bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Seedling Age at Transplanting on Rice Performance1
Authors: Sanchez P. A. , L. N. Larrea
Published: July 2010

With the advent of high‐yielding rice (Oryza sativa L.) varieties on the cost of Peru, the question arose as to how these short‐statured plant types react to delays in transplanting, a common situation in the field because of uncertain water supply. A field experiment conducted in Lambayeque, Peru evaluated two short‐statured varieties, ‘IR8’ and ‘IR5,’ with the tall, traditional ‘Minabir’ variety at transplanting dates from 30 to 105 days after seeding and at three seedbed growth rates. IR8 produced the highest grain yield (12.0 tons/ha) when transplanted at 30 days after seeding. Yields decreased linearly at the rate of 125 kg/ha per day of delayed transplanting beyond 30 days. Minabir showed less‐pronounced yield decreases up to 75 days after seeding. Slowing seedbed growth of IR8 through water and N stress produced significant yield increases when transplanted at 75 and 90 days after seeding. Delayed transplanting reduced plant height and dry matter production, caused flowering shortly after transplanting in some cases, and decreased panicle production and the number of fertile grains per panicle. Seeding density had no effect on yields. The experiment showed that the short‐statured plant types are more sensitive to delays in transplanting than the tall ones, but that the new varieties can outyield the tall varieties when transplanted up to 90 days after seeding.
A Simple, Inexpensive Watre Bath for Precise Temperature Control
Authors: Spomer Louis A.
Published: July 2010

A simple, inexpensive water bath for precise laboratory temperature control is described. The bath was constructed from common materials at an actual cost of less than $35. Bath temperature is maintained slightly above ambient by a large volume mercury‐toluene thermoregulator and mechanical heat proportioner. This apparatus has maintained 20 C with maximum short fluctuations of ± 5 × 10−4 C and drift of + 2 × 10−3 C day−1 for continuous periods up to 25 days.
Effect of Delayed Thinning on Sorghum Growth and Yield1
Authors: Clegg Max D. , Maranville Jerry W.
Published: July 2010

An experiment was conducted to determine if a delay in thinning would adversely affect growth and yield of grain sorghum [Sorghum bicolor (L.) Moench]. Results showed that thinning should be performed as early as possible, preferably before plants reach 7.5 cm in height. Yield was reduced when thinning was delayed until plants were 15.0 cm to 23.0 cm in height. Stem diameter was reduced and seed size was increased when thinning was delayed until the plants had reached a height of over 31 cm. We suggest that when a delay in time of thinning is anticipated, planting to a desired population based on reliable laboratory germination tests may be preferable.
Carbon Dioxide and the Photosynthesis of Field Crops: A Metered Carbon Dioxide Release in Cotton Under Field Conditions1
Authors: Harper L. A. , Baker D. N. , Box J. E. , Hesketh J. D.
Published: July 2010

The benefits of increased carbon dioxide concentration in enclosed plant environments are well known, but there has been only limited experimentation with increasing carbon dioxide on a field scale. The purpose of this study was to artificially enrich a cotton (Gossypium hirsutum L.) crop with carbon dioxide using a known release rate and to determine the variation in canopy carbon dioxide concentration with respect to meteorological conditions.

Carbon dioxide was metered into the crop canopy while concentrations of carbon dioxide and other meteorological parameters in and above the canopy were measured. The crop had a leaf area index of 2.34, and the crop surface was aerodynamically rough. Turbulence caused considerable short‐term fluctuation in concentrations, but concentrations of 450 to 500 ppm at three‐fourths plant height were maintained with a release rate of 222.6 kg/ha/hour (198.6 Ib/acre/hour). Photosynthetic recovery of applied carbon dioxide was calculated from data obtained in the crop during its release and from data describing its behavior in a semiclosed plexiglass chamber just before the carbon dioxide release. Calculated recoveries ranged from 7 to 33% over a range of solar radiation levels from 205 to 1,095 W/m2. The release produced unexpectedly high carbon dioxide concentrations 4 m above the soil surface (due to vertical movement), and these concentrations varied little with windspeeds up to 200 cm/sec at the 150‐cm level. The daily net photosynthate production increased by an estimated 35%.
Germination of Dormant and Nondormant Rescuegrass Seed on the Thermogradient Plate1
Authors: Larsen Arnold L. , Montgillion Dorothy P. , Schroeder Eltora M.
Published: July 2010

Dormant and nondormant rescuegrass (Bromus catharticus Vahl.) seed were tested on the two‐way thermogradient plate to make a comprehensive comparison of their germination responses to alternating and constant temperatures within a range of 5 to 35 C. Nondormant seed germinated within 1 week at a constant temperature near 30 C and within 4 weeks over most of the temperatures above 15 C. Dormant seed did not germinate at constant temperatures. Moderate germination of dormant seeds was obtained at 4 weeks with alternating temperatures. Imbibition of dormant seed on 0.2% KNO3‐moistened blotters improved germination slightly. Clipping off the distal end of the caryopsis of dormant seed produced substantial germination at 3 weeks, but only at alternating temperatures. The combination of KNO3 and clipping resulted in a germination response by dormant seed at almost the same temperature range favorable for germinating nondormant seed.
Potassium Rate and Source Influences on Yield and Composition of Bromegrass Forage1
Authors: Laughlin Winston M. , Martin Paul F. , Smith Glenn R.
Published: July 2010

Objectives of the study were to determine K rate and source optima for bromegrass (Bromus inermis Leyss.) and effect of treatments on uptake and balance of K and other nutrient elements. A 2‐year field study compared six rates of two K sources on bromegrass grown on a K‐deficient area. Dry matter yields were determined and the forage analyzed for N, P, K, Ca, Mg, AI, Ba, B, Fe, S, Sr, Cu, Zn, and Mn concentration.

