PRODUCTION AND QUANTIFICATION OF METHYL KETONES IN WILD TOMATO ACCESSIONS

Production of methyl ketones as naturally occurring insecticides from wild tomato accessions is explored in this study. Density of two glandular trichomes (type IV and type VI) on the leaves of six wild tomato accessions of Lycopersicon hirsutum f. glabratum (Mull); three accessions of L. hirsutum f. typicum (Humb & Bonpl.); two accessions of L. pennellii Corr. (D'Arcy); and density of type VI glandular trichomes of the commercial tomato Lycopersicon esculentum cv. Fabulous are reported. Densities of type IV and VI glandular trichomes varied among the accessions tested. Type IV trichomes occurred at much higher densities than type VI. Over all accessions and counting trichome densities on both abaxial and adaxial leaflet surfaces, type IV densities averaged 96,378 trichomes.g^?1 leaflets while type VI densities averaged 67,350 trichomes.g^?1 leaflets. Concentrations of four methyl ketones (2-tridecanone, 2-dodecanone, 2-undecanone, 2-pentadecanone) were determined per unit leaf surface area (mm²) and per g fresh leaflets. Concentrations of total methyl ketones ranged from 81.3 μg. g^?1 fresh leaflets on L. esculentum cv. Fabulous to 5.5 mg. g^?1 on L. hirsutum f. glabratum (PI 134417). Two methyl ketones, 2-undecanone and 2-tridecanone, predominated trichome secretions in five of the L. hirsutum f. glabratum accessions tested (PI 251304, PI 126449, PI 134417, PI 134418, and LA 407).     

Natural Products: Seasonal Variation in Trichome Counts and Contents in Lycopersicum hirsutum f. glabratum

Abstract

Wild tomato leaves possess a pest-resistance mechanism in their glandular trichomes and the exudates they produce. Type IV and VI glandular trichomes on the leaves of five wild tomato accessions of Lycopersicum hirsutum f. glabratum (PI 126449, PI 134417, PI 134418, PI 251304, and LA 407) grown under greenhouse conditions were counted. Major chemical compounds from glandular leaf trichomes of the accessions tested were extracted, purified, and quantified at different periods during the growing seasons by gas chromatography (GC) and mass spectrometry (GC/MS). The toxicity of two methylketones (2-undecanone and 2-tridecanone), the major constituents of the accessions tested, to adults of the sweetpotato whitefly, Bemisia tabaci (Gennadius) and fourth instar larvae of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), was determined using no-choice bioassays. 2-undecanone caused 80% mortality of the fourth instar larvae of the CPB at the highest concentration tested (100 mg 2-undecanone mL^{? 1} of acetone) while 2-tridecanone caused 72% mortality of whiteflies at 20 mg 2-tridecanone mL^{? 1} of 65% ethanol. The concentration of 2-undecanone and 2-tridecanone on the leaves of each of the five accessions of L. hirsutum f. glabratum and the mass spectra of 2-undecanone and 2-tridecanone are presented. Overall, the concentration of 2-undecanone on the leaves was significantly higher than 2-tridecanone. Concentration of the two methylketones varied among accessions and sampling season. Plants produced the highest concentration of 2-undecanone during the month of August. On average, each plant of accession PI 251304 provided 354 g fresh leaves (averaging about 52,353 cm² exposed leaf surface area) and produced 32.5 and 8.7 mg of 2-undecanone and 2-tridecanone, respectively. L. hirsutum f. glabratum accessions may become a valuable source of natural products, which could minimize reliance on synthetic pesticides.     

Micronucleus frequency in sheep lymphocytes after in vitro exposure to fungicide tolylfluanid

The fungicide tolylfluanid (N - dichlorofluoromethylthio-N′, N - dimethyl - N - p - tolylsulfamide), was investigated by cytokinesis-block micronucleus assay. Tolylfluanid at the lowest concentration (1 × 10^{? 6}mol L^{? 1})did not influence significantly the frequency of micronuclei in sheep lymphocyte cultures in comparison with control (32.33 ± 3.51/1000 binucleated cells versus 30.33 ± 2.82/1000 binucleated cells in dimethylsulfoxide (DMSO) control, P = 0.44). Higher tolylfluanid concentrations (1 × 10^{? 4} and, 1 × 10^{? 5} mol L^{? 1}) resulted in a significant dose-dependent increase in the number of micronuclei in comparison with control (74.00 ± 13.00/1000 binucleated cells and 52.67 ± 10.12/1000 binucleated cells versus 30.33 ± 2. 82/1000 binucleated cells in DMSO control, P = 0.005 and 0.02, respectively, ANOVA followed by Tukey test P < 0.05). Many of the treated cells also possessed multiple micronuclei. Tolylfluanid did not affect the nuclear division index at all treatment concentrations. Our in vitro results thus demonstrate that tolylfluanid had a significant genotoxic effect at only the highest concentration tested.     

