bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling the Influence of Postdirected Sethoxydim on Corn Yields
Authors: Smart James R. , Weiss Albert , Mortensen David A. 
Published: July 2010

AbstractPostdirected sethoxydim 2‐[1‐(ethoxyimino)butyl]‐5‐[2‐(ethylthio) propyl]‐3‐hydroxy‐2‐cyclohexen‐1‐one, used to control monocot weeds, is known to reduce corn (Zea mays L.) yields. The objective was to develop an integrative model combining a growing plant with the effect of sethoxydim. CERES‐Maize (version 1.0) was modified to respond to herbicide‐induced grain yield reductions by incorporating a herbicide stress factor and the stress duration into calculation of the daily biomass production. Herbicide stress was defined as the difference in net photosynthesis between treated and nontreated plants. A seasonal herbicide stress factor (0–1) was determined from field measurements of treated and nontreated corn yields as a function of sethoxydim concentration (110 and 220 g a.i. ha−1) for all application dates. This factor was modified to reflect the period of the herbicide stress duration by scaling it to the fraction of time the sethoxydim was active. Field experiments were conducted using four corn hybrids (Pioneer 3475, 3379, 3377, and 3183). Data from 1988 field experiments were used to calibrate the genetic inputs for each hybrid and develop a herbicide stress relationship. The data collected in 1989 were used to validate the modifications made to CERES‐Maize. Overall, the model predicted that sethoxydim use would reduce corn yields, and this trend was consistent with independently measured field data. Based on the ratio of treated to nontreated yields for simulations and measurements, the model predictions underestimated the sethoxydim effect for the hybrids 3475, 3379, and 3183.
Time of Salt Stress Affects Growth and Yield Components of Irrigated Wheat
Authors: Francois Leland E. , Grieve Catherine M. , Maas Eugene V. , Lesch Scott M. 
Published: July 2010

AbstractSalt tolerance of wheat (Triticum aestivum L.) is known to change during different stages of growth. The effects of salinity on growth and yield components of wheat at different stages of growth were determined in a 2‐yr field plot study at Brawley, CA. Four salinity levels were imposed on a Holtville silty clay [clayey over loamy, montmorillonitic (calcareous), hyperthermic Typic Torrifluvent] by irrigating with waters salinized with NaCl and CaCl2(1:1 w/w). Electrical conductivities of the irrigation waters were 1.4, 10.0, 20.0, and 30.0 dS m−1 in 1989, and 1.4, 8.0, 16.0, and 24.0 dS m−1 in 1990. The three irrigation treatments were (i) salinity imposed throughout the growing season, (ii) saline irrigation initiated after terminal spikelet differentiation (TSD), and (iii) saline irrigation discontinued at TSD. Growth and yield components measured were straw yield, total above ground biomass, number of spikelets per spike, number of kernels per spike, individual kernel weight, number of tillers per plant, and number of tiller spikes. Continuous salinity throughout the growing season significantly reduced all growth and yield components. Salinity imposed prior to TSD reduced the number of spikelets per spike and the number of tillers per plant, whereas salinity imposed after TSD significantly reduced only kernel number and weight. In general, the effect of salinity appears to be most pronounced on the yield components that are growing or developing at the time the salt stress is imposed. Total grain yields were maintained when moderately saline irrigation waters were substituted for good quality water during part of the growing season.
Rye Residue Geometry for Faster Corn Development
Authors: Fortin M.‐C. , Hamill A. S. 
Published: July 2010

AbstractWinter cereals used as cover crops in corn (Zea mays L.) production physically modify the soil‐plant environment. Springtime killing of the cover crops with herbicides leaves surface residues either standing, flat, or a combination of the two at corn planting. This study was conducted to verify how standing rye (Secale cereale L.) residue affected soil temperature, soil water, and corn development compared with flat rye residue in a sandy loam in Harrow, ON, in 1990, 1991, and 1992. In the 3 yr, volumetric soil water content was similar in both treatments, but seed zone daily maximum temperatures were higher under standing than under flat residue. Corn development in standing residue was faster (2 to 3 d) compared with flat residue, except if seed zone maximum temperatures were regularly in the 28 to 32° range for both treatments, such as in 1991. During vegetative stages in 1990 and 1992, plants in the standing residue were taller than plants in the flat residue. Most of these height differences were related to differences in development that were related to soil temperature. In 1991, however, which was a hot and dry year, phyllochron values indicate that developmental rates under both treatments were affected by a factor other than temperature, most likely by a lack of soil water. In 2 of 3 yr, when seed zone temperatures were often below the optimal range for corn development, standing rye residue resulted in faster plant development than flat rye residue due to a warmer seed zone. Residue treatments did not affect yield.
Grain Yield, Kernel Weight, and Disease Responses of Winter Wheat Cultivars to Chloride Fertilization
Authors: Engel Richard E. , Eckhoff Joyce , Berg Robert K. 
Published: July 2010