Each K rate increased K concentration of each cutting both years and decreased the Ca and Mg percentages. KCI increased K percentages, but had little effect on forage color, yield, or mineral uptake. Potassium sulfate increased both yields and mineral uptake. All K2SO4 rates eliminated the yellow foliage color. Each K increment of this K source increased the K and S percentages and uptake.

Results indicate that both K and S deficiencies were present. Of the applied N, P, K, and S brome foliage removed 70 to 194%, 36 to 76%, 109 to 155%, and 19 to 95%, respectively.
Phosphorus Availability of Some Philippine Rice Soils as Affected by Soil and Water Management Practices1
Authors: Sanchez P. A. , Briones A. M.
Published: July 2010

It is well established that flooding increases the availability of soil P to rice (Oryza sativa L.). Very little is known, however, on the influence of native soil P status or the type of water management used on the growth and P uptake of this crop. Also, the interaction between these two factors is unknown. In order to clarify these relationships, two greenhouse experiments were conducted on six representative Philippine lowland rice soils. The results indicate that the beneficial effects of flooding to rice vary with the level of available soil P, as measured by P uptake. In soils of high P availability, no differences were observed when rice was grown under constant flooding, on a partially oxidized profile or when flooding was delayed from 15 to 35 days after seeding. The latter two treatments produced lower yields and P uptake in comparison to constant flooding in soils of moderate to low P availability. When severe water stress occurred, rice growth, yield, and P uptake drastically decreased in all soils regardless of P availability. Puddling flooded soils has no effect on rice yields or P uptake at harvest regardless of soil P availability. Puddling unflooded soils severely decreased growth and responses to applied P when severe soil shrinkage took place. The benefits of flooding on P uptake by rice depend both on the available P level and the type of water management used.
Laboratory Evaluation of Quality in Subtropical Grasses: II. Genetic Variation Among Hemarthrias in In Vitro Digestion and Stem Morphology1
Authors: Schank S. C. , Klock M. A. , Moore J. E.
Published: July 2010

In vitro organic matter digestion (IVOMD) was studied in selfed progeny from four introductions of Hemarthria (limpograss) and in hybrids between two stoloniferous diploid lines. This grass genus occurs naturally in swampy areas of Africa, Asia, and South America, but introductions were not successfully introduced into the U.S. until 1964. Genetic improvement of the Hemarthrias was considered feasible because of their ability to persist under flooding, drought, and freezing temperatures. Information on the in vitro digestion of the limpograsses would also benefit long‐range plant breeding objectives by indicating relative differences between lines. IVOMD was significantly higher in a coarse‐stemmed tetraploid line from Africa than in any of the diploid lines studied. The stoloniferous diploid lines from Transvaal, Africa were intermediate in digestion but not significantly different from each other. F1 hybrid plants obtained from these two diploids were also intermediate in IVOMD. The least digestible Hemarthria studied was a bunch‐type, diploid introduction from Argentina. IVOMD at 5 weeks regrowth ranged from 54.3% in the Argentine diploid to 68.4% in the African tetraploid. In mature plants, IVOMD of the Argentine diploid averaged 38.5%; the African diploids, 56%; and the tetraploid, 66%. Studies of stem morphology revealed that the combined percentage area of vascular bundles for each cross section area was inversely related to IVOMD, indicating that structural differences can greatly reduce the digestibility of a grass.
Effects of Method of Harvest on Flue‐Cured Tobacco Part II. Chemical Components1
Authors: Brown G. W. , Terrill T. R.
Published: July 2010

Tobacco (Nicotiana tabacum L.) is subject to modification of chemical characteristics by alteration of production practices. If a suitable product can be provided for the tobacco manufacturers, utilizing the once‐over harvest approach, a much simpler and relatively less expensive harvesting machine could be developed and production costs could be markedly reduced.

Normal and once‐over methods of harvesting flue‐cured tobacco were evaluated for effects on the chemical characteristics of cured leaves. All plants were topped to 12, 16, or 20 leaves per plant. Stalk position data were compared within the three topping heights.

Lesser percentages of total N and total N‐soluble and a lower pH were evident in leaves grown in 1968 than those produced in 1969. As topping height was increased from 12 to 20 leaves per plant, percentages of total N, total N‐soluble, nicotine, and water‐soluble acids in the leaves decreased, while reducing sugars increased. These chemical changes were attributed to utilization of equivalent amounts of nitrogen for the development of greater number of leaves. Higher concentrations of total N, total N‐soluble, nicotine, and water‐soluble acids were recorded for leaves harvested by the normal method than when all leaves were removed in one harvest. Undoubtedly, overmature bottom leaves and immature top leaves, associated with the once‐over method, influenced the average chemical composition for the whole plant.

