bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors of Wild Oat (Avena fatua) Interference on Spring Barley (Hordeum vulgare) Growth and Yield
Authors: Morishita Don W. , Thill Donald C.
Published: May 2019

Field experiments were conducted in 1983 and 1984 to measure the interference of wild oat (Avena fatuaL. # AVEFA) removed at various stages of development (two to three leaves, two to three tillers, two nodes, and heading), plus treatments with wild oat not removed, and wild oat-free stands on the growth and yield of spring barley (Hordeum vulgareL. ‘Advance’). The final plant density of barley and wild oat was 160 and 170 plants/m2, respectively. Based on aboveground barley biomass and yield, the critical duration of wild oat interference began about the two-node stage and continued until maturity of the barley. Wild oat interference reduced barley biomass, the number of tiller heads/plant, tiller heads/unit area, and tiller grain yield, but not the number or grain yield of the main-stem heads. Wild oat did not affect the soil matric potential or the barley total plant and soil nitrogen contents. However, wild oat did reduce total water and turgor potential in barley at the boot stage of growth, which may have affected tiller head formation.
Temperature Factors Limiting the Spread of Cogongrass (Imperata cylindrica) and Torpedograss (Panicum repens)
Authors: Wilcut John W. , Truelove Bryan , Davis Donald E. , Williams John C.
Published: May 2019

Greenhouse, growth chamber, and field studies were conducted to determine effects of temperature on the potential of cogongrass (Imperata cylindricaL. Beauv. # IMPCY) and torpedograss (Panicum repensL. # PANRE) to spread beyond present distribution in the Lower Coastal Plains of Southeastern United States. Johnsongrass [Sorghum halepense(L.) Pers. # SORHA] was included in the study for comparative purposes. Growth of each species was greater with day/night temperature regimes of 30/25 C than with 27/22 or 24/18 C. Apical six-node-long rhizome fragments of all three species were killed by a 24-h exposure to −4.5 C. Johnsongrass produced at least three to five times more dry matter than either cogongrass or torpedograss. Order of interspecific competitiveness under 30/25, 27/22, and 24/18 C day/night temperature regimes was johnsongrass > torpedograss > cogongrass. After 2 yr, johnsongrass and torpedograss competition reduced common bermudagrass [Cyndon dactylon(L.) Pers. # CYNDA] yield by 99 and 37%, respectively, while cogongrass competition did not affect common bermudagrass yield. It is concluded that cogongrass and torpedograss are unlikely to spread into more temperate regions of the United States. However, both species are apt to become even more widespread and troublesome in the Lower Coastal Plains of Southeastern United States.
The Morphological and Physiological Response of Slender Oat (Avena barbata) to the Herbicides Barban and Difenzoquat
Authors: Price Steven C. , Hill James E. , Allard Robert W.
Published: May 2019

The morphological and physiological response of the slender oat (Avena barbataPott ex Link # AVEBA) to the herbicides barban (4-chloro-2-butynyl 3-chlorophenylcarbamate) and difenzoquat (1,2-dimethyl-3,5-diphenyl-1H-pyrazolium) in conjunction with decreased water availability was determined for seven populations, representing three ecotypes, under greenhouse conditions. Generally, within the range of sublethal herbicide doses, with increasing herbicide rates, phytotoxicity ratings increased, but plant dry weight, tiller height, and number of spikelets were decreased. Also, the number of juvenile tillers decreased, while that of fertile tillers increased. Flag leaf area increased and flowering was delayed. The ratio of number of spikelets to plant dry weight and seed weight was influenced the least. Under the highest rates of difenzoquat, the within-plant variance of spikelet number decreased, indicating that there may have been a more equal partitioning of resources amongst tillers for spikelet production. The general influence of water stress was to amplify the effect of the herbicide. For example, the dry treatment reduced dry weight and tiller height, and delayed flowering. Within a particular herbicide treatment, the effect of the water stress was to cause reduced within-plant variance for days to flowering, flag leaf area, and number of spikelets. Three reactions were observed that could have helped buffer decreases in spikelet production: 1) An increased fraction of the dry weight of the plants was partitioned into the spikelets at the expense of other vegetative matter, 2) the increased leaf area of the primary tiller may have helped counterbalance any reduction in photosynthesis caused by herbicide action, and 3) an increased number of juvenile tillers was converted into fertile tillers resulting in an increased number of mature tillers. These data indicate that the slender oat has a remarkable “phenotypic plasticity,” which enables it to maintain reproductive structures under sublethal herbicide doses.
Glyphosate Uptake by Suspension-Cultured Potato (Solanum tuberosumandS. brevidens) Cells
Authors: Burton James D. , Balke Nelson E.
Published: May 2019

Characteristics of glyphosate [N-(phosphonomethyl)glycine] uptake for as long as 3 days by plant cells were studied using suspension-cultured potato (Solanum tuberosumL. cv. ‘Red Pontiac’ andS. brevidensPhil.) cells. An experimental system was developed wherein uptake was assayed in a reduced salt medium that minimized cell growth yet maintained cell viability. Glyphosate uptake was nonlinear over time; an immediate rapid uptake phase was followed by uptake at a decreased rate that continued through 72 h. Glyphosate uptake was the same in both an experimental uptake medium (reduced salt and sucrose, no hormones) and in the complete growth medium used for routine cell growth. The pattern of glyphosate uptake was similar with both Red Pontiac andS. brevidenscells, though uptake was greater in Red Pontiac cells. Glyphosate uptake was not inhibited by 1 mM CaSO4, MgSO4, MnSO4, or ZnSO4. Rather, uptake was inhibited by the absence of salts at 8 h, and ZnSO4and MnSO4increased uptake. Similarly, increasing concentrations (0 to 5 mM) of CaSO4and CaCl2did not inhibit uptake, whereas the absence of either salt of Ca2+decreased uptake. Increasing concentrations of (NH4)2SO4(0 to 150 mM) did not affect glyphosate uptake, but (NH4)2SO4at 50 mM and above was toxic to the cells.
Using Protein Electrophoresis to Investigate the Phylogeny of Velvetleaf (Abutilon theophrasti)
Authors: Stegink Steven J. , Spencer Neal R.
Published: May 2019

