bluuebunny/crossref_metadata_2025 huggingface dataset:
Forage Dry Matter Accumulation and Quality of Turnip, Swede, Rape, Chinese Cabbage Hybrids, and Kale in the Eastern USA1
Authors: Jung G. A. , Byers R. A. , Panciera M. T. , Shaffer J. A.
Published: July 2010

Production of cool‐season (C3) herbage generally is low in summer and fall in the humid eastern USA. This study was conducted to determine the yields and pest problems of spring‐sown turnip, Brassica rapaL.; swede, B. napusL.; rape, B. napusL.; interspecific crosses between Chinese cabbage, B. campestris sensufaioL., and turnip or rape; or kale, B. oleraceaL., that were stockpiled. The crops were no‐till seeded (turnip and swede at 1.4 kg ha−1, rape, the hybrids, and kale at 4.2 kg ha−1) into mature alfalfa (Medicago sativaL.)‐grass stands. Prior to seeding, the sod was treated with isopropylamine salt of N‐(phosphonomethyl) glycine at 1.1 kg a.i. ha−1. The study was made in central Pennsylvania on Hagerstown silt loam (fine, mixed, mesic Typic Hapludalfs) soil in 1979 and 1980 and on Hublersburg silt loam (clayey, illitic, mesic Typic Hapludults) soil in 1981. Dry matter yield determinations were made sequentially at 30‐day intervals from 60 to 150 days post‐seeding. Fertilizer (P and K) was applied according to soil test results and 80 kg N ha−1was applied at seeding and 70 kg N ha−1between the 60‐ and 90‐day sampling dates. Three‐year mean dry matter yields for 13 of 19 cultivars exceeded 7.0 Mg ha−190 days post‐seeding. Yields plateaued from 80 to 160 days depending on plant species, cultivar, and year. Cultivar (across species) ✕ sampling date, turnip cultivar ✕ year, and swede, rape, and kale sampling date ✕ year interactions were significant for yield. Incidence of plant diseases was positively related to slowing of growth at physiological maturity. Some New Zealand turnip and rape cultivars were more resistant to flea beetle [Phyllotreta cruciferaeGoeze and P. striolata(Fab.)] than cultivars of European origin. Crude protein concentration of turnip and Chinese cabbage hybrid tops was higher at 120 than 90 days, but it was not for other species. Crude protein concentration ranged from 110 g kg−1in roots of certain cultivars to 270 g kg−1in turnip tops. Species ✕ sampling date and year ✕ sampling date interactions were significant for crude protein concentration and in vitro dry matter disappearance (IVDMD). The IVDMD values ranged from 800 to 930 g kg−1Kale had the lowest mean IVDMD, 840 g kg−1.
No‐Till Effects on Yield and Plant Density of Maize Hybrids1
Authors: Anderson E. L.
Published: July 2010

The use of no‐till practices for the culture of maize (Zea maysL.) is increasing because it reduces time, fuel, and labor requirements for land preparation. Studies have indicated that minimum tillage practices can slow maize growth and reduce plant stand density and grain yield. Little information is available on hybrid adaptation to these tillage systems. Field experiments were conducted to determine how grain yield and plant density (plants/ha) were affected by conventional (plowing followed by discing) vs. no‐till practices in commercial maize hybrids. Four locations in Maryland were used, including sites on the coastal plain (Typic Hapludult and Aquic Hapludult) and piedmont (Typic Hapludalf). The split‐plot experiment had tillage (conventional vs. no‐till) as the main plots and commercial maize hybrids, varying in cold tolerance and maturity, as the subplots. Six hybrids were grown in 1982 and 12 hybrids were grown in 1983 and 1984. The hybrid × tillage method interaction was not significant for plant density and was inconsequential for grain yield except at the Beltsville location. No one hybrid performed consistently better under conventional tillage. In 1982 tillage did not significantly affect grain yield; however, in 1983 grain yields for the no‐till practice were 17 to 24% greater than yields for conventional tillage at three of the four locations. In 1984 one location showed a 19% increase in yield under no‐till. Changes in plants/ha due to tillage ranged from a 22% decrease to a 4% increase under no‐till. The analysis of covariance between grain yield and plants per hectare indicated that there was no significant correlation between these parameters. These results indicated that selection for genetic traits to improve grain yield under no‐till practices may not be necessary for this geographical area. These commercial maize hybrids would produce similar amounts of grain under either tillage practice.
Emergence and Vigor of Soybean in Relation to Initial Seed Moisture and Soil Temperature1
Authors: Muendel H. ‐H.
Published: July 2010

This study was undertaken to assess the effects of initial seed moisture and of soil temperature on emergence and seed yield of soybean [Glycine max (L.) Merr.] in phytotron and field studies. Increasing the effective growing period would help in the establishment of soybean in more northern latitudes. Replicated lots of 100 seeds of two early maturing soybean entries, ‘Maple Presto’ and ‘King Grain X005’, were equilibrated to 6.6, 13.3, and 23.3% moisture levels. Phytotron studies involved day/night soil temperature regimes of 11.3/5.6, 16.7/10.7, and 20.5/14.l°C. Planting dates in the field were 22 May, 29 May, and 5 June 1979. Phytotron emergence exceeded 88% in all cases. Each 1°C decrease in mean soil temperature between 17.3 and 8.5°C resulted in a 2‐day delay of emergence. Emergence was independent of survival among different soil temperatures. Days to 80% emergence varied from 29 for the coolest temperature to 11 for the warmest in the phytotron and from 27 days for 22 May to 13 days for 5 June in the field. After 50% emergence, increasing differences were associated with differences in initial seed‐moisture contents. Maximum emergence took 1 to 2 days longer for the moistest than for the driest seeds. No differences were detected among lines for total emergence or for days to reach a certain level of emergence. No seed yield differences were associated with the initial seed‐moisture contents and planting dates, in spite of differential stands in the field. Equilibrating seed cannot be recommended. Using early maturing cultivars and seed lots with high germinability and seeding when soil temperatures are above 10°C are the recommendations for climatically marginal soybean areas such as southern Alberta.
Applied Nitrogen and Phosphorus Effects on Yield and Nutrient Uptake by High‐Energy Sorghum Produced for Grain and Biomass1
Authors: Hons F. M. , Moresco R. F. , Wiedenfeld R. P. , Cothren J. T.
Published: July 2010

