bluuebunny/crossref_metadata_2025 huggingface dataset:
Vegetation and Animal Production from Reclaimed Mined Land Pastures
Authors: Hofmann L. , Ries R. E.
Published: July 2010

Limited data are available on the productivity and persistence of reclaimed mined land in the northern Great Plains used for grazing. The purpose of this study was to compare standing crop, vegetation use, steer (Bos spp.) performance, soil compaction, and measurement methods on reclaimed cool‐season pasture near Center, ND, at three grazing intensities and grazed each spring over 5 yr. Light and moderate intensity pastures were grazed an average of 36 days, with an average total vegetation use of 35 and 47%, respectively. Heavy intensity pastures were grazed 27 days and averaged 93% use. Live vegetation production averaged 2040,2860,2390, and 1630 kg ha−1 dry matter in early July for ungrazed exclosures and light, moderate, and heavy intensities, respectively, over the 5 yr; litter averaged 1440, 1180,640, and 200 kg ha−1, respectively. Yearling steers gained an average of 64,86, and 31 kg ha−1 and 1.2, 1.0, and 0.3 kg day−1 at the light, moderate, and heavy intensities, respectively. The heavy intensity was detrimental to both vegetation and livestock production, but vegetation dry matter and liveweight gain improved when grazing was moderated in 1981. Grazing did not measurably affect soil bulk density in the top 150 mm of soil, but proving ring penetrometer measurements indicated increased soil compaction with increased grazing intensity. With 50% or less total vegetation removal in early summer, the reclaimed grassland provided sustained productive post‐mine grazing use with no signs of deterioration.
Irrigation and Plant Spacing Effects on Seed Production of Buffalo and Coyote Gourds
Authors: Nelson J. M. , Scheerens J. C. , McGriff T. L. , Gathman A. C.
Published: July 2010

Buffalo gourd (Cucurbita foefidissima HBK) and coyote gourd (Cucurbita digitata Gray) are xerophytic perennial cucurbits with potential as oilseed or starch crops for arid and semiarid lands. This study investigated irrigation and plant spacing effects on growth, water requirements, and oilseed production of these species. Irrigation of first‐season buffalo gourds planted in 1981 at a 610‐m elevation site on Pima clay loam [fine‐silty, mixed (calcareous) thermic Typic Torrifluvent], and irrigation and plant spacing were evaluated on first‐season buffalo and coyote gourds at a 360‐m site in 1983 on Casa Grande sandy loam (fine‐loamy, mixed, hyperthermic Typic Natrargid) and Trix clay‐clay loam [fine‐loamy, mixed (calcareous), hyperthermic Typic Torrifluvent], respectively. Irrigation and plant spacing were evaluated on second‐season buffalo gourds planted in 1983. Irrigation did not affect first‐season buffalo gourd yields. Second‐season yields were reduced by irrigating when the available soil water was 75% depleted (I2) compared to irrigating when soil water was 50% depleted (I1). Coyote gourd yields were reduced by the I2 treatment in 1983 but not in 1984. Consumptive water use for first season buffalo gourds in the I1 treatment at the 610‐ and 360‐m sites was 870 and 645 mm, respectively. Consumptive water use was similar for coyote and buffalo gourds at the 360‐m site. In the first season, these species derived up to 50% of water used from the top 0.4 m of soil, and extracted water to a depth of at least 2.6 m. Irrigation did not affect water‐use efficiency (WUE) of either species. Buffalo gourds had higher WUE in the second season (0.09 kg seed m−3 water) than the first season (0.04 kg m−3). Plant spacings of 0.25 to 2 m in 1‐m spaced rows had no effect on first‐season yield in 1983, but in 1984 a quadratic relationship indicated that the closest and widest spacings reduced yields. Coyote gourd consistently outyielded buffalo gourd at the 360‐m site. Although these gourd species have promising water use characteristics for arid lands agriculture, the low seed yields of the cultivars currently available appear to limit their potential as oilseed crops.
Light Absorption and Competition in Mixed Sorghum‐Pigweed Communities
Authors: Graham P. L. , Steiner J. L. , Wiese A. F.
Published: July 2010

Plant productivity in a community is governed in part by its ability to absorb and utilize photosynthetically active radiation (PAR). Studies on weed competition with a crop for light are limited. The effect of pigweed (Amaranthus hybridus L. and A. palmeri S. Wats) competition on leaf area development, light absorption, and dry matter production of fully developed grain sorghum [Sorghum bicolor (L.) Moench] was evaluated in a field experiment on Pullman clay loam (a fine, mixed, thermic Torrertic Paleustoll) at Bushland, TX, in 1984. Profile measurements (0–0.3, 0.3–0.6, 0.6–0.9, and >0.9 m above ground) of absorbed PAR (APAR) and leaf area index (LAI) by species were taken at four densities of pigweed (0, 1, 4, and 12 plants m−2). APAR calculated for sorghum in mixed communities of 1,4, and 12 pigweed plants m−2 was 79,77, and 49% of the APAR in weed‐free sorghum. Sorghum LAI was reduced to 81, 65, and 37% of the LAI of weed‐free sorghum in canopies with 1, 4, and 12 pigweed plants m−2. Sorghum LAI was concentrated in the 0.3‐ to 0.6‐m layer, while the taller pigweed plants had the greatest leaf area concentration above 0.6 m. By absorbing light in the upper canopy, pigweed reduced light penetrating into sorghum. Leaf measurements of photosynthesis and transpiration rates, leaf temperature, and stomatal resistance indicated a relatively minor degree of water stress under full canopy and high potential evaporation conditions; the level of water stress measured was not adequate to explain sorghum dry matter reduction in plots with 1, 4, and 12 pigweed plants m−2 to 78, 56, and 28% of that in weed‐free sorghum.
Herbicide Efficacy for Various Application Times in Doublecrop Wheat and Soybean
Authors: Higgins Jeffery M. , Whitwell Ted , Toler Joe E.
Published: July 2010

