₂ level and MDA concentration and Si addition slightly decreased APx activity and significantly reduced H₂O₂ level and MDA concentration in the leaves of salt-treated plants. G-POD activity was slightly decreased by addition of salt and Si. Enhanced activities of SOD and CAT by Si addition may protect the plant tissues from oxidative damage induced by salt, thus mitigating salt toxicity and improving the growth of tomato plants. These results confirm that the scavenging system forms the primary defense line in protecting oxidative damage under stress in crop plants.     

Effects of simulated acid rain on the growth,nutrition, foliar pigments and photosynthetic rates of sugar maple and white spruce seedlings

Sugar maple (Acer saccharum Marsh.) and white spruce (Picea glauca (Moench) Voss) seedlings were exposed to simulated acid rain (SAR) of pH 3.2, 4.3 and 5.6 for two and one-half growing seasons. Ambient rain was excluded from the treatment plots by mobile rain exclusion canopies. Sugar maple seedlings treated with pH 3.2 SAR had significantly higher foliar concentrations of nitrogen, sulphur and manganese, compared to either the pH 4.3 or 5.6 treated seedlings. The pH 3.2 treated seedlings also tended to have greater growth and photosynthetic rates compared to the pH 4.3 and 5.6 treated seedlings. In contrast, the pH 3.2 treated white spruce seedlings tended to have decreased growth and lower foliar potassium concentrations relative to the pH 4.3 and 5.6 treated seedlings. Statistically there were no significant treatment differences in seedling height, seedling diameter, foliar pigments, or photosynthetic rates in either the sugar maple or white spruce seedlings.     

镧对西葫芦幼苗模拟酸雨胁迫的缓解效应

以西葫芦为材料, 研究了模拟酸雨胁迫下适量镧（La）对幼苗生长及叶绿素、可溶性蛋白和脯氨酸含量的影响。结果显示, 镧处理对酸雨胁迫有一定的缓解作用. 在pH 3.5和3.0 时,幼苗鲜重均显著高于模拟酸雨组,并恢复到对照的94.7%和78.6%;但在其他胁迫强度下, 镧处理的缓解效应不显著。叶绿素和可溶性蛋白的含量变化与幼苗鲜重类似,在pH 3.0时镧处理的缓解效应最显著;pH 3.5时镧处理的可溶性蛋白含量超过对照。脯氨酸含量呈现持续上升趋势,且镧处理可增加脯氨酸的积累,但只有pH 3.5和3.0 时显著高于模拟酸雨组。表明镧处理只对中强模拟酸雨胁迫有显著的缓解效应。     

The effect of “acid rain” and mineral fertilizers on the biometrical features of larix decidua mill. Seedlings

The purpose of the present experiment was to describe the influence of various mineral fertilizers on the development of Larix decidua Mill. seedlings subject to the influence of simulated acid rain of pH 2.5, 3.0, 3.5, 4.0, 4.5. The seedlings were fertilized every month (from April up to October), in order to counteract acid rain. The composition of the fertilizers was diversified in order to select an optimum variant. Fertilizer with NK applied to the needles (Florovit) and NPK applied to the soil (Fruktus 2) as well as dolomite lime applied to the soil. One row per set was left without fertilization as a control for each pH step of acid rain treatment. The analysis of biometric characteristics showed that a two-year period of investigations was too short to estimate effects on Larix decidua Mill. seedlings. It, however, indicated important trends. High correlations were found between particular growth parameters i.e. diameter of root neck, root mass, total mass of: seedlings, needles, main shoots, lateral shoots, ligneous parts, total overground parts. No strong correlations were observed between the above mentioned parameters and the total height of the seedlings. Among the different treatments the best development was achieved at pH 4.0, whereas the weakest development was observed at pH 2.5. The analysis showed a decrease in biometrical features along with an increase in acidity of acid rain solution. The first year of the experiment had the greatest influence upon the growth of Larix decidua Mill. seedlings. Significant improvement in growth, in relation to control plots, was achieved by using NK-fertilizers onto needles — the best results, and NPK onto soil. The best increment of the height of seedling was noticed at pH 3.5. In the second year of the experiment the effects of pH of acid rain and fertilization decreased — no significant effect on biometrical features was observed. Applaying NPK fertilizer onto soil showed a positive effect in relation to dolomite treatment. The best increment was noticed at pH 4.0.     

