bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of Solid‐Seeded Soybeans to Flood Irrigation. I. Application Timing1
Authors: Griffin J. L. , Taylor R. W. , Habetz R. J. , Regan R. P.
Published: July 2010

Variation in seasonal rainfall accumulation directly affects soybean [Glycine max(L.) Merr.] yields. In southwest Louisiana, where soybeans are primarily grown in rotation with rice (Oryza sativaL.), moisture shortages frequently occur due to the presence of a traffic‐induced hardpan 15 to 20 cm below the soil surface, which restricts root development. Field studies were conducted in southwest Louisiana on a Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf) soil during 1981–1983 to study response of solid‐seeded ‘Dare’ (Maturity Group V) and ‘Ransom’ (Maturity Group VII) soybeans to flood irrigation. Water was applied at R2 bloom (B), R5– R6 pod fill (PF), B + PF, and full season (FS) as needed based on tensiometer readings (60 to 65 cbar). A nonirrigated control was included for comparison. In 1981 rainfall was adequate prior to bloom, but deficient when plants entered the reproductive stage. In 1982 and 1983, rainfall was generally deficient prior to bloom but adequate during the reproductive stage. Yield responses to the irrigation treatments varied among years and were directly related to rainfall distribution. Averaged over years, Dare yields were 161 kg ha−1higher (P=0.05) than the control where water was applied at B + PF and Ransom yields were 168 and 323 kg ha−1higher (P=0.05) than the control where water was applied at B + PF and FS, respectively. Seed/pod for Ransom and 100‐seed weight for Ransom and Dare averaged over years were significantly higher than the control only where water was applied FS. Pods/plant, seed/plant, plant height at maturity, lower pod height, and plant density were not affected by the irrigation treatments. Results indicate that in years where moisture is limited prior to bloom, early application of water can be beneficial, provided it is applied as needed throughout the remainder of the growing season. In years where moisture is adequate in early season prior to bloom, water should be applied during the reproductive stage if water shortage occurs.
Dry Matter Accumulation and Seed Yield of Determinate and Indeterminate Soybeans1
Authors: Beaver J. S. , Cooper R. L. , Martin R. J
Published: July 2010

Some determinate soybean [Glycine max(L.) Merr.] cultivars developed for the northern USA yield as well as the conventional indeterminate cultivars. The principal objective of this research was to compare morphological and physiological traits of the determinate cultivar ‘Elf’ with the indeterminate cultivar ‘Williams’ and a determinate isoline of the cultivar ‘Clark.’ Field experiments were conducted at Urbana, IL in 1976 on a Flanagan silt loam (fine, montmorillonitic, mesic Acquic Argiudoll) and at Wooster, OH in 1981on a Wooster silt loam (fine‐loamy, mixed, mesic Typic Fragiudolf). Plants from weekly samples taken from the 5th week after emergence until R7 were separated into leaflets, petioles, main stems, branches, pods from main stems, and pods from branches. Patterns of dry weight accumulation for the plant parts were estimated using regression techniques. Estimates of seed yield components were obtained from an adjacent set of experiments. The genotypes accumulated leaf, petiole, and total dry weight in a similar fashion. Williams accumulated more main stem dry weight than the determinate genotypes. However, the difference in main stem dry weight was partially compensated by a greater branch dry weight of the determinate genotypes. Although Williams produced more main stem nodes, the determinate genotypes set as many pods on the main stems as Williams. The determinate genotypes produced a greater number of pods and more seed weight from branches than Williams. In 1976, Elf accumulated reproductive dry weight at a greater rate than Williams or Clark (dt1). The apparent harvest index of Elf was greater than the other genotypes during both years. Seed yields did not differ in 1976, whereas the determinate genotypes yielded slightly less than Williams in 1981.
Response to Soil Temperature of Dinitrogen Fixation (Acetylene Reduction) Rates by Field‐Grown Soybeans1
Authors: Sinclair T. R. , Weisz P. R.
Published: July 2010

Temperature has a major effect on the dinitrogen (N2) fixation rate of legume nodules. Experiments were performed under field conditions to assess the influence of soil temperature on acetylene reduction rates by soybean [Glycine max(L.) Merr.]. Data were collected in situ under low acetylene concentrations such that observations of a number of plants were made every 30 min throughout diurnal periods. Significant positive correlations existed between acetylene reduction rates and soil temperature at temperatures below 30 °C. A linear model and an exponential model fit the data equally well over the 10 to 12 °C ranges where data were obtained. Since it was determined that both the nodule gas conductance and maximum activity of the nodule changed in parallel, it was not possible to identify which of these terms was responding directly to the changes in soil temperature. Between 30 and 33 °C little change in acetylene reduction rates with soil temperature was observed. Above 34 °C declines in acetylene reduction rates were observed. The decline was usually to 70% of the values observed in the 30 to 33 °C soil temperature range. Little or no recovery was observed in acetylene reduction rates after this high‐temperature–induced decline, indicating that a more permanent alteration had occurred in the nodules.
Distribution of Small Grain Residue Produced by Combines1
Authors: Allmaras R. R. , Douglas C. L. , Rasmussen P. E. , Baarstad L. L.
Published: July 2010