The nitrogenous constituents and water soluble acids increasel in leaves from bottom to top stalk positions except for percent alpha amino nitrogen. The pH of leaves decreased from bottom to top stalk positions. Overmature bottom and immature top leaves from the once‐over harvest contributed to difference in chemical composition of leaves at the upper and the lower stalk positions. When all leaves were harvested at one time, only bottom and top leaves appeared to be different in chemical composition from those presently being used by the tobacco trades.
Use of Potassium‐40 as an Evaluator of Animal Response in Grazing Trials1
Authors: Clark J. L. , Matches A. G. , Thompson G. B.
Published: July 2010

Our objective was to evaluate techniques for measuring the response of cattle grazing four pasture systems. The techniques employed were the use of the Whole Body Counter to measure potassium‐40 (40K) of animals to predict body composition, visual condition scores, and body weight. The condition score is a subjective score placed on the animal to estimate the amount of external flesh.

Pasture systems were composed of orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) for spring grazing and the round baled hay plus regrowth of orchardgrass‐Korean lespedeza (Lespedeza stipulacea Maxim.) and tall fescue for summer grazing.

Composition of gain was not influenced by pasture systems, and there was no change in condition score or FFB over the season. Approximately 66 to 74% of the gain was FFB and the remaining 26 to 34% represented body fat and gut content. There were no significant differences (P ≤ .05) in gain due to pasture systems. Since the estimation of body composition using 40K can be obtained without slaughtering the test animals, we believe the Whole Body Counter has much potential as a research tool in grazing research.
Leaf Angle, Leaf Area, and Corn (Zea mays L.) Yield1
Authors: Winter S. R. , Ohlrogge A. J.
Published: July 2010

Since canopy structure can be an important factor in determining the productivity of a plant community, these studies were undertaken to determine the influence of upright leaves, at various leaf area indexes (LAI) on the grain yield of highly productive, field‐grown corn (Zea mays L.).

Leaf area index was varied by changing plant population density. Leaf angles of the upper leaves were manipulated by mechanical means to change the leaf angle from roughly 45° to 10° or 15° from the vertical.

The response to upright leaves depended upon the LAI. At low LAI (below 3 or 4), upright leaves tended to decrease grain yield. At high LAI (5 and above), upright leaves tended to increase grain yield. The optimum LAI (population) for grain yield was always lower with the normal canopy structure than with upright leaves. When canopy types were compared for maximum yield (i.e. each considered at its optimum LAI), upright leaves outyielded the normal by only 0.4, 5.7, and 5.8% in 1968, 1969, and 1970, respectively. These slight yield differences are not statistically significant and occurred with LAI above those commonly found under conditions of commercial corn production in Indiana.

These results suggest that an upright leaf canopy similar to that tested would not be beneficial at present in Indiana or similar corn producing areas. If varieties are developed with a higher LAI at the population giving maximum yield and/or in an environment‐management situation capable of supporting a higher LAI, upright leaves might increase grain yield significantly.
Yield Response of Soybean Varieties Grown at Two Soil Moisture Stress Levels1
Authors: Mederski H. J. , Jeffers D. L.
Published: July 2010

Eight soybean [Glycine max (L.) Merrill] varieties in each of four maturity groups were grown to maturity at optimum and deficient soil moisture conditions to determine differences in varietal response to soil stress. A significant variety by stress level interaction on seed yield was detected among varieties in each of four maturity groups, indicating that the effect of soil moisture stress on yield varied among varieties.

Under high moisture stress conditions, the yield of the most stress resistant varieties was reduced about 20%, while the yield of the least stress‐resistant varieties was reduced about 40%. The absolute reduction in yield for the most stress‐sensitive varieties was approximately 1000 kg/ha, while the yield of the least stress‐sensitive varieties was reduced about 200 to 400 kg/ha.

Under conditions of optimum soil moisture, the difference in yield among varieties was large relative to the difference in yield produced under deficient moisture conditions. A low or nonstress soil moisture level permits greater genotypic expression, thereby increasing genotypic variance among varieties. A low soil moisture stress environment appears to be the optimum environment for selecting soybean yield attributes.
Effect of a Phytoplankton Culture on the Germination and Seedling Development of Barley, Sugar Beets, and Lettuce1
Authors: Davis Charles H. , Bigler E. Ray
Published: July 2010

Alteration of soil properties and plant growth by phytoplankton cultures has been reported many times as separate phenomena. An investigation of the interrelationship of alteration of soil properties and plant growth by a phytoplankton culture was undertaken. This report is confined to seedling development, emergence, and related yields.

The effect of various quantities of a Chlorophyta phytoplankton culture on seed germination, seedling development, and yield was evaluated in both the laboratory and field. In the laboratory, ‘Arivat’ barley (Hordeum vulgare L.) seedlings were grown in aqueous solutions of phytoplankton culture. Shoot length was increased by 102 and 103 ppm concentrations of the culture but was unchanged at 104 and 105 ppm. There was an inverse relationship between shoot length and shoot weight per unit length. In the field, barley seedling emergence was significantly increased by injecting undiluted phytoplankton culture with the seed at a rate of three liters per 240 m of row.

