bluuebunny/crossref_metadata_2025 huggingface dataset:
Irrigation Interval as a Factor in Sweet Corn Response to Salinity1
Authors: Shalhevet J. , Vinten A. , Meiri A.
Published: July 2010

Shortening irrigation intervals with saline water is expected to reduce salinity damage by increasing the mean soil water content and thereby reducing the mean solute potential. Evidence is lacking in support of this hypothesis. This study tested the hypothesis by determining the interaction of irrigation water salinity and irrigation interval on sweet corn (Zea maysL. var. Jubilee) growth, yield, and water uptake. The field experiment consisted of 3.5, 7‐, 14‐, and 21‐day irrigation intervals and irrigation water salinities, ECl, of 1.7, 4.0, 5.3, 7.9, and 10.2 dS/m in a factorial design using regression analysis. The soil was a Calcic Haploxeralf. The amount of water at each irrigation was applied to replenish the soil water deficit as measured with the neutron scattering method. The regression of absolute yield on mean electrical conductivity (EC) of the soil saturation extract, EC, showed a steeper yield decrease with increasing EC, for the 3.5day than for the 75‐, 14‐, and 21‐day intervals. On the other hand, the relative yield, Y, response to salinity showed the same benefit of shortening the irrigation interval with saline as with nonsaline water. This lack of interaction on relative yield was due to an increase in mean ECe. from 4.4 to 5.4 dS/m as irrigation interval was shortened from 21 to 3.5 days. LeafCl−and Na+content tripled from 11.2 and 0.43 to 37.4 and 1.14 g/kg dry matter, respectively. The K+content increased from 19.4 to 26.4 g/kg, while the Ca content was unaffected as ECl, increased from 1.7 to 10.2 dS/m.
Effect of Nitrogen on Root Growth of Two Corn Genotypes in the Field1
Authors: Mackay A. D. , Barber S. A.
Published: July 2010

Corn (Zea mays L.) genotypes vary in their response to applied N fertilizer. Nitrogen uptake by the plant is controlled by N influx at the root surface and the size and morphology of the root system. The objective of this study was to investigate the effect of applied N on mean N influx and root growth of two genotypes that differed in their response to N. Nitrogen rates were 0 and 227 kg ha−1 for ‘Pioneer 3732’ and ‘B73✕Mo17’ grown on Raub silt loam (Aquic Argiudolls) and 227 kg N ha−1 on Chalmers silt loam (Typic Haplaquolls). Root growth, plant weight, and N content were measured 31,47,61,75,91 and 109 days after planting. Apart from an initial difference at 31 days, mean N influx of roots of both genotypes were similar. Root length and root surface area of Pioneer 3732 were not increased by the application of N. In contrast, applied N increased root growth of B73✕Mo17. By midsilk (75 days) root length of B73✕Mo17 was 36 and 39% greater than that of Pioneer 3732 on the Raub and Chalmers soils, respectively, to which N was applied. The greater root growth of B73✕Mo17 and the continued root growth of this hybrid after midsilk appears to be one possible mechanism to explain the greater growth of this hybrid under a high‐N fertilizer regime. This requires further verification under a wider range of environmental conditions. A lack of moisture limited the grain yields of both hybrids in this study.
Root Development of Sericea Lespedeza and Alfalfa in Acid Soils1
Authors: Joost R. E. , Hoveland C. S.
Published: July 2010

A more thorough understanding of sericea lespedeza [Lespedeza cuneata (Dum.) G. Don] root system development is needed to improve management of seedling stands during establishment, especially in acid subsoils, which often limit root development of legumes. A greenhouse experiment was conducted using glass‐front root boxes to quantify seedling root system development of five lines of sericea lespedeza and ‘Apollo’ alfalfa (Medicago sativa L.) in acid (high AI and Mn) and limed soil layers underlying limed surface soil. The root boxes were partitioned into six 12.5 cm by 12.5 cm by 80 cm deep sections and each section was packed with Bradson clay loam (clayey, oxidic mesic Typic Hapludults) topsoil. Root growth rate (GR) and rooting intensity (cm cm−2 viewing surface) were monitored by tracing daily root growth on mylar sheets covering the glass front of the boxes. Measurements of root GR in limed subsurface soil indicated that alfalfa taproots elongated at twice the rate of the sericea entries evaluated. Alfalfa root GR was reduced by 69% in unamended soil, whereas root GR was not reduced in three sericea lines in the unamended treatment. Rooting intensity of 0.79 in alfalfa was twice that of sericea; however, in acid soil, abnormally branched and swollen secondary roots represented a large portion of the alfalfa root system. In addition, secondary taproot growth (thickening) in alfalfa was reduced 30% in both the surface and subsurface soil of the unlimed treatment. Root/shoot ratios based on root length in limed subsoil indicated that sericea produces more root growth per unit shoot than alfalfa.
Selenium Uptake in Astragalus and Lupinus Species1
Authors: Davis A. M.
Published: July 2010

Forage quality potentials of plant introductions are unknown when introduced into the USA. Some native species of Astragalus are known to be Selenium (Se) accumulators and it is possible that some introductions could be accumulators also. This greenhouse study was undertaken to determine which, if any, of the untested 103 Astragalus and 68 Lupinus accessions were Se accumulators. Each accession was present in four replicates arranged in a randomized complete block design. Accessions were harvested at 24 weeks of age and the forage dried and analyzed. The AOAC extraction procedures were used and quantification was by colormetric turbidometric methods. Species of Astragalus accumulated Se in varying amounts from none to 61 mg kg−1. None of the species of Lupinus accumulated Se at a potentially toxic level when grown in a soil mix (equal parts v/v: Shamel loam/quartz sand/commercial peat), that contained 18 mg kg−1 Se. These studies indicate that plants from 66 of the 103 Astragalus and none of the 68 Lupinus accessions might accumulate toxic amounts of Se if grown on seleniferous soils. However, other unknown factors may make them unsuited for forage.
Effects of Reduced Tillage Practices on Continuous Wheat Production and on Soil Properties1
Authors: Izaurralde R. C. , Hobbs J. A. , Swallow C. W.
Published: July 2010