Limited information is available concerning nutrient requirements of high‐energy sorghums (HES) (Sorghum bicolor L., Moench). The purpose of this study was to compare a HES, an intermediate grain cultivar (IGC), and a conventional grain cultivar (CGC) for grain and biomass (stover) yield, responses to applied N and P, and effects on nutrient partitioning and removal. Field experiments were conducted in 1983 and 1984 on Ships clay (Udic Chromustert) near College Station, TX. Nitrogen (0, 84,168 kg N ha−1) and P (0, 15, 30 kg P ha−1) were factorially applied to the three cultivars. Soil nutrient availability decreased after only one year of total dry matter harvesting and was reflected in greater responses to applied N and lower tissue nutrient concentrations and removals the second year. Cultivar and N influenced grain and biomass yields, while applied P had little effect on these parameters. The CGC and IGC produced more grain, but less biomass, than HES. The CGC removed the least nutrients in biomass and the most in grain, while removals by HES components were reversed. Although HES did yield more total dry matter, total crop N and P removals were similiar for all cultivars. HES did remove greater total quantities of all other nutrients. Applied N increased concentrations and uptake of most nutrients in grain and biomass.
Sorghum Yield and Soil Analysis from Sludge‐Amended Calcareous Iron‐Deficient Soil1
Authors: McCaslin B. D. , Davis J. G. , Cihacek L. , Schluter L. A.
Published: July 2010

Sorghum [Sorghum bicolor (L.) Moench] often becomes iron deficient when grown on calcareous iron‐deficient soils. Two experimental sites were selected with a history of severe iron chlorosis on sorghum to the point of plant death before maturity. Correcton of the Holloman soil (fine‐loamy, gypsic, thermic, shallow Typic Torriorthent) has not been practical with available treatments. A 5‐yr experiment consisting of sludge (89.6 Mg/ha) and dairy manure (89.6 Mg/ha), each applied the first year only, plus a fertilized check with N and P applied annually was conducted on one site. A 3‐yr experiment comparing two rates (33.6 and 67.2 Mg/ha) of sludge applied only the first year plus a fertilized check with N and P applied annually was conducted on the second site. Sludge was applied to half of each sludge plot the last year of each experiment to evaluate residual effects of sludge applied at the beginning. In both experiments, grain yields were low on the fertilized check plots and on the manure treatments after the first year. Sludge improved yields and soil test Fe levels, and corrected sorghum chlorosis throughout both experiments. For at least 5 yr following application, sludge also increased soil test levels of Zn and P.
Growth and Productivity of Four Corn Hybrids as Affected by Tillage1
Authors: Kaspar T. C. , Crosbie T. M. , Cruse R. M. , Erbach D. C. , Timmons D. R. , Potter K. N.
Published: July 2010

Conservation‐tillage systems produce different soil environments for corn (Zea mays L.) growth and development than do intensive tillage systems. Development of corn hybrids specifically adapted to conservation‐tillage environments may be one way to increase and stabilize grain yield. A 2‐yr field study on a Typic Haplaquolls near Ames, IA, with four hybrids and three tillage systems (no‐till, disk, and moldboard plow) was conducted to examine the effects of tillage systems, hybrids, and their interactions on shoot and root dry weights, leaf development, mature‐plant height, final plant stand, and grain yield. Moldboard plowing or disking increased vegetative growth relative to no‐till. Hybrids responded differently to the three tillage systems only during vegetative growth. Hybrids 2 and 3 had greater increases in shoot growth in response to moldboard plowing than to disking. Hybrid 3 also had a greater increase in root dry weight and leaf stage with moldboard plowing than with disking. Response to tillage for mature‐plant measurements differed between years but not between hybrids. No‐till plots had shorter mature plant heights (1.87 m) and lower grain yields (6.98 Mg ha−1) than moldboard‐plowed plots (1.96 m; 8.34 Mg ha−1) only in 1982. Grain moistures of no‐till plots averaged over years were 28 g kg−1 greater than those of moldboard‐plowed plots. Results of this study indicate that during vegetative growth, corn hybrids respond differently to tillage systems. Further evidence of hybrid ✕ tillage interactions, however, is needed to justify development of corn hybrids adapted to specific tillage systems.
Total Alkaloid Determinations in Larkspur and Lupine with near Infrared Reflectance Spectroscopy1
Authors: Clark D. H. , Ralphs M. H. , Lamb R. C.
Published: July 2010

