bluuebunny/crossref_metadata_2025 huggingface dataset:
Development and Yield of Hard Red Winter Wheats Under Semitropical Conditions1
Authors: Wiegand C. L. , Gerbermann A. H. , Cuellar J. A.
Published: July 2010

Winter wheat (Triticum aestivum L.) cultivars were planted in the field on 11 and 28 Nov. 1977 and on 8 and 24 Jan. 1979 near Weslaco, Texas, at 26° 13' N Lat to document their developmental responses and yield under conditions of temperature and photoperiod that limit vernalization, floral initiation, and grain filling. Such studies help define controlling factors in range of adaptation and necessary inputs for growth models to have wide geographic applicability. For both season's plantings on Hidalgo sandy clay loam (Typic Haplustroll), Feekes‐Large phenological stages were observed and inflorescence development was determined by dissecting sample plants removed from the plots. The number of fully expanded leaves and green leaves per main culm and the number of secondary tillers were also recorded for tagged plants pf the 28 November planting on 33 dates during the growing season. Head length, heads/m2, kernels/head, mg/kernel, and grain weight/m2 were determined from five row segments totaling 1 m2 in each planting.

The 1977 plantings vernalized naturally on 800 cumulative hours of ambient temperature between 0 and 10 C by 4 March, but they remained vegetative during the short days of winter and produced leaves linearly in response to cumulative heat units. Floral differentation (‘double ridge’ stage), stem elongation (first node), and anthesis varied about a week among cultivars. Average yield components across all cultivars were: 1977‐78 season— 442 heads/m2, 11.2 kernels/head, and 8.0 mg/kernel, and 1978‐79 season—436 heads/m2, 14.6 kernels/head, and 22.5 mg/kernel. Grain yield (oven‐dry basis) averaged 48.8 g/m2 or about one‐eight commercial levels for the 1977‐78 season, and 141 g/m2 for the 1978‐79 season. Duration of grain‐filling (anthesis to mealy ripeness) averaged 17 and 20 days for the respective seasons. Within the temperature range 15 to 27 C, the grain‐filling period (data include three spring wheats also studied) for the 1977‐78 data was shortened by 3.4 days for each 1 C rise in average daily temperature.

Evidently insufficient photoperiod for floral initiation is more restrictive on winter wheat production under semitropical conditions than the vernalization requirement. In both seasons nonvernalized wheat headed even when planted as late as 24 January, but regardless of planting date or preplant vernalization it did not floral initiate until March. Consequently, grain filling occurred under a temperature regime that severely shortened its duration, and small kernels were produced. Because of rapid leaf production during mild winter days of the semitropics, wheat could be an excellent winter forage if leaf rust were controlled.
Response of Ratooning Grain Sorghum to Nitrogen Fertilizer and Insecticides1
Authors: Touchton J. T. , Martin P. B.
Published: July 2010

Interest in production of two grain crops on the same land during a single warm season in the subtropical regions has increased rapidly during the past few years. Presently, grain sorghum is being ratooned for a second grain crop but production practices for the ratooned crop are not well defiled. To evaluate the effects of fertilizer N and insecticides on the production of ratooning grain sorghum (Sorghum bicolor (L.) Moench), field studies were conducted for 2 years on a Greenville soil (Rhodic Paleudult). Nitrogen (0 to 157 kg/ha) was applied immediately after the first crop was harvested and a combination of insecticides was applied just prior to heading and during the early bloom stage. Nitrogen uptake, grain size, grain yield, and insect population counts were used to determine treatment effects.

Leaf N increased with increasing N application rates in 1977. Grain yield did not increase when applied N exceeded 112 kg/ha. Average weight per hundred seed for all treatments was 1.6 g compared with an average of 2.7 g for the planted seed. Insect infestation was high in 1977 and yields of the ratooned crops (averaged over N rates) were 2,210 and 1,383 kg/ha for the insecticidetreated and untreated areas, respectively.

In 1978, leaf K ranged from 1.4 to 2.0% and increased with increasing N rates up to 67 kg/ha. Weight per hundred seed averaged 2.22 and 2.91 g for the insecticidetreated and untreated areas, respectively, but did not respond to applied N. Although insect monitoring revealed no evidence of high densities of phytophagous insects, grain yield averaged 67% higher when insecticides were applied. Yield increased with increasing N rates up to 67 kg/ha in the insecticide‐treated area but there was no response to applied N when insecticides were not applied. When averaged over N rates, yield from the insecticide‐treated and untreated area in 1978 was 3,136 and 1,882 kg/ha, respectively. Total grain yield from the planted and ratooned crop (with optimum N and insecticides) in 1978 was 9,847 kg/ha. Data from this study suggest that 67 kg/ha of N fertilizer is sufficient for ratooned grain sorghum; the applied N will be economical if a well managed insecticide program is followed.
Guidelines for Measuring and Reporting Environmental Factors in Growth Chambers
Authors: Spomer L. Art
Published: July 2010

Guidelines for measuring and reporting environmental factors in growth chamber and other controlled environment studies of plant growth are listed. These guidelines were developed by a committee1 of researchers concerned with the use of controlled environment facilities for plant research. Adoption of these standardized guidelines should improve the quality of plant research done in such facilities.
Grass Tetany Potential of Tall Fescue Infected with Epichloe typhina1
Authors: Odom J. W. , Haaland R. L. , Hoveland C. S. , Clark E. M.
Published: July 2010

