bluuebunny/crossref_metadata_2025 huggingface dataset:
Yield and Quality of Birdsfoot Trefoil Stockpiled for Summer Utilization1
Authors: Collins Michael
Published: July 2010

Pasture production is generally lower during summer than during spring and autumn in the midwestern and eastern states of the USA. Forage stockpiled during spring could increase the carrying capacity of pastures during summer. The objective of this experiment was to study the use of birdsfoot trefoil (Lotus corniculatus L.) to provide stockpiled forage for utilization during summer.

Small plots (1.5 ✕ 5.8 m) of ‘Empire’ birdsfoot trefoil on Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudoll) were managed according to eight cutting treatments (T) in 1979 and 10 treatments in 1980. Harvest dates in 1979 were; (T1) 30 May, 16 July, and 10 October, (T2) 30 May, 1 August, and 10 October, (T3) 30 May, 15 August, and 10 October, (T4) 28 June, 16 July, and 10 October, (T5) 28 June, 1 August, and 10 October, (T6) 28 June, 15 August, and 10 October, (T7) 30 May, 28 June, 1 August, and 10 October, and (T8) 30 May, 28 June, 15 August, and 10 October. Harvest dates in 1980 were: (T1) 28 May, 14 July, and 17 October, (T2) 28 May, 1 August, and 17 October, (T3) 28 May, 15 August, and 17 October, (T4) 13 June, 14 July, and 17 October, (T5) 13 June, 1 August, and 17 October, (T6) 13 June, 15 August, and 17 October, (T7) 28 May, 25 June, 1 August, and 17 October, (T8) 28 May, 25 June, 15 August, and 17 October, (T9) 14 July and 17 October, and (T10) 1 August and 17 October.

Total seasonal matter yield was greatest in 1979 for plots left unharvested between late May and mid‐July (T1, 5.9 metric tons/ha). An additional treatment in 1980 in which forage was left unharvested through the spring and harvested in early or mid‐August (T9 and T10) produced yields similar to that from T2, T3, T6, and T8. Stockpiling after mid or late June (T4 to T6) instead of late May (T1 to T3) reduced mid‐summer yields by approximately 50% in both years. Averaged over the 2 years, forage stockpiled from late May until early August (T2) averaged 62.8% in vitro dry matter disappearance (IVDMD) and 2.34% N. Birdsfoot trefoil stockpiled all spring and harvested in early August in 1981 (T10) had an IVDMD of 56.4 and 1.96% N. Shorter stockpiling periods resulted in higher IVDMD and lower acid detergent fiber (ADF) and neutral detergent fiber (NDF) concentrations in the harvested forage, but also resulted in lower yields of stockpiled forage. These results indicate that birdsfoot trefoil can be managed to provide forage for summer use and that the length of the stockpiling period does influence both the yield and the composition of forage produced. The optimum management is dependent on the quality of forage required for a particular class of livestock.
Kentucky Bluegrass Tolerance to Consecutive Preemergence Herbicide Treatments1
Authors: Johnson B. J.
Published: July 2010

Herbicides are one of several management practices necessary to maintain good quality, weed‐free turf. To be acceptable, they must control weeds without causing turfgrass injury. An experiment was conducted on Congaree loam (Fluventic Dystrochrepts) in the mountain region of Georgia to determine the effects of consecutive annual herbicide treatments on six Kentucky bluegrass (Poa pratensis L.) cultivars.

Standard rates of DCPA (dimethyl tetrachloroterephthalate), bensulide [O,O‐diisopropyl phosphorodithioate S‐ester with N‐(2‐mercaptoethyl) benzenesulfonamide], benefin (N‐butyl‐N‐ethyl‐a,a,a‐trifluoro‐2,6‐dinitro‐p‐toluidine), or oxadiazon [2‐tert‐butyl‐4‐(2,4‐dichloro‐5‐isopropoxyphenyl)−Δ2−1 ,3,4‐oxadiazolin‐5‐one] affected the quality and stand of Kentucky bluegrass cultivars very little. However, oxadiazon applied at the 3X rate reduced the quality of all cultivars in early spring and the stands of ‘Victa’, ‘Merion’, and ‘common’ in late summer when compared with bensulide. Benefin applied at the 3X rate reduced the quality of ‘Adelphi’, ‘Vantage’, Victa, and ‘Fylking’, but not stand when compared with the recommended benefin treatment. Neither napropamide [2‐(a‐naphthoxy)‐N,N‐diethylpropionamide] or prosulfalin {N‐[[4‐(dipropylamino)‐3,5‐dinitrophenyl]sulfonyl]‐S‐S‐dimethylsulfilimine} should be applied to Kentucky bluegrass cultivars because of severe injury.
Relative Efficiency of Applied N and Soil Nitrate for Winter Wheat Production1
Authors: Haby V. A. , Simons C. , Stauber M. S. , Lund R. , Kresge P. O.
Published: July 2010