A two-year experience on 15N-urea fertilization of a corn field amended with fly ash

Soybean seedlings (Glycine max) were exposed to simulated acid rain containing sulfate ion only or a mixture of sulfate, nitrate and chloride anions, using a continuous rain generating system in a side opened glasshouse. Plants were subjected to acid rain treatment twice a week, for a 1 or 3 hr period at a rate of 2.2 or 5.0 mm hr^?1, respectively. Dry seed yield in plants treated with simulated acid rain at pH 2.0, in the three of 4 experiments conducted over a 3 yr period, was significantly less than that at pH 3.0 or higher. Simulated acid rain treatment at pH 3.0 or higher did not significantly affect yield compared to pH 5.6; however, plants exposed to simulated acid rain at pH 4.0 tended to yield more than those treated with pH 5.6 rain. Based on the current 3 years of research in which results from 4 experiments were combined, rain acidity at current levels in Japan would not directly affect seed production of selected cultivars of soybean.     

Cd胁迫下绿豆和箭舌豌豆叶片抗氧化系统的变化

研究了Cd胁迫下绿豆（Phaseolus aureus）和箭舌豌豆（Vicia sativa）幼苗的生长,叶片内过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）、超氧化岐化酶（SOD）、愈创木酚过氧化物酶（GPOD）和谷胱甘肽还原酶（GR）的同工酶活性,还原性谷胱甘肽（GSH）和抗坏血酸（ASC）以及Cd含量的变化。结果显示,100μmol.L-1Cd胁迫9d期间,随着Cd胁迫时间的延长,绿豆和箭舌豌豆幼苗主根的伸长量和其根系干重显著降低（P〈0.05）,根表面出现越来越明显的褐色,绿豆叶表面出现可见的褐色斑点;两种植物叶片的CAT、APX和SOD同工酶活性以及绿豆叶片的GR活性呈先升后降的趋势,而两种植物叶的GPOD活性明显增加;在箭舌豌豆叶片中,GR活性随Cd暴露时间的延长而增加,而GSH先降后升;在绿豆叶片中,GSH和ASC随Cd暴露时间的延长而降低;与此同时,两种植物叶片中Cd的含量也随Cd胁迫时间的延长而增加,和箭舌豌豆相比,绿豆叶片中Cd含量增加更多。结果表明,箭舌豌豆有较强的抗氧化能力。     

Phenological Disorder Induced by Atmospheric Nitrogen Deposition: Original Causes of Pine Forest Decline over Japan. Part I. Phenological Disorder,Cold Death of Apical Shoots of Red Pine Subjected to Combined Exposures of Simulated Acid Rain and Soil Acidification,and Implications for Forest Decline

Seeds of red pine (Pinus densiflora Sieb. and Zucc.) were sown in red-yellow soil artificially adjusted to pH (H₂O) 4.10, 4.60 or 5.90 by adding H₂SO₄ solution to the soil (pH 5.90), and the three-month seedlings were exposed to simulated acid rain at pH 2.0, 3.0 or 5.6 for 10 minutes once, 3 times a week, for 12 months from 4 August 1994 to 3 August 1995 alone or in combination. Significant interactive effects between acid rain and soil acidification on growth and whole-plant net photosynthetic rate, and cold death ratio of new apical shoots following a cold snap were observed in a quadratic response pattern. The simulated acid rain increased budburst, new needle spread and elongation, and new apical shoot death percentage following a cold snap, but did not induce visible injury. In the highest soil acidity treatment at a soil pH 4.1, whole-plant net photosynthetic rate and seedling height exhibited a quadratic responses with increasing rain acidities. On the other hand, soil acidification caused leaf yellowing. The death percentage of new apical shoot of seedlings exposed to rain pH 2.0 following a cold snap was linearly enlarged with increasing soil acidities. With increasing soil acidity, height and whole-plant net photosynthesis of the seedlings exposed to rain pH 3.0 exhibited a linear increase response, while height of seedlings exposed to control rain exhibited a quadratic response. It is suggested that the results provide experimental evidency for phenological disturbances and an enhancement of frost risk by direct acid rain and indirect longterm soil acidification which may be significant in forest decline.     

Exogenously Applied Citric Acid Enhances Antioxidant Defense and Phytoextraction of Cadmium by Willows (<Emphasis Type="Italic">Salix</Emphasis> Spp.)