A uniform distribution of small grain residues is needed in conservation tillage systems, but measurements are needed to describe the degree of uniformity or nonuniformity actually produced by combines. A combination of hand‐cut bundles of wheat (Triticum aestivumL.) plus straw before a combine pass; straw plus chaff deposit on a canvas apron and hand‐cut bundles of the uncut stubble were used to measure the distribution of small grain residue produced by 12 test combines. Header width varied from 5.5 to 7.3 m, grain production from 4.8 to 7.1 Mg/ha, and straw (plus chaff) production from 9.0 to 11.4 Mg/ha. From 52 to 64% of the straw plus chaff was threshed. An uneven residue distribution ratio (URDR) of maximum total to minimum total residue varied from 1.4 to 5.1 depending on combine and residue distribution system. A dispersion index (DI), which ranges from 0 for an even distribution to approximately 0.5 for a severely uneven distribution, varied from 0.09 to 0.42. All test combines with a standard flail spreader gave DI > 0.23. Dispersion indexes ≤ 0.14 were produced by a retrofit chaff spreader on a cylinder‐type combine, a farm‐shop modified flail spreader system on a rotary‐type combine, and an experimental straw chopper on a rotary combine. Agronomic and machinery operation problems associated with chaff rows suggest an URDR < 1.5 is needed to successfully manage no‐till after small grain harvest. A DI < 0.1 can be attained without excessive costs to improve spreading devices.
Organic Matter Relationship to Soil Nutrient Status and Aluminum Toxicity in Alfalfa1
Authors: Kapland D. I. , Estes G. O.
Published: July 2010

The objective of this investigation was to evaluate in unaltered soils the relationship of organic matter (OM) to soil nutrient levels and aluminum (Al) toxicity to alfalfa. The Apand B21horizons from 12 agricultural soils were collected from throughout New Hampshire. The pH range of the soils was 4.91 to 6.60, exchangeable Al was 0.01 to 0.89 cmol (p+) kg−1, organic matter was 6.6 to 81.6 g/kg, and textures ranged from sandy to silt loams. Four kilograms of each soil were potted and seeded to alfalfa (Medicago sativaL.) in a greenhouse experiment. The level of soil OM was highly correlated with top dry weights of 3‐week old alfalfa and top and root dry weights of 9‐week old alfalfa. Increases in OM levels also resulted in corresponding increases in exchangeable soil calcium, magnesium, potassium, extractable phosphorus (Bray 1), total nitrogen, and cation exchange capacity (CEC). A significant amount of variation in the top dry weights of 3‐week old plants and in the top and root dryweights of 9‐week old plants was accounted for by taking into consideration the interaction of Al and organic matter. With the use of three‐dimensional computer plotting programs, the critical Al level of alfalfa was correlated with soil OM levels (r=0.883). An incremental increase of 1% in soil OM on a dry‐weight basis (starting from about zero) increased critical Al levels by 0.3 cmol (p+) kg−1
Dry Matter Partitioning as Influenced by Competition Between Soybean Isolines1
Authors: Wilcox J. R.
Published: July 2010

Intergenotypic competition has been shown to bias estimates of seed yield among soybean [Glycine max(L.) Merr.] genotypes. It is unknown how early in plant development intergenotypic competitive effects occur and what plant parts are affected. The objectives of this research were to determine what plant characteristics were affected by intergenotypic competition and how early in plant development these effects could be detected. Two soybean isolines ‘Clark’ and ‘Clark‐e2’, which matures 14 days earlier than Clark, were grown in hill plots at two spacings, 0.38 and 0.76 m between hills in 1981 and 1982. Plots were grown at Lafayette, IN on a Chalmers soil (finesilty, mixed, mesic Typic Haplaquoll). Three areas of hills were planted, (i) all hills of Clark, (ii) all hills of Clark‐e2, and (iii) alternate hills of Clark and Clark‐e2. At the fourth trifoliolate stage and at 2‐week intervals thereafter, three adjacent hills of Clark, of Clark‐e2, and three hills of each isoline in the area planted to alternate hills were harvested. Dry weight of stems, leaves, and pods plus seeds were recorded. Results were similar for the two spacings. Stem weight of Clark was significantly greater when bordered by Clark‐e2than when self‐bordered from the time of initial seed development through maturity. Stem weight of Clark‐e2was unaffected by the phenotype of surrounding plants. Leaf weight of Clark was significantly greater when bordered by Clark‐e2than when self‐bordered from the time of initial seed development until leaves began to yellow and drop. Like stem weight, leaf weight of Clark‐e2was unaffected by the phenotype of the surrounding hills. Competitive effects for pod weight (including seeds) were apparent throughout pod and seed development to maturity. Pod weight of Clark was enhanced and of Clark‐e2was depressed when the two genotypes were grown in alternate hills.
A Weighing Lysimeter for Evapotranspiration and Root Measurements1
Authors: Dugas William A. , Upchurch Dan R. , Ritchie Joe T.
Published: July 2010

Crop water use is intimately tied to soil water and rooting patterns. Therefore, a lysimeter was fabricated which is unique in that root density and water content measurements can be made throughout an undisturbed soil profile coincident with whole‐profile evapotranspiration measurements. With this lysimeter, interrelationships throughout this soil profile between rooting depth and density, soil water content, plant water uptake, and evaporative demand can be evaluated. The lysimeter was constructed with a steel outer and inner box. The inner box contained an undisturbed soil monolith and was set on a scale, which in turn was set on the outer box floor. The 2.0 by 1.5 by 2.54 m monolith was obtained by forcing a steel box over a soil pedestal. Root growth and density and soil water are capable of being monitored throughout the monolith by using 36 clear, extruded acrylic tubes that were inserted horizontally through the monolith at various depths. Most of the soil mass is counterbalanced and the system is capable of resolving water mass changes equivalent to 0.02 mm. Evapotranspiration rates determined from the lysimeter compare favorably with empirical estimates. Costs for the facility and manpower requirements for operations and maintenance are substantial. However, root and soil water measurements, which are possible with this lysimeter, in conjunction with total‐profile water loss measurements, provide a means for quantitatively evaluating interrelationships throughout the profile between these important phenomena.
Pre‐Anthesis Defoliation Effects on Six Corn Inbreds1
Authors: Vasilas B. L. , Seif R. D.
Published: July 2010