Effective weed management is essential in reduced tillage doublecrop wheat (Triticum aestivum L.) and soybean [Glycine max Merr.] production. Field experiments were conducted on a Hartsells fine sandy loam soil (fine loamy, silaceous, thermic Typic Hapludalfs) near Crossville, AL, from 1981 to 1983 to determine the influence of application time on herbicidal efficacy of oryzalin [4‐(dipropylamino)‐3,5‐dinitrobenzenesulfonamide], pendimethalin [N‐(1‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine], and oryzalin + 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] for weed control. Herbicides were applied early preplant (EP) to fully tillered wheat, and preemergence (PRE) at soybean planting. Paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) was applied separately at 0.3 kg ha−1 at the time of PRE applications to ail plots that received other herbicide applications (EP or PRE) and alone as a check treatment. Early preplant treatments did not reduce wheat seed yields in 2 of 3 yr compared to the untreated control. Fall panicum (Panicum dichotomiflorum Michx.) and prickly sida (Sida spinosa L.) control were similar with EP and PRE applications of all herbicides. Fall panicum control ranged from 63 to 100%, and prickly sida control from 20 to 87%. Early preplant applications provided greater Pennsylvania smartweed (Polygonum pensylvanicum L.) control than PRE applications. Pennsylvania smartweed control was 5 to 70% greater with EP applications compared to PRE applications. Preemergence applications of oryzalin + 2,4‐D produced moderate (20%) soybean injury in 1982 and 1983. Soybean seed yields were similar with EP and PRE applications in 1981 and 1982; however, seed yields were from 26 to 103% greater with EP applications than PRE applications in 1983.
Performance of Orchardgrass, Smooth Bromegrass, and Ryegrass in Binary Mixtures with Alfalfa
Authors: Casler M. D.
Published: July 2010

Forage grass cultivars used in grass‐alfalfa (Medicago sativa L.) mixtures are generally the same as those used in pure stands. Little is known about the relative performance of grass cultivars in grass‐alfalfa mixtures in temperate North America. The objective of this study was to evaluate 78 cultivars and experimental populations of three species—orchardgrass (O), Dactylis glomerata L.; smooth bromegrass (SB), Bromus inermis Leyss.; and ryegrass (R), Lolium perenne L. and L. hybridum Hausskn.—for persistence and competitive ability in binary mixtures with alfalfa. Entries were seeded in 3‐m single‐row plots, spaced 0.9 m apart, in six randomized complete blocks at Arlington, WI, and overseeded with ‘Saranac’ alfalfa in April 1983. Plots were managed for 3 yr following the seeding year by taking three cuttings at late bud to early flower of alfalfa before 1 September. Species rankings for vigor and ground cover were O > SB > R; rankings for regrowth after cutting were O > R > SB. Orchardgrass increased in ground cover in each year, SB decreased in the first year and increased in subsequent years, while R decreased in the first year and remained nearly constant for the duration of the study. True ground cover ratings (TGC, expressed as a percentage of initial established stands) ranged from 46 to 508% for O, 31 to 233% for SB, and 21 to 81% for R. Cultivar variation for TGC was related to maturity in O, prior selection history in SB, and ploidy and species in R. Variation among entries was generally not related to performance in pure stands. The study provided an efficient procedure for developing preliminary evaluations of cultivars and experimental populations in mixture with alfalfa.
Simulating Growth and Yield Responses of Sorghum to Changes in Plant Density
Authors: Huda A. K. S.
Published: July 2010

Though numerous field experiments have been conducted on the effects of plant density on growth and yield of sorghum [Sorghum bicolor (L.) Moench], tests showing the ability and validity of a sorghum simulation model to respond to changes in plant density have not been reported previously. Thus, a field experiment was conducted at ICRlSAT Center, Patancheru, India, in the 1983 rainy season on a Vertisol (fine, clayey, montmorillonitic, isohyperthermic Typic Pellustert) to test the validity of the sorghum simulation model, SORGF, for simulating the effect of plant density on growth and development of sorghum. Simulations were compared to data collected on phenology, leaf area indices (LAI), total dry matter (TDM), and grain yield for five plant densities (4, 8, 12, 16, and 20 plants m−2) of two sorghum cultivars (CSH 6 and SPV 351). Observed TDM and grain yield increased up to 16 plants m−2, while simulated TDM and grain yield increased up to 20 plants m−2. The model, on average, underestimated TDM by 8% and overestimated grain yield by 2%. Good agreement between observed and simulated LAI, TDM, and grain yield across five plant densities and two cultivars was supported by the insignificant differences of observed and simulated values from a one‐to‐one line. The model was further validated using climatic data from the ICRISAT Center between 1976 and 1984. Simulated grain yield using plant densities of 12 plants m−2 were within 3% in 6 yr and between 11 and 20% in the other 3 yr of observed data using plant densities of 13 plants m−2. Results from this study suggest that the SORGF model appears useful for simulating the effect of plant density on the growth and yield of well‐managed sorghum when input data on cultivar, climate, soil, and agronomic management are available.
Nutrient Norms for Cured Burley Tobacco
Authors: Evanylo G. K. , Sims J. L. , Grove J. H.
Published: July 2010