Near infrared reflectance spectroscopy (NIRS) is used for quality component determinations in forages and grains. However, the use of NIRS to determine antiquality factors in forages has not been reported. Therefore, NIRS spectra were collected on leaf, stem, and head fractions to total 273 tall larkspur (Delphinium occidentale Muth.) and 246 velvet lupine (Lupinus leucophyllus Dougl.) samples. Total alkaloid concentrations (TAG) were determined through extraction and titration, and regressed against NIRS reflectance values from 1100 to 2500 nm. Three NIRS equations were developed to determine TAC: one each for larkspur and lupine, and one for a combination of larkspur and lupine. Of the total, 136 larkspur, 82 lupine, and 260 larkspur plus lupine samples were held from regression analysis and used for testing the equations. Standard errors of calibration for TAC were lowest for lupine, followed by larkspur and larkspur plus lupine (0.04, 0.10, and 0.10 dag kg−1, respectively). Standard errors of analysis for TAC were lowest for larkspur, followed by lupine and larkspur plus lupine (0.01, 0.05, and 0.10 dag kg−1, respectively). Relationships between NIRS and wet laboratory determined values were equal for larkspur and larkspur plus lupine (r2=0.93) and slightly lower for lupine (r2=0.90). Spectral comparisons of plant material and alkaloids showed strong relationships between the wavelengths used in the equations and alkaloid peaks. Total alkaloid concentrations in larkspur and lupine can be accurately analyzed by NIRS.
Planting Date Effects on Plant Growth and Development in Sesame1
Authors: Mulkey J. R. , Drawe H. J. , Elledge R. E.
Published: July 2010

Changes in the growth and development of the sesame (Sesamum indicum L.) plant induced by varying planting dates have not been fully studied. The purpose of this study was to evaluate the influence of three planting dates on plant growth and development in irrigated sesame. Field experiments were conducted in 1983 and 1984 on a Uvalde silty clay loam (fine, mixed, hyperthermic Aridic Calcuistall) soil. At maturity, stem dry matter was significantly higher for the 27 April and 15 May planting dates compared to 18 June. When planting was delayed from 27 April to 15 May or 18 June, the period of leaf growth and retention was reduced by 10.5 and 24.4%, respectively. Date of planting did not significantly affect total dry matter of reproductive parts, but percentage of mature seeds was reduced from 60.9% for the 27 April planting date to 53.6% for the 15 May, and 29.0% for the 18 June planted plots. Date of planting did not significantly affect height‐to‐the‐first‐capsule but did affect days‐to‐50%‐bloom, days‐to‐maturity, and seed yield. In 1983, days‐to‐50%‐bloom was reduced by 15 days, days‐to‐maturity by 26 days, and yield by 754 kg ha−1 when the planting date was delayed from 29 April to 20 June. In 1984, days‐to‐50%‐bloom was reduced by 10 days, days‐to‐maturity by 25 days, and yield by 1132 kg ha−1 when planting was delayed from 27 April to 18 June. Plant height and seed‐test‐weight were affected only in 1984.
Evaluation of Short‐Term Efficiency of Diammonium Phosphate versus Urea plus Single Superphosphate on a Calcareous Soil1
Authors: Lu D. Q. , Chien S. H. , Henao J. , Sompongse D.
Published: July 2010

Although research has been done on the fertilizer efficiency of diammonium phosphate (DAP) as a source of N or P, little information has been reported on its effectiveness as a dual source of N and P to plants. The objective of this study was to compare DAP with urea plus single superphosphate (SSP) as sources of fertilizer N and P on a calcareous clay soil (Typic Ustochrept). The influence of methods of fertilizer placement (surface broadcast, incorporation, and deep placement) on crop growth and nutrient uptake were investigated in a short‐term (6‐week) greenhouse evaluation using maize (Zea mays L.) as a test crop. Ammonia volatilization losses from both sources, when surface‐applied to the soil followed by daily water additions, were small, less than 6% of the applied N. Olsen P in the soil treated with urea + SSP was higher than the soil treated with DAP regardless of the method of fertilizer placement. Surface broadcasting apparently reduced the accessibility of P to the plant roots and resulted in a lower P uptake and plant yield than incorporation. Nitrogen uptake was as high with DAP as with urea + SSP when the fertilizers were either incorporated or deep‐placed. Surface application, however, resulted in lower N uptake from DAP than from urea + SSP. Both DAP and urea + SSP showed the same relationship in terms of P uptake as a function of Olsen P in the soil for a given method of fertilizer placement. The plant yields obtained with urea + SSP were higher than those obtained with DAP, regardless of the method of fertilizer placement.
Root Growth, Seedhead Production, and Quality of Annual Bluegrass as Affected by Mefluidide and a Wetting Agent1
Authors: Cooper R. J. , Henderlong P. R. , Street J. R. , Karnok K. J.
Published: July 2010

Annual bluegrass [Poa annua ssp. reptans (Hauskins) Timm.] often comprises a large portion of golf course greens, yet its shallow root system and extensive seedhead production limit its turf quality. The purpose of this investigation was to determine if annual bluegrass seedheads could be suppressed and rooting enhanced by the plant growth regulator mefluidide [N ‐(2,4‐dimethyl‐5‐{[(trifluoromethyl) sulfonyl]amino} phenyl)acetamide] and the wetting agent Aqua‐Gro (polyoxyethylene esters and ether of cyclic acid and alkylated phenols, silicone anti‐foam emulsion). Chemicals were applied prior to seedhead emergence during 1983 and 1984 to annual bluegrass grown in a rhizotron in fine quartz sand. Root elongation of mefluidide‐treated annual bluegrass was superior to the control for 2 to 4 weeks following Spring 1983 application. Maximum rooting depth of mefluidide‐treated turf was significantly greater than that of Aqua‐Gro‐treated or untreated turf during May 1983. Aqua‐Gro applied at either 4.2 or 8.4 L ha−1 generally did not affect rooting. In 1983, mefluidide (0.07 or 0.14 kg ha−1) prevented seedhead emergence throughout the entire seedhead production period (approximately 8 weeks) when applied under environmental conditions favoring uptake. Leaf tip yellowing occurred for 3 to 4 weeks following mefluidide application. Mefluidide‐treated turf, however, exhibited quality superior to untreated turf for approximately 6 weeks following discoloration. Aqua‐Gro provided little seedhead suppression and reduced quality for about 10 days following application. In 1984, environmental conditions were not conducive to chemical uptake so 1983 results were not corroborated. Mefluidide appears promising as an annual bluegrass management tool; however, more information is needed to determine the influence of environmental conditions on mefluidide uptake and its ability to suppress seedheads and enhance rooting at low rates.
Tolerance of Bentgrass to Dates and Frequency of Preemergence Herbicide Treatments1
Authors: Johnson B. J.
Published: July 2010

