bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Sampling Frequency on the Precision of Estimating Accumulated Solar Radiation1
Authors: Holt D. A. , Youngberg H. W.
Published: July 2010

Instantaueous solar radiation intensity measurements were recorded at various time intervals. These were numerically integrated over individual days and the accumulation estimates thus obtained were compared to daily totals read from an integrating device operating continuously on the same Eppley pyranometer. Precision of daily accumulated radiation estimates decreased as time interval between intensity measurements increased. In the entire sample of 100 days, the standard deviations of differences between integrator values and calculated estimates increased about 0.5 Langley per additional minute in interval between measurments. Precision loss with increase in time interval was greater on variable days than on consistent days and about the same on bright and dull days. Precision was greater and decreased less with time interval on dull, consistent days than on dull, variable days and on bright, consistent rather than bright, variable days.
Effects of Bottom Defoliation on Microclimate and the Reduction of Boll Rot of Cotton1
Authors: Ranney C. D. , Hursh J. S. , Newton O. H.
Published: July 2010

In 1963 and 1964, increases in boll rot of cotton were associated with short periods (5 to 7 days) of rainfall and, to a lesser extent the drying period following rainfall. Microclimate changes within the plant canopy associated with these periods indicate that increased duration of relative humidity at a level of 95% or higher, increased duration of free moisture, and reduced intensity of light, all favor boll rot development. Bottom defoliation reduced boll rot loss and modified the microclimate resulting in shorter duration of 95% or higher relative humidity; it increased light intensity in the lower plant zone, and possibly increased ventilation following periods of rainfall. Instrumentation used for microclimate measurements are described; and construction details of a simple mechanical psychrometer and a light intensity sensor‐recorder are presented.
Soil Temperature and Residue Effects on Growth Components and Nutrient Uptake of Four Wheat Varieties1
Authors: Whitfield C. J. , Smika D. E.
Published: July 2010

Wheat (Triticum aestivum L.) spring varieties ‘Lee’ and ‘Crim’ and winter varieties ‘Wichita’ and ‘Lancer’ were grown in the greenhouse to study the effects of three soil temperatures, 7, 13, and 18C, with and without straw mulch, on yield components and plant nutrient uptake. The presence of straw mulch depressed most growth components of the spring wheat varieties Lee and Crim but differences were seldom significant. With the winter wheats number of tillers of Wichita, number of heads of Lancer and root weights of both varieties were lower, but not significantly so, with surface residue. Growth of all varieties tended to be poorest at 7C with the effect of straw mulch most pronounced at that temperature. Most growth components of each variety grew best at 18C where the depressive effect of straw mulch was frequently overcome; however, winter wheats had more heads and head weights were highest at 13C. Uptake of essential elements by plant parts was significantly influenced by temperature, but residue had no effect on plant uptake in tops and only limited effect on uptake in crowns and roots.
Seedbed Preparation, Intertillage Operations and Chemical Weed Control for Sugarcane Growth and Quality
Authors: Agrawal J. P. , Jain N. K.
Published: July 2010

Objectives were to determine the optimum number of cultivations in preparing the seedbed of sugarcane (Saccharum interspecific hybrid, cultivar ‘CoS 510’) and to find out whether any deficiency in initial cultivation can be made up by more intensive post‐planting tillage or other weed control measures.

Two cultivations with a “country” plow after a soil inversion plow were sufficient for seedbed preparation of sugarcane under optimum moisture conditions in a sandy loam alluvium soil of the Indogangetic plains. More cultivations increased proximate growth, but the effect slowly waned and was not reflected in the final economic characters at harvest. Effect of post‐planting treatments on growth, yield, and juice quality of sugarcane was proportionate to their effectiveness in weed control. Deep hand hoeing was the most effective post‐planting operation, closely followed by simazine spray and sugarcane trash mulch. The latter conserved soil moisture and could economize on irrigation during the premonsoon period. Spraying with 2, 4‐D and scraping off weeds between rows of sugarcane with a bladed wheel hoe had very little effect. There was no interaction between number of cultivations in seedbed preparation and post‐planting treatments.
Response of Corn to Small Amounts of Fertilizer Placed with the Seed: IV. Comparison of Dry and Liquid Forms1
Authors: Baweja A. S. , Bates T. E.
Published: July 2010

Powdered and granular fertilizers containing 13.3, 23.1, and 11.0% N, P, and K, respectively, were prepared along with water solutions of the same material containing 10.5 and 4.4% P. These fertilizers were banded with the seed of corn (Zea mays L.) in greenhouse trials in which respiration rate, axis length, emergence, dry matter yield, and N, P, and K content were measured. No differences in nutrient availability were found between liquid and dry fertilizers studied. Granular and powdered materials were equal in toxicity. They were more toxic to corn seedlings, as measured by axis length, emergence, or dry matter yields, than the less concentrated liquid materials applied at rates providing the same total quantities of plant nutrients. Use of dilute (low‐analysis) fertilizers is probably not a practical way of reducing toxicity because of the amount of dilution required.
Control of Volunteer Oat in Alfalfa1
Authors: Kust C. A.
Published: July 2010

Simazine, atrazine and terbacil were applied to alfalfa (Medicago sativa L.) stands, established with oat (Avena sativa L.) as a companion crop, after the oat was harvested at maturity. Herbicides were applied before the germination of volunteer oat or after both oat and alfalfa had made substantial growth. Excellent control of volunteer oat, without significant alfalfa injury, was obtained with all three herbicides. Control generally was better if the herbicides were applied in September rather than in August. Root carbohydrate reserves of alfalfa may have provided some physiological protection against herbicide injury.
Nonuniform Distribution of Fertilizer and Its Effect on Corn Yields1
Authors: Langdale G. W. , Myhre D. L. , Miller R. J.
Published: July 2010

Nonuniform distribution of a homogeneous mixed fertilizer was evaluated at six nonuniform levels with a modified split plot design on a Plinthic Paleudult soil during 1961 and 1962. Observed and calculated yield losses resulting from ≤ 50% nonuniform band fertilization are presented.