AbstractWheat yields in the Great Plains are frequently improved by potash (0‐0‐60 N‐P‐K) application on soils with seemingly abundant supplies of available K. The CI component in this fertilizer may cause many of the observed yield responses. Field research was undertaken to determine the effects of CI on grain yield, plant CI, kernel weight and growth rate, and foliar disease and/or disease‐like symptoms of winter wheat cultivars. Two sites with five CI levels (0, 22, 45, 90, and 135 kg ha−1) and two cultivars (Redwin, Cree) were used in 1988. Seven sites with two CI levels (0 and 45 kg ha−1) and six cultivars (Redwin, Cree, Weston, Manning, QT542, Neeley) were used from 1991 to 1992. Chloride increased yield by an average of 267 kg ha−1 (7%) at seven responsive sites. Size of yield response to CI was generally not affected by cultivar selection, but differed greatly with location. Whole‐plant CI analyses were useful in discriminating between yield responsive (≤ 3.0 g kg−1) and nonresponsive (>3.0 g kg−1) sites to CI fertilization. Improved CI nutrition enhanced plant development, increase immature kernel weights, and accelerated kernel growth during the grain‐fill period. Fertilizer CI increased mature kernel weights, up to 17%, at eight sites. Kernel weight was the most important yield component affected by CI. Physiological leaf spot in Redwin and Manning, flag leaf senescence in Weston and QT542, powdery mildew (Erysiphe graminis DC. f. sp. tritici Em. Marchal), and leaf rust (Puccinia recondita Roberge ex Desmaz. f. sp. tritici) were suppressed by fertilizer CI. These phenomena may explain in part the yield responses to CI; however, yield response to CI occurred even without foliar disease and disease‐like suppression.
Seeding Rate and Kill Date Effects on Hairy Vetch‐Cereal Rye Cover Crop Mixtures for Corn Production
Authors: Clark Andrew J. , Decker A. Morris , Meisinger John J. 
Published: July 2010

AbstractHairy vetch (Vicia villosa Roth) fixes N for corn (Zea mays L.) production, and cereal rye (Secale cereale L.) accumulates soil N to reduce potential N losses. The objective of this research was to identify optimum seeding rates of vetch‐rye cover crop mixtures at Coastal Plain and Piedmont locations in Maryland. Mixtures evaluated were 14, 21, and 28 kg vetch ha−1, and 47 or 94 kg rye ha−1 in complete factorial combination. Pure vetch, rye, and no cover crop were used as controls. Cover crops were killed in early April (early kill) and early May (late kill), followed by no‐till corn without fertilizer N. Corn grain yields were significantly higher following late‐killed covers. Coastal Plain grain yields ranged from 3.1 to 7.0 Mg ha−1 and Piedmont yields ranged from 5.2 to 10.7 Mg ha−1. Within each kill date, corn yield was highest following vetch, lowest following rye, and intermediate following all six mixtures. Cover crop yield increased by 160% in the Piedmont and 83% at the Coastal Plain location when kill was delayed. Except for pure rye, N content was 1.6 to 2 times greater by the late kill date. Total N content was equal for all vetch‐rye mixtures at each date and within location, ranging from 74 to 109 kg ha−1 for early kill, and from 136 to 219 kg ha−1 for late kill. Carbon‐to‐nitrogen ratios (C/N) were 25:1 for all mixture combinations at the Piedmont location and for mixtures with low rye component at the Coastal Plain location. The best seeding rate mixture for corn production was 21 kg vetch ha−1 and 47 kg rye ha−1. The vetch‐rye mixture can scavenge potentially leachable N, while maintaining corn yields by adding fixed N to the cropping system.
Sorghum Grain Yield Reductions Caused by Duration and Timing of Freezing Temperatures
Authors: Staggenborg Scott A. , Vanderlip Richard L. 
Published: July 2010