Native Polyacrylamide gel electrophoresis (PAGE) and enzyme activity staining were used to identify possible progenitor species of velvetleaf (Abutilon theophrastiMedic. # ABUTH). Multiple forms of superoxide dismutase activity were observed in each of the plants surveyed. Three enzyme forms were common to all the species and bio types while one form was different in the velvetleaf biotypes compared to the other species. Multiple forms of peroxidase activity were also detected. The three velvetleaf biotypes possessed identical enzyme forms with minimal similarity to peroxidase forms found in the other species. Multiple forms of esterase activity separated as two nonoverlapping groups. A slowly migrating group was observed in all the velvetleaf biotypes and a more rapidly migrating group characterized the remainingAbutilonspecies. The results of this study indicated that the progenitors of velvetleaf were not among the species surveyed and suggested that the progenitors may no longer be extant.
Effects of Row Spacing, Benomyl, and Duration of Sicklepod (Cassia obtusifolia) Interference on Soybean (Glycine max) Yields
Authors: McWhorter Chester G. , Sciumbato Gabe L.
Published: May 2019

Field experiments were conducted during a 3-yr period to study the effects of three soybean[Glycine max(L.) Merr. ‘Hill’] row spacings, four periods of sicklepod (Cassia obtusifoliaL. # CASOB) competition, and timing of fungicide application for control of seed and foliar diseases of soybeans on soybean yields and growth of sicklepod Competition of sicklepod for 4 weeks reduced soybean yields in 2 of the 3 yr. Competition for the entire season significantly reduced the yield of soybeans regardless of row spacing. Average soybean yields were higher with 51-cm row spacings than with 102-cm row spacings regardless of fungicide treatment or period of sicklepod competition. Foliar applications of benomyl significantly increased soybean yields in only 1 of 3 yr. Sicklepod plants did not grow taller than soybeans until more than 96 days after emergence. Greatest rate of increase in weights of individual sicklepod plants and growth of axillary branches was in the period from 72 to 96 days after emergence. During this time, there was about an 8-fold increase in the number of leaves produced by sicklepod plants. The most rapid daily increase in height of sicklepod was in the period from 96 to 100 days after emergence when more than 50% of the total growth occurred. Height and weight of sicklepod plants were less when soybeans were grown in 25-cm row spacings than in 102-cm row spacings. No differences were noted in die internal microflora of soybean seed collected from fold plots with regard to the presence of sicklepod, duration of sicklepod interference, or timing of fungicide application.
Mode of Clopyralid Uptake by Honey Mesquite (Prosopis glandulosa)
Authors: Bovey Rodney W. , Hein Hugo , Meyer Robert E.
Published: May 2019

Leaves absorbed high amounts of clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) as foliar sprays on honey mesquite (Prosopis glandulosaTorr. # PRCJG) as indicated by concentrations of 10 μg/g fresh wt or more in basal stem phloem by 4 days after treatment. Small quantities of clopyralid (< 1 μg/g) were detected in basal stem phloem after spray applications of clopyralid to defoliated plants or roots treated by soil application. When applied to foliated plants, the 0.56 kg/ha of clopyralid killed 60% or more plants, but none were killed when clopyralid sprays were applied to defoliated plants or when 2.2 kg/ha of clopyralid was applied to the soil. Water, diesel oil plus water, or water plus surfactant were equally effective as clopyralid carriers as foliar sprays.
Potential Mechanisms for Bentazon Antagonism by Haloxyfop
Authors: Gerwick B. Clifford
Published: May 2019

The antagonism of the methyl ester of haloxyfop {2-[4-[[3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy propanoic acid} by bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one-2,2-dioxide] was evaluated through studies of absorption and translocation in yellow foxtail [Setaria lutescens(Weig. ex Stuntz.) Hubb. # SETLU]. Leaf penetration of haloxyfop was reduced 37% in the presence of bentazon. Bentazon had no effect on translocation from the treated leaf. Direct chemical interactions and contact activity by bentazon do not account for the reduced uptake of haloxyfop. Experimental evidence shows the benzothiadiazione structural class of chemistry to be general antagonists of absorption for foliarly applied herbicides.
Absorption, Translocation, and Toxicity of Foliar-Applied Imazaquin in Yellow and Purple Nutsedge (Cyperus esculentusandC. rotundus)
Authors: Nandihalli Ujjanagouda B. , Bendixen Leo E.
Published: May 2019

Imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} absorption, translocation, and toxicity were investigated in yellow nutsedge (Cyperus esculentusL. # CYPES) and purple nutsedge (C. rotundusL. # CYPRO) after foliar treatment. Imazaquin rates from 0.125 to 0.375 kg ai/ha were sprayed on nutsedge plants at the four-leaf stage. Compared to untreated plants, these rates reduced the main shoot growth of yellow nutsedge by 70 to 86% and that of purple nutsedge by 80 to 92% at 28 days after application (DAA). However, the regrowth as measured by tiller production was significantly greater at 0.125 and 0.188 kg/ha rates than at higher rates. The plants treated with 0.313 and 0.375 rates had no rhizomes or tubers at the 28 DAA sampling. In yellow nutsedge, absorption of14C-imazaquin increased from 36% at 1 DAA to 57% at 8 DAA. of the total absorbed14C, 12% translocated from the treated area by 8 DAA. Roots and rhizomes accumulated equal amounts of radioactivity. In purple nutsedge, the absorption of imazaquin increased from 17% at 1 DAA to 53% at 8 DAA. Translocation of absorbed14C in purple nutsedge at 8 DAA was 21%. Rhizomes accumulated significantly greater amounts of14C than the roots.
Use of Winter Wheat (Triticum aestivum) Cultivars and Herbicides in Aiding Weed Control in an Ecofallow Corn (Zea mays) Rotation
Authors: Ramsel Robert E. , Wicks Gail A.
Published: May 2019