Tobacco (Nicotiana tabacum L.) cured leaf yield, price, and total alkaloid concentration can be altered through appropriate fertilization programs. A study was undertaken to establish critical values and Diagnosis and Recommendation Integrated System (DRIS) norms using total N, NO3–N, P, K, Ca, Mg, Mo, Mn, Na, Cl, and S for burley tobacco grown on Maury silt loam (Typic Paleudalf) and associated soils in Central Kentucky. Preliminary sets of critical nutrient level and DRIS norms were calculated for cured burley tobacco leaf using a data bank of 500 observations collected from 15 field studies conducted between 1972 and 1984. Differences in optimum nutrient levels and DRIS ratios existed between subpopulations created using a single dividing criterion for yield, price, or total alkaloid concentration. Narrower nutrient ranges were required for high‐yielding than for high‐priced, or for low total alkaloid‐containing leaf. Leaf total N concentration did not vary among high‐yielding, high‐priced, or low alkaloid‐containing tobacco. High K concentrations were more important in attaining high yield than high price. Low Cl and high S concentrations were associated with low total alkaloids. The proposed norms should serve as useful guides in burley tobacco research or production to optimize tobacco composition for quality and safety without concurrent loss in yield.
Management Effects on Kernel Breakage Susceptibility of Early Maturing Corn Hybrids
Authors: Moes J. , Vyn T. J.
Published: July 2010

The tendency of corn (Zea mays L.) kernels to break during post‐harvest handling causes problems for several user groups. Crop management factors have been reported to influence breakage susceptibility, but the effects of hybrid, plant density, harvest moisture content, and drying temperature on grain corn breakage susceptibility have not yet been investigated in a single study. To this end, a field experiment was established in May 1985, at the Arkell Research Station, Arkell, Ontario. Five commercial hybrids, Hyland HL2280, DeKalb XL11, Co‐op 2645, First Line 1636, and Pioneer 3949, were grown at 5.6 and 7.1 plants M2, harvested at 310 and 240 g kg−1 moisture content (wet basis) and dried at 30 and 80°C to approximately 150 g kg−1 moisture content. A Wisconsin Breakage Tester was used to measure breakage susceptibility. In the breakage tests, the main effects were statistically significant, as well as the interactions of hybrid with plant density, harvest moisture, and drying temperature, and of harvest moisture with drying temperature. Of these, only the interaction of hybrid with drying temperature resulted in differences large enough to be commercially significant. Four hybrids were relatively resistant to breakage when dried at 30°C; when dried at 80 °C, increases in breakage susceptibility were much larger for two hybrids than for the other three. Of the other parameters measured, the degree of multiple stress cracking and kernel length were most strongly related to breakage susceptibility, but levels of severe kernel damage and fine broken corn ( <4.76 mm), and kernel thickness were also related to breakage susceptibility. Test weight was not related to breakage susceptibility.
Effect of Added Urea and Potassium Chloride on Yields of Corn over Four Years and on Soil Potassium
Authors: MacKenzie A. F. , Phillip L. E. , Kirby P. C.
Published: July 2010

Silage corn (Zea mays L.) is a major crop in eastern Canada, and yield increases due to added N and K have been noted. However, possible interaction between N and K, and the effect of weather conditions on yield response and maturity must be determined for rational use of N and K fertilizers. A fertilizer experiment on the production of silage corn using urea and KCI was established on an Ormstown silty clay loam (fine silty, mixed, non‐acid, mesic Typic Humaquept) for 4 yr. Rates of fertilizer were 0, 90, and 180 kg N ha−1, and 0, 60, and 120 kg K2O in the first 2 yr, increased to 0, 120, and 240 kg K2O ha−1 in the last 2 yr. Yields of silage corn were increased with N in 3 yr and with K in 2 of the 4 yr. An interaction between N and K was found in the years when there were yield responses to added KCl, indicating that increased crop yields with K occurred only at relatively high N rates. Added N increased dry matter contents of corn plants, whereas added K reduced dry matter contents at low rates of N. Relative yields of the control plots over the high N–K plots were correlated positively with precipitation during the growing season. Added urea when combined with added KCl increased exchangeable and soluble K, probably due to reduced K fixation by illite, mica and vermiculite minerals in the soil.
Use of Unsaturated Salt Solutions to Generate Leaf Tissue Water‐Release Curves
Authors: Livingston N. J. , de Jong E.
Published: July 2010