Preplant irrigation with a 103 ppm dilution of phytoplankton culture in the field increased sugar beet (Beta vulgaris L.) and lettuce (Lactuca sativa L.) seedling emergence. Subsequent post‐plant applications of the phytoplankton resulted in additional increase in seedling emergence. Increased production was found for the sugar beets at all levels of treatment. This further increase could not be allocated to either growth regulator or soil modification but could be the result of both acting at once.
Evaluation of Vigor Tests for Sorghum Seed1
Authors: Vanderlip R. L. , Mockel F. E. , Jan Halim
Published: July 2010

Standard germination tests often overestimate field performance of sorghum [Sorghum bicolor, (L.) Moench] seed. Seed from 60 seed lots were germinated following NH4CI treatment, NaOH treatment, and no treatment. Results from these tests, seed size, and tetrazolium staining were correlated with field stand establishment under four sets of conditions. Germination following NH4CI treatment gave highest and most consistent correlations with field stand establishment. Seed size and tetrazolium tests were poorly related to field stand establishment. Correlations among vigor tests, in general, were high, even with those that did not correlate well with field stand establishment. Thus vigor tests should be related to field stand establishment rather than to another vigor test.
Effects of Fertilizer on Root Strength of Sherman Big Bluegrass (Poa ampla Merr.)1
Authors: Haferkamp M. R. , Currie P. O.
Published: July 2010

Pulling of plants by grazing animals animals has been a common problem on ‘Sherman%’ big bluegrass (Poa ampla Merr.) pastures in Colorado. Fertilizers were applied to individual plants in a greenhouse study to evaluate their influence on plant resistance to pullup. The fertilizer treatments were 56 kg/ha N, 56 kg/ha P, or 56 kg/ha of each element as an N+P combination. Fertilizer treatments were applied to vernalized and nonvernalized plants grown in two soils.

Tensions required for pullup in the greenhouse were correlated with total root weight (r = .75**) and significantly increased with N fertilization. Plants fertilized with N produced more vegetative and reproductive shoots, tillers, foliage weight, and root system weight and length. Phosphorus fertilization produced a significant increase in vegetative and reproductive shoots, and a significant interaction between N and P was found for root system size and the amount of roots that were pulled from the soil with the plants.
Short Note on the “Wilting Phenomenon in Crop Plants”
Authors: Tomar V. S. , Childyal B. P.
Published: July 2010

In a greenhouse study diurnal variation in water deficit, resistance to water transport and the internal plantwater relations of rice (Oryza saliva L., Var. IR‐8) plants were determined to understand the phenomenon of wilting in rice plants. It seems that wilting occurs at a definite value of turgor pressure rather than the complete absence of turgor pressure and is associated with a marked change in the elastic property of the leaf tissue. The wilting may also be affected by the resistance to water movement in plant tissues. Wilting phenomenon is not related directly with the 15 bars soil moisture suction.
Phosphate Uptake and Distribution in Bush Bean Plants as Affected by Foliar Application of Naphthenate1
Authors: Severson John G. , Wort D. J.
Published: July 2010

A 0.5% solution of potassium naphthenates (KNap) was applied to the foliage of hydroponically grown 14‐ day‐old bush bean (Phaseolus vuigaris L., cultivar ‘Top Crop’) plants to determine the effect of this chemical mixture on the uptake and distribution of root‐fed 32P among leaf blade, stem, and root tissues. The plants were grown in eiither a phosphate‐free (−P plants) or a complete nutrient solution. The uptake of 32P was not changed by KNap treatment. The percentage distribution of 32P among the various plant organs, however, was markedly affected by the presence or absence of phosphate in the nutrient solution and by treatment. The enhanced translocation of 32P observed, especially in −P plants, may be associated in a casual way with the characteristic stimulation of metabolic processes in the aerial portions of naphthenate‐treated plants.
Effects of Temperature and Nitrogen Supply on Four Nitrogen Fractions in Barley1
Authors: Chowdhury I. R. , Zubriski J. C.
Published: July 2010

Distribution of four nitrogen fractions in tops and roots of 4‐ and 8‐week‐old barley (Hordeum vulgare L.) plants as influenced by two rates of nitrogen and three ambient temperatures during the latter half of growth period was studied in pot experiments. All plants were initially grown at 15.6 to 18.3 C for 4 weeks under two nitrogen treatments. Temperature variables were established on the plants during the last 4 weeks of growth. Temperatures tested in two sets of experiments were 7.2 to 8.9 C and 15.6 to 18.3 C, and 15.6 to 18.3 C and 26.6 to 27.7 C. Samples were analyzed for total, alcohol‐insoluble, alcohol‐soluble, and nitrate nitrogen. Highest dry matter was produced at 15.6 to 18.3 C. The 400‐mg N/pot yielded more total, alcohol‐insoluble, alcohol‐soluble, and nitrate nitrogen than the 20 mg N/pot. Yields of total and protein nitrogen in plants were approximately proportional to yield of dry matter, and percent total nitrogen in plants was inversely related to yield of dry matter. Alcohol soluble nitrogen yield was greater in plants grown at higher ambient temperatures in both experiments. In plants supplied with 400 mg N/pot, an above optimum temperature (26.6 to 27.7 C) caused a significant portion of the total nitrogen to be in alcohol‐soluble form. A large part of this alcohol‐soluble nitrogen was nitrate nitrogen. This alcohol‐soluble nitrogen is highly mobile and can be easily translocated to grain. These results corroborate field observations that temperatures above 27 C during the heading stage of barley plant restrict grain yields, even though protein percent remains high.
Effect of Level Terraces on Soil Moisture Content and Utilization by Corn1
Authors: Miller E. L. , Shrader W. D.
Published: July 2010

