| synthesis and herbicidal activity of [3r,5s,6s]-3-benzyloxy-5- methoxy-1,7-dioxaspiro[5.5]undecane and [3r,5s,6s]-3-methoxy-5-benzyloxy-1,7-dioxaspiro[5.5]undecane. | the synthesis of spiroacetals [3r,5s,6s]-3-benzyloxy-5-methoxy-1,7-dioaxaspiro[5.5]undecane 3 and [3r,5s,6s]-3-methoxy-5-benzyloxy-1,7-dioaxaspiro[5.5]undecane4, where the substituents on the spiroacetal assembly are in a 1,3-diaxial orientation, is described. epoxidation of unsaturated spiroacetal 5 using dimethyldioxirane showed greater preference for the alpha-epoxide 11 over the beta-epoxide 12. treatment of the alpha-epoxide 11 with lithium diethylamide in tetrahydrofuran afforded both the ... | 1998 | 11672035 |
| biochemical characterization of a trypanosomatid isolated from the plant amaranthus retroflexus. | a protozoan flagelate has recently been isolated from amaranthus retroflexus. this plant grows near economically important crops in southeastern spain, which are known to be parasitized by phytomonas spp. the present study focuses on the characterization of the energy metabolism of this new isolate. these flagellates utilize glucose efficiently as their primary energy source, although they are unable to completely degrade it. they excrete ethanol, acetate, glycine, and succinate in lower amount, ... | 2003 | 10998214 |
| a study of pollen prevalence in relation to pollen allergy in malaysian asthmatics. | in this paper we report results of skin prick tests (spt) using pollen extracts on 200 patients with clinical symptoms of asthma, and results of a parallel study in which pollen was collected and classified over a period of 18 months. the patients were outpatients from the university hospital in kuala lumpur, malaysia, while the pollen grains were collected with a spore trap placed in the campus of the university of malaya, approximately one kilometer from the university hospital. pollen extract ... | 1998 | 9681122 |
| trypanosomatid protozoa in plants of southeastern spain: characterization by analysis of isoenzymes, kinetoplast dna, and metabolic behavior. | three flagellates of the family trypanosomatidae were isolated from mango fruits (mangifera indica) and from the stems of clover (trifolium glomeratum) and amaranth (amaranthus retroflexus) in southeastern spain and were adapted to in vitro culture in monophase media. the parasites showed an ultrastructural pattern similar to that of other species of the genus phytomonas. mango and clover isolates differed from amaranth isolates in ultrastructural terms. the isolates were characterized by isoenz ... | 1998 | 9610631 |
| characterization of chenopodiales (amaranthus retroflexus, chenopodium album, kochia scoparia, salsola pestifer) pollen allergens. | pollen extracts of the four taxonomically related weeds, amaranthus retroflexus (ama r), chenopodium album (che a), kochia scoparia (koc s), and salsola pestifer (s. kali) (sal p), were characterized by various methods including crossed immunoelectrophoresis (cie), crossed radioimmunoelectrophoresis (crie), and sds-page immunoblotting. the allergen profiles were determined by crie and sds-page ige immunoblotting. crie detected from one to four important allergens, while sds showed up to four ban ... | 1995 | 7573842 |
| regulation of ribulose-1,5-bisphosphate carboxylase/oxygenase activity in response to reduced light intensity in c4 plants. | the light-dependent regulation of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activity was studied in 16 species of c4 plants representing all three biochemical subtypes and a variety of taxonomic groups. rubisco regulation was assessed by measuring (a) the ratio of initial to total rubisco activity, which reflects primarily the carbamylation state of the enzyme, and (b) total rubisco activity per mol of rubisco catalytic sites, which declines when 2-carboxyarabinitol 1-phosphate ( ... | 1993 | 12231795 |
| application of weed seedbank ecology to low-input crop management. | pesticide use in the united states is concentrated in the corn belt, mainly in the form of herbicides on corn (zea mays) and soybean (glycine max). if this chemical load to the environment is to be reduced, without appreciably affecting crop yields, an intimate understanding of weed ecology is necessary. for annual weeds in the u.s. corn belt, critical ecological information includes seedbank density, seed dormancy, seedling emergence, and environmental variables that regulate these factors. for ... | 1993 | 27759235 |
| a comparison of dark respiration between c(3) and c(4) plants. | lower respiratory costs were hypothesized as providing an additional benefit in c(4) plants compared to c(3) plants due to less investment in proteins in c(4) leaves. therefore, photosynthesis and dark respiration of mature leaves were compared between a number of c(4) and c(3) species. although photosynthetic rates were generally greater in c(4) when compared to c(3) species, no differences were found in dark respiration rates of individual leaves at either the beginning or after 16 h of the da ... | 1992 | 16652945 |
