bluuebunny/crossref_metadata_2025 huggingface dataset:
Vernonia anthelmintica: A Potential Seed Oil Source of Epoxy Acid. IV. Effects of Line, Harvest Date, and Seed Storage on Quantity and Quality of Oil1
Authors: White G. A. , Earle F. R.
Published: July 2010

Pre‐ and post‐frost harvested seeds of Vernonia anthelmintica (L.) Willd. lines PI 283729, VS63‐40, and VS65‐224 (pre‐frost only) were stored under continuous cold, room, and barn (ambient) conditions and sampled at 0, 48, and 96 weeks to determine the effects of storage on oil quantity and quality.

Harvest date did not affect oil content. For the prefrost harvest, oil content declined with storage time, especially under room and barn conditions, but the gradual reduction was not of practical significance. The oil percentages for seeds of PI 283729 (26.6%) and VS63‐40 (29.9%) significantly exceeded that of VS65‐224 (22.0%). Seed oils of the three lines did not differ in amounts of epoxy acid or free fatty acids. Epoxy acid content declined during the period from 0 to 48 weeks and then rose from 48 to 96 weeks. Time in storage affected epoxy acid content more than storage conditions. The level of free fatty acids remained essentially unchanged during the storage period. Good quality vernonia seeds can be stored for relatively long periods without a serious reduction in oil content or quality.

Poor quality oils with significantly lower levels of epoxy acid and higher levels of free fatty acids were obtained from the post‐frost harvest. The oil from PI 283729 seeds was of poorer quality than that from VS63‐40 seeds; the quality of both declined in storage at ambient temperatures.
Organochlorine Insecticide Residues in Soybean Plant Tops: Root vs. Vapor Sorption1
Authors: Beall M. Leroy , Nash Ralph G.
Published: July 2010

Soybeans were grown in specially constructed pots to determine the amount of residue contamination in plant tops from 20 ppm surface or subsurface soil‐applied 14C‐labeled p,p'‐DDT, dieldrin, endrin, or heptachlor. Regardless of the insecticide treatment, plant tops were contaminated by both root sorption and foliar sorption of vapors emanating from the soil. Root sorption was the major source of contamination by dieldrin, endrin, and heptachlor, though vapor sorption of dieldrin was nearly as great. Foliar contamination by vapor sorption of DDT residues was nearly seven times greater than for root sorption. Foliar contamination from vapor sorption of residues from all four insecticides was near the same order of magnitude, about 6.5 ppm plant dry weight, whereas contamination from root sorption from endrin was 38, heptachlor 21, dieldrin 11, and DDT 1 ppm.

Plant parts were assayed by several methods. Although residue concentrations were different for each insecticide, both the apparent plant degradation and mobility of the insecticide, or degradation products, were: DDT ≥ heptachlor > endrin > dieldrin where root sorption was the source of residue. One heptachlor degradation product, in addition to heptachlor epoxide, two endrin degradation products, and p,p'‐DDE and p,p'‐DDD were found.
Influence of Aluminum on Plant Growth and Mineral Nutrition of Potatoes1
Authors: Lee C. R.
Published: July 2010

Eight potato varieties were grown vegetatively in nutrient culture solutions to study the effect of aluminum on plant growth and mineral nutrition. The addition of 20 ppm Al to the growth medium reduced yields of plant tops and roots for all varieties. In other experiments, a differential tolerance to 1 to 5 ppm of Al was found among four potato varieties. Aluminum tolerance decreased among varieties in the order ‘Netted Gem’ > ‘Sebago’ > ‘Katahdin’ > ‘Green Mountain.’ P, Al, Mn, Fe, and Cu accumulated within plant roots grown in AI solutions while translocation of P to plant tops was depressed. Ca, Mg, and Zn absorption by plant roots was inhibited by AI. K absorption by plant roots was stimulated at low AI levels (1 to 2 ppm) but inhibited at high Al levels (5 to 10 ppm). Al tolerance among potato varieties may be related to the ability of plant roots to absorb Mg and K.
Interpreting the Rate of Change in Nitrate‐Nitrogen in Sugarbeet Petioles1
Authors: Carter J. N. , Jensen M. E. , Bosma S. M.
Published: July 2010

Nitrate‐nitrogen in sugarbeet petioles is used to evaluate current N status of sugarbeet crops. Since the NO3‐N changes rapidly during the season, better relationships are needed to interpret these data relative to sugarbeet N nutrition.

Sugarbeets (Beta vulgaris, L.) were grown at four N fertilization rates and two irrigation levels to determine the root yield, sucrose percentage, sucrose yield, and N uptake in relation to the NO3‐N concentration in the petioles. NO3‐N in beet petioles increased to a peak concentration and then decreased exponentially during the two growing seasons on all treatments. The exponential decrease after the peak enables prediction of the NO3‐N in the petioles during the remainder of the growing season. This rate of change approach can be used to predict N needs when adding supplemental N for sugarbeets and to characterize the N status of soil‐crop systems.
Effect of Rotations, Tillage Methods, and N Fertilization on Winter Wheat Production1
Authors: Tucker Billy B. , Cox M. B. , Eck H. V.
Published: July 2010

Winter wheat (Triticum aestivum L.) was grown continuously and in rotation with alfalfa (Medicago sativa L.) or grass on Pond Creek and Grant silt loams in the 64‐cm rainfall area of north central Oklahoma. Studies were conducted from 1956 through 1967. Stubble mulch and clean tillage were compared in continuous wheat and alfalfa‐wheat systems. The principal effect of alfalfa on wheat yield was to supply N. Wheat in rotation with alfalfa (3 years alfalfa, 3 years wheat) yielded 2,020 kg/ha, while continuous wheat fertilized annually with 45 kg N/ha yielded 2,180 kg/ha. Yields of wheat in a grass‐wheat rotation were inferior to those of continuous wheat plus N because of N deficiency.

