bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil Water and Population Influence on Hybrid Sunflower Yield and Uniformity of Stand1
Authors: Prunty Lyle 
Published: July 2010

AbstractSunflower (Helianthus annuus L.) hybrids do not respond identically to agronomic and environmental variables. The present study was conducted to quantify the influence of soil water potential and plant population on oilseed sunflower hybrids ‘Dahlgren 704’, ‘USDA 894’, and ‘Interstate 907’. Desire to refine knowledge of yield relationships was one motivation for the study, but a deeper stimulus was the need for basic knowledge of the detailed nature of sunflower stands. Hybrids were planted at four populations at two North Dakota sites in 1980. One site had Maddock (sandy, mixed Udorthentic Haploboroll) and Gardena (coarse‐silty, mixed pachic Udic Haploboroll) soils. This location received irrigation treatments limiting soil water potentials to minimums of ‐35, ‐70, and ‐105 J kg‐−1. The second site had Bearden (fine‐silty, frigid Aeric Calciaquoll) soil and was not irrigated. Yield increased with soil water potential from 201 g m−2 at – 105 J kg−11 to 284 g m−2 at ‐35 J kg−1. Dryland yields were 200, 179, and 164 g m−21 for hybrids 894,704, and 907. Population did not influence yields. However, irrigated and nonirrigated stand loss percentages increased with population at 0.8 and 2.2% per plant per square metre, respectively. Knowledge of the threshold population for stand loss provides a rationale for selection of population in the absence of yield differences because significant stand loss indicates a possibly undesirable level of intraspecific competition. Guidelines for irrigation scheduling for sunflower by use of tensiometers are now on a sounder experimental basis. Hybrids similar under irrigation yielded differently under dryland conditions.
Shrinkage of Soybean Roots1
Authors: Taylor H. M. , Willatt S. T. 
Published: July 2010

AbstractIt has been postulated that shrinkage and subsequent rehydration of roots growing in soil cause significant variations in root‐soil contact resistances to ion and water movements. The research reported here used neutron radiography to evaluate shrinkage of soybean (Glycine max L. Merr. cv. Bethel) roots growing in soil as hydrated plants became severely wilted. The first experiment evaluated the amount of shrinkage possible for soybean roots as their water potential decreased from 0 to −1.34 MPa. The roots were immersed in polyethylene glycol solutions (PEG 6000) of 0, −0.37, or −1.34 MPa. Root diameters were measured as functions of time and distance from the root tip. Under controlled temperature conditions, roots did not change diameter in the 0 MPa solution but shrank to 0.97 of the original diameter in 2 h when immersed in the −0.37 MPa PEG solution and to 0.7 when immersed in the −1.34 MPa solution for 2 h. The second experiment used neutron radiography to evaluate taproot diameter of three soybean plants located in an unclassified sandy loam soil as hydrated plants lost water and wilted severely. Reproducibility with time of diameter readings on each section of root in the neutron radiography technique was about ± 0.02 mm ( ± 2%) on these three plants. When three hydrated plants wilted severely but recovered overnight, their roots shrank less than 0.02 mm (2%). These results indicated that shrinkages of plant roots growing in moist soil probably cause negligible increases in root‐soil contact resistance. These results do not rule out the possibility that roots will shrink appreciably as the soil around them dries substantially.
Simple Simulation Models for Yield Prediction Applied to Alfalfa in the Northeast1
Authors: Fick Gary W. 
Published: July 2010

AbstractThe effect of model elaboration upon predictive accuracy has not been adequately studied for simulation models of crop production. A set of eight simple dynamic simulation models of alfalfa (Medicago sativaL.) production were formulated to determine the relative contribution of six factors to model accuracy. The six factors were production potential (maximum yields in each harvest), heat summation, nonlinear temperature effects, soil water budgets, regrowth potential (cutting management and root reserves), and a general soil production factor based on available soil water in the root zone at field capacity. The soils considered were a Glossoboric Hapludalf, an Aqueptic Fragiudalph, and a Dystric Eutrochrept. The factors were compared individually and in selected combinations by regressing field observations on model predictions. The field observations represented yields measured across three soils, 2 years, and three harvest managements in New York (n = 60). The best model included factors for production potential, heat summation, soil water holding capacity, and cutting management (r2= 0.758). Relatively simple soil water budgets contributed little to model accuracy beyond what was accounted for by a general ranking of soils by water holding capacity in the humid environments. Representing the four factors of production potential, heat summation, soil water holding capacity, and management in a simulation model appears to provide a simple basis for formulating base‐line models.
Sod‐Seeding of Ladino Clover and Alfalfa as Influenced by Seed Placement, Seeding Date, and Grass Suppression1
Authors: Mueller J. P. , Chamblee D. S. 
Published: July 2010