The plant parasitic fungus Epichloe typhina (Pers.) Tul. has been implicated as the causal organism of bovine fescue toxicity, a syndrome of cattle grazing tall fescue (Festuca arundinacea Schreb.). Since the fungus obtains its energy from the tall fescue plants, a greenhouse study was designed to determine the effect of fungal infection on plant uptake of those elements associated with grass tetany: Ca, Mg, and K. Epichloe typhina infection did not affect the mineral content, or, therefore, the grass tetany potential of tall fescue.
Amino Acid Composition of Grain Protein of Maize Grown with and without Pesticides and Standard Commercial Fertilizers1
Authors: Wolfson Jane L. , Shearer Georgia
Published: July 2010

Increases in the price of agricultural chemicals and uncertain supplies are likely to cause a reduction of pesticide and fertilizer use in the future. Therefore, it is of interest to compare yields and quality of crops grown under present conventional practice with those grown at the lower limit of chemical intensiveness. In this paper, we report measurements of the amino acid composition of protein from maize (Zea mays L.) grain raised on 14 pairs of fields which did (conventional) and which did not (organic) receive pesticides and standard commercial fertilizers. The pairs of fields were matched for location, cultivar, planting date, and soil type.

When expressed as percent of grain protein, five amino acids were at significantly higher concentration in organic grain and three were at significantly higher concentration in conventional grain. However, because of the lower protein concentration in the organic maize grain, most of the amino acids in conventional grain had significantly higher concentrations, when expressed as percent of total grain weight. The latter fact is more important from the standpoint of livestock feeding.

Differences in yield, protein concentration, and amino acid composition between organic and conventional maize were qualitatively similar to reported differences between N‐fertilized and non‐N‐fertilized maize. At least part of the difference between organic and conventional maize is consistent with a greater accumulation of zein in conventionally raised maize.

Results presented in this paper suggest that organic maize yields could be increased by N application. Since the yield difference was small, the N limitation should be overcome by modest rates of application.
Beltwide Evaluation of Fungicides Applied to Acid‐Delinted Cottonseed1
Authors: Minton Earl B. , Quisenberry J. E.
Published: July 2010

A fungicide applied to cottonseed (Gossypium hirsutum L.) has been suspected to protect seed and seedlings in one region of the Cotton Belt but not necessarily in other regions. Fungicides applied to cottonseed have been evaluated in each cotton producing state through the years. The objective of this study was to compare the performance of various fungicides applied to acid‐delinted cottonseed at many locations across the U.S. Cotton Belt to determine whether locations could be delineated for refinement of the program. Fungicides applied to sugplots of a given lot of acid‐delinted cottonseed each year were evaluated at several locations for 2 years. Combined analyses of variance of final stand were used to determine the effects of years, locations, fungicide seed treatments, and the interactions of these primary effects on stand establishments across the U.S. Cotton Belt. Significant differences were not detected among locations, fungicides, or interactions of seed treatments ✕ locations. The lack of statistically significant differences demonstrated that the effectiveness of fungicides applied to acid‐delinted cottonseed can be determined with fewer test locations.
Drought Effects on the N2‐Fixing (Acetylene Reducing) Ability of Vetch and Sweetclover Growing under Saline Conditions1
Authors: Walsh J. F. , Skujins J.
Published: July 2010

Drought and salinity are prominent environmental stresses which limit N2 fixation by legumes. Both drought stress and salinity stress induce physiological adjustments which allow plants to compensate for decreasing available water, although the mechanisms may not be the same for the two types of stress. This study was designed to compare the effects of drought stress on N2 fixation for plants in nonsaline and saline soils.

The acetylene reducing (N2‐fixing) activity of hairy vetch (Vicia villosa Benth) and yellow sweetclover [Melilotus officinalis (L.) Lam.] was determined after repeated cycles of drying and rewetting. Soil in pots was artificially salinized by adding NaCl and CaCl2 to achieve nominal electrical conductivity values of 0 (control), 4, 8, and 12 mmhos/cm. Day temperatures ranged between 24 and 30 C and night temperatures between 15 and 18 C. Soil water potential was measured by using thermocouple psychrometers. Drought was induced by withholding water and plants were rewatered when soil water potentials at the 6 cm depth dropped below −45 bars. Both vetch and sweetclover had decreasing acetylene reduction rates with increasing salinity levels when water was not limiting. After two drying and rewetting cycles, all plants had decreased levels of acetylene reducing activity regardless of salinity level. However, vetch plants in salinized soils retained a greater proportion of their pre‐drought acetylene reducing activity than plants in non‐saline soil. Sweetclover plants had little acetylene reducing activity after two drought cycles and vetch plants lost most activity after five drought cycles.
Cutting Managment of the Tropical Legume American Jointvetch1
Authors: Mislevy P. , Kalmbacher R. S. , Martin F. G.
Published: July 2010