Osmotic adjustment and changes in cell wall elastic modulus are important processes that enable plants to maintain physiological activity and prolong leaf survival as plant water deficits increase. This paper describes a simple and practical technique to produce tissue water‐release curves that allows many measurements of osmotic potential (π), elastic modulus (ε), and apoplastic water fraction (A) to be made both rapidly and routinely. Discs, 6 mm in diameter, were punched out of hydrated leaves of wheat (Triticum aestivum L.), barley (Hordeum distichon L.), and oil‐seed rape (Brassica napus and B. campestris) and weighed immediately on a precision balance. Each disc was then suspended above an unsaturated salt solution of known molality in a sealed test tube held at 5°C in a stirred water bath. Eighteen salt solutions were used whose water potentials ranged from −0.09 to −4.67 MPa. After 12 h the discs were reweighed and then oven dried at 65°C for 24 h. Water‐release curves were obtained by plotting paired values of disc relative water content and salt solution water potential. Using leaves from the same stem, π, at full and zero turgor, ε, and A determined from the water‐release curves were compared with pressure chamber measurements made on the next lower leaf. Measurements of wheat, barley, and oil‐seed rape π, ε, and A obtained from water release curves generated using salt solutions were within 0.2 MPa for π, 3.0 MPa for ε, and 0.07 for A, of those obtained using a pressure chamber over a wide range of π and ε. More than 40 water‐release curves could be generated over 2 d.
Subterranean Clover Reseeding
Authors: Evers G. W. , Smith G. R. , Beale P. E.
Published: July 2010

Hard seed production is critical for reseeding of winter annual clover (Trifolium, spp.) under southeastern U.S. climatic conditions. This study was conducted to determine the reseeding capability of a diverse set of subterranean clovers (Trifolium subterraneum L., T. yanninicum Katzn. and Morley, T. brachycalcinum Katzn. and Morley). Thirty‐three subterranean (sub) clover entries were grown in small, replicated plots in fall 1982 to spring 1983 at Angleton (Typic Pelludert) and Overton (Glossic Paleudalt), TX. Reseeding was monitored from June 1983 through December 1985 by counting and removing volunteer sub clover seedlings. Seedling density for all entries at both locations in the first reseeding year (June 1983‐May 1984) accounted for 69% or more of the total seedlings observed during the 2.3‐yr period. In the first reseeding year at Angleton, 15 entries germinated more seed from June to 15 September (summer) than from 15 September to January (fall). Seed survival at Angleton into the second reseeding year was less than 10% of total for all the cultivars evaluated except ‘Meteora’. In the first reseeding year at Overton, only the cultivar ‘Nangeela’ had a higher summer than fall germination. Seed survival at Overton into the second reseeding year was 21 and 29% for the cultivars ‘Esperance’ and ‘Clare’, compared to less than 1% for ‘Mt. Barker’. Summer seed germination was higher and second‐year seed survival less at Angleton compared to Overton. Sub clover reestablishment was adequate for most entries in the first reseeding year at both locations, but reseeding estimates were marginal to very low for most entries in the second and third years. Sub clover germplasm with improved reseeding potential was identified.
Microcomputer Simulation of Expected Gains from Eight Methods of Intrapopulation Recurrent Selection
Authors: Coors J. G. , Staub J. E. , Senalik D. , Rinehart C. A.
Published: July 2010

An interactive microcomputer program was developed to provide plant breeders and graduate students in quantitative genetics the opportunity to devise selection strategies and review expected gains for eight intrapopulation selection methods. Selection methods include uniparental and biparental mass selection, three forms of half‐sib selection, full‐sib selection, and S1 and S2 selection. Users provide estimates of genetic and environmental components of variance, selection intensities, and an array of possible experimental designs including number of environments, number of replicates within environments, and plot size. Expected gains can be expressed as either gain cycle−1, gain year−1, or gain season−1. Help screens are included that explain selection methods and the calculation of expected gains. The program is designed so the user can easily move within it, reenter values for individual variables, and rapidly redisplay results.
Water Use Efficiency and Dry Matter Distribution in Nitrogen‐ and Water‐Stressed Winter Wheat
Authors: Heitholt J. J.
Published: July 2010

Water use efficiency (WUE) and the distribution of dry matter to the roots in wheat (Triticum aestivum L.) are potential selection criteria for improving yield under water stress. The objectives of this research were (i) to compare methods of measuring WUE, and (ii) to determine the distribution of dry matter between shoots and roots in water‐ and N‐stressed wheat. Winter wheat was grown in a potting mixture for 6 wk in growth chambers with varying levels of N and water. Nitrogen applied to the mixture varied from 10 to 100 mg N per plant. Water supply was maintained at 15 to 35% of the mixture water holding capacity (stressed) to above 50% of capacity (well watered). Cumulative transpiration, steady‐state CO2 and H2O exchange rates, and dry matter were determined. The ratio of dry matter production (mmol C) to transpiration (mol H2O) averaged 1.39 and 1.94 mmol C mol−1 H2O for the 10 and 100 mg N treatments, respectively. The ratio of the steady state CO2 exchange rate to the H2O exchange rate was 1.97 and 4.24 mmol C mol−1 H20 for the 10 and 100 mg N treatments, respectively. The gas exchange WUE values tended to be higher than the gravimetric WUE values, but the two were correlated (r = 0.76**). Results supported the hypothesis that gas exchange WUE values could provide an accurate prediction of WUE values obtained from gravimetric analysis. Shootroot ratio was consistently reduced by N stress, but not by water stress. The results supported previous observations that optimal leaf N concentration promoted higher WUE. Mild water stress did not consistently affect WUE, but a more severe water stress consistently decreased WUE, especially under suboptimal N supply.
Tramlines, Row Orientation, and Individual Row Effects on Solid‐Seeded Soybean Plot Comparisons
Authors: Philbrook B. D. , Oplinger E. S.
Published: July 2010