The fertilizer N recommendation for a given yield of dryland winter wheat (Triticum aestivum L.) is lowered by the amount of nitrate‐nitrogen (NO3‐N) measured in the upper 1.2 m soil profile. This implies that soil NO3‐N substitutes for fertilizer N on an equal basis. The study was designed to compare the effectiveness of soil NO3‐N in the 1.2 m depth with fertilizer N for wheat production. Data were from 19 siteyears of N, P, and K rate combinations in 23 treatments planned to fit the nested‐cube statistical design. A response function for grain yield was estimated using fertilizer N, P, and K, soil NO3‐N, P, and water plus seasonal (April‐July) precipitation in a nonlinear regression model. All explanatory variables except fertilizer N and soil NO3‐N were set at fixed values to derive the yield response function. Marginal rates of substitution (MRS) of soil NO3‐N for fertilizer N were derived from representative yield levels. Results indicate that soil NO3‐N in the 1.2 m surface depth is not as efficient (approximately one‐third) as fertilizer N for grain production. Substantial differences in economic returns exist between comparisons of fertilizer recommendations made using the response surface vs an accepted one‐to‐one substitution. Differences are greatest in the range of 75 to 150 kg of soil NO3‐N/ha; the maximum difference, $44.36/ha occurs at a NO3‐N level of 100 kg/ha. Additional research is needed on the N supplying ability of soil NO3‐N for plant growth based on its zones of concentration within the soil profile.
Semiautomated X‐Y‐Plotter‐Based Method for Measuring Root Lenghts1
Authors: Wilhelm W. W. , Norman J. M. , Newell R. L.
Published: July 2010

Root‐length measurements are an important aspect of many agronomic research programs. Several automated systems have been reported which use modifications of the line‐intersect technique to estimate root length; however, most of these systems are very costly. This paper describes an inexpensive automated system using a modified line‐intersect technique to estimate root length. An X‐Y plotter was used to move a light sensor in a grid pattern through the projected photographic image of a root system, recording intersections with an event counter. Compared to manual counting using the line‐intersect technique, the system described accurately estimated root length of samples up to 10 m in length (r2 = 0.98). The advantage of our system is that costs are reduced by using equipment that is readily available at most laboratories: X‐Y plotter and slide projector. The cost of additional items was less than $600. Each determination of root length required 50 sec. The accuracy of the system was comparable to others that are based on the line‐intersect technique.
Foliar Fertilization of Soybeans. II. Effect of Biuret and Application Time of Day1
Authors: Poole W. D. , Randall G. W. , Ham G. E.
Published: July 2010

Negative yield results from the foliar application of NPKS solutions to soybeans [Glycine max (L.) Merr.] at the podfilling stage have been reported recently. Many of these studies have cited phytotoxicity and leaf burn as a causal factor. The purpose of this study was to investigate two factors which may contribute to these yield decreases: (1) biuret in the urea and (2) time of day of application. Biuret, a contaminant in fertilizer‐grade urea, was added to a base NPKS solution containing biuret‐free urea at the rates of 0, 0.25, 0.50, 1.0, 2.0, and 4.0% of the weight of the urea in the fertilizer material. Application of the biuret containing fertilizer solutions either one or three times did not reduce soybean yield and seed weights at three sites in the 2 study years. To determine the effect of application time of day, an NPKS solution containing 24 + 2.4 + 7.2 + 1.2 kg N + P + K + S/ha was applied to soybeans at 0300, 0600, 0900, 1200, 1500, 1800, 2100, and 2400 hours four times at 7 to 10 day intervals during podfilling. Under the climatic conditions encountered in the 2 years of this study, soybean yields were not significantly (P=O.lO level) affected by the time of application. However, consistent trends toward lower yields with midday applications allow us to suggest that the application of foliar fertilizer before 0800 or after 1700 hours will minimize chances of foliar injury and may improve chances of a positive response.
Seasonal Zn, Cu, Mn, and Fe Levels of Western Wheatgrass and Green Needlegrass as Affected by N Fertilization1
Authors: Halvorson A. D. , White L. M.
Published: July 2010

Nitrogen fertilization has been used to increase forage production of range grasses in the northern Great Plains; however, little information is available as to how N fertilization affects minor element composition of range forage. Our objectives were to determine the effects of N fertilization on Zn, Cu, Fe, and Mn concentrations in vegetative and floral tillers of western wheatgrass (Agropyron smithii Rydh.) and green needlegrass (Stipa viridula Trin.) throughout the growing season. Nitrogen fertilizer (0,40,80,160,320, and 640 kg N/ha) was applied in a completely randomized design to each grass species growing on a calcareous silt loam (Typic Haploborolls). Plants were collected on 10 and 11 sampling dates in 1973 and 1974, respectively. Nitrogen fertilization significantly increased the level of Zn, Cu, and Mn in green needlegrass and Zn and Mn in western wheatgrass forage. Absolute changes in mineral composition caused by N fertilization were very small and of little practical significance. Forage Zn and Cu levels declined throughout the growing season and were generally below recommended allowances (less than 20 to 30 πg/g Zn and 4 πg/g Cu) for proper cattle nutrition by mid‐June. Therefore, supplemental Zn and Cu may be required in diets of cattle being fed or grazing western wheatgrass or green needlegrass grown in the northern Great Plains after mid‐June. Forage Fe and Mn levels decreased as the growing season progressed until maximum forage yield was reached in June. Iron then started accumulating in the forage while Mn remained relatively constant during the remainder of the growing season. Iron (>80 πg/g) and Mn (>35 πg/g) were well above the recommended minimum levels for proper cattle nutrition. Floral tillers of both grasses had lower concentrations of Zn, Fe, Mn, and Cu than did vegetative tillers. In general, the earlier the harvest, the better the forage quality of western wheatgrass and green needlegrass will be with respect to Zn and Cu nutrition of cattle. Maintaining the grasses in the vegetative rather than floral growth stage would also improve forage quality
Wheat Development as Affected by Deficit, High Frequency Sprinkler Irrigation1
Authors: Hang An N. , Miller D. E.
Published: July 2010