AbstractThe competition between a grass sward and a legume seedling limits legume growth when sod‐seeding legumes into perennial grass swards. The objective of this research was to evaluate the effects of time of seeding, grass suppression, and seed placement on the spring establishment of ladino clover (Trifolium repensL.) and alfalfa (Medicago sativaL.) in a tall fescue (Festuca arundinaceaSchreb.) sod. Field experiments were conducted during 4 years (1978 to 1981) on a Cecil clay loam soil (clayey, kaolinitic, thermic Typic Hapludult) in North Carolina. Seeds were drilled or placed on the soil surface with and without broadcast applied paraquat (1, 1'dimethyl‐ 4, 4′‐bipyridinium ion) at 0.28 kg a.i. ha−1on two dates (mid‐February or mid‐March) in a randomized complete block design with a 2 ✕ 2 ✕ 2 factorial arrangement. Legume stands and dry matter yields were measured. Drilling legume seeds vs. surface placement resulted in two to four times as many seedlings initially established and up to 2000 kg ha−1more legume yield during the first season. Nevertheless, satisfactory stands were eventually obtained from surface seeding ladino in late February in 3 of 4 years. Planting in February resulted in better stands and yields of clover than March plantings in 3 of 4 years. Using paraquat for sod suppression often resulted in significant advantage when clover was seeded at the later (March) date. Alfalfa produced very low yields during the first season under all treatment variables (usually one or two harvests) and did not appear to compete well with the tall fescue sod when spring seeded. The highest yields obtained during these studies ranged from 795 to 4610 kg ha−1.
Estimating Silking and Maturity Dates of Corn for Large Areas1
Authors: Daughtry C. S. T. , Cochran J. C. , Hollinger S. E. 
Published: July 2010

AbstractKnowledge of when critical crop stages occur and how the environment affects them should provide useful information for crop management decisions and crop production models. This research evaluated two sources of data for predicting dates of silking and physiological maturity of corn (Zea maysL.). Initial evaluations were conducted using data of an adapted corn hybrid grown on a Typic Agriaquoll at the Purdue University Agronomy Farm from 1979 to 1981. The second phase extended the analyses to large areas using data acquired by the Statistical Reporting Service of USDA for crop reporting districts (CRD) in Indiana and Iowa from 1969 to 1980. Several thermal models were compared to calendar days for predicting dates of silking and physiological maturity. Mixed models which used a combination of thermal units to predict silking and days after silking to predict physiological maturity were also evaluated. At the Agronomy Farm the models were calibrated and tested on the same data. For each CRD the models were calibrated using 4 or 5 years of data and tested using 7 different years of data. The thermal models were significantly less biased and more accurate than calendar days for predicting dates of silking. Differences among the thermal models were small. Significant improvements in both bias and accuracy were observed when the mixed models were used to predict dates of physiological maturity. The results indicate that statistical data for CRD can be used to evaluate models developed at agricultural experiment stations.
Crop Water Stress Index, Soil Water, and Rubber Yield Relations for the Guayule Plant1
Authors: Nakayama F. S. , Bucks D. A. 
Published: July 2010

AbstractCanopy temperature measurements based on remote infrared thermometric techniques and atmospheric vapor pressure deficits from meteorological parameters were used for developing crop water stress indices (CWSI) for three varieties of the drought‐tolerant guayule plant (Parthenium argentatumA. Gray). Measurements were conducted on a coarse‐loamy, mixed, hyperthermic Typic Calciorthids soil. Six irrigation levels were used to obtain relations between plant stress and soil water content, and also rubber yield. The results of the initial phase of a long‐term experiment showed that the CWSI values were related negatively to the fraction of available soil water in the 0 to 1.8 m of soil depth. The CWSI of the 510‐day‐old perennial plant taken during the actively growing period could also be inversely related to the rubber yield.
Four‐Year Response of a Kentucky Bluegrass‐Red Fescue Turf to Plant Growth Retardants1
Authors: Dernoeden Peter H. 
Published: July 2010