Evaluations of solid‐seeded soybean [Glycine max (L.) Merr.) and other crops in solid‐seeded research plots without damage to plants from equipment can be difficult. This study was conducted to determine how individual rows of solid‐seeded soybean plots responded to the additional space of tramlines within the border rows, and if the effects varied with row orientation or cultivar. Cultivars Evans, Hodgson 78, and Hardin were planted in the field in seven 0.18 m harvest rows and two 0.28 m border rows as plots in north‐south (N‐S) and east‐west (E‐W) orientations near Arlington, WI from 1983 to 1985. The additional space between harvest and border rows served as tramlines through the plots, and imparted 28% more area to each of the two outside harvest rows than each of the other harvest rows. East‐west row orientation had a lodging rating 0.4 units (0 to 5 scale) greater than N‐S orientation in 1984, but no yield difference. In 1985 N‐S orientation outyielded E‐W by 410 kg ha−1. Final plant stands in the rows next to tramlines averaged 10% less than the five center plot rows, but yields averaged 18% greater in compensation for the tramlines. The second rows from tramlines also yielded higher than three center rows, and contributed an additional 7% average yield. Performance estimates using seven rows between the tramlines were no different than those from the center three rows, which were guarded from the tramlines by two rows on each side. Cultivar yields varied, but relative performance was not influenced by tramlines or row orientations. We conclude that tramlines can be used in a plot planting system for accurately testing cultivars or treatments in solid‐seeded soybean.
Irrigation Method and Water Quality Effect on Peanut Yield and Grade
Authors: Adamsen F. J.
Published: July 2010

Peanut (Arachis hypogaea L.), irrigated only recently in the coastal plain region of Virginia and North Carolina, is produced in an area where sodic deep water sources are more readily available than high quality shallow water sources. The objective of this work was to determine the effect of irrigation water quality and irrigation method on the yield and grade of peanut. Virginia‐type peanuts (cv. VA 81B) were grown on a Kenansville loamy sand (loamy, siliceous, thermic Arenic Hapludult) in Suffolk, VA from 1984 to 1987. Peanuts were irrigated with either overhead sprinklers or deep buried trickle lines using deep‐well (142 m) and shallow‐well (10 m) water. Trickle lines were buried 350 to 410 mm below each row. Deep‐well water had 220 mg Na L−1, a pH of 8.5, and a sodium adsorption ratio (SAR) of 103. Shallow‐well water had 4.8 mg Na L−1, a pH of 4.8, and an SAR of 3.1. Shallow‐well, trickle‐irrigated peanuts yielded 5003 kg ha−1 or 14% higher than the nonirrigated treatment. Deep‐well, sprinkler‐irrigated peanuts averaged 4374 kg ha−1 for 4 yr, which was 21 kg ha−1 lower than the nonirrigated treatment. The price of deep‐well, sprinkler‐irrigated peanuts was also lower than all other treatments due to lower percentages of extra‐large kernels, total sound mature kernels, and fancy pods. Deep‐well water applied below 300 mm through trickle irrigation produced peanuts of comparable quality and quantity as the shallow‐well, trickle, or sprinkler‐irrigation treatments. Irrigation of peanuts was beneficial in this humid region. There was no difference in peanut yield or grade when sprinkler or trickle irrigation was used with good quality irrigation water, but trickle irrigation required only 44% as much water. With a sodic water source, trickle irrigation was superior to sprinkler application.
Ethephon as a Morphological Regulator for Corn
Authors: Konsler J. V. , Grabau L. J.
Published: July 2010

Ethephon (2‐chloroethyl phosphonic acid) has been used to reduce ear height in order to improve lodging resistance of corn (Zea mays L.). However, untimely applications may reduce area of photosynthetically important ear leaves. Thus our objective was to determine the range of plant development stages over which ear height reduction could be achieved without advesrsely affecting ear leaf area. Two corn hybrids were space planted in the field in 1986 and 1987, and treated with ethephon at 284 g ha−1 over a range of vegetative growth stages. Ear heights were most reduced by ethephon applications from V9.2 to V10.6 in 1986 and at V13.0 in 1987. Individual internodes most influenced by ethephon were those actively elongating at the time of application. The area of the three ear leaves was most sensitive to treatments from V5.3 to V9.2 in 1986 and V6.0 to V8.8 in 1987. Early (V3.7 to V4.3) or late (V13.4 to V16.8) vegetative—stage application did not reduce grain yield per plant, while those treatments that most influenced area of ear leaves had a similar negative effect on grain yield. For the hybrids studied, the growth stages for which applications produced the best combination of ear height, ear leaf area, and grain yield were from V10 to V13, corresponding to developing tassel lengths of 30 to 300 mm. When ethephon rates were expressed as mg g−1 dry weight, more of variation in ear height, leaf area, and grain yield was explained than when rate was expressed as mg ethephon per plant. This implied that some growth regulator effects referred to as “timing” influences may be better explained as “dosage” effects. Additional research under higher planting rates will be necessary to validate these results.
Evaluating Plant Water Stress with Canopy Temperature Differences
Authors: Clawson K. L. , Jackson R. D. , Pinter P. J.
Published: July 2010