Creeping bentgrass (Agrostis palustris Huds.) use for golf greens is rapidly expanding in the South where heat and drought stress is higher for this species. To maintain a good quality weed‐free turfgrass, herbicides are often necessary. The purpose of this research was to determine the tolerance of ‘Penncross’ creeping bentgrass greens to herbicides applied on different dates and at different frequencies. Herbicides were applied in a randomized complete‐block design to artificial rootzone greens at two separate locations. Applications of oxadiazon {3‐[2,4‐dichloro‐5‐(1‐methylethoxy) penyl]‐5‐(1,1‐dimethylethyl)‐1,3,4‐oxadiazol‐2‐(3H)one}, bensulide [O,Obis(1‐methylethyl)S‐{2‐[(phenylsulfonyl)amino]ethyl}phosphoro‐dithioate] plus oxadiazon, and benefin [N‐butyl‐N‐ethyl‐2,6‐dinitro‐4‐(trifluoromethyl)benzenamine] plus oxadiazon caused slight to moderate bentgrass shoot discoloration, but the grass fully recovered with no stand loss during the year of treatment. In general, herbicides applied in early March did not discolor bentgrass as much as they did when applied in early April. There was no advantage in bentgrass tolerance with split applications at reduced rates when compared to a full single rate. In several instances, discoloration was higher from split applications (March and May or April and June) at reduced rates for oxadiazon and benefin plus oxadiazon than when the chemicals were applied as a single full rate (March or April). These studies show that oxadiazon alone or in combination with either bensulide or benefin can be used on Penncross creeping bentgrass if some foliage discoloration can be tolerated. Some injury may occur regardless of location and time of year.
Methods for Controlling pH in Hydroponic Culture of Winter Wheat Forage
Authors: Miyasaka S. C. , Checkai R. T. , Grunes D. L. , Norvell W. A.
Published: July 2010

Plants grown in hydroponic culture make useful experimental models for soil‐grown plants. However, a major problem of nutrient solution culture is the adequate buffering of solution pH. Four methods of controlling pH in hydroponic culture of winter wheat (Triticum aestivum L. ‘Centurk’) were compared at two levels of Ca (0.2 and 2.0 mM) to determine the buffering method with the least effect on the uptake of essential nutrient elements. These methods were: (i) manual titration with NaOH; (ii) Amberlite DP‐1 weakly acidic cation exchange resin loaded with Ca, Mg, K, and H; (iii) the organic buffer, 2‐(N‐morpholino)ethanesulfonic acid (MES), at 1mM; and (iv) MES a t 5 mM. Five‐millimolar MES gave the most consistent control of solution pH. However, it also inhibited Zn accumulation by wheat. One‐millimolar MES did not maintain the solution pH as well as 5 mM MES, but it did not significantly alter the uptake of any essential nutrient element. It is recommended as a pH buffer for the hydroponic culture of winter wheat. Resin in membrane bags did not adequately buffer the solution pH. It also removed some Mn and Zn from solution, thus depressing their uptake by wheat. Resin in a pump system adequately buffered the solution pH until its effectiveness was limited by the flow rate through the resin bed. Adequate buffering of solution pH was found to be critical for experiments that study the interactions between Ca and other nutrient elements. With the pH buffer, MES, the previously reported effects of Ca on depressing Mg, Mn, and Zn accumulation were observed. However, in the poorly buffered treatments, these elements tended to increase slightly with increasing Ca levels, perhaps due to the effect of Ca on maintaining root membrane integrity in an acidic environment.
Semidwarf and Conventional Height Sunflower Performance at Five Plant Populations
Authors: Majid Hashim R. , Schneiter A. A.
Published: July 2010

Semidwarf sunflower (Helianthus annuus L.) hybrids have been developed by several commercial companies and could be grown on large hectarage in the future. Information on the total water use and other agronomic traits of the semidwarf (SD) types as they compare to conventional or standard height (SH) sunflower is not available. This field study was conducted to: (i) determine total water use (TWU) and water use efficiency (WUE) of SD and SH sunflower, and (ii) determine the effect of plant population on harvest index (HI), stalk diameter, plant height, and leaf number of both plant types. Two experimental SD and two SH hybrids of similar maturity from the Cargill and Sigco Research breeding programs were grown at dryland populations of 32 123, 49 420, 66 717, 84 014, and 101 311 plants/ha over a 3‐yr period (1982‐1984) at Fargo, Carrington, and Prosper, ND. Data were collected and calculated for nine characteristics in this study. Total water use and WUE data were determined only at a plant population of 49 420 plants/ha. All hybrids evaluated had similar TWU, WUE, HI, and stalk diameter. The Cargill SH had the fewest number of leaves. It was concluded that reductions of plant height do not affect internode number, TWU, and HI. Other agronomic traits as a response to plant population were similar for both plant types, and observed differences were often due more to genotype origin than to plant type. Increasing plant population reduced HI, grain yield per plant, biomass per plant, and stalk diameter. Increasing plant population increased plant height of all hybrids except the Sigco SD.
Spring Wheat and Barley Responses to Ethephon
Authors: Simmons S. R. , Oelke E. A. , Wiersma J. V. , Lueschen W. E. , Warnes D. D.
Published: July 2010