Fertilizer variations greater than 40% were required to obtain significant (P ≤ .05) experimental yield losses. Standard partial regression coefficients and plant tissue nutrient contents suggest that nonuniform distribution of N provided a primary influence on yield loss rather than P or K. Concomitant losses of N in leaf tissue and grain yields due to nonuniform distribution were related. Crop yield losses resulting from expected fertilizer variation becomes more serious when related to uniform‐profit maximizing conditions.
Nitrate‐nitrogen Accumulation under Bromegrass Sod Fertilized Annually at Six Levels of Nitrogen for Fifteen Years1
Authors: Larson K. L. , Carter J. F. , Vasey E. H.
Published: July 2010

An old bromegrass sod established prior to 1929 and fertilized annually since 1954 with nitrogen at rates from 0 to 298 kg/ha responded with increased forage, protein, and seed yields. Nitrate‐N content of the soil profile after 15 years of fertilization was analyzed using an Orion 401 specific ion meter with a NO3‐N electrode to determine the possible pollution of ground water with nitrates attributable to increased nitrogen fertilization. Nitrate‐N content was similar below 106.7 cm to a selected depth of 137 cm during late April and of 152 cm during late June and August in 1969 under each of six fertility treatments. Highest concentration of NO3‐N was found in the soil profile from 15.2 to 61.0 cm in depth. Results suggest apparent lack of NO3‐N movement and accumulation in fine‐textured soils under northern climatic conditions even under high rates of continuous nitrogen fertilization.
Effect of Gypsum and Drought Stress on Maize (Zea mays L.). I. Growth, Light Absorption and Yield1
Authors: Downey Lloyd A
Published: July 2010

An experiment was designed to study the effect of gypsum and drought stress on growth, water status and yield with maize (Zea mays L.). Water status was assessed under field conditions by measurements of relative turgidity (RT) at noon. No stress was defined as RT greater than 90% — drought stress as RT less than 90%. A nostress crop was compared with a crop drought stressed for a period of 20 days during male meiosis and with a crop drought stressed during grain filling (after pollination to maturity). These treatments were set out in a randomised block design with a further comparison between the untreated sodic clay soil (control) and the same soil treated with gypsum.

Gypsum and no‐stress conditions stimulated tiller production so that the final effective plant densities were above optimum. The no‐stress treatments produced large amounts of dry matter but this was channelled into sterile tillers rather than into grain. Drought stress during male meiosis stunted growth, stunted tassel development, reduced chlorophyll content and light absorption (during the period of stress) but, overall, was not very detrimental to grain yield. Drought stress during grain filling reduced grain yield by 50%; grain weight was reduced and a very high proportion of photosynthate went into sterile tillers.
Effect of Sulfur Fertilization of Forage Species on Yield, Chemical Composition, and In vitro Rumen Microbial Activity of Sheep1
Authors: Lancaster D. L. , Jones M. B. , Oh J. H. , Ruckman J. E.
Published: July 2010

Three grasses, (Dactylis glomerata L.), (Lolium multiflorum L.), and (Sorghum vulgare var. sudanese L.), and two legumes, (Trifolium repens L.) and (Medicago sativa L.), were grown in pots on S‐deficient soil fertilized with varying levels of S. In vitro rumen microbial activity as affected by these forages was measured in terms of total gas production using an anaerobic manometric technique. The rumen microbial activity in the grasses increased with increasing S, whereas it decreased with increasing S in the legumes. The microbial activity was inversely related to the level of protein in the plants and directly related to soluble carbohydrates.
Effect of Seedbed Configuration and Cotton Bur Mulch on Lint Cotton Yield, Soil Water, and Water Use1
Authors: Koshi Paul T. , Fryrear Donald W.
Published: July 2010

Better management techniques and planting schemes are needed for the dryland agriculture of the Southern High Plains of the U.S. To test various possibilities cotton (Gossypium hirsutum L.) was grown on three seedbed configurations (flat, ridge, and furrow) with four mulch rates (0.0, 5.6, 11.2, and 22.4 tons/ha of cotton bur mulch). Soil water was measured to a depth of 300 cm by the neutron method.

Preseason soil water storage (mid‐January to mid‐June) was highest for the 22.4 tons/ha mulch and least for no mulch. Precipitation storage efficiencies were 46, 68, and 80% from 34.0 cm of precipitation in 1968 and 36, 47, and 66% from 33.4 cm of precipitation in 1969 for the 0.0, 11.2, and 22.4 tons/ha mulch rates, respectively.

