bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Subsurface Asphalt Layers on Corn and Tomato Root Systems1
Authors: Saxena G. K. , Hammond L. C. , Robertson W. K.
Published: July 2010

In recent years several reports have indicated an improved crop production on droughty sands treated with a subsurface asphalt layer at depths of about 60 cm. Root growth in these modified soil profiles has not been investigated. This study was initiated to determine the nature and reason of any influence of a subsurface asphalt layer on root growth and distribution in the soil profile.

Observations of root distributions of sweet corn (Zea mays L. var. ‘Rugosa’) and tomato (Lycopersicon esculentum Mill. var. ‘Commune’) were made in freshly dug pits. Root sections in and out of the asphalt layer were photographed and examined microscopically for morphological effects. The “line‐intercept” method was used to obtain quantitative measurements of root concentration (cm root/cc soil) of field corn (Zea mays L).

Tomato roots in the asphalt layer were larger in diameter and showed damage to cells in the cortex. Rooting of all crops was less extensive in soil below the asphalt layer than in soil at the same depth without the asphalt. Concentration of corn roots in the top 60 cm of soil averaged 1.6, 1.7, 2.0, and 2.2 cm/cc for the following respective treatments: control, control with irrigation, asphalt layer, and asphalt layer with irrigation. This compensation effect would limit any reduction in value of the root‐resistant asphalt layer to situations of low rainfall without irrigation.
Factors Affecting the Development of Flue‐Cured Tobacco Grown in Artificial Environments: IV. Effects of Carbon Dioxide Depletion and Light Intensity1
Authors: Raper C. David , Downs R. J.
Published: July 2010

Plants grown in controlled‐environment rooms are usually under a CO2 stress that the so‐called “make‐up air systems” do little or nothing to alleviate. Tobacco (Nicotiana tabacum L.) rapidly depletes the CO2 from 400 ppm (v/v) ambient level to 200 ppm. This report evaluates the effects of this CO2 stress by comparison with plants grown in an atmosphere where CO2 was maintained at the ambient 400 ppm level by supplemental CO2. Light intensities of 215, 322, and 450 hlx were superimposed on both CO2 regimes. Plant development was evaluated by physical and chemical properties of mature leaves and has been compared not only among the imposed treatment conditions, but also with the development that occurs in a natural field environment.

Several abnormalities of tobacco were noted under CO2 stress. These include: a low concentration of reducing sugars in the cured leaves, presumably reflective of low soluble carbohydrate accumulation in mature leaves; reduced internode elongation; and epinasty of leaves during maturation. A reduced dry matter accumulation in aerial organs, concomitant with the reduced internode growth, was recorded under the CO2 stress. Only small differences between CO2 levels occurred for dry matter accumulation in leaf tissue.

Decreased light intensity increased accumulation of nitrogen and potassium by the plants independent of CO2 level. Most of this increase was attributed to actively expanding tissue, in this case to growth of secondary meristems.
Grain Sorghum Yields in One‐Row and Two‐Row Plots1
Authors: Ross W. M.
Published: July 2010

Four combine grain sorghum hybrids, Sorghum bicolor (L.) Moench, were yield tested for 5 years in west‐central Kansas in one‐row and in two‐row plots with each hybrid as a border to determine relative reliability of data from the two plot types. Though ranks of hybrids remained the same, regardless of plot type or border, yields of individual hybrids varied from −5 to +10% in single‐row plots and from −2 to +5% in two‐row plots depending on the border rows. In addition, a strongly competitive hybrid, like RS 610 yielded more when bordered by some other hybrid, and a weakly competitive hybrid, like RS 650, yielded less. Average differences were: RS 610 (1‐row plots, 290 kg/ha), RS 610 (2‐row, 100), RS 650 (l‐row, −130), and RS 650 (2‐row, −20).

Two‐row plots, and sometimes multiple rows, are deemed desirable for refined experiments and for tests in areas where growing conditions may be suboptimum. One‐row plots appear to be practical for routine programs involving high entry numbers, for increasing replications, or for testing at additional locations without enlarging total seed and land requirements.
Agronomic Investigations Using Continuous Function Experimental Designs—Nitrogen Fertilization of Sweet Corn1
Authors: Fox R. L.
Published: July 2010

Simple experimental designs are needed for exploratory field studies and for generating data for well defined yield response curves and surfaces. A design was developed by which a variable was increased in many small increments along corn (Zea mays L.) rows. Individual plants were handled as plots. Sweet corn was grown in rows 12 m long, along which rates of N fertilization increased in 40 increments from 0 to 220 kg/ha. Replication was obtained by repeating the layout but rotating it through 180 degrees. “Border effects” along the row could be ignored because the incremental change of applied N was very small and because the N rate increased in one direction and decreased in the other. Because there are many experimental points it was possible to show that low rates of N produced a “diluting effect” on leaf N, that N deficiency symptoms disappeared and second ear develop ment began at about 140 kg N/ha, that lower corn leaves are the most sensitive indicators of the N status of corn, and that yield response to applied N was linear to 200 kg/ha of N applied. If a second factor is varied at right angles to the first, a well defined response surface can be obtained.
Growth and Chemical Composition of Crownvetch as Affected by Lime, Boron, Soil Source, and Temperature Regime1
Authors: Bennett O. L. , Mathias E. L.
Published: July 2010

Crownvetch (Coronilla varia L.) was grown in environmental chambers at three temperature regimes using lime and boron applications separately and in combination on Gilpin shaly silt loam soil from north and south exposures. Temperature regimes were (T1) 18.3 C day — 12.8 C night; (T2) 23.9 C day — 18.3 C night; and (T3) 29.4 C day — 23.9 C night. Liming increased both root and top growth in all instances There was a significant plant growth response to temperature regime, soil from different exposures, lime, and temperature × lime interaction. Application of boron increased yields of plants grown on soil from the northern exposure but not on soil from the southern exposure. Application of boron, with or without lime, increased boron content of crownvetch, but lime applications reduced the amount of uptake. The T2 temperature regime was optimum for top growth but T1 was optimum for root growth. Soil pH ranged from 4 to 5.6 by the end of the study; growth of crownvetch did not appear to be impaired at these low pH values when lime had been applied.

