Visible Toxicity Symptoms Research Articles

697 (PS 5) MICRONUTRIENT TOXICITY SYMPTOMS IN BUFFALOGRASS

The effect of increasing micronutrient levels on buffalograss (Buchloe dactyloides) was investigated. Seedling plants established in peat-lite mix in 10-cm pots were irrigated with solutions containing 0.5, 1, 2, 4, 6, 8, or 12 mM of boron (B), chloride (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), or zinc (Zn). The control solution contained (in μM): 20 B, 0.5 Cu, 40 Fe, 10 Mn, 0.5 Mo and 4 Zn. A standard macronutrient concentration was used for all treatment solutions. Boron and Mo induced visual toxicity symptoms more readily than other micronutrients. Boron toxicity was characterized by chlorosis often accompanied by bleached leaf tips, while Mo toxicity resulted in leaf necrosis. The lowest levels that induced foliar toxicity symptoms were: 0.5 mM B, 2 mM Cu, 4 mM Fe, 6 mM Mn, 1 mM Mo, and 4 mM Zn. Chloride did not induce foliar abnormalities in the concentration range tested. Biomass yield was reduced when the nutrient solution contained 2 mM B, 8 mM Cu, 2 mM Mo, or 12 mM Zn. Elevated levels of Cl, Fe and Mn did not alter dry matter yield. Tissue concentrations of micronutrients were also determined.

INFLUENCE OF INCREASED ROOT MEDIA PHOSPHORUS LEVELS IN POINSETTIA PRODUCTION

Acidification of the irrigation water with phosphoric acid is a common practice to avoid nutrient deficiencies/toxicities from alkaline root media. It has been suggested high phosphorus levels could cause phosphorus toxicity. Euphorbia pulcherrima Willd. cultivars Supjibi and Celebrate 2 cuttings were potted on June 6, 1991 in a root medium of peat, perlite and soil (40:40:20 by volume) amended with N, K, Ca and micro-nutrients, plus six phosphorus (0-40-0) rates of .89, 1.78, 3.55, 7.11, 10.67, and 14.22 kg/meter3. Foliar samples were analyzed for NH4, P, and K every two weeks after the start of short days. Root media samples were also collected and analyzed pH, SS and NO3, P, K and NH4. Bract diameter, bract edge burn, days to anthesis, and plant height were recorded at anthesis. Media P levels increased as the phosphorus rate increased, but a significant treatment*harvest interaction for media P was observed. There was decreased bract size and increased incidences of bract edge burn as phosphorus rate increased. Root media P levels did not affect the levels of other nutrient elements in the foliar samples. No visual symptoms of phosphorus toxicity was observed except for bract edge burn at anthesis.

MICRONUTRIENT TOXICITY IN PETUNIA HYBRIDA

Foliar micronutrient toxicity symptoms of Petunia hybrida `Ultra Crimson Star' were induced by elevated levels (from 0.25 to 6 mM) of boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo) and zinc (Zn) in the nutrient solution. Foliar toxicity symptoms of most micronutrients (except Fe) were characterized by leaf yellowing, interveinal chlorosis, and marginal necrosis. Mo toxicity was most severe. Leaf abnormality was not induced by Fe in the concentration range tested. Visible foliar toxicity symptoms developed when nutrient solution contained 5.4, 32, 28, 24, and 16 mg· liter-1, respectively, of B, Cu, Mn, Mo and Zn. Biomass yield was reduced when the fertilizer solution contained (in mg· liter-1): 22 B, 64 Cu, 335 Fe, 28 Mn, 24 Mo, and 33 Zn.

Influence of a high Mn supply on Norway spruce (Picea abies (L.) Karst.) seedlings in relation to the nitrogen source.