Acceptance of reduced‐ and no‐tillage systems in continuous winter wheat (Triticum aestivum L.) production has been limited in the past because of decreased yields, detrimental crop‐residue effects on seedlings and crop growth, and straw management problems. A field study conducted at Manhattan, KS for 3 yr assessed the effects of residue management (untreated, mowed, and burned), tillage treatments (conventional, reduced, and no‐tillage), and two methods of seed placement on plant density and grain yield of winter wheat, and on soil properties. The study area was mapped as Smolan sicl (fine, montmorillonitic, mesic, Pachic Argiustolls) and Wymore sicl (fine, montmorillonitic, mesic, Aquic Argiudolls). Lack of adequate seed placement due to the presence of surface residues under reducedand no‐tillage conditions reduced wheat yields. Increases in soil bulk density and resistance to penetration in no‐tillage treatments did not significantly affect wheat yields when seed was properly placed. Under relatively dry environmental conditions (1980–1981), no‐tillage wheat yield was higher than on conventional tillage (2.37 and 2.01 Mg/ha, respectively). Under such conditions, total soil water content in the upper 84 cm was higher on no‐tillage than on conventionally tilled plots. Maximum soil temperatures at the 5‐cm depth were 3°C lower on no‐tillage than on conventional tillage treatments.
Sodic Calcareous Soil Reclamation as Affected by Different Amendments and Crops1
Authors: Robbins C. W.
Published: July 2010

Sodium leaching efficiencies (moles of Na removed per unit leachate volume) were measured and compared from four noncropped and four cropped treatments applied in duplicate to 1.0 m deep sodic calcareous silt loam in lysimeters. Treatments included a check, gypsum, chopped alfalfa (Medicago sativa L.), fresh manure, alfalfa, sorghum (Sorghum bicolor), Sudan grass (Sorghum Sudanese) hybrid (which will be called sorghum hybrid for simplicity), sorghum hybrid + leaching, and cotton (Gossypium hirsutum L.). The sorghum hybrid + leaching treatment soil was leached with tap water until 0.5 pore volume of leachate was collected from lysimeter bottoms, and then sorghum hybrid was planted. Sorghum hybrid was the most efficient treatment in reclaiming Na‐affected soil. All four non‐cropped soils eventually became dispersed in the lower part of the profile and hydraulic conductivity became very low. Cropped treatments continued to conduct water at a satisfactory rate for reclamation; however, due to low water use, cotton treatment produced a low total Na removal. Sorghum hybrid shows promise as a crop that could be used to speed reclamation of sodic calcareous soils. The treatments producing the highest sodium removal efficiencies also produced the highest soil atmosphere CO2 concentrations. By selecting crops, amendments, and water application rates and timing, calcareous sodic soil reclamation can very likely be accomplished faster and more economically than in the past.
Field Evaluation of Urease Inhibitors for Corn Production1
Authors: Schlegel A. J. , Nelson D. W. , Sommers L. E.
Published: July 2010

Phosphoroamide urease inhibitors were evaluated for their ability to increase N uptake and grain yield of corn (Zea mays L.) when added to surface‐applied urea fertilizers. Six urease inhibitors [trichloroethyl phosphorodiamidate, diethyl phosphoric triamide, dimethyl phosphoric triamide, N‐(diaminophosphinyl)‐cyclohexylamine, N‐benzyl‐N‐methyl phosphoric triamide, and phenylphosphorodiamide (PPD)] were evaluated. Urea prills, urea solution, and urea–ammonium nitrate (UAN) solution were broadcast, and UAN solution was banded onto the surface of conventional till (CT) Chalmers silty clay loam (Typic Haplaquoll) and no‐till (NT) Raub silt loam (Aquic Argiudoll) in 1983. Two urease inhibitors [PPD and N‐(n‐butyl)‐thiophosphoric triamide (TPT)] were broadcast with urea prills and UAN solution (60, 120, and 180 kg N ha−1) onto CT and NT Chalmers and NT Avonburg silt loam (Aeric Fragiaqualf) soils in 1984. With both tillage systems in 1983, urea prills produced greater grain yield and tissue N content than did UAN solution, although no differences between broadcasted and banded UAN or between fertilizers with and without urease inhibitors were observed. In 1984, urease inhibitors increased grain yield and N uptake of NT corn when applied with urea prills, but not with UAN solution. When conditions existed for substantial NH3 loss, TPT performed as well or better than PPD. Urease inhibitors will be most beneficial when added to urea that is surface‐applied to soils with large amounts of residue cover under conditions of adequate moisture to promote urea hydrolysis and ammonia volatilization but without sufficient precipitation to move the urea into the soil.
Phenology of Dent Corn and Popcorn. I. Analysis of Repeated Measurements from Phenology Experiments1
Authors: Stevens E. J. , Eskridge K. M. , Stevens S. J. , Flowerday A. D. , Gardner C. O.
Published: July 2010