AbstractMost research on plant growth retardants (PGR's) for turfgrasses has involved single and occasionally two annual PGR applications. The objectives of this study, however, were to evaluate longer term effects of PGR usage on turf density, quality, and canopy height by applying various rates of ethephon [(2‐chloroethyl) phosphonic acid], flurprimidol {α‐(1‐methylethyl‐α‐[4‐(trifluroro‐methoxy) phenyl]‐5‐pyrimidinemethanol}, mefluidide {N‐[2,4‐dimethyl‐5[[(trifluoro‐methyl)‐sulfonyl]amino]phenyl] acetamide}, and MBR 18337 (MBR) [N‐(2ethylthio)‐2‐(trifluromethyl)phenyl methanesulfonamide] twice annually, for 4 consecutive years to a Kentucky bluegrass (Poa pratensisL.)‐red fescue (Festuca rubrassp. rubraL.) turf grown on a Chillum silt loam soil (fine‐silty, mixed, mesic Typic Hapludult). The field data presented were combined over months and years for 1980, 1981, and 1982. Furthermore, 8 months following the final PGR application, turf plugs collected from field plots were evaluated for tiller and thatch production, leaf growth, and root recuperative potential. All PGR's reduced canopy height significantly from June to September. Mefluidide and MBR provided the most rapid growth suppression; however, flurprimidol provided a longer period of growth inhibition. Mefluidide and MBR caused leaf yellowing and necrosis shortly following application. Discoloration elicited by flurprimidol appeared several weeks following application in the form of leaf tip necrosis, but not death of entire leaves. Flurprimidol treated turf also developed an undesirable blue‐green color during periods of heat and drought stress. Ethephon treated turf generally possessed a dark green color during summer. Between September and April, however, many ethephon treated plants developed necrotic sheaths. Ethephon caused elongation of internodes, and crowns of many plants were elevated several mm above the soil surface. Crown elevation gave the turf a ‘puffy’ quality and resulted in a large reduction of verdure when mowed. Mefluidide and MBR reduced turf density, which resulted in a severe infestation of crabgrass (Digitariaspp.). Crabgrass infestation was not a problem in flurprimidol and ethephon treated turf. Mefluidide and MBR effectively suppressed seedhead production; whereas, flurprimidol (2.2 and 3.4 kg a.i. ha−1) enhanced their production. Flurprimidol treated turf had more tillers and leaves than turf treated with other PGR's. Signficantly higher root weights were associated with flurprimidol G (2.2 and 3.4 kg ha−1) treated turf; however, root weight was positively correlated (r=0.80*, significant at the 0.05 level) with tiller number. Data revealed that two annual applications of the PGR's evaluated caused adverse effects that would limit their use on intensively managed turf. There were, however, no deleterious effects of PGR usage upon tiller and root recuperative potential of the Kentucky bluegrass‐red fescue turf.
Leaf Area and Dry Matter Accumulation of Wheat Following Forage Removal1
Authors: Dunphy D. J. , Holt E. C. , McDaniel M. E. 
Published: July 2010

AbstractWheat (Triticum aestivum L. em Thell.) is commonly both grazed for forage and harvested for grain in the Southern Great Plains of the USA. Information is needed on the plant characteristics affected by forage removal and their relationships to grain yield. Leaf area index was measured at 0,1, and 2 weeks following forage removal in 3 years of field experiments. The soil type was a member of the fine, montmorillonitic thermic family of Vertic Albaqualfs. Leaf area and dry matter present at anthesis were also recorded. Treatments consisted of taking the final forage harvest for two cultivars at the early joint, mid‐joint, or late joint stage of development but without removing terminal meristems. All treatments were harvested for grain at maturity, including a check that was not harvested for forage. Total LAI at anthesis averaged over varieties for the first 2 years, decreased from 1.40 to 0.79 when the final forage harvest was delayed from early to late joint. Total dry matter present at anthesis averaged over all years and varieties decreased from 491 to 326 g m−2. Leaf area duration from jointing to anthesis, the product of the average leaf area present and the number of days in the sampling period, averaged 42.9 days m2m−2 for the early joint treatment, compared to 15.8 days m2m−2 for the plants harvested at late joint. These factors were highly correlated (r = 0.64 to 0.88) with grain yield in all 3 years for both cultivars. The data indicate that when the leaf area produced during the vegetative and jointing stages was harvested as forage, grain yield was limited by the potential of the plant to rapidly produce new leaf area and prevent tiller senescence during the period between jointing and anthesis.
Effects of Salinity on Seashore Paspalum Turfgrasses1
Authors: Dudeck A. E. , Peacock C. H. 
Published: July 2010