An important limitation to wheat production worldwide is insufficient water. Therefore, it is important to know how the crop responds physiologically to water stress. The present study was conducted to determine the effect of various irrigation rates on wheat development. Variable irrigation treatments were initiated at pre‐ or early‐boot stage of Fielder spring and Nugaines winter wheat (Triticum aestivum L. em. Thell.) grown on sandy (mixed, mesic, Xeric Torripasamments) and loam (coarsesilty, mixed, mesic Xerollic Camborthids) soils. Different amounts of irrigation water were applied by the line source technique. Daily irrigation near the line source was equivalent to 1.00 (loam) or 1.15 (sand) times estimated evapotranspiration (ET). Pan evaporation (EP) was used to estimate ET as ET = 0.95 EP. On sandy soil, stress symptoms were first observed in plants receiving the least irrigation water (23 % estimated ET) 2 weeks after treatments were initiated. Symptoms included decreased number of green leaves, shorter plants, fewer heads, increased specific leaf weight and increased leaf‐stem dry weight ratios. Head growth rates were from 8.2 to 15.6 mg·head−1day−1, at the lowest and highest applications, respectively. Reproductive growth rate, crop growth rate, and partitioning to reproductive growth increased with increased irrigation. Effects of decreased irrigation were less on loam soil than on sandy soil. Stress symptoms did not appear until late in the growing season. There were significant differences in plant height, total plant weight, and head weight between the plots receiving highest and lowest irrigation rates (100 vs. 20 % estimated ET). Results indicate that normal growth and yield of wheat grown on sandy soil require irrigations that approach ET. However, on loam soil irrigation amounts can be decreased 40 to 50 % without affecting developing of plant parts.
Placement of Molybdenum Fertilizer in the Transplant Solution of Burley Tobacco1
Authors: Sims J. L. , Suchy M. E. , Cornelius P. L.
Published: July 2010

Two field experiments were conducted at Lexington, Ky. on Maury silt loam soil (fine, mixed, mesic Typic Paleudalf) to determine the effect of placing molybdenum (Mo) fertilizer as a solution in the root zone (band) at transplanting on growth, yield, and Mo concentration of burley tobacco (Nicotiana tabacum L. cv. KY 14). In one experiment on soil with initial pH of 5.5 that had received application of Mo in each of the 2 previous years, adding Mo as a transplant solution significantly increased plant Mo concentration, nitrate reductase activity, and cured leaf yields. Response to added Mo as a transplant solution was generally greater in plots previously amended with little or no Mo. This plant response to transplant applications is in contrast to previous studies showing little or no response to broadcast applications in soils of relatively low pH. In a second experiment on soil with pH of 6.2, plant Mo concentrations increased linearly as rate of Mo increased for both broadcast and transplant solution Mo applications. However, the slope of the regression line was greater for transplant Mo fertilization. The data indicate that Mo applied as a transplant solution is more effective than broadcast Mo. This will permit the use of lower rates when Mo is added at transplanting.
Effects of Increasing the Rates of Potassium and Nitrapyrin on Nitrogen Uptake by Corn1
Authors: Lueking M. A. , Johnson J. W. , Himes F. L.
Published: July 2010

Plant uptake of NH+4 is competitive with the uptake of K+. This relationship is of interest because fertilizer N is commonly applied in the NH+4 form and K is either present in large quantities in the soil or is applied as fertilizer. This study was conducted to determine the effects of high K rates and a nitrification inhibitor on the uptake of N and yields of corn (Zea mays L.). Corn (Landmark C747X) was grown in a field experiment during 2 years. Anhydrous ammonia was applied to all plots at 112 kg N/ha. Treatments consisted of three rates of KCI (0, 90, and 360 kg K/ha) applied in all combinations with three rates of nitrapyrin [2‐chloro‐6‐(trichloromethyl) pyridine] (0, 0.56, and 2.24 kg/ha) to a Kokomo silty clay loam soil (fine, mixed, mesic Typic Argiaquoll). Plant samples were taken 1 week after tasseling during one growing season for chemical analysis. Grain yields and N analyses of leaf tissue at harvest were averaged over 2 years. Soil samples were collected from the surface, 30 cm of soil surrounding the anhydrous ammonia band at 2‐week intervals for 12 weeks. The soil was analyzed for inorganic N to monitor the predominant ionic form available to the plants. Nitrapyrin application kept a higher concentration of NH+4 in the soil as compared to the checks for 4 to 6 weeks. Increased rates of K decreased yields and decreased the percent total N in leaves 6 through 10 at 12 weeks. Total N in grain was not affected by K rate or nitrapyrin rate, however, it was very low (0.95%) indicating an N deficiency in all treatments. Total nutrient analysis indicated that the concentration of Ca, Mg, Cu, and P decreased as K rate increased. The study indicated that increasing K rates may decrease yields if N is a limiting factor, due to a competition for uptake. The competition was confirmed by low total N in the grain and the decreased total N in leaves 6 through 10 at tasseling as K rate increased.
The “Ammoniator”: a Device to Enrich Waste Solutions with Nitrogen1
Authors: Huber D. M. , Karamesines P. D. , Nelson D. W.
Published: July 2010

Utilization of liquid wastes as fertilizers is sometimes limited by the large volumes (due to low N concentrations), which must be applied to provide optimum N rates for crops. A device (ammoniator) is described which facilitates the enrichment of waste slurries with anhydrous ammonia (or other concentrated liquid N sources) to improve the value of the wastes as nutrient sources for crop production. The ammoniator is inexpensive to construct, simple and safe to operate with ordinary precautions for NH3, use, and efficient in increasing the plant‐available N concentration in waste slurries two‐ to three‐fold. The device is adaptable for use in liquid manure tanker wagons or in pits and holding tanks.
Forage Residue Filtration, In Vitro Forage Digestion, and Elemental Solution Concentrations as Influenced by Soil Type and Concentration1
Authors: Cherney J. H. , Robinson D. L. , Ray D. J.
Published: July 2010