Ethephon [(2‐chloroethyl) phosphonic acid] has recently been introduced in North America as a regulator to control lodging in cereals. A 3‐yr study (1983‐1985) was conducted to determine how widely grown spring wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) cultivars in the North Central United States responded to ethephon. Nine randomized complete‐block, split‐plot experiments with wheat, and seven with barley, were conducted at the Crookston (soil classification, Aeric Calciaquoll), Morris (Aeric Calciaquoll), St. Paul (Typic Hapludoll), and Waseca (Aquic Hapludoll) Experiment Stations in Minnesota. Ethephon was applied at a rate of 0.42 kg a.i. ha−1 in all years as well as 0.28 kg a.i. ha−1 in 1985. When lodging occurred, ethephon treatment at either rate lessened its severity. Ethephon shortened crop height, more so when applied at the higher rate. Effects of ethephon on grain yields varied from significant reductions (average 13% for wheat, 9% for barley) to significant increases (average 12% for wheat, 13% for barley). Increases were most common when control plots lodged, although higher yields in response to reduced lodging were not obligatory. When lodging did not occur, ethephon treatment tended to result in reduced yields. Among barley cultivars, ‘Robust’ was most likely to exhibit reduced yields. Genotypic variability for ethephon sensitivity among wheat cultivars was less evident. In most experiments, ethephon treatment lowered kernel numbers per spike or mass per kernel. We conclude that ethephon use is most reasonable when the production practices followed, or environmental conditions, assure the likelihood of significant lodging. Further research investigating cereal responses to lower ethephon rates, as well as interactions between ethephon and plant stress, is needed.
Random Stand Deficiency and Replanting Delay Effects on Soybean Yield, Yield Components, Canopy, and Morphological Responses
Authors: Willmot D. B. , Pepper G. E. , Nafziger E. D.
Published: July 2010

Poor soybean [Glycine max (L.) Merr.] emergence presents difficult replanting decisions. Most plant population research has involved deficient stands with even distribution rather than the more commonly encountered random gap distribution. The objective was to provide guidelines for making profitable replanting decisions. Field experiments were conducted in 1984 and 1985 to compare growth parameters and seed yield of an adapted cultivar in northern, central, and southern Illinois at 42,40, and 38° N Lat, respectively. Initial and delayed (21 d) plantings were made in rows 0.76 m apart. Two plant densities (291 550 and 202 350 plants ha−1) and five random stand deficiencies levels (0 to 60%) were established within each planting. The largest effect on seed yield was caused by random stand deficiency followed by environment and planting date. Stands with randomly imposed 0.31 m gaps totaling 40 and 60% of the plot areas resulted in 10.8 and 21.1% yield reductions, relative to uniform stands in the initial planting, respectively. Replanting delays resulted in an average relative yield loss of 9.0%. Photosynthetic photon flux density measurements were made when the initial planting reached R5 and were expressed as percent light interception (PLI). The PLI at R5 was not related to the 9.0% yield loss due to replanting delay. At the 60% stand reduction level the low plant density mean yield was 6.2% less than the high plant density mean over both plantings. Seed number per plant ranged from 63.9 in replanted full stands to 195.1 in the most deficient initial planted stands. Seed weight effects were minimal and inconsistent. The PLI decreased quadratically with increasing stand reductions from 92.5% in full stands to 80.4% in stands reduced by 60% (over all other factors). Relative yield (RY) was regressed on PLI as follows: (i) initial planting: RY = 39.65 + 1.4781 PLI (r2 = 0.941, P < 0.01); and (ii) Delayed replanting: RY = 47.75 + 1.4598 PLI (r2 = 0.944 P < 0.01). In most environments only stand reductions of over 50% could be justifiably replanted. The results provide guidelines for decisions of whether or not to replant, based on expected yield losses due to irregular initial stand emergence compared with expected losses due to replanting delay.
Simulation of Maize Phenology
Authors: Grant R. F.
Published: July 2010

In order to perform reliably, crop simulation models require an accurate treatment of crop phenology. A procedure for simulating maize (Zea mays L.) phenology was developed as a subroutine for a maize growth model which ran on an hourly time step. Maize development is simulated from hourly rates of leaf initiation and appearance during three phases of organ differentiation: juvenile, inductive, and reproductive. Leaf initiation occurs during the first two phases, and is terminated by tassel initiation, at which time final leaf number is established. The timing of tassel initiation during the inductive phase is determined by photoperiod and temperature effects on leaf number. The reproductive phase begins at tassel initiation and ends at silking shortly after the appearance of the last leaf before the tassel. Functions used to calculate leaf numbers and rates of leaf initiation and appearance are taken from published results of phytotron studies. Model estimates of leaf number, and of dates of tassel initiation and silking were compared with those observed from a maize phenology trial conducted at five sites in North America. Estimated dates of silking were also compared with those from other data sets. Estimated leaf numbers were usually within one of those observed at all but one site in the phenology trial, where leaf numbers were overestimated by as much as four leaves. Estimated dates of tassel initiation and silking were usually within 5 d of observed dates except at the warmer sites in Texas where estimated dates preceded observed dates by 5 to 15 d. The data suggest that high temperature acclimation may have resulted in slower rates of development than those predicted at some of the warmer sites. Chilling, acclimation, and other effects on phenology not present in phytotron studies will have to be considered further before the results of these studies may be widely used in models of maize phenology.
Yield, Dinitrogen Fixation, and Aboveground Nitrogen Balance of Irrigated White Lupin in a Mediterranean Climate
Authors: Larson K. J. , Cassman K. G. , Phillips D. A.
Published: July 2010