AbstractIncreased need for salt tolerant grasses continues due to increased restrictions on limited water resources and to salt water intrusion into groundwater. Seashore paspalum (Paspalum vaginatum Swartz.) is used in Australia as a salt tolerant turfgrass, and cultivars are commercially available in the USA. The purpose of this investigation was to document the glasshouse response of four Seashore paspalum turfgrasses to solution cultures differentially salinized with synthetic sea water. A sea salt mixture was added to half‐strength Hoagland's number 2 nutrient solution to provide six salinity treatments ranging from 0.9 to 39.7 dS m−1. A split‐plot design with five replications was utilized to study salinity as the main plot effect and grass as the sub‐plot effect. Turfgrasses differed markedly in salt tolerance. Based on inverse regression analyses, the most salt tolerant experimental selection was FSP‐1 with 50% of its top growth reduced at 28.6 dS m−1; FSP‐2 and ‘Futurf’ were intermediate in salt tolerance with 50% top growth reductions at 21.9 dS m−1; whereas ‘Adalayd’ (‘Excaliber’) was the most sensitive cultivar with 50% top growth reduction at 18.4 dS m−1. The FSP‐1 selection was 3.1 times more salt tolerant than the other grasses when top growth was reduced only 5% at low salt concentrations. Salinity differentially affected tissue content of Ca, C1, K, Mg, and Na between grasses but had no affect on N which averaged 37.3 g kg−1. Maximum tissue content of 22.3 g kg−1 of CI and 16.4 g kg−1 of Na were at a salt concentration of 31 dS m−1 in FSP‐1. However, concentrations of Cl and Na in the other grasses increased linearly 0.4 and 0.5 g kg−1, respectively, with each increase in salinity concentration. Maximum accumulation in this group was at the highest salt treatment of 39.7 dS m−1 where Cl varied between grasses from 24 to 31 g kg−1 and Na varied from 20 to 24 g kg1. Tissue content of Ca, K, and Mg decreased with increased salinity and differed between grasses. No mortality was observed although top growth of all grasses was severely reduced at the highest salt level.
Uptake, Distribution, and Remobilization of 15N‐labeled Urea Applied to Maize Canopies1
Authors: Below F. E. , Crafts‐Brandner S. J. , Harper J. E. , Hageman R. H. 
Published: July 2010

AbstractField‐grown maize (Zea mays L.) plants (hybrid B73 X Mo17) were sprayed with 15N‐enriched urea to determine recovery and subsequent distribution within the plant. Plants were sprayed with 15N enriched urea at 7 days pre‐ (treatment 1) and post‐anthesis (treatment 2) to provide a total of 22.3 kg N ha−1 (350 mg N plant−1). Unsprayed plants were used as controls. Plots were located on Flannigan silt loam (fine, montmorillontic mesic Aquic Argiudoll) at stands equivalent to 63 800 plants ha−1. Timing of spray treatment had no effect on grain yield, stover weight, visible leaf senescence, or N content of the plant parts, relative to controls. About one‐third (29% in treatment 1, 30% in treatment 2) of the foliarly applied urea was absorbed and incorporated by the plant. The amounts and distribution patterns within plant parts of foliarly applied N and of total N (N derived from soil uptake and foliarly applied urea N) indicated that leaves were the organs of uptake, and that the stalk served as a conduit for passage of urea‐derived N from leaves to the ear rather than as a storage organ for foliarly applied N. The greater initial rates of loss and the final extent of depletion of N from leaves was greater for foliarly applied N than for total N. This indicated that the foliarly applied N was incorporated into a different pool of N than had been formed earlier by unenriched soil derived N. This observation provides possible explanation for the failure of foliar N applications to increase grain yields of maize.
Fall Cutting of Alfalfa in the North Central USA1
Authors: Tesar M. B. , Yager James L. 
Published: July 2010