The furrow plots had the highest accretion, and ridge plots, the least in 1968. During the 1969 season, accretion was highest in the furrow and similar in the flat and ridge plots.

The 1968 soil water accretion and depletion showed the same relationship and similar quantities for the three mulch rates and seedbed configurations. Because of excessive precipitation at the end of the 1969 growing season, less depletion than accretion occurred from the two higher mulch rates.

In 1967 cotton yields were similar in the 0.0 and 5.6 mulch subplots but were less than on the 11.2 and 22.4 tons/ha mulch subplots. In 1968 and 1969 yields were similar for the 11.2 and 22.4 subplots, but were significantly more than either the 0.0 or 5.6 tons/ha mulch subplots. More cotton was produced as a result of 5.6 tons/ha mulch than no mulch in 1968 and 1969 after two and three successive annual applications of mulch.
Simultaneous Measurements of Solution Absorption, Transpiration, Relative Plant Water Content and Growth1
Authors: Harris Donald G.
Published: July 2010

Instrumentation is described for the frequent and simultaneous measurement of solution absorption and relative green weight of large individual plants from which transpiration, relative plant water content, and plant growth are calculated. The method is sensitive, nondestructive, and most useful when used in connection with an automatic digital data acquisition system. The system is ideal for monitoring the dynamics of the water status of a large living plant. Measurements made on cotton plants are presented.

Relative plant water content (RPWC), defined as the ratio of relative plant green weight at time of interest to that just prior to lights‐on, corrected for accumulated CO2 assimilation, was found to be a good measure of plant water status. Resolution of RPWC is at least 10 times better than leaf density measurements made with beta‐gauging techniques. The measurement is instantaneous and can be repeated as often as desired.
Influence of Relative Humidity and Associated Anion on the Absorption of Mn and Zn by Soybean Leaves1
Authors: Rossi N. , Beauchamp E. G.
Published: July 2010

The influence of the relative humidity (RH) and either CI‐ or SO4= as the accompanying anion on Mn and Zn uptake by soybean (Glycine max L. cv ‘Altona’) leaf blades were studied in a growth chamber experiment over a 7‐day period. The quantities of Mn and Zn washed off with water, adsorbed, absorbed, and translocated (by difference) were determined 0.5, 3, and 7 hours and 1, 3, 5, and 7 days after application.

The portion of the applied Mn or Zn absorbed by the leaf blades was small. However, the adsorbed quantities of both cations differed with the associated anion, relative humidity, and time of sampling.

The rate of absorption of either Mn or Zn was most rapid during the first 24 hours of the 7‐day period. The quantities of Mn and Zn in the leaf blades were larger at 70% RH than at 25% RH. Absorption of both Mn and Zn was greater with the chloride rather than the sulfate salt. The apparent translocation of Zn out of the leaf blades was greater with the sulfate rather than the chloride salt. The apparent translocation of Mn out of the leaf blades was greater with the chloride salt. However, a smaller portion of the absorbed Mn or Zn was translocated out of the leaf with the chloride rather than the sulfate salt. It appeared that salt hygroscopicity had little influence on either Mn or Zn adsorption since there was no interaction between relative humidity and the accompanying anion.
A Visual Irrigation Guide for Maize (Zea mays L.)
Authors: Downey Lloyd A.
Published: July 2010

A guide for timing irrigation of maize to minimise water stress was developed. The guide utilized visual estimates of leaf relative water content (RWC) — taking a value of 90% as a critical lower limit. Known relationships between soil matric potential and vapour pressure deficit were used to define the critical RWC in a variable environment. In a semi‐arid situation a simple measurement of temperature could replace the more complicated measurement of vapour pressure deficit. Hence need for irrigation could be ascertained from a graph, using a visual estimate of RWC and a measurement of air temperature. Elsewhere, vapour pressure deficit would have to be used instead of air temperature.
Influence of a Root Crop on Physical Properties of a Medium‐Textured Soil1
Authors: Gerard C. J. , Mehta H. C.
Published: July 2010

Studies to evaluate the influences of stage of growth of a root crop and two plant densities on certain physical properties of a medium‐textured soil were conducted. Dynamic changes with time, depth, and plant population occurred on selected physical properties of medium‐textured soils being cropped to fall radishes. After 2 months, radish roots compacted and decreased the permeability of the top 15 cm of soil but had little influence at the 15‐ to 30‐cm depth. However, after 4 months the enlarged radish roots decreased the compactness and increased the permeability of the top 15 cm of soil but compacted the soil at the 15‐ to 30‐cm depth. Field measurements of soil strength described the zone of compaction by radish roots. Compaction by double row radishes was significantly greater than by single‐row radishes.
Influence of Harvesting Method on Rotenoid Yields from Tepbrosia vogelii Hook F.1
Authors: Gaskins M. H. , Stone E. G.
Published: July 2010

The leaves of Tephrosia vogelii, a potential commercial source of rotenoids for insecticides and piscicides, were harvested by two methods: by stripping all leaflets from mature plants at one time, and by clipping the entire plant tops two or more times. The repeated clipping procedure gave higher rotenoid yields. New top growth developed when the plants were first clipped at 45, 60 or 75 cm above ground level. After the second harvest, growth was slow and erratic. The clipping heights of 60 and 75 cm gave best yields with three of four breeding lines tested.