An experiment involving six winter wheat (Triticum aestivumL.) cultivars, an early-April herbicide application on wheat and on four dates after wheat harvest, and the growth of a subsequently planted corn (Zea maysL.) crop was conducted at North Platte, NE. ‘Centurk 78’ suppressed barnyardgrass [Echinochloa crus-galli(L.) Beauv. # ECHCG] more than ‘Bennett’ and ‘Eagle’ in the growing wheat and after wheat harvest in July, but there were no differences in weed yield among cultivars in corn planted 11 months later. Herbicides applied to the tillering wheat in early April improved weed control in wheat and the subsequent corn crop. Also, herbicides were applied 5, 25, 45, and 300 days after wheat harvest. Weed growth increased and soil water decreased as spraying dates were delayed. Herbicides applied 5 days after harvest did not maintain adequate weed control in the corn planted 11 months after wheat harvest and low corn yield resulted. Plots receiving herbicides 300 days after wheat harvest had the least soil water in the fall after wheat harvest but the best weed control in corn and highest corn yields because of better weed control in corn.
Effect of Chemical Structure, Temperature, Crop Oil Concentrate, and Bentazon on the Behavior of Haloxyfop in Yellow Foxtail (Setaria glauca) – a Quantitative Modeling Approach
Authors: McCall Philip J.
Published: May 2019

A mathematical model describing the behavior of14C-haloxyfop {2-[4-[(3-chloro-5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} and its methyl and ethoxyethyl esters on yellow foxtail [Seteria glauca(L.) Beauv. #3SETLU] has been developed to evaluate volatility, penetration, ester transformation, metabolism, and transport of the chemical in the plant system. The effects of crop oil concentrate, temperature, structure of the molecule, and the addition of bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] to the application solution on the kinetic rate constants have been studied. Crop oil concentrate was found to dramatically increase penetration at an optimal level of approximately 0.3% (v/v). Significant increases in rate constants were observed at higher temperatures. Esters were rapidly converted to the acid in the plant with conversion of the ethoxyethyl ester being approximately twice as fast as the methyl ester. Subsequent metabolism of the acid proceeded at a moderate rate which was independent of the original ester form of the molecule. All kinetic processes were described by first-order rate constants with the exception of transport which appeared to slow a few hours after application even though acid levels in the plant were high. When bentazon was applied in combination with haloxyfop-methyl, penetration of the ester was somewhat inhibited, while transport of radioactivity associated with the molecule to other plant parts was dramatically reduced.
Effects of Napropamide on Growth and Anatomy of Corn,Zea mays, Roots
Authors: Di Tomaso Joseph M. , Ashton Floyd M. , Rost Thomas L.
Published: May 2019

Structural studies were conducted to evaluate the effects of napropamide on the growth and development of corn roots. At 1.0 and 10.0 μM napropamide, root growth was inhibited severely within 3 days of seed germination. Root diameter within 1 mm of the root apex doubled and numerous lateral root primordia were observed within 10 mm of the meristem tip in treated roots. The number of cortical parenchyma cell files, xylem vessel, and phloem sieve tube strands also significantly increased. Average cortical cell size did not change, regardless of the treatment. A lateral expansion of the meristematic region of the root coincided with a slight reduction in meristem length but resulted in an overall increase in meristem volume. However, enlargement of the meristem occurred despite a reduction in the number of mitotic figures in the root meristem. Treatment of excised root tips for 24 h with 20 μM napropamide reduced the number of mitotic figures 84%.
Effects of Phenology on Translocation Patterns of Several Herbicides in Quackgrass,Agropyron repens
Authors: Harker K. Neil , Dekker Jack
Published: May 2019

A growth room study was conducted to evaluate the effect that timing of application has on the distribution of several herbicides in quackgrass. Uniformly labeled14C-sucrose and the radiolabeled herbicides glyphosate, sethoxydim, the butyl ester of fluazifop, and the methyl ester of haloxyfop were applied to quackgrass (ranging from the three- to eight-leaf stage) propagated from six-bud rhizome segments. Five days after treatment the plants were harvested, lyophilized, and later sectioned, mapped, and oxidized in preparation for14C quantification. In most cases, slightly more14C was translocated to the shoots than to the rhizomes.14C translocation to the rhizomes was similar at all growth stages. The14C accumulating in the rhizomes exhibited a nonuniform distribution pattern with more14C in the distal areas of new rhizomes than in the other areas of the rhizome system. Plants treated with haloxyfop had a more uniform distribution of14C along their rhizomes than did those treated with fluazifop or sethoxydim.
The Potential of an Endemic Fungus,Colletotrichum gloeosporioides, for Biological Control of Round-Leaved Mallow (Malva pusilla) and Velvetleaf (Abutilon theophrasti)
Authors: Mortensen Knud
Published: May 2019

A fungal pathogen,Colletotrichum gloeosporioides(Penz.) Sacc. f. sp.malvae, isolated from anthracnose symptoms of round-leaved mallow (Malva pusillaSm.), was shown in greenhouse tests to be host specific toMalvaspp. and velvetleaf (Abutilon theophrastiMedic. #3ABUTH), and only with slight attack on hollyhock [Althaea rosea(L.) Cav. # ALGRO],Malope trifidaCav., and Venice mallow (Hibiscus trionumL. # HIBTR). Round-leaved mallow plants inoculated with a spore suspension of the fungus were killed after 17 to 20 days. It was less pathogenic on velvetleaf with 60 to 70% attack. The fungus can readily be cultured and field tests from 1982 to 1987 resulted in excellent control of round-leaved mallow under natural conditions. Therefore, it has good potential for biological control of round-leaved mallow in field crops.
Distribution of Triazine-Resistant Smooth Pigweed (Amaranthus hybridus) and Common Lambsquarters (Chenopodium album) in Virginia
Authors: Vencill William K. , Foy Chester L.
Published: May 2019