| stable oxygen and hydrogen isotope composition of leaf water in c3 and c4 plant species under field conditions. | in this paper we make comparisons between the observed oxygen and hydrogen stable isotope composition of leaf water and the predictions of the craig-gordon model of evaporative isotopic enrichment. comparisons were made among two c3 species (chenopodium album and helianthus annuus) and two c4 species (amaranthus retroflexus and kochia scoparia), when plants were exposed to natural environmental conditions in the field. there were significant differences among the species for the hydrogen and oxy ... | 1991 | 28313802 |
| modification of the fluorescent allergosorbent test as an inhibition assay for determination of cross-reactivity among aeroallergens. | the fluorescent allergosorbent test was adapted as an inhibition assay to determine cross-reactivity between aeroallergens. with this method, similar antigenic determinants were found between short ragweed and giant ragweed, cocklebur, lamb's-quarter, rough pigweed, marsh elder, and goldenrod. cocklebur and giant ragweed were highly potent in their ability to competitively bind to short ragweed ige. the other pollens demonstrated lower potency of cross-reacting antigens. the fluorescent allergos ... | 1991 | 1704024 |
| role of ethylene metabolism in amaranthus retroflexus. | (14)c-ethylene was metabolized by etiolated pigweed seedlings (amaranthus retroflexus l.) in the manner similar to that observed in other plants. the hormone was oxidized to (14)co(2) and incorporated into (14)c-tissue components. selected cyclic olefins with differing abilities to block ethylene action were used to determine if ethylene metabolism in pigweed is necessary for ethylene action. 2,5-norbornadiene and 1,3-cyclohexadiene were effective inhibitors of ethylene action at 800 and 6400 mi ... | 1989 | 16666717 |
| the nitrogen use efficiency of c(3) and c(4) plants : iii. leaf nitrogen effects on the activity of carboxylating enzymes in chenopodium album (l.) and amaranthus retroflexus (l.). | the relationships between leaf nitrogen content per unit area (n(a)) and (a) the initial slope of the photosynthetic co(2) response curve, (b) activity and amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) and phosphoenolpyruvate carboxylase (pepc), and (c) chlorophyll content were studied in the ecologically similar weeds chenopodium album (c(3)) and amaranthus retroflexus (c(4)). in both species, all parameters were linearly dependent upon leaf n(a). the dependence of the ini ... | 1987 | 16665701 |
| the nitrogen use efficiency of c(3) and c(4) plants: ii. leaf nitrogen effects on the gas exchange characteristics of chenopodium album (l.) and amaranthus retroflexus (l.). | the effect of leaf nitrogen (n) on the photosynthetic capacity and the light and temperature response of photosynthesis was studied in the ecologically similar annuals chenopodium album (c(3)) and amaranthus retroflexus (c(4)). photosynthesis was linearly dependent on leaf n per unit area (n(a)) in both species. a. retroflexus exhibited a greater dependence of photosynthesis on n(a) than c. album and at any given n(a), it had a greater light saturated photosynthesis rate than c. album. the diffe ... | 1987 | 16665551 |
| the nitrogen use efficiency of c(3) and c(4) plants: i. leaf nitrogen, growth, and biomass partitioning in chenopodium album (l.) and amaranthus retroflexus (l.). | the effect of applied nitrogen (n) on the growth, leaf expansion rate, biomass partitioning and leaf n levels of chenopodium album (c(3)) and amaranthus retroflexus (c(4)) were investigated. at a given applied n level, c. album had 50% greater leaf n per unit area (n(a)) than a. retroflexus. nitrate accumulated at lower n(a) in a. retroflexus than c. album. a. retroflexus was more productive than c. album at high n, but c. album was more productive at low n. at high applied n, nitrogen use effic ... | 1987 | 16665550 |
| biomass production and nitrate metabolism of atriplex hortensis l. (c3 plant) and amaranthus retroflexus l. (c4 plant) in cultures at different levels of nitrogen supply. | pure and mixed cultures of the dicotyledons atriplex hortensis l. (c3 plant) and amaranthus retroflexus l. (c4 plant) were maintained under open air conditions in standard soil at low and high nitrogen supply levels.a comparison of shoot dry weight and shoot length in the various series shows that the growth of the aboveground parts of both species was severely reduced under low n conditions. in both pure and mixed cultures the differences resulting from low n vs. high n conditions was less pron ... | 1987 | 28311555 |
