bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractResistances 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

AbstractExperiments 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

AbstractAn 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

AbstractTest 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

AbstractInvestigations 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

AbstractReports 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

AbstractThe 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

AbstractMoisture 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

AbstractFlue‐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

AbstractDifficulties 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

AbstractResearch 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

AbstractSoybeans [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.