The establishment and production of short‐lived perennial legumes like ‘American’ jointvetch (Aeschynomene americana L.) has been more satisfactory than that of perennials in Florida. Since jointvetch can develop into a poorly digestible forage which is rejected by animals, a harvest frequency and cutting height study was conducted on a sandy, siliceous, Typic Haplaquod (Ona fine sand). Jointvetch was cut when plants reached initial heights of 30, 60, and 90 cm, and the plants were cut to leave 8 and 18‐cm stubble heights. Regrowth was cut when plants reached 30, 60, or 90 cm. The plant height at initial harvest was most important in determining the total seasonal yield. Plants cut at 30 cm initially had 60 cm regrowth with 200% more tillers than the initial, but plants cut initially at 60 or 90 cm resulted in regrowth with fewer tillers than the initial harvest. Cutting the initial harvest when plants were 30 cm tall followed by cutting regrowth at 90 cm or cutting the initial and continually recutting at 30 cm resulted in highest dry matter yield and quality. Both crude protein and in vitro organic matter digestion (IVOMD) decreased with increasing regrowth height and more importantly, increasing initial harvest height. Protein and IVOMD of plants cut at an 8‐cm stubble averaged 15.5 and 59.2%, respectively. However, protein (17.4%) and IVOMD (63.1%) were much higher when plants were cut at an 18‐cm stubble. These data indicated that the largest yield and highest quality may be obtained by cutting or grazing jointvetch at the shortest practical initial height (60‐cm initial; 8‐cm stubble). This will allow for multiple harvests of quality forage.
Influence of Herbicides and Tillage on Sweet Corn Double Cropped After Peas1
Authors: Ndon Bassey A. , Harvey R. G.
Published: July 2010

Dinitroaniline herbicides are widely used for production of canning peas (Pisum sativum L.). These are residual herbicides and the effects of residues has been long recognized to be influenced by tillage. Careful evaluation of these compounds was thus needed before growers could consider growing sweet corn (Zea mays L.) following peas in a double cropping system. Peas were therefore established in a field study (Typic Argindoll finesilty, mixed mesic soil), using various dinitroaniline herbicides for weed control. After pea harvest, half the area was plowed and planted to sweet corn, and the remaining area was planted with a minimum tillage method to the same crop. Observations were made of weed growth and pea and sweet corn performance.

The tillage and planting systems alone influenced both weeds and sweet corn. Giant foxtail (Seteria faberi Herrm.) and velvetleaf (Abutilon theophrasti Medic.) populations were 63 and 87% higher, respectively, in the sweet corn check plots planted with conventional tillage than when planted minimum till. Sweet com population and yield were 15.6 and 14.4% higher, respectively, with conventional tillage than with minimum tillage.

The dinitroaniline herbicides had a significant impact on the sweet corn crop only when it was planted using the minimum till system. Dinitramine [N4,N4‐diethyl‐α,α,α‐trifluoro‐3,5‐dinitrotoluene‐2,4‐diamine], fluchloralin [N‐(2‐chloro‐ethyl)‐2,6‐dinitro‐N‐propyl‐4‐(trifluoro methyl)aniline], pendimethalin [N‐(l‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine], trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine), and a combination of oryzalin [3,5‐dinitro‐N4, N4‐dipropyl‐sulfanilamide] plus trifluralin residues were effective in reducing giant foxtail and velvetleaf populations in sweet corn. Ethalfluralin [N‐l‐ethyl‐N‐(2‐methyl‐2‐propenyl)‐2,6‐dinitro‐4‐(trifluoromethyl)benzenamine] was effective in controlling the velvetleaf population. Trifluralin residues caused the greatest carryover injury to sweet corn stands and the intensity of injury increased with higher application rates. Only fluchloralin, ethalfluralin, and trifluralin at 0.84, 0.84, and 0.42 kg/ha, respectively, did not cause sweet corn injury. The best sweet corn yields were obtained following treatments of dinitramine, ethalfluralin, and fluchloralin.
Recovery of Introduced Rhizobium japonicum Strains by Soybean Genotypes1
Authors: Kvien C. S. , Ham G. E. , Lambert J. W.
Published: July 2010

Soybean [Glycine max (L.) Merr.] seed yields and seed protein percentages have been increased significantly with inoculation where soybeans were not grown previously. However, when the soil contains Rhizobium japonicum from previous inoculation, significant differences in seed yield are usually not obtained from inoculation. Generally, about 5 to 10% of the nodules are produced by the inoculant applied to the seed with the other 90 to 95% of the nodules produced by R. japonicum already present in the soil. Field studies were used to identify soybean genotype‐R. japonicum strain combinations which might enhance soybean yields through more effective biological N2 fixation. Soil types in the experiments were Waukegan silt loam (Typic Hapludoll), Nicollet silty clay loam (Aquic Hapludoll) and Webster silty clay loam (Typic Haplaquoll). The first approach involved screening soybean genotypes for their ability to recover introduced R. japonicum strains from a mixed indigenous soil population. The second approach involved evaluating over 1,600 soybean lines for their degree of nodulation (relative to commonly‐grown cultivars) with the indigenous strains of R. japonicum. Twenty‐four soybean lines were selected from the 1,600 for further study in yield trials. Some lines were better nodulated than the commonly‐grown cultivars while other lines were very poorly nodulated. High recoveries of inoculant strains usually produced positive yield responses. Two of the tested soybean lines (PI 358.319 and PI 70.017) recovered an introduced strain (R. japonicum USDA 110) at enhanced levels (as high as 55% of the plant nodules were from the inoculated strain) and responded with increased seed yield at both test locations. The seed yields of PI 358.319 and PI 70.017 were increased by as much as 437 and 459 kg/ha, respectively, while the seed yields of commonlygrown cultivars were not increased. Recovery of inoculant strains was found to be independent of the soybean genotype's ability to nodulate with the indigenous R. japonicum strains.