Repeated observations are commonly made on individual or multiple plant samples in order to generate data suitable for developing linear regression models with growth stage as the dependent variable. Most studies using regression, including those conducted at the University of Nebraska, Lincoln (UNL), have implicitly assumed that the data adhere to standard regression assumptions even though these assumptions may be tenuous. Misleading conclusions can be made if basic regression assumptions are not reasonably satisfied. Pilot studies may be used as a strategy for completing preliminary analyses of representative data from a larger phenology study to develop appropriate regression models and substantiate basic regression assumptions. The objectives of this research were to (i) validate regression models used in an interactive agrometeorology (AGNET) offered by UNL (ii) correctly specify thermal‐photoperiod regression models of corn phenology using hourly data generated by an automated weather station, (iii) investigate the validity of underlying assumptions of models developed, and (iv) investigate the application of growth curve analysis as a statistical procedure for comparing response profiles of different treatment effects in corn phenology experiments. A 2‐yr phenology study incorporating three planting dates, one dent corn cultivar (B73 ✕ Mo17), and three differently maturing popcorn cultivars (P410, P609, and Iopop 12) was conducted in eastern Nebraska during 1982‐1983. Climate records from an automated weather data network were used to develop daily and hourly heat sums. Corn growth was described using both current and modified staging procedures. Serious violations of standard regression assumptions were identified in the UNL‐AGNET corn phenology model and were commonly associated with one or more of the following conditions: (i) using incorrectly specified models, (ii) heterogeneity of error variance, and (iii) nonindependence of errors. Violations were considered serious since they were suspected of producing biased mean squares and regression estimates, indicating a need for further refinement of model definitions and growth staging procedures. Alternative regression models were developed and tested using a modified staging procedure combined with partitioning and modeling phenological sequences as pre‐ and post‐anthesis development. When applied to these data, growth curve analysis demonstrated a curvilinear response of corn phenology to planting date (daylength) within the range of 14.3 to 15.2 h, and provided a useful alternative to standard regression techniques for statistically analyzing data from corn phenology experiments.
Herbicide Compatibility and Phytotoxicity When Mixed with Liquid Fertilizers1
Authors: Sander Kip W. , Burnside Orvin C. , Bucy John I.
Published: July 2010

The need for growers to conserve energy, labor, and money has stimulated the joint application of herbicides and liquid fertilizers. Chemical and physical reactions between herbicides and liquid fertilizers may affect the compatibility or herbicidal performance of a combination. The objective of this research was to determine the compatibility and phytotoxic characteristics of 10 common herbicides when individually mixed with each of six liquid fertilizers. Of the 60 herbicide‐liquid fertilizer combinations tested, 87% were compatible and 13% were incompatible. Attapulgite clay suspensions were the most compatible of the liquid fertilizers tested. Atrazine (6‐chloro‐N‐ethyl‐N'‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] and metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4‐triazin‐5(4H)‐one] were least compatible with the liquid fertilizers. Phytotoxicity of the herbicide, when combined with the liquid fertilizers, increased in 21%, decreased in 32%, and was equal to the herbicide‐water check in 47% of the combinations. Glyphosate [N‐(phosphonomethyl)glycine] and paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) showed the highest occurrence of decreased phytotoxicity, whereas acifluorfen {5‐[2‐chloro‐4‐(trifluoromethyl)phenoxyl‐2‐nitrobenzoic acid} and bentazon [3‐(1‐methylethyl)‐(1H)‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide] showed the highest occurrence of increased phytotoxicity when mixed with liquid fertilizers. Agitation was necessary to prevent separation in 52% of the compatible mixtures. Duration of contact between herbicide and liquid fertilizer did affect herbicidal phytotoxicity with certain combinations and especially with butylate [S‐ethyl bis(2‐methylpropyl) carbamothioate]‐liquid fertilizer mixtures.
Mefluidide Applications for Annual Bluegrass Seedhead Suppression Based on Degree‐Day Accumulation1
Authors: Danneberger T. K. , Branham B. E. , Vargas J. M.
Published: July 2010

Mefluidide [N‐(2,4‐dimethyl‐5‐{[(trifluoromethyl)sulfonyl] amino}phenyl) acetamide] is an effective growth regulator for annual bluegrass [Poa annua var. reptans (Hauskins) Timm.] seedhead suppression. The effectiveness of mefluidide is dependent on the rate and timing of application. The objective of this field study was to determine the lowest effective rate and the proper time for mefluidide application based on growing degree‐days (GDD). Soil types were a fine, mixed, mesic Aeric Ochraqualf and fine‐loamy, mixed, mesic Typic Glossoboric Hapludalfs for Columbus, OH, and East Lansing, MI, respectively. The rates evaluated were 0.140, 0.070, and 0.035 kg ha−1 of mefluidide. The applications were made at 15, 25, 30, and 45 GDD. Degree‐days were accumulated using a sine curve as an approximation of the diurnal temperature curve. The base temperature used was 13°C. Mefluidide applied between 15 and 30 GDD at 0.140 kg ha−1 gave excellent seedhead suppression. Mefluidide applied between 15 and 30 GDD at 0.070 kg ha−1 gave moderate seedhead suppression. Applications of mefluidide at 45 GDD or at the 0.035 kg ha−1 rate were unacceptable.
Fungal Endophyte Infection‐Loline Derivative Alkaloid Concentration of Grazed Tall Fescue1
Authors: Belesky D. P. , Robbins J. D. , Stuedemann J. A. , Wilkinson S. R. , Devine O. J.
Published: July 2010