Effects of 3, 25, 100, 200 and 800 microM Mn on biomass and pigment, starch and nitrate concentrations were studied in Norway spruce (Picea abies (L.) Karst.) seedlings grown with either NO(3) (-) or NH(4) (+) as the sole nitrogen source. After 77 days of exposure to 800 microM Mn, shoot growth had ceased in about 50% of the seedlings independently of the N source. Despite high Mn concentrations in roots and shoots of the Mn-treated seedlings, no visible symptoms of Mn toxicity were evident. The rate of root elongation was decreased by treatment with >/= 200 microM Mn when N was supplied as NO(3) (-), but not when it was supplied as NH(4) (+). This difference could be attributed to the higher Mn concentrations in root tips of the NO(3) (-)-grown seedlings compared with the NH(4) (+)-grown seedlings. In Mn-treated seedlings, the concentration of Mg, and to a lesser extent that of Ca, decreased. Depletion of these elements might account for the observed growth depression. Potassium concentrations were similar in the control and Mn-treated seedlings. Treatment of seedlings with 800 microM Mn for 50 days led to several physiological changes: starch accumulated, the concentrations of nitrate and phenolic compounds increased, pigment concentrations decreased, and in vivo nitrate reductase activity in roots was reduced.

Glyphosate residues in a sandy soil affect tomato transplants

Glyphosate residues in a loamy sand soil were suspected of damaging transplanted tomatoes at Gosford in 1990. Field and glasshouse experiments were conducted to determine whether phytotoxic residues of glyphosate persist in this soil type and, if so, under what conditions. In the glasshouse experiment, visible symptoms of glyphosate toxicity occurred in tomato seedlings transplanted into soil that was sprayed 1, 5 or 15 days earlier with glyphosate (360 g a.i.L) at 4 L productha. Glyphosate also reduced plant dry weight (16 days after transplanting), but only where soil nutrient deficiencies were corrected after transplanting. In this case, seedlings transplanted 15 days after spraying suffered an average reduction in dry weight of 57%. Greater reductions in dry weight occurred where superphosphate (43 kg Pha) was mixed through soil before spraying (75 v, 35% reduction). In the field, glyphosate residues reduced plant dry weight 16 days after transplanting, even when transplanting followed spraying by up to 9 days, and possibly as many as 30. At 9 days, reductions of 50, 74 and 78% were recorded with glyphosate (360 g a.i./L) applied at 2, 4 and 8 L/ha, respectively. Effects of glyphosate on fruit yield were significant (P<0.05), but much smaller than effects on earlier plant dry weights. The phytotoxicity of glyphosate residues in this loamy sand appears to result from a combination of inherently low P sorption capacity and application of superphosphate, leading to low adsorption of glyphosate by soil. This may be exacerbated when dry conditions occur between application and planting. On the present evidence, a plant-back period of 3 weeks could be considered safe when transplanting tomatoes into this sandy soil, provided some mixing of soil occurs at transplanting. It is recommended that farmers perform a simple bioassay to confirm safety.

MICRONUTRIENT TOXICITY IN SEED GERANIUM PELARGONIUM × HORTORUM BAILEY

Micronutrient toxicity symptoms of seed geranium (Pelargonium × hortorum Bailey) `Ringo Scarlet' were experimentally induced by using 9 different concentrations of B, Cu, Fe, Mn, Mo and Zn in the fertilizer solution. Plants of 3-4 true leaf stage grown in peat-lite mix were constantly fed for 5 weeks with nutrient solutions containing 0.25, 0.5, 1, 2, 3, 4, 5, and 6 mM of each micronutrient. The control solution contained 20 uM B, 0.5 uM Cu, 10 uM Fe, 10 uM Mn, 0.5 uM Mo and 4 uM Zn. Visible foliar toxicity symptoms developed when the nutrient solution contained 2, 0.5, 5, 1, 0.25, and 0.5 mM, respectively, of B, Cu, Fe, Mn, Mo, and Zn. Reduction in dry matter yield was evident when 1 mM B, 2 mM Cu, 3 mM Fe, 2 mM Mn, 0.5 mM Mo, and 1 mM Zn were used in the fertilizer solution. Leaf chlorophyll contents decreased as Cu and Mn levels increased. Elevated levels of Fe increased tissue chlorophyll contents.