Generalizations on the recovery and effectiveness of introduced R. japonicum strains could not be made based on the soybean line's ability to nodulate with the indigenous R. japonicum strains. Each soybean genotype must be examined individually for nodulation with indigeous R. japonicum, for recovery of introduced strains, and for the general effectiveness with introduced strains to increase seed yields.
Methods and Rates of Applied Manganese for Soybeans1
Authors: Boswell F. C. , Ohki K. , Parker M. B. , Shuman L. M. , Wilson D. O.
Published: July 2010

Soybeans [Glycine max (L.) Merr.] have responded to supplemental Mn fertilizer on high water table soils when limed to soil pH levels near neutrality, but the effect of method and rate of Mn application under these conditions is not well understood. In a 3‐year study (1975–1977) on an Olustee‐Leefield sand (Ultic Haplaquod‐Arenic Plinthaquic Paleudult), four application methods (broadcast preplant, row at planting, sidedress, and broadcast preplant plus foliar spray), at four rates (0, 5.6, 11.2, and 22.4 kg/ha) of Mn were employed to evaluate their effects on yield, leaf blade concentrations, seed Mn levels, and extractable soil Mn levels. A 239% yield increase was obtained in 1977 with 11.2 kg Mn/ha compared to no applied Mn. Yield increases due to applied Mn were not obtained in 1975 and 1976, although visual deficiencies were evident early in the growing season every year. Yield increases were related to seed weight for the various Mn rates. Methods of Mn application did not influence yields in any given year. However, the row at planting application may have produced toxic effects since there were visual toxicity symptoms and trends of decreased yields each year. Leaf tissue sampled at the R‐2 growth stage indicated the Mn level should be greater than 15 ppm for maximum yields with broadcast application and the critical Mn level in the seed is 16 ppm. In this study, correlation and regression analyses indicated the seed Mn levels were better related to yield than leaf blade Mn levels. Double acid extractable soil Ma increased from 1975 through 1977 while DTPA extractable Mn showed a slight decrease. Both methods were well related to applied Mn rates. These data indicate that applied Mn rates influence soybean yields, soil Mn, tissue Mn, and seed Mn concentrations more than methods of Mn application.
Comparative DRIS and Crop Log Diagnosis of Sugarcane Tissue Analyses1
Authors: Jones C. A. , Bowen J. E.
Published: July 2010

The Crop Log system of sugarcane (Saccharum spp. hybrid) tissue analysis is a critical concentration approach which is widely used for the diagnosis of nutrient deficiencies and imbalances in the Hawaii sugar industry. Recent studies conducted elsewhere suggest that the Diagnosis and Recommendation Integrated System (DRIS), which utilizes ratios of tissue nutrient concentrations rather than the concentrations themselves, consistently gives a lower percentage of incorrect diagnoses of nutrient deficiencies and imbalances than critical concentration approaches. In these studies, it is often unclear whether the higher accuracy of the DRIS approach was due to inherent advantages of the DRIS approach or to local calibration of the system. The objective of this study was to compare the diagnostic accuracy of the conventional Crop Log approach, a locally calibrated Crop Log approach, and DRIS. In an analysis of 28 past fertilizer experiments on the island of Hawaii the locally calibrated Crop Log and DRIS approaches gave 3 and 5% fewer incorrect diagnoses, respectively, than the conventional Crop Log approach. The results suggest that the DRIS approach can provide slightly more accurate diagnoses of nutrient deficiencies than the conventional Crop Log approach.
Interrelation in Common Winter Wheat of Cold Hardiness and Emergence in Dry Soils1
Authors: Morrison K. J. , Patterson F. L. , Bula R. J. , Nyquist W. E.
Published: July 2010

Rapid emergence is important for wheat (Triticum aestivum L. em Thell.) establishment in semiarid winter wheat areas. Ability to germinate and emerge under low moisture stress may involve physiological processes in common with those of cold hardiness of young seedlings.

A germinated‐seed technique was used to determine whether a relationship exists between cold hardiness of very young plants and emergence ability of winter wheat under moisture stress. Four parental cultivars and nine populations from crosses among them were used to evaluate these relationships. Cold hardiness measured by percent survival and emergencerate index had relatively high heritability values. Phenotypic and genotypic correlation coefficients between measures of cold hardiness and emergence ability suggest that these responses in winter wheat are controlled in small part by the same genetic system.
Shade and N Effects on Tall Fescue Production and Quality1
Authors: Stritzke J. F. , McMurphy W. E.
Published: July 2010

Tall fescue (Festuca arundinacea Schreb) has been established on a number of areas in eastern Oklahoma, western Arkansas, and southeastern Missouri after the brush has been controlled. There have been cattle deaths attributed to nitrate‐nitrogen (NO3‐N) toxicity on these converted areas and concern that the shade from the standing brush was contributing to the problem. A 6‐year study was conducted at the western edge of the Ouachita Highland resource on soils of the Hector‐Hartsells association (Lithic Dystrochrept and Typic Hapludults) to determine what effect N fertilizer and shade would have on tall fescue forage production, crude protein, and NO3‐N concentration. The brush had been controlled with 2,4,5‐T [(2,4,5‐trichlorophenoxy)acetic acid] in 1970 and the area converted to tall fescue. February application of N fertilizer increased forage production with the greatest increase occurring with the first 50 kg/ha of applied N. Shade effect from standing dead brush was insignificant on forage production and NO3‐N concentration, but 80% shade from Saran shade cloth for 6 days increased NO3‐N concentration from 1,200 to 4,200 ppm in plots receiving 50 kg/ha of N. Nitrogen fertilizer increased NO3‐N concentration of the forage in March of both years NO3‐N was evaluated with a high of 7,500 ppm occurring for the 100 kg/ha applications of N. However, by April of both years the NO3‐ N levels in the forage from all plots were below the potentially toxic level of 2,100 ppm for cattle.