| role of benzoxazinones in allelopathy by rye (secale cereale l.). | two phytotoxic compounds [2,4-dihydroxy-1,4(2h)-benzoxazin-3-one (diboa) and 2(3h)-benzoxazolinone (boa)] were previously isolated and identified in 35-day-old greenhouse-grown rye shoot tissue. both compounds were also detected by tlc in greenhouse-grown root and fieldgrown shoot tissue. the concentration of diboa varied in the tissues, with the greatest quantity detected in greenhouse-grown shoots. diboa and boa were compared with β-phenyllactic acid (pla) and β-hydroxybutyric acid (hba) for a ... | 1987 | 24302054 |
| characteristics of chloroplast thylakoid lipid composition associated with resistance to triazine herbicides. | a detailed comparison of the polar-lipid composition of chloroplast thylakoid membranes isolated from triazine-susceptible and triazine-resistant biotypes of chenopodium album, senecio vulgaris, poa annua and amaranthus retroflexus has been carried out. no major differences in the composition of the bulk lipid matrix were found except for a slightly higher monogalactosyldiacylglycerol to digalactosyldiacylglycerol ratio in resistant compared with susceptible biotypes. there was, however, in the ... | 1985 | 24241445 |
| effects of root applications of gibberellic acid on photosynthesis and growth in c3 and c 4 plants. | the effects of root applications of gibberellic acid (ga3) on growth and photosynthesis of 12 species of plants including c3 monocots (triticum aestivum l., wheat, hordeum vulgare l., barley and avena sativa l., oat), c3 dicots (vigna radiata l., mung bean, cucurbita moschata l., squash and capsicum annuum l., pepper), c4 monocots (zea mays l., corn, sorghum vulgare l., sorghum and panicum ramosum l., millet) and c4 dicots (amaranthus retroflexus l., pigweed, kochia scoparis l., kochia and gomph ... | 1985 | 24442874 |
| the response of plants to elevated co2 : i. competition among an assemblage of annuals at two levels of soil moisture. | four coexisting annual plant species were grown in competition at three levels of co2 (300, 600, and 1,200 ppm) and two levels of soil moisture (moist and dry). plant height was higher at high co2 concentrations for the three c3 species but not for the c4 species (amaranthus retroflexus). total community biomass increased with increasing co2 at both soil moisture levels. the contribution of each species to total community biomass was influenced by co2 concentration. the effects were especially p ... | 1984 | 28310713 |
| growth analysis of corn and soybean response to allelopathic effects of weed residues at various temperatures and photosynthetic photon flux densities. | the effects of redroot pigweed (amaranthus retroflexus l.) and yellow foxtail [setariaglauca (l.) beauv.] residues on corn (zea mays l.) and soybeans [glycine max (l.) merr.] were evaluated at various temperatures and photosynthetic photon flux densities (ppfd) in a biotron. mathematical growth analysis techniques were used for the evaluation. redroot pigweed markedly reduced leaf area duration (lad), leaf weight ratio (lwr), and total dry matter production in both crops. yellow foxtail residue ... | 1983 | 24407817 |
| studies on the leaf of amaranthus retroflexus (amaranthaceae): ultrastructure, plasmodesmatal frequency, and solute concentration in relation to phloem loading. | both the mesophyll and bundle-sheath cells associated with the minor veins in the leaf of amaranthus retroflexus l. contain abundant tubular endoplasmic reticulum, which is continuous between the two cell types via numerous plasmodesmata in their common walls. in bundle-sheath cells, the tubular endoplasmic reticulum forms an extensive network that permeates the cytoplasm, and is closely associated, if not continuous, with the delimiting membranes of the chloroplasts, mitochondria, and microbodi ... | 1982 | 24271968 |
| the diurnal course of leaf gas exchange of the c4 species amaranthus retroflexus under field conditions in a 'cool' climate: comparison with the c3 species glycine max and chenopodium album. | the gas exchange of leaves of amaranthus retroflexus (c4) measured under fluctuating environmental conditions in an experimental garden in würzburg was compared with that of glycine max and chenopodium album (c3). consistent with previous observations, amaranthus had higher leaf diffusion resistance than the c3 species and low internal air space carbon dioxide concentration. due to high photosynthetic capacity, amaranthus fixed as much carbon during the light as the c3 species, even at low tempe ... | 1982 | 28311733 |
| determination of nad malic enzyme in leaves of c(4) plants : effects of malate dehydrogenase and other factors. | malate dehydrogenase may interfere with the assay of nad malic enzyme, as nadh is formed during the conversion of malate to oxaloacetate. during the present study, two additional effects of malate dehydrogenase were investigated; they are evident only if the malate dehydrogenase reaction is allowed to reach equilibrium prior to initiating the malic enzyme reaction. one of these (outlaw, manchester 1980 plant physiol 65: 1136-1138) might cause an underestimation of nad reduction by malic enzyme d ... | 1982 | 16662234 |