Introduction to the Air & Waste Management Association's 29th Annual Critical Review

Abstract

On-road mobile sources contribute substantially to ambient air concentrations of the carcinogens 1,3-butadiene, benzene, and polycyclic aromatic hydrocarbons (PAHs). The current study measured benzene and 1,3-butadiene at the Baltimore Harbor Tunnel tollbooth over 3-hr intervals on seven weekdays (n = 56). Particle-bound PAH was measured on a subset of three days. The 3-hr outdoor 1,3-butadiene levels varied according to time of day and traffic volume. The minimum occurred at night (12 a.m.–3 a.m.) with a mean of 2 µg/m³ (SD = 1.3, n = 7), while the maximum occurred during the morning rush hour (6 a.m.–9 a.m.) with a mean of 11.9 µg/m³ (SD = 4.6, n = 7). The corresponding traffic counts were 1413 (SD = 144) and 16,893 (SD = 692), respectively. During the same intervals, mean benzene concentration varied from 3 µg/m³ (SD = 3.1, n = 7) to 22.3 µg/m³ (SD = 7.6, n = 7). Median PAH concentrations ranged from 9 to 199 ng/m³. Using multivariate regression, a significant association (p < 0.001) between traffic and curbside concentration was observed. Much of the pollutant variability (1,3-butadiene 62%, benzene 77%, and PAH 85%) was explained by traffic volume, class, and meteorology. Results suggest >2-axle vehicles emit 60, 32, and 9 times more PAH, 1,3-butadiene, and benzene, respectively, than do 2-axle vehicles. This study provides a model for estimating curbside pollution levels associated with traffic that may be relevant to exposures in the urban environment.     

Toxicity of new pyrethroid in pest insects Asciamonuste and Diaphania hyalinata,predator Solenopsis saevissima and stingless bee Tetragonisca angustula

There is increasing demand for new products for vegetable pest management. Thus, the aim of this study was to assess the toxicity of pyrethroids with acid moiety modifications to measure the insecticidal activity of these compounds on the lepidopteran vegetable pests Diaphania hyalinata (L.) (Lepidoptera: Pyralidae) and Asciamonuste (Latreille) (Lepidoptera: Pieridae) and evaluate their selectivity for the predatory ant Solenopsis saevissima (F. Smith) (Hymenoptera: Formicidae) and pollinator Tetragonisca angustula (Latreille) (Hymenoptera: Apidae: Meliponinae). Racemic mixtures of five new pyrethroids (30 µg molecule mg^?1 insect body weight) resulted in high (100%) and rapid (stable LD₅₀ after 12 h) mortality in D. hyalinata and A. monuste. In A. monuste, the trans-pyrethroid [12] isomer showed similar toxicity to permethrin. For D. hyalinata, the trans-pyrethroid [9] isomer and cis-pyrethroid [10] isomer were as toxic as permethrin. Due to their low selectivity, these new pyrethroids should be applied on the basis of ecological selectivity principles to minimize impacts on nontarget organisms S. saevissima and T. angustula.     

The relationship between metal composition,phenolic acid and flavonoid content in Imleria badia from non-polluted and polluted areas

ABSTRACT

The aim of this study was to determine the elemental composition, phenolic content and composition and antioxidant properties of Imleria badia (Fr.) Vizzini (former names Boletus badius (Fr.) Fr., and Xerocomus badius (Fr.) E.-J. Gilbert) fruiting bodies collected from sites with different levels of pollution. Imleria badia was relatively tolerant to soil contamination with toxic elements and was able to grow in As, Cd, Hg and Pb concentrations exceeding 15, 2.9, 0.4 and 77 mg kg^?1, respectively. The concentration of elements in soil was reflected in the element content in I. badia. The fruiting bodies from polluted sites exhibited significantly higher content of all the analyzed elements. Among 21 individual phenolic compounds only protocatechiuc and caffeic acids, and quercetin were determined in fruiting bodies of I. badia. The differences between the concentration of the quantified phenolic compounds and the total flavonoid content in fruiting bodies of I. badia from unpolluted and polluted sites were not significant. However, the greatest total phenolic content was found in fruiting bodies from the polluted areas. The antioxidative capacity of mushrooms collected from heavily polluted sites was lower than those growing in unpolluted areas. The concentrations of some metals in soil and fruiting soil were positively correlated with phenolic content and IC₅₀.     