Liming increased Ca but reduced P, K, Mg, Mn, Zn, B, Na, and Cu concentrations of plants. Application of boron to soil increased B and Fe concentrations of plants, especially at T2 and T3. Phosphorus concentration of plants was higher at T2 and T3 than at T1; however, Fe, Al, and Mg concentrations generally decreased with increasing temperature.
Spraying Alfalfa Hay with Water Before Baling to Minimize Harvesting Losses1
Authors: Anderson M. J. , Mickelsen C. H.
Published: July 2010

Dry alfalfa (Medicago sativa L.) hay was sprayed with a fine mist of water before baling to determine if harvest losses could be reduced to the same level as dew‐moistened hay. Three studies were conducted. Study I compared hay that was dry, dew‐moistened, and sprayed with 1 liter of water per 4 m (1–4) of windrow. Study II compared the 1–4 rate to 1 liter of water per 2 m (1–2) of windrow. Spraying preceded baling by 5 to 10 minutes in studies I and II. Study III compared dry, dew‐moistened, and sprayed at the 1–4 rate 0, 5 and 10 minutes before baling. Strips over 150 m long were harvested with a 3.65‐m swather‐conditioner. Each swath was a replicate. There were 10, 6, and 11 replicates per study, respectively. Yields, chemical composition, and digestibility were determined. Digestibility and yields of dry matter (DM) and digestible DM were approximately 4, 1, and 6% higher for the sprayed hay than for the dry hay in study I. Yield of sprayed hay and dew‐moistened hay were comparable. Yields were slightly higher for the 1–2 spraying rate than for the 1‐4 rate but the differences were not significant. In study III yields were not as high for sprayed hay as for dew‐moistened hay. The 0 and 5 minute spray treatments had higher yields than the dry hay. We believe a higher spraying level should have been applied in study III. Spraying hay with water will reduce DM losses and increase nutritive value when dry, brittle hay is harvested.
Influence of Applied Nitrogen on the Performance of 23 Orchardgrass (Dactylis glomerata L.) Varieties1
Authors: Frank K. D. , Pesek John
Published: July 2010

Orchardgrass (Dactylis glomerata L.) pastures and the N fertilization of these pastures are important to beef cattle production in the humid and subhumid parts of the United States. Nitrogen in excess of 200 kg/ha per year is required for economic yields. We studied the influence of two levels of N (270 and 540 kg/ha per year) on forage yield, concentration of NO3‐N, N, P, and K or 23 orchardgrass varieties from diverse areas of the world.

NO3‐N, total N, percentage of P, and forage yield were affected significantly by applied N, varieties, and time after application of N. Percentage of K was influenced by varieties and time after application of N. Percentage of P in the forage tended to decline with increased N, but remained above the level considered adequate for optimum production.

The late‐maturing varieties, as a group, contained higher concentrations of NO3‐N and total N, and produced less total dry matter than did medium‐ and early‐maturing varieties. Variability also existed among varieties within a maturity group, and more variability was observed at the higher rate of applied N. Concentration of NO3‐N at the high rate of N varied from 0.3 to 0.8%.

Positive linear relationships were observed between NO3‐N content and total N content for the individual forage harvests.
A Cost‐Benefit Evaluation of Controlled‐Environment Research Versus Field Research1
Authors: Raper C. David
Published: July 2010

To evaluate the comparative costs of controlled‐environment and field research, a ledger has been formulated to consider the base expenditures—those expenses incurred in the routine operation of the field and controlled‐environment facilities—and the variable expenditures—those incurred in the acquisition of samples and the various chemical, physical, and morphological analyses dictated by the needs of a particular investigation. For a comparable experiment, the base cost of growth‐chamber space in the North Carolina State University Phytotron is more than fivefold the base cost for field‐acreage. This relatively high base cost for controlled‐environment research is offset by a greater variable cost encountered with field research.

Examination of the comparative cost‐analysis reveals a strategy for substantially reducing the cost‐benefit ratio for agricultural research by judicious use of controlled‐environment research in complement to field research. This strategy is discussed.
Nutritive Value of Alfalfa Selected for Saponin1
Authors: Anderson M. J. , Pedersen M. W. , Waldo Dale R.
Published: July 2010

Studies have shown that saponin concentration is affected by alfalfa (Medicago sativa L.) variety and is highly heritable. The study herein reconsidered chemical composition of strains selected for different saponin contents and considered the influence of saponin concentration on in vitro dry matter disappearance.