Pharmacological Studies on Aerial Parts of Calotropis Procera

The decoction of the aerial part of Calotropis procera is commonly used in Saudi Arabian traditional medicine for the treatment of variety of diseases including fever, joint pain, muscular spasm and constipation. The present investigation was undertaken to confirm its claimed activity in traditional medicine. The ethanol extract of the plant was tested on laboratory animals for its antipyretic, analgesic, anti-inflammatory, antibacterial, purgative and muscle relaxant activities. The results of this study showed a significant antipyretic, analgesic and neuromuscular blocking activity. On smooth muscle of guinea pig ileum, the extract produced contractions which was blocked by atropine supporting its use in constipation. The extract failed to produce significant anti-inflammatory and antibacterial activities. Our phytochemical studies on the aerial parts of C. procera showed the presence of alkaloids, cardiac glycosides, tannins, flavonoids, sterols and/or triterpenes. However, the chemical constituents responsible for the pharmacological activities remains to be investigated. The safety evaluation studies revealed that the use of extract in single high doses (up to 3 g/kg) does not produce any visible toxic symptoms or mortality. However, prolong treatment (90 days) causes significantly higher mortality as compared to control group.

TOXICITY SYMPTOMS OF MICRONUTRIENTS COPPER, MAGNESIUM AND ZINC FOR SELECTED BEDDING PLANTS

Toxicity symptom of micronutrients copper, magnesium and zinc were investigated for geranium, marigold, vinca and zinnia. Plants were grown in peat-lite mix in 11 cm plastic pots and watered with nutrient solutions containing 0.05, 0.5, 1, 5, 10 mM concentrations of Cu2+, Mg2+ and Zn2+. In most species, the concentrations of these micronutrients higher than 5 mM greatly reduced plant growth and induced stem and foliar toxicity symptoms. Toxic levels of Cu2+ and Zn2+ reduced plant and leaf sizes without producing leaf spots in all species tested. Toxicity symptom of Mn2+ were characterized by numerous chlorotic or brown leaf spots. Visual leaf toxicity symptoms of these 3 micronutrients in each species are illustrated.

Boron utilization by potato in nutrient cultures and in field plantings

Abstract Analysis of soil and plant tissue for boron (B) is routine, but more information is needed to clarify the interpretations of test results as a basis for B fertilization of potato (Solarium tuberosum L.). Experiments were conducted in nutrient cultures and in the field to relate the utilization of B by potato plants to visual symptoms of deficiency and toxicity. Without added B the nutrient cultures produced B‐deficient potato plants, but the field plots with 0.3 to 0.4 mg of hot water soluble B/kg of soil did not. Plant shoots from nutrient cultures had a minimum of 13 mg B/kg as compared with plants in field plots with 30 mg B/kg in vines. Concentrations to 50 mg B/kg of dry matter were obtained in plant shoots from nutrient cultures with 1 mg B/L added and in field‐grown plants fertilized with 2.2 kg B/ha. Toxicity to B appeared or was eminent from either adding 3 mg B/L or more to nutrient solutions or 4.5 kg B/ha or more to the field plots. These results suggest the feasibility of developing ...

Cadmium bioavailability to Nicotiana tabacum L., Nicotiana rustica L., and Zea mays L. grown in soil amended or not amended with cadmium nitrate

Mature (flowering) tobacco (Nicotiana tabacum cv. PBD6, Nicotiana rustica cv. Brasilia) and maize (Zea mays cv. INRA 260) plants were grown in an acid sandy-clay soil, enriched to 5.4 mg Cd kg−1 dry weight soil with cadmium nitrate. The plants were grown in containers in the open air. No visible symptoms of Cd toxicity developed on plant shoots over the 2-month growing period. Dry-matter yields showed that while the Nicotiana spp. were unaffected by the Cd application the yield of Z. mays decreased by 21%. Cd accumulation and distribution in leaves, stems and roots were examined. In the control treatment (0.44 mg Cd kg−1 dry weight soil), plant Cd levels ranged from 0.4 to 6.8 mg kg−1 dry weight depending on plant species and plant parts. Soil Cd enrichment invariably increased the Cd concentrations in plant parts, which varied from 10.1 to 164 mg kg−1 dry weight. The maximum Cd concentrations occurred in the leaves of N. tabacum. In N. rustica 75% of the total Cd taken up by the plant was transported to the leaves, and 81% for N. tabacum irrespective of the Cd level in the soil. In contrast, the Cd concentrations in maize roots were almost five times higher than those in the leaves. More than 50% of the total Cd taken up by maize was retained in the roots at both soil Cd levels. The Cd level in N. tabacum leaves was 1.5 and 2 times higher at the low and high Cd soil level, respectively, than that in N. rustica leaves, but no significant difference was found in root Cd concentrations between the two Nicotiana spp.