Field experiments were conducted to determine the effect of sod‐stabilized backslope level terraces on soil moisture content and the utilization of moisture by corn (Zea mays L.). Plots were located in the terrace interval and in terrace channel positions up‐slope from 9 different terraces, on a watershed, in the Ida‐Monona soil association area of southwestern Iowa. Periodic measurement of soil moisture in the root zone, daily observation of weather variables, and corn development and yield measurements were made for each plot and were used to evaluate soil moisture content and utilization by corn. Soil moisture amounts in the rooting zone were greater in terrace channels than in terrace interval positions on all sample dates, with differences ranging from 1.98 to 6.27 surface cm and averaging 5 cm in the surface 1.83 m of soil. Significant yield differences between positions occurred, and moisture‐stress intensity was a significant factor in explaining yield variation. Other factors that were significant in explaining the variation in yield were plant density and plant nitrogen and phosphorus contents. A yield‐response curve was developed, which characterized the relationship between corn yield and moisture stress intensity.
Management Effects on Persistence and Productivity of Birdsfoot Trefoil (Lotus corniculatus L.)1
Authors: Taylor T. H. , Templeton W. C. , Wyles J. W.
Published: July 2010

One of the deterrents to the use of birdsfoot trefoil (Lotus corniculatus L.) is the maintenance of acceptable stands after establishment. The principal objective of this study was to test the hypothesis that birdsfoot trefoil stands may be maintained through natural reseeding. Other objectives were aimed at evaluating varieties and determining the quality and quantity of herbage produced under different systems of management. Birdsfoot trefoil seed, represented by ‘Dawn,’ ‘Viking,’ and a Kentucky ecotype, were drilled into an old Kentucky bluegrass (Poa pratensis L.) sod in 1967, and the plantings were observed through the 1972 growing season. The second herbage crop of the natural‐reseeding plots was permitted to set seed in 1969 and 1970, but not in 1971 or 1972. Those plots had excellent trefoil stands at the end of 5 years, in contrast to plots that were prevented from reseeding (approximately 100 plants/m2 versus 20/m2, respectively). The hypothesis that good stands of trefoil may be maintained through natural reseeding was accepted. Losses in yields during the 2 years that reseeding was permitted were recovered during the following 2 years. Herbage produced during the reseeding process was of acceptable quality and could be especially important as pasturage for certain classes of livestock in midsummer. The ecotype was superior to Dawn and Viking in yield and persistence.
Comparative Phytotoxicity of Nitrapyrin and its Principal Metabolite, 6‐Chloropicolinic Acid
Authors: Geronimo J. , Smith L. L. , Stockdale G. D. , Goring C. A. I.
Published: July 2010

Previous laboratory studies have shown that nitrapyrin (2‐chloro‐6‐(trichloromethyl) pyridine) can produce phytotoxicity in certain plants. Nitrapyrin hydrolyzes in soil to 6‐chloropicolinic acid; however, the phytotoxic properties of the latter compound have not been compared with those of the former. Therefore, studies were conducted to compare the relative toxicity of nitrapyrin and 6‐chloropicolinic acid to the seedlings of various crop plants, to compare their phytotoxicity in a variety of soils, and to estimate if the soil concentration, of either chemical, required to produce significant growth reduction is less than recommended field application rates for nitrapyrin. Nitrapyrin was more toxic than 6‐chloropicolinic acid to the graminaceous species tested which included corn (Zea mays L.), sorghum (Sorghum vulgate L.), wheat (Triticum aestivum L.), and rice (Oryza sativa L.). 6‐Chloropicolinic acid was more toxic than nitrapyrin to the dicotyledenous species tested which included cotton (Gossypium hirsutum L.), sugar beet (Beta vulgaris L.), tomato (Lycopersicon esculentum L.), alfalfa (Medicago sativa L.), and soybean (Glycine max L.). The dicotyledenous species were more sensitive to both compounds than were the graminaceous species. All species tested except alfalfa and tomato tolerated soil concentrations of nitrapyrin estimated to be greater than the highest recommended field application rates. Nitrapyrin was more highly adsorbed and therefore detoxified to a greater extent than 6‐chloropicolinic acid when soil organic matter increased.
Effects of Copper Sources on Wheat and Soybeans Grown on Organic Soils1
Authors: Barnes J. S. , Cox F. R.
Published: July 2010

Optimum rates for and the residual effects of several new copper fertilizer materials have not been determined. Because the copper in these sources is complexed, usually with an organic ligand, it has been implied that they are more effective than copper sulfate.

The immediate and residual effectiveness of copper sulfate and several new chelated and/or complexed copper materials were compared to determine the optimum rate of application for each source. Field experiments were conducted on four acid, organic soils, each of which was severely deficient in copper. Wheat (Triticum aestivum L.) yields were increased with an increase in the rate applied to 2.8 kg Cu/ha at three locations and to 5.6 kg Cu/ha at the fourth. There was no difference in the nature of the response obtained among sources so all sources were considered equally effective when equivalent amounts of copper were used.