As an initial effort to evaluate irrigated white lupin (Lupinus albus L.) in California, we evaluated seed yield, N2 fixation, and the N economy of this crop in a 2‐yr field study. Treatments were arranged in a completely randomized block design and included two (Year 1) or three (Year 2) lupin cultivars each either (i) inoculated with Bradyrhizobium sp. (Lupinus) and no N fertilization, (ii) with neither inoculation nor N fertilization, or (iii) with N applied at 200 kg N ha−1 (Year 1) or 275 kg N ha−1 (Year 2). Mean seed yield from inoculated treatments was 5.73 Mg ha−1 with 46.4 g N kg−1 in Year 1, and 4.79 Mg ha−1 with 48.9 g N kg−1 in Year 2. Seed yield was similar with or without inoculation, but total dry matter and N accumulation were highest in inoculated treatments. Nitrogen fertilization did not increase yield or N accumulation above that of inoculated treatments. Estimates of N2 fixation by the N difference method ranged from 193 to 247 kg ha−1. Symbiotically fixed N represented 67 to 78% of total aboveground plant N, but the N harvest index ranged from 0.80 to 0.91, and thus, total seed N exceeded the quantity of N2 fixed by 23 to 68 kg N ha−1. Despite the lack of a net increase in soil N after seed removal, the yield potential and N2 fixation exhibited by white lupin during the cool‐season are favorable attributes for a winter annual protein crop in a mediterranean climate.
Cotton Canopy and Drying Effects on Runoff During Irrigation with Moving Sprinkler Systems
Authors: Ben‐Hur M. , Plaut Z. , Shainberg I. , Meiri A. , Agassi M.
Published: July 2010

Self‐propelled moving sprinkler irrigation systems (MSIS) have become increasingly popular in recent years. However, high amounts of runoff were measured from fields during irrigation with MSIS. Surface runoff from a silt loam loess soil (Calcic Haploxeralf) and a clay vertisol soil (Typic Chromoxerert) under different irrigation management was studied in field plots (3 m2, with a slope of about 2%). The experimental fields were irrigated with a lateral MSIS (spray nozzle) with a discharge of 650 L m−1 h−1 and an average water application rate of about 100 mm h−1. The percent surface runoff in loess and vertisol soils was 22 and 0%, respectively, under straw mulch conditions vs. 53 and 39% under unmulched conditions. The greater runoff was due mainly to crust formation at the soil surface. The impact energy of the irrigation water drops caused the soil surface structure to break down and form a surface crust with a resultant decrease in the infiltration rate (IR). Coverage of the loess‐crusted soil surface by the cotton (Gossypium hirsutum L., cv. Acala SJ‐2) canopy did not reduce the percent runoff from weekly irrigations of 50 mm. A drying period of 7 d between water applications did not break the crust, which was formed at the beginning of the irrigation season, and the large amount of runoff (50%) remained constant until the end of the season. Conversely, 14 to 18 d of drying caused a breakage of the crust, resulting in increased IR. Under these conditions, the cotton canopy prevented the reformation of the crust during consecutive irrigations and the runoff decreased to 15% at the end of the season. When the amount of water per irrigation was 15 to 30 mm and the drying period was 2 to 3 d, the runoff value was about 20%. This low percentage apparently resulted from insufficient amounts of water necessary to form a fully developed crust.
Serological Distribution of Bradyrhizobium japonicum from U.S. Soybean Production Areas
Authors: Weber D. F. , Keyser H. H. , Uratsu S. L.
Published: July 2010

Bradyrhizobium japonicum strains are widely distributed throughout U.S. soybean [Glycine max (L.) Merr.] production areas. Many surveys of local or regional areas have been conducted, but none has covered all production states or related their distribution to strains previously used in commercial inoculants. A total of 767 isolates of root nodule bacteria, from 79 locations in 27 states of the major soybean production areas, were analyzed with 15 antisera to determine serological composition. Eight serogroups represented 63% of the isolates, 19% of the isolates had double reactions, and 15% did not react. The predominant serogroup was 123, which represented 24% of the isolates tested, followed by serogroup 31 with 14%. The other isolates were evenly distributed among serogroups. The relationship between the pattern of distribution of the isolates around the USA and strains used in commercial inoculants is discussed. Knowledge of isolates that constitute an indigenous Bradyrhizobium population should be helpful in selecting more effective strains for inoculants.
Sample Intensity and Timing for Detecting Acremonium coenophialum Incidence in Tall Fescue Pastures
Authors: Thompson R. W. , Fribourg H. A. , Reddick B. B.
Published: July 2010