The distribution pattern ofs-triazine-resistant biotypes of common lambsquarters (Chenopodium albumL. #3CHEAL) and smooth pigweed (Amaranthus hybridusL. # AMACH) in Virginia was determined. Seeds were collected from suspected triazine-resistant biotypes of both species. Triazine resistance was confirmed by measuring chlorophyll fluorescence in the presence of atrazine [6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine]. Greenhouse bioassay with whole-plant material and a sinking leaf disc assay were also performed as further confirmation of triazine resistance. Triazine-resistant smooth pigweed was confirmed in 19 counties and common lambsquarters in eight counties in Virginia. Triazine-resistant smooth pigweed and common lambsquarters were located mostly in the northern and southwestern highlands of the state where there has been a long history of triazine use in no-till corn (Zea maysL.) production.S-triazine-resistant biotypes were also cross-resistant to other representatives-triazine andas-triazine herbicides but susceptible to the substituted urea herbicide diuron [N′-(3,4-dichlorophenyl)-N,N-dimethylurea].
Uptake, Translocation, and Metabolism of Thiobencarb in Two Lettuce,Lactuca sativa, Cultivars
Authors: Reiners Stephen , Gorski Stanley F. , Victor Desouza J. J.
Published: May 2019

Two lettuce cultivars exhibiting differential levels of tolerance to thiobencarb in soil and nutrient solution assays were examined. Seedlings of ‘Dark Green Boston’ (BOS), a susceptible cultivar, were found to show significant inhibitions in foliar growth compared to the tolerant ‘Great Lakes 366’ (GLA). Reductions of 57% occurred in BOS leaf dry weights at rates of 3 μM thiobencarb as soon as 4 days after treatment. In addition, growth abnormalities including fused leaves were observed in the BOS cultivar, indicating inhibition early in leaf development at the meristem. Twenty-nine and 22% of applied14C-thiobencarb was absorbed from nutrient solution by BOS and GLA, respectively. This difference is probably due to BOS having a 50% greater root system at the time of treatment. Greater absorption and accumulation of radioactivity in the leaves, as well as significantly greater amounts of parent14C-thiobencarb in the foliage of BOS compared to GLA (30 and 19%, respectively) may account for the selectivity observed. Metabolism of14C-thiobencarb occurred within 1 day in both cultivars, with the apparent production of herbicide conjugates accounting for more than 90% of the extracted radiolabel 12 days after treatment. A thiobencarb sulfoxide metabolite was not identified in these studies, indicating sulfoxide production is not a mechanism of selectivity in lettuce.
Ray Achene Polymorphism and Germination in Ragweed Parthenium (Parthenium hysterophorus)
Authors: Dubey Sarbesh K. , Pandey Harendra N.
Published: May 2019

Ragweed parthenium (Parthenium hysterophorusL. #3PTNHY) growing at six localities between 28°46′N and 13°O'N latitudes in India produced polymorphic ray achenes that varied in size and weight. Frequency of small achenes (1.9 to 2.2 mm) was higher at lower latitude (13°O'N) and that of large achenes (2.5 to 2.8 mm) at higher latitude (28°46′N). Achene weight was positively correlated with its germination percentage. Large-heavy achenes showed better germination than small-light ones.
Characterization of Reciprocal Hybrids of Common Ragweed,Ambrosia artemisiifolia, and Giant Ragweed,A. trifida
Authors: Vincent Gilles , Lauzer Denis , Cappadocia Mario
Published: May 2019

Common ragweed (2n=36), giant ragweed (2n = 24), and their reciprocal F1hybrids (2n = 30) were analyzed for a number of traits. Hybrids of the type giant ragweed♀ × common ragweed♂ were obtained via immature embryo culture. The analyses revealed a surprising contribution of the pollen parent for features such as biomass, leaf area, and specific leaf area. Leaf morphology, however, was similar to the maternal parent. One plant, originating from crosses of the type common ragweed♀ × giant ragweed♂, developed abnormally and cytological analysis revealed the presence of 24 chromosomes in its somatic cells. Probably this plant had an androgenetic origin.
Factors Limiting the Distribution of Cogongrass,Imperata cylindrica, and Torpedograss,Panicum repens
Authors: Wilcut John W. , Dute Roland R. , Truelove Bryan , Davis Donald E.
Published: May 2019

Greenhouse, growth chamber, and laboratory studies were conducted to determine anatomical and morphological characteristics and cultural practices limiting the distribution of cogongrass, torpedograss, and johnsongrass in the United States. Cogongrass did not produce axillary buds along most of the rhizome nor regenerate when apical six-node-long rhizome segments were buried deeper than 8 cm. Both torpedograss and johnsongrass produced axillary buds along the entire lengths of their rhizomes. Torpedograss shoot emergence decreased at burial depths between 8 and 16 cm. Shoot emergence from johnsongrass rhizomes was not affected by burial as deep as 16 cm. Rhizomes of all three species were tolerant of desiccation. Cogongrass grew better in soil at pH 4.7 than in soil at pH 6.7, whereas torpedograss and johnsongrass grew equally well in either pH. It is postulated that cogongrass spread is limited by lack of axillary bud formation on most of the rhizome and the inability of rhizomes to send up new shoots if buried deeper than 8 cm. These factors could account for the intolerance of cogongrass to cultivation. Torpedograss appears to spread only vegetatively due to the lack of viable seed production.
Interspecific and Intraspecific Interference of Broadleaf Signalgrass (Brachiaria platyphylla) in Rice (Oryza sativa)
Authors: McGregor John T. , Smith Roy J. , Talbert Ronald E.
Published: May 2019