Eighteen strains of alfalfa were harvested three times during the growing season. These strains had been selected within six varieties (‘DuPuits,’ ‘Ladak,’ ‘Lahontan,’ ‘Ranger,’ ‘Uinta,’ and ‘Vernal’) to decrease or increase saponin content. Six replicates were employed. Samples were analyzed for in vitro dry matter disappearance (DMD), crude protein, cell wall constituents, acid detergent fiber, and acid detergent lignin. Highly significant differences (P<.01) in DMD were observed for strains, cuttings, and cuttings × strains. Correlations between saponin and DMD were overall (−.20), common within variety (−.25), and common within cutting (.19). These low correlations ascribe saponin only a very minor role in affecting the digestibility component of nutritive value.
Photosynthetic Efficiency of Sorghum Genotypes After Head Emergence1
Authors: Krishnamurthy K. , Rajashekara B. G. , Jagannath M. K. , Gowda A. Bomme , Raghunatha G. , Venugopal N.
Published: July 2010

The three growth parameters measured after heademergence, net assimilation rate (NAR) based on total dry matter and leaf area/plant, leaf area duration (D), and grain‐leaf ratio (G), were studied in several field experiments on sorghum [Sorghum bicolor (L.) Moench] to evaluate their relationship to yield. Each growth component was correlated with grain yield. Both D and G were found to vary with genotype, as well as with changes in plant population and levels of nitrogen. Grain‐leaf ratio was found to be greater in a new cross, MS 2219 × IS 3541, than in hybrid CSH‐1. ‘Swarna,’ a genotype with erect leaves, was found to have higher G than CSH‐1. Increasing the plant population from 133,000 to 177,000 plants/ha increased D, but reduced G. Increasing the levels of nitrogen from 60 to 120 and 180 kg/ha increased only D. Both G and D were correlated with grain yield. Nevertheless, the high multiple correlation of yield with G and NAR stressed the importance of NAR.
Influence of Water Management Through Irrigation and a Subsurface Asphalt Layer on Seasonal Growth and Nutrient Uptake of Corn1
Authors: Robertson W. K. , Hammond L. C. , Saxena G. K. , Lundy H. W.
Published: July 2010

During the past 5 years improved water management of droughty sandy soils has been attained by constructing, at a depth of 60 cm in the soil profile, a continuous layer of asphalt about 0.3 cm thick. Plots (60.9 × 60.9 m) on a Typic Quartzipsamment (Lakeland fine sand) were treated in 1967 and used in 1970 and 1971 to measure seasonal growth and nutrient uptake of corn (Zeamays L.) in response to the following water management treatments: check, irrigation, asphalt layer, and irrigation with asphalt layer. Responses to fertilizer rate and plant population were also obtained.

The asphalt layer increased corn fodder yields above the check and irrigation treatments during the first 11 weeks when moisture stress was moderate. At this time an 11‐day drought caused a severe water stress on the check and asphalt layer treatments resulting in grain yields of 5140 and 5020 kg/ha, respectively, whereas the irrigated and irrigated with asphalt layer treatments produced 7590 and 8164 kg/ha, respectively. The aphalt layer reduced the need for supplemental water and maintained or improved the N and K contents of corn fodder during periods of moderate stress. Fertilizer rates did not affect corn grain yield significantly. The lowest rate, 224‐73‐187 kg/ha of N‐P‐K, produced 6378 kg/ha. The highest yield, 681.5 kg/ha of grain, was obtained for the plant population density of 47,000 plant/ha as compared to 5994 kg/ha and 6552 kg/ha for 32,000 and 81,000 plants/ha, respectively.

The seasonal response of corn to water management showed that the asphalt layer system was effective in increasing water use efficiency in well‐drained sandy soils.
Postfertilization Changes in Concentration of Nitrate Nitrogen in Kentucky Bluegrass and Tall Fescue Herbage1
Authors: Hojjati S. M. , Templeton W. C. , Taylor T. H. , McKean H. E. , Byars J.
Published: July 2010

A continuing deterrent to increased use of N fertilizers on humid‐zone grasslands is the possibility of deleterious nutritive effects resulting from ingestion by animals of herbage high in nitrate. Studies were initiated to obtain data on the pattern of NO3‐N accumulation and disappearance in Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.) herbage following spring fertilization with four levels of N.

Identical experiments of split‐plot design were conducted on adjacent areas of the two grasses. Ammonium nitrate was applied to supply 50, 100, 150, or 200 kg/ha of N. The N treatments were replicated hi time, with a spacing of 3 weeks between replications. Herbage samples were collected at weekly intervals for a period of 6 weeks following fertilization. Dry matter yields and concentration of total N and NO3‐N in the herbage were determined.

The pattern of accumulation and disappearance of NO3‐N appeared to be similar for the two grasses. Accumulation peaks were almost always reached within 14 days following fertilization, after which the values gradually declined. Length of time required for dissipation of the effect of N application on NO3‐N levels was directly related to quantity of fertilizer used but also appeared to be dependent on the species of grass. In two of the three growth periods, for example, the concentrations of NO3‐N in Kentucky bluegrass receiving 200 kg/ha of N decreased to values below 2,000 ppm within 4 weeks after fertilization. In contrast, tall fescue herbage consistently contained 2,000 ppm or more of NO3‐N 6 weeks after fertilization at the 200 kg/ha rate.

Coefficients of variation for ppm of NO3‐N were 22.5% for Kentucky bluegrass and 21.1% for tall fescue; the C.V. for percent total N was 4.4% in bluegrass and 4.3% in fescue. Peak NO3‐N levels and maximum total‐N values occurred at essentially the same time.