The effects of oxides of nitrogen and carbon dioxide enrichment on photosynthesis and growth of lettuce (Lactuca sativa L.).

The response of glasshouse crops to the nitrogen oxide pollutants which may be generated during enrichment with O2 has been studied in controlled environments. Lettuce (Lactuca sativa L. cv. Ambassador) was grown in air containing either low CO2 , (380μmol mol-1 ), high CO2 , (1200 μmol mol -1 ), or high CO2 plus oxides of nitrogen? (NOx )- Carbondioxide enrichment increased the rate of emergence and expansion of leaves and the growth of Young plants. Addition of NOx (2μmol mol-1 NO and c. 0.5 μmol mol-1 NO2 ) to CO2 -enriched air significantly reduced the yield, compared with the 'clean, high CO2 treatment, without producing visible symptoms of toxicity. Fumigation of single plants in high CO2 , with NOx rapidly inhibited photosynthesis per unit leaf area. This did not appear to be due to a reduction in stomatal conductance. Removal of NOx from the atmosphere caused a rapid and complete recovery in the rate of photosynthesis. Studies were made of the effects of growing Plants for long periods in atmospheres containing high CO2 and NOx on the photosynthetic capacity of single leaves when measured in NOx -free air. The decrease in photosynthetic rate as the fourth leaf aged occurred earlier in plants grown in CO2 -enriched air than in those from the low CO2 treatment. Leaves which developed in the CO2 -enriched air containing NOx did not suffer any long-term damage to photosynthetic activity in comparison with those of the 'clean' high CO2 . In mature leaves the principal long-term effect of enrichment (with or without NOx was to reduce the rate of photosynthesis in saturating CO2 . In contrast, there was less effect on the rate of Photosynthesis in low CO2 . The absence of a long-term effect of NOx , on the photosynthetic capacity suggested that photosynthesis by the lettuce crop will be inhibited only during the transient periods of NOx accumulation in the glasshouse.

A microculture method for assessing nutrient uptake II. The effect of temperature on manganese uptake and toxicity in potato shoots

Abstract Using standard microculture techniques for propagating potato (Solanum tuberosum L.cv. Norland), the effects of three temperature (20, 25, 30 °C) and two phosphate treatments (1.25, 2.5 mM) on the expression of Mn toxicity were investigated. Foliar yields were maximal at low temperature, but phosphate increased yield of high temperature treatments, particularly at high Mn. The uptake of Mn and severity of visual symptoms of toxicity increased with P level. A reduction in yield due to high temperature also brought about high Mn concentrations and an increase in Mn toxicity symptoms. Lateral buds developed rapidly under high Mn resulting in short highly branched shoots at high temperature. The increased severity of Mn toxicity at high temperature was attributed to an interaction between growth rate and Mn tolerance.

Carbohydrate metabolism and phosphorus/salinity interactions in wheat (Triticum aestivum L.)

Foliar inorganic ion and carbohydrate concentrations were determined in wheat plants treated with factorial combinations of phosphorus fertilizer and NaCl in a glasshouse experiment. Growth reductions and visual symptoms of salt toxicity were minimized when phosphorus nutrition was adequate, and were intensified by phosphorus deficiency. Foliar sodium and chloride accumulated up to 4.0–5.5% d.w. with salinity treatment. However, ionic concentrations within corresponding leaves or distributions between leaves of plants with different phosphorus treatments were not influenced by phosphorus treatment and had no relationship to the severity of salt toxicity symptoms. This suggests that phosphorus deficiency reduced the cellular tolerance for ion accumulation. A combination of phosphorus deficiency and salinity induced an accumulation of foliar starch and sucrose despite substantial reductions in net CO2 assimilation rates. This accumulation did not occur if phosphorus nutrition was adequate, which is consistent with the roles of phosphorus in carbohydrate metabolism. It is proposed that adequate phosphorus nutrition is essential for effective ion compartmentation by contributing to efficient carbohydrate utilization in salt-stressed wheat.