Without N fertilizer, clean‐tilled continuous wheat outyielded stubble‐mulched continuous wheat by 23% (clean tilled: 1,790 kg/ha; stubble‐mulched: 1,460 kg/ha). With 45 kg N/ha, the advantage for clean tillage was reduced to about 8% (clean tilled: 2,160 kg/ha; stubble‐mulched: 2,000 kg/ha). The 45 kg/ha N fertilizer rate was sufficient for near maximum wheat yields under both clean and stubble‐mulch tillage.
Diurnal Variation in Nonstructural Carbohydrates, In Vitro Digestibility, and Leaf to Stem Ratio of Alfalfa1
Authors: Lechtenberg V. L. , Holt D. A. , Youngberg H. W.
Published: July 2010

Alfalfa (Medicago sativa L.) was sampled four times daily during first and second growths and eight times daily for three days during third growth in order to detect diurnal changes in carbohydrate constituency, in vitro digestibility, and leaf to stem ratio. The implications of these changes with regard to forage yield and nutritional value were considered.

Reducing sugars and sucrose were removed from freezedried, ground material by alcohol extraction. Starch in the residue was hydrolyzed by takadiastase. Ferricyanide, resorcinol, and phenol‐sulfuric acid procedures were used to quantitatively assay sugars in the extracts. Glucose and fructose percentages increased slightly but significantly from 6 AM to 12 N and declined to 6 PM in second and third growth alfalfa. About three times as much glucose as fructose was present. Sucrose comprised less than 3% of the dry matter, but varied considerably diurnally, generally increasing from 6 AM to 6 PM. Leaf starch increased from 10.2 to 20.3% of the dry matter during daylight hours, most of the increase occurring between 9 AM and 3 PM. Stem starch remained between 4 and 5% of the stem dry matter. In general, all nonstructural carbohydrates studied began to accumulate after 6 AM. Hexoses peaked first in leaves followed by sucrose and then starch. These were depleted in the same order in the afternoon and at night. Peak levels of glucose and sucrose occurred in stems later than in leaves. Leaf stem ratio increased from 1.1 to 1.5 between morning and evening and declined at night.

In vitro dry matter digestibility averaged 1.6% higher at 6 PM than at 6 AM.
Water Balance of a Seed Onion Field1
Authors: Goltz S. M. , Tanner C. B. , Millar A. A. , Lang A. R. G.
Published: July 2010

Transpiration, evaporation, and drainage from a sparsely populated onion field were measured separately by a method which should be applicable to many row crops. Transpiration computed from measured evapotranspiration, potential evaporation, and stomatal resistances agreed well with values calculated independently from raeasured stomatal resistance, air vapor pressure, plant‐temperature and wind. Transpiration was only about 20 percent of total evapotranspiration. When the population was increased threefold to near maximum commercial density, evapotranspiration increased only about 15 percent because as transpiration increased, evaporation decreased. The portion of transpiration accounted for by each plant part was 3 percent for umbels, 42 percent for leaves and 55 percent for scapes. Drainage from this sandy soil exceeded evapotranspiration.
Radicle Elongation of Pea Seedlings as Affected by Oxygen Concentration and Gradients between Shoot and Root1
Authors: Eavis B. W. , Taylor H. M. , Huck M. G.
Published: July 2010

Pea seedlings grown in divided gas‐tight containers were arranged so that O2 concentration of soil air around the radicles could be varied independently of that around the cotyledons and plumules. When the soil around the radicle tip contained 0.21 atm O2, no significant reduction in radicle elongation rate was observed until the gas mixture surrounding the cotyledons was reduced below 0.10 atm partial pressure. Even with O2 partial pressure at 0 around the cotyledons radicle elongation rate was 50% as high as that of the controls.

When O2 concentration around the radicle was varied, while that around the cotyledons remained at 0.21 atm, the radicle elongation rate at a given O2 level was markedly reduced. At zero O2 around the radicle elongation rate was only 20% of normal. It is suggested that a high diffusion impedance between internal gas channels and the relatively undifferentiated tissues near the root tip limits O2 supply to respiring tissue.
Tillage and Crop Residue Management During Seedbed Preparation for Continuous Spring Wheat1
Authors: Bond J. J. , Power J. F. , Willis W. O.
Published: July 2010