The harvested material contained 20 to 30% stems when the clipping procedure was used. These were not woody, and were judged suitable for extraction by any process adapted to leaves alone.
Comparison of Fall, Winter, or Spring N‐P‐K Fertilizer Applications for Corn and Cotton1
Authors: Boswell Fred C.
Published: July 2010

Field studies compared yields between plow‐down and sidedress N and fall, winter, and spring applied P‐K for corn (Zea mays L.) on Piedmont soil and corn and cotton (Gossypium hirsutum L.) on Coastal Plains acid soils. There were no significant yield differences for the Piedmont soil. For the Coastal Plain soil over a 3‐year period, winter‐ and spring‐applied P and K were superior to fall applications and sidedress N was better than plow‐down N for corn production. Similar N responses were obtained for cotton. However, there was no difference between the fall‐ and winter‐applied P and K, but the spring application yielded significantly (P—.01) more lint cotton than the fall or winter treatments.
Productivity and Quality Response of Five Spring Wheat Genotypes, Triticum aestivum L., to Nitrogen Fertilizer1
Authors: McNeal F. H. , Berg M. A. , Brown P. L. , McGuire C. F.
Published: July 2010

Five spring wheat (Triticum aestivum L.) varieties were fertilized with five N treatments in 1969 and two N treatments in 1970 near Belgrade, Mont. The varieties were chosen to represent short, medium, and tall height levels, and each was evaluated for agronomic and quality response.

Grain yields of normal ‘Centana’ and medium Centana were similar, even though medium Centana was 25% shorter and the straw yield was 17% less. There was no variety‐by‐fertilizer interaction for yield, indicating that the short and medium height types did not respond any better to N fertilizer than the standard height types. Short Centana had significantly less of its protein translocated from plant to grain than tall or medium Centana. Gain protein percentages decreased as the grainstraw ratio increased, suggesting that the amount of top growth is important in extracting nutrients from the soil.

Nitrogen fertilizer significantly increased grain protein percentages, and there was a corresponding increase in loaf volume and grain and texture scores. Baking absorption and mixing time decreased slightly with increasing amounts of N.

Water use was similar for the five varieties and increased with increasing rates of N.
Selection of Soils for Pastures Using Common Chemical Measures1
Authors: Beeson Kenneth C. , Goytendia Alejandro , Gomez Guillermo G.
Published: July 2010

Nutritional data on pasture quality have been correlated with chemical data on related soils to provide criteria for selecting forested or other nonagricultural sites potentially capable of producing pasture of adequate quality for grazing animals in eastern Peru.

With the selection of crude protein as being of first importance, a minimum level of 3% organic matter in a soil identified two‐thirds of the soils investigated that produced pastures containing a concentration of 8% or more crude protein in the moisture‐fee forage. Application of the additional criterion for adequate P in the forage, 0.02% of soil N, identified 80% of the soils producing adequate protein.

Regression coefficients for concentrations of plant constituents — P, Co, Cu, Mn, Ca — and crude protein on soil measures, pH, total N, organic matter, exchange capacity, and exchangeable Ca are presented.
Cultivar Differences among Calcium‐deficient Kentucky Bluegrass Seedlings1
Authors: Nittler L. W. , Kenny T. J.
Published: July 2010

Since many improved Kentucky bluegrass (Poa pratensis L.) cultivars are available for turf purposes, it is important to develop methods of distinguishing among cultivars to insure correctness of labeling of seed in this respect. To detect differences in the seedling stage plants were grown in sand and were supplied either with a complete nutrient solution or with solutions lacking various essential elements. Cultivars differed greatly when plants were grown without calcium. Of 23 cultivars tested, most seedlings of five cultivars were green and healthy after 4 weeks without Ca. Most plants of nine cultivars were very chlorotic, and plants of the other nine were intermediate or were mixtures of healthy and chlorotic plants. Leaf blade tips of many Ca‐deficient plants became red, and cultivars differed in percentage of plants showing this characteristic.

Previous research has shown cultivars to differ in development of anthocyanin in lower leaf sheaths. This pigment was increased by moderate Ca deficiency. Our results indicate that growing seedlings without Ca is a useful technique in cultivar identification.
A Preliminary Investigation of Water‐Soluble Inhibitors in Atriplex Polycarpa Using the Fungus Trichoderma Viride1
Authors: Askham Leonard R. , Cornelius Donald R.
Published: July 2010

The leafy material from Atriplex polycarpa contains 1.15% saponin. Comparative inhibition of Trichoderma viride mycelium indicated that saponin from A. polycarpa was either much more potent than commercially available saponin from the bark of Quillaja, or that other water‐soluble inhibitors were also present. Distilled water, dripping through A. polycarpa plants to simulate rain, also removed inhibitory substances from A. polycarpa.
Recording Water Use by Means of Digital Equipment1
Authors: Payne Leland F. , Schreiber H. A.
Published: July 2010

A device made of digital components is described that automatically (i) senses a discrete loss of water in individual hydroponic cultures; (ii) stores this information as identifying numbers in an 8 2‐digit word memory; and (iii) displays this information on an electric typewriter at 1‐minute intervals.