The effect of exogenously applied citric acid (CA) on phytoextraction and antioxidant defense was analyzed using willow species (Salix viminalis, S. alba, and S. matsudana) grown in soil contaminated with cadmium (Cd). Citric acid has been used as a chelating agent for the purpose of accelerating the solubility of Cd in soil and enhancing the phytoextraction of selected plants. Willows were exposed to 6 mg/kg of Cd, following the same with citric acid (20 mM/kg soil). Results revealed a positive effect of citric acid in mobilization of accumulated Cd from roots to shoots and leaves. The addition of citric acid alleviated Cd toxicity by helping plants to overcome oxidative stress, through CA’s chelating properties and the increased activity of antioxidant enzymes. Different protection strategies were evident through modification of activities of antioxidant enzymes such as catalase (CAT), ascorbate-peroxidase (APx), and guaiacol peroxidase (GPx) in young versus mature leaves in plants exposed to Cd. Furthermore, results revealed that addition of citric acid may be beneficial in the reduction of the negative effect of Cd stress on photosynthesis. The efficiency of coupling phytoextraction with the chelating agents represents a good strategy for decreasing damages caused by cadmium and has good potential in decontamination of a polluted environment.     

Antioxidative enzymes in the response of buckwheat (Fagopyrum esculentum moench) to ultraviolet B radiation

The behavior of the enzymatic antioxidant defense system was studied in buckwheat leaves and seedlings subjected to short-term enhanced UV-B radiation. The effects of UV-B action were monitored immediately after irradiation as well as after recovery. The applied dose induced an increase in lipid peroxidation and total flavonoid content, a decrease in chlorophyll content, and a change in enzymatic digestibility of extracted DNA. The activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase, and soluble peroxidase, as well as the isoelectric focusing (IEF) pattern of peroxidase isoforms, was analyzed. In treated as well as recovered seedlings, soluble and ascorbate peroxidase activities were increased. The activity of SOD was not altered, whereas CAT activity was decreased. In contrast to seedlings, only CAT activity was increased in treated and recovered leaves.     

Interaction of Ph and Mn on Physiological Parameters of Brassica Oleracea L.

In the present study, interaction of 4 levels of manganese (Mn²⁺) (0, 100, 200, and 400 mM) and 4 levels of pH (4.5, 5.5, 6.5, and 7.5) were investigated on some physiological parameters of Brassica oleracea L. after 30 days of growth (15 days treatment) in hydroponic culture. Results showed that with an increase in manganese concentration, soluble carbohydrates, protein, and ascorbate contents also increased in shoots and roots of Brassica oleracea L. However, higher concentration of manganese reduced soluble carbohydrates, protein and ascorbate contents in the same plant. As manganese concentration increased, catalase activity in roots and shoots was also remarkably increased. Moreover, root peroxidase activity at pH 4.5 increased with an increase in manganese concentration and this increase was highest at pH 4.5 and 400 mM manganese concentration.     

Antioxidant enzymes and DPPH-radical scavenging activity in chilled and heat-shocked rice (Oryza sativa L.) seedlings radicles.

Chilling whole rice seedlings at 5 degrees C significantly increased the time needed to recover linear growth and reduced the subsequent linear rate of radicle growth. Subjecting nonchilled seedlings to a 45 degrees C heat shock for up to 20 min did not alter subsequent growth, whereas a 3 min heat shock was optimal in reducing growth inhibition caused by 2 days of chilling. The activity of five antioxidant enzymes [superoxide dismutase (EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), ascorbate peroxidase (APX; EC 1.11.1.11), glutathione reductase (GR; EC 1.6.4.2), and guaiacol peroxidase (GPX; EC 1.11.1.7)] and DPPH (1,1-diphenyl-2-picrylhydrazyl)-radical scavenging activity were measured in heat-shocked and/or chilled radicles. Heat shock slightly increased the activity of CAT, APX, and GR and suppressed the increase of GR and GPX activity during recovery from chilling. Increased CAT, APX, GR, and DPPH-radical scavenging activity and protection of CAT activity during chilling appear to be correlated with heat shock-induced chilling tolerance.     