Standing dead brush had a minimum effect on tall fescue production, percentage crude protein, and NO3‐N concentration so would not need to be removed from brush converted areas. The NO3‐N concentration of N fertilized plots was often above the toxic level of 2,100 ppm in March so precautions need to be exercised in grazing N fertilized tall fescue in March.
Plant Resistance to Water Flow in Field Soybeans: I. Non‐Limiting Soil Moisture1
Authors: Jones J. W. , Zur K. J. , Boote K. J. , Hammond L. C.
Published: July 2010

Resistances to water flow from the soil to plant leaves determines the ability of plants to maintain favorable water conditions. Predictions of plant water relations and transpiration require estimates of resistances to water flow in the soil and in the plant. The purpose of this field experiment was to determine plant resistance to water flow under field conditions during two periods of soybean [Glycine max (L.) Merr.] growth. The experiment was conducted on Arredondo fine sand (hypothermic, coated Typic Quartzipsamment). Root depth distributions were measured during each growth period and soil water potential distributions were measured daily. Every other day, during the periods: 4 to 16 May (Exp. I) and 30 May to 7 June (Exp. II), hourly measurements of leaf water potential and transpiration were used to calculate plant resistance using Ohm's law analogy. Daily plant resistance was calculated using midday leaf water potential and total integrated transpiration for each day. Calculated plant resistance increased with transpiration flux in a non‐linear relationship. However, when plant resistance values for quasi‐steady state conditions during midday hours were examined, they averaged 940 MPa h/cm2 for the first experiment, independent of transpiration flux over a range of 0.02 to 0.05 cm/h. Plant resistance values increased with time and averaged 2,360 MPa h/cm2 for quasi‐steady state conditions in the second experiment. Plant resistance values calculated on a daily basis averaged 200 and 300 MPa‐day/cm2 for the first and second experiments, respectively, 3 to 5 times higher than plant resistance values based on hourly measurements. Under natural conditions, the plant is seldom at steady state and random or average measurements of leaf water potential do not represent the true driving force for water transport through this complex system.
Total Resistance to Water Flow in Field Soybeans: II. Limiting Soil Moisture1
Authors: Zur B. , Jones J. W. , Boote K. J , Hammond L. C.
Published: July 2010

Experiments were conducted to determine the total (soil plus plant) resistance to water flow through field grown soybeans [Glycine max (L.) Merr.] subjected to two drying cycles during pod addition and early pod fill (4 to 16 May) and mid‐to‐late pod fill (30 May to 7 June). Root length density distributions with depth were measured during each drying cycle and soil water potential distributions were measured daily. The experiment was.conducted in the field on Arredondo fine sand (hypothermic, coated Typic Quartzipsamments). Transpiration flux and leaf water potential measured hourly every 2 days during each drying cycle were used with daily measurements of soil water potential to calculate total resistance. Midday transpiration rates decreased relative to transpiration rates of irrigated plots starting 8 and 5 days after irrigation for the first and second drying cycles, respectively, when average soil water potential was −0.04 MPa. The increase in total resistance which corresponds to the decrease in transpiration flux was attributed to increased soil resistance. However, calculated soil resistances based on experimental results were four to six orders of magnitude higher than theoretical calculations of the bulk soil resistances based on the Gardner (1960) model. Calculations of water potential at the root surface during drying conditions indicate that unsaturated hydraulic conductivity of soil adjacent to the root may be several orders of magnitude lower than that of the bulk soil and could explain the observed reduction in the transpiration flux.
Baby Bear's Dilemma: A Statistical Tale1
Authors: Carmer S. G. , Walker W. M.
Published: July 2010

An allegorical and satirical, but also, we hope an accurate and humorous expository look at the problem researchers face in choosing a pairwise multiple comparisons procedure for detecting differences among treatment means. The primary objective is to present, from several points of view, some of the arguments and resulting confusion surrounding the use of the least significant difference vis‐a‐vis Tukey's w procedure or honest significant difference, Duncan's Multiple Range Test, and the Waller‐Duncan Bayesian k‐ratio t test. Particular emphasis is placed on demonstrating that the concept of comparisonwise error rate is considerably more logical, sound, and useful in pairwise multiple comparisons than the concept of experimentwise error rate. As a consequence, despite what researchers may have read in the statistical Literature or what they may have heard from statistical experts, the least significant difference is appropriate whenever a pairwise multiple comparisons procedure is in order.
Selecting Environmentally Analogous Areas for Agronomic Research Using Computer Graphics1
Authors: Ford G. L. , Nielsen G. A.
Published: July 2010