Field experiments were conducted in 1984 and 1985 at Stuttgart, AR, to investigate the interspecific and intraspecific interference of broadleaf signalgrass densities of 0, 10, 50, 100, and 150 plants/m2with rice. In 1984, significant reductions in rice leaf area index (LAI) occurred 6 weeks after emergence with all broadleaf signalgrass densities. The first reduction in LAI occurred 8 weeks after emergence at the density of 150 plants/m2in 1985. Densities of 50 plants/m2or greater reduced rice dry weight 6 weeks after emergence in 1984, and the highest density of 150 plants/m2reduced rice dry weight 12 weeks after emergence in 1985. Height of rice was reduced by densities of 100 and 150 plants/m2. Linear regression equations indicated that each broadleaf signalgrass plant/m2reduced rough rice yield 18 kg/ha both years. Growth of broadleaf signalgrass was reduced by interspecific and intraspecific interference. The dry weight of broadleaf signalgrass increased at a decreasing rate at plant densities of 100 to 150/m2when grown alone in 1984 and 1985, when a quadratic equation best described the response. Regression equations indicated interspecific interference from rice reduced broadleaf signalgrass dry weight an average of 48 and 81% in 1984 and 1985, respectively. The height of broadleaf signalgrass was greater when grown with rice than when grown alone.
Postemergence Herbicide Suppression of Wheat, Triticum aestivum, Growing with Alfalfa, Medicago sativa
Authors: Beardmore Richard A. , Linscott Dean L.
Published: May 2019

Two field experiments were conducted in 1984 and 1985 to determine the effects of fluazifop, haloxyfop, and sethoxydim on the suppression of water uptake and competition of wheat to seedling alfalfa. In all cases, suppression of wheat growth and stand led to significant reduction in soil water use. The amounts of conserved soil water significantly correlated with increased numbers of alfalfa plants; the correlation coefficients, respectively, for mid- and late-summer plantings were 0.47 and 0.41 in 1984 and 0.90 and 0.86 in 1985. Conservation of soil water was attributed to growth reduction or cessation of wheat growth by the herbicides and, to some extent, suppression of wheat leaf transpiration. All of the three herbicides would be effective in controlling volunteer wheat in a new alfalfa planting.
Cinmethylin for Weed Control in Soybeans,Glycine max
Authors: Bhowmik Prasanta C.
Published: May 2019

A 3-yr study was conducted to evaluate efficacy and soybean tolerance of cinmethylin. Cinmethylin was applied preemergence alone at 0.6, 0.8, and 1.0 kg ai/ha or in combination with metribuzin at 0.3 kg/ha. These treatments did not injure soybeans in field trials in 1984, 1985, and 1986. The combination of cinmethylin at 0.7 kg/ha and metribuzin at 0.3 kg/ha controlled more than 90% of large crabgrass, fall panicum, and yellow foxtail. Redroot pigweed and common lambsquarters control was also excellent. Residual control of all grass species was excellent for 8 weeks after preemergence application, followed by reduced control in two of the three grasses. The combination of cinmethylin and metribuzin at 0.7 and 0.3 kg/ha, respectively, significantly increased soybean yields compared to those of untreated plots. These yields were comparable with those obtained from the combination of alachlor and metribuzin at 2.0 and 0.3 kg/ha, respectively. Cinmethylin treatments had no adverse effects on soybean yield components including pods/plant, seed/pod, and seed weight. Cinmethylin shows potential as a preemergence herbicide for full-season weed control in soybean production.
Differential Metabolism of Metribuzin by Downy Brome (Bromus tectorum) and Winter Wheat (Triticum aestivum)
Authors: Devlin Daniel L. , Gealy David R. , Morrow Larry A.
Published: May 2019

At both 15 and 25 C, following a 24-h root absorption period, absorbed14C-metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] was metabolized approximately 30% more rapidly to water-soluble and terminal fiber metabolites by winter wheat (Triticum aestivumL.) than by downy brome (Bromus tectorumL. # BROTE). Both species metabolized a greater proportion of metribuzin in leaf sheaths and roots than in the leaf blades. This was attributed to the increased incorporation of metribuzin into fiber. After an initial leaf extraction, metribuzin and the metabolites deaminated metribuzin (DA), deaminated diketo metribuzin (DADK), and diketo metribuzin (DK) partitioned into a chloroform fraction and five unidentified water-soluble metabolites into an aqueous fraction. At both 15 and 25 C, downy brome absorbed approximately three times more metribuzin per fresh weight than did winter wheat. The mechanism of differential tolerance of downy brome and winter wheat to metribuzin was attributed to the ability of winter wheat to metabolize metribuzin more rapidly and absorb less metribuzin than downy brome.
Absorption, Translocation, and Metabolism of Foliage-Applied Chloramben in Velvetleaf (Abutilon theophrasti) and Soybean (Glycine max)
Authors: Ozair Chaudhry A. , Moshier Loren J. , Werner Georgina M.
Published: May 2019

A quantitative assay using14C-chloramben (3-amino-2,5-dichlorobenzoic acid) revealed that velvetleaf (Abutilon theophrastiMedic. # ABUTH) leaves absorbed a greater amount of chloramben formulated as an acid than as a sodium salt. A surfactant increased14C-chloramben absorption 5 days, but not 1 day, after application. Translocation of14C-label out of treated leaves was greater in velvetleaf than in soybean [Glycine max(L.) Merr.]. Differences in the amount of14C-label as unmetabolized chloramben in ethyl acetate extracts of treated leaves were not detected between velvetleaf and soybean. The amount of unmetabolized chloramben was greater in the shoot above the treated leaf in velvetleaf (58% of total label recovered) than in soybean (35% of recovered label). The amount of recovered14C-label in unextractable form was greater in treated leaves of soybean compared to velvetleaf.
Germination ofSorghum almumSeeds and Longevity in Soil
Authors: Eberlein Charlotte V.
Published: May 2019