Impaired animal performance on tall fescue (Festuca arundinacea, Schreb.) pasture has been associated with the presence of a fungal endophyte (Acremonium coenophialum). A number of alkaloids, including the loline derivatives N‐formyl and N‐acetyl loline, occur in endophyte infected tall fescue. A study was conducted at Watkinsville, GA, on a Cecil sandy loam (Typic hapludult) to examine the influence of N fertilization and season on endophyte infection frequency (EIF) and loline derivative alkaloid concentration (LDA) of grazed low and high endophyte tall fescue. Paddocks (0.7 ha) established with low and high endophyte status ‘Ky‐31’ tall fescue seed were fertilized with 134 and 336 kg N ha−1 (22 factorial) and replicated three times. Endophyte infection frequency was greater in high than low fungus paddocks during the 3‐yr study. Endophyte infection frequency means within a given paddock, i.e., high or low fungus, remained relatively constant in 1983 and 1984 but increased by 50% in high and 100% in low fungus paddocks in 1985. Endophyte infection frequency was not affected by N nor did infection frequency vary significantly within a growing season. Loline derivative alkaloid concentration and EIF were significantly correlated (positive) in each growing season. High fungus paddocks had significantly greater (100%) LDA than low fungus paddocks. The ratio of LDA to EIF was greater under high N and high fungus conditions in the fall of 1983 and in 1984. Periods of LDA production may be more closely associated with short‐term weather conditions than absolute EIF. The relationship between LDA and EIF may not be simply defined in continuously grazed tall fescue, especially under moderate EIF.
Temperature Effects on Leaf Anatomy, Phenolic Acids, and Tissue Digestibility in Tall Fescue1
Authors: Akin D. E. , Fales S. L. , Rigsby L. L. , Snook M. E.
Published: July 2010

Increasing growth temperature lowers digestibility of tall fescue (Festuca arundinacea Schreb.) cell walls, but specific tissue responses have not been fully elucidated. The objectives of our research were to determine the effect of increasing growth temperature on leaf anatomy, histological reactions for lignin, alkali‐extractable phenolic acids, and the digestion of different tissue types by rumen microorganisms after 4, 10, 24, or 48 h. Plant material was grown in a controlled environment in which temperature was changed sequentially from 13/10°C (T1), to 20/18°C (T2), to 30/27°C (T3), and back to 13/10°C (T4). Two consecutive harvests of uppermost leaf blades following 28 days growth were made at each temperature, and analyses were performed on leaf blades. Histological reactions for lignin and leaf anatomy were similar for all treatments but with higher amounts of lignified vascular tissue in T3. At incubation times less than 48 h, leaf tissues from plants grown at T1 or T4 were degraded, as determined by scanning electron microscopy, to a greater extent than those at T2 or T3. However, after 48 h, tissues from plants grown at T2 were clearly the most degraded, and the order for all digestible tissues was as follows: T2 > T4 > T1 > T3. From 786 to 854 g kg−1 of the phenolic acids extracted from forage with 1 M NaOH were trans‐p‐coumaric and trans‐ferulic acids. Increases in growth temperature tended to increase levels of these and other phenolic acids, with T3 resulting in the highest level; amounts at T1 were lower (P≤10.05) than those at T2 through T4. Increased temperature resulted in a lower digestibility of easily degraded tissues without causing a marked change in leaf anatomy or histological reaction for lignin. Increased levels of p‐coumaric and ferulic acids up to T3 suggest that these compounds may contribute to limiting the digestibility of leaf blade tissues at higher temperatures.
Variation in Seed Size in Soybean1
Authors: Egli D. B. , Wiralaga R. A. , Ramseur E. L.
Published: July 2010

Seed size (mass per seed) is an important yield component in soybean [Glycine max (L.) Merr.]; however, little is known of the variation in seed size within a seed lot. Consequently, the variation in seed size within seed lots collected from greenhouse and field experiments was investigated. Treatment variables included in the experiments were planting dates, cultivars (determinate and indeterminate), and source‐sink alterations applied during seed filling. Seed size distributions were determined using round‐hole screens ranging from 3.2 to 8.7 mm in diameter at intervals of 0.8 mm. All seed lots investigated exhibited a wide range in seed size from approximately 90 to greater than 200 mg seed−1. However, 40 to 80% of the seeds stayed on a single screen. The seed size of seeds on a single screen varied significantly among cultivars, planting dates, and years. Determinate cultivars tended to have a greater proportion of the seed on a single screen, but the range in seed size was similar to that exhibited by indeterminate cultivars. Treatments that altered mean seed size usually affected the proportions of the various sized seeds in the lot, more than the range in seed size. Variations in seed size within a seed lot were not associated with differences in seed density, specific seed coat mass, or seed N concentration. The data indicate that variation in mean seed size can be caused by variations in the proportion of the various sized seed in the seed lot, with relatively small changes in the range in seed size.
Effects of Tillage Practices on Cotton Double Cropped with Wheat1
Authors: Baker Shelby H.
Published: July 2010

To reduce production cost, reduce land erosion and increase profits per acre, double cropping and reduced tillage are becoming a part of production systems across the United States. Tillage studies with double crop (DC) wheat (Triticum aestivum L.) and cotton (Gossypium hirsutum L.) were conducted at two Georgia locations, Tifton (1982–1984) and Plains (1981–1984). At Tifton, continuous tillage treatments (same treatments on the same plot every year) were: a winter fallowed full‐season (FS) check; no‐tillage (NT), cotton planted into straw and stubble; burn no‐tillage (BNT), plots burned, no other tillage; maximum tillage (MXT), plots burned and bottom plowed; minimum tillage (MTH), plots burned and disc harrowed; and minimum tillage (MTRH), plots burned, subsoiled, and bedded (riphip). The treatments at Plains were non‐continuous (test rotated to new area each year) and did not include a FS or MTRH treatment. The DC cotton at Tifton showed a significant yield reduction when compared with the FS cotton, regardless of DC tillage treatment. Within tillage treatments, continuous MXT, MTH, or MTRH had no significant effect on cotton yield, but the average yield of the tilled treatments over years was significantly better than those of the NT and BNT treatments. In certain years the BNT treatment yield was equal to some of the tilled treatments. Yield of the BNT treatment was significantly better than the NT treatment. At Plains, the average yields of the BNT, MTH, and NT treatments were not significantly different, but the BNT was significantly better than the MXT treatment. The MXT and MTRH treatments produced a higher lint percent than FS, but there were no differences in the DC tillage treatments at Tifton. Boll size and fiber characteristics were similar for DC and FS cotton at Tifton. The MXT treatment at Plains produced larger bolls than did the other treatments, but there was no treatment effect for lint percent and fiber properties. Wheat yields at Tifton were not affected by cotton tillage treatments.
Response of a Rice‐Sugarcane Rotation to Calcium Silicate Slag on Everglades Histosols1
Authors: Anderson D. L. , Jones D. B. , Snyder G. H.
Published: July 2010

