bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytogenetic and Taxonomic Relationships among Three Diploid Crested Wheatgrasses1
Authors: Dewey D. R. , Asay K. H. 
Published: July 2010

Until recently, only one diploid (2n= 14) taxon of crested wheatgrass [Agropyron cristatum (L.) Gaertn.] was recognized. This diploid, ‘Fairway’, differs morphologically from two diploid plant introductions, PI 229574 from Iran and PI 314600 from the USSR. The purposes of this study were to: (1) define the genomic relationships among the three diploid taxa, (2) determine if restrictions to gene flow occur among the diploids, and (3) examine the taxonomic implications of the data.The diploid taxa were hybridized with relative ease and produced F1 hybrids that were morphologically intermediate to their parents. Mean chromosome pairing at Metaphase I in the three hybrid combinations ranged from 1.38 to 2.25I, 5.05 to 5.83II, 0.03 to 0.52III, and 0.005 to 0.18IV. The pairing data demonstrate that the diploids contain the same basic genome, but their genomes differ by structural rearrangements of some chromosomes. Stainable pollen averaged 19.3 to 24.6% and seed set averaged 0.25 to 0.58 seeds per spike in the three hybrid combinations. The moderately high sterility in the hybrids serves as a genetic barrier but does not preclude gene flow among the diploids.The three diploid taxa are correctly identified as A. cristatum, but they should be separated at the subspecies level. We think that PI 229574 belongs to A. cristatum subsp. cristatum. However, subspecies designations for Fairway and PI 314600 must be deferred until more information is accumulated.
Gas Exchange and Leaf Area Characteristics of Four Tall Fescue Selections Differing in Forage Yield1
Authors: Cohen C. J. , Chilcote D. O. , Frakes R. V. 
Published: July 2010

Gas exchange and leaf area characteristics of four tall fescue (Festuca arundinacea Schreb.) selections differing in forage yield were examined under greenhouse and laboratory conditions to determine if these characteristics might be related to yield differences. Carbon dioxide exchange rates (CER) and specific leaf weight of leaf blades of ten genotypes per selection were measured in December 1978 and April 1979. In April 1979, dark respiration and transpiration rates of leaf blades were also evaluated. Leaf elongation rate, leaf width, and leaf area expansion rate were assessed during three measurement periods.In December 1978, the lowest‐yielding selection, TFM 16, had 20% greater CER than the high‐yield selections, TFM 26 and TFK 4, and 8% greater CER than TFK 12. Differences in CER were not statistically significant in April. No significant differences among selections for transpiration, dark respiration, or specific leaf weight were found.High yielding TFM 26 had significantly greater leaf elongation and leaf area expansion rates in one measurement period (by 28 to 48% and 24 to 43%, respectively), but differences among selections were not significant in two other periods. Low‐yielding TFM 16 had leaves that were more than 20% narrower than those of the other selections. Leaf width was a relatively more stable morphological character than leaf elongation or leaf area expansion rate.
Inheritance and Anatomy of Root Bark Area in Alfalfa1
Authors: Brick M.A. , Barnes D.K. 
Published: July 2010

The root bark of alfalfa (Medicago sativa L.) has several important physiological functions, including the storage of carbohydrate reserves. The objectives of this research were to determine the inheritance of alfalfa root bark area and compare the anatomical features of plants with a large and small proportion of root bark. Two sets of six clone diallel mating schemes were made to evaluate general combining ability (GCA) and specific combining ability (SCA) effects for root bark area. S2, F1, and F2 families were produced from selected plants to study qualitative inheritance of root bark area. Two plants with contrasting root bark area were studied histologically to investigate their anatomical features.General combining ability effects were highly significant and SCA effects were non‐significant for root bark area in both diallel sets. Qualitative analyses indicated that two tetrasomically inherited non‐dominant duplicate genes (RB1 and RB2) controlled bark area. Root cross‐sections taken 63 cm from the root tip of the two plants used for anatomical studies revealed that 33 and 83% of the sectioned area was root bark. Plants with contrasting root bark area could be distinguished shortly after secondary growth was initiated. Alfalfa populations with contrasting root bark composition are being developed for use in physiological and plant breeding studies.
Effect of Defoliation and Depodding on 14CO2 Assimilation and Photosynthate Distribution in Y‐Shaped Soybean Plants1
Authors: Gent Martin P.N. 
Published: July 2010