Sorghum-almum (Sorghum almumParod. # SORAL) is a weakly perennial, rhizomatous grass that in northern climates reproduces mainly by seeds. Environmental factors influencing seed germination and the longevity of buried seeds were studied in growth chamber and field experiments. Alternating temperatures of 20 C for 16 h and 30 C for 8 h were optimum for germination. Light was not critical to germination. Germination varied only slightly across a pH range from 5.0 to 8.8 but decreased sharply below pH 5. Osmotic potentials greater than −0.9 MPa reduced germination substantially, and no germination occurred at −1.5 MPa. Limited germination occurred at NaCl concentrations of 340 mM, and no germination occurred at 510 mM. Seeds that were either mechanically scarified or afterripened for 6 months had a higher percent germination and germination rate than untreated seeds. Sorghum-almum seedling emergence was 11% from seeding depths of 20 cm, but emergence was 67% or higher from seeding depths of 15 cm or less. In field studies, viability of seeds placed on the soil surface or buried 3 or 8 cm was 2% or less at 12 months and 0% at 18 months after burial. Viability of seeds buried 15 and 23 cm was 0.3 and 26%, respectively, at 24 months after burial. Thus, tillage that buried sorghum-almum seeds 20 cm or more could reduce emergence but would also prolong seed persistence. Shallow tillage should favor depletion of sorghum-almum seed reserves.
Breakage of Seed Dormancy of Field Pennycress (Thlaspi arvense) by Growth Regulators, Nitrate, and Environmental Factors
Authors: Saini Hargurdeep S. , Bassi Pawan K. , Goudey J. Stephen , Spencer Mary S.
Published: May 2019

Effects of ethylene, gibberellins, kinetin, nitrate, light, and temperature, each alone or combined with other factors, were studied on the germination of dormant seed of field pennycress (Thlaspi arvenseL. # THLAR). Treated seed were incubated at a range of constant temperatures, at temperatures alternating daily between 12 and 22 C (12 h each), or at 12 C followed by transfer to 22 C. No germination ocurrred in water under any conditions. When applied in the dark KNO3had no effect on germination under any of the temperature regimes. A combination of KNO3, light, and a shift in temperature from 12 to 22 C induced 100% germination. Four days of incubation at 12 C induced maximal seed sensitivity towards KNO3+ light, and the sensitivity remained unchanged if the incubation at 12 C was extended to 15 days. Upon transfer to 22 C, the effect of low-temperature incubation was lost within 3 days. Of the two seed lots studied, one had a relatively lower chilling requirement, but both had similar requirements for light and KNO3. Gibberellic acids4+7(GA4+7) induced 100% germination in the dark or light at all temperature regimes. Gibberellic acid3(GA3) was promotive under isothermal conditions, but its effectiveness was enhanced by a shift in temperature from 12 to 22 C. Kinetin or ethephon, each applied alone, had little effect on germination. Ethephon and GA3together induced 100% germination.
Interference of Unicorn-Plant (Proboscidea louisianica) with Cotton (Gossypium hirsutum)
Authors: Mercer Kay L. , Murray Don S. , Verhalen Laval M.
Published: May 2019

Full-season interference from unicorn-plant [Proboscidea louisianica(Mill.) Thell. # PROLO] at densities ranging from 0 to 32 weeds/10 m row was measured on weed and cotton (Gossypium hirsutumL. ‘Westburn M′) parameters in three Oklahoma environments. Linear regression models using log10transformations were superior to linear and comparable to quadratic models in estimating the impact of inter- and intraspecific competition. Weed measurements on an individual plant basis were not reliable indicators of interference. Weed dry biomass, ground cover, and seed capsule production/plot generally increased with increasing weed densities. In the three environments, densities of two, four, and eight weeds/10 m row initially reduced cotton plant height. Maximum height reductions averaged 20, 28, and 43% in the three environments but did not detrimentally affect the mechanical harvest of cotton. As unicorn-plant density (expressed in log10units) doubled (within a range of 1 to 32 plants/10 m of row), lint yield reductions ranged from 84 to 146 kg/ha. Maximum lint yield losses averaged 59, 65, and 74% in the three environments. Transforming lint yield/plot to a percentage of that from weed-free plots resulted in a single quadratic equation applicable over environments. Unicorn-plant at the highest weed density reduced fiber fineness, uniformity, and length, but not fiber strength.
Influence of Flood Interval and Cultivar on Rice (Oryza sativa) Tolerance to Fenoxaprop
Authors: Snipes Charles E. , Street Joe E. , Boykin Deborah L.
Published: May 2019

Five rice (Oryza sativaL.) cultivars were evaluated in the greenhouse for tolerance to fenoxaprop {(±)-2-[4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy]propanoic acid}. Rice was more tolerant to fenoxaprop when flooded at 7 days after spraying, based on trends in reduction of weight of seedling topgrowth. ‘Lebonnet’ was the only cultivar that responded differently when five cultivars were compared. In the field, rice yield was not adversely affected by fenoxaprop applied at 168 g ai/ha and flooded 1 to 10 days after treatment, but yield increased as the time interval between application of 336 g ai/ha and flooding increased. Yield data suggested that flooding should be delayed at least 5 days when rice is treated with the high rate. The cultivar ‘Newbonnet’ was slightly less tolerant than 'Starbonnet’ in the field.
CHI SONO I MINISTRI IN SVEZIA, AUSTRIA E GRAN BRETAGNA
Authors: Segatti Paolo
Published: May 2019