Rice (Oryza sativa L.) and sugarcane (Saccharum spp.), grown on organic soils of the Everglades, have been shown to respond favorably to the application of Si from calcium silicate slag. Since these crops may be grown in rotation, it is important to know if slag applied to one crop will benefit the second crop. The objective of the study was to determine the response of rice and sugarcane grown on a Terra Ceia muck (Euic, hyperthermic Typic Medisaprist) to calcium silicate slag applied prior to planting rice, and to slag applied before the planting of sugarcane. Five rates of slag were applied for production of a rice crop, after which time the same plots were planted to sugarcane. Other plots received the same rates of slag just prior to planting sugarcane. Slag applications increased both rice straw Si and sugarcane leaf Si concentrations. A single application of slag prior to planting rice increased production of both the rice and sugarcane crops in the rotation. The combined plant and ratoon rice grain yields were significantly increased 50% by slag application. Slag application also increased harvested cane (biomass) yields 23%, and sugar yields by 25%. Somewhat greater sugarcane plant responses were observed from slag applied immediately before planting than from slag applied before the rice and cane rotation treatment. On the average, slag applied at 20 Mg ha−1 before rice increased sugar yield by 16%, compared to a 21% increase when slag was applied before cane.
Comparison of Turnip‐Chinese Cabbage Hybrid, Rape, and Rye, Alone and in Combination with Annual Ryegrass and Crimson Clover1
Authors: Dunavin L. S.
Published: July 2010

Small grains, Italian ryegrass (Lolium multiflorum Lam.), and crimson clover (Trifolium incarnatum L.) have been used extensively for cool‐season pastures. Rape (Brassica napus L.), turnip (B. rapa L.), and hybrids thereof are possible alternatives that need investigating. A turnip‐Chinese cabbage hybrid [B. campestris var. rapa L. × B. pekinensis (Lour.) Rupr.], rape, rye (Secale cereale L.), ryegrass, and crimson clover were grown in a field experiment in monoculture and mixtures during 3 yr, on a Dothan fine sandy loam soil (fine‐loamy, siliceous, thermic Plinthic Paleudult). The mixtures and the ryegrass monoculture produced more dry matter (DM) and digestible organic matter (DOM) than the other monocultures. There was more variability between mixtures and monocultures with respect to crude protein (CP). The turnip hybrid was relatively unproductive for the whole season; however, when first‐harvest yields were considered, its value for early season production was apparent in that it was high producer of DM in all years and at the top in 2 yr for production of CP and DOM. The turnip hybrid‐ryegrassclover mixture, at the first harvest, was among the best in production of DM, DOM, and CP in 2 yr and was equal to the rye‐ryegrassclover mixture in production of DM, DOM, and CP at the first harvest in all years, The yield of DM, DOM, and CP from rape, at the first harvest, was equivalent to the high yield in only 1 yr. Rye was a top producer, at the first harvest, of DM, CP, and DOM, and ryegrass and clover had low first‐harvest yields. The turnip hybrid appears to be a reasonable alternative to rye in cool‐season mixtures with ryegrass and clover but less valuable than rape or rye in monoculture except for early season forage
Tall and Semidwarf Wheat Response to Dryland Planting Systems1
Authors: Winter S. R. , Welch A. D.
Published: July 2010

Dryland winter wheat (Triticum aestivum L.) yields on the Southern Great Plains are almost always limited by crop water deficits. This research was conducted to determine if a wide‐row planting system in combination with a high‐yielding, semidwarf wheat would increase plant height, leaf conductance, leaf water potential, and grain yield of dryland wheat. ‘Scout 66’, a tall wheat, and ‘TAM 105’, a semidwarf, were planted in five row‐spacing systems on Pullman clay loam soil (fine, mixed, thermic Torrertic Paleustoll) at Bushland, TX. Two narrow‐row systems (0.20‐ and 0.25‐m row spacing) and three wide‐row systems (0.51‐m single rows and 0.25/0.51‐m and 0.25/0.76‐m skip‐row systems) were studied. Total soil water depletion was not affected by row‐spacing system or cultivar in either year. Wide‐row systems were, however, effective in economizing usage of soil water before boot stage so more water was available in widerow systems during later growth stages in 1985. As a result, leaf conductance and leaf water potential at the boot stage in 1985 were increased from 2.21 mm s−1 and —1.38 MPa, respectively, in wheat growing in the 0.20‐m row‐spacing system, to 4.24 mm s−1 and —0.85 MPa in wheat growing in the 0.51‐m row‐spacing system. Wide‐row systems increased plant height of TAM 105 by 0.07 m. While using semidwarf wheat in wide‐row systems was successful in reducing crop water deficit and increasing plant height, grain yield was reduced in wide‐row systems compared to narrow‐row systems for both tall and semidwarf wheat.
Winter Wheat Production as Influenced by Fallow Method, Seeding Method, and Nitrogen Fertilization1
Authors: Tanaka D. L. , Aase J. K.
Published: July 2010