Pastures of tall fescue (Festuca arundinacea Schreb.) infected with the endophytic fungus Acremonium coenophialum Morgan‐Jones and Gams have been associated with livestock disorders known collectively as fescue toxicosis. Destruction of infected (E+) fescue pastures and reestablishment with endophyte free (E−) seed is beneficial for eliminating fescue toxicosis. However, since management decisions must be based on knowledge of A. coenophialum incidence, sampling of pastures should provide information about fungal incidence with accuracy. Two experiments were conducted to compare sampling methods. In the fist experiment, eight 4‐ha, 2‐yr‐old pastures established with seed mixtures ranging from near 0 to more than 70% E+ were sampled. A transect method and a stratified random sample based on area at an intensity of 23 tillers ha−1 were used. In the second experiment, four 20‐yr‐old, 2‐ha E+ pastures were sampled at monthly intervals for 2 yr. Stratified random sampling at 41 samples ha−1 and simulated transects using the same data were used. Samples were assessed for E+ status using Protein A enzyme‐linked immunosorbent assay (PAS‐ELISA). In the first study, observed E+ incidence in two pastures increased from 15 or 30% to about 60%, respectively, during the 2‐yr. Reasons for this increase are not known. The other pastures, established with 0,45, 60, and 75% E+ seed had only small increases in E+ incidence. Significant E+ incidence could be detected in the second study at any time during the year. Six to eight samples ha−1 were adequate for characterizing A. coenophialum status. Transect and stratified random samplings gave similar E+ estimates.
Trend Analysis to Improve Efficiency of Agronomic Trials in Flue‐Cured Tobacco
Authors: Bowman D. T.
Published: July 2010

The desire to improve statistical evaluation efficiency in flue‐cured tobacco (Nicotiana tabacum L.) cultivar trials and the inconvenience of restricted entry numbers in incomplete block designs prompted an investigation into a statistical procedure known as the trend analysis. The objective was to determine relative efficiency of the trend procedure compared to the randomized, complete block design by examining error variances from both analyses of variance. Eleven traits on all entries of the North Carolina Official Flue‐Cured Tobacco Variety Trials were examined at five environments. Relative efficiency of trend compared to the randomized, complete block design ranged from 97 to 161% for traits and environments. Only one trait, number of ground suckers, showed no improvement in precision (101%) from trend analysis while quality indicators ($/kg and grade index) showed the greatest improvement (126 and 124%) when averaged for all environments. The data revealed that blocking may be effective for one trait and not another.
Allelopathy of Crop Residues Influences Corn Seed Germination and Early Growth
Authors: Martin V. L. , McCoy E. L. , Dick W. A.
Published: July 2010

Crop residues produce alleochemicals that may inhibit corn [Zea mays (L.)] seed germination and early growth. Studies were conducted in which residues of corn, soybean [Glycine max (L.) Merr.], oat [Avena sativa (L.)], and mixed grass hay were extracted under N2 gas or air. Organic debris was removed and half of each extract was filter sterilized. Corn seeds were incubated in the extracts for 96 h at 25 °C. Percent germination, and lengths of coleoptile, radicle, and secondary roots were measured. Residues extracted under N2 gas or air did not differ significantly in their toxicity. Nonsterile residue extracts decreased germination to 74% for soybean and oat straw and 27% for corn and hay residues. Sterile extracts did not affect germination. Nonsterile soybean and oat extracts did not reduce coleoptile lengths but did reduce radicle and secondary root lengths by 34% compared to the water treatment. Sterilized extracts reduced radicle and secondary root lengths by 63%. Nonsterile corn and hay extracts reduced coleoptile lengths by 42% and radicle and secondary root lengths by 81%. A second extraction was performed by incubating the residues without aeration at 25 and 0.5 °C. Seed germination for treatments with nonsterile extracts obtained at 25 °C were similar to those for nonsterile extracts of Exp. 1. Extraction at 0.5 °C and filter sterilization also improved germination. Soybean and oat extracts did not strongly inhibit coleoptile lengths; however, a 61% reduction occurred in radicle and secondary root lengths for the sterilized, 0.5 °C extract. Corn and hay residues were generally more inhibitory to coleoptile, radicle and secondary root lengths; however, no consistent effects were observed from temperature and sterilization treatments.
Effects of Nitrogen, Dicyandiamide, and Tillage on Cotton Nitrogen Concentration and Yield
Authors: Gordon W. B. , Rickerl D. H. , Touchton J. T.
Published: July 2010

Conservation tillage has the potential to increase N leaching from sandy soils by increasing water infiltration. The nitrification inhibitor dicyandiamide (DCD) can reduce this risk, but cotton (Gossypium hirsutum L.) may be sensitive to DCD. Field studies were conducted at the E.V. Smith Research Center in Macon County, AL on a Norfolk soil (fine, loamy, siliceous, thermic Typic Paleudult) to determine the effects of DCD on cotton N concentration and yield of conventional and strip‐till cotton. Nitrogen treatments included four preplant N rates (0,67,100, and 134 kg ha−1) with and without DCD (10% of N rate). Leaf N concentration was generally greater in treatments receiving N fertilizer than no N; however, regressions between N concentration and N fertilizer were not always significant. Whole plot effects on yield due to tillage were significant. Optimum N rate for seed cotton production was 67 kg ha−1 N in 1984 and ranged between 100 and 134 kg ha−1 N in 1985 and 1986. The application of DCD decreased yields by 30% in 1984. At the 134 kg N ha−1 rate in 1985, DCD increased yields by 24%. In 1986 seed cotton yields in the strip‐till treatment receiving 134 kg ha−1 N were 20% less with DCD than without. It is concluded that application of DCD is beneficial, with typical rainfall patterns, if high rates (13 kg ha−1) are used. However, if rainfall is less than the historical average during first square to first bloom stage, DCD application has little effect or is detrimental to seed cotton yield.
Topical Cellulase Application Effects on Tall Fescue Digestibility
Authors: Forwood J. R. , Sleper D. A. , Henning J. A.
Published: July 2010