Ruminant animals may ingest large quantities of soil at certain times during the grazing season, but the effect of ingested soil on the mineral nutrition of ruminants is not clear. Our objectives were to determine the effects of soil on elemental concentrations in solution in an active in vitro system to estimate matter digestibility (IVDMD), rate and extent of cell wall digestion, and neutral detergent fiber (NDF) concentrations. Elemental concentrations were determined with an emission spectrophotometer immediately after the in vitro incubation of soil (0 to 300 g kg−1 forage) with annual ryegrass (Lolium multiflorum Lam.) for 6 to 48 h. The effect of soil on IVDMD was studied by adding three levels of soil (0, 75, and 150 g kg−1) to ryegrass samples prior to digestion. Four levels of soil (0, 100, 200, and 300 g kg−1) were combined with ryegrass samples to determine the effect of soil on NDF residue filtration. Increased soil levels in annual ryegrass forage samples resulted in linear increases in solution concentrations of Ca, Mg, Fe, Mn, and Zn, but no measurable Al or Ti in solution. Soil type had only small influences on Mg and Ca concentration in solution, with values ranging from 41.9 to 42.9 and 41.7 to 47.4 mg kg−1, respectively. Iron concentrations among soil types ranged from 0.93 to 1.81 mg kg−1, while Mn concentrations among soil types varied by nearly nine‐fold, from 0.25 to 2.24 mg kg−1. When soil was not present in the in vitro system, Ca, Mg, and Fe concentrations increased linearly with increased incubation time. However, solution concentrations of each of these elements responded differently to soil additions with increased incubation time. Soil had no apparent effect on the in vitro digestion process itself, but may lead to decreases in IVDMD values by interfering with filtration of sample residues. There was a linear increase in NDF values with increased soil additions to the forage samples, after correction with soil blanks. Neutral detergent fiber was significantly affected (P < 0.05) by filtration method, with mean values of 491 g kg−1 for sintered glass and 475 g kg−1 for glass wool plus sintered glass. The effect of soil contamination on forage quality analyses, resulting from inadequate filtration through sintered glass filters, cannot be overcome by expressing values on an ash‐free basis.
Effect of Crop Cover on Temperature Regime of an Alfisol in the Tropics1
Authors: Ghuman B.S. , Lal R.
Published: July 2010

Effect of maize (Zea mays L.) and cowpea (Vigna unguiculata L. Walp) canopies on the thermal regime of an Alfisol was investigated in flat and ridged seedbeds. An interaction was observed between canopy characteristics and soil moisture availability that influenced the soil temperature. When the soil moisture was >0.08 cm3 cm−3 (suction <0.64 bar), plants were protected against temporary wilting in the second half of the day and the 5‐cm soil temperature decreased with an increase of maize and cowpea canopies. However, when the soil moisture was ≤0.0.8 cm3 cm−3 (observed on 53rd day after seeding of crops in 1980), the 5‐cm maximum soil temperature under maize and cowpea crops was higher by 3 and 0.2°C, respectively, than in an uncropped flat seedbed, and by 7 and 3.9°C, respectively, than in uncropped ridges. The 5‐cm soil temperature under maize was slightly lower in the early growth stages than under cowpea irrespective of the method of seedbed preparation. However, the reverse was true towards the crop's maturity. In addition to percent ground cover, soil moisture deficit, and the possible change in thermal conductivity were responsible for this reversal in soil temperature observed at the maturity stage. Soil temperature regime is strongly influenced by the interaction between canopy cover and soil moisture regime, on the one hand, and canopy height and density and wind velocity, on the other. The effect of increasing crop canopy on soil temperature on a given day (that provided an identical radiation for all plots) was studied for the flat seedbed by staggering the seeding dates of crops in the first season of 1981. On the 16th June (at approximately 50,40, and 20 days after seeding), and when the crops were not under moisture stress, an increase of maize canopy from 0 to 59.7% decreased the soil temperature range from 10.6 to 4.3°C at 1 cm and from 3.2 to 1.6°C at 20 cm depth. Similarly, an increase of cowpea cover from 0 to 100% decreased the temperature range from 10.6 to 1.7°C at 1 cm and from 3.2 to 0.6°C at 20 cm depth. Empirical models were developed that describe the effects of canopy cover, soil moisture, and radiation on maximum and mean soil temperatures at 1, 5, and 20 cm depths.
Fertilizer Requirements for New Plantings of Tall Fescue and White Clover on Two Low‐Fertility Ultisols1
Authors: Burmester C. H. , Adams Fred
Published: July 2010

The use of optimum fertilizer rates is an essential component of managing pasture forages. Tall fescue (Festuca arundinacea Schreb.), the dominant cool‐season pasture grass in much of the South, is often interplanted with white clover (Trifolium repen L.) for improved forage quality and as an N source for the grass. Inadequate P and K fertilizers allow weeds to invade new plantings; too much N fertilizer allows tall fescue to choke‐out white clover. Since a paucity of data exists on N‐P‐K requirements for new plantings of fescue and fescue‐clover, two on‐farm experiments were established on soils that are typical of extensive pasture acreage. Three N rates (0, 67, and 134 kg ha−1), four P rates (0,15, 30, and 60 kg ha−1), and four K rates (0, 28, 56, and 112 kg ha−1) were applied to fescue and a fescue‐clover mixture; tall fescue alone received an additional N rate of 201 kg ha−1. Swards were clipped when 20 to 25 cm tall. Optimum N rate for tall fescue differed for the two sites; with clover in the sward, however, it was zero for both. Soil test P was very low for both soils (2 mg kg−1), and the optimum P rate for fescue was 15 kg ha−1 on one soil and 45 kg ha−1 on the other. With clover in the sward, optimum P rates were 50 to 55 kg ha−1 on both soils. Soil‐test K differed for each site (low vs. medium), but optimum K rate for fescue alone was 28 kg ha−1 for each soil; with clover in the sward, however, optimum K rate was higher on the soil with the lower soil K (110 vs. 28 kg ha−1). In fescue‐clover swards, weeds became dominant in the no‐P and no‐K plots at one site; tall fescue became dominant at the other. White clover almost disappeared in the no‐P and the highest‐N plots at both sites.
Root Observations Using A Video Recording System In Mini‐Rhizotrons1
Authors: Upchurch D. R. , Ritchie J. T.
Published: July 2010