Summary of efficacy evaluations using aerially applied Gypchek® against gypsy moth in the U.S.A.

Abstract

Gypchek^®, the gypsy moth (Lymantria dispar L.) nucleopolyhedrosis virus product, is manufactured by the United States Department of Agriculture (USDA) Forest Service, and Animal and Plant Health Inspection Service under controlled conditions in a laboratory strain of gypsy moth larvae. Gypchek was registered with the U.S. Environmental Protection Agency in 1978 as a general use pesticide to control gypsy moth. This product has been the subject of intense research and development targeted toward maximizing efficacy while minimizing the cost of production and application. The current Gypchek tank mix is applied at 1.25 × 10¹²occlusion bodies (OB's) per hectare for each of two applications (3‐days apart) at 18.7 litres/ha per application.     

Effects of cadmium,zinc, copper and manganese on hepatic parenchymal cell gluconeogenesis

Abstract

The effects of divalent cations on gluconeogenesis in enzy‐matically isolated rat hepatic parenchymal cells were examined. Cadmium, zinc and copper decreased glucose production from lactate (10 mM). However, manganese at 0.05 to 1.0 mM levels stimulated gluconeogenesis by the cells and reduced the effects of the Cd⁺², Zn⁺² and Cu⁺² on gluconeogenesis. The results indicate that under these in vitro conditions the cations altered an aspect of hepatic function—gluconeogenesis from lactate.     

Effect of Monosodium Methanarsonate Application on Cuticle Wax Content of Cocklebur and Cotton Plants

Leaf cuticle waxes were extracted from monosodium methanearsonate (MSMA)-resistant (R) and -susceptible (S) common cocklebur (Xanthium strumarium L.) and cotton (Gossypium hirsutum L.) plants at 0, 3, 5, and 7 days after treatment (DAT) following 1× and 2× MSMA applications. Wax constituents were analyzed by gas chromatography (GC) with flame ionization detection and compared to alkane and alcohol standards of carbon lengths varying from C21 to C30. Differences in waxes were calculated and reported as change per ng mm^2–1. Tricosane (C23) was found to increase following MSMA applications. All other alkanes decreased by 7 DAT, with some showing a linear effect over time in the R-cocklebur. Alcohol constituents were also observed to decrease by 7 DAT. Total arsenic in the extracted wax fraction was determined, with greatest quantities detected in the R-cocklebur. Wax changes are not believed to play a role in cotton tolerance, since changes in cuticle concentrations were minimal. Cocklebur resistance to MSMA is not due to cuticle constituents; the wax changes are a secondary effect in response to herbicide application.     

Microwave synthesis and antifungal evaluations of some chalcones and their derived diaryl-cyclohexenones

Microwave irradiation (MWI) of acetophenones and substituted benzaldehydes in water resulted in a “green-chemistry” procedure for the preparation of chalcones (1-14), through base catalyzed Claisen-Schmidt condensation reaction, in good yields. Further 3,5-diaryl-6-carbethoxy-2-cyclohexen-1-ones (1a-14a) were prepared through base catalyzed cyclocondensation of above chalcones with ethylacetoacetate using MWI as the energy source and silica as support. Out of fourteen cyclohexenones, ten (1a, 4a, 5a, 6a, 7a, 9a, 10a, 11a, 12a and 13a) are reported for the first time in literature. The synthesized compounds were characterized using various spectroscopic techniques, viz. (¹H NMR and IR) and screened for their antifungal activity in vitro against Sclerotium rolfsii and Rhizoctonia solani by poisoned food technique. The compounds tested were found to be active against R. solani whereas against S. rolfsii, moderate activity was observed, as evident from LC₅₀ values. The most potent compounds against R. solani were 1-(4-Fluoro-phenyl)-3-phenyl-propenone (13) and 1,3-Diphenyl-propenone (14) having LC₅₀ values of 2.36 and 2.49 mgL^{? 1} respectively (LC₅₀ of Hexaconazole = 1.12 mgL^{? 1}) and against S. rolfsii 3-(4-Fluoro-phenyl)-5-(3-nitro-phenyl)-6-carbethoxy-2-cyclohexen-1-one (12a) was most active having LC₅₀ value of 285 mgL^{? 1}compared to Hexaconazole (LC₅₀ = 1.27 mgL^{? 1}).     

