bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nutritional Influences on Cold Hardiness of St. Augustinegrass {Stenotaphrum secundatum)1
Authors: Reeves Sim A. , McBee George G. 
Published: July 2010

AbstractThe 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

AbstractContraction 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

AbstractThe 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

AbstractThe 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

AbstractThis 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

AbstractThree 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

AbstractThe 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

AbstractThe 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

AbstractWe 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

AbstractZinc 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

AbstractIn 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

AbstractFertilizer 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

AbstractExperiments 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

AbstractPrevious 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

AbstractEstimates 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

AbstractA 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

AbstractA 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.