To understand the development of a crop, information is needed concerning the dynamics of root growth and water uptake. An extendible, 13 mm diam borescope, a low light, monochrome video camera, and a video tape recorder were combined into a system for in situ root observation through 51 mm inside diam clear acrylic tubes installed at an angle 30° from vertical. The viewing area was illuminated by two fiber optic light guides and a variable intensity light source. The observation tubes could also be used as access for a neutron probe to measure water uptake and root growth at the same point. Sector intersections rather than line intersections were counted and used to convert observations from the mini‐rhizotrons to root length densities. A comparison of root length densities determined through mini‐rhizotrons, installed in four orientations with respect to plant rows, with those determined by soil sampling indicates there was a linear relationship between the two techniques. When only depths greater than 20 cm were used the correlation was higher than when all depths were included. Results indicated that no installation orientation was clearly the best when only the depths greater than 20 cm were included. Because of the variability of the results from individual mini‐rhizotrons the results from several tubes had to be averaged before there was a satisfactory correlation with the bulk soil root length density.
Quantification of Aspergillus flavus Growth on Inoculated Excised Kernels of Corn Genotypes1
Authors: Adams Nancy J. , Scott Gene E. , King Stanley B.
Published: July 2010

abstract

Corn (Zea mays L.) genotypes that resist invasion by Aspergillus flavusor inhibit toxin production would be one major approach to controlling aflatoxin contamination. The primary objective of this study was to determine if a particular laboratory technique could be used to detect differences in responses to A. flavusgrowth among maize genotypes. In addition, several other aspects were considered including a) effect of pollen source, b) kernel sample size, c) incubation period, d) surface sterilization of kernels, and e) stage of kernel development when sampled. Evaluation of corn genotypes involved the removal of kernels from ears of field‐grown hybrids at various times throughout the kernel development period. Kernels were placed on NaCl amended agar in petri dishes and inoculated with a suspension of A. flavusconidia. After incubation, samples were evaluated by recording the extent of A. flavusgrowth on each kernel. Significant genotypic differences were detected at all stages of kernel development sampled. However, these differences were not always consistent over sampling dates nor were they always consistent over years for a given sample date. Visual ratings of kernels sampled early in the kernel development period were higher than the ratings of those kernels sampled toward the end of the maturation process. Surface sterilized kernels promoted more A. flavusgrowth than did unsterilized kernels. Evaluation of F1, seed produced on inbreds revealed significant differences between reciprocal crosses. When a resistant inbred was used as the female parent, the seed gave a resistant response. However, when the susceptible parent was used as a female, A. flavusgrowth on inoculated kernels was markedly greater.
Water Condensation on Peltier‐Cooled Thermocouple Psychrometers: A Photographic Study1
Authors: Wiebe Herman H.
Published: July 2010

Water condensation on Peltier‐cooled thermocouple psychrometers (used to measure water potential) was observed and photographed under a microscope. Hundreds of minute droplets condensed on the entire junction within a second. As Peltier cooling continued these grew and coalesced, and after 1 min some 50 to 20 droplets uniformly covered the junction. After 5 min these had grown and merged into one (sometimes 2) large drop(s) that adhered to only part of the junction and to a lead wire. This drop grew by coalescence of the droplets that continued to condense on the junction until the drop eventually attained a constant diameter of about 0.3 mm, 6 times that of the junction. Evaporation during the psychrometric water potential measurement stage appeared uniform from the entire junction surface after short condensation times when it was covered with many small droplets. The two‐step procedure used to measure very low water potentials requires a large amount of condensed water. Poor psychrometric cooling is a hazard, however, if a drop only partly covers the junction after prolonged condensation times.
Physiological Responses to Sorghum Hybrids and Parental Lines to Soil Moisture Stress1
Authors: Hofmann W. C. , O'Neill M. K. , Dobrenz A. K.
Published: July 2010

The development of more drought‐resistant sorghum [Sorghum bicolor(L.) Moench.] germplasm depends on a fuller understanding of physiological responses to soil moisture stress. To investigate adaptation to moisture stress, physiological responses of six sorghum hybrids and their respective parental lines were evaluated under two irrigation treatments at Tucson, Ariz., in 1980 and 1981. The soil was a Comoro sandy‐loam (coarse‐loamy, mixed calcarious, thermic, Typic, Torrifluvent). Apparent photosynthesis, transpiration, diffusive resistance, and temperature differential (ambient temperature minus leaf temperature) were measured under field conditions at weekly intervals. Regression analysis was used to compare the physiological performance of the germplasm over a wide range of environmental conditions. Hybrid 4 was superior to its parental lines for all four physiological characteristics. In 1980, this hybrid was superior to the other hybrids in temperature differential (1.03°C) and transpiration (23.4 μg cm−2s−1) and had the highest mean apparent photosynthetic rates (45.9 mg dm−2h−1) and lowest mean diffusive resistance (1.41 cm s−1). Regression analysis is an effective tool that can be used for analyzing the physiological responses across diverse environmental conditions. By regressing the response of individual germplasm against the mean response of the population across all environmental conditions, the slope, mean, and coefficient of correlation were used to evaluate genotype‐environment interactions.
Use of Nitrogen Stress to Demonstrate the Effect of Yield Limiting Factors on the Yield Response of Soybean to Narrow Row Systems1
Authors: Cooper R. L. , Jeffers D. L.
Published: July 2010