Field experiments were conducted to determine the effect of four tillage and crop residue management methods of seedbed preparation on continuous spring wheat (Triticum aestivum L.) receiving four rates of applied N. Effects of tillage and surface‐crop residues were separated by seedbed treatments of (a) conventional moldboard tillage, (b) conventional stubble mulch tillage, (c) moldboard tillage with part of the surface residue removed before and replaced after tillage, and (d) moldboard tillage with all surface residue removed before and replaced after tillage. Treatments were evaluated relative to grain yields, yield components, dry‐matter production, N uptake, soil nitrate content, soil temperature, plant water use and weed populations. for 3 of 4 years average grain yields (for all N rates) were 1,380, 1,060, 1,380, and 1,330 kg/ha for treatments a, b, c, and d, respectively. Yield reduction with stubble mulch tillage was related to poor weed control (primarily green foxtail) and not to the effects of surface residue per se. Use of fertilizer N failed to overcome yield reduction associated with stubble mulch tillage.
Effect of Nitrogen on Nodulation and Yield of Irrigated Soybeans1
Authors: Beard Benjamin H. , Hoover Richard M.
Published: July 2010

Wayne soybeans [Glycine max L. (Merrill)] were sown immediately after barley harvest in a 2 crop, 1‐year rotation experiment, to determine the effects of additions of nitrogen (as ammonium sulfate) on nodulation and yield. Treatments consisted of all combinations of: (i) barley straw residue (burned or shredded); (ii) timing of nitrogen application (before planting, at flowering or a combination); and, (iii) rates of application (0, 56, 112, 168 kg/ha of nitrogen) in a split‐split‐split design.

Nodule number per plant was linearly and inversely related to rate of nitrogen application. There were fewer nodules per plant if 56 kg/ha or more nitrogen was applied at planting time, but up to 112 kg/ha did not affect nodule numbers if applied at flowering. There appeared to be more nodules per plant on plots with the straw shredded, but the differences between shredding and burning the barley straw were not significant.

Even though plants on the 0 nitrogen plots were yellow‐green in early growth stages, there were no significant differences in yield due to straw treatment, timing, or rate of application of nitrogen.
Estimating Leaf Water Content by Reflectance Measurements1
Authors: Thomas J. R. , Namken L. N. , Oerther G. F. , Brown R. G.
Published: July 2010

Regression equations expressing reflectance of incidentlight from the upper (adaxial) surface of single leaves as a function of their relative turgidity and water content were developed. Reflectance at the 1.45‐ and 1.93‐µ water absorption bands was significantly related (p = 0.01) to the leaf relative turgidity or water content. However, because of variations in internal leaf structure associated with the availability of water during leaf development, the ability to predict the leaf water status from reflectance easurements was poor. With cotton (Gossypium hirsutum L.) the greatest change in reflectance occurs when the relative turgidity is below 70% and the leaves are visibly wilted. Within the relative turgidity range, 70 to 80%, reflectance changes are small and may not be definable for predictive purposes because of variation among leaves of field‐grown cotton caused by age differences and osmotic stresses.
Effects of Photoperiod, Light Intensity, and Temperature on Vegetative Growth, Flowering, and Seed Production in Cicer arietinum L.1
Authors: Sandhu S. S. , Hodges H. F.
Published: July 2010

Several diverse strains of Cicer arietinum L. were grown in growth chambers to study the effects of temperature, photoperiod, and light intensity on flowering and seed set. Plants were grown in 15, 22.5, and 30 C conditions at about 16 and 28 kilolux. Generally, plants in the high light intensity, 16‐hour photoperiod, and at 22.5 C, produced more flowers and seed than did other treatment combinations. Some strains produced flowers and set seed under short photoperiods and may have potential in breeding chickpea cultivars with wider environmental adaptability.
Estimating Leaf Area from Length Measurements for Hybrid Granex Onion1
Authors: Hoffman Glenn J.
Published: July 2010

A logarithmic linear relationship was found between leaf length and area for onion (Allium cepa L. ‘F‐l Hybrid Yellow Granex’) grown from seed in sunlit climate chambers with controlled temperature and humidity. Atmospheric relative humidity and root medium salinity had no effect on the relationship.
Estimating Nitrogen Content of Sweet Pepper Leaves by Reflectance Measurements1
Authors: Thomas J. R. , Oerther G. F.
Published: July 2010

A study was conducted to determine the feasibility of using spectrophotometrically measured diffuse light reflectance from top (adaxial) leaf surfaces of sweet pepper (Capsicum annum, L. var. ‘Yolo Wonder’) leaves to quickly estimate their N status. Reflectance was found to be inversely correlated (p = 0.01) with the leaf N content. Regression equations expressing reflectance as a function of leaf N content of greenhouse‐grown sweet peppers were used to estimate the N content of fieldgrown sweet peppers. The difference between Kjeldahldetermined and reflectance‐estimated N contents was less than 0.7%. The regression equation at the 550‐nm wavelength suggests that near the 4% N level a 1% change in reflectance would change the predicted N content by 0.2%. Results show that leaf reflectance can be used to quickly estimate the N status of sweet peppers.
Microclimate Modification by Slat‐fence Windbreaks1
Authors: Skidmore E. L. , Jacobs H. S. , Hagen L. J.
Published: July 2010