Early Inhibition of Photosynthesis during Development of Mn Toxicity in Tobacco

Early physiological effects of developing Mn toxicity in young leaves of burley tobacco (Nicotiana tabacum L. cv KY 14) were examined in glass-house/water cultured plants grown at high (summer) and low (winter) photon flux. Following transfer of plants to solutions containing 1 millimolar Mn(2+), sequential samplings were made at various times for the following 9 days, during which Mn accumulation by leaves increased rapidly from approximately 70 on day 0 to approximately 1700 and approximately 5000 microgram per gram dry matter after 1 and 9 days, respectively. In plants grown at high photon flux, net photosynthesis declined by approximately 20 and approximately 60% after 1 and 9 days, respectively, and the onset of this decline preceded appearance (after 3 to 4 days) of visible foliar symptoms of Mn toxicity. Intercellular CO(2) concentrations and rates of transpiration were not significantly affected; moreover, the activity of the Hill and photosystem I and II partial reactions of chloroplasts remained constant despite ultimate development of severe necrosis. Though the activity of latent or activated polyphenol oxidase increased in parallel with Mn accumulation, neither leaf respiration nor the activity of catalase [EC 1.11.1.6] and peroxidase [EC 1.10.1.7] were greatly affected. These effects from Mn toxicity could not be explained by any changes in protein or chlorophyll abundance. Additionally, they were not a consequence of Mn induced Fe deficiency. Therefore, inhibition of net photosynthesis and enhancement of polyphenol oxidase activity are early indicators of excess Mn accumulation in tobacco leaves. These changes, as well as leaf visual symptoms of Mn toxicity, were less severe in plants cultured and treated at low photon flux even though the rates of leaf Mn accumulation at high and low photon flux were essentially equivalent.

Response of Blueberry Species to Excessive Manganese

Abstract The response of blueberries (Vaccinium spp.) to added Mn was studied in soil, solution, and sand cultures. Weekly additions of up to 0.8 mg Mn to Berryland sand soil (4.3 kg/pot) for 7 months produced the most growth in highbush blueberries, and additions of 6.4 mg Mn/week resulted in growth reductions but no visual toxicity symptoms. Solution culture- (800 ml/bottle) grown ‘Blueray’ highbush blueberries tolerated Mn additions up to 96 μg·ml−1 without significant growth reductions. Under similar conditions, a lowbush clone grew best at high added Mn and had higher foliar Mn concentrations than did ‘Blueray’, the rabbiteye cultivar ‘Tifblue’, or a selection of Vaccinium elliotti Chapman. Lowering solution Ca, Mg, and NO3 levels sharply increased foliar or stem Mn concentrations of all species. Growth of three genetically diverse hybrid blueberry progenies were not signficiantly affected by relatively high levels of applied Mn or Al when grown in sand culture. Increasing Al had a greater effect on increasing root Mn concentrations than did an increase in Mn levels. There were no visual Mn toxicity symptoms expressed in any of the three media from excessive Mn levels.

Nutrição mineral de seringueira: IX. alumínio no substrato afetando o desenvolvimento, a sintomatologia de toxicidade e a concentração em seringueira (Hevea spp)

Com o propósito de comparar os efeitos de doses crescentes de alumínio sobre o desenvolvimento de plantas de seringueira e distinguir o grau de tolerância do grau de toxicidade desse elemento sobre a planta, conduziu-se um experimento usando-se separadamente solução nutritiva de BOLLE-JONES (1957) e soluções de doses de alumínio que se constituíram de 0, 5, 10, 15, 20 e 25ppm de alumínio, em que as plantas passaram vinte e quatro horas na solução nutritiva (sem alumínio) e vinte e quatro horas nas soluções de alumínio correspondentes aos tratamentos acima. As plantas foram coletadas e separadas em raíz, caule, folhas dos verticilos inferiores e folhas do último verticilo. Determinaram-se os acúmulos de alumínio e as concentrações em função das doses de alumínio em cada parte da planta. Os sintomas visuais de toxicidade de alumínio foram identificados e descritos. Concluiu-se que: - o desenvolvimento de plantas de seringueira é afetado a partir de 15ppm de alumínio na solução; - Sinais de excesso de alumínio aparecem primeiro no sistema radicular. Na parte aérea, é difícil identificar efeito tóxico de alumínio dado a sua semelhança com sintomas visuais de deficiência de fósforo; - A seringueira é planta acumuladora e tolerante a presença de concentrações de alumínio no substrato inferior a 15ppm. Níveis superiores de alumínio provocam distúrbios nutricionais na planta.