Most research indicates yields of soybean [Glycine max(L.) Merr.] are increased as row width is narrowed and in general indicates that the optimum seeding rate per hectare increases. In spite of good management (appropriate seeding rates and good weed control), the anticipated yield increase from narrow rows is not always observed. It was postulated that this may be due to the effect of some other yield limiting factor or factors in the environment. In this study, N stress was used as a model to test this hypothesis. Three experiments were conducted to evaluate the effect of N stress on the yield advantage of a 17‐cm row system over a 75‐cm row system. In two of the experiments, a genetic non‐nodulated cultivar (‘Clark rj1,’) was compared with normal cultivars (‘Corsoy’ and ‘Williams’) in 17‐ and 75‐cm row widths across four rates (0, 55,110, and 220 kg ha−1) of added N. In the third study, a normal cultivar (‘Beeson’) was grown in similar narrow and wide row systems on soil (fine‐loamy, mixed, mesic Agric Fradgiudalf) with a low level of Rhizobium japonicum(Kirchner) Buchanan and four rates (0,8.8,17.6, and 26.4 kg ha−1) of granular R. japonicuminoculant were used. Results from all three studies dramatically demonstrated that the potential yield advantage (15 to 25%) of the 17‐cm row system over the 75‐cm row system was minimized or eliminated under N stress situations. These results corroborate other research results that indicate late season moisture stress has a similar effect and strongly supports the hypothesis that any yield limiting factor, such as lodging, moisture stress, N stress, or other nutrient stress can significantly reduce the yield response of soybean to a narrow row system. This relationship may help explain previously published data which appears to be contradictory, as well as some of the variability in yield response to narrow rows reported by soybean growers.
Influence of Selected White‐Rot Fungi and Topdressings on the Composition of Thatch Components of Four Turfgrasses1
Authors: Sartain J. B. , Volk B. G.
Published: July 2010

In a pot‐culture experiment with four highly‐thatched turfgrasses [bermudagrass, Cynodon dactylon(L.) Pers.; centipedegrass, Eremochloa ophiuroides; Kentucky bluegrass, Poa pratensisL.; and St. Augustinegrass, Stenotaphrum secundatum(Walt.) Kuntze] we examined the influence of selected white‐rot fungi and topdressings on the degradation of thatch components. Cores of each turfgrass were placed in pots and inoculated with one of four species of white‐rot fungi (Polyporous giganteus, Coriolus versicolor, Phebia gigantea, or Phanerochaete chrysosporium). Pots were reinoculated with the appropriate fungus 14 days after the initial inoculation and after the 6 month sampling. Subplot treatments of the split‐plot design were three topdressings (none, 0.31 cm sand, and 0.31 cm sand containing 4% colloidal phosphate). Samples of thatch were collected 6 and 12 months after inoculation and analyzed for cellulose and lignin by the acid detergent fiber procedure. Total oxidizable organic material and C and N were also determined. The cellulose content of bermudagrass and centipedegrass thatch was significantly reduced by Phebia gigantea, but no fungus significantly reduced the thatch cellulose content of St. Augustinegrass and Kentucky bluegrass. Coriolus versicolorsignificantly reduced the lignin content of thatch from all turfgrass species and the total oxidizable organic material of bermudagrass and centipedegrass. It appears to hold some potential for decomposing accumulated thatch. Topdressings with sand or a mixture of sand and colloidal phosphate significantly reduced the cellulose and lignin contents of thatch from most of the turfgrass species. Adding colloidal phosphate to the sand did not significantly increase the decomposition rate of the thatch. Kentucky bluegrass thatch contained the lowest quantity of lignin, and St. Augustinegrass thatch the least cellulose.
Row Pattern and Seeding Rate Effects on Value of Virginia‐Type Peanut1
Authors: Mozingo R. W. , Coffelt T. A.
Published: July 2010

The improvement of peanut (Arachis hypogaeaL.) productivity by genetics or management systems is a continuing process. The effects of cultivars, row patterns, and seeding rates on market value of virginia‐ type peanut were studied in a 2 ✕ 2 ✕ 2 factorial experiment for 4 years at the Tidewater Research and Continuing Education Center in Suffolk, Va. ‘Florigiant’ and ‘Virginia 81 Bunch’ (VA 81B) cultivars were seeded at the rate of 143 516 and 215 274 seed ha−1in single and double row patterns. Soil types were coarse‐loamy or fine‐loamy, silicious, thermic Aquic Hapludults (Nansemond fine sandy loam, 1977 and 1980, Nansemond loamy fine sand, 1979, and Eunola loamy fine sand, 1978). VA 81B had a higher percentage of extra large kernels, sound mature kernels, total meat, and market value ha−1than Florigiant. Florigiant produced a higher percentage of fancy size pods; however, no differences were found between cultivars for yield. The single row pattern was higher in percentage of fancy pods and total meat than the double row pattern. Seeding rate did not affect grades, however, the higher seeding rate had significantly higher yield and value ha–1. The cultivar X row pattern interaction was significant for yield and value. Row pattern did not affect yield and value of Florigiant, while both were higher for VA 81B in the double row system. This study indicated that peanut productivity can be increased by using the cv. VA 81B in the double row pattern, especially if used in combination with the high seeding rate.
Toxicity of Arrowleaf Clover Seed to Rhizobium trifolii1
Authors: Materon L.A. , Weaver R.W.
Published: July 2010