Effects of acid precipitation on embryonic mortality of Ambystoma salamanders in the Connecticut Valley of Massachusetts

The phenomenon of increased embryonic mortality of the spotted salamander Ambystoma maculatum concomitant with breeding pond acidification from acid rainfall was investigated in the Connecticut Valley of Massachusetts. The pH and chemistry of rain and pond water were analysed, and embryonic mortality of spotted and Jefferson salamanders A. jeffersonianum was monitored in 1976 and 1977.Rainfall pH, 4·16 and 4·07 in 1976 and 1977, respectively, indicates that acid rain continues to occur in the area. Ambystoma breeding ponds are acidic, due to background and rainfall acidity. The average pH of six ponds dropped from 5·62 in 1976 to 5·10 in 1977. Pond pH decreased up to 0·75 pH units following heavy rainfall. These trends indicate that pond acidification from acid rain is occurring.Despite pond acidity, embryonic mortality of spotted and Jefferson salamanders was low. For spotted salamanders, mortality ranged from 2·1 to 30·2%, with 15 of 17 ponds below 16%. Embryonic mortality of Jefferson salamanders ranged from 12·4 to 40·3%. No significant correlation between pond pH and percent embryonic mortality was found.Estimates based on numbers of breeding females showed Connecticut Valley spotted salamander populations to be larger than in areas where their decline has been correlated with acid rain. The size of present populations, and the embryonic acid tolerance exhibited by spotted and Jefferson salamanders, indicate that acid rain has not affected their populations in the Connecticut Valley of Massachusetts.     

Drought tolerance in four-day-old seedlings of a drought-sensitive cultivar of wheat

Four-day-old seedlings of spring wheat (Triticum aestivum L. cv. Marvdasht) can tolerate severe dehydration and recover after re-watering. In order to clarify tolerance mechanism, in a completely randomized design, the seedlings were exposed to drought by complete water cessation for 10 and 20 days, followed by re-watering for 3 and 7 days. Upon dehydration, the activity of α-amylase increased whereas growth parameters; photosynthetic pigments; and the activities of lipoxygenase, indole acetic acid (IAA) oxidase, and ascorbate peroxidase (APX) decreased. The activity of APX and the expression of its gene, however, increased after re-watering. Prolonged dehydration was also accompanied by increase in sucrose, soluble proteins, fructans, and certain amino acids, e.g. proline, glutamine, and valine. The results indicated that during dehydration, 4-day-old wheat seedlings shifted their energy expenditure from basal metabolism to withstand water deficiency via lowering the activity of membrane-damaging enzymes and enhancing the production of osmoprotectants.     

Effect of simulated acid rain on the growth of soybean

Soybean seedlings (Glycine max) grown in a glasshouse were exposed to simulated acid rain using a solution of deionized water containing sulfate, nitrate and chloride in concentrations and proportions equivalent to those in ambient rain water. Plants were subjected to acid rain treatment twice a week during the growing season, for a 1 hr period at a rate of 5 mm hr^?1. When the acid rain was below pH 3.0, visible symptoms developed in the young trifoliate leaves. However, at a pH above 3.0 there was no evidence of visible leaf injury; also tissue dry weights and leaf areas were not affected even after 7 weeks of exposure. The number of root nodules in plants exposed to acid rain at pH 4.0 tended to be higher than those of control plants maintained at pH 5.6, but decreased subsequently with decreasing pH. Based on our results current ambient levels of rain acidity in Japan should not have an adverse impact on seedling growth in soybean.     

钐-甘氨酸-维生素B6对酸雨胁迫下大豆幼苗的影响

试验研究钐-甘氨酸-维生素B_6(Sm-Gly-VB_6)对模拟酸雨伤害大豆幼苗的防护作用结果表明,在pH2.5酸雨胁迫下大豆幼苗叶绿素含量减少,叶绿素a/b值下降,细胞质膜透性增加,过氧化氢酶(CAT)活性下降。而同一强度酸雨胁迫下经50mg/kg Sm-Gly-VB_6预处理的大豆幼苗叶片叶绿素含量、细胞质膜透性与过氧化氢酶活性损伤较轻,对酸雨伤害大豆幼苗有一定缓解效应。     

Impacts of Acid Rain on Base Cations,Aluminum, and Acidity Development in Highly Weathered Soils of Thailand