| lipid composition of chloroplast membranes from weed biotypes differentially sensitive to triazine herbicides. | chloroplasts were isolated from triazine-sensitive and triazine-resistant biotypes of common groundsel (senecio vulgaris l.), common lambsquarter (chenopodium album l.), and redroot pigweed (amaranthus retroflexus l.). chloroplast lipids were extracted and analyzed for differences among sensitive and resistant biotypes. the distribution of lipid between major lipid classes differed in chloroplasts from resistant and susceptible biotypes. chloroplasts from resistant biotypes contained higher prop ... | 1981 | 16661961 |
| biomass production of c3- and c4-plant species in pure and mixed culture with different water supply. | pure and mixed cultures of the dicotyledons atriplex hortensis l. (c3 plant) and amaranthus retroflexus l (c4) on the one hand and of the grasses avena sativa l (c3) and panicum miliaceum l. (c4) on the other hand were maintained in a standard soil with different ground water tables. after 12 weeks the length, dry weight and nitrogen-content of the aboveground and belowground parts of the plants, and in addition the carbon-and ash-content and the δ(13)c value of the aboveground parts were determ ... | 1981 | 28310064 |
| phase-sequence of redroot pigweed seed germination responses to ethylene and other stimuli. | phase-sequence studies showed that light, ethylene, and high temperature each enhanced germination of redroot pigweed (amaranthus retroflexus l.) seeds when given during the first 24 hours of seed imbibition. responses were maximal during the first 12 hours. after 48 hours all three stimuli given together caused 75% germination but each alone was ineffective. the main influence of water potential on seed germination occurred at about 24 hours, but the influence of co(2) extended into the second ... | 1981 | 16661865 |
| effects of temperature, water potential, and light on germination responses of redroot pigweed seeds to ethylene. | the responses of redroot pigweed (amaranthus retroflexus l.) seeds to nine ethylene concentrations between 0.5 and 50 microliters per liter were assessed at different temperatures and water potentials and in either continuous white light or darkness. under all experimental treatments, the probit-transformed percentages increased linearly with the log of the ethylene concentration. in dormant seeds, the slope of the response line was unaffected by either light or water potential but increased wit ... | 1980 | 16661350 |
| effects of diversity and pattern on relative yields of four michigan first year fallow field plant species. | 1. a study was designed to investigate the effects of intra and inter-specific competition on the productivity of single and multi-species stands of plants normally dominant in first year old-field communities of mid-michigan. the four species used were amaranthus retroflexus, chenopodium album, panicum capillare and setaria viridis. 2. specifically, we tested (1) the relationship between diversity and productivity, (2) the effect of arrangement (pattern) of individuals within an array of old-fi ... | 1980 | 28309565 |
| chloroplast membrane alterations in triazine-resistant amaranthus retroflexus biotypes. | the effectiveness of diuron, atrazine, procyazine, and cyanazine were compared in controlling growth of redroot pigweed (amaranthus retroflexus l.) in hydroponic culture. a very marked differential inhibition response was observed for atrazine between resistant and susceptible biotypes. procyazine and cyanazine exhibited less dramatic differential responses, whereas diuron was equally effective in controlling growth in both biotypes. photosystem ii activity of chloroplasts from both triazine-res ... | 1979 | 16592608 |
| further studies on oxalic acid biosynthesis in oxalate-accumulating plants. | l-ascorbic acid functions as a precursor of oxalic acid in several oxalate-accumulating plants. the present study extends this observation to include rumex crispus l. (curly dock), amaranthus retroflexus l. (red root pigweed), chenopodium album l. (lamb's-quarters), beta vulgaris l. (sugar beet), halogeton glomeratus m. bieb. (halogeton), and rheum rhabarbarum l. (rhubarb). several species with low oxalate content are also examined.when l-[1-(14)c]ascorbic acid is supplied to young seedlings of ... | 1978 | 16660342 |
| insect response to mixture and monoculture patches of michigan old-field annual herbs. | 1. the response of insects to the presence of discrete arrays of mixture and monoculture plots of weed species normally dominant in first-year michigan old-fields was studied. 2. plant species used were amaranthus retroflexus, chenopodium album, panicum capillare and setaria viridis. 3. two experiments were implemented, one with pure stands of each species and the other with mixture stands of equiproportionate numbers of each plant species (fig. 1). 4. sucking insects had significantly higher we ... | 1978 | 28309738 |