Synthesis and antifungal activity of 2H-1,4-benzoxazin-3(4H)-one derivatives

A series of 2-alkyl-2H-1,4-benzoxazin-3(4H)-ones (4a-l) was easily synthesized by two-step process involving O-alkylation of 2-nitrophenols with methyl 2-bromoalkanoates and next “green” catalytic reductive cyclization of the obtained 2-nitro ester intermediates (3a-l). Further, 6,7-dibromo (5a-c) and N-acetyl (6) derivatives were prepared by bromination and acetylation of unsubstituted 2-alkyl-2H-1,4-benzoxazin-3(4H)-ones (4a-c). The novel compounds (3a-l, 4d-l, 5a-c and 6) were fully characterized by spectroscopic methods (MS, ¹H and ¹³C NMR). 2-Alkyl-2H-1,4-benzoxazin-3(4H)-ones (4a-l, 5a-c and 6) were screened for antifungal activity. Preliminary assays were performed using two methods: in vitro against seven phytopathogenic fungi—Botrytis cinerea, Phythophtora cactorum, Rhizoctonia solani, Phoma betae, Fusarium culmorum, Fusarium oxysporum and Alternaria alternata—and in vivo against barley powdery mildew Blumeria graminis. The tested compounds displayed moderate to good antifungal activity at high concentration (200 mg L^?1). The most potent compounds were 2-ethyl-2H-1,4-benzoxazin-3(4H)-one (4a), 2-ethyl-7-fluoro-2H-1,4-benzoxazin-3(4H)-one (4g) and 4-acetyl-2-ethyl-2H-1,4-benzoxazin-3(4H)-one (6), which completely inhibited the mycelial growth of seven agricultural fungi at the concentration of 200 mg L^?1 in the in vitro tests. Moreover, 2-ethyl-2H-1,4-benzoxazin-3(4H)-one (4a) and 4-acetyl-2-ethyl-2H-1,4-benzoxazin-3(4H)-one (6) were also screened for antifungal activity at concentrations of 100 mg L^?1 and 20 mg L^?1. In the concentration of 100 mg L^?1, the N-acetyl derivative (6) completely inhibited the growth of three strains of fungi (F. culmorum, P. cactorum and R. solani), while 2-ethyl-2H-1,4-benzoxazin-3(4H)-one (4a) completely inhibited only R. solani strain. At the concentration of 20 mg L^?1, compound 6 showed good activity only against P. cactorum strain (72%).     

In vitro response of human ovarian cancer cells to dietary bioflavonoid isoquercitrin

Abstract

Isoquercitrin is a dietary bioflavonoid used as a food supplement. We studied the mechanism underlying its effect in human ovarian cancer cells using OVCAR-3 cell line. Viability, survival, apoptosis, release of human transforming growth factor-β1 (TGF-β1) and TGF-β1 receptor, and intracellular reactive oxygen species (ROS) generation by OVCAR-3 cells were examined after isoquercitrin treatment at concentrations 5, 10, 25, 50, and 100?μg mL^?1. AlamarBlue assay revealed that isoquercitrin did not cause any significant change (P?>?0.05) in cell viability as compared to control. Apoptotic assay using flow cytometry did not find any significant change (P?>?0.05) in the proportion of live, dead and apoptotic cells as compared to control. ELISA also showed that the release of human TGF-β1 and TGF-β1 receptor were not significantly (P?>?0.05) affected by isoquercitrin as compared to control. Chemiluminescence assay demonstrated that lower concentrations (5, 10, and 25?μg mL^?1) were able to exhibit beneficial effects by inhibiting the generation of intracellular ROS. In contrast, elevated concentrations of 50 and 100?μg mL^?1 led to oxidative stress (P?相似文献   