AbstractManagement practices, as well as below‐normal temperatures that occur late in the growing‐season, can delay grain sorghum [Sorghum bicolor (L.) Moench] maturity in the northern Great Plains. Delaying maturity increases the probability of a freeze occurring before the crop reaches physiological maturity. Studies were conducted during 1988 and 1989 using greenhouse‐ and field‐grown plants in Kansas to determine caryopsis weight and test weight reductions from exposure to subfreezing air temperatures. Treatments of 0, −2, and −4°C air temperatures for 2, 4, and 8 h were conducted in a growth chamber when developing grain had attained approximately one‐half of its maximum weight. A second experiment studied the effects of exposure to −2°C for 4 h at different stages of grainfill. Caryopsis weights were progressively reduced as air temperature was reduced from 0 to −4°C. Effects of exposure time to subfreezing air temperatures on caryopsis weight were not consistent from year to year. Air temperatures of −2°C or lower reduced test weight of grain from field‐grown plants, whereas only exposure to −4°C reduced test weight of grain from greenhouse‐grown plants. Exposure to −2°C for 4 h reduced caryopsis weights 81% at 200, 57% at 300, 25% at 450, and 3% at 600 growing degree days (GDD, base temperature 5.7°C) after anthesis (maturity = 850 GDD). Test weight response was similar to caryopsis weight response with test weights from plants exposed to freezing temperatures at 200 and 300 GDD after anthesis lower than at other treatment times or the control. These results indicate that minimum air temperature is the primary factor in determining caryopsis weight and test weight when grain sorghum is exposed to subfreezing air temperatures.
Conductimetric Measurement of CO2 Concentration: Theoretical Basis and Its Verification
Authors: Baker John M. , Spaans Egbert J. A. , Reece Clive F. 
Published: July 2010

AbstractAtmospheric CO2 is important to plant growth and also plays a key role in the global energy balance. Thus, there are needs for reliable methods for measuring CO2 concentrations, [CO2]. One approach has been the conductimetric method, where sampled gas is bubbled through deionized water. Some of the CO2 in the air dissolves and ionizes, causing an increase in solution electrical conductivity. The method is inexpensive relative to other techniques, but usage has been limited, possibly due to its apparently empirical basis and suggestions that it must be frequently checked to correct for shifts due to temperature and other effects. We have derived the fundamental basis for the method and equations that allow [CO2] to be directly determined from measurements of solution electrical conductivity and temperature, with no empirical calibration. The equilibrium constants and ionic conductivities that are used are temperature dependent, but those dependences are well known and easily computed. The approach was tested with a system in which the conductivity was measured with time‐domain reflectometry (TDR), using a coaxial cell through which the aerated water was circulated. To maximize sensitivity, a long cell (1 m) of low impedance (19.3 Ω) was used. The system was compared against an infrared gas analyzer (IRGA) over a range of [CO2] from 0 to 1000 μmol mol−1, at three different temperatures (5, 19, and 34°C). Regression of [CO2] calculated directly from the conductivity measurements against the IRGA measurements produced a slope of 1.00, r2 of 0.997 and a standard error of estimate of 16.1 μmol mol−1. Resolution was approximately 1 to 2 μmol mol−1, too large for micrometeorological flux measurements but sufficient for many monitoring applications. The approach should work with any accurate device for measuring solution conductivity.
Winter Rye as a Cover Crop Following Soybean under Conservation Tillage
Authors: Kessavalou Anabayan , Walters Daniel T. 
Published: July 2010

AbstractRotation of corn (Zea mays L.) with soybean [Glycine max (L.) Merr.] provides certain economic and environmental advantages over monoculture corn. Low soybean residue production and persistence, however, promote potentially excessive soil erosion following soybean harvest. An irrigated field experiment was conducted in eastern Nebraska for 4 yr (1990–1993) under various tillage treatments and N rates to evaluate the effects of a winter rye (Secale cereale L.) cover crop following soybean on (i) rye dry matter yield, (ii) surface residue cover for erosion protection, and (iii) corn establishment and production. The soil was a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls). Treatments were (i) no‐tillage and disk tillage; (ii) corn following soybean with a winter rye cover crop (CBR), corn following soybean without rye (CB) and corn following corn (CC); and (iii) 0, 50, 100, 150, and 300 kg N ha−1 (applied to corn). Rye aboveground dry matter yield, surface residue cover, and corn yield parameters were estimated. Rye dry matter yield ranged from 0.25 to 2.9 Mg ha−1 and was influenced by tillage, N rate, and weather conditions in different years. During the years of high rye dry matter yield, presence of rye in the corn‐soybean system gave approximately 16% additional surface residue cover prior to planting through cultivation, compared with soybean residue alone. Surface cover by rye and soybean residues in CBR was equivalent to corn residue in CC under both disk and no‐till management. In 1 of the 3 yr, corn plant population and grain yield were reduced following rye (CBR) compared with the no rye system (CB), possibly due to apparent allelopathic effects related to the age of rye. No significant difference in N response was observed between CBR and CB corn yields. In general, rotation of corn with soybean (with and without rye) resulted in an increase of approximately 27% in corn grain yield and N uptake over continuous corn. During the years of high rye dry matter production, rye accumulated approximately 45 kg N ha−1 through aboveground dry matter. Overall, including a winter rye cover crop in the corn‐soybean rotation system was beneficial.
Fractionation and Characterization of a Soil Polysaccharide Extract
Authors: Thomas R. L. , Mortenson J. L. , Himes F. L. 
Published: July 2010