Some implications of the findings are discussed with respect to utilization of N‐fertilized grasslands and the use of herbage NO3‐N levels for predicting response of grasslands to N fertilization.
Effect of Rate and Date of Seeding Shoshoni Winter Wheat on Soil Moisture Depletion1
Authors: Kolp B. J. , Sackett R. G. , Bohnenblust K. E. , Roehrkasse G. P.
Published: July 2010

Some growers in southeastern Wyoming plant winter wheat (Triticum aestivum L.) 2 weeks earlier than the recommended planting date, a procedure that utilizes more moisture than necessary for stand establishment. This experiment was designed to determine the extent to which high rates and early planting of winter wheat depleted soil moisture.

‘Shoshoni’ winter wheat was planted at seeding rates of 17, 34, 50, and 67 kg/ha on four seeding dates, August 19, August 26, September 4, and September 11, 1965. In mid‐August, November, April, and after harvest soil moisture was measured to a depth of 122 cm using the neutron probe. Moisture depletion during the fall, winter, and spring growing periods was calculated.

During stand establishment, the wheat planted August 19 depleted soil moisture significantly more than wheat planted September 4 and 11, and the wheat seeded at the rates of 34, 50, and 67 kg/ha depleted soil moisture significantly more than that at the 17 kg/ha rate.

Kernel protein content of wheat harvested from planting dates August 19, August 26, September 4, and September 11 was 12.2, 13.3, 13.2, and 14.2% respectively. There were no significant differences in grain yield attributed to planting dates or rates.

During the test period adequate spring moisture was received. During years of low spring precipitation, conservation of moisture by planting on the recommended date or later could be important.
Establishment of Centipedegrass and St. Augustine Grass with the Aid of Chemicals1
Authors: Johnson B. J.
Published: July 2010

The establishment of Centipedegrass (Eremochloa ophiuroides (Munro) Hack.) and St. Augustine grass (Stenotaphrum secundatum (Walt.) Kuntze) is often slow because weed competition may be severe. An experiment was conducted to determine the effects of single and repeated treatments of atrazine (2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine) and simazine (2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine) on the establishment of these two species. Single treatments of simazine and atrazine at 1.12 kg/ha applied immediately following sprigging satisfactorily controlled grassy weeds and increased percent ground cover. Except for atrazine on St. Augustine grass, herbicide treatments caused early growth retardation without reducing ground cover at the end of the season. The desirability in appearance of the turf was not generally affected by either chemical at the rates used.
Sudangrass and Sudangrass Hybrids Responses to Row Spacing and Plant Maturity on Yields and Chemical Composition1
Authors: Worker George F.
Published: July 2010

The purpose of this study was to determine the effect of row spacing and stage of maturity at harvest on dry matter production and the chemical composition under desert condition of Sudangrass [Sorghum Sudanese (Piper) Stapf., var. ‘Piper’], sorghum‐sudangrass hybrid [Sorghum bicolor (L.) Moench × Sorghum Sudanese (Piper) Stapf., var. ‘Sudax SX‐11’], and a Sudangrass hybrid (var. ‘Trudan 1’). The evaluation was made during a long growing season, 224 days, at four row spacings and two maturity stages, involving three and four cuttings at flowering stage and six and seven cuttings at pasture stage (1965 and 1966, respectively).

Dry matter production by all cultivars at both harvest stages significantly decreased as row spacing was increased from 35.6 to 88‐9 cm. Total dry matter production was highest with harvest at the flowering stage, 27.47, 28.16, and 27.11 metric tons/ha for sudangrass, Sudangrass hybrid, and sorghum‐sudangrass hybrid, respectively. Dry matter at the pasture stage was significantly higher for the sudangrass variety than for the hybrids.

Crude protein production increased with row spacing at the pasture stage and decreased with row spacing at the flowering stage. Row spacing did not affect fiber, fat or ash production. Fiber was higher when cut at the flowering stage and lowest in the sudangrass hybrid. Dry matter production of all cultivars significantly decreased as row spacing increased.
Use of Energy‐Absorbing Materials to Permit Turf Growth in Heavily Trafficked Areas1
Authors: Wood Glen M.
Published: July 2010

Soil compaction, with leaf abrasion of secondary importance, was concluded to be primarily responsible for the inability of grass to survive in heavily travelled footpaths. Several materials were used in the construction of a grassed walk designed to absorb traffic energy, eliminate compaction and afford wear protection to intermingled grasses. Inverted Coke bottles, bricks, and crushed stone were the experimental materials. The growth of the p i s s was best in the bottle area. However, the bottles were slippery when wet and presented some hazard. Orientation of the bricks to direction of traffic was found to be important. Bricks perpendicular to direction of travel were much more satisfactory than those placed parallel. ‘Manhattan’ perennial ryegrass (Lolium perenne L.) and ‘Merion,’ ‘Pennstar,’ ‘Nugget,’ and Fylking' bluegrasses (Poa pratensis L.) were evaluated as a mixture in these trials. An excellent sod was maintained with the bricks and bottles but not with the crushed stone.
Use of Pressure Bomb Measurements to Estimate Root Water Potentials1
Authors: Gee G. W. , Liu W. , Olvang H. , Janes B. E.
Published: July 2010

Pressure bomb measurements were used to estimate root water potentials of soil‐grown pepper (Capsicum annum L. cv. ‘California Wonder’) plants. Bomb measurements taken on roots of wilted pepper plants in dry soil overestimated the water potential by as much as 8 bars when roots were known to be damaged. When plants were equilibrated at low water potentials (‐10 to ‐14 bars) and the roots were undisturbed, differences between water potentials in the plant roots and top were 0.4 bars or less.