Use of conservation tillage practices for erosion control retains more crop residue on the soil surface and alters plant environments. The objectives of a study conducted on a Williams loam (fine‐loamy, mixed Typic Argiboroll) were to determine the effects of fallow method, seeding method, and N rates on winter survival and production of winter wheat (Triticum aestivum L.). Factorial treatment combinations of fallow method (stubble mulch, reduced tillage, and chemical fallow) and seeding method (deep‐furrow and double‐disk) were whole plots, with N rates (0, 34, and 68 kg/ha) as subplots. Winter survival as determined from stand counts taken in late October and again in April was 100% for each year and treatment except in 1984 when deep‐furrow seeded wheat had a 13% reduction in stand. Winter soil temperatures at 30‐mm depth in deep‐furrow seeded plots were 1 to 3°C higher than in double‐disk seeded plots. Snow insulating effects were achieved with fallow methods that left residue erect, resulting in good winter survival on double‐disk seeded plots. Reduced tillage and chemical fallow reduced grain yields in 1981 but had no influence in the other years. Double‐disk seeded wheat yielded 200 to 400 kg/ha more grain than deep‐furrow seeded wheat. Grain N concentration was 0.9 to 1.8 g/kg less in double‐disk seeded wheat than in deep‐furrow seeded wheat. These data support use of conservation tillage methods to maintain crop productivity and to reduce soil erosion.
Effect of Biocidal Treatments on Cation Exchange Capacity and Fusarium Blight of Soybean in Delaware Soils
Authors: Sandler H. A. , Carroll R. B. , Sparks D. L.
Published: July 2010

Fusarium wilt has caused significant losses in soybean [Glycine max (L.) Merr.] production and is very difficult to control because it is caused by the soil‐borne fungus Fusarium oxysporum. A better understanding of the relationship between soil characteristics and the pathogen and between biocidal treatments and physiochemical properties is needed, especially for soils that appear to be suppressive. The effects of antoclaving and Vapam fumigation on cation exchange capacity, organic matter content, clay content, pH, and Fusarium wilt of soybean were determined for several different Delaware soil types (Typic Hapludults, Typic Qnartzipsamments, and Typic Umbraquults). ‘Essex’ soybean was grown in the treated soils that had been infested, prior to planting, with 6.3 × 104 viable spores per gram of dry soil of a pathogenic Fusarium oxysporum isolate. Treatments were arranged on the greenhouse bench in a randomized completeblock design with five replications. Cation exchange capacity generally increased with fumigation and decreased with autoclaving, but differences were not significant for all soils. Organic matter content increased following fumigation in three soils, and pH values were lowered by both biocidal treatments in all soils except a Matapeake silt loam. Disease incidence and severity were affected differently for each soil type.
Reed Canarygrass Binary Mixtures with Alfalfa and Birdsfoot Trefoil in Comparison to Monocultures
Authors: Jones T. A. , Carlson I. T. , Buxton D. R.
Published: July 2010

Maintenance of both components in a grass‐legume mixture is an important objective of temperate perennial grassland management, yet one species is often lost from the stand within a few growing seasons. Our objective was to study factors that influence the persistence of reed canarygrass (Phalaris arundinucea L.) in binary mixture with alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.). Two divergent cycle‐2 specific leaf weight (SLW) populations of reed canarygrass were grown in binary alternate‐row mixture under a three‐cut‐per‐year management with each of four legume cultivars: Olympic and Baker alfalfa and Norcen and Dawn birdsfoot trefoil. By the eighth harvest, alfalfa had competitively excluded reed canarygrass. Calculations of relative yield total indicated that competition between alfalfa and reed canarygrass was for de Wit's different space (the two species limited by different factors to at least some extent and therefore at least somewhat complementary in their exploitation of environmental resources) at early harvests. Birdsfoot trefoil mixtures reached equilibrium by the spring after establishment, with botanical composition thereafter varying from 67 to 81% legume. In contrast to alfalfa‐reed canarygrass mixtures, competition between birdsfoot trefoil and reed canarygrass was for the same space (the two species strictly limited by and competing for the same factors) at early harvests and for different space at late harvests. No yield differences between SLW populations were found in mixture, although high SLW yielded 19% more than low SLW in monoculture over eight harvests. Reed canarygrass had higher in vitro digestible dry matter concentration in mixture than in monoculture as long as reed canarygrass yields in mixture did not exceed yields in monoculture. Legumes were taller and more mature in mixture than in monoculture at early harvests. Increased height and advanced maturity may be mechanisms responsible for the legume's dominance. Performance of forage species for agronomic and quality traits in monoculture, however, did not predict their performance in mixture.
Canopy Carbon Dioxide Profile in Relation to Row Spacing of ‘Essex’ Soybean
Authors: Francis Paul B. , Parks W. L.
Published: July 2010