Soybeans [Glycine max (L.) Merr.] were double‐cropped behind wheat to determine the residual effect of these sources. Grain yields showed the same patterns of response to copper sources as were obtained with wheat. Plant analyses also revealed the same effects of copper applications as were obtained with grain yields. Distinct symptoms of copper deficiency developed in the control and low copper treatments in both crops.
Recovery, Residual Effects, and Fate of Nitrogen Fertilizer Sources in a Semiarid Region1
Authors: Power J. F. , Alessi J. , Reichman G. A. , Grunes D. L.
Published: July 2010

Information on recovery and eventual fate of fertilizer N applied to dryland crops in the northern Great Plains is needed to optimize economic returns and to minimize pollution hazards. In a field experiment at Mandan, N. Dak., four fertilizer N sources were applied to separate areas of corn (Zea mays L.) and bromegrass (Bromus inermis L.) for 4 years. From the fifth through seventh years, the two areas were uniformly seeded to barley (Hordeum vulgare L.) without additional N fertilization, until residual effects were no longer significant. Sources of N used were ammonium sulfate, ammonium nitrate, calcium nitrate, and urea, applied at either 55 or 110 kg/ha to Parshall fine sandy loam. Recovery of fertilizer N in corn plant tops was greatest for ammonium nitrate. Over 35% of the calcium nitrate and urea applied at 110 kg/ha of N to corn was leached below the root zone. Leaching of fertilizer N applied to bromegrass was insignificant. Except for urea, fertilizer N recovery by bromegrass from the other N sources was nearly equal and usually higher at 55 kg/ha. Residual growth responses were smaller from N applied to bromegrass than to corn. About 70 to 95% of the fertilizer N applied was accounted for by the end of the residual period, except for lower values for several of the urea treatments. Gaseous losses were probably high for urea surface broadcast on bromegrass at 110 kg/ha of N because only 47% could be accounted for and no residual effects were observed.
Relationships Between Seeding Dates and Environmental Variables, Seeding Methods, and Establishment of Small‐seeded Legumes1
Authors: Strand Rodney H. , Fribourg Henry A.
Published: July 2010

Precipitation, air and soil temperatures, soil moisture, and other environmental variables were measured daily for several weeks following the seeding of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus corniculatus L.) on 52 occasions. Regression analysis was used to determine the significance of these variables to stand establishment. Environmental variables explained much of the variation in initial legume populations, but variability in stand counts several months after seeding was explained primarily by the classification variable “seeding date,” rather than by the specific environmental variables associated with seeding dates.
Relationship between Soil Oxygen Diffusion Rate and Yield of Oats in a Coastal Alluvial Soil at Critical Level1
Authors: Saini G. R.
Published: July 2010

This note reports the effect of improved soil physical conditions, as characterized by oxygen diffusion rate (ODR), on the growth of oats (Avena sativa L.) at the critical soil salinity level (ECe = 5.0 mmhos cm−1).

In a coastal alluvial soil at critical salinity level (ECe = 5.0 mmhos cm−1), the yield of oats increased from 0.55 g/pot to 10.88 g/pot as ODR increased from 7.3 ✕ 10−8 g cm−2 min−1 to 31.0 ✕ 10−8 g cm−2 min−1. The root elongation of the plant also appeared to be related to ODR.
Performance of Soybeans (Glycine max (L.) Merrill) in the Wet Tropics Affected by N, P, and K1
Authors: Chesney H. A. D.
Published: July 2010

The cultivation of soybeans [Glycine max (L.) Merr.] in wet, humid, equatorial countries that have short days is relatively new. Little is known of the agronomic requirements for maximum production of the few adapted varieties.

Trials were set up on Arakaka clay loam (a yellow podzol, Typic Normudult) to determine soybean performance from 1) application of N, P, and K and 2) source of N. The variables were: nitrogen, 0, 22, and 44 kg/ha; phosphorus, 0, 29, and 58 kg/ha; and potassium, 0, 37 and 74 kg/ha. Urea, ammonium sulphate, and uramite were the sources of N.

Nitrogen significantly influenced yields only during one particularly wet season, when it caused a decrease. Potassium significantly increased yields only during this same period of heavy rainfall, with the effect being greater at the higher application of N. Yields were increased by P at all harvests up to application rates of 58 kg/ha for the first two crops and 29 kg/ha for subsequent crops. The N × K interaction was the only two‐factor interaction that consistently had any significant effect on yield. Source of N had no effect on yield. Oil and protein contents of the seeds were not influenced by N, P, or K.

Truog‐P in the soil was unaffected by the application of N or K. Fertilizer P and K increased their levels in the soil.

Results indicated clearly that adapted soybean varieties can be successfully cultivated in the wet tropics.
Effect of Row Spacing and Seeding Rate on Yield of Buckwheat1
Authors: Ali‐Khan S. T.
Published: July 2010

Very little experimental data are available on buckwheat (Fagopyrum sagittatum Gilib.) culture in North America. Therefore, to obtain information on the effect of row spacing and seeding rate a buckwheat cultivar, ‘Tokyo,’ and an experimental strain, CD 1370, were tested over a period of 4 years at two locations in Manitoba. Buckwheat was grown in rows 15, 30, and 45 cm apart at seeding rates varying from 22 to 60 kg/ha. The results indicate that varying row spacings and seeding rates did not affect appreciably the seed yields.
Competition of Common Milkweed with Sorghum1
Authors: Evetts L. L. , Burnside O. C.
Published: July 2010

Common milkweed (Asclepias syriaca L.) is a deep‐rooted perennial weed that has increased in occurrence in recent years and has caused much concern among landowners. Because it occurs frequently in dryland sorghum [Sorghum bicolor (L.) Moench], a 3‐year competition study using paired plots was conducted to determine the degree of yield loss caused by common milkweed. Sorghum yield and number of heads per hectare were significantly reduced by common milkweed competition each of the 3 years. Common milkweed reduced average yield by 21% and number of sorghum heads per hectare by 14%. Even low populations (less than 12,000 plants/ha) of common milkweed resulted in severe yield losses. Grain weight per head was significantly reduced by common milkweed competition in 1970 and 1972 but not in 1971. Competition had no effect on sorghum 500‐ seed weight in 1971 or 1972. Percentage protein (Kjeldahl method) of sorghum grain was significantly increased by competition in 1972 but not in 1971.
Sprinkler‐Induced Soil Temperature Changes Under Plant Cover1
Authors: Kohl R. A.
Published: July 2010