As many as 16 readings a day can be obtained in a greenhouse, if the ratio of leaf area to water surface area is high enough. This equipment, then, gives a sensitive measurement of water use related to climatic, genetic, or physiologic treatments.
Influence of Mulch on Postharvest Soil Temperatures and Subsequent Regrowth of Alfalfa (Medicago sativa L.)1
Authors: Evenson P. D. , Rumbaugh M. D.
Published: July 2010

A study was initiated to evaluate the influence of postharvest soil temperatures on alfalfa (Medicago sativa L.) regrowth. Wheat (Triticum aestivum L.) straw was applied to alfalfa in a variety trial following the second 1968 harvest to reduce soil temperature. Yield increases of mulched plots over unmulched plots were smallest on first harvests (<7%) and largest (43% in 1969 and 1970) on third harvests. Annual yield increases were 11% in 1969 and 17% in 1970. Straw mulch increased plant height, delayed maturity, and increased soil moisture, but did not affect alfalfa stands. Soil temperatures were as much as 9 C lower in mulched as compared to unmulched plots. Largest yield increases from mulching occurred when temperature differentials between the control and mulched plots were the greatest. Apparently, high soil temperatures are a major factor in controlling alfalfa yields.
Herbicides vs Oat Companion Crops for Alfalfa Establishment1
Authors: Schmid A. R. , Behrens R.
Published: July 2010

Herbicides are effective for use in establishing alfalfa (Medicago sativa L.) without the use of a companion crop. The objective of the study was to assess the economic feasibility of the herbicide method as compared to the companion crop method and to determine some of its advantages and disadvantages.

Productivity of ‘Vernal’ alfalfa established with or without a companion crop was determined at four locations in Minnesota. Oats (Avena sativa L.), harvested for either hay or grain, was used as the companion crop. Four herbicide treatments (EPTC, EPTC + 2,4‐DB, trifluralin, and benefin) were used for weed control when the alfalfa was grown alone. The EPTC soil incorporated treatment plus a postemergence treatment of 2,4‐DB on the alfalfa at the 3 to 4 trifoliolate‐leaf stage was the most effective treatment for controlling weeds.

With prices of $27.56/MT for alfalfa hay, $4.20/100 kg for oat grain, and $16.54/MT for oat straw, the net return (excluding costs common to all methods) favored alfalfa establishment with oats harvested for grain and straw.

During the establishment year the oat hay companion crop yielded 5.17 metric tons (12% moisture)/ha, while alfalfa grown alone yielded 4.03 metric tons/ha. Oat grains averaged 2,205 kg/ha, and straw yields averaged 5.46 metric tons/ha. Stand counts of alfalfa in the fall of the seeding )year were generally higher for alfalfa grown without a companion crop, but this did not affect the following year's yield.

With prices of $27.56/MT for alfalfa hay, $4.20/100 kg for oat grain, and $16.54/MT for oat straw, the net return (excluding costs common to all methods) favored alfalfa establishment with oats harvested for grain and straw.
Nitrate‐N Levels of Perennial Grasses as Affected by Time and Level of Nitrogen Application1
Authors: Ryan M. , Wedin W. F. , Bryan W. B.
Published: July 2010

Increased interest in perennial forage grasses has been further augmented by their versatility in use and by moderating prices of commercial N. Relatively little information is available, however, on nitrate levels in the grasses managed and fertilized to maximizef forage production in the fall. In this study, timing and levels of N applications to orchardgrass(Dactylis glomerata L.), smooth brome (Bromus inermis Leyss.), tall fescue (Festuca arundinacea L.), and reed canarygrass (Phalaris arundinacea L.) were varied. Split or bulk applications of N, ranging from 0 to 540 kg/ha, were made in April, June, and late July. Nitrate ‐N (NO3‐N) percentages greater than 0.15% were considered as potentially “unsafe.” Such percentages were observed in some instances after applications of 135 kg/ha of N in April or June and 540 kg/ha in late July. Results of analyses showed that orchardgrass and tall rescue were significantly higher in percent NO3‐N than either smooth brome or reed canarygrass. Tall fescue tended to be high in percent NO3‐N the fall. Thus, as with sudangrass (Sorghum vulgare sudanense) and orchardgrass, tall rescue may be a forage potentially unsafe under certain conditions of N fertilization.
Yield and N Accumulation of Meadow Forage Fertilized at Advancing Maturity with N1
Authors: Rumburg C. B.
Published: July 2010

These experiments were conducted to compare the efficiency of utilization of N applied early in the spring with that applied at increasingly later stages of herbage maturation and to determine if the N concentration of mature herbage could be increased by delayed applications of N fertilizer. Herbage growth and N accumulation were measured at regular intervals from meadows unfertilized and fertilized with N at increasingly later stages of herbage maturation. Nitrogen increased herbage production, but yields declined as the date of application was delayed. Yields from plots fertilized in June or July were lower by about 10 and 23%, respectively, than yields from plots fertilized in mid‐May. Nitrogen was rapidly accumulated in herbage soon after application, but the maximum accumulated concentrations decreased from more than 3 to less than 2% as the date of fertilization was delayed from May until July.
Oxidant Injury to Shade Tobacco Cultivars Developed in Connecticut for Weather Fleck Resistance1
Authors: Menser H. A. , Hodges G. H.
Published: July 2010