Test plots are the foundation of most modern agricultural research programs. Experimental sites are frequently selected without substantial knowledge of surrounding land having similar environmental characteristics to which results can be directly applied. Thus, transfer of research results from experimental sites to environmentally analogous areas cannot be accomplished systematically or efficiently. Computer graphics were used in a study of the Montana Agricultural Experiment Station system to determine the amount and distribution of land having environments similar to those of existing research centers and to assist in locating a new center. The computer graphic system internally overlays maps of data and then plots single variable or composite maps showing the desired combination of environmental variables. Identifying agriculturally similar land facilitates the location of areas with potential for particular crop varieties or soil management practices, and permits more effective extrapolation of research results from experimental plots to farms.
Cultural Factors Affecting Yield, Alkaloids, and Sugars of Close‐Grown Tobacco1
Authors: Campbell C. R. , Chaplin J. F. , Johnson W. H.
Published: July 2010

Investigations of close‐grown tobacco (Nicotiana tabacum L.) with plant populations below 136,400/ha have shown that yield is increased with increased plant number. Marked differences in the appearance of stalk grown over a range of plant populations suggest that there may be physical or chemical advantages for growing close‐grown tobacco at even higher populations. With the development of direct field seeding or completely mechanized transplanting techniques, production at such levels may be economically feasible.

The present study was conducted to determine the yield, alkaloid, and sugar concentrations of close‐grown tobacco produced at populations ranging from 98,840 to 296,520/ha.

‘Speight G‐28’ was grown in a close‐grown system in 1976 and 1977 at the Oxford Tobacco Research Station on a Helena loamy sand (clayey mixed, thermic, Aquic Hapludult). Treatments included factorial combinations of plant population (98,840, 148,260, 197,680, 296,52Oha), topping height (12, 16, and 20 leaves/plant), and N‐rate (168, 252, 336 kg/ha). Plants were harvested once‐over and yield, total alkaloids, and reducing sugars were determined for lamina, midrib, and stalk.

Whole‐plant yields increased with increased plant population, Nrate, and/or topping height but yields of individual plant parts responded differently. Midrib yield did not change with any of the treatments but lamina increased with increased population and topping height through 16 leaves. Stalk followed the same yield pattern as whole‐plant material and increased at a greater rate than lamina. Total alkaloids increased with higher N‐rate and lower topping height but decreased with increased population. Reducing sugars did not change with increased population or topping height but decreased with increased N.

Effects of plant population and topping height are more predictable than that of N‐rate which is greatly influenced by seasonal growing conditions. A maximum leaf canopy apparently exists for a given planting design and density. Increased plant number above this level results mostly in increased stalk yield. Production at high populations will therefore depend on the acceptability of significant amounts of stalk in the smoking material.
Accumulation and Distribution of P, Fe, Mn, and Zn by Selected Determinate Soybean Cultivars Grown With and Without Irrigation1
Authors: Karlen D. L. , Hunt P. G. , Matheny T. A.
Published: July 2010

Reports on accumulation and distribution of nutrients by determinate soybeans [Glycine max (L.) Merr.] when grown under field conditions have seldom included information about micronutrients or made comparisons among several cultivars grown with or without irrigation. To provide this information, we grew three or four determinate soybean cultivars with or without irrigation on a Norfolk loamy sand (fine‐loamy , siliceous thermic Typic Paleudults) during 1978 and 1979. Plant samples were collected periodically throughout the growing season to measure dry matter accumulation and distribution among the leaves, petioles, stems, and pods. Plant fractions were analyzed for P, Fe, Mn, and Zn. Total P accumulation reflected total dry matter production and was greater in plants which received irrigation during periods of water stress. The total P and Zn accumulation among cultivars was generally not significantly different, although the P and Zn concentrations in the cv. Ransom were frequently higher. The concentrations and accumulations of Fe and Mn were generally not influenced by cultivar. Irrigation appeared to enhance P diffusion to plant roots and increased P concentrations at some samplings, but it rarely influenced Fe, Mn, or Zn concentration or accumulation. Total P, Fe, Mn, and Zn accumulations were greater during 1979 due to earlier planting, a shorter period of drought, and more available soil water in the lower part of the profile. Accumulation of these nutrients reflected plant growth, but seed yields did not follow the same pattern. With irrigation, 1979 seed yields averaged 1.95 metric tonsha compared to average irrigated yields of 3.16 metric tons/ha in 1978. Nonirrigated yields averaged 1.72 and 1.62 metric tons/ha in 1978 and 1979, respectively. Seed yields did not appear to be limited by P or micronutrient accumulation. Also, for these determinate cultivars yields were not closely related to total dry matter production.
Planting Date Effects on Sunflower Head and Seed Development1
Authors: Unger Paul W. , Thompson Tommy E.
Published: July 2010