Yield loss due to defoliation prediction charts have been developed for corn (Zea maysL.) hybrids, but not for inbreds. The latter is needed by the hail‐loss insurance industry. Field experiments were conducted at the University of Illinois on a Drummer silty clay loam (Typic Haplaquoll) in 1982 and a Flanagan silt loam (Aquic Argiudoll) in 1983 to evaluate the response of six corn (Zea mays L.) inbreds to 0, 50, and 100% defoliation at the 14‐leaf stage with respect to grain yields and yield components. One inbred, FRMo17rhm, produced yield responses quite different from the other five. Complete and 50% defoliation reduced grain yields of five inbreds by an average of 45.5 and 2.5%, respectively; and FRMol7rhmby 86.0 and 17.0%, respectively. With the exception of FRMo17rhm, yield, decreases were due more to a reduction in kernel number than kernel size. Yield reductions with 50% defoliation were due to a reduction in ear number as opposed to kernels per ear; whereas complete defoliation affected both yield components. Ear number was reduced both by decreasing the number of plants with double ears and increasing the number of barren plants. In general, genotypic differences in the yield response to complete defoliation coincide with genotypic differences in final leaf number and the effect of defoliation on increasing the interval between anthesis and silking.
Performance of Switchgrass and Bluestem Cultivars Mixed with Cool‐Season Species1
Authors: Jung G. A. , Griffin J. L. , Kocher R. E. , Shaffer J. A. , Gross C. F.
Published: July 2010

Forage availability in summer is critical for sustaining high stocking densities of herbivores on pasture in the eastern U.S. The objective of this study was to determine forage productivity and quality of switchgrass (Panicum virgarumL.) and bluestems [Andropogon gerardiiVitman, Schizachyrium scoparium(Michx.) Nash, and Bothriochloa caucasica(Trin.) C.E. Hubb.] in summer. The experimental site was located in southwestern Pennsylvania on Guernsey silt loam (fine, mixed, mesic Aquic Hapludalf) soil. Two replicates, each containing eight warm‐season grasses with different proportions of volunteer cool‐season grasses and overseeded legumes were grazed from 1975 to 1977 and then harvested for hay in 1978 and 1979. Pastures were grazed each year in mid‐May, late July or early August, and early October. Nitrogen at 0, 45, and 90 kg ha−1and P at 0, 20,40 kg ha−1were applied to subplots. ‘Blackwell’ switchgrass and ‘Kaw’ big bluestem from the Great Plains readily established stands but did not persist as well as cultivars from the eastern USA. Total annual production from switchgrass‐dominated pastures was about 8.0 Mg ha−1and that from ‘NY 1145’ big bluestem was 6.0 Mg ha−1, Over a 4‐yr period, NY 1145 produced about 70% more forage in late July than did Kaw big bluestem. Mean yield distribution of the switchgrass and bluestem pastures was approximately 15% in May, 55% in July‐August, and 30% in October. July yield increased about 11 kg kg−1of N applied. Mean in vitro dry matter disappearance (IVDMD) values for switchgrass and bluestem ranged from 470 to 570 g kg−1,, but it was determined that IVDMD under‐estimated in vivo digestibility by 100 to 200 g kg −1, Crude protein concentration ranged from 70 to 120 g kg−1, Mean crude protein concentration of grass fertilized with 45 and 90 kg N ha−1over a 3‐yr period was 10 and 26% higher, respectively, than that for unfertilized grass. Overseeded legumes, especially red clover (Trifolium pratenseL.), established good stands in warm‐season grasses with < 75% stands. Mixed stands of warm‐ and cool‐season grasses and legumes can be maintained under grazing or hay production, with a substantial shift in seasonal yield distribution that can be very beneficial to beef (Bos taurus) producers.
Electronic Detection of Bolus Swallowing to Measure Forage Intake of Grazing Livestock1
Authors: Forwood J. R. , Hulse M. M. , Ortbals J. L.
Published: July 2010

Understanding forage intake of grazing livestock is critical to understanding their level of performance. Unfortunately, current methods of measuring intake of free‐roaming ruminants are laborious and indirect. To overcome these problems, two devices were tested with confined animals to measure passage of boli within the esophagus of cattle (Bos taurus) as an estimate of intake. The first, labeled a conductivity transducing cannula (CTC), consisted of electrodes mounted slightly above the sleeve on a conventional metal sleevetype esophageal cannula so they would contact material passing within the esophagus. A stable current source allowed data to be transmitted to a strip chart recorder via coaxial cable. The second device, a pressure transducing cannula (PTC), involved a flexible water‐filled tube mounted on the conventional cannula sleeve. Material passing within the esophagus exerted pressure on the tube. A pressure transducer converted water pressure to an electrical signal which was received by a strip chart recorder. The PTC device was discarded for lack of accuracy and portability. The CTC device was modified and inserted in year‐old esophageally fistulated steers fed known amounts of forage in confinement. The cannula accurately signaled forage swallowing events. The CTC device appears to distinguish boli swallowing from eructation and water swallowing. The CTC device also shows a positive relationship between number of swallows and dry matter intake of differing levels of orchardgrass hay (r2= 0.81) and chopped big bluestem grass (r2= 0.99).
Modeling of PAR Interception and Productivity of a Prickly Pear Cactus, Opuntia ficus‐indicaL., at Various Spacings1
Authors: de Cortázar Victor García , Nobel Park S.
Published: July 2010