Thirteen tobacco (Nicotiana tabacum) cultivars developed by the cigar industry for resistance to weather fleck in Connecticut were tested at Beltsville, Md. for their responses to air pollutants. We sought information concerning the degree of fleck resistance among the new cultivars under conditions of high oxidant stress. Most of the improved cultivars showed significantly more resistance to ozone than ‘AST‐C’ (Bel‐C), a cultivar no longer grown because of its susceptibility to weather fleck. Two‐hour fumigations at 10 pphm ozone inflicted less than 10% injury on commercial cultivars. The same dosage injured about 20% of the leaf surfaces of Bel‐C. The increase in leaf injury to the commercial cultivars was more pronounced between ozone rates of 15 and 20 pphm, compared to 10 and 15 pphm. Ozone used at 20 and 25 pphm produced about 25% injury on the two most resistant selections, ‘GC 18’ and ‘CCC‐L.’ The same rates destroyed 60 to 70% of the leaves of Bel‐C. Weather fleck evaluations in the field disclosed that photochemical oxidants injured less than 3% of the leaf area of three commercial cultivars, but damaged 55% of the leaf surfaces of Bel‐C. The most leaf injury to an improved cultivar was 25%. Improved cultivars displayed less than 20% fleck damage in the first and second harvest primings, compared to 75% damage in the same two primings of Bel‐C. Results clearly demonstrate the success achieved in controlling weather fleck by using plant breeding methods.
Germination and Establishment of Salsola in Relation to Seedbed Environment. I. Temperature, Afterripening, and Moisture Relations of Salsola Seeds as Determined by Laboratory Studies1
Authors: Young James A. , Evans Raymond A.
Published: July 2010

Our purposes were to investigate the germination characteristics of Russian thistle (Salsola kali var. tenuifolia Tausch.) and to identify the characteristics that control the periodicity of germination for this species. Germination tests were conducted at constant and alternating temperatures from —9 to 30 C and at various moisture potentials. Seeds for testing were collected at intervals from maturity until the following spring. Seeds of Russian thistle have temperature‐dependent afterripening requirements that depress germination at high and low temperatures soon after maturity. There are several distinct steps in the phenological development of the germination of Russian thistle seeds. The rate of development is extremely rapid at high temperatures. When afterripening requirements are satisfied in March and April germination will occur with subzero C nighttune temperatures and 2 C daytime temperatures. Germination was very low on the surface of a media held at —0.1 bars matric potential if the atmosphere around the seeds has a moderate to high moisture stress. Afterripening requirements are the major, but not the only factor, governing the periodicity of germination of Russian thistle seeds.
Some Factors Affecting Asymbiotic Nitrogen Fixation in Soils as Measured by 15N Enrichment1
Authors: Fehr P. I. , Pang P. C. , Hedlin R. A. , Cho C. M.
Published: July 2010

The use of the isotopic 15N technique to measure asymbiotic N fixation in soils has been reported by very few workers, despite the obvious advantages of the technique in assessing the importance of this fixation in agricultural soils.

The effect of glucose plus cellulose (0 and 0.5% glucose + 0.5% cellulose), glucose alone (0, 0.04, 0.2, 1.0 and 5.0% on dry soil weight basis), incubation temperature, method of soil aeration, and atmospheric composition on N fixation in soil in a closed system using 15N was investigated.

Significant fixation was observed mainly when a readily available supply of energy such as glucose plus cellulose or glucose alone was added to the soil. Aerating the energy‐enriched soil by diffusion resulted in greater N fixation under an aerobic and anaerobic atmosphere than aerating by a continuous air flow in a closed system.

The optimum glucose concentration was 1% at the 15 and 35 C incubation temperatures employed, while 5% glucose resulted in greater fixation at the 25 C temperature. Generally, more N was fixed at 15 and 25 C than at the 35 C incubation temperature.
54Mn Incorporation into Plants and Subsequent Metabolism by Rats1
Authors: Lassiter J. W. , Coston M. L. , Miller W. J. , Morris H. D.
Published: July 2010

Little information was available on metabolism by animals of Mn in chemical forms existing in plants. Incorporation of 54Mn into plants is a practical way to facilitate such studies; however, before this could be done, studies were required on factors affecting 54Mn uptake by plants. Accordingly, the influence of dose levels and dose‐date and harvest‐date on 54Mn uptake by four plant species were studied. Also, the absorption by rats of the 54Mn incorporated into plants was studied.

Increasing 54Mn dose level from 0.86 to 8.6 and 86 µCi decreased uptake. Applying the dose 19 days after planting increased 54Mn uptake, as compared to applying it 12 days after. Uptake by soybeans [Glycine max (L.) Merrill] was higher than by corn (Zea mays L.), millet (Panicum sp.), or sorghum [Sorghum bicolor (L.) Moench] ✕ sudan (Sorghum vulgare sudanense), especially at the lowest dose level.

Livers of weanling male rats fed 54Mn forage contained only one‐third as much 54Mn as those of rats given 54MnCl2. Similar effects were evident in kidneys and duodenum. Thus, Mn in forage was much less available to rats than Mn as the chloride illustrating the importance of chemical form of Mn on its metabolism and value to animals.
Concentrations of N and P in Young Corn Plants, as Affected by Various Growth‐limiting Factors1
Authors: Terman G. L. , Noggle J C , Engelstad O. P.
Published: July 2010

Yields and concentrations of N and P were studied in young corn (Zea mays L.) plants as a basis for correct interpretation of plant analysis results. The corn was grown on soils deficient in these nutrients in several greenhouse pot experiments comparing rate, source, and placement of N or P. Results from such pot experiments were satisfactory for establishing minimum and critical nutrient concentrations in corn if various growth‐limiting factors were properly corrected. These included age of plant, application rates of one or more deficient nutrients, and adequacy of other yield‐limiting factors, including liming and other nutrients.