Little field work has been done on how row spacing in soybean [Glycine max (L.) Merr.] alters the canopy microclimate. Canopy CO2 profiles were measured for ‘Essex’ soybean planted in 0.25‐, 0.38‐, and 0.51‐m row spacings with or without a wheat (Triticum aestivum L.) straw mulch (4.5 Mg ha−1) in 1983, and in 0.13‐, 0.25‐, 0.51‐, and 0.76‐m row spacings with no mulch treatment in 1984, under irrigation on Sequatchie loam (a fine‐loamy, siliceous, thermic Typic Hapudult). Canopy CO2 for individual treatments and days was modeled as a function of time of day and height, with R2 values ranging from 0.52 to 0.97. Analysis of covariance for pooled data during reproductive growth indicated significant differences in CO2 among row spacings in the upper three fourths of the canopy. Upper canopy level CO2 was 5 to 15 µL L−1 lower after midday but slightly higher at dusk in the narrower versus wider row spacings and seemed related to a higher leaf density. Mulching did not influence canopy CO2. After midday, the CO2 in the row middles was 5 to 10 µL L−1 lower than over the drill for the 0.76‐m row spacing, which had incomplete canopy closure. Horizontal deviations in CO2 were not evident in the treatments that had complete canopy closure. Carbon dioxide profile variations observed among row spacings seemed to be highly related to leaf area density.
Hybrid Hard Red Spring Wheat Seed Production Potential
Authors: Howey S. J. , Spilde L. A. , Edwards I. B. , Laskar W. J.
Published: July 2010

The success of cytoplasmic male sterile (CMS) hybrid wheat (Triticum aestivum L.) depends greatly on the female seed production potential. Objectives of this experiment were to evaluate male sterile seeding rate and pollinator planting delay in relation to CMS or chemical hybridizing agent (CHA) production systems on hybrid hard red spring wheat seed yield. Field experiments were conducted on a Wheatville silt loam (course‐silty, over clayey, frigid Aeric Calciaquoll) at Kragnes, MN. Spikes were wind and hand pollinated to compare CMS and CHA stigma receptivity during flowering. A CMS (Triticum timopheevi Zhuk. cytoplasm) line was used in 1984 and 1985. A CHA version was obtained in 1985 by applying SD 84811. Male steriles were planted at 22.4, 56.0, and 89.6 kg ha−1 in each of three crossing blocks, which were characterized by pollinator planting delays of 0, 68, and 136 growing degree days (GDD) in 1984, and 0, 85, and 170 GDD in 1985. The highest CMS female yield (2.0 Mg ha−1) utilized the 89.6 kg ha−1 rate and 68 GDD delay in 1984. Positive relationships were observed in 1984 between yield and pollinator delay for the 22.4 kg ha−1 rate, while higher rates had similar but limited yield responses. CMS yields were more than 200% of CHA yields. CMS stigma receptivity periods were similar over years. CMS and CHA stigma receptivity periods were similar for duration and time of peak intensity, but CHA seed sets were generally lower. Additional knowledge on flowering characteristics, environmental interactions, and genotypic compatibility with CHAs may be necessary before hybrid hard red spring wheat production becomes a viable option.
Fall Harvest Management of Alfalfa. II. The Implications of Photosynthesis, Respiration, and Taproot Nonstructural Carbohydrate Accumulation on Fall Harvest Management
Authors: Edmisten K. L. , Wolf D. D.
Published: July 2010

Alfalfa (Medicago saliva L.) harvests may be delayed by rainfall, environmental conditions that retard growth, or unfavorable weather for hay curing. Fall harvests may be delayed until dates that may affect winter survival. Harvests made between 20 September and 20 October have generally been considered detrimental to alfalfa stands in geographical areas such as western Virginia, presumably because regrowth depletes reserves needed for winter survival and spring growth. The objective of this study was to determine if photosynthesis following late harvests can help offset losses of total nonstructural carbohydrates (TNC) in taproots and allow more flexible fall harvest management than is currently recommended. ‘Arc’ alfalfa was managed to achieve 50 d of growth prior to final fall harvests made 16 September or 2, 16, or 30 October for 2 yr. The soil was a mixture of Landisburg silt loam (fine‐loamy, mixed, mesic Typic Fragiudult) and Greendale silt loam (fine‐loamy, siliceous, mesic Fluventic Dystrochrept). Gross photosynthesis, plant respiration, and TNC were measured at 2‐wk intervals in the fall following each final fall harvest. In a parallel study, three levels of shade were imposed following each fall harvest date to evaluate the influence of photosynthetic rate on TNC levels and plant persistence. Fall regrowth and plant maintenance were not dependent on root TNC accumulation, and TNC levels ranged from 234 to 295 g kg−1 by 15 December. Photosynthesis offset respiration losses for regrowth and maintenance during the fall. High photosynthetic rates (1.0 to 19.9 μmol CO2, m−2 s−1), compared to respiration (0.1 to 4.2 μmol CO2, m−2 s−1), on a land‐area basis were possible due to temperatures occurring within the optimum range for photosynthesis of alfalfa during 68% of the daylight hours from September through November. Slow regrowth, low respiration rates, and relatively high photosynthetic rates resulting from cool temperatures limited TNC losses following fall harvests. This favorable environmental period lasts much longer in Virginia than at northern latitudes, where most fall harvest management research has been conducted, and allowed sufficient recovery of alfalfa harvested with 50 d of growth in the fall.
Potential of Inhibitors for Increasing Response of Lowland Rice to Urea Fertilization
Authors: Buresh R. J. , De Datta S. K. , Padilla J. L. , Chua T. T.
Published: July 2010