To determine the importance of long distance translocation to the yield of soybeans (Glycine max L. Merrill), field‐grown plants were modified by selective pruning to create an imbalance in the number of leaves and the number of pods on opposing branches of a Y‐shaped plant. The Y‐shaped plants were created early in vegetative growth by pinching off the growing apex when the first trifoliolate leaf appeared. After flowering, one group of these Y‐shaped plants was pruned by removing one‐third of the leaflets and one‐third of the pods from both branches (the even treatment), another group was pruned by removing two‐thirds of the leaflets from one branch and two‐thirds of the pods from the opposite branch (the uneven treatment). Plants given the even and uneven treatment were labelled with 14CO2 on three occasions corresponding to days early, middle, and late in pod‐filling. After 24 h, labelled plants were harvested, dried, and the specific radioactivity in each part and the distribution of radioactivity in the various parts of the plant were determined. Some of the labelled plants were allowed to mature before harvest and analysis.The changed leaf area of the treatments remained to the end of the season, but the changed pod distribution did not. Increased abortion of pods and seeds on the deleafed branch and decreased abortion on the depodded branch of the uneven treatment equalized the reproductive load on all the pruned branches during most of the pod‐filling period. The pruning had no effect on photosynthesis per unit leaf area, as measured by assimilation of 14CO2, or on the rate of disappearance of radioactivity from leaves in the first few hours after labelling. Moreover, the movement of the radioactivity out of the leaf or into the seed was unaffected. The uneven treatment did induce a change in the amount of photosynthate retained in the stem of the two different branches; the depodded stem retained twice the radioactivity of the deleafed stem after 24 h. The difference in radioactivity in the stems of different treatments noted 24 h after labelling was also found at the end of the season, though the level of radioactivity was reduced by a factor of 2.The resistance to translocation is sufficient to alter the distribution of concurrent photosynthate to the stem, petiole, and podwall parts but it is not sufficient to change the uptake of photosynthate into the seeds of Y‐shaped plants with an uneven distribution of sources and sinks.
Improved Rotary Sieve for Measuring State and Stability of Dry Soil Structure
Authors: Chepil W. S. 
Published: July 2010

AbstractAn improved rotary sieve designed to overcome the limitations of the original sieve (1) was constructed and thoroughly tested.The improved apparatus is capable of separating dry soil in one operation into any number of dry soil fractions up to 14. The operation requires little technical skill. The results of sieving are independent of personal judgment.The apparatus was found useful for determining the relative mechanical stability as well as the state of aggregation of soil in a dry condition. Mechanical stability, as determined from the relative resistance of soil aggregates to breakdown by repeated sieving, varied directly with the resistance of the soil aggregates to abrasion by wind‐blown soil materials. Abrasion is one of the serious aspects of erosion of soil by wind.The rate of breakdown of soil aggregates varied exponentially with the number of sievings. Assuming this type of relationship to extend beyond the experimental range, the amounts of some particular size of aggregates present in soils before sieving were estimated.
Zonal Soils in the Transition Region between the Podzol and Gray‐Brown Podzolic Regions in Michigan
Authors: Gardner D. R. , Whiteside E. P. 
Published: July 2010