Increases in water potential with time were observed in both stressed and well‐watered plants where roots were not damaged but where there was no attempt to equilibrate the water potential gradient. Root resistance, root pressure and unsaturated conductivity of the soil all influence the tune dependence of root water potential.
Magnesium Concentration in Agropyron desertorum Fertilized with Mg and N1
Authors: Mayland H. F. , Grunes D. L.
Published: July 2010

Grass tetany, a Mg deficiency in ruminants, is responsible for large economic losses throughout temperate regions. Significant livestock losses occur in the semiarid western United States primarily when livestock are grazing the spring growth of Agropyron desertorum, an introduced grass species which provides much needed early spring forage.

The objective of this study was to increase forage Mg to about 0.2% by Mg and N fertilization and thus meet animal needs and reduce losses from death. The field study was located on A. desertorum grassland which had previously produced grass tetany. Two calcareous aridisols were each fertilized with 0, 90, 200, and 600 kg Mp/ha as MgS04·7H2O, having split plots with 0 and 150 kg N/ha applied as NH4NO3. Forage was harvested at regular periods intended to bracket the spring occurrence of tetany for three seasons following fertilization.

Fertilization with 600 kg Mg/ha was necessary to increase forage Mg to the recommended level (0.2%). Applying 150 kg N/ha increased forage Mg concentration as much as did 200 kg Mg/ha. The N and Mg fertilizers were additive in increasing forage Mg concentrations. Forage Mg concentrations decreased with increasing age of vegetatively growing grass, and the benefits from fertilization were less with each successive season following fertilization. Little residual effect of 600 kg Mg/ha or 150 kg N/ha fertilization on plant Mg concentration would be expected after 5 years. Rapid decreases in water‐soluble soil Mg with the resulting formation of some unknown insoluble phase, as well as high investment costs, preclude Mg fertilization of these ranges to meet Mg requirements of grazing animals.
Determining Moisture in Forages by Neutron Moderation1
Authors: Vanderlip R. L. , Owensby C. E. , Ball J. D.
Published: July 2010

A rapid, accurate method of determining forage moisture content would greatly facilitate forage research. Use of neutron moderation to determine moisture content of forages was studied using samples of corn (Zea mays L.), sorghum (Sorghum bicolor (L.) Moench.), bromegrass (Bromus inermis Leyss.), and alfalfa (Medicago sativa L.) containing a wide range of moisture contents to obtain a calibration curve for relating counts per minute to amount of moisture in the forage. A single calibration curve could be used for all four species.
Effect of Lime, Inoculant, and Molybdenum Pelleting of Seed on Growth and Nitrogen Content of Crownvetch1
Authors: Sims J. L. , Sigafus Roy E. , Tiaranan Noi
Published: July 2010

There is a growing interest in the use of crownvetch (Coronilla varia L.) for hay or pasture. Crownvetch has been widely used on highway banks, but there have been problems with getting good stands. The present study was conducted to evaluate the influence of pelleting seed with lime, molybdenum, and inoculum on germination, growth, and N content of crownvetch.

Gum arabic was used to secure materials to ‘Penngift’ crownvetch seed. A Culleoka silt loam soil with pH 5.0 and Grigg extractable Mo content of 0.56 kg/ha was used in greenhouse studies. Results showed that inoculant and Mo increased dry weight and N content of both tops and roots of crownvetch. Sodium molybdate at 70 g/ha was equally effective when pelleted to the seed or mixed uniformily with the soil. Neither pelleting nor uniform mixing of lime at the rate of 1.4 kg/ha influenced dry weights or N contents of roots or shoots in this soil, but uniform mixing of lime at the rate of 420 kg/ha significantly increased root weight. There was no significant treatment effect on germination but lime tended to reduce germination.

Numbers of surviving rhizobia in laboratory tests varied with storage time and treatment. By three days after wetting with water and gum arabic many rhizobia had died. Greatest reductions in numbers occurred when sodium molybdate was present except when the inoculum was attached to the seed first and separated from the Mo by a layer of lime. Only small losses of rhizobia occurred from the third to the ninth day of storage.
Measurement of Dark Respiration, Evaporation, and Photosynthesis in Field Plots1
Authors: Peters D. B. , Clough B. F. , Garves R. A. , Stahl G. R.
Published: July 2010

Present techniques for measurement of respiration, evaporation, and photosynthesis do not permit evaluation of a large number of experimental variables. A field plot technique is described which enables precise measurement from a large number of plots. A device is used that produces a closed canopy over a field plot for a short time during which CO2 and H2O concentrations are measured. The procedure produces minimal disturbance of natural field conditions and can measure CO2 and H2O fluxes with high precision.
Effect of Fertilizer and Plant Population on Yield of Soybeans1
Authors: Fink R. J. , Posler G. L. , Thorup R. M.
Published: July 2010

The combined effects of fertilizer and plant population on the yield of soybeans (Glycine max (L.) Merr.) have not been defined clearly, because in practically all related studies, each has been investigated independently of the other. The present study was conducted to measure these combined effects on ‘Calland’ soybeans. Soybeans received 336 kg/ha N, 155 kg/ha P, and 279 kg/ha K in 1971, but no fertilizer applied in 1972. Plant populations were 100,000 plants/ha grown in 76‐cm rows both years, and 400,000 plants/ha grown in 76‐cm rows in 1971 and both 38‐ and 76‐cm rows in 1972.