Callose deposition in leaves of cowpea (Vigna unguiculata [L.] Walp.) as a sensitive response to high Mn supply

First macroscopic visible symptoms of Mn toxicity in cowpea (Vegna unguiculata [L.] Walp.) plants grown in solution culture were dark brown spots on the older leaves. Close to these spots, large quantities of substances which fluorescence with aniline blue were deposited, indicating formation of (1,3)-β-glucan (callose). Callose formation in the leaf epidermis was a more sensitive indicator of Mn toxicity than the appearance of macroscopic symptoms, or the Mn concentration in the leaf.

Silicon interactions with manganese and aluminum toxicity in sorghum

Abstract Silicon fertilization has been shown to alleviate Mn and Al toxicities in some plants. Experiments were conducted to assess the role of different Si levels on the alleviation of Mn and Al toxicity symptoms and on dry matter yields of sorghum [Sorghum bicolor (L.) Moench] grown in nutrient solutions with toxic levels of Mn and Al. Silicon concentration as high as 1780 μM had no detrimental effects on dry matter yields. At high Si levels (2670 and 3560 μM), shoot dry matter yields decreased, but root dry matter yields did not. Plants grown with 3600, 5400, and 7200 μM Mn showed marked visual toxicity symptoms in shoots but no effects on roots, even though root dry matter yield decreased more than shoot dry matter yield. The toxicity symptoms and the dry matter yield reductions caused by 3600 and 5400 μM Mn were partially alleviated by 1780 and 3560 μM Si, whereas no Si level overcame the severe effects induced by 7200 μM Mn. Plants grown with high Al (296 μM) had reduced root dry matter yields. Sil...

Toxidez de alumínio e manganês em sorgo sacarino (Sorghum bicolor (L.) moench): I. Efeitos do silicato e do carbonato de cálcio em solo podzólico vermelho amarelo var. laras

Foram determinados produção de matéria seca de raízes, colmos e folhas e teores de P, Ca, Mg, K, Al, Mn e Fe de três cultivares de sorgo sacarino (Br500, Br602 e Ample-H-OK) crescendo em solo Podzólico Vermelho Amarelo Var. Laras, em presença e ausência de corretivos da acidez do solo (calcário e silicato). Ocorreram diferenças genotípicas na resposta aos corretivos. O melhor tratamento para a produção de matéria seca das folhas não foi necessariamente o melhor para a produção de matéria seca dos colmos. O calcário propiciou efeitos relativos melhores que o silicato na promoção do crescimento dos cultivares. O cultivar Br500 apresentou a melhor resposta ao calcário e Br602 ao silicato. A melhor produção de matéria seca de colmos do sorgo sacarino, proporcionado pela aplicação de corretivos, deveu-se principalmente à redução da saturação em alumínio e ao aumento da CTC efetiva, do Ca trocável e do pH do solo. O calcário promoveu a redução nos teores foliares de todos os elementos analisados, inclusive Al e Mn. O silicato acarretou aumentos nos teores de Ca, Mg, K, P e Al. Não foram constatados sintomas visuais de toxicidade de Mn nos níveis presentes, embora a produção de matéria seca total tenha sido afetada. Os cultivares foram afetados pelo Al trocável do solo na seguinte ordem decrescente: Ample-H-OK >Br602 > Br500.

Soil and Foliar Application of Magnesium Compounds for the Control of Magnesium Deficiency in ‘Shamouti’ Orange Trees

Abstract Band application of MgCl2·6H2O under the tree canopy of ‘Shamouti’ orange [Citrus sinensis (L.) Osbeck] trees significantly increased leaf Mg and Cl concentration. MgSO4 and MgO were not effective. Fertigation with MgCl2·6H2O was less efficient than band application and was not superior to foliar application of Mg(NO3)2·6H2O for increasing leaf Mg concentrations. In spite of high Cl concentration of the leaves, no visible toxicity symptoms were observed.