Introduzione

Nel 1966, inNorway: Numerical Democracy and Corporate Pluralism, Rokkan scriveva: «Il corporativismo del sistema didecision-makinga due livelli èimplicito e latente, non formale e istituzionalizzato … La sovrapposizione del personale, l'incrociarsi dei ruoli, le interdipendenze delle strategie ai 2 livellicreano complessi vincoli alle azioni dei partecipanti, e questi possono essere piò efficaci per l'integrazione del sistema di qualunque cornice formale deldecision-makingistituzionale».
INTRODUZIONE
Authors: Urbani Giuliano
Published: May 2019

Introduzione

Questo fascicolo riproduce le relazioni e gli «interventi programmati» che hanno introdotto il convegno annuale della Società Italiana di Scienza della Politica, svoltosi nell'ottobre dello scorso anno, presso l'Istituto Universitario Europeo di Badia Fiesolana, sul tema «Governo e parlamento nel sistema politico italiano». Il sottotitolo del convegno «Questioni teoriche e problemi di analisi empirica» contiene, sia pure in grande sintesi, le principali motivazioni e i relativi obiettivi che ispirarono quella riunione.
PARLAMENTO-ARENA E PARTITI
Authors: Panebianco Angelo
Published: May 2019

Introduzione

Le tesi di Giuseppe Di Palma sul parlamento italiano possono essere discusse da due diverse angolature: si può, da un lato, valutare la descrizione/interpretazione del caso esaminato; si può, dall'altro lato, discutere il quadro teorico proposto e utilizzato. I due aspetti non sono, a giudizio di chi scrive, così strettamente collegati fra loro come potrebbe apparire a prima vista. Si può infatti concordare con molte delle osservazioni di Di Palma sulla evoluzione dei rapporti parlamentari in Italia pur mantenendo riserve sulla prospettiva teorica prescelta (la teoria della istituzionalizzazione nella variante offerta da Polsby).
IL SOTTO-SISTEMA GOVERNO-PARLAMENTO
Authors: Cotta Maurizio
Published: May 2019

Introduzione

Il tema dei rapporti governo-parlamento è stato spesso all'ordine del giorno della discussione sia politica che accademica nell'Italia del secondo dopoguerra. Nell'ultimo quindicennio poi questo interesse si è ulteriormente sviluppato fino a cristallizzarsi in una serie di proposte di ingegneria costituzionale che dovrebbero, nelle intenzioni dei proponenti (operatori politici o studiosi che siano), ovviare alle disfunzionalità del sistema politico italiano.
L'INSTABILITÀ DI GOVERNO IN ITALIA
Authors: Battegazzorre Francesco
Published: May 2019

Introduzione

In un noto contributo sul tema della stabilità governativa pubblicato una quindicina d'anni orsono M. Taylor e V. Herman esprimevano incertezza sul significato della capacità di persistenza dei ministeri, asserendo la necessità di «un ampio studio empirico prima di poter dire che la stabilità governativa è indicatore diuna qualsiasi cosa». In tal modo gli autori intendevano prendere le distanze da un assunto largamente diffuso nella letteratura specialistica sull'argomento, secondo cui la capacità di durata dell'esecutivo è legata significativamente al rendimento del sistema politico e, più in generale, alla stabilità del regime. Benché l'assunto in questione compaia, esplicitamente o implicitamente, anche in alcuni dei più recenti studi sulla stabilità ministeriale, restano comunque dubbi — in assenza dell'analisi empirica suggerita da Taylor e Herman — circa i legami intercorrenti tra persistenza del governo eperformancedel sistema, e non è mancato chi, nell'ambito della disciplina, di tali dubbi si è fatto portavoce. Sartori, per esempio, ha negato in diverse occasioni che un governo stabile (nel senso di duraturo) possa per ciò stesso essere considerato efficiente: «un esecutivo può durare (essere stabile) nell'immobilismo, e anzi durare proprio perché non si muove e non smuove le acque». A questa critica, di natura essenzialmente logica, si aggiunge ora quella — fondata empiricamente — di A. Lijphart, che utilizza dati tratti dal caso francese (IV Repubblica) e da quello nord-irlandese per contestare la tesi secondo cui «la capacità di durata dell'esecutivo è un buon indicatore dell'efficacia del governo e della stabilità del regime democratico». Il punto è quindi tutt'altro che chiarito, e di conseguenza non può sottrarsi all'attenzione dello studioso anche quando l'oggetto d'analisi viene affrontato da un'altra angolatura. Nel nostro caso va detto che indagare sul significato della stabilità o instabilità dell'esecutivo non costituisce l'obiettivo che ci si è proposti qui; tuttavia, data la salienza di questo aspetto del problema per il senso complessivo del lavoro, esso sarà oggetto di una breve trattazione nella parte conclusiva dell'esposizione.
LO STUDIO DEI REGIMI INTERNAZIONALI E LA TRADIZIONE CLASSICA NELLE RELAZIONI INTERNAZIONALI
Authors: Keohane Robert O.
Published: May 2019

Introduzione

Gli studiosi moderni di politica internazionale hanno cercato di individuare le cause della guerra e le condizioni della pace: essi si sono chiesti in che modo gli interessi di Stati sovrani in competizione reciproca e non soggetti ad alcun potere comune possano essere conciliati gli uni con gli altri. I più importanti tentativi di comprensione delle problematiche della pace e della guerra, da parte di studiosi occidentali, sono partiti da tre premesse comuni, che definiscono ciò che Holsti chiama «la tradizione classica» nello studio delle relazioni internazionali: 1) l'oggetto di analisi più appropriato è costituito, appunto, dalle cause della guerra e dalle condizioni della pace/sicurezza/ordine; 2) le principali unità d'analisi sono i comportamenti diplomatici e militari degli unici attori essenziali, gli Stati nazionali; 3) gli Stati operano in un sistema caratterizzato dall'anarchia, ovvero dalla mancanza di una autorità centrale.
L'ANALISI DEI FLUSSI ELETTORALI TRA METODO SCIENTIFICO E DIBATTITO POLITICO
Authors: Draghi Stefano
Published: May 2019