Abstarct

The influence of windbreaks on the microclimate has been widely studied, but more information is needed on the dynamics of wind barriers and how they modify the microclimate. Meteorological parameters were measured in the spatial vicinity of slat‐fence windbreaks of 0, 40, and 60% porosity to characterize microclimate modification by windbreaks of various porosities. The highest daytime air temperature, lowest nighttime air temperature, and generally the greatest vertical temperature differences all occurred in the area of lowest windspeed. However, lowest windspeeds occurred at different locations for the different porosity windbreaks. The water‐vapor‐pressure and vapor‐pressure differences between 40 and 5 cm above the crop surface were greatest at 2H leeward of the solid and 40‐percent‐open barriers throughout most of the daylight hours, whereas the vapor pressure at 2H leeward of the 60‐percent‐open barrier was similar to vapor pressure at other leeward positions. The vapor pressure was lower at 12H leeward of all barriers than in the open field

Bowen ratios indicated that evapotranspiration was greater in the sheltered area than in the open, contrary to our earlier findings of less evaporation from evaporimeters leeward of similar barriers. Possible explanations of this anomaly are lower potential evaporation in the shelter, leaving the plants more passive to transpiration, and unaccounted‐for horizontal divergence of sensible and latent heat in the sheltered area.
A Comparison of Ammonium and Nitrate Nitrogen for Cigar Wrapper Tobacco1
Authors: Rhoads F. M.
Published: July 2010

Five N fertilizer treatments ranging from all ammonium to all nitrate were applied in a randomized block experimental design, replicated four times, to cigar wrapper tobacco (Nicotiana tabacum L.). The NH4‐N to NO3‐N ratios were as follows 1:0, 3:1, 1:1, 1:3, and 0:1. A nitrification inhibitor was applied to control nitrification of NH4‐N, and black polyethylene mulch was placed on the soil surface to minimize leaching of NO3‐N.

The purpose of this experiment was to evaluate plant response of cigar wrapper tobacco to varying ratios of NH4‐N to NO3‐N.

Soil samples were taken at monthly intervals and tested for NO3‐N in order to check the effectiveness of the nitrification inhibitor. Yield, quality, and nutrient content of leaves were measured as indexes of plant response.

Nitrification appeared to be controlled satisfactorily by the inhibitor 2‐chloro‐6‐(trichloromethyl) pyridine. Cigar wrapper tobacco produced a higher yield and better quality with NO3N than with NH4‐N. Leaf concentrations of N, P, and Mg were affected very little by source of N; however, concentrations of leaf K and Ca increased as applied NO3‐N increased.
Patterns of Water Uptake and Root Distribution of Soybeans (Glycine max.) in the Presence of a Water Table1
Authors: Reicosky D. C. , Millington R. J. , Klute A. , Peters D. B.
Published: July 2010

The increasing importance of water use in crop production has demonstrated the need for integrated studies of water transport phenomena in the soil‐plant‐atmosphere system. A better understanding of the basic principles involved can lead to better management techniques for efficient water use. The purpose of this work was to measure water uptake patterns of soybeans (Glycine max.) and relate these to root distribution and water uptake per unit root length.

Water uptake in soil columns was analyzed using the flow equations for water movement in the soil, treating the root system as a macroscopic sink. The sink term represents the volume of water removed by the roots from a known volume of soil per unit time. Two soil columns were analyzed periodically for water content, root weight, and root length. Graphical evaluation of the water content and soil water flux distributions as a function of depth and time permitted determination of the sink term.

The results indicated that in the presence of a water table, water uptake was not necessarily related to root distribution and that a small amount of roots near the capillary fringe absorbed most of the water. The results also showed the combined importance and interaction of the hydraulic conductivity and the root distribution in determining the magnitude and the distribution of the sink term. Both of these factors limited the rate of uptake. As the plants grew, both increased water uptake per unit root length and increase in the length of roots contributed to meeting the rising daily rate of water use.
Accumulative Effects of Manure and N on Continuous Corn and Clay Soil. I. Growth, Yield, and Nutrient Uptake of Corn1
Authors: McIntosh J. L. , Varney K. E.
Published: July 2010

Four rates of manure and five rates of N were applied yearly in a factorial arrangement to a Panton clay soil (Typic Ochraqualf). Applications of 120 kg/ha of P and 90 kg/ha of K were made each year to all plots. The plots were planted to corn (Zea mays L.). The objectives of the study were to study the effects of continuous corn and manure and N treatments on the physical and chemical properties of the soil and on the growth, yield, and mineral composition of the corn plants over a period of at least 5 years. The results for the latter objective are reported in this paper.

During years of normal or less than normal rainfall (1965–67), manure application significantly increased yields of corn grain and stover. Averaged over all treatments of N, plots receiving 66 tons/ha of manure yielded 2.04 tons/ha more than no‐manure plots. This response is especially significant in that basic applications of P and K had been made and starter P used at planting each year. For these years, the first increment of N (56 kg/ha) increased yields on unmanured plots. Higher applications of N reduced yields. Where manure was applied, there was no significant response to N.

During relatively wet years (1968–69), manure had beneficial effect on corn growth and yield. The highest, or 66 ton/ha, manure application appeared to be detrimental, particularly where N had been applied. Nitrogen, on the other hand, significantly increased growth rate and yield of corn grain and stover at all levels of manure. For example, plots receiving 224 kg/ha of N yielded 5.51 tons/ha more than no‐N plots.