AbstractSoil polysaccharides from the Brookston soil were extracted with hot water and purified by precipitation, dialysis, and de‐ proteinization with chloroform. The purified polysaccharides were fractionated on a column of diethyaminoethyl‐cellulose by elution with phosphate buffers and an increasing gradient of NaOH concentration. The five fractions obtained could not be distinguished on the basis of their monosaccharide composition. Differences could be detected in the nitrogen and uronic acid contents and the electrophoretic mobility of the five fractions. The electrophoretic mobility as determined by free‐boundary electrophoresis could be related to the uronic acid content of each fraction. The electrophoretic patterns indicated that all five fractions were still not homogeneous preparations.
Estimating Losses of Efficacy Due to Pesticide Biodegradation in Soil: Model Simulations
Authors: Shelton Daniel R. , Doherty Michael A. 
Published: July 2010

AbstractA model was developed for describing rates of pesticide‐substrate biodegradation, accounting for bioavailability and microbial growth. The model was used to simulate losses of efficacy for soil‐applied pesticides. The model requires rate constants for rapid sorption‐desorption to and from soil surfaces (k1/k‐1 = Kd1); diffusion into and out of soil aggregates‐organic matter particles (k2/k‐2 = Kd2); microbial growth [yield (Y), maximum growth rate (µmax), half‐saturation growth constant (Ks), and initial biomass concentration (X0)]; initial mass of substrate (s0); and gravimetric water content (θg). Simulations of microbial growth and substrate depletion were conducted assuming no sorption (aqueous solution), sorption to soil surfaces only, and sorption in conjunction with diffusion. The time required to achieve a soil solution concentration of 1 µg mL−1 was defined as a hypothetical loss of efficacy (LE1). Certain relationships were consistently observed, regardless of sorption or diffusion: LE1 was found to be related to Ks linearly, to X0 logarithmically, to µmax geometrically, and to initial pesticide‐substrate concentration (S0) nonlinearly. Sorption to soil surfaces resulted in decreased equilibrium soil solution concentration (Se), depending on the magnitude of θg and Kd1. Rates of biodegradation‐growth were a function of Se, as opposed to total (soluble + sorbed) concentration. Sorption coupled with diffusion decreased both Se and time‐dependent availability, resulting in slower rates of biodegradation. In general, larger values of S0 resulted in faster rates of biodegradation, i.e., decreased the time required for a loss of efficacy.
Archibald Menzies (1754–1842), an early botanist on the northwestern seaboard of North America, 1792–1794, with further notes on his life and work
Authors: GROVES ERIC W. 
Published: July 2010

ABSTRACT:This paper includes a short biography of Menzies and an outline of the historical events on the northwest Pacific coast leading up to Vancouver's voyage. A table listing the botanical visitors to that area prior to 1792 is given followed by a résumé of the evolution of Menzies's journal. Sources used in compiling the chronology of his movements during Vancouver's voyage are then set down, ending the section with an account of Menzies's own visit, 1792–1794. His method of plant collecting is discussed along with an account of his collections and their subsequent disposal. The paper concludes with details of Menzies's later life, his connection with other botanists of the day, and an assessment of his achievements.
Pressure loss mechanism analysed with pipe turbulence theory and friction coefficient prediction in labyrinth path of drip irrigation emitter
Authors: Yunkai Li , Peiling Yang , Honglu Liu , Tingwu Xu , Haisheng Liu 
Published: July 2010