Introduzione

Dopo il 15 giugno e come mai in precedenti elezioni era avvenuto, l'analisi dei flussi elettorali ha assunto un ruolo di rilievo nell'interpretazione dei risultati e nel dibattito politico che ne è seguito. E il modello di Goodman, come in gergo metodologico viene chiamata la tecnica statistica di stima dei flussi di voto, non ha mai ricevuto tanta attenzione presso l'opinione pubblica in generale e, comunque, al di fuori di un ristretto gruppo di studiosi.
The Ultraviolet Continuum in Solar and Stellar Flares
Authors: Phillips K. J. H.
Published: May 2019

Ultraviolet continua observed in IUE spectra of dMc stars in a flaring state are compared with those in solar Hares. There is evidence that, as may be the case with solar flares, stellar-flare continua in particularly the λ < 1683 Å region are due to free-bound transitions in neutral silicon excited by ultraviolet lino emission.
Stellar Flares: Observations and Theory
Authors: Hawley Suzanne L.
Published: May 2019

Photometric and spectroscopic observations of a very large flare on AD Leo are presented. A self consistent model of a flare corona, transition region and chromosphere is developed; in particular the chromospheric temperature distributions resulting from X-ray and EUV irradiation by coronae of various temperatures are determined. The predicted line fluxes in Hγ are compared to the observed line fluxes to find the coronal temperature as a function of time during the flare. This run of temperature with time is then compared with the predictions of an independent theoretical flare model based on a dynamic scaling law (see paper by Fisher and Hawley, these proceedings).
Electron temperatures of flare plasmas from emission line fluxes
Authors: Houdebine E.R. , Butler C.J. , Rodono M. , Panagi P.M. , Foing B.H.
Published: May 2019

We present spectral diagnostics for the fluxes of emission lines, in the spectral range 3600-4400 Å, during the cooling phase of stellar flares on dMe stars. Using these diagnostics, electron temperatures have been computed for flares on AD Leonis, Proxima Centauri and UV Ceti. This preliminary model assumes a single flare loop containing a homogeneous, stationary optically-thin flare plasma.
A Flare on AD Leo observed in Optical, UV and Microwaves
Authors: Byrne P.B. , Gary D.E.
Published: May 2019

We report a simultaneous IUE, VLA and ground-based photometric observation of a flare on the dMe star, AD Leo, on 2nd February 1903. The optical flare was extremely impulsive, lasting in total only about 3 mins. A relatively longlived 6 cm flare was observed with the VLA which was initially 100% polarized. An IUE spectrum, taken ≈ 8 min after the onset of the optical U band flare, shows motu than a factor of 2 increase in the Ha II λ 1640Å emission line. The other mid-transition region lines such as C IV λλ154B/52Å show almost no response.
Balmer lines and Continuum Emission for two Flares of the dMe Star Gliese 729
Authors: Falchi A. , Falciani R. , Smaldone L.A. , Tozzi G.P.
Published: May 2019

It has been shown for solar flares (Donati-Falchi et al. 1985) that the continuum emission at the Balmer discontinuity (the blue “pseudo-continuum”) is a very sensitive tool to determine the electron density. In order to use the same interpretative scheme for stellar flares (Falchi et al. 1988), spectroscopic observations of various flare stars have been performed in June 1987 at ESO observatory (Chile). In this paper we report the analysis of spectra of the star n. 729 (V 1216 Sgr) of the Gliese catalog.
Spectral Observations of a Large Stellar Flare
Authors: Robinson R.D.
Published: May 2019

High time resolution, moderate spectral resolution spectra were taken during the decay phase of a ΔU > 3 magnitude flare on the dM5.5e star Wolf 424. This flare shows intense, broad Balmer line emission with extended wings, narrow Call lines and numerous weak emission lines from neutral and singly ionized metals. The time history shows substantial, short-lived enhancements in the line emission. These variations are not always seen in association with continuum enhancements.
An analysis of the continuum light in the 3500 – 8500Å region from a flare observed on the dwarf M star Gliese 234AB (= V577 Mon)
Authors: Doyle J.G. , van den Oord G.H.J. , Butler C.J.
Published: May 2019

Relative energies are given for the U, B, V, R and I bands for a-3.8 magnitude U-band flare observed on the dwarf dMe star Gl 234 AB on 28 Feb 1985. This flare had a 45 second rise time and 20 minute decay time. The total flare energy from all five bands during the flare was 7 1031 erg, 34% of this total was from the U-band and 20% from the two near infrared R and I bands. The energy density (per frequency interval) implied a rising continuum towards the red, however this only lasted for approximately 20-40 seconds, i.e. during the impulsive phase, after-which the excess flare emission could not be detected in tlie near infrared bands. Of the various models fitted to the flare data (i.e. optical synchrotron, bound-free emission and free-free emission), bound-free emission seems the most promising.
A giant X-ray flare from a B9 + Post-T Tauri system detected by EXOSAT
Authors: Tagliaferri G. , Giommi P. , Angelini L. , Osborne J.P. , Pallavicini R.
Published: May 2019

We report the serendipitous discovery by EXOSAT of a flaring X-ray source in the field of the Seyfert type I galaxy III ZW 2. We identify this source with the visual binary HD 560 (B9V + G5Ve) and argue that virtually all of the observed X-ray flux, including the flare, came from its late-type component (HD 560 B). Optical studies have lead to the identification of HD 560 B as a post-T Tauri star. Since these stars are difficult to detect by optical methods, X-ray observations may prove to be the best way to identify them.