A significant yield response to directly applied fertilizer was obtained at a plant population of 400,000 in 1971, but not at 100,000. In 1972 the carry‐over fertilizer produced a significant yield response at 400,000 plant population in 38‐cm rows, but not in 76‐cm rows. However, there was a significant response (P = .10) at 100,000 plants/ha in 76‐cm rows. No significant yield differences were found among plant populations either year. The 38‐cm row spacing yielded significantly more than the 76‐cm row spacing at the 400,000 plant population where fertilizer was applied, but row spacing had no effect on yield of unfertilized soybeans.

It was concluded that, although inconsistencies do occur, fertilizer can contribute significantly to higher soybean yields whether applied directly or utilized as a carry‐over from a previous crop, and that plant populations as low as 100,000 plants/ha can produce yields equal to those produced by a higher population (400,000 plants/ha) under both fertilized and unfertilized conditions.
Line Source Carbon Dioxide Release. I. Field Experiment1
Authors: Allen L. H. , Desjardins R. L. , Lemon E. R.
Published: July 2010

Carbon dioxide gas was released from one northeastsouthwest line in a corn (Zea mays L.) field during several days in August and September, 1969. CO2 concentration profiles were measured at 15 and 45 m downwind. The purposes of the releases were: (1) to study the micrometeorological transport processes in plant canopies using CO2, as a tracer, and (2) to determine the micrometeorological feasibility of CO2 enrichment under field conditions. The study showed that vertical turbulent diffusion and horizontal mass flow quickly diminished the concentration of CO2, downwind from the line source. High concentrations of CO2 could be maintained in the canopy only under a stable temperature stratification of the air which reduced vertical wind fluctuations. Short‐term eddies with CO2 concentrations in excess of 1,000 ppm were observed 30 m downwind from the release line at an analyzer height of 530 cm, but these were very infrequent. CO2 concentration profiles showed that CO2 tended to be turbulently diffused upward and wafted downwind, with some of the CO2 being again transported into the canopy. Turbulent diffusion in the canopy was usually too active to maintain a high CO2 concentration; however, this same effectiveness of turbulence assures an adequate supply of CO2 to plant canopies under typical field conditions. This study showed, from a micrometeorological viewpoint, that CO2 enrichment would not be practical under most natural field and crop conditions because of rapid gaseous exchange with the bulk atmosphere.
Application of Long‐Arc Xenon Lighting for Plant Growth Experiments1
Authors: Jarman G. D. , Barlow E. W. R. , Boersma L.
Published: July 2010

The installation and use of a 2,500‐W xenon long‐arc lamp is described. Xenon arc lamps emit a high intensity radiant flux with a visible spectrum similar to that of unfiltered sunlight. These qualities make it desirable for use in laboratory studies of plant growth. Little published information describing the use of xenon lamps in such application is available. Many technical problems may be encountered in the installation of long‐arc xenon lamps because of the lack of adequate installation instructions. The information presented here was developed over a long period of time and particular emphasis is on safety and cooling requirements.

Although this lamp is expensive to install and operate, the spectral distribution of its radiation within the visible (400 to 700 nm) and near infrared wavebands is closer to that of natural sunlight than any other lamp presently available. Within the photosynthetically active waveband the conversion factor from radiant to quantum flux was determined to be 4.56 μ Einstein s−1 m−2 per Wm−2 [Wm−2 = Watts per m,2. Diagrams were prepared showing the angular distribution of radiation from this lamp.
Goosegrass Control in Bermudagrass Turf with Combinations of MSMA and S‐Triazines1
Authors: Murdoch C. L. , Ikeda David
Published: July 2010

Annual weed control in turf is difficult in tropical and subtropical regions because of year‐long growing seasons. Preemergence herbicides are ineffective because all growth stages are present and seed germination occurs throughout the year. Postemergence herbicides may control existing weeds, but they are soon replaced by germinating seeds.

We conducted field and greenhouse experiments to evaluate the effectiveness of combinations of monosodium methane arsonate (MSMA) and s‐triazine herbicides for controlling goosegrass (Eleusine indica L.) in Hawaii. Excellent goosegrass control was obtained when s‐triazine herbicides were used, followed by two or three applications of MSMA. Three applications of MSMA alone was ineffective in controlling mature goosegrass. No phytotoxicity was observed from any herbicide treatment on common bermudagrass (Cynodon dactylon L.) ‘Tifgreen’ bermudagrass (Cynodon dactylon ✕ C. transvaalensis Burt‐Davy) was discolored by all herbicide treatments; however, the injury was of short duration.

The increased control of goosegrass with combinations of MSMA and s.trlazines was attributed to increased herbicidal activity of the combinations as compared to that of either herbicide alone and to the long residual preemergence activity of s‐triazlnes which prevented reinfestation in the field experiment.
Chemical Factors Controlling the Adaptation of Weeping Lovegrass and Tall Fescue to Acid Mine Spoils1
Authors: Fleming A. L. , Schwartz J. W. , Foy C. D.
Published: July 2010

Successful revegetation of acid mine spoils can be facilitated by the use of plant species which can tolerate the existing growth‐limiting conditions. Although species differences can be determined by growth on the particular spoil, specific knowledge of the plant response to each of the potential stresses will increase the reliability of the selection process.