Opuntia ficus‐indicuL. is a prickly pear cactus composed morphologically of flattened stems (cladodes). It is cultivated worldwide for fruit or forage, generally in plantations at low plant densities. A model developed for simulating light interception by each cladode at any plant density was used to simulate the effect of plant morphology on production of dry matter. Different plant structures and cladode orientations leading to high stem area indices (SAI; total surface area of stems per unit ground area) were tested to maximize Productivity, while maintaining the crop within limits of size and spacing compatible with practical management techniques. Results indicate that productivities 40% greater than those observed in the field and similar to certain other row crops can be obtained by increasing SAI up to 4.0 for plants that are five cladodes tall. for much greater SAIs, crops become very dense with no significant increase in productivity. For whole plants at low SAIs and for top cladodes at all SAIs, higher productivity occurred for cladodes facing east‐west. However, at high plant densities row direction and orientation of individual cladodes had little effect on productivity, although plants with their cladodes facing north‐south tended to have a higher productivity. The simulations presented can aid in the design of field trials for productivity studies of O. ficus‐indicaand other cultivated platyopuntias.
Ergot Toxicity from Endophyte‐Infected Grasses: A Review1
Authors: Bacon Charles W. , Lyons Philip C. , Porter James K. , Robbins Joe D.
Published: July 2010

Clarifying the role of grasses parasitized by a tribe of clavicipitaceous endophytes (Balansiae) in the etiology of the many cattle (Bos taurus) ergot toxicity syndromes is essential for identifying the correct toxic grass and establishing the proper pasture management practice necessary to eliminate toxicity. The distinction is required as the management practice used to prevent ergot toxicity by Clavicepsdoes not apply because of the systemic habit of the Balansiae. Research is reviewed, which established that endophytic parasites of many genera of warm‐season perennial weed grasses and tall fescue (Festuca arundinaceaSchreb.) are producers of toxic ergot alkaloids. This group of fungi is distinct from the closely related genus Clavicepsin being an intercellular parasite of leaf tissue. These fungi are parastic on nine tribes of grasses that have a wide geographic distribution in the western hemisphere. Nine ergot alkaloids belonging to the clavine group have been isolated from four species of Balansiacultured in laboratory media, and several of these have been isolated from parasitized grasses. Ergot alkaloid production by the remaining nine species of Balansiahas not been examined. The endophyte of tall fescue produced both the clavine and ergotamine peptide groups of alkaloids in culture and in the grass. The production of ergot alkaloids by weed grass endophytes is host‐related; therefore, each parasitized weed grass must be assessed for alkaloid production. All isolates of B. epichloe(Weese) Diehl from smutgrass (Sporobolus poiretiiRoem. and Schult.) and 54% of the isolates of B. henningsiana(Moell.) Diehl from broomsedge (Andropogon virginicusL.) produced the following alkaloids in culture: chanoclavine, ergonovine, ergonovinine, and agroclavine. Isolates of these two fungi from other grass genera did not produce alkaloids. While no extensive survey has been done to date, all infected tall fescue examined contains ergot alkaloids. The main peptide alkaloid produced by the tall fescue endophyte is ergovaline. The effects of this peptide alkaloid on cattle have not been determined. However, the total alkaloids produced in culture by B. epichloereduced the serum prolactin levels in cattle and along with prior published accounts on the physiological effects of the clavine and peptide ergot alkaloids, established that these alkaloids can cause toxicity symptoms in cattle consuming infected plant material. Thus, pasture management practices must include procedures that will prevent the growth of grasses that serve as host for endophytic fungi.
Quality and Yield Response of Four Warm‐Season Lawngrasses to Shade Conditions1
Authors: Barrios E. P. , Sundstrom F. J. , Babcock D. , Leger L.
Published: July 2010

Warm‐season turfgrasses differ widely in their tolerance to low light. Shade conditions, as the result of shrub or tree presence, are greatly influenced depending on whether the tree or shrub is deciduous or evergreen in nature. The purpose of this study was to determine the influence of deciduous shade on the quality and yield of four major warm season lawngrasses. Zoysiagrass [Zoysia japonica(Stued.) ✕ Z. tenuifolia(Willd.) ‘Emerald’], St. Augustinegrass [Stenotaphrum secundatum(Walt.) Kuntze] ‘Floratam’ and ‘Floratine’, and centipedegrass [Eremochloa ophiuroides(Munro.) (Hack.) ‘Oklawn’] were sodded in outdoor plots on an Olivier silt loam (fine‐silty, mixed, thermic aquic, Fragiudalf) soil. All were exposed to unshaded and 47 and 63% shade regimes of green saran screening for 7 months each year to simulate Gulf South deciduous shade tree conditions. Determination of lawngrass quality and yield responses were made for 3 yr. Increased shade decreased air temperature at sod level. Mean air temperature at sod level was not correlated with quality of any lawngrass. Mean air temperature at sod level was significantly correlated only with clipping yields of Floratam St. Augustinegrass and Oklawn centipedegrass. Lawngrass quality generally decreased with increasing shade. Photon flux density was significantly correlated with quality of all lawngrasses except Oklawn. Quality ratings in 63% shade indicate that Floratam St. Augustinegrass quality was most intolerant, while Oklawn centipedegrass quality was most tolerant of reduced light conditions. Quality and yield were not significantly correlated in any lawngrass. Lawngrass yield generally decreased with increasing shade. Emerald Zoysiagrass mean clipping yields were least reduced, and Floratam St. Augustinegrass mean yields were most reduced in 63% shade treatments.
Copper Deficiency in Cereal and Oilseed Crops in Northern Canadian Prairie Soils1
Authors: Karamanos R. E. , Kruger G. A. , Stewart J. W. B.
Published: July 2010