Two studies were conducted to assess the effects of topically applying a prepared cellulase solution (PCS) as a forage pretreatment to increase digestibility of tall fescue (Festuca arundinacea Schreb.). Fall regrowth and stockpiled tall fescue were harvested from the field (Mexico silt loam: fine montmorillonitic mesic Udollic Ochraqualf) and studied in laboratory Exp. 1 and 2, respectively. Experiment 1 involved topical application of 40 mL of PCS to 100 g (on a dry‐matter basis) dried and fresh leaf material that had either been chopped or remained whole. Further treatments involved 1‐, 6‐, or 12‐h drying times post‐application and freezing to curtail enzymatic activity or no freezing. Experiment 2 involved whole and chopped fresh leaf material with a surfactant treatment added and post‐application drying times altered to 1,12, 24, and 48 h. In vitro dry matter digestibility (IVDMD) of tall fescue was significantly increased (28 g kg−1) by topical application of PCS in both experiments. Allowing longer exposure time of herbage to PCS was not an advantage. Addition of a surfactant to PCS decreased IVDMD (36 g kg−1) but increased IVDMD (14 g kg−1) when PCS was not applied. Allowing the PCS to dry on herbage for 1‐, 12‐, and 24‐h post‐application resulted in significant IVDMD increases compared to no PCS (22,27, and 31 g kg−1, respectively) while PCS application most benefited IVDMD for 24 h. Scanning electron micrographs revealed cuticular disruption on leaf blades which may be at least partially responsible for increased IVDMD of PCS‐treated samples. These studies indicated that topical PCS treatment can extend existing forage supplies. Further studies under field conditions and animal trials are needed.
Maize Leaf Number Sensitivity in Relation to Photoperiod in Multilocation Field Trials
Authors: Bonhomme R. , Derieux M. , Kiniry J.R. , Edmeades G.O. , Ozier‐Lafontaine H.
Published: July 2010

The photoperiodic response of maize (Zea mays L.) determines the total number of leaves (LN). Knowledge of this is important for modeling phenology and for describing cultivar adaptation. The objective of this research was to evaluate artificial extension of photoperiod for field‐grown maize as a method of quantifying photoperiodic sensitivity. The LN response was quantified using data from six diverse maize cultivars grown at two field locations where natural photoperiods were artificially extended by 1.3 h to 7.3 h. These responses were then compared with LN observed in a field experiment of the same cultivars grown at 11 diverse latitudes. The relative ranking of photoperiod sensitivity among cultivars was similar for the two groups of experiments, although observed sensitivity was occasionally greater in artificial light experiments than in multilocation experiments. Photoperiod sensitivity was greater for the tropical than for the temperate cultivars, with mean sensitivities of 1.91 and 0.49 leaves h−1, respectively. The LN in tropical cultivars was reduced by 0.5 to 2.0 leaves plant−1 for every min d−1 increase in rate of change of photoperiod during the photoperiod‐sensitive stage. Artificial extension of daylength by lights mounted in the field appears to be an effective and efficient means of screening maize cultivars for photoperiodic sensitivity.
Lodging Effects on a Semidwarf and Two Standard Barley Cultivars
Authors: Jedel P.E. , Helm J.H.
Published: July 2010

Crop productivity in the black soil zones of western Canada can be affected by lodging when high biomass production and late season winds and rain occur. This experiment was conducted to assess the effects of mechanically induced lodging at different growth stages on three barley (Hordeum vulgare L.) cultivars. Five field trials were run at Lacombe, Alberta (Navarre loam, black Chernozemic), from 1985 to 1988. At anthesis, milk, soft‐dough, and hard‐dough growth stages, the semidwarf cultivar Samson, the mid‐height cultivar Leduc and the tall cultivar Johnston were subjected to lodging treatment. Yield losses for all cultivars tended to be greatest when lodging was, imposed at the milk stage with an average yield loss of 1.7 ± 0.4 Mg/ha. Significant losses also occurred with lodging at heading and soft‐dough stages with average yield losses of 1.3 ± 0.5 and 1.2 ± 0.7 Mg/ha respectively. Samson appeared to have the greatest tolerance to lodging, while Johnston had the least. Yield losses when lodging occurred at the hard‐dough stage were minimal with an average yield loss of 0.57 ± 0.49 Mg/ha. Test and kernel weights were not significantly affected by lodging. However for Johnston, kernel weight tended to be reduced by lodging and percent thin kernels was increased to 12.8% by lodging at the soft‐dough stage from 5.3% for the control. Significant yield losses can result from lodging and in areas where lodging is of concern, efforts should be made to breed for, and promote the use of, strong‐strawed cultivars such as the semidwarf cultivar Samson.
Mapping the Production and Survival of Fruit on Field‐Grown Cotton
Authors: Constable G. A.
Published: July 2010

The location and size of bolls on cotton (Gossypium hirsutum L.) plants influence yield and earliness, so plant mapping is being used to define plant fruiting patterns in response to pest damage or crop management. This study aimed to define patterns of fruit location, survival percentage, and final boll size that could provide base data for simulation models. The observations also measured differences created by irrigation treatments. Dates of fruit appearance or loss were recorded from three seasons of high‐yielding crops in field experiments on a gray clay (very fine, montmorillonitic, Typic Pellustert). The interval between squaring and flowering and between flowering and boll opening (boll period) was shorter at the top of the plant than at the bottom. Fruiting branches near but not at the bottom of the plant were the longest; they had the greatest survival of fruit to maturity, the largest bolls, and therefore the greatest contribution to yield. Boll size patterns up the plant reflected leaf size profiles, with largest bolls on fruiting branches at mainstem Nodes 7 to 13. The loss of a boll did not appear to be fully compensated for by more or larger bolls on the same fruiting branch. Fruit were most likely to be shed as young squares or as young bolls: fruit on the lower portion of the plant shed more often as squares; upper fruit shed more often as young bolls.