AbstractStudies were made of soil profiles from an area in central Michigan lying along the Podzol‐Gray‐Brown Podzolic transition region. The profiles are grouped in a lithosequence of seven textures from sand to silty clay loam and reproduced photographically. Selected physical and chemical analyses from three of the seven textures are presented tabularly.Through the range of textures studied, these profiles possess a common sequence of horizons. While the surface horizons are clearly those of a Podzol, they are underlain by what appear to be the A2 and B2 of a Gray‐Brown Podzolic profile. The influence of the texture of parent material is such that, in the sandier types, the upper Podzol is much more strongly developed than is the lower Gray‐Brown Podzolic profile while in the heavier textures, the reverse is true.The authors conclude that these double profiles represent the zonal soil for this area and are correlatives of the double profiles described by other workers in New York and in Ontario. These soils are neither true Podzols nor true Gray‐Brown Podzolic soils but exhibit the characteristics of both groups, the affinity for one or the other being related to the texture of the parent materials.
Depth to Plow Pan as a Factor in Sugar Cane Production
Authors: Scarsbrook C. E. , DeMent Jack D. , Sturgis M. B. 
Published: July 2010

AbstractResults from fertilizer studies in the sugar cane growing areas of Louisiana have shown no consistent relationship between native soil fertility as determined by soil tests and yields of sugar cane. In many cases there have been very low responses to the fertilizers. This investigation was made to determine what soil factors were related to yields. Measurements of depth to plow pan, aggregation, organic matter, soluble phosphorus, and exchangeable cations were made on check plots and plots receiving the highest rates of fertilizer.Depth to plow pan was directly related to yield on unfertilized plots. There appeared to be a trend toward greater increases in yield due to added fertilizer as the depth to the plow pan decreased. Except in extreme cases other factors measured had less effect on yields.
Further Studies on the Effect of Long‐time Organic Matter Additions on the Physical Properties of Sassafras Silt Loam
Authors: Russell M. B. , Klute A. , Jacob W. C. 
Published: July 2010

AbstractThe objectives of the investigation were to determine the effects of long‐time differential manure applications on physical properties, organic matter, and nitrogen content; to provide a “bench‐mark” for future studies on the permanence of the observed differences following the discontinuance of the treatments; and to study the distribution of variance among the experimental, sampling, and determination error terms as a guide for planning future studies involving the same plots and measurements.Composited soil samples were taken at three depths from plots representing three replications of each of four treatments. Organic carbon, total nitrogen, moisture equivalent, 15‐atmosphere percentage, aggregate stability, and percent sand were determined on all samples. Proctor compaction and penetrability measurements also were made.Twenty‐five annual applications of manure at rates of 0, 10, 20, and 40 tons per acre have resulted in highly significant differences in organic carbon and nitrogen percentages, aggregate stability, and susceptibility to compaction of Sassafras silt loam. Highly significant positive correlation coefficients were obtained between the organic matter content and the moisture equivalent, 15‐atmosphere percentage, and aggregate stability. Sampling and determination variances were in general well below the corresponding experimental variances.
Colloidal Properties of Soils from Western Equatorial South America
Authors: Miller E. V. , Coleman N. T. 
Published: July 2010

AbstractEquatorial soils of Ecuador and Peru were studied by chemical, differential thermal, and X‐ray spectrographic methods of analysis with the aim of clarifying their classification and fertility properties.A classification key permits the presentation of the soils and their properties according to major soil groups.In the humid tropical regions kaolin clays are common, but there is also evidence of juvenile soils. Immaturity is indicated by high contents of exchangeable bases, presence of clays with high cation exchange capacities, evident lack of crystallinity of the clays, and pH values which are relatively low for the existing degree of base saturation.Dark colored acidic Andean soils possess high phosphate retaining capacities and high exchangeable aluminum. Their C/A capacity ratios are less than 1.Soils of the drier equatorial regions contain crystalline clay minerals of the 2:1 lattice families.
Loss of Phosphorus by Erosion
Authors: Ensminger L. E. 
Published: July 2010