The effects of environmental conditions during sunflower (Helianthus annuus L.) seed development and maturation on the final oil percent of seed and composition of the oil have been studied extensively but little is known about the sequential changes that occur in seed and oil during seed development and maturation. A better understanding of these changes could lead to improved management of sunflower for seed and oil production. The objective of this study was to determine the influence of planting date on development and maturation of sunflower head and seed. Sunflower was planted in about 2‐week intervals from 23 Mar. to 1 Aug. 1977 in field plots on Pullman clay loam (fine, mixed, thermic Torrertic Paleustolls). The experiment had a randomized block design with three replications. Plants that were at the same stage of development were marked at the ray flower stage. After anthesis, head samples were collected two or three tunes each week for about 30 days to determine head weight and diameter; seed dry matter percent, weight, and oil percent; and oleic and linoleic acid concentration of the oil. Separate seed samples were obtained from the outer, middle, and inner sections of the heads. Planting date, sampling date, and head position, as well as the interactions of these variables, significantly affected all dependent variables. Head diameter and fresh weight initially increased as the sunflower developed, then decreased due to head shrinkage and drying as the sunflower matured. Seed dry matter percent increased from the first to last sampling, but not at the same rate for all planting dates. Trendsfor seed weight were similar to those for dry matter. Total oil percent of seed increased from the first to the seventh sampling after which the differences were not significant. Seed from late plantings generally had a low oil percent, but seed from the ninth planting had an unexplained high oil percent. Oleic and linoleic acid concentrations of the oil decreased and increased, respectively, for later plantings. These trends also occurred with later samplings of sunflower planted on a given date. Based on multiple regressions, air temperature significantly influenced changes per day in seed oil percent, but not the oleic and linoleic acid concentration of the oil, during the intervals between samplings. During these intervals, changes in oleic and linoleic acid concentration of the oil were significantly influenced by total solar radiation and day length.
Corn Response to Irrigation on Surface‐Mined Land in Western Illinois1
Authors: Dunker R. E. , Jansen I. J. , Thorne M. D.
Published: July 2010

Moisture stress is one of the major yield limiting factors for row crops grown in the field on newly constructed mine soils. Response of corn (Zea mays L.) to irrigation on recently constructed mine soils in west‐central Illinois was studied over a two‐year period to determine the feasibility of utilizing water from surface‐mine lakes for irrigation of row‐crops on reclaimed land.

Two constructed soils, one with 45 cm of topsoil replaced on wheel spoil and one consisting of wheel spoil only, were studied. Both soils are Typic Udorthents. A lake formed in an abandoned mine incline supplied water to a solid‐set overhead revolving impact sprinkler system, randomly placed within each soil treatment which applied 3.8 cm of water each week to the irrigated treatment until physiological maturity.

Irrigation significantly increased corn yield in 1979 by 2,260 kg/ha for topsoil over wheel spoil and 2,630 kg/ha for wheel spoil only. The weather pattern in 1980 was distinctly different than in 1979 with severe stress during anthesis in 1980. Corn yield response to irrigation in 1980 ranged from 3,450 kg/ha to 6,030 kg/ha among soil treatments. Topsoil replacement resulted in significant yield increases with irrigation in both years. Without irrigation topsoil replacement resulted in a yield increase in 1979 and a yield reduction in 1980.

The data suggest that corn will perform well under favorable moisture conditions on newly constructed soils but is quite sensitive to moisture stress. Yields can be increased by irrigation using good quality water from surface mine lakes to alleviate this moisture stress.
Effect of Urea on Yield and Quality of Flue‐cured Tobacco1
Authors: Williams Linda MacKay , Miner G. S.
Published: July 2010

Flue‐cured tobacco (Nicotiana tabacum L.) can be sensitive to NH+4‐N in the soil, especially in the presence of CI−. Nitrogen sources such as (NH4)2SO4 and ammonium phosphates have depressed growth in the presence of strong, general‐purpose fumigants containing CI− that are sometimes used in tobacco culture, but little information is available for urea under similar conditions. Thus, urea was compared to NaNO3 in eight field experiments to evaluate the interactive effects of N sources and fumigants on the growth and chemical composition of flue‐cured tobacco. The various soils are listed in the Materials & Methods Section.

Urea and NaNO3 were applied singly or combined to provide four combinations of NO−3‐N and NH+4‐N in 1976 and 1977 and three combinations in 1978. Nitrogen was applied at 67 kg/ha except for an extra level of 112 kg/ha from urea in 1978. Fertilizers were banded in nonfumigated soil and soil treated with recommended rates of MoCap [O‐Ethyl S, S‐dipropyl phosphorodithioate] and Telone C‐17 [dichloropropylene, trichloronitromethane] in 1976 or Terr‐O‐Cide 30 [ethylene dibromide, trichloronitromethane] and Telone C‐17 in 1977 and 1978.

Yield and grade index were increased 26 and 20%, respectively, by urea compared to NaNO3 when excess rainfall occurred shortly after planting. Apparently, N from urea was still present as NH+4‐N and remained within the root zones while N from NaNO3 moved below the root zone. In a dry year, urea resulted in a 7% yield reduction compared to NaNO3 while grade indices were similar. Under conditions of adequate and well‐distributed rainfall, both N sources had similar effects on tobacco.

From 4 to 6 weeks were required to complete nitrification, depending on year and location, and the extent of nitrification at 2 and 4 weeks was reduced by both Terr‐O‐Cide 30 and Telone C‐17 compared to nonfumigated soil. Chloride concentrations in leaves increased until the 6th week and then abruptly declined, coinciding with the disappearance of NH+4‐N. Leaf CI− levels as high as 3.5% at 6 weeks were obtained for urea in the presence of Telone C‐17 but they were less than 0.5% in cured leaves at harvest, irrespective of N source or soil chemical treatment.
Nematicides and Fungicides Improve Legume Establishment1
Authors: Sheaffer C. C. , Rabas D. L. , Frosheiser F. I. , Nelson D. L.
Published: July 2010

Difficulties in establishing and maintaining legumes were observed on sandy soils (Aeric Haploquets) in northeastern Minnesota. Two field experiments were conducted to determine if nematicide and fungicide applications would increase establishment, yield, and persistence of alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.). In Exp. I, the nematicides phenamiphos [ethyl 4‐(methylthio)‐m‐tolyl isopropyl phosphoramidate] at 5.6 kg a.i./ha, aldoxycarb [2 methyl‐2(methylsulfonyl)propanal O‐methylamino carbonyl) oxime] at 8.9 kg a.i./ha, and carbofuran (2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl methylcarbamate) at 2.2 kg a.i./ha were applied immediately prior to legume seeding. In the seeding and following year, nematicide treatments increased legume yields and stands compared to the control. Carbofuran and phenamiphos were superior to aldoxycarb. Nematicides did not reduce soil nematode populations compared to the control.