Transitional grassland/forest light soils in Saskatchewan are often deficient in Cu. The high cost of micronutrient fertilizers necessitates extreme care in identifying micronutrient deficiencies and selecting effective products and methods of application. Comparison of tissue and grain or seed analysis for spring wheat (Triticum aestivumL.), canola (Brassica napusL.), and flax (Linum usitatissimumL.) vs. DTPA‐extractable soil Cu levels revealed that diagnosis of Cu deficiencies can more accurately be achieved via the latter. The critical DTPA‐extractable Cu levels were 0.40 mg Cu kg−1of soil for spring wheat and 0.35 mg Cu kg−1of soil for canola and flax. A series of field experiments comparing different forms of soil and foliar Cu fertilizers were conducted on several transitional grassland/forest soils. Copper oxide applied in the spring was generally ineffective in the year of application but alleviated Cu deficiencies in the following year. Copper‐sulfate (blue stone) and chelated products (polylignosulphonic acid) were effective in the year of application. However, the latter had no residual value at the rates of application used. This, combined with their extremely high current prices, makes them an undesirable Cu fertilizer source for the soils in the study area. Foliar Cu applications of either Cu‐sulfate or Cu‐chelate may be effective, but their performance has been erratic; hence, they should only be considered as an emergency measure for correcting of Cu deficiency.
Planting Date and Foliar Fertilization of Corn Grown for Silage and Grain under Limited Moisture1
Authors: Giskin M. , Efron Y.
Published: July 2010

Crop production costs have increased in recent years, which has caused a search for more economical cultural practices. In view of this, field experiments were carried out in 2 successive years to study the effect of seeding date and foliar fertilization on grain and silage yields of corn (Zea maysL.). The plantings ranged from 15 February to 1 April. The soil was a silty clay loam (Typic Chromoxerert). The crop was given supplemental irrigation only and received one or two foliar applications of N,P,K, and S, applied at the four‐ or five‐leaf stage. In the first year silage and grain yields decreased with each delay in planting date. The foliar application of N,P,K, and S resulted in a significant uptake on N and P, but not of K, with the increase in plant‐N being a function of seeding date. Foliar fertilization resulted in a significant 16.6% increase in grain yield, but no addition to silage yield. In the second year either one or two foliar applications of essential nutrients significantly increased silage and grain yields. Two foliar applications were significantly more effective than one application in increasing silage yield, but not grain yield. In both years yields of the February and March plantings were affected by low soil and air temperatures during the seedling stage; the yields of the April seeding were affected by a shortage of moisture from silking through grain fill. Planting early was critical for obtaining maximum benefits from foliar fertilization when applied at the four‐ or five‐leaf stage. Foliar application of N,P,K, and S resulted in yield increases of both silage and grain if moisture was not limiting from silking to physiological maturity.
Effect of High Sulfate Irrigation Waters on Soil Salinity and Yields1
Authors: Papadopoulos I.
Published: July 2010

More information is needed concerning the effects of high sulfate waters on soil salinization and the magnitude of yield losses of crops irrigated with such waters. This greenhouse study investigated the response of tomato (Lycopersicon esculentumL.), eggplant (Solanum melongenaL.), and bell pepper (Capsicum annuumL.) to soil salinity as influenced by the ionic composition of two naturally occurring sulfate waters (EC=3.1 dS/m) in comparison to rainwater. One of the saline waters was saturated with gypsum (34.8 mmol(−)/L) and the other contained 15, 18, and 14 mmol(±)/L of SO24, Na, and Cl, respectively (mixed water). In all treatments a 0.3 leaching fraction was used. The soil was a Pellic Vertisol, which contained no gypsum. Soil salt buildup was high with the saline waters and followed two stages. A sharp increase of soil electrical conductivity (EC) initially occurred with ions of both sparingly (Ca, SO24) and highly (Mg, Na, Cl) soluble salts contributing to soil EC. Sulfate concentration at the initial stage increased due to the presence of other ions in the soil solution and it was more than twice that of a pure gypsum solution. At the second stage, Ca and SO24concentrations in soil solutions remained unchanged and the increase of EC was slower in comparison with the initial stage. At both stages the increase of soil EC was higher with the mixed water. A significant increase of soil solution sodium adsorption ratio (SAR) also occurred with the mixed water. Fresh fruit yields of tomato decreased by 29 and 21%, and eggplant yields were reduced by 23 and 16% when irrigated with the mixed or the sulfate water in comparison to rainwater, respectively. Lower yield was due to smaller fruit size. Yield of bell pepper was not affected, but quality deteriorated.
Weed Seed Decline and Buildup in Soils Under Various Corn Management Systems Across Nebraska1
Authors: Burnside Orvin C. , Wilson Robert G. , Wicks Gail A. , Roeth Fred W. , Moomaw Russell S.
Published: July 2010