The impacts of simulated acid rain on leachability of major plant nutrients, toxic element [aluminum (Al)], and acidity development in highly weathered tropical soils of Thailand were studied. Leaching experiments were conducted on soil columns with acidic solutions of pH 5.0, 4.0, 3.0, 2.0, and with water of pH 7.0 as a control treatment. Leaching losses of base cations from all soils increased with the decrease in pH associated with simulated acid rain (SAR) additions, and were found to be quite high under SAR with pH 2.0. The leaching removal of these cations was lesser at pH 3.0, 4.0, and 5.0 but greater than that in pH 7.0. The leaching of base cation from the soils depended not only on acid rain pH but also on soil properties, especially cation exchange capacity, soil texture, and initial base content. The significant losses of major plant nutrients [such as potassium (K⁺), calcium (Ca²⁺), and magnesium (Mg²⁺)] from the plant root zone over extended periods could cause nutrient imbalance and lower soil productivity.     

Counteracting the negative effects of simulated acid rain on the development of Larix decidua Mill. seedlings by means of mineral fertilization (NPK)

The experiment was aimed at estimating the effect of mineral fertilization with ternary mineral fertilizers (NPK) on the development of Larix decidua Mill. seedlings remaining under the influence of simulated acid rain. The soils with a mechanical composition of poor loamy sands were treated with water solutions of H₂SO₄ of pH: 2.5, 3.0, 3.5, 4.0, 4.5, 7.8. and selected biometric features were measured. The experiment was carried over a period of 2 yr. The analysis of changes in the biometric features demonstrated that the poor alkaline reaction of water solutions (7.8), and strong acid (2.5) has a negative effect on the development of the Larix decidua Mill. seedlings, resulting in the limitation of the length increment, decrease in the mass of seedlings, mass of needles etc. Optimal development of the seedlings was at pH 4.0. A decrease in the biometric features analyzed together with an increase in the acidity of water solution was observed.     

Calcium Influence on Chilling Resistance of Grafting Eggplant Seedlings

Abstract

Calcium (Ca) influence on chilling resistance of grafting eggplant seedlings were studied in a hydroponic system. Under the calcium sufficient treatment, the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) in grafting seedlings at 5°C were all obviously higher than those of calcium deficiency, peaking at 36 h, 24 h, and 24 h chilling stress, respectively. Several parameters of cellular membrane fluidity, such as content of unsaturated fatty acid (UFA), the ratio of UFA to SFA (U/S), index of UFA (IUFA) also distinctively increased. The contents of malondialdehyde (MDA) and saturated fatty acid (SFA) were lower than those of calcium deficiency. This study suggests that the variation of parameters mentioned above might be caused by cellular calcium levels. Calcium content was potentially the main reason that grafting seedlings had higher chilling resistance than own-root seedlings. Calcium appears to play an important role in increasing chilling resistance of grafting eggplant seedlings.     

酸雨对木芙蓉幼苗光合作用及抗氧化酶活性的影响

以pH 5.6为对照,采用pH 4.0、pH 3.0、pH 2.0强度的酸雨对2年生木芙蓉进行人工模拟胁迫,研究酸雨胁迫对木芙蓉叶片可见伤害、质膜透性(Membrane Permeability,MP)、叶绿素(Chlorophyll,Chl)含量、抗氧化酶系统及气体交换参数的影响.研究结果表明,pH 2.0和pH 3...     

INFLUENCE OF DIFFERENT SEED PRIMING METHODS FOR IMPROVING SALT STRESS TOLERANCE IN LETTUCE PLANTS

Seeds of lettuce, variety Romaine were subjected to different priming treatments such as water, potassium nitrate (KNO₃) and gibberellic acid (GA₃). Seedlings obtained from primed (Pr) and nonprimed (NP) seeds were grown in a hydroponic culture system supplemented with 0, 100 or 200 mM sodium chloride (NaCl). The different physiological and biochemical responses were studied 15 days after treatment. Under NaCl, the dry weight was higher in plants derived from hydro-primed (HP) seeds when compared to NP, osmoprimed (KNO₃P), and hormonal primed (GA₃P) ones. Under control and 100 mM NaCl treatment, malondialdehyde (MDA) content and EL did not show any correlation with activities of gaiacol peroxidase (GPX) and catalase (CAT), but did with the increase in reduced ascorbate (AsA) and total ascorbate contents. The results indicated that plants derived from HP seeds exhibited higher adaptive potential under salinity stress. Our findings suggest that a hydropriming technique can be used as a simple commercial approach to alleviate the effects of NaCl induced stress in lettuce plants.