bluuebunny/crossref_metadata_2025 huggingface dataset:
Variety and Row Spacing Effects on Recoverability of Soybeans from Simulated Hail Injury1
Authors: Burmood D. T. , Fehr W. R.
Published: July 2010

Two soybean [Glycine max (L.) Merr.] cultivars were grown in 100‐ and 50‐cm rows to evaluate the influence of cultivar and row spacing on recoverability from hail injury. ‘Hawkeye’ and ‘Hark’ soybeans were treated at three stages of plant development with 0, 25, and 50% stand reduction and 0, 25, and 50% stem cut‐off at ½ height.

The experiment was conducted at Ames, Iowa for 3 consecutive years. The percentage yield loss averaged across years and treatments was the same (7%) for both row spacings of Hark and only 1 percentage point different (3% for 100‐cm and 4% for 50‐cm rows) for Hawkeye. No significant row spacings ✕treatments or row spacings ✕treatments ✕cultivars interactions were observed. Row spacing does not appear to warrant consideration in adjustment of soybeans for recoverability from hail injury.

Average yield loss for Hark (7.0%) was more than for Hawkeye (3.5%) when averaged across years, treatments, and row spacings. The cultivars ✕stem cut‐offs interaction was not significant, but the cultivars ✕stand reductions interaction was significant at the 1% probability level. Hark had greater yield loss due to stand reduction than Hawkeye, primarily at the 50% level of stand reduction. Although small differences for recoverability did occur between cultivars, the differences were not great enough to justify the evaluation of all commercial soybean cultivars for their recovery potential. Such an evaluation would be necessary if cultivar is to be considered in the adjustment of hail losses.
Response of Three Corn Hybrids to Low Levels of Soil Moisture Tension in the Plow Layer1
Authors: Rhoads F. M. , Stanley R. L.
Published: July 2010

Fertilizer materials are generally mixed with the soil to plow depth and as a result, concentration of corn (Zea mays L.) roots is usually greatest in the surface soil; therefore, water demand is expected to be highest in the plow layer.

The objective of these experiments was to evaluate the response of three corn hybrids to irrigation treatments that were designed to maintain soil moisture tension at low levels (less than 1‐bar) in the plow layer rather than the entire root zone. Flowering date, plant height, and grain yield were used as indexes of response.

Irrigation was applied at four levels (0.3, 0.6, 2.0, and 5.0 bars) of soil moisture tension in 1970 and at three levels (0.2, 0.4, and 0.6 bar) in 1971. Nitrogen was applied at 336 and 560 kg/ha, in 1971, to treatments irrigated at 0.2 bar of soil moisture tension. Each irrigation treatment was replicated four times and consisted of applying water at a selected value of soil moisture tension. A tensiometer was placed in each plot to in irrigated at soil moisture tensions below 1 bar in order to monitor soil moisture tension at a depth of 15 cm. Electrical resistance units were used in 1970 to monitor soil moisture tension in plots irrigated at tensions above 1 bar.

Flowering occurred earlier and plant height increased as soil moisture tension at irrigation decreased. Grain yields were increased significantly (5% level) each year when plots were irrigated at 0.2 or 0.3 bar soil moisture tension instead of 0.6 bar. Irrigation at 0.6 bar did not increase grain yields in comparison with no irrigation in 1970. Each corn variety gave an inverse linear grain yield response to soil moisture tension values between 0.2 and 0.6 bar in 1971. There was a significant difference (5% level) between varieties in magnitude of grain yield response to irrigation in 1971. Highest grain yields were produced each year when soil moisture tension in the plow layer was maintained below 1/3 bar.
Influence of Cultivar, Row Spacing, and Number of Rows on Yield of Wheat Plots1
Authors: Rich Pat A.
Published: July 2010

Cultivar competition in wheat (Triticum aestivum L.) yield plots has been acknowledged for more than 50 years. However, measurements of the effects of possible interactions of cultivars and row spacings in two‐, four‐, and six‐row plots have not been investigated together in planned experiments. The objective of this study was to study the influence of two‐, four‐, and six‐row plots with 15‐, 20‐, 25‐, 30‐cm row spacings on the yield of a normal height wheat (‘Riley 67’) and a semi‐dwarf wheat (‘Sturdy’) in 4 ✕ 3 ✕ 2 factorial experiments. Marked cultivar ✕ rows per plot interactions indicated cultivar competition. The yield of Sturdy was linear function of rows per plot but the yield of Riley 67 was an inverse linear function. Sturdy plot yields were (i) larger than Riley 67's in six‐row plots, (ii) not different from Riley 67's in four‐row plots, and (iii) less than Riley 67's in two‐row plots. The data indicate that six‐row plots with 15‐, 20‐, 25‐, or 30‐cm row spacings are needed for valid yield evaluation in perennial experiments, but in annual experiments six‐row plots with 30‐cm row spacing should be used.
Effect of Cutting Date on Digestibility and Intake of Irrigated First‐Crop Alfalfa Hay1
Authors: Anderson M. J. , Fries G. F. , Kopland D. V. , Waldo D. R.
Published: July 2010