The weed seedbank in the soil makes weed control necessary every year in crop production. Research was initiated to determine if a farmer could reduce weed control practices after several years of excellent weed control. Experiments were conducted at five locations across Nebraska to determine the demise of weed seed in continuous corn (Zea maysL.) where weed seed production had been eliminated for 3 yr (1975–1977) and then four weed management levels were superimposed for another 3 yr (1978–1980). Soils were Cumulic Haplaquolls, Typic Argiudolls, Udic Agriustolls, Typic Haplustolls, and Aridic Haplustolls. Within 1 yr (1978) after weed eradication had stopped, the average number of weed seeds that germinated increased over the four weed management levels; and weed competition to corn was evident within 2 yr (1979). Weeds have the potential to rapidly increase and reinfest a field once there is a lack of vigilance in the weed control program. Thus, the weed seedbank assures a continuity to the weed problem that will require more than eliminating weed seed production for several years. If a farmer has achieved 3 yr of perfect weed control on a given field, he still must expect weed problems in subsequent crops because of seed longevity in soil.
Effects of Carbon Dioxide Enrichment and Soil Water on Maize1
Authors: King K. M. , Greer D. H.
Published: July 2010

The current global rise in atmospheric CO2concentration may lead to changes in yield and water use of crops. This study was done to determine the effects of increased CO2in combination with soil water levels on the growth, yield, transpiration, and water use efficiency of maize (Zea mays L.). Corn plants (cv. PX74) were grown in Opiki humic silty clay loam (fine, illitic, mesic Histic Humaquepts) soil in 22‐L pots from emergence to maturity (111 days) in controlled‐environment rooms at CO2concentrations of 350/360,600/ 650, and 850/900 µL L−1(day/night). Within each room, at a given CO2 concentration, the plants were subjected to one of three soil water treatments: complete replacement of weekly transpiration (control) and 75 and 50% replacement of the control transpiration. The 350 µL L−1treated plants produced an average of 401 g dry matter across all water treatments and the 600 and 850 µL L−1treated plants produced an average of 431 and 436 g dry matter per plant, respectively. The differences in total dry matter between the 600 and 850 µL L−1treated plants remained nonsignificant throughout the experiment. There were significant differences between all soil water treatments in dry matter production with the low soil water level averaging 284 g and the medium and high water level averaging 440 and 544 g plant−1, respectively. Transpiration was reduced with increased CO2concentration and was 80.5 and 70.4% at 600 and 850 µL L−1, respectively, of that at 350 µL L−1averaged across water treatments. The water use efficiency (WUE) increased markedly with increased CO2concentration. At 600 and 850 µL L−1the WUE was 34 and 55% greater, respectively, than at 350 µL L−1. Further work is needed on the applicability of this controlled environment experiment to the real world.
Effect of Tillage Systems on Proso Millet Production1
Authors: Anderson R. L. , Shanahan J. F. , Greb B. W.
Published: July 2010

Proso millet (Panicum miliaceum L.) is well‐adapted for the Central Great Plains and could be planted in a winter wheat (Triticum aestivum L.)–millet‐fallow rotation, resulting in two crops in 3 yr. To determine the most suitable tillage system for proso millet production within this rotation, seven tillage management systems were evaluated over a 6‐yr period (1972–1977). The research was conducted on a mesic Pachic Arguistill soil on the Central Great Plains Research Station near Akron, CO. Comparisons included fall vs. spring tillage and replacing a tillage operation with herbicides. Controlling fall weed growth by tillage alone or with atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐S‐triazine) increased grain yield of proso millet and protein content of the grain more than spring tillage for weed control. Increased millet production from fall tillage was attributed to increased soil NO−3‐N levels and increased soil water use by millet. Water use efficiency by millet was also increased with fall tillage. Adding N fertilizer decreased millet grain production.
A Comparison of Sprinkler and Flood Irrigation for Rice1
Authors: Westcott M. P. , Vines K. W.
Published: July 2010

Sprinkler irrigation of rice (Oryza sativa L.) has recently been considered to reduce water use and increase grower flexibility in U.S. production areas where flood irrigation is predominant. Tests were conducted for 2 yr on a Sharkey clay (Vertic Haplaquept) to evaluate selected rice cultivars under sprinkler vs. flood irrigation. Irrigation methods were main plots and three cultivars in 1983 and six cultivars in 1984 were subplots. Sub‐subplots in 1984 were single or split application of 101 kg N ha−1. Sprinkler irrigation consisted of three weekly applications of 0.038 m water each in 1983 and a similar scheduling to maintain soil moisture tension above –30 kPa in 1984. In 1983, sprinkler irrigation increased sheath blight (Rhizoctonia solani) incidence and decreased grain yield (4448 kg ha−1 vs. 7139 kg ha−1 under flood irrigation), dry matter production, harvest index, and florets per panicle compared to flood irrigation. In 1984, despite chemical control of sheath blight, yields averaged 5901 kg ha−1 under sprinkler irrigation vs. 7846 kg ha−1 under flood irrigation. Nitrogen timing did not significantly affect yields, but a weak N timing ✕ irrigation method interaction (p=0.061) denoted that split N applications may benefit yields under sprinkler irrigation. multiple regression indicated fewer florets per panicle was the primary source of yield loss with sprinkler irrigation. Sprinkler irrigation of rice might decrease water use but it lowers yields and increases need for fungicides compared with flood irrigation.
Nitrogen‐15‐Determined Nitrogen Fixation in Field‐Grown Chickpea, Lentil, Fababean, and Field Pea1
Authors: Rennie R. J. , Dubetz S.
Published: July 2010