AbstractA labyrinth path is the predominant pattern for drip irrigation emitters at present. It is very important to explore the pressure loss mechanism for the labyrinth path. This paper took the Minkowski fractal curve flow path, a special labyrinth flow path, as an object to study the pressure loss mechanism of fractal flow paths with dimension analysis technology and rough pipe turbulence theory. The results of the research showed that the Reynolds number has an insignificant effect on the friction coefficient of the flow path, which can be ignored. The friction coefficient was primarily related to the hydraulic radius, fractal dimension and unit length of the fractal flow path. Under the pressure of 15–150 kpa within the fractal flow path, the flow was completely turbulent. Hence, constructing the fractal flow path is an effective approach to simultaneously enhancing the hydraulic performance and anti‐clogging performance. The critical Reynolds number for flow twist was moved earlier because of the continuous disturbance within the flow path of the emitters. Copyright © 2010 John Wiley & Sons, Ltd.
Glycosidic intermediates identified in 1H MR spectra of intact tumour cells may contribute to the clarification of aspects of glycosylation pathways
Authors: Grande Sveva , Palma Alessandra , Luciani Anna Maria , Rosi Antonella , Guidoni Laura , Viti Vincenza 
Published: July 2010

AbstractThe glycosylation process, through the addition of carbohydrates, is a major post‐translational modification of proteins and glycolipids. Proteins may be glycosylated in either the secretory pathway leading to N‐linked or O‐linked glycoproteins or as nucleocytoplasmic glycosylation that targets only single proteins involving a single β‐linked N‐acetylglucosamine. In both cases, the key precursors are the uridine diphospho‐N‐acetylhexosamines synthesised by the hexosamine biosynthetic pathway. Furthermore, uridine diphospho‐N‐acetylglucosamine participates in the biosynthesis of sialic acid. In this work, we propose MRS for the detection of uridine diphospho‐N‐acetylhexosamines visible in high‐resolution MR spectra of intact cells from different human tumours. Signals from the nucleotide and amino sugar moieties, including amide signals observed for the first time in whole cells, are assigned, also taking advantage of spectral changes that follow cell treatment with ammonium chloride. Finally, parallel changes in uridine diphospho‐N‐acetylhexosamines and glutamine pools, observed after pH changes induced by ammonium chloride in the different tumour cell lines, may provide more details on the glycosylation processes. Copyright © 2010 John Wiley & Sons, Ltd.
Characterization of an ATP-regulated DNA-processing enzyme and thermotolerant phosphoesterase in the radioresistant bacterium Deinococcus radiodurans
Authors: Kota Swathi , Kumar C. Vijaya , Misra Hari S. 
Published: July 2010

A multiprotein DNA-processing complex identified from Deinococcus radiodurans exhibits uncharacterized ATP-sensitive nuclease functions. DR0505 was one of the 24 polypeptides identified from the complex. It contains two 5′ nucleotidase motifs, one is at the C-terminal end of the N-terminal CPDD (calcineurin phosphodiesterase domain), with the second at the C-terminal end of the protein. Recombinant DR0505 showed both phosphomonoesterase and phosphodiesterase activities with chromogenic substrates, showing higher affinity for bis-(p-nitrophenyl) phosphate than for p-nitrophenyl phosphate. The enzyme exhibited pH optima ranging from 8.0 to 9.0 and metal-ion-dependent thermotolerance of esterase functions. Both mono- and di-esterase activities were stable at temperatures up to 50 °C in the presence of Mg2+, whereas monoesterase activity was observed at temperatures up to 80 °C in the presence of Mn2+ and up to 50 °C with Ca2+. The purified enzyme showed 5′ nucleotidase activity on a wide range of natural mononucleotides including cyclic mononucleotides and 8-oxo-GMP. DR0505 showed a nearly 7-fold higher activity on ADP than AMP, but this activity was inhibited with ATP. Interestingly, DR0505 also showed single-stranded endonuclease and 3′→5′ exonuclease activities on both single-stranded and double-stranded DNA-substrates. Unlike for the exonuclease activity, the single-stranded endonuclease activities observed on stem-loop substrates and at the single strand–double-strand junction in forked-hairpin substrates were not inhibited with ATP. These results suggested that DR0505 is an ATP-regulated DNA-processing enzyme and a thermotolerant esterase in vitro. We therefore suggest possible roles of this enzyme in nucleotide recycling and DNA processing, which is required for efficient double-strand break repair and the high radiation tolerance observed in D. radiodurans.