The objectives of this study were to evaluate the response of weeping lovegrass [Eragrostis curvula (Schrad.) Nees] and tall fescue (Festuca arundicea Schref. var. ‘Ky 31’), to Al, Mn, and other major growth‐limiting factors which may be encountered in acid strip mine spoils and to specify which factors would account for the observed differences between these species.

Weeping lovegrass and tall fescue were grown for 26 to 31 days in nutrient solution culture containing Al, Mn, and P as variables. Each experiment in the series was designed to compare the response of the two species to a specific growth‐limiting condition.

Although both species withstood low pH (pH 4 to 5) and excess Mn (4 to 64 ppm), weeping lovegrass was more tolerant than tall fescue to A1 concentrations in the range 2 to 12 ppm. A concentration of 4 ppm Al severely inhibited the top and root devdopment of tall fescue, but 12 ppm AI was required to produce similar injury to weeping lovegrass.

The application of 2 to 4 ppm P promoted the growth of both species without Al and decreased, but did not overcome the effect of 4 ppm Al on tall fescue. Higher P treatments (6 ppm), in the presence of 4 ppm A1, increased the top growth of tall fescue, with little effect on the root system. The response of weeping lovegrass to P was not altered by the presence of Al.

Weeping lovegrass should be favored for revegetation of acid mine spoils of low pH which are high in exchangeable Al. Both weeping lovegrass and tall fescue could be grown on spoils dominated by Mn.
Growth of Kikuyugrass (Pennisetum clandestinum) Under Clipping. II. Regrowth Characteristics in Relation to Nitrogen Fertilization and Climate1
Authors: Whitney A. S.
Published: July 2010

A better understanding of the response of kikuyugrass (Pennisetum clandestinum Hochst. ex Chiov.) to management and climate is needed in order to best exploit this important forage grass. The objective of this study was to describe kikuyugrass regrowth under a variety of conditions and to relate regrowth performance to N‐nutrition, environment, and sward characteristics. Kikuyugrass swards at two locations (Kula, 945 m elevation, and Makawao, 660 m elevation) were trimmed and fertilized with three levels of N (22, 56, and 168 kg/ha) at 10‐week intervals. During alternate 10‐week periods, plots were cut sequentially after 4, 6, 8, and 10 weeks of regrowth. Regrowth began slowly after a 10‐week period, especially at Kula during the cool season. Changes in the area: dry weight ratio of the forage indicated that this may have been due to retarded leaf development under low temperatures. At other times, regrowth at both locations was normally rapid after the 4th week and continued at a high rate through the 10th week. About 600 kg/ha of harvestable green vegetation (DM basis) were required support subsequent near‐maximum growth rates. This was equivalent to 8 cm harvestable height, 30% interception of blue light, and a leaf‐plus‐stem area index of 1.0.

Crude protein (CP) yields tended to level off after weeks, especially during the warmer months. Percent CP in the low and moderate N treatments declined during the regrowth period from approximately 16 to 18% at 4 weeks to 8% at 10 weeks. Percent CP in the high‐N treatment was higher but more seasonally variable; 4‐week regrowth contained over 30% CP equiv. during the cooler months. Some of this N was present as NO3 which ranged from 20 ppm NO3‐N (low or moderate N‐level, 8 weeks regrowth) to over 2000 ppm (high N‐level, 2 to 6 weeks growth at Makawao). Nitrate levels thus approached potentially toxic concentrations for ruminants in some cases.

Multiple regression analysis identified several factors as being significantly associated with growth rate: nitrogen nutrition of the sward, temperature (air or soil), and position on the growth curve. Unidentified site factors were also determinants.
Influence of Cutting Management and Environmental Variation on the Yield, Bud Activity, and Autumn Carbohydrate Reserve Levels of Crownvetch1
Authors: Brann D. E. , Jung G. A.
Published: July 2010

‘Chaining’ crownvetch (Coronilla varia L.) was grown at four West Virginia locations: Morgantown, Wardensville, Reedsville, and Point Pleasant. These locations vary in amount and distribution of rainfall, temperature, snow cover, and length of growing season and show how combinations of environmental factors affect yield, morphology, and carbohydrate reserves. Yield and bud activity as affected by cutting at different growth stages and heights are presented. The effect of two and three harvests per season on yield and fall carbohydrate levels was also studied.

Yields varied greatly among locations and years. Greater than 10,000 kg/ha were produced at Morgantown in 1969 and Reedsville in 1970 compared with total yields at Point Pleasant of 2,000 to 4,000 kg/ha from a thin stand. Greater yields generally were produced by two rather than three harvests per season. Clipping to stubble heights of 7.5 or 15.0 cm resulted in similar yields. First cutting yields generally increased as the first harvest was delayed to full bloom (mid‐June); however, delaying harvest past this period seldom increased yield. Cutting treatments did not detrimentally affect any of the stands, except possibly at Morgantown, where general vigor of the stand was lower the second season.

The proportion of axillary buds producing growth increased with delay of spring harvest until full bloom and then declined. Delay of the first cutting and adequate moisture increased the proportion of axillary buds that produced regrowth. Cutting at different stubble heights generally had no effect on activation of axillary buds.

Initiation of growth from crown buds was determined 2 weeks after cutting. Active buds at the crown and up to 2.5 cm from the base of 100 randomly selected stems were counted. Growth initiation from crown buds was greater when plots were cut at 7.5 cm than when cut at 15.0 cm for most cutting dates and locations. Crown bud activity was generally less during early spring and periods of moisture stress.