Field‐determined estimates of N2 fixation by 15N isotope dilution have not been determined in irrigated annual grain legumes in North America. Nor does knowledge exist as to which nonfixing control plants are most appropriate for these grain legumes when using 15N isotope dilution methods. Within a crop species grown on two Typic Haploboroll soils for 2 yr, lentil (Lens culinaris Medik), fababean (Vicia faba L. minor), and pea (Pisum sativum L.) cultivars adapted to western Canada did not differ in their ability to benefit from symbiotic N2 fixation. When inoculated, N2 fixed averaged 176,84, 216, and 185 kg N ha−1 for chickpea (Cicer arietinum L.), lentil, fababean, and pea, respectively. The percent plant N derived from the atmosphere averaged 82, 67, 85, and 79%, respectively, for the same crops. Response to inoculation was dependent on the crop even though all were infected by Rhizobium leguminosarum Uninoculated chickpea had no nodules or N2‐fixing activity. Inoculation increased N2 fixation in fababean by 19 to 67% and in lentil by 5 to 16% depending on the site. There was a response to inoculation in pea at only one of the two sites. The presence of indigenous soil R. leguminosarum precluded the use of uninoculated treatments as nonfixing controls (except for chickpea) for estimating N2 fixation by 15N isotope dilution. Barley (Hordeum vulgare L. ‘Galt’) or wheat (Triticum aestivum L. emend. Thell ‘Columbus’) appeared to be appropriate control plants for these grain legumes. Because the 15N‐determined fertilizer use efficiency of these controls was similar to that of the N2‐fixing legumes, estimates of N2 fixation by N balance were not significantly different from those obtained by 15N isotope dilution.
Water Status of the Developing Grain of Maize1
Authors: Westgate mark E. , Boyer John S.
Published: July 2010

Developing grain undergoes large changes in water content. Since there are no direct vascular connections between the grain and the maternal plant, grain growth may depend on large osmotic forces. To determine the nature and magnitude of these forces, we investigated the water potential (Ψw), osmotic potential (Ψs) and turgor in the developing grain of maize (Zea mays L.) from anthesis to harvest maturity in three commercial hybrids grown in the field. Grain Ψw, Ψs and turgor were determined using isopiestic thermocouple phychrometry. Seasonal trends in grain Ψw were similar in all three hybrids despite differences in maturity rating (85 to 110 days), maximum grain water content, and environmental conditions after anthesis. Prior to maximum dry matter accumulation (physiological maturity), grain Ψw was 0.4 to 0.9 MPa lower than leaf Ψw reasonably stable, and largely independent of atmospheric conditions. Variations in grain Ψw were similar to the changes in grain Ψs which was between −0.7 and −1.6 MPa and not affected by matric forces. Turgor was usually 0.2 to 0.3 MPa. After maximum dry matter accumulation, grain Ψw responded to atmospheric conditions and decreased rapidly to potentials as low as −8.5 MPa as grain water content decreased and large matric forces developed. The relationship between grain Ψw and percent grain moisture (PM) was similar for all three hybrids and given by PM = 23.7 Ψw−1.16 + 20 (r2 = 0.83). These results indicate either that a large hydraulic resistance exists or that high solute concentrations are present between the developing grain and the vascular supply of the maternal plant. Thus, large osmotic forces are associated with water uptake by the grain. Also, prior to physiological maturity, grain Ψw is controlled mostly by the internal metabolic events associated with development. After physiological maturity, however, it is controlled mostly by grain moisture content.
Herbicide Applications on Wheat and Stubble for No‐Tillage Corn1
Authors: Wicks G. A.
Published: July 2010

No‐tillage corn (Zea mays L.) production following winter wheat (Triticum aestivum L.) is increasing in the central Great Plains. Timely weed control is essential to reduce weed seed production and loss of soil water. This research dealt with the effects of applying herbicides to wheat grown on a fine‐silty, mixed, mesic Typic Argiustolls soil, in North Platte, NE, and herbicide applications 5,20, 35, 50, and 260 days after wheat harvest. Applying metribuzin [4‐amino‐6‐(1,1)‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] to wheat reduced post‐harvest weed biomass 24 to 81%. When herbicide application was delayed until 50 days after wheat harvest, as compared to 5,20, or 35 days, barnyardgrass [Echinochloa crus‐galli (L.) Beauv.] populations before and after corn planting were the highest. The addition of glyphosate [N‐(phosphonomethyl)glycine], paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion), or terbutryn [N‐(1,ldimethylethyl)‐ N'‐6‐(methylthio)‐1,3,5‐triazine‐2,4‐diamine] + 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] to atrazine [6‐chloro‐N'‐ethyl‐N'‐(l‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] sometimes improved corn yields, when applied after wheat harvest, compared with plots treated with atrazine alone. Optimum corn grain yields were obtained when plots treated with atrazine + paraquat at 5, 20, and 35 days after wheat harvest were sprayed with cyanazine {2‐[[4‐chloro‐6‐ (ethylamino)‐1,3,5‐triazin‐2‐yl]amino]‐2‐methylpropanenitrile} preemergence or handweeded once after the corn was planted. Delaying post‐wheat harvest herbicide application for 260 days reduced corn yields 20%.
Effect of Salinity on Grain Yield and Quality, Vegetative Growth, and Germination of Semi‐Dwarf and Durum Wheat1
Authors: Francois L. E. , Maas E. V. , Donovan T. J. , Youngs V. L.
Published: July 2010