Manure treatments increased percentage K by as much as 0.30% in the corn ear leaves but decreased Ca and Mg. Manure had little effect on percentage N and P. In 1969, a wet year, manure reduced N from 2.72 to 2.44% when averaged over all treatments of N.

Chemical analysis of small plants showed the same trends as did analysis of ear leaves. Percentages of AI and Fe were high. But Al varied proportionally to applied N and inversely to manure. For all treatments of N, manure decreased Al from 139 to 85 ppm.

Manured plots were slightly but consistently higher in soil moisture. Small differences of about 1% were measured when the soil was near saturation (43% moisture). Differences of 2.5% were measured 1 week later when the soil was near 30% moisture.
Nutritional Influences on Cold Hardiness of St. Augustinegrass {Stenotaphrum secundatum)1
Authors: Reeves Sim A. , McBee George G.
Published: July 2010

The study was designed to determine the effect of late‐fall fertilization on winterkilling of St. Augustinegrass (Stenotaphrum secundatum). Data on which to base recommendations for late‐season fertilization of this grass in the South are inadequate. N, P, and K, and combinations of these were applied at different intervals at the rate of 1.47, 0.64, 1.23 kg/100 m2/mo, respectively, through December 1968 to plots in the College Station area. Plots to which N was applied in November and December showed the greatest topkill after each freeze, but were the first to resume growth when the temperature increased. Late application of N fertilizer, either in combination with P and K or separate, resulted in the grass remaining green longer in the fall and resuming growth faster in the spring. St. Augustinegrass lost the majority of its cold hardiness between 48 and 72 hours at 25 C under the conditions of this study.

Samples of tissues were collected to determine levels of the above‐named elements that were present. Chemical analysis of material collected before the first freeze showed higher N levels in the tissue under late N fertilization. A direct relationship appeared to exist between the tissue N level and levels of K and P. Where higher levels of tissue N were obtained, generally higher levels of P and K were also obtained.
Radial Propagation of Water Potential in Stems1
Authors: Molz Fred J. , Klepper Betty
Published: July 2010

Contraction and expansion of a cotton (Gossypium hirsutum L.) stem in response to a diurnal cycle of leaf water potential is described mathematically using a passive diffusion analysis. The domain of the problem is the stem phloem and associated tissues that are bounded on the outside by impervious bark and on the inside by the xylem that is assigned measured values of leaf water potential. Semiquantitative predictions are derived from numerical solutions of the linear radial diffusion equation, which yield phloem water potential as a function of space and time. Computations relating stem diameter, leaf water potential, and water flow between xylem and phloem fit experimental data. An apparent hysteresis in the stem diameter‐leaf water potential relationship is partly explained in terms of the physics of the diffusion process in the stem. This study offers possibilities for relating internal plant water status to measurable external quantities such as stem diameter and for developing a nondestructive technique for the determination of plant xylem water potential.
Compressibility of Turf as a Measure of Grass Growth and Thatch Development on Bermudagrass Greens1
Authors: Volk Gaylord M.
Published: July 2010

The object of this study was to develop a method for measuring the variation in compressibility of thatch on bermudagrass experimental and golf course greens and to evaluate the data as an indicator of grass growth and thatch development. A “thatchmeter” was designed to rapidly determine differences in compression between a bearing pressure of 7.3 g/cm2 and one of 570 g/cm2, the former less than that of a golf ball, and the latter, estimated from the weight of an average man. Regressions of compressibility on rate of grass growth and on thatch weight and depth were statistically significant (.001). Compressibility averaged between 6.1 and 11.5 mm per green for 24 golf greens under daily play. A 10‐reading average per plot or green can be obtained in 5 min and requires little professional supervision. The value of the procedure as a research tool is apparent, but specific ranges for acceptable playing quality of golf greens, between excessive hardness and excessive thatch, must be established individually for various grass varieties and environments.
Relationship Between the Content of Oil, Protein, and Sugar in Soybean Seed1
Authors: Hymowitz T. , Collins F. I. , Panczner J. , Walker W. M.
Published: July 2010

The oligosaccharides, raffinose and stachyose, have been implicated as causative factors for the flatulence and uncomfortable feeling often experienced after consuming products containing soybean [Glycine max (L.) Merrill] meal. Soybeans are primarily grown for their oil and protein content. Their value might be enhanced, however, if the oil and protein content remained high and the oligosaccharide content were lowered to make them more acceptable for human consumption.

Seeds of 60 selected lines from Maturity Groups 00 through IV were analyzed for protein, oil, total sugar, and individual sugar content. The ranges in values for oil, protein, total sugar, sucrose, raffinose, and stachyose were 14.5 to 23.0, 33.1 to 49.2, 5.6 to 10.9, 2.5 to 8.2, 0.1 to 0.9, and 1.4 to 4.1 g per 100 g seed respectively. Simple correlation analysis revealed that total sugar content and oil content in soybean seeds are positively associated, and each was negatively correlated with protein content. Sucrose and raffinose content were positively correlated with oil content, while stachyose content was positively associated with protein. Even though the correlation between certain sugars and oil or protein was statistically significant, considerable variation in total sugar content was not explained by the coefficient of determination (r2).
Nitrate Accumulation in Rye, Tall Fescue, and Bermudagrass as Affected by Nitrogen Fertilization1
Authors: Hojjati S. M. , Taylor T. H. , Templeton W. C.
Published: July 2010

This study was undertaken because of the need for additional information on nitrate accumulation in bermudagrass (Cynodon dactylon), tall fescue (Festuca arundinacea), and rye (Secale cereale) grown under comparable field conditions with varying rates of N fertilizer. Nitrogen levels employed were 0, 100, 200, 300, and 400 kg/ha/year, applied at several dressings throughout the growing season. Nitrate content in the herbage, determined by an enzymatic method, was studied during two growing seasons to ascertain whether potentially toxic levels are likely to occur under pasture conditions.