AbstractA study was made of the phosphorus status of soils which had received phosphate applications over a period of years to determine the loss of phosphorus by erosion. Phosphorus that could not be accounted for by analysis of the surface 16 inches of soil and by crop removal was assumed to be loss by erosion.Where corn and cotton was used as the rotation, an average of 63% of the phosphorus applied during a 16‐year period to a Hartsells fine sandy loam soil had been lost by erosion as compared to 40% for a corn, cotton, and winter legume rotation. The results show that most of the accumulated phosphorus could be extracted by a HCl‐NH4F solution. Three plots in the corn, cotton, and winter legume rotation contained 7 to 8% of < 2 µ material in the surface 0 to 8 inches originally, but after 16 years of cropping the < 2 µ material had been reduced to 5 to 6%. The clay fraction contained 25 to 30% of the total phosphorus. These results indicate that only a small part of the phosphorus was lost along with the clay fraction. A study of 22 fields in Baldwin County that had been in potatoes from 5 to 30 years shows that the surface soil accumulated an average of 103 pounds P2O5 per acre per year in potatoes, although an estimated 200 pounds of P2O5 was added each year potatoes were grown. An inventory of the phosphorus status of soils in cement bins after 12 years of phosphate applications shows that 80% or more of the applied phosphorus could be accounted for on the basis of soil analysis and crop removal. The plots were enclosed by cement walls which prevented run‐off except during very heavy rains.
Chemical Determination of Sorbed Water and Structural Hydroxyl in Colloidal Minerals of Soils and Sediments
Authors: Evans E. J. , Jackson M. L. 
Published: July 2010

AbstractA method is described for the differentiation of sorbed water from structural hydroxyl ions for colloidal minerals of soils and sediments. It is based on the extraction of the sorbed water (including external surface sorbed and interlayer water) with methanol. The structural hydoxyl is determined by heating the sample in a silica tube oven, passing a gas through the tube, and collection of the liberated water in methanol. The water contents of the methanol solutions are determined titrimetrically by utilization of the Karl Fischer reagent. This method is preferred to the less satisfactory methods based on thermal weight‐loss. Hydroxyl determinations are given some 2:1 layer silicates and other hydroxyl compounds as examples of the type of studies made possible by the technique.
Status Report on Soil Conditioning Chemicals. II.
Authors: Sherwood L. V. , Engibous J. C. 
Published: July 2010

AbstractTwo synthetic soil conditioning chemicals, hydrolyzed polyacrylonitrile and a modified vinyl acetate maleic acid compound, are described. The effects of conditioner treatment upon the physical, chemical, and biochemical status of the soil, as well as plant composition, yield, and quality are outlined.Observable results of economic importance are discussed, including improved soil workability, reduced soil crusting, effective erosion control, improved crop yields and quality, and earlier planting and maturity.Lines of further research are suggested which may ultimately lead to a better understanding of soil structural relationships and the efficient use of soil conditioner chemicals.Factors influencing specific application recommendations are examined.
A Turbidimetric Potassium Determination Affected Little by Temperature
Authors: Olson R. V. 
Published: July 2010

AbstractA modification of the turbidimetric cobaltinitrite method for determining potassium is presented. The method is applicable to use in routine soil testing laboratories and has been in use for 3 years in Kansas county laboratories.The method is not appreciably affected by temperature changes over the temperature range of 15° to 35° C but is subject to errors at temperatures greater than this. Comparisons of the effect of temperature on this method with two methods now in common use showed it to be subject to less error.The effects of temperature have been minimized by modifying the usual techniques in two ways: (1) by selecting the proper wave length and adjusting the photometer with a blank solution to prevent measurement of the amount of color in the solution phase, and (2) by introducing sodium cobaltinitrite powder directly into the potassium solution‐alcohol mixture, resulting in slow formation of the potassium precipitate.
Field Capacity in Laboratory Columns
Authors: Miller Robert D. , McMurdie John L. 
Published: July 2010

AbstractIt is shown that the material decrease in downward movement observed as soils approach field capacity cannot be explained in terms of capillary conductivity alone. Instead, the combined effects of decreasing capillary conductivity in the drying zone, hysteresis and reduced hydraulic gradients at all levels are involved. The capillary conductivity of the drying zone is always greater (probably much greater) than that of the wetting zone. Hysteresis effects, if present, ought to result in larger reductions in hydraulic gradient for an increment of water transfer than would occur without hysteresis. The hydraulic gradients at all levels ought to decline during drainage.Experimental evidence is presented which is in general agreement with expectations. Hysteresis effects were large, and the hydranlic gradients greatly diminished after 48 hours of drainage.
Water Entry and Downward Movement in Undisturbed Soil Cores
Authors: Taylor Sterling A. , Heuser Neil C. 
Published: July 2010