The minimum concentrations of total N or of P in corn forage appear to be rather constant for a given age of plant and can be more accurately estimated than critical concentrations can. The results suggest the estimation of critical values from the minimum concentrations.

C‐type curves resulting from plots of dry matter yield vs nutrient concentration could be explained largely by dilution resulting from growth response to application of a second deficient nutrient.
Effect of Irrigation, Harvest Interval, and Nitrogen on the Yield and Nutrient Composition of Napiergrass (Pennisetum purpureum)1
Authors: Capiel Modesto , Ashcroft Gaylen L.
Published: July 2010

Studies were conducted in a subhumid area of Puerto Rico to investigate the main effect and the interrelations of harvest interval, irrigation, and N fertilization on the yield and nutrient composition of napiergrass (Penniseturn purpureum). Harvest interval exerted the main effect on the dry matter yield of the forage. Nitrogen fertilization and irrigation also had highly significant effects. Irrigation interacted significantly with harvest interval to influence forage yield. The increase in yield as a result of a longer harvest interval was nearly 92% greater on irrigated than on nonirrigated plots.

Nitrogen fertilization produced a highly significant increase in the protein yield of the forage. No other management treatment appreciably influenced protein yields. Significant negative correlations were obtained between yield and both N and K composition for the forage on the frequently harvested, irrigated plots. Both nutrients were at lower concentration in the forage produced in harvest periods that had high yields.
Effects of Length of Cut and Leaf Surface Treatments on Digestibility of Fresh Forage1
Authors: Monson Warren G. , Burton Glenn W.
Published: July 2010

Digestibility of leaves of pearl millet, napiergrass, and bermudragrass was increased by several treatments. After 48 hours in rumen fluid, average dry matter losses from leaves cut to lengths of 2.5, 1.2, .6, and .3 cm were 17.1, 25.9, 30.6, and 42.8%, respectively. When leaves were pressed on a rough surface or abraded with sand paper to break the cuticle, average dry matter losses were from 2.5 to 5 times (mean = 3.2) the losses from intact leaf sections. Increasing the cut surfaces or rupturing the cuticle enhanced the digestion of fresh forage by rumen micro‐organisms.
Growth and Composition Responses of Soybeans to Some Growth Regulators1
Authors: Basnet B. S. , Paulsen G. M. , Nickell C. D.
Published: July 2010

Some growth regulators studied for morphological and yield effects on soybeans [Glycine max (L.) Merr.] have not been studied for chemical compositional effects, particularly under Great Plains conditions. The objective of this study was to compare morphological aud mature seed compositional responses of 11 growth regulators.

Eleven growth regulators of various modes of action were applied at two rates to foliage of soybeaus at one‐tenth bloom stage to study their effects on plant growth and seed composition. The desired rate of each growth regulator was applied in 1 liter of water containing 0.02% (v/v) polyoxyethylene sorbitol monolaurate as a surfactant per plot.

Morphological characteristics responded more than did the chemical constituents, oil and protein, to the growth regulators. Responses were changes in the node number subtending the first pod, number of branches, and number of pods per plant. The antiauxin triiodobenzoic acid reduced plant height, node number, and node number subtending first pod; and increased branching and pod set. None of the growth regulators, however, increased yield when compared to no treatment. Although none of the regulators appeared useful by itself for commercial soybean production, some might have a role under stress conditions or combined with other regulators.
Nitrogen Nutrition and Yield Relations of Nugaines Winter Wheat1
Authors: Laopirojana Pojanee , Roberts S. , Dawson M. D.
Published: July 2010

A nitrogen rate study was undertaken to determine the potential utility of the critical nutrient concept as a guide to N fertilization of winter wheat (Triticum aestivum L.), as part of a more extensive soil fertility investigation in western Oregon. This work on wheat was prompted by the need for a suitable diagnostic technique for determining more precisely the optimum levels of available N. Only limited information exists on the applicability of the critical nutrient concept or on critical levels of plant N in winter wheat, particularly the semidwarf types.

Top grain yield was reached after N application of 140 kg/ha, but there were no significant yield differences over the range from 84 to 224 kg/ha. Plant NO3‐N values in leaves and shoots at tillering, jointing, and boot stages of growth were increased significantly by the highest N increment of 224 kg/ha compared to the next lower N rate. In contrast to grain yield, the highest values for total N percentage in plant shoots at all the later growth stages and dry matter yield at the soft dough stage were obtained with the highest rate of applied N, which also produced the highest values for plant NO3‐N. Semidwarf wheat utilized the high N rate more efficiently for dry matter production than for grain yield, and high N fertility also increased grain protein percentage.