Arrowleaf clover (Trifolium vesiculosumSavi.) needs to be inoculated when sown in many fields in the southeastern USA. Survival of rhizobia on the seed following inoculation is critical for successful nodulation of the seedling. The effect the seed has on survival of the rhizobia has not been determined and may potentially be important to the success of inoculation. Seeds of subclover (T. subterruneumL.) and different genotypes of arrowleaf clover were placed on inoculated yeast mannitol agar medium to determine if the seed contained diffusable substances toxic to rhizobia. A thermostable, watersoluble diffusate was released from autoclaved and nonautoclaved seeds that inhibited the growth of many strains of Rhizobium trifolii. Seed‐coat disinfecting techniques that utilized aqueous solutions reduced toxicity of the seed and indicated that method of seed disinfection should be taken into consideration when conducting experiments on survival of rhizobia on seed. Two selections of ‘Amclo’ arrowleaf clover were demonstrated not to be toxic to R. trifolii. Additional research should be undertaken to identify the toxic substances in the seed and to determine their influence on survival of rhizobia applied to seed as an inoculant. The nontoxic seed would serve as a good control for such experiments and may prove to be useful to plant breeders in determining the genetic basis of the toxic substances.
Effects of N, Temperature, and Moisture Stress on the Growth and Physiology of Creeping Bentgrass and Response to Chelated Iron1
Authors: Schmidt R. E. , Snyder V.
Published: July 2010

Bentgrass (Agrostis palustris Huds.) turf often will improve in turf quality with applications of Fe during various times of the year in the transition zone even though soils contain sufficient levels of this trace element. In this study, 'Penncross' creeping bentgrass was grown in an environmental growth chamber in a factorial arrangement of three chelated Fe rates (iron diethylenetriamine pentaacetate, FeDTPA), two N levels, and three irrigation regimes. Turf was preconditioned to soil moisture stress by allowing soil moisture levels to dry to either 80,50, or 20% of the total unsaturated soil moisture (TUSM) before being irrigated to 100% TUSM. Ambient temperatures and photoperiods within the chamber were altered to simulate a late fall through mid‐summer growth cycle. Foliar applications of FeDTPA increased top growth during cool temperatures, but as temperatures were raised, FeDTPA applications depressed top growth. Net photosynthesis (NP) was also reduced by FeDTPA; however, dark respiration was unchanged. Foliar carbohydrates were increased with FeDTPA and appeared directly related to corresponding top growth reductions. Moisture stress preconditioning did not significantly influence plant response to applications of FeDTPA. However, repeated exposure to low soil moisture tended to reduce foilage yields and increase verdure. This indicated a more decumbent growth habit had resulted from repeated moisture stress. Net photosynthesis decreased as soil moisture levels declined. However, preconditioning turf to low soil moisture did not subsequently influence NP at either low or high soil moisture levels. Dark respiration (DR), was significantly lower for plants previously grown at the lowest irrigation regime regardless of subsequent soil moisture level. This reduction in DR may help account for the increased foliar carbohydrates associated with infrequent irrigation. This study did not show that turf response to FeDTPA was related to interactions with moisture stress. However, turf did adapt both morphologically and physiologically to repeated cycles of low soil moisture.
Cultivar, Nitrogen, and Soil Water Effects on Apex Development in Spring Wheat1
Authors: Frank A. B. , Bauer A.
Published: July 2010

A better understanding of the growth and yield determining traits of spring wheat (Triticum aestivum L.) is important to development of improved cultivars, management practices, and growth simulation models. The objectives of this research were to evaluate cultivars, soil water content, and fertilizer N with respect to development of the main stem apex under field conditions. The experiment was conducted over 4 years on a Williams loam soil (fine‐loamy, mixed Typic Argiborolls). Cultivars of hard red spring wheat and durum wheat (T. turgidum L.) averaged 17.6 and 20.2 days, respectively, from emergence to apex double‐ridge formation. Cultivars of hard red spring wheat also differed significantly in accumulated growing degree days (GDD) to double‐ridge formation. Plant growth stage at apex double ridge as determined by the Haun scale, differed among hard red spring wheat cultivars. In general, cultivars that had a longer vegetative apex development stage had a higher Haun score at double‐ridge formation and also higher grain yields. Apex development of the hard red spring wheat cvs. Olaf, James, and Alex grown with two fertilizer N levels and three soil water levels was affected more by cultivar than by soil water content or fertilizer N level. The seven‐leaf cv., James, compared with eight‐leaf cvs., Olaf and Alex, generally had a shorter duration apex vegetative growth stage and spikelet development stage, required fewer GDD to reach double‐ridge and terminal spikelet stages, and developed double‐ridges and terminal spikelets at a lower Haun score. Stepwise regression analyses indicated that differences in grain yield and spikes/plant at harvest could be partly explained by duration of apex development to double ridges and the terminal spikelet expressed in days, accumulted GDD, and Haun score. Yield and spikes per plant were also associated with the number of spikelets/spike.
Foliar Applications of Nutrients on Maize. II. Physiological Responses1
Authors: Below F. E. , Lambert R. J. , Hageman R. H.
Published: July 2010