The temperature stress day (TSD) has been used as a remotely sensed indicator of plant water stress without a thorough knowledge of TSD behavior. The purpose of this study was to demonstrate a dependence of the TSD on net radiation (Rm), air temperature (Ta), and atmospheric water vapor pressure deficit (VPD), and to evaluate a replacement water status index. The dependence on these parameters was proven by the following methods: (i) theoretically, using the Penman‐Monteith resistance equation; (ii) empirically, using the non‐water‐stressed baseline equation relating canopy and air temperatures to VPD; and (iii) in a field experiment with alfalfa [Medicago sativa (L.)] on an Anthropic Torrifluvent soil. The effect of these parameters caused the field‐measured TSD to vary up to 7 °C, rendering its utility as a plant stress indicator questionable. A modification of the crop water stress index (CWSI), which accounts for Rn, Ta, and VPD, was proposed as the TSD replacement. The modification consisted of using a measured instead of estimated well‐watered canopy temperature (Tcl) in the canopy temperature ratio defined by the CWSI. This modification obviates the need for the canopy resistance value required to calculate the theoretically based CWSI. The modified CWSI responded to imposed irrigation regimes as indicated through yield and evapotranspiration comparisons. The modified CWSI appears to be a suitable replacement for the TSD by accounting for environmental dependence while maintaining the measurement simplicity of the TSD.
Light Competition Simulation Technique for Sod‐Seeded Crops
Authors: Evers G. W.
Published: July 2010

Competition for light is critical for successful establishment of clover in a perennial grass. This study was conducted to evaluate a greenhouse technique for screening germplasm for tolerance to reduced light. Tubes cut from PVC pipe were placed on ‘Bigbee’ berseem clover (Trifolium alexandrinum L.) seedlings at the cotyledon, unifoliate, and first and second leaf stages. Tube heights within each growth stage were 0,25, 51,76,102, and 152 mm. Weight, leaves, and nodules per seeding decreased as tube height increased while plant height did not decrease until the 76 mm tube. There was a general increase in these plant parameters as tube placement was delayed.
Yield and Quality Response of Subirrigated Meadow Vegetation to Nitrogen, Phosphorus and Sulfur Fertilizer
Authors: Nichols James T. , Reece Patrick E. , Hergert Gary W. , Moser Lowell E.
Published: July 2010

Production practices that increase hay yields are important for beef cattle producers in the Nebraska Sandhills. This study evaluated the responses of subirrigated meadow vegetation to fertilization with N, P, and S over a 4‐yr period. A factorial array of four levels of N (0, 45, 90 and 135 kg ha−1), two levels of P (0 and 20 kg ha−1) and two levels of S (0 and 22 kg ha−1) were applied each year to the same plots, arranged in a randomized complete block design. Average dry matter yields were increased by N, P, and S. There were no fertilizer interaction effects. Yields increased quadratically as N levels increased. For each 45 kg increment of N applied from 0 to 135 kg ha−1, dry matter yield (pooled over P and S) increased 1002, 703, and 402 kg ha−1, respectively. Main effects of P and S increased dry matter yields by 4662 and 577 kg ha−1, respectively. Nitrogen uptake was increased linearly by fertilization with N, P, and S. Forage N use efficiency decreased as N fertilizer rates increased. Crude protein (CP) declined quadratically as N rates increased, but the maximum change was less than 10 g kg−1. In vitro dry matter digestibility (IVDMD) declined linearly as N rates increased. Sulfur and P did not affect either CP or IVDMD. Yield responses were sufficient to justify the use of N, P, and S to increase subirrigated meadow production. Loss of forage quality (CP and IVDMD) was not sufficient to nullify this conclusion.
Spring Wheat Response to Herbicides Applied at Three Growth Stages
Authors: Martin Duane A. , Miller Stephen D. , Alley Harold P.
Published: July 2010

Since the inception of 2,4‐D [(2,4‐dichlorophenoxy) acetic acid], many herbicides have been developed for broadleaf weed control in wheat (Triticum aestivum L.). However, many of these herbicides have not been thoroughly evaluated with respect to application timing and effects on wheat yield and quality. Field studies were conducted at Torrington, WY on a Bayard fine sandy loam (coarse loamy, mixed, mesic Torriothentic Haplustoll) in 1984 and 1985 to evaluate the response of ‘Oslo’ spring wheat to 10 broadleaf herbicide treatments applied at three growth stages. Dicamba (3,6‐dichloro‐2‐methoxybenzoic acid), dicamba plus 2,4‐D and dicamba plus MCPA [(4‐chloro‐2‐methylphenoxy)acetic acid] reduced wheat yield 28, 21 and 24%, reduced kernels per spike 27, 33 and 21%, and increased seed protein 8, 10 and 13%, respectively, when applied at Zadoks Stage 44 (mid‐boot). Several other auxin herbicides increased seed protein content, particularly when applied at Zadoks Stage 44. Proline and lysine content were not influenced by herbicide treatment at any stage of application. Spring wheat tolerance to bromoxynil (3,5‐dibromo‐4‐hydroxybenzonitrile), chlorsulfuron (2‐chloro‐Ar‐[[4‐methoxy‐6‐methyl‐l,3,5‐triazin‐2‐yl)amino]carbonyl] benzenesulfonamide} and MCPA was excellent regardless of growth stage at application.
A Soil Water Balance and Dry Matter Production Model: I. Soil Water Balance of Oat
Authors: Ragab R. , Beese F. , Ehlers W.
Published: July 2010