In Exp. II, carbofuran at 2.2 kg a.i./ha alone or in combination with the fungicides metalaxyl [N‐2,6‐dimethylphenyl)‐N‐(methoxyacetyl)alanine methyl ester] at 2.2 kg a.i./ha and benomyl [methyl1‐(butylcarbamoyl)‐2‐benzimidazole carbamate] at 16 kg a.i./ha resulted in significantly greater alfalfa yields and populations than the control, benomyl, metalaxyl or metalaxyl‐benomyl treatments. Soil nematode populations were not affected by nematicide application; however, carbofuran and carbofuran‐metalaxyl and carbofuranbenomyl mixtures significantly reduced root lesion nematode [Pratylenchus penetrans (Cobb) Filipj. Schuur‐Stekh.] numbers recovered from alfalfa roots. The superiority of the carbofuran‐metalaxyl treatment in maintaining alfalfa populations compared to carbofuran or metalaxyl alone suggests a nematode‐fungus disease complex may be responsible for poor seedling establishment and yields of alfalfa.
Diurnal Relationship Between Evapotranspiration and Leaf Water Potential of Field‐Grown Soybeans
Authors: Reicosky D. C. , Kaspar T. C. , Taylor H. M.
Published: July 2010

Research is needed to describe the effect of management practices on plant water stress and water use efficiency. This study investigated the diurnal relationship between evapotranspiration (ET) and leaf water potential (Ψ1) for field grown soybeans [Glycine max (L.) Merr.] as affected by row spacing and irrigation on an Ida silt loam [fine, silty, mixed (calcareous) mesic family of Typic Udorthents]. ET and Ψ1 were determined in detail on 2 days in the 1979 growing cycle, one just preceding canopy closure (11 July) and the second at the midpod fill stage (1 August), Ψ1 was measured by using a pressure chamber technique, and ET was measured by using a portable chamber. On both days, the relationship between Ψ1 and ET was similar for both row‐spacing treatments. The nonirrigated treatments, however, demonstrated a slight hysteresis in the Ψ1‐ET relationship, whereas the irrigated treatments did not. The ET at a given Ψ1 was much greater on 1 August than on 11 July, probably because of an increase in soil evaporation caused by a recent rainfall and an increase in transpiration due to the increased leaf area index. The Ψ1‐ET relationship seemed to be affected more by irrigation than by row spacing. The simplified Ohm's Law analogy does not seem to adequately describe the relationship of plant water flux to resistance and potential difference under field conditions.
Potassium Fertilization Effects on Phomopsis Seed Infection, Seed Quality, and Yield of Soybeans1
Authors: Jeffers D. L. , Schmitthenner A. F. , Kroetz M. E.
Published: July 2010

Soybeans [Glycine max (L.) Merr.] are often damaged by the seedborne fungi Phomopsis sp. and Diaporthe phaseolorum (Cke. and Ell.) Sacc. in regions where the climate is warm and humid during and after maturation. Incidence of these fungi is sometimes decreased by soil application of K fertilizer to improve crop growth. This study was designed to determine if high levels of soil available K, or K fertilizer applications beyond that necessary to maximize yield, would have a significant effect on seed‐borne fungi and seed quality.

Soybeans were grown on Granby loamy fine sand (sandy, mixed, mesic Typic Haplaquoll), on Canfield silt loam (fine‐loamy, mixed, mesic Aquic Fragiudalf), and on Crosby silt loam (fine, mixed, mesic Aerie Ochraqualf). Potassium fertilizer was applied at various rates to establish a range of available K in soil. Potassium concentration of leaves closely paralleled K fertilizer treatments and the soil K levels. Seed was harvested from mature plants, and seed‐borne fungi were identified on samples cultured on potato‐dextrose agar. Phomopsis sp. was the most common fungus isolated from soybeans, ranging up to a 63% incidence. Diaporthe phaseolorum occurred with much less frequency, rarely exceeding a 10% incidence.

Potassium fertilization nearly always decreased moldy seed, but increased seed germination and yield somewhat less frequently. Where germination was increased by K fertilization, the incidence of Phomopsis sp. and D. phaseolorum nearly always remained unchanged. Thus, K fertilization usually does not influence Phomopsis sp. and D. phaseolorum infection of seed, but possibly limits fungal growth after infection has occurred. Fertilizer rates in excess of that necessary to maximize yield had little influence on germination or moldy seed.

Occurrence of Phomopsis sp. was greater in seeds from lower nodes than from upper nodes; whereas, the reverse was true of D. phaseolorum. Even though K deficiency symptoms occurred only on upper fruits and leaves, K fertilization decreased Phomopsis sp. 23 percentage points in lower seeds in contrast to 14 percentage points in upper seeds. Infection of seed by Phomopsis sp. within a plant does not appear to be related to K deficiency symptoms.