Detailed analyses of plant and plant parts during the grain development period could establish mechanisms by which foliar fertilization, especially N, affects productivity of maize (Zea maysL.) hybrids. Field‐grown maize hybrids were sprayed at various stages of development with a mixture of nutrients (N‐P‐K‐S) in 1981 or urea in 1982 to determine whether foliar application of N would delay the remobilization of leaf N and leaf senescence thereby increasing productivity. In 1981, N‐P‐K‐S (12 kg N ha−1per treatment) was applied to plants of five hybrids at 7 days before and 12 days after anthesis. In 1982 urea (two equal applications for a total of 67 kg N ha−1) was applied to three hybrids B73 × Me17, Pioneer brand 3382, and Farm Services brand 854, at 12 and 6 days before anthesis and 9 and 15 and 25 and 32 days after anthesis to give treatments 1, 2, and 3, respectively. Soil type was Drummer silt loam (fine‐silty, mixed, mesic Typic Haplaquoll) in 1981 and a Flanigan silt loam (fine, montmorillonitic, mesic Aquic Arqiudoll) in 1982. The overall lack of effect of the fertilizer spray treatments on plant metabolism in 1981 was attributed to the small amount of supplemental nutrients applied. In 1982, changes in reduced N and nitrate of leaves, stalks, and whole plants were measured between anthesis and physiological maturity. These changes showed that the first urea treatment interfered with both nitrate uptake and assimilation for P3382 and assimilation for B73 × Mo17 and FS854. The second and third treatments had less effect on nitrate uptake and assimilation for all hybrids. The larger increases in stalk reduced N for all hybrids in response to the first urea treatment, compared to the second and third treatments, indicated that in the absence of a rapidly developing ear the stalk served as a storage reservoir for additional N. Urea applications caused no consistent increase, or alteration of the normal postanthesis decline, in the reduced‐N content of the leaves. The immediate decreases and trends in stalk carbohydrate contents show that the first two urea treatments interfered with the accumulation of carbohydrates, especially for P3382 and B73 × Mo l7. The observations that urea sprays did not increase N content of the leaves, decreased the accumulation of carbohydrates by the stalks, and appeared to interfere with indigenous N metabolism help explain the general ineffectiveness of foliar‐N treatments of maize.
Influence of Weed Control Treatments on Soybean Cultivars in an Oat‐Soybean Rotation1
Authors: Burnside Orvin C. , Moomaw Russell S.
Published: July 2010

Reduced tillage systems are being developed for the Great Plains that conserve limited moisture in order to improve soybean [Glycine max (L.) Merr.] cultivar response in this region. Fourteen soybean cultivars were grown in narrow rows using herbicides or tillage for weed control during the fallow period after oat (Avena sativa L.) harvest on an oat‐soybean rotation. Experiments were conducted at Concord, NE on a Colo silty clay loam (fine‐silty, mixed, mesic, Cumulic Haplaquolls) and at Lincoln on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic, Typic Argiudolls) during 1979 through 1982. The best broadleaf weed control occurred with ‘Gnome’, ‘Century’, ‘Weber’, and ‘Williams 79’ cultivars; also Gnome and Century had the best grass control as well as the lowest total weed yields. Early triazine injury was least (<30%) in Gnome, ‘Beeson 80’, ‘Elf’, ‘Wells II’, Weber, ‘Cumberland’, and Century. The highest yielding cultivars were ‘Mead’ and Century. Soybean cultivars generally yielded better on tilled vs. herbicide treated oat stubble, but the three cultivars showing the least difference in yields regardless of the prior fallow treatment were Cumberland, Beeson 80, and Weber. Cultivars selected for reduced tillage methods may differ from those used in conventional production systems.
Atrazine Tolerance in Warm‐Season Grass Seedlings1
Authors: Bahler C. C. , Vogel K. P. , Moser L. E.
Published: July 2010

Atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine] effectively controls many annual weeds in established warm‐season range grasses but can damage some of these grasses in the early seedling stage. This study determined the relative atrazine tolerance of seedlings of selected warm‐season grasses and evaluated the effectiveness of a greenhouse bioassay for seedling atrazine tolerance in range grasses. Seed of ‘Pathfinder’ switchgrass [Panicum virgatum L.], ‘Nebraska 54’ indiangrass [Sorghastrum nutans (L.) Nash], ‘Butte’ side‐oats grama [Bouteloua curtipedula (Michx.) Torr.], an experimental blue grama ‘PMK 1483’ [ B. gracilis (H.B.K.) Lag ex Steud], ‘Plains’ bluestem (Bothriochloa ischaemum var ischaemum (L.) Keng), ‘Caucasian’ bluestem [B. caucasica (Trin.) C.E. Hubbard] ‘Blaze’ little bluestem [Schizachyrium scoparium (Michx.) Nash], and a Nebraska experimental prairie sandreed [Calamovilfa longifolia (Hook) Scribn.] were planted in the greenhouse in a 1:1 soilsand mixture that contained 0,1,2, or 3 mg kg−1 atrazine. Seed lots from one cycle of field selection for atrazine tolerance of indiangrass and side‐oats grama were included. A field study was also conducted on a silty clay loam (Typic Argiudoll) and on a loamy sand (Udic Haplustoll) site using little bluestem, blue grama, prairie sandreed, Caucasian bluestem, and Plains bluestem. Survival ranking at 3 mg kg−1 atrazine, in the greenhouse, was: Caucasian bluestem = switchgrass > Plains bluestem > prairie sandreed > indiangrass (check) = indiangrass (cycle 1) > side‐oats grama (cycle 1) = side‐oats grama (check) = blue grama. Atrazine also reduced height in the surviving seedlings. Height reduction in did not appear to be related to seedling survival. Greenhouse data correlated closely with the loamy sand site. because the bioassay used a soil‐sand mixture. Excellent stands of Plains and Caucasian bluestem were obtained on the silty clay loam site at all atrazine rates. The bioassay was an effective screen to separate grasses with differing atrazine tolerances.