A simulation study of the soil water balance under oat (Avena sativa L.) was carried out on a Typic Hapludalf soil, at two sites near Göttingen, West Germany during 1976,1977,1982, and 1983. The model used describes the plant water uptake rate as a function of soil matric potential and rooting depth. Inputs needed for the model are soil physical parameters, daily meteorological data, rooting depth, leaf area index, and plant height. The goal was to test the usefulness of the model in predicting the soil water balance components and to determine if the plant water uptake rate, as a potential important factor for crop yield, can be simulated by applying a rather simple approach. Simulated water uptake rate, actual evapotranspiration rate, water storage in the soil profile, and soil water profiles, compared reasonably well with the measured values in the 4 yr studied. Since some of the model input parameters were derived from the 4‐yr experimental data, the model remains to be tested against an entirely independent data set.
A Soil Water Balance and Dry Matter Production Model: II. Dry Matter Production of Oat
Authors: Ragab R. , Beese F. , Ehlers W.
Published: July 2010

A simulation study on dry matter production of oat (Avena sativa L.) was carried out on a Typic Hapludalf, at two sites near Göttingen, West Germany, during 1976,1977,1982, and 1983. The model used in this study is a Blackman‐type production model in which a maximum production level is considered. The model simulates the yield as a function of radiation energy and water supply in the presence of an optimal nutrient supply. Input values required include daily climatic data, canopy parameters, and water uptake rate. The aim was to test the usefulness of the model when a complete field data set is available. The results indicate that the simulated values for total dry matter (shoot + roots) and shoot dry matter compared well with measured values. The sensitivity analysis showed that careful consideration should be given to the input values for maximum water use efficiency and respiration factors. The study reveals that oat dry matter production can be simulated, provided that the proper parameters are used. Since some of the required inputs were derived from the 4‐yr experimental data, the model remains to be tested against a truly independent data set.
Computer Program to Print Adhesive Identification Labels for Research
Authors: Graff Paul S. , Hipp Billy W.
Published: July 2010

Using microcomputers to produce adhesive labels for research samples saves time and effort, and reduced potential for errors in labeling. To our knowledge, no programs written solely for this purpose have been made publicly available for personal computers using MS‐DOS.1 Our program produces sequentially incremented labels using “skeletal” information such as study title/location, list of treatments, number of replications, and material(s) sampled. Templates with this information can be stored and recalled for individual experiments. Bar codes (UPC, Uniform Code Council, Inc., Dayton, OH, and Code‐39 Interface Mechanisms, Inc., ynnwood, WA) with encoded treatment/replication information are optionally printed. The program requires 185K RAM, a 360K floppy disk drive, a printer, and continuous‐form (pin‐fed) adhesive labels.
Potassium Uptake and Recovery by an Upland Rice‐Soybean Rotation on an Oxisol
Authors: Gill D. W. , Kamprath E. J.
Published: July 2010

A major limitation to improved crop growth on many acid Oxisols is low K availability. A field experiment was conducted in West Sumatra to study the effects of K fertilization of an oxisol under three levels of lime (0.375, 2.25 an 5 t ha−1) on K accumulation of a yearly upland rice (Oryza sativa L.)‐soybean (Glycine max L. Merr.) rotation where all above‐ground residue was removed. Six K treatments supplied 0 to 240 kg K ha−1 to each crop and lime treatment. Potassium fertilization increased grain yields of rice and soybean and K content of grain and stover of both crops. With both crops a large proportion of the K was present in the stover. Liming had no effect on K accumulation Of rice grain; an inconsistent effect on K accumulation in rice straw; and significantly increased the K content of soybean grain and stover. Upland rice was very efficient in utilizing K applied to that crop as well as residual soil K from previous fertilization. When K rate was greater than 100 kg ha−1 per crop appreciable amounts of K could not be accounted for indicating that the K was lost by leaching. Increases in exchangeable K with K fertilization only occurred in the 0‐ to 30‐cm depth.
Cluster Analyses for Analyzing Two‐Way Classification Data
Authors: Lin C. S. , Butler G.
Published: July 2010

The interaction structure of two‐way classification data often can be identified if the data are stratified into homogeneous subsets. Four cluster methods, two new and two originally developed for investigating genotype × environment (GE) interaction, are proposed for this purpose. The four methods differ in the dissimilarity indices depending on whether the regression model or ANOVA model is used, and whether the similarity is specified with respect to the GE interaction alone or with respect to the genetic effect and GE interaction combined. The same cluster algorithm of averaging the dissimilarity indices between all pairs of individuals in the two groups is used for all. A unique feature of these methods is that the dissimilarity index defined or constructed at any cluster cycle, is equivalent to the mean square of the respective ANOVA for the grouped genotypes. The direct link between the cluster analysis and conventional ANOVA provides a convenient way of determining the cutoff point based on tire F‐ratio of the smallest dissimilarity index and the error estimate. When the calculated F‐ratio exceeds the tabular F‐value the cluster process should be stopped. Since the smallest dissimilarity index at each cluster cycle is monotonically increasing, this stopping rule assures that all individuals within the groups are homogeneous with respect to defined characteristics. The stratification of data sets (by these methods) leads to the revelation of complex data structures as demonstrated by several works cited.
Structure of Tall Fescue Swards and Intake of Grazing Cattle
Authors: Arias J. E. , Dougherty C. T. , Bradley N. W. , Cornelius P. L. , Lauriault L. M.
Published: July 2010