Solubility products of six metal‐glyphosate complexes in water and forestry soils,and their influence on glyphosate toxicity to plants

Abstract

The solubility products (K_sp) of 1:1 complexes of glyphosate, [N‐(phosphonomethyl)glycine], with Mg²⁺, Ca²⁺, Mn²⁺, Zn²⁺, Cu²⁺ and Fe³⁺, were determined in buffered (pH 7.0) distilled water, moist Ottawa sand, sandy loam and clay loam soils, each adjusted to 0.02 M with respect to KNO₃. The K_sp values decreased in the order of Mg ? Ca > Mn > Zn > Cu > Fe, regardless of the medium in which they were determined. The constants measured in Ottawa sand were similar to those in water, but those in the forestry soils depended upon the type of metal ion involved. The values for the Mg, Ca, Mn and Zn complexes were about 2 to 3 times lower in sandy loam soil than those in water, but those in clay loam were about 3 to 10 times lower. The K_sp of the Cu and Fe complexes were similar to those in water regardless of the soil type used.

In a bioassay experiment using tomato plants, immersed in the saturated solutions of the complexes or planted in the sand and soils containing saturated solutions of the complexes, no mortality occurred although slight inhibition in growth was observed in all cases. The most soluble complexes of Mg and Ca caused the most reduction in plant height, while the least soluble complex of Fe caused little growth inhibition. The Zn, Cu and Mn complexes caused some growth inhibition depending on their K_sp values. The larger the solubility product, the greater the concentration of glyphosate ion in solution, and the greater the growth inhibition. In a similar experiment using white spruce seedlings, growth inhibition was insignificant over the 12‐d bioassay period.     

Elemental analysis of the edible fruit of Carpobrotus dimidiatus (from Kwazulu-Natal,South Africa) and the influence of soil quality on its elemental uptake

Abstract

Carpobrotus dimidiatus is an indigenous South African medicinal plant species from the Aizoaceae family that bears edible fruit that is consumed for nutritional value. In this study, the elemental distribution in C. dimidiatus fruit and growth soil from fifteen sites in KwaZulu-Natal (South Africa) was determined along with soil pH, soil organic matter and cation exchange capacity, to assess for nutritional value and the effect of soil quality on elemental uptake. The results showed elemental concentrations in fruit to be in decreasing order of Ca (6235–32755?mg kg^?1) > Mg (2250–5262?mg kg^?1) > Fe?>?Mn?>?Zn (20.9–50.6?mg kg^?1) > Cu (3.83–20.6?mg kg^?1) > Pb?>?Cr?>?Cd?>?As?～?Co?～?Ni?～?Se and no potential health risk due to metal toxicity from average consumption. For sites that had high levels of Cd and Pb, bioaccumulation occurred from atmospheric deposition. Concentrations of elements in soil were found to be in decreasing order of Fe (1059–63747?mg kg^?1) > Ca (1048–41475?mg kg^?1) > Mg?>?Mn (9.76–174?mg kg^?1) > Cr (1.55–135?mg kg^?1) > Zn (0.76–58.2?mg kg^?1) > Se?>?Cu?>?Ni?>?Pb?>?Co?>?As?～?Cd with no evidence of heavy metal contamination. This study revealed that the plant inherently controlled uptake of essential elements according to physiological needs and that the concentrations of essential elements in the fruit could contribute positively to the diet.     

Droplet size spectra and deposits of Bacillus thuringiensis aerial sprays,following application at two volume rates over an oak forest

Abstract

Dipel® 8AF, a commercial formulation of Bacillus thuringiensis (B.t.) was sprayed undiluted at 30 BIU in 1.8L/ha over a block B1, and sprayed after dilution with water at 30 BIU in 6.2 L/ha over another block B2 in an oak forest infested with the gypsy moth (Lymantria dispar L.) in southeastern Ontario, Canada. Spray was applied in May 1987 using a Cessna 188 Agtruck aircraft equipped with four Hicronair^® AU4000 atomizers. Droplet sizes were measured at mid‐canopy level of oak trees and at ground level using cylindrical Kromekote® cards. Deposit per unit area was assessed on aluminum oak leaves.