Semi‐dwarf bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L., Durum Group) are often grown on saline soils in the western United States. Because of the lack of information on salinity effects on vegetative growth and seed yield of these two species, a 2‐yr field plot study was conducted. Six salinity treatments 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:l by wt). Electrical conductivities of the irrigation waters were 1.5, 2.5, 5.0, 7.4, 9.9, and 12.4 dS/m the first year, and 1.5, 4.0, 8.0, 12.0, 16.1, and 20.5 dS/m the second year. Grain yield, vegetative growth, and germination were measured. Relative grain yields of one semi‐dwarf wheat cultivar and two durum cultivars were unaffected by soil salinity up to 8.6 and 5.9 dS/m (electrical conductivity of the saturated‐soil extract), respectively. Each unit increase in salinity above the thresholds reduced yield of the semi‐dwarf cultivar by 3.0% and the two durum cultivars by 3.8%. These results place both species in the salt‐tolerant category. Salinity increased the protein content of both grains but only the quality of the durum grain was improved. Vegetative growth of both species was decreased more by soil salinity than was grain yield. Both species were less salt tolerant at germination than they were after the three‐leaf stage of growth.
Osmotic Adjustment of Cotton to Moderate Potassium‐Chloride Stress and Subsequent Water Stress During Early Stages of Development1
Authors: Bar‐Tsur A. , Rudich J.
Published: July 2010

High KCl fertilization of drip irrigated cotton (Gossypium hirsutum L.) under intensive growth conditions, mainly in wheat‐ (Triticum aestivum L.) cotton double cropping when the soil profile is dried out and the cotton has a restricted root volume, may cause moderate osmotic stress. Therefore, the response of cotton to KCl stress and successive water stress was evaluated by measurements of leaf water potential (ψL), osmotic potential (ψs) turgor pressure (P), and mineral composition of leaves and flower buds. Young cotton plants (var. Acala SJ2) grown in 10‐L plastic pots filled with a peat/ tuff mixture (1:1) in a field environment were exposed to prolonged osmotic stress for 35 days by application of KCI. Electrical conductivity of the nutrient solutions was 1.5,3.6,6.7,9.8, and 13 dS m−1, and the final ψs of the growth medium at the time of measurement 65 days after planting was 0.05, 0.16, 0.27, 0.38, and 0.47 MPa, respectively. The prolonged 35‐day‐long KCl stress caused stunting of vegetative growth and reduced ψL, which was accompanied by reduction in ψs and maintenance of positive P. Osmotic adjustment was also observed in developing flower buds, but their ψs, was higher than leaf ψs. The main contribution to osmotic adjustment was from the accumulation of inorganic minerals such as K+ and Cl− in leaves and flower buds. Exposure of the control and KCl‐treated plants to successive water stress by withholding irrigation reduced ψL in both treatments. Plants from the KCl treatment responded by a concomitant decrease in ψs, which enabled maintenance of positive P, whereas the control plants that were exposed to water stress did not show osmotic adjustment. The results indicate that prolonged KCl stress enabled the cotton plant to exist and withstand successive water stress, but the cotton plant could not overcome growth inhibition.
Animals for Biological Brush Control1
Authors: Wood G. M.
Published: July 2010

Biological control of undesirable brush species in rundown or abandoned pastures using animals, particularly goats (Capra hircus), is a viable alternative to chemical and mechanical methods. Vermont experiments on a brushy hill pasture (mesic Aeric Hapalaquepts soil) with cattle (Bos taurus typicus), sheep (Ovis aires), and goats showed that the goat was the best animal for the task. Goats reduced the brush in 1 yr and virtually eliminated it from a badly infested pasture in 2 yr. In contrast, 2 yr of grazing were required before cattle and sheep could decrease brush below the ungrazed control. Unlike cattle and sheep, the goats destroyed small trees and saplings by debarking, were not deterred by thorny vegetation, and browsed much higher by standing on their hind legs. As brush was destroyed, grass increased.
Water‐Use Efficiency of Grasses Grown under Controlled and Field Conditions1
Authors: Frank A. B. , Barker R. E. , Berdahl J. D.
Published: July 2010

Forage production from grasses grown in the semiarid northern Great Plains is primarily a function of available water during the growing season. There is a need to develop procedures using controlled environments to shorten the time for identifying germplasm that differs in water‐use efficiency (WUE). Field determination of WUE requires several years to evaluate genetic and environmental effects. This study compares WUE of field grown cultivars of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Shult.], intermediate wheatgrass [Thinopyrum interdium (Host) Barkworth and Dewey], and western wheatgrass [Pascopyrum smithii Rybd. (Löve)] to identical plants grown in a controlled environment. Net CO2 assimilation (A), transpiration rate (E), A/E ratio, and conductances on a leaf basis for plants grown in a controlled environment were compared to WUE calculated from dry matter accumulation and total evapotranspiration for field grown plants. Generally, cultivars within a species that exhibited higher E and A and a lower A/E ratio in controlled environments also had higher field WUE. In contrast, comparisons among species indicated that crested wheatgrass had the lowest E, A, and A/E ratio, but had the highest field WUE. The intercellular C02 concentration (C1) differed among cultivars within species, with the stomates of the higher WUE cultivars functioning to maintain higher c1. Correlations of field WUE with controlled environment measurements suggest that the A/E ratio is not a good predictor of field WUE for the species examined in this study.