| dependence of phytochrome action in seeds on membrane organization. | germination of amaranthus retroflexus l. seeds imbibed at 40 c is enhanced by establishing the active form of phytochrome before a reduction in temperature to <32 c. the half-time for effectiveness of the lower temperature is about 8 min at 15 c. isolated membrane fragments of a. retroflexus seeds associated with the fluorescent probe 1,8-anilino-naphthalene sulfonate (ans) increase in structural order as the temperature is lowered through the 32 c region. the germination response is decreased b ... | 1978 | 16660228 |
| role of temperature in the germination ecology of three summer annual weeds. | ambrosia artemisiifolia l., chenopodium album l., and amaranthus retroflexus l. are three summer annual weeds that occur in disturbed habitats. in nature, the peak germination season for a. artemisiifolia and c. album is in early to mid-spring, while in a. retroflexus the peak germination season is late spring to early summer. furthermore, seeds of a. artemisiifolia germinate only in spring, while seeds of c. album and a. retroflexus germinate throughout the summer. in an attempt to explain the ... | 1977 | 28309185 |
| the facultative photoperiodic response in the reproductive development of amaranthus retroflexus l.: changes in the dose response during ontogeny. | the first inductive (short-day; sd) cycle advanced the initiation of reproductive development, while additional sd cycles progressively reduced the lag phase between the start of induction and initiation. the sensitivity to sd increased during ontogeny in long-days (ld) until even the requirement for the first sd cycle disappeared at the onset of "autonomous" flowering. in photo-induced plants, the postinitiation rate of elongation of the apex was accelerated as the sd dose was increased, but wa ... | 1977 | 24420629 |
| a kinetic analysis of the facultative photoperiodic response in amaranthus retroflexus l. | the ontogenetic change taking place in the facultative photoperiodic response of a. retroflexus to inductive short-day (sd) conditions was studied by exposing plants to continuous induction after different initial exposures to long-days (ld), and comparing the kinetics of their developmental responses (cumulative number of plants with reproductive apices, flowering stage, and height of the apical dome). as the plants progressed from emergence to "autonomous" flowering (i.e., in non-inductive con ... | 1977 | 24420220 |
| [phytotoxicity of hydrazones of aromatic aldehydes]. | a series of hydrazones of aromatic aldehydes (b) was prepared and tested for phytotoxicity. these compounds are bioisosters of 1-aryltriazenes (a) which were found to possess interesting phytotoxic properties in a previous research. the substances studied (tables i leads to iii: compounds(i leads to clxxx)) some of which were previously unrecorded, were prepared by the usual procedures from the required aldehyde and hydrazine derivative. the phytotoxicity of all the compounds was studied using s ... | 1976 | 1269737 |
| rehydration of phytochrome in imbibing seeds of amaranthus retroflexus l. | | 1972 | 16658024 |
| changes in phytochrome expressed by germination of amaranthus retroflexus l. seeds. | effects of red (600 to 680 nanometers) and far red (700 to 760 nanometers) irradiances on amaranthus retroflexus l. seeds indicate that synthesis of phytochrome in the red-absorbing form takes place in water-imbibed nongerminating seeds at 35 c. after 96 hours in darkness, conversion of about 0.10% phytochrome to the far red-absorbing form induces 50% germination. continuous far red radiation at 35 c with an irradiance of 0.4 x 10(-10) einsteins per square centimeter per second caused photoinact ... | 1971 | 16657672 |
| action of phytochrome during prechilling of amaranthus retroflexus l. seeds. | dark germination of amaranthus retroflexus l. seeds at 35 degrees increased after several days of prechilling at 20 degrees or lower. irradiation with far-red light for short periods during the early hours of a prechilling period at 10 degrees inhibited subsequent dark germination at 35 degrees . the inhibition was completely reversible with red light. far-red irradiation in the latter part of the prechilling period was less effective. increased dark germination of a. retroflexus seeds following ... | 1969 | 16657136 |
| effect of kinetin on formation of red pigment in seedlings of amaranthus retroflexus. | kinetin induces formation of red pigment in seedlings of amaranthus retroflexus in the dark. this effect is similar to the light-induced formation of pigment. light and kinetin do not act in a simple additive way. the pigment is not an anthocyanin, and its formation is not affected by inhibitors of anthocyanin formation. | 1960 | 17745680 |