At the lower volume rate of 1.8 L/ha, spray droplets were smaller and droplets/cm² were lower on the cylindrical Kromekote cards in B1 than those obtained in B2 which received the higher volume rate of 6.2 L/ha. The average deposit per unit area of the aluminum oak leaves, expressed in nL of the spray volume per cm² surface area, was also correspondingly lower in B1 than in B2. This was attributed to the higher volume rate of spray application used in B2 than in B1, which resulted in larger droplets and a greater volume deposit/cm² in B2.     

Influx,transport, and accumulation of cadmium in plant species grown at different Cd2+ activities

Abstract

Cadmium (Cd) has no known essential biological function, but it is toxic to plants, animals, and humans. A promising approach to prevent Cd from entering the food chain would be to select and/or create Cd‐accumulating plants to remediate contaminated soils or to develop Cd‐excluding plants to reduce Cd flow from soils into foods. The present study was undertaken to examine the differences in Cd influx, transport, and accumulation among five plant species in relation to plant tolerance to Cd toxicity. Ryegrass (Lolium perenne L.) had the least reduction in dry matter which may be due to its lowest Cd transport rate (TR) to shoots at all Cd levels among the plant species tested. White‐clover (Trifolium repens L.) was the most sensitive species to Cd toxicity, likely because of its highest Cd influx rate (IR) and high TR when plants were grown at low Cd²⁺ activity (≤8 μM). The high tolerance of cabbage (Brassica oleracea var. capitata L.) to moderate Cd toxicity (≤14 μM) appeared to be mainly due to the detoxification of Cd inside plant tissue since it recorded the highest TR and relatively high IR for Cd among the tested species. At Cd²⁺ activities up to 28 uM, the Cd uptake ratios of shoot/root for ryegrass were, on average, about 50‐fold and 27‐fold lower than that for cabbage and maize (Zea mays L.), respectively. These results showed that Cd could be easily transported into shoots of cabbage and maize, but was mainly confined to roots of ryegrass. We suggest that influx and transport rates, especially transport rate, could be used as plant physiological parameters for screening Cd‐excluding genotypes among monocotyledonous plants.     

Distribution,persistence, and fate of mexacarbate in the aquatic environment of a mixed‐wood boreal forest

Abstract

The distribution and persistence of aerially applied mexacarbate were studied in a New Brunswick aquatic forest environment after spraying twice at a dosage of 70 g A.l./ha using a fixed‐wing aircraft. Average droplet density (drops/cm²) and ground deposition (g A.1./ha) between the two applications differed considerably. The values for the first and second applications were 1.7 and 0.73, and 5.2 and 2.0, respectively; but the average NMD (20 μm) and VMD (36 μm) for both applications were nearly the same. The maximum 1‐h postspray concentrations of mexacarbate in the stream and pond waters were 0.73 and 18.74 ppb, respectively. Concentrations fell rapidly to below detection limits within 12 h in stream and within 3 d in pond water. Cattails (Typha latifolia), manna grass (Glyceria borealis) and bog moss (Sphagnum sp.) collected from the pond contained peak 1‐h postspray concentrations of 720, 482 and 81 ppb, respectively. The concentration levels decreased rapidly and the average half‐lives of the chemical in them were about 3.9, 8.5 and 2.0 h. Bog moss, stream moss (Fontinalis sp.), watercress (Nasturtium officinalis), buttercup (Ranunculus aquatilis) and green alga (Drapamaldia sp.) sampled from the stream sites did not contain measurable levels of mexacarbate. Also, caged and wild tadpoles (Rana clamitans melanota) from the pond, and brook trout (Salvelinus fontinalis) (caged and wild), Atlantic salmon (Salmo salar) (wild) and mayfly nymphs (Ephemeralla sp.) collected from the stream did not contain any of the material. Mexacarbate was not detected in stream and pond sediments. The demethylated products, 4‐methylamino and 4‐amino‐3,5‐xylyl methylcarbamates and the phenol, 4‐dimethylamino‐3,5‐xylenol, were frequently detected as metabolites in water and in the aquatic plants. The presence of these compounds showed that demethylation and hydrolytic routes are the major metabolic pathways for the dissipation of mexacarbate from these substrates.     