Provided that as much as 30 days elapsed between fertilization and harvest, NO3‐N levels were low at all rates of N from 0 through 67 kg/ha per application. Higher rates and/or shorter growth intervals frequently resulted in levels in the 700 to 2,000 ppm range or higher for rye and tall rescue, but not for bermudagrass.

Tall rescue accumulated more nitrate than did bermudagrass, both in association and when they were in pure stands. Rye also contained more nitrate than did bermudagrass. High nitrate content occurred only with high total‐N levels, but high total‐N did not always lead to excessive nitrate accumulation. The likelihood of high nitrate accumulation appears less likely with the passage of time after fertilization, indicating the need to appropriately harmonize fertilization and grazing schedules.
Oxygen Diffusion in the Soil‐Plant System VI. A Synopsis with Commentary1
Authors: Luxmoore R. J. , Stolzy L. H.
Published: July 2010

Three types of oxygen concentration profile within roots are described and related to conditions associated with these profiles. It is apparent that oxygen from soil aeration may be redistributed longitudinally toward the shoot or to the root tip in some situations.

The root respiratory properties and temperature influenced oxygen relations chiefly by effects on oxygen sink strength. Water film thickness around the root and root permeability to oxygen are additive resistances in the radial diffusion pathway, and as water film thickness decreased, root permeability had a more significant effect on oxygen relations. Roots with higher porosity had a higher oxygen concentration within the root and at the root tip and were less dependent on soil aeration. Potentially, modification of porosity may be a key factor in the design of root systems with high adaptability to a wide range of soil environmental conditions.

A model of root tip oxygen relations would be useful in giving a respiratory (energy) basis for relating root system development and root tip functions (cell division, elongation, salt uptake, and rhizosphere relations) to environmental factors.
Phosphorus Absorption by Sod‐Planted Corn (Zea mays L.) from Surface‐Applied Phosphorus1
Authors: Belcher Cluster R. , Ragland J. L.
Published: July 2010

The no‐till method of planting makes it difficult to incorporate fertilizer into the surface soil. The reason for doing the study was to determine if fertilizer placed on the surface of the soil was sufficiently available to corn (Zea mays L.) planted by the no‐till method in order to produce high yields. Because P is the least mobile of the major plant nutrients, it was chosen as the fertilizer variable in the study.

Corn was planted in a fescue sod killed with herbicides. Four rates of superphosphate (O, 56, 112, and 224 kg P/ha) were applied by two methods and the effects were measured in terms of corn grain yield and P content in the forage at four stages of plant development. All of the P was broadcast on the soil surface as one of the methods of application. The second method consisted of placing 28 kg P/ha into the soil near the seed and the remainder of the added P broadcast on the soil surface.

At 29 days after emergence dry matter accumulation was greater on plots receiving surface‐applied P than on plots receiving no P fertilizer. Although the percentage of P in the plants increased with increasing rates of applied P, maximum yields of dry matter were attained with 56 kg P/ha, as were yields of grain and stover.

Applying all of the P on the soil surface was equally effective to banding part of the P in the row and the remainder on the soil surface.

The data support the conclusion that under conditions of no‐till, corn planted in a killed sod can effectively absorb surface‐applied P. The P does not have to be incorporated into the soil in order to obtain high yields. It should be pointed out, however, that different results might have occurred had lower rates of P been used in the study. The lowest rate of added fertilizer (56 kg P/ha) produced grain yields just as great as the intermediate and the highest rates of added P.
Influence of Seed Size and Population on Yield and Other Characteristics of Soybean [Glycine Max (L.) Merr.]1
Authors: Fontes L. A. N. , Ohlrogge A. J.
Published: July 2010

The wide variations in plant productivity found in growth regulation field experiments and observations in growers' fields strongly suggested the need to evaluate seed size as a factor affecting productivity. In greenhouse and field experiments small and large soybean [Glycine max (L.) Merr.] seeds were planted in a systematic arrangement and also in a random distribution after being remixed with the residual intermediate size seeds (bulk) and the difference in their competitive capacities was assessed at different populations. The effects of interplant competition were great as the result of variation in initial seed size. Plants from large and small seeds appeared to be affected differently. The grain yields from large‐seeded plants increased, while those from small‐seeded plants decreased when grown interspersed. Varying the proportion of large to small seeds planted variously affected the grain yield per plant, stem diameter, and number of barren plants. When grown in a bulk population, large‐seeded plants had greater grain yield, more pods and branches per plant, and a smaller number of barren plants than small‐seeded plants. The number of pods per plant was by far the most important yield component influenced by seed size. Varieties ‘Amsoy’ and ‘Wayne’ performed similarly in relation to all characteristics studied except the weight per seed and number of branches per plant. Lodging and number of barren plants increased with population, while grain yield per plant, number of branches and pods per plant, and seed per pod varied inversely to population. This suggests that plant uniformity, obtained by uniform seed size, may be basic in achieving higher yield levels.
Interrelationships Among Plant Height, Number of Leaves, and Flowering Dates in Maize1
Authors: Cross H. Z. , Zuber M. S.
Published: July 2010

We evaluated the effect of different environments on the interrelationships among three morphological traits in corn (Zea mays L.) to see if relationships observed in limited environments held true over widely different growing conditions.