A graph of grain yield vs NO3‐N concentration in plant leaves at jointing showed a definite peak in grain yield at approximately 500 ppm NO3‐N in the leaves. Additional applied N very readily increased leaf NO3‐N considerably above 500 ppm and caused a slight, insignificant drop in grain yield. These results suggest the applicability of the critical nutrient concept to semidwarf wheat, and provide justification for additional work to establish more precisely the critical level for NO3‐N in wheat.
Influence of Seed Size and Depth of Planting on Seedling Emergence of Two Milkvetch Species1
Authors: Townsend C. E.
Published: July 2010

The relationship between seed size and seedling emergence was studied in cicer milkvetch (Astragalus cicer L.) and falcatus milkvetch (A. falcatus Lam.). Three sizes of seed of each species were planted at 1.3‐, 2.5‐, and 3.8‐cm depths in both the greenhouse and the field. The three seed sizes were designated as large, medium, and small. Sterilized soil was used in the greenhouse. Plantings were made at Ft. Collins and Akron, Colo, in fallowed soil.

In both the greenhouse and the field there were significant differences among depths of planting for seedling emergence. In the field, seedling emergence was influenced by soil moisture conditions at planting time and by subsequent precipitation. Usually, the optimum average planting depth under such variable conditions was 2.5 cm for both species. Shallower seeding would be satisfactory, however, if the soil surface was moist at planting time. Seedling emergence was good from all three depths in the greenhouse and was much better than in the field.

In the greenhouse, seedling emergence from the large seeds was significantly better than from the small seeds for cicer milkvetch. Differences among seed sizes for seedling emergence, however, were slight and nonsignificant for falcatus milkvetch.

The relationship between seed size and seedling emergence was variable for both species at both field locations. In two of four studies with each species a significantly greater number of seedlings was obtained from the large seeds than from the small seeds. The variability was attributed to soil moisture conditions. In general, there appeared to be more promise of improving seedling vigor through selection for large seeds in cicer milkvetch than in falcatus milkvetch.
Effect of Levels of Soil Potassium, Fertilizer Potassium, and Season on Yield and Ear Leaf Potassium Content of Corn Inbreds and Hybrids1
Authors: Gallaher Raymond N. , Parks W. L. , Josephson L. M.
Published: July 2010

Three corn (Zea mays L.) genotype groups including: inbreds T101, T105, T1ll, T115; their six possible single cross hybrids; and three double cross permutations were grown on a Hartsells loam soil at four rates of K fertilization for 3 years to evaluate their K requirements. The hybrids responded to higher rates of K fertilization than the inbreds. However, the leaf K values for the inbreds should be greater than the 1.5% critical level of hybrids for maximum yields. Seasonal variation in rainfall, temperature, and sunlight caused large differences in yield and ear leaf content of K. A quadratic regression model was fitted to yield of corn and percent K content of the ear leaf for each genotype group. Results indicated that the model would be more useful in accounting for variation in yield and K concentration for double‐cross hybrids than for single‐cross hybrids or inbreds. The linear effect of fertilizer K accounted for more yield and ear leaf K content differences than any other factor studied.
Effect of High Rates of N, P, K Fertilizer on Corn (Zea mays L.)1
Authors: Powell R. D. , Webb J. R.
Published: July 2010

This experiment was conducted to observe the effects on corn (Zea mays L.) grown on soils which received annual applications of fertilizer at rates above those normally recommended. Annual applications of high rates of N, P, and K fertilizer to Clarion‐Webster Soil Association soils in central (Ames) and north central (Kanawha) Iowa planted to corn produced variable yield results. Incremental rates of N, P, and K fertilizers up to 1,344, 504, and 1,008 kg/ha, (1,200, 450, and 900 lb/a), respectively, were applied annually for 3 consecutive years. The grain yields were analyzed statistically using analyses of variance and regression techniques. Three regression functions, a second order quadratic, a logarithmic to the base e, and a square root function were used to estimate the response surfaces and compared for goodness of fit. The yields were the dependent variable and the applied fertilizer nutrients were the independent variables.

It was observed that the logarithmic function fitted the data best in all three years at both sites. A second order quadratic yield prediction equation was developed which included independent variables for fertilizer N, K, N2, interactions of N with soil p, K with soil k and K with soil pH, a variable for soil n supplying power and a variable for measuring climatic influences. Increases in yields resulted from N fertilization. Yield decreases the final year were attributed to high salt concentrations and acid soil reactions. The surface soil pH decreased at a rate of 0.05 pH units per 112 kg/ha (100 lb/a) of N and yields decreased the final year as salt concentrations increased. Yields decreased at N rates above 224 kg/ha (200 lb/a) at the Ames site and above 448 kg/ha (400 lb/a) at the Kanawha site.
Relationships Between Dry Matter Yields and Concentrations of Zn and P in Young Corn Plants1
Authors: Terman G. L. , Giordano P. M. , Allen S. E.
Published: July 2010

Yield‐Zn or P concentration relationships were studied in corn (Zea mays L.) grown in several greenhouse pot experiments conducted to compare various rates and sources of Zn and P on soils deficient in these nutrients, Such relationships are important in proper interpretation of plant analysis results. The usual result was for corn forage yields to increase at a minimum Zn concentration of 7 to 9 ppm in the dry forage until P or other growth factor became limiting. Then yields leveled off and Zn concentrations increased at sufficiently high levels of applied Zn. Similarly, yields increased at a minimum P concentration near 0.10% until Zn or other growth factor became limiting; P concentrations then increased. Critical concentrations in the dry corn forage were estimated to be about 14 ppm of Zn and 0.14% P.