AbstractThe North Central (NC) and Northeast (NE) states produce almost two‐thirds of the alfalfa (Medicago sativaL.) in the USA. Three cuttings by early September is the most popular management system. A third cutting in mid‐September to early October has been considered deleterious to subsequent yield and persistence compared with cutting in late August or early September. Our objective was to determine the effects of the final cutting date on subsequent yields and persistence of fertilized and unfertilized hardy and moderately hardy cultivars in a three‐cut system in southern Michigan. Hardy (‘Vernal’ and ‘Cayuga’) and moderately hardy (‘DuPuits’, ‘Saranac’, and ‘Honeoye’) alfalfa cultivars were used in four separate experiments on well‐drained Conover loam (fine‐loamy, mixed mesic Udollic Ochraqualfs). Third cuttings made on 15 September or 1 or 15 October for three consecutive years did not reduce the subsequent year's yield or persistence compared with the control cutting date of 1 September if the cultivar was resistant to bacterial wilt [Corynebacterium insidiosum(McCull) H.L. Jens] and fertilized with K. Yields were reduced if the cultivar was wilt‐susceptible and was cut on 15 September. Levels of total available carbohydrates (TAC) followed similar bi‐monthly trends between 6 September and 13 December for both cultivars. Average TAC content of the two cultivars increased to 304 g kg−1on 1 November and then decreased to 271 g kg−1on 13 December when alfalfa was dormant. On 13 December, levels of TAC were the same within cultivars for all fall cutting treatments and lower for DuPuits than for Vernal. Yields and persistence were not reduced by variable dates of fall cutting after a second cutting in mid‐July if the cultivar was wilt‐resistant, hardy or moderately hardy, and the soil had been well fertilized with K. The present recommendation of not cutting in September and early October or 4 to 6 weeks before the first killing frost in the NC and NE states should be reevaluated.
Resistance of Plant Roots to Water Loss1
Authors: Baker J. M. , van Bavel C. H. M. 
Published: July 2010

AbstractIn an attempt to resolve questions about the relative magnitudes of root resistance to uptake and exudation, an experiment was conducted in which the root zone of a bermudagrass (Cynodon dactylon ✕ Cynodon transvaalensis L. Pers.) sod was divided by a barrier in such a manner that water could move from one side to the other only through the lateral stems of the connected plants. A large difference in soil water potential between the two sides was created by watering one side only. Under such circumstances nocturnal transfer of significant amounts of water from one side to the other, through the plant system, was observed repeatedly with a gamma probe. A separately measured resistance to uptake allowed calculations of the exudation resistance, which was found to be 1.2 ✕ 107 MPa s−1 m−1, slightly larger, but of the same magnitude as the resistance to uptake. It was concluded that water will move from root to soil if the potential gradient is in that direction, though other factors such as soil hydraulic conductivity may become limiting.
Cotton Fruiting Modification with Mepiquat Chloride1
Authors: Kerby T. A. , Hake Kater , Keeley Mark 
Published: July 2010

AbstractFruiting of cotton (Gossypium hirsutum L.) was evaluated by main stem node and branch position in 11 experiments over a 4‐yr period to determine if mepiquat chloride (MC) (1,1‐dimethylpiperidinium chloride) altered fruiting position development or retention. Fruiting events were monitored for main stem nodes 7 to 20 for first fruiting position on sympodial branches (SB1), secondary fruiting positions on sympodial branches (SB>1), and fruiting positions on monopodial branches (MB). Ten consecutive plants were plant mapped from each of four replications in each experiment and combined as a 40‐plant total for analysis of treatment and node effects using experiments as replications. Mepiquat chloride was applied at 49 g ha−1 when average plant height was 0.57 m and plants averaged 0.9 white blooms m−2. Summed across nodes, plant zones SB1, SB>1, and MB accounted for 60, 26, and 13% of all harvestable bolls, produced 37, 46, and 17% of all fruiting positions, and set 45, 16, and 23% of all fruiting positions as harvestable bolls, respectively. Application of MC did not increase total number of bolls. The interaction of MC treatment and nodes was significant for SB1 and SB>1, with MC treated plants setting more bolls at lower nodes but fewer at upper nodes. The maximum cumulative benefit occurred at node 12 where MC treated plants had 15% more bolls matured than control plants (58.3 and 50.6 bolls m−2, respectively). This advantage from MC treatment was not maintained as upper nodes matured fewer bolls than control plants. Plants treated with MC produced 3.1% fewer (P = 0.07) fruiting positions than control plants (288 and 279 m−2 respectively). Treatment by node interactions were significant for SB1 and SB>1, with MC increasing fruiting positions up to node 15 at SB1 and up to node 9 for SB>1, but having fewer at the remaining nodes. Early boll load was stimulated by MC. Late season boll load was decreased, apparently not by limited initiation of fruiting positions, but rather by increased abortion of fruiting forms. Use of MC according to the rate and timing of these tests would be of benefit when length of the season is a primary constraint to yield potential. In full‐season, non‐rank cotton, however, the early benefit in boll load is lost.