Models of grazing systems need logic that estimate herbage intake of livestock from physical and chemical properties of the sward. Changeover designs were used to study the effects of sward structure of tall fescue (Festuca arundinacea Schreb. cv. Kenhy) on ingestive behavior of grazing cattle. Fourteen (Tl), 21 (T2), and 28 (T3) days of growth established sward surface heights of 16, 20, and 22 cm, with herbage dry matter (DM) masses (>5 cm) of 0.84, 1.43, and 2.16 Mg ha−1. When each of 12 2‐yr‐old Angus heifers (Bos taurus L.) (liveweight, 381 kg) were allocated the same grazing area (26 m2), with DM allowances (>5 cm) of 2.2,3.7, and 5.6 kg for 90 min of grazing, heifers ingested DM at 1.07, 1.65, and 2.03 kg h−1, with herbage DM intakes per bite of 0.45, 0.65, and 0.82 g and consumption of 75, 69, and 57% of allowance for T1, T2, and T3, respectively. Rates of biting were not flected by sward treatments and averaged 42 bites min−1. The grazing horizon of the vegetative tall fescue tillers was limited to a plane above the tops of pseudostems and ingestive behavior reflected the properties of herbage in that horizon.
Minimum User‐Interface Standards and Software for Agricultural Expert Systems
Authors: Meyer C. R.
Published: July 2010

Agricultural Expert Systems (AES) are gaining recognition as technology transfer devices. It is increasingly clear that lack of uniformity in their presentation to the user creates unnecessary obstacles to their acceptance. Some agronomic expert system applications require performance and economy not currently available with commercial expert system development shells.

A group of expert system developers resolved to establish uniform standards for the part of an AES a user must interact with. A committee was appointed to draft the standards from their collective experience. Software was developed to implement these standards in expert systems, without sacrificing performance and economy. Two lists of standards were developed: mandatory and desirable. These are minimal features, and extended or enhanced features, respectively. The lists were compiled and refined through study of existing programs, current definitions, developers' experience, and user input. Software to meet the standards was developed in C language, in conjunction with an expert system. This permitted interactive refinement of both the standards and the software. The standards for AES features were endorsed by two groups of cooperating AES developers. Public domain source code is available to implement the features mentioned above, in the C programming language. Concurrence upon the two lists of standards proved to be possible. Adherence to such standards is desirable, since it reduces user confusion. Including these features in programs not usually thought of as expert systems, is easy, inexpensive, and greatly increases their acceptability to new users.
Estimation of Botanical Composition in Alfalfa/Ryegrass Mixtures by Near Infrared Spectroscopy
Authors: Shaffer J. A. , Jung G. A. , Shenk J. S. , Abrams S. M.
Published: July 2010

Determining the botanical composition of forage samples by near infrared reflectance spectroscopy (NIRS) can save time and expense. The purpose of this study was to test the efficacy of NIRS technology for predicting botanical composition of forage samples. Estimating the number of samples required for reliable calibration equations, determining if pooling calibration samples across locations and years (broad‐based) would improve accuracy and precision, and comparing NIRS errors with experimental and sampling errors were primary objectives. Samples were collected from four different alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.) management trials. Calibration samples were hand‐separated into alfalfa, ryegrass, and weed components and each component was dried and weighed. Alfalfa and ryegrass components were then remixed, ground, and processed through a scanning monochromator. Calibration equations for percent alfalfa were chosen using statistical analysis, Random subsets of samples were selected for validation of calibration equations using R2, bias, and standard error of performance (SEP). Broad‐based calibration equations required as little as 200 samples (approximately 5%) to accurately predict botanical composition of alfalfa/ryegrass mixtures with R2 of 0.95, SEP of 6.5%, and bias of −0.3%. Calibration equations generated from each of the four studies separately only marginally improved SEP and slightly increased bias. When botanical composition was estimated on samples from locations not included in the calibration data set, large increases in SEP and bias were observed. Errors associated with NIRS estimations were often one‐half as large as the experimental and sampling errors.
Leaf Appearance Rates of Two Winter Wheat Cultivars under High Carbon Dioxide Conditions
Authors: Boone M. Y. L. , Rickman R. W. , Whisler F. D.
Published: July 2010

The mechanisms describing leaf appearance and tillering are vital to the modeling of wheat canopy development. How these two factors will be affected by increasing global atmospheric [CO2] in cool or warm climates is not fully understood. Two southeastern USA adapted wheat (Triticum aestivum, L.) cultivars, Coker 762 and Stacy, were grown under nearly nonlimiting conditions including elevated [CO2] (600 μL L−1) and under six air temperature regimes (ranging from 4/−1 to 18/7 °C d/night and progressively increasing to 16/4 to 29/18 °C d/night during the season) to observe leaf and tiller appearance rates and to compare tillering rates to those predicted by the Fibonacci series as approximated by Binet's equation. Both cultivars exhibited an abrupt one‐time change in their phyllochron interval for all six temperatures. This change occurred just prior to double ridge formation. The vegetative growth phase phyllochron interval of the two cultivars was significantly different only in the (21/10 °C) temperature treatment. In the two lowest temperature treatments (16/4 and 18/7 °C), the cultivars differed in phyllochron interval during the reproductive growth phase. The tillering rate of wheat followed closely the theoretical development predicted by Binet's equation during the vegetative phase of development.