Data on number of days from planting to anthesis, plant height, and number of leaves per plot were obtained from 10 corn strains involving three greenhouse planting dates and 23 strains planted at 20 different locations ranging in latitude from 21° North (Mexico) and 49° North (Canada). The results indicated that although plant height at maturity was highly correlated with number of days from planting to anthesis in a limited range of environments, this relationship was very low when considered over a wider range of environments. In most cases, the relationship between number of leaves at maturity and number of days from planting to anthesis was even lower than that for plant height and number of days from planting to anthesis, especially when considered over wider environmental conditions. A significant correlation existed between plant height and number of leaves for most strains. The degree of relationship among the three characteristics varied among strains.
Field Response of Corn to ZnSO4 and Zn‐EDTA Placed with the Seed1
Authors: Martens D. C. , Hawkins G. W. , McCart G. D.
Published: July 2010

Zinc deficiency of corn (Zea mays L.) is generally corected by band or broadcast application of Zn. This field investigation was conducted on Westmoreland silty clay loam to determine if placement of a small amount of Zn in a band with seed would serve as an alternative procedure for correcting the deficiency. Treatments compared in the study included various levels, placements, and sources of Zn. Each method of Zn application under study increased corn grain yield as compared to the check. Corn grain yields were similar for 26.88 kg Zn/ha applied as broadcast ZnSO4 and for 0.34, 0.67, or 1.34 kg Zn/ha as Zn‐EDTA, or 1.34 kg Zn/ha as ZnSO4, applied in a band in contact with the seed. Higher corn grain yields were obtained with 26.88 kg Zn/ha as ZnSO4 broadcast and disked into the soil, than with 6.72 kg Zn/ha banded beside the row at seed depth. The levels of Zn banded with seed did not affect corn populations. This investigation indicates that band application of a small amount of Zn with seed could be used as a procedure for correcting Zn deficiency of corn. The procedure probably would be most applicable where it is desirable to minimize Zn accumulations in soil.
Performance of Alfalfa (Medicago sativa L.) Blends Consisting of Long‐ and Short‐Lived Varieties1
Authors: Jackobs J. A. , Miller D. A.
Published: July 2010

In the United States, blends (seed mixtures) of alfalfa (Medicago sativa L.) varieties were planted on approximately 8.75% of the acreage planted to alfalfa in 1969. Combinations of short‐lived highly productive varieties and long‐lived moderately productive varieties are assumed to be more productive than the long‐lived variety in the early years of the stand and to provide enough plants for an adequate stand after the short‐lived plants have died. To test these assumptions, blends containing a mixture of one long‐lived variety, ‘Vernal,’ and two short‐lived varieties, ‘Moapa’ and ‘Stride,’ were seeded at 4.5, 9.0, 13.5, and 18.0 kg/ha in April and August. Hay yields were determined through four harvest seasons. Stand counts were made in the 1st and 4th harvest years following the August planting.

Inclusion of Stride, a winter‐hardy, wilt‐susceptible variety, in a blend with Vernal increased yield 1.7 mt/ha in the 1st harvest year over Vernal seeded alone. Stride Vernal blend yields were not significantly different (5% level) from Vernal seeded alone in the second harvest year, but significantly less than Vernal in the third and fourth harvest years. Moapa plants died in the first winter after seeding. First harvest‐year yields of MoapaVernal blends were significantly less than Vernal alone. Differences in the second production year were smaller and in the 3rd and 4th harvest years blends containing 33% Moapa seed yielded about the same as Vernal seeded alone (20.35 vs 20.75 mt/ha).

After the Moapa plants died in the first winter after seeding, the remaining Vernal plants gave a stand nearly as productive as Vernal seeded alone. When the Stride plants died after 2 or 3 years the remaining stand of Vernal plants was less productive than Vernal seeded alone. There was little advantage of the blends studied over a single well‐adapted variety.
Effects of Various Nitrogen Sources, Timing, and Rates on Quality and Growth Rate of Cool‐Season Turfgrasses1
Authors: Ledeboer F. B. , Skogley C. R.
Published: July 2010

Fertilizer applications to cool‐season turfgrasses usually consist of treatments in spring, summer, and early fall. Two field studies were designed to compare various fertilizers at different timing and rate schedules on several cool‐season grasses alone and in mixed stands. A 10‐2.6‐3.3 (30% org. N) fertilizer was used at .5, 1.0, and 1.5 kg/ARE in single and split treatments in May, August, September and late November. Ammonium nitrate (AN) and ureaformaldehyde (UF) were compared at equal rates on ‘Merion’ Kentucky bluegrass (Poa pratensis L.). A total of 1.5 kg/ARE was applied in split treatments during the same months as stated above. Turf quality ratings were taken for three seasons, and bi‐weekly clipping weights, for two full growing seasons.