An experiment was conducted to determine the amount of soil temperature reduction to be expected from irrigating potatoes (Solanum tuberosum) at various intervals. Soil temperatures were measured at the 10‐cm depth under potato ridges with various amounts of plant cover. The mean daily soil temperature at the 10‐cm depth in a silt loam soil after 7 days following irrigation increased as much as 2 C above the daily irrigated plot with full cover and 4 C above the daily irrigated plot without cover. Similar soil temperature increases occurred in a loamy fine sand soil irrigated after 5 days which is the normal irrigation intervals for these soils.
Silica Concentrations in Grazed and Ungrazed Forage Species1
Authors: Morton B. C. , Jutras M. W.
Published: July 2010

The presence of silica (SiO2) has been reported as significantly affecting the nutritional value of forages. This study was conducted to determine the SiO2 concentration in forage samples collected monthly from 2‐ha paddocks of ungrazed tall fescue (Festuca arundinacea Schreb.) and ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) as they matured, and to determine the monthly SiO2 concentrations of vegetative tall fescue, tall fescue‐‘Ladino’ clover (Trifolium repens L.), orchardgrass (Dactylis glomerata L.), orchardgrass‐Ladino clover, Coastal bermudagrass, and stockpiled tall fescue which were incorporated into four grazing systems. Samples representative of forage grazed by yearling beef heifers were collected monthly from caged areas to determine the SiO2 levels.

The SiO2 concentrations ranged from 0.30 to 2.65% in dry matter and exhibited variations between species and from month to month within a given species. Silica accumulated rapidly in the forage tissue early in the growing season and thereafter concentrations remained relatively constant. Actively growing forages maintained in a vegetative state by grazing did not exhibit appreciable monthly differences in SiO2 concentration. Increases in SiO2 concentration were noted during winter dormancy. These results indicate the need for further study of the hypothesis that SiO2 can be used to reveal the nutritive value of a forage, particularly the nutritive value of grazed forages.
Growth Response of Crops to Depth and Salinity of Ground Water, and Soil Submergence. I. Wheat (Triticum aestivum L.)1
Authors: Chaudhary T. N. , Bhatnagar V. K. , Prihar S. S.
Published: July 2010

Information on crop response to depth and salinity of ground water and soil submergence is important for planning drainage and optimizing crop production. Response of a semidwarf wheat (Triticum aestivum L.) to four depths (60, 90, 120, and 150 cm) and three salinities (EC 0.5, 2.9, and 5.2 mmho/cm) of ground water was studied in lysimeters filled with silt loam soil during 1970–71 and 1971–72. The plants were irrigated with water of EC 0.5 mmho/cm when the lysimeters with a 150‐cm water table depth indicated a tension of 0.5 bar at a 75‐cm depth. Ground water of EC 0.5 mmho/cm at 60 and 90‐cm depths gave highest yields. Comparable increase in the salinity of ground water caused greater reduction in yield with shallow water tables than with deep water tables. It is indicated that critical depth of ground water, for optimum crop production, would vary in relation to its salinity.

Growth and yield response of wheat to soil submergence was investigated in another set of lysimeters with water table at 60 cm. Soil submergence up to 2 days did not affect growth. It decreased yield gradually up to 5 days and sharply thereafter. Prolonged soil submergence reduced protein content in the grain as indexed by N content. To ensure optimum grain quality and production, excess water must be drained from the root zone within 3 days of submergence.
Relationship Between Corn Yield and Plant Nutrient Content1
Authors: Walker W. M. , Peck T. R.
Published: July 2010

The purpose of this study was to determine the relationship between corn (Zea mays L.) yield and the nutrient content of corn plants at three stages of growth. Experiments were conducted at two locations. For purposes of this research nutrient content refers to total amount of one or more nutrients contained in the corn plant or some part of it. Most previous research has involved relationships between nutrient concentrations (percentages or parts per million) and corn yield rather than between total amount of nutrients in the plant and corn yield.

Corn yields were regressed on the N, P, K, Ca, Mg, Mn, B, Cu, and Zn content of corn plants averaging 25 cm in height and 76 cm in height, and of different plant parts at early tassel. Previous research had regressed yields on nutrient concentrations at the same stages of growth. It was found that in terms of R2 values more precise yield predictions could be made from the nutrient content of whole plants at early growth stages than from nutrient concentrations. At early tassel there was little advantage in using nutrient content for predicting yields when compared to nutrient concentration in different plant parts. These results suggest that early in the life of the corn plant, nutrient content may be a better tool for predicting yields and thus diagnosing possible deficiencies than nutrient concentration.