Total non‐structural carbohydrates (TNC) in autumn were similar among locations. Slightly higher TNC values were associated with the 15.0 cm cutting heights, due mainly to changes in starch levels.
Ameliorative Role of Zinc on Maize Growth Under Alkali Soil Condition1
Authors: Shukla U. C. , Prasad K. G.
Published: July 2010

While working with some of the Natrargids it was observed that zinc had beneficial effects on the germination and growth of plants. To verify this observation, a greenhouse experiment was conducted. Zinc application enhanced germination percentage, plant growth, Zn, and K concentration and K/Na ratio in maize (Zea mays L.) whereas Na concentration and P/Zn ratio decreased. Application of S alone increased Na and S concentrations, decreased K and Ca concentrations and K/Na ratio. Except for Zn and K, the concentrations of other nutrients studied were higher in plants receiving S than those receiving Zn or Zn + S treatments. The ameliorative role of Zn in plant growth under alkali soil conditions was found to be associated with the changes brought about in the chemical composition of plants.
Competition and Plot‐Dimension Effects in Yield Tests of Safflower Cultivars1
Authors: Abel G. H.
Published: July 2010

Information is needed on the competition effects of safflower, Carthamus tinctorius L., in yield trials of small plots. Six cultivars differing in growth rate and height were planted adjacent to one another in different plot sizes and shapes.

In two‐row plots, differences in height in mid‐April (mid‐branching) were not related to yield of straw or seed. Adjacent plot differences of 18 cm in plant height at maturity did not affect straw yield, and differences of 25 cm did not affect seed yield. With adjacent plot differences of 41 to 59 cm, the taller cultivars produced more straw and the shorter cultivar produced less straw and seed than when grown in solid stand. Seed yield was more affected by competition than straw yield.

Increasing the area of the plot from 1.4 to 5.8 m2 decreased variation. Plots of parallel basic units were more highly correlated for yield of straw and seed than end‐to‐end units.
Fertilizer Studies with Groundnuts on the Brown Sands of Guyana. II. Effect of Nitrogen, Phosphorus, Potassium, and Gypsum and Timing of Phosphorus Application1
Authors: Chesney H. A. D.
Published: July 2010

The effects of N, P, K, and gypsum and timing of application of P on the performance of groundnuts (Arachis hypogoea L.), grown on the Brown Sands of Guyana, were studied. Generally, 15 kg N/ha gave optimum production. However, in a dry season on the coarser textured soils and during all seasons on a finer textured soil 32 and 48 kg/ha of N were needed, respectively. Application of up to 30 kg P/ha increased yields on all soils found under savannah vegetation except the finest textured one. P did not increase yields of groundnut on the soil occurring under forest vegetation. Potassium within the range tested (124‐164 kg/ha) had no effect on yield. Application of up to 495 kg gypsum/ha increased yield and reduced the number of “pops.” Application of all the P at planting produced higher yields than when the application was split, and this effect was greater during periods of stress and at low rates of gypsum. Timing of P applications had no effect on the number of “pops.”

Both P and K increased in all four soils with repeated applications of the respective fertilizers. The amounts accumulated however, were small relative to the quantities applied. Potassium accumulation increased with the clay content of the soils. Total N increased in two soils only.
Manganese Supply, Growth, and Micronutrient Concentration in Grain Sorghum1
Authors: Ohki K.
Published: July 2010

Reference values for manganese related to plant growth are needed for the assessment of Mn status and micronutrient relationships associated with Mn in grain sorghum (Sorghum bicolor [L.] Moench.). Sorghum was grown to boot stage in nutrient solution with eight Mn levels from 0 to 4,000 µg Mn/liter under greenhouse conditions. Sorghum growth and Mn concentrations in vegetative tissues were dependent on Mn supply in nutrient solution. Mn concentrations of blades 1 (flag‐leaf) through 5 in basipetal order were related to plant growth but blade 1 was the most sensitive tissue in relating Mn concentration to plant growth. The critical Mn levels for blades 1, 2, and 3 were 10, 10, and 15 ppm, respectively, while critical levels for blades 4 and 5 were 32 and 60 ppm, respectively. Blade 1 is suggested as the leaf to sample at boot stage for evaluating the Mn status of the plant. Zinc concentration in blade tissue increased at Mn concentrations below the critical Mn level. Copper concentration remained relatively constant within a wide range of Mn concentration and Fe concentration decreased at low Mn supply levels.
Seed and Oil Quality of Flax After Swathing1
Authors: Dorrell D. G. , Hodgins M. W.
Published: July 2010

Seed flax (Linum usitatissimum L.) is frequently cut before fully ripe and left to mature in the swath to hasten or overcome uneven maturity. To determine how swathing effects seed yield as well as seed and oil quality, oilseed flax cultivars were planted at different times in 2 years; then swathed at three stages of seed development ranging from the start of ripening to fully ripe. Swathed plots were sampled during the course of drying and compared with plants left standing. Measurements were taken on capsule moisture, seed weight, yield, color, germination, and oil content as well as fatty acid composition and iodine number of the oil. If swathing took place when the majority of the capsules contained approximately 35% moisture, subsequent drying in the swath produced seeds of excellent quality. Seed weight and total seed yield from swathed plots were slightly reduced; fatty acid composition of the oil was essentially unaffected; and seed color, seed germination, and oil content were slightly higher when compared to flax plants left standing to mature normally. Plants could be swathed when capsules contained as much as 50% moisture and still produce a high quality oil; however, seed germination, seed color, and yield were significantly reduced.