The full potential of biological inhibitors to increase the yield response of lowland rice (Oryza sativa L.) to urea fertilization has remained uncertain, because no chemical has been available to completely eliminate all gaseous loss of applied urea‐N. Two field 15N balance studies at multiple rates of urea with and without a urease inhibitor, phenyl phosphorodiamidate, were conducted in the Philippines. The urea was split broadcast into floodwater at 16 or 18 d after transplanting and at 5 to 10 d after panicle initiation. The applied urea‐15N not recovered in the rice and soil at crop maturity was assumed to represent total gaseous N loss and hence the potential savings in urea‐N that could be obtained with the use of an inhibitor that completely eliminated gaseous N loss. The potential savings in urea‐N consistently increased with increasing N rate. In 1985. the potential urea‐N savings were 17, 23, and 29% at 30, 60, and 120 kg N ha−1, respectively. In 1986, they were 13, 34, and 37% at 40,80, and 120 kg N ha−1, respectively. In each experiment, there was a significant quadratic response in grain yield to applied N. Models were developed for observed responses to applied urea and for potential yield responses to urea assuming complete elimination of gaseous N loss with no effect on rice other than increasing the availability of fertilizer‐N. Elimination of gaseous N loss could have increased grain yield by a maximum of 6 and 8% in 1985 and 1986. respectively. These percentages corresponded to 0.4 and 0.5 Mg ha−1 increases in grain yield, respectively.
Relating Calculated Leaf Area Index, Evapotranspiration, and Irrigation Method of Sugarcane
Authors: Shih S. F.
Published: July 2010

The determination of the considerable amount of water used in south Florida for crop production has been time‐consuming and expensive. The Standard Class A National Weather Service pan evaporation (SPE) has been used to estimate evapotranspiration (ET), but requires crop coefficients, ET/SPE, which vary with plant development stage, season, leaf area index (LAI), yield, and irrigation method. The objective of this study was to establish relationships among ET, SPE, LAI, yield of plant and two ratoon crops of sugarcane (Saccharum spp.), and two irrigation methods. Lysimeters were used for 3 yr (1980‐1982) on a Boca fine sand (loamy, siliceous, hyperthermic Arenic Ochraqualfs). Irrigation methods were drip irrigation and subirrigation systems. Total crop seasonal ET values were 1322 mm for drip irrigation, and 1275 mm for subirrigation. The sugarcane average yield under drip irrigation (143 t/ha) was significantly higher than that under subirrigation (119 t/ha), and was linearly related to the ET. The crop coefficient is curvilinearly related to the LAI. The relationship of ET/SPE to LAI was: 0.649 + 0.185 LAI − 0.025 LAI2 (R2 = 0.77) for both irrigation methods. The relationship of ET/SPE to LAI of the second ratoon under subirrigation was: 0.599 + 0.089 LAI − 0.011 LAI2 (R2 = 0.87).
Water‐Stress Effects on Alfalfa Forage Quality After Adjustment for Maturity Differences
Authors: Halim R. A. , Buxton D. R. , Hattendorf M. J. , Carlson R. E.
Published: July 2010

Forage quality of alfalfa (Medicago sativa L.) often is higher in water‐deficit‐stressed plants than in nonstressed plants. At least part of the improvement could result from a delay in plant development due to the water stress. The objective of this study was to determine forage quality response of alfalfa to water stress and to relate this to corresponding changes in plant maturity, phonological development, and growth. ‘Apollo II’ alfalfa was grown in 100‐L containers set into the ground and protected by a movable rain shelter. Plants were watered either weekly or twice weekly to 112,100, 88, 76, and 64% of field capacity during 2 yr. Regrowth herbage was harvested at five weekly intervals beginning 3 wk after the initial cut. Plants were divided into stem bases (portion of stems below and including the sixth node), stem tops, and leaves before forage quality analyses were conducted. Plant maturity decreased linearly with increasing water stress. Averaged over the harvests, leaf‐to‐stem ratio (LSR) increased from 0.60 in the well‐watered treatments to 0.72 in the most severely stressed treatment. Delayed plant maturity and node number did not account fully for the increase in LSR under water stress. In vitro digestible dry matter (IVDDM) in stems, which increased by about 9% under water stress, was largely accounted for by delayed plant maturity. In stem bases, crude protein (CP) concentration increased by 11% with increasing water stress, even after accounting for differences in plant maturity. Cellulose concentration, expressed on a cell‐wall (CW) basis, decreased whereas CW hemicellulose concentration increased with water stress in both leaves and stems, and these changes were not entirely attributable to differences in plant maturity and growth. Thus, the slowing of plant maturation and growth during water stress accounted for much, but not all, of the changes in forage quality.
Predicting Superior Yielding Spring Wheat and Oat Cultivars using Past Yield Data
Authors: Gellner J. L.
Published: July 2010

Agronomists use data from yield trials when recommending the greater yielding (top‐yielding) cultivars of spring wheat (Triticum aestivum L.) and oat (Avena saliva L.) to growers. At most land grant universities, cultivar recommendations are based on 3‐yr yield means. It is not clear, however, that this procedure is the best predictor of top‐yielding cultivars in the subsequent year. Using South Dakota cultivar performance testing data, eight different yield means were derived from various combinations of previous years' yield data. These eight predictors were assessed for their ability to identify the five top‐yielding cultivars in the subsequent year. Mean yield data were used from 1972 to 1987 for six and five locations for spring wheat and oat, respectively. The eight predictors were compared for differences in mean number of top‐yielding cultivars identified with Friedman rank sum two‐way analysis of variance. Also, predictors were compared to the expected mean number of top‐yielding cultivars identified if cultivar selection was random. The effectiveness of prediction from yield trials with varying coefficient of variation or least significant difference values was assessed. When averaged across all locations, selecting cultivars by mean yields using only the previous year, or using all yield data available for each cultivar, identified the largest number of top‐yielding cultivars in the subsequent year. These predictors were also superior to random selection in one of 11 locations. For oat, prediction was better from yield trials with CV values below 10.7 or LSD values below 8.7. For this data set, cultivar recommendations based on fewer than 3‐yr yield data were equally effective at predicting top‐yielding cultivars as those using 3 yr of yield data.