AbstractWater moves downward in a dry soil from a constant source at the surface according to Darcy's law which, combined with the law of conservation of mass, results in an equation for the downward flow of water in unsaturated soils. This equation has previously been discussed and solved for special conditions. This paper reports progress that has been made in measuring and evaluating the components of this equation for undisturbed soil cores.Six undisturbed cores 10 cm in diameter and 120 cm long and containing different amounts of water were used. Water was allowed to enter the core under a constant head of 1.2 cm. The quantity of water that accumulated in the soil and the depth to the wetting front were measured as functions of time. The soil moisture potential was measured at 5 cm intervals of depth and at various time intervals. From these measurements infiltration rates, moisture potential gradients, and apparent moisture conductivities were calculated. Moisture conductivity was calculated from the moisture retention curve as suggested by Childs and Collis‐George; this technique has not been experimentally verified sufficiently to justify the calculation of the conductivity gradient, hence the flow equation has not been completely solved.The results indicate that the infiltration rate depends primarily on the gradient of the moisture potential and has secondary dependence on the capillary conductivity. Potential gradients in the wetting zone and across the wetting front may be much greater than in the transmission zone and they appear to be a principal factor in determining infiltration rates. Potential gradients were measured and used to calculate apparent capillary conductivity values which are always smaller than infiltration rates. As a result of large potential gradients, the infiltration rates exceeded the saturated permeability in five of the six cores studied.
Factors Affecting Adsorption of Cations by Plant Roots
Authors: Mehlich A. 
Published: July 2010

AbstractThe adsorption of Ca, Mg, K and Na by metabolically inactive H‐roots of wheat and alfalfa in relation to the nature of the anion has been studied. Titration curves and fH values showed wheat roots to have a weaker acid character than alfalfa roots. A high retention of H+ over metal cations was indicated. As a consequence, only small amounts of cations were adsorbed when offered as nitrates, but large amounts were adsorbed when offered as the bicarbonates. The order of increasing adsorption in either case was: Na, K, Mg, Ca.When Ca, Mg and K were offered in exchangeable form on a soil colloid with Ca/Mg and Ca/K ratios of 4, the Ca/Mg ratios on the roots were 4 and 8, and the Ca/K ratios were 10 and 24 for the wheat and alfalfa roots, respectively. The corresponding distribution of cations on the wheat roots were: Ca, 73%; Mg, 19%; K, 8%; and for alfalfa roots they were: Ca, 85%; Mg, 11%; and K, 4%.It is concluded that the adsorption of cations by metabolically inactive roots is a neutralization reaction involving principally Ca. The group of compounds involved in this reaction have been designated as RCOOH. Selective adsorption of cations involving exchange reaction, notably Mg and K, through RH is restricted to metabolically active roots. It is suggested that the proportions of K to Ca entering the plant is related to the concentration and proportion of RH to RCOOH of roots.
Potassium Competition in Grass‐Legume Associations as a Function of Root Cation Exchange Capacity
Authors: Gray Bryce , Drake Mack , Colby Wm. G. 
Published: July 2010

AbstractLadino clover, smooth brome grass. Kentucky bluegrass and bentgrass were grown in greenhouse pots to determine the relative uptake of K by the species when grown separately, and to study the competition for K when Ladino clover was grown in association with each of the three grasses. This was to determine to what extent the theory of differential cation uptake by plants of different root cation exchange capacity can explain the disappearance of legumes from pasture mixtures as a result of plant competition for K. Potassium uptake by plant species at low levels of soil K was closely correlated with root cation exchange capacity. The relative K compatibility was smooth brome (best). Kentucky blue (intermediate) and bentgrass (poorest). Because of the strong attraction and high uptake of K by roots of bentgrass, it was impossible with practical rates of K fertilization to maintain an adequate K supply for the associated Ladino clover.