Genotypic Differences in Effects of Cadmium Exposure on Plant Growth and Contents of Cadmium and Elements in 14 Cultivars of Bai Cai

Abstract

Fourteen cultivars of bai cai (Brassica campestris L. ssp. chinensis var. communis) were grown in the nutrient solutions containing 0–0.5 μg mL^?1 of cadmium (Cd) to investigate genotypic differences in the effects of Cd exposure on the plant growth and uptake and distribution of Cd in bai cai plants. The Cd exposure significantly reduced the dry and fresh weights of roots and shoots, the dry weight ratio of shoot/root (S/R), total biomass, and chlorophyll content (SPAD value). Cd concentrations in bai cai ranged from 13.3 to 74.9 μg g^?1 DW in shoots and from 163.1 to 574.7 μg g^?1 DW in roots under Cd exposure, respectively. The considerable genotypic differences of Cd concentrations and accumulations in both shoots and roots were observed among 14 bai cai cultivars. Moreover, Cd mainly accumulated in the roots. Cd also caused the changes of uptake and distribution of nutrients in bai cai and under the influence of cadmium, the concentration of potassium (K) decreased in shoot and increased in root. However, the concentrations of magnesium (Mg), phosphorus (P), manganese (Mn), boron (B), and iron (Fe) increased in shoots and decreased in roots. In addition, Cd exposure resulted in an increase in calcium (Ca), sulphur (S), and zinc (Zn) concentrations in both shoots and roots but had no significant effects on the whole uptake of the examined mineral nutrients except for S.     

Ammonium,Nitrate and Nitrite Nitrogen and Nitrate Reductase Enzyme Activity in Groundnut (Arachis hypogaea L.) Fields After Diazinon,Imidacloprid and Lindane Treatments

Impacts of diazinon (O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate), imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] and lindane (1,2,3,4,5.6-hexachlorocyclohexane) treatments on ammonium, nitrate, and nitrite nitrogen and nitrate reductase enzyme activities were determined in groundnut (Arachis hypogaea L.) field for three consecutive years (1997 to 1999). Diazinon was applied for both seed- and soil-treatments but imidacloprid and lindane were used for seed treatments only at recommended rates. Diazinon residues persisted for 60 days in both the cases. Average half-lives (t_1/2) of diazinon were found 29.3 and 34.8 days respectively in seed and soil treatments. In diazinon seed treatment, NH₄ ⁺, NO₃ ^?, and NO₂ ^? nitrogen and nitrate reductase activity were not affected. Whereas, diazinon soil treatment indicated significant increase in NH₄ ⁺-N in a 1-day sample, which continued until 90 days. Some declines in NO₃ ^?N were found from 15 to 60 days. Along with this decline, significant increases in NO₂ ^?N and nitrate reductase activity were found between 1 and 30 days. Imidacloprid and lindane persisted for 90 and 120 days with average half-lives (t_1/2) of 40.9 and 53.3 days, respectively. Within 90 days, imidacloprid residues lost by 73.17% to 82.49% while such losses for lindane residues were found 78.19% to 79.86 % within 120 days. In imidacloprid seed-treated field, stimulation of NO₃ ^?N and the decline in NH₄ ⁺NO₂ ^?-N and nitrate reductase enzyme activity were observed between 15 to 90 days. However, lindane seed treatment indicated significant increases in NH₄ ⁺-N, NO₂ ^?-N and nitrate reductase activity and some adverse effects on NO₃ ^?N between 15 and 90 days.     

The effect of calcium and pH on nickel accumulation in and rhizotoxicity to pea (Pisum sativum L.) root-empirical relationships and modeling

The accumulation and rhizotoxicity of Ni to pea were investigated. Calcium, H, and Ni competed for root-binding sites with high pH and low Ca favoring more Ni accumulation. At low pH, Ca accumulation is the key factor determining root growth, while at medium to high pH, root elongation is more sensitive to Ni concentration. The tissue concentration of Ni and Ca ([Ni]t or [Ca]t, μmol g⁻¹ dry root) can be predicted from total dissolved Ni ([Ni]_T, μM), pH, and total dissolved Ca ([Ca]_T, mM) by two approaches. Approach 1 is the empirical equations [Ni]t = (0.361 pH-0.695[Ca]_T)*[Ni]_T and [Ca]t = 8.29 pH + 10.8 [Ca]_T. The second approach involves a two-step model. The surface-bound Ni and Ca are estimated from a surface adsorption model with binding constants derived from independent ion adsorption experiments. Then transfer functions are used to predict internal root Ni and Ca accumulation.