Various correlations between cations in different plant parts were also investigated. Negative correlations between certain cations in plant tissue are frequently reported, but they most often involve concentrations in some specific part of the corn plant at early tassel. In this study negative correlations were observed between percent K and percent Mg in whole plants and in different plant parts. A negative correlation between percent Ca and percent K was observed in leaves but not in stalks. A positive correlation between the content of Ca and K was observed in all plant parts and growth stages, but there was no consistent correlation between K and Mg content over all growth stages and plant parts.
Effects of Diet of Fistulated Steer on In Vitro and In Vivo Nylon Bag Digestibility of Forage‐Corn Mixtures1
Authors: Monson Warren G. , Utley Phillip R.
Published: July 2010

We evaluate dry matter digestibility of several thousand forage samples annually. This study was designed to assess the effects of a major diet change of a fistulated steer on in vitro and in vivo nylon bag dry matter digestibility estimates of several forages and forage‐corn (Zea mays L.) mixtures. The major variable was a change in the diet of the fistulated steer from ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) hay to a concentrate ration of corn (72%), peanut (Arachis hypogaea L.) hulls (20%), and protein supplement (8%). The correlation between in vitro dry matter digestion values on samples utilizing inoculum from a steer fed the two diets was .97. The correlation coefficient for the nylon bag dry matter digestion values for samples digested in a recipient steer fed the two diets was .95. The data indicate that a diet change need not interrupt a forage screening program aimed at relative ranking of substrate but could jeopardize nutritive evaluations.
Establishment of Tall Fescue and Koleagrass with Rye as a Companion Forage Crop1
Authors: Hoveland C. S. , McCormick R. F.
Published: July 2010

Autumn‐planted tall fescue (Festuca arundinacea Schreb.) in the lower southeastern United States results in low establishment‐year forage production. Rye (Secale cereale L.) as a companion crop should improve winter forage yield but may be harmful to stands of the perennial grasses. To study this problem, ‘Kentucky 31’ tall fescue and ‘Perla’ koleagrass (Phalaris aquatica L., previously classified as P. tuberosa var. hirtiglumis Batt. and Trab.) were planted on a new area each year for 3 years, both alone and in association with ‘Wren's Abruzzi’ rye.

Rye, planted with tall fescue or kolea, increased total establishment‐year forage yield (October to May) nearly 150% over that of the perennial grasses seeded alone. Autumn and winter (October to mid‐March) production of the rye‐perennial grass mixtures were 500% greater than the perennial grasses planted alone. Second‐year stands of tall fescue were unaffected and kolea was reduced by seeding with rye the previous year. Second‐year forage yields (August to July) were reduced 25% on tall fescue and 62% on kolea when established with rye. However, most of the tall fescue yield reduction occurred during August and September when forage quality was low. Broadcast and row plantings gave similar results with both perennial species.

It was concluded that rye could be planted with tall fescue to increase establishment‐year forage yields and still result in good tall fescue stands. Establishment of koleagrass with rye was unsatisfactory.
Root Development and Nutrient Uptake by Corn Grown in Solution Culture1
Authors: Warncke D. D. , Barber S. A.
Published: July 2010

Although nutrient uptake by young corn (Zea mays L.) roots from solution culture has been extensively studied, little information is available on the rate of root development and nutrient uptake during the entire development of the corn plant. Corn root growth rate, the nutrient content of the root and shoot, and the nutrient uptake rate were studied for five stages of development of corn plants growing in solution culture in the greenhouse. The data were compared with similar observations in the field.

Corn root length increased exponentially with time until the tasseling stage, as also occurred in the field. Beyond this stage root length in solution culture increased slowly. The proportion of N, P, K, Ca, and Mg present in the roots ranged from 0.11 to 0.22 and averaged 0.15 of the total. Nutrient uptake rate per meter of root was greatest for the first growth stage and decreased with plant age. Rates of uptake per meter of root were similar to those obtained in the field except that the rates for the youngest plants in solution culture were slower than for similar plants grown in the field.
Some Effects of Subirrigation on Bentgrass During Heat Stress in the Field1
Authors: Krans Jeffrey V. , Johnson Gordon V.
Published: July 2010

The management of bentgrass (Agrostis spp.) in the southwestern United States presents numerous problems to the grower because of the long period of high summer temperatures associated with this region. Prolonged high temperature stress often results in turfgrass injury from dessication, disease, or insect damage. This study was conducted to determine if the adverse effects of heat stress could be alleviated by subirrigation.

A field study was conducted to evaluate the merits of subirrigation on Agrostis palustris Huds. during a 4‐month period of heat stress. Effects were evaluated from clipping yields, chlorophyll content and root distribution. Three irrigation treatments were applied to artificial soils of washed mortar sand and a sand‐soil mixture. Temperature adversely affected clipping yields and chlorophyll content during excessive heat stress (30 to 35 C) early in the summer. Clipping yields remained low, but color gradually darkened following the initial stress period. Reduction in clipping yields was greater for the mix than sand. Chlorophyll content was not consistently affected by the kind of soil. Sprinkle irrigation and subirrigation from a fluctuating water table resulted in similar yields, whereas subirrigation from a single stable water table at 30 cm produced significantly lower yields. Subirrigated plots also had significantly lower chlorophyll production than sprinkle‐irrigated plots. The reduced color associated with subirrigated treatments apparently resulted from poor aeration. Root development was deeper (45 cm vs. 30 cm) and total mass greater in the sand than in the mix. This difference was attributed to a greater % air‐filled pore space and lower N levels in the sand. Differences in root mass between irrigation treatments were related to aeration differences in subirrigated plots and N nutrition in surface irrigated treatments. Sprinkler‐irrigated plots required periodic syringing while temporary wilting was not observed on subirrigation plots.