Growth and color responses were correlated with fertilization rates in the first study, but at all three rates, fall and late fall treatments resulted in more uniform turf quality and less clipping weights than with comparable spring and summer fertilization. Calculated CV values were consistently lower for both parameters. Grasses maintained better winter color and greened up earlier in spring. Results with AN in the second study were similar, while UF treatments failed to produce satisfactory turf at the tested rate. Fall and late fall AN applications regularly maintained acceptable turf within acceptable clipping limits.
On the Mechanism of Water‐Stress‐Induced Stem Deformation1
Authors: Molz Fred J. , Klepper Betty
Published: July 2010

Experiments were performed to determine where and to what extent stem deformation occurs in the tissue of water‐stressed cotton (Gossypium hirsutum L.) plants. Such knowledge is necessary if stem contraction is ever to be used as an index of plant water status. Tension in the xylem of cotton stems was released by severing under water, and portions of stem xylem were subjected to positive hydrostatic pressures in a pressure chamber. The results indicate that the mature xylem of a cotton stem is a rigid material that undergoes negligible elastic deformation in the radial direction when subjected to a hydrostatic stress in the vicinity of 10 to 15 bars. Therefore, any measureable deformation in a water‐stressed stem is due almost entirely to dehydration of the living cells found in the phloem and related tissues. These conclusions indicate that it will not be possible to develop a simple relationship between stem diameter changes and plant water status such that a measurement of stem shrinkage can be used to estimate xylem water potential directly. The relationship is complicated by the thickness and water relations of the outer living stem cells.
Estimating Transpiration Resistance1
Authors: Brun Lynn J. , Kanemasu Edward T. , Powers William L.
Published: July 2010

Previous estimates of transpiration resistance have been based on the stomatal resistance of only a few leaves per plant. Because the lower stomatal resistances observed in upper leaves compared to lower leaves in dense canopies could introduce sampling errors, transpiration resistance was determined in a sorghum [Sorghum bicolor (L.) Moench] canopy by two methods based on the stomatal resistance of all the leaves on a plant and a third method based on the stomatal resistance of only the upper three leaves. Stomatal resistance was measured with the diffusion porometer.

The three methods of determining transpiration resistance included: (i) harmonically averaging the stomatal resistance of all the leaves on a plant; (ii) dividing the crop canopy into layers and weighting each layer resistance by its leaf area index; and (iii) harmonically averaging the stomatal resistances of the upper three leaves of the plant. Methods 1 and 2 gave almost identical estimates of transpiration resistance. When methods 1 and 3 were evaluated by the Monteith evapotranspiration model, the evapotranspiration estimate using method 1 gave closer agreement with lysimeter evapotranspiration than when method 3 was used in the model.
Measurement of Leaf Water Potential in Wheat with a Pressure Chamber1
Authors: Frank A. B. , Harris D. G.
Published: July 2010

Estimates of leaf water potential obtained with a pressure chamber and with thermocouple psychrometers were compared for wheat (Triticum aestivum L.) leaves at late tillering and early heading stages of growth. The methods were linearly related for both stages of growth, but the equations were different. The pressure chamber required a separate calibration for estimating water potential of leaves from two locations on wheat plants.
A Tractor‐Mounted Hydraulically‐Operated Soil Sampler for Rapid Soil Coring1
Authors: Schickedanz Dean M. , Onken A. B. , Cummings Ted , Jones Ronald M.
Published: July 2010

A tractor‐mounted hydraulically‐operated soil sampler has been developed that incorporates a number of features required for extensive soil sampling. Speed, adaptability, mobility, accessibility, and safety are advantages of this equipment which are not all sufficiently adequate in currently available models.
A Resistance Model to Predict Evapotranspiration and Its Application to a Sugar Beet Field1
Authors: Brown K. W. , Rosenberg Norman J.
Published: July 2010

A method is needed to extrapolate the detailed micrometeorological and lysimetric determinations of evapo‐transpiration and its dependence on the microclimate and crop factors to fields where such detailed measurements are not made. The dependence of latent heat flux (LE) from a crop on crop resistance (rc), air resistance (ra), air temperature (Ta), water vapor pressure (ea), and net radiation minus soil heat flux (Rn‐S) was evaluated means of an electrical resistance analogue of the transfer process (referred here as the model) and by means an energy balance equation. The difficulties inherent in the application of the model to both the single leaf and the crop are discussed.

The major difficulty in applying the resistance model to a field crop may be that the sinks and sources of latent and sensible heat flux may not be identical within the crop. Hourly LE predicted by the model and determined by the energy balance generally agreed within 5%. Daily totals of LE, evaluated by the two methods, agreed well on all occasions. Despite the objections to use of this model for a crop, it mimicked the behavior of the irrigated sugar beet crop used here. As more detailed data on experimental fields becomes available, the model may prove useful in extrapolation to extensive vegetated areas. It may also be usefully incorporated into larger models of total hydrologic systems in which evapotranspiration is an important component.