Delayed cutting during the practical harvesting season of first‐growth forages raised in humid climates has resulted in a linear decline in the digestibility component of nutritive value. This study considered the effect of cutting date upon the digestibility and intake components of nutritive value of first growth alfalfa (Medicago sativa L.) raised under irrigated conditions at two altitudes in Utah and Montana. Duration of the study was 5 years with harvests occurring over ranges of 23 to 62 days. Intake and digestibility by total collection of each hay were determined with four sheep. Digestibility was determined during three years at both ad libitum and a controlled feeding level. Hays were harvested at Huntley, Montana for the first two years and at Logan, Utah for the remaining three years. The variety ‘Ranger’ was used during the first four years and ‘DuPuits’ and ‘Lahontan’ varieties were compared during the last year. Daily intake of dry matter decreased 0.21 g/kg BW¾ for each day of delay with large variations in rate of change for different year‐variety sets of data. Digestibility of the dry matter decreased approximately 0.28 percentage units per day for both Huntley and Logan hays, but Ranger alfalfa was about six percentage units more digestible on June 10 at Huntley than at Logan. Correlations between dry matter and energy digestibilities and between dry matter and organic matter digestibilities were 0.98 and 0.97, respectively. Crude protein concentration declined 0.20 percentage units per day. Digestible protein concentration of alfalfa forage can be expressed as a function of crude protein concentration by Y = −4.15 + 0.97X with r = 0.98.
Movement of Herbicides through Soil to Soybean Roots1
Authors: Don Scott H. , Phillips Ronald E.
Published: July 2010

Absorption of pesticides is one of the primary means by which pesticide residues enter the food chains of humans, domestic animals, and wildlife. Thus, a comparison was made between the theoretical and observed uptake of isopropyl m‐chlorocarbanilate (chlorpropham) and 2‐chloro‐4‐( ethylamino )‐6‐ (isopropylamino)‐s‐triazine (atrazine) from soil by soybean roots (Glycine max (L.)). The rate of absorption of both 14C‐herbicides as determined by liquid scintillation techniques was rapid initially and decreased as plant growth increased. These rate curves were approximately parallel throughout the growth range with the rate of absorption of atrazine being always greater than that of chlorpropham.

The theoretical movement of the two herbicides to the root surface was calculated assuming certain boundary conditions for the system. Assuming the roots to be “perfect sinks,” the diffusion process accounted for the total quantity of herbicide absorbed except during the early hours following germination. As root growth increased, the roots became less of a sink for these two herbicides, and diffusion to a “perfect sink” could theoretically supply more than the amount absorbed. Assuming the rate of uptake to be proportional to the concentration at the root surface, a curvilinear rate constant was observed during the uptake period. The data indicated that the plant controlled the amount of herbicide accumulated as well as its principal transport mechanism to the root, probably through its influence on the permeability of the root or root saturation.
Effects of Gibberellic Acid and Sublethal Levels of Four Herbicides on the Cool‐season Regrowth of Two Tropical Forage Grasses1
Authors: Whitney A. S. , Green R. E. , Younge O. R.
Published: July 2010

A series of experiments were conducted at two locations in Hawaii to evaluate the feasibility of increasing the cool‐season growth of pasture grasses by means of chemical sprays.

In a preliminary trial from December to March, pangolagrass (Digitaria decumbens Stent) was treated with three levels of nitrogen (0, 56, and 112 kg/ha as (NH4)2SO4) and then with the following chemicals: ametryne, atrazine, simazine, and dicamba, each at 560 and 2240 g/ha; and gibberellic acid (GA) at 12 and 37 g/ha. Ametryne at 2240 g/ha reduced yields at the ll2‐kg N/ha level only. No other significant effects were noted, but there was some indication of a small non‐significant GA response.

Kikiyugrass (Pennisetum clandestinum Hocht. ex Chiov.) was treated at two locations during February with three levels of N (22, 56, and 168 kg/ha as (NH4)2SO4) and then with simazine at 247 or 741 g/ha, GA at 62 g/ha, or simazine plus GA. Simazine did not affect yields except at the 168‐kg/ha level of N at the 640‐m elevation site; under this set of conditions, dry matter (DM) and crude protein (CP) yields were increased by 40% over the untreated control.

Much larger increases in DM and CP yields were associated with GA treatment; relative increases were highest, up to 9‐fold, under low N levels, especially at the 900 m elevation site (av. soil temp. @ 5 cm ≤ 18 C). Absolute responses were highest, up to 2200 kg DM/ha, under high nitrogen levels and at the 640 m elevation. The GA treatment appeared to stimulate production by causing rapid increases in both photosynthetic area and stem tissue. The added stem tissue presumably provided additional carbohydrate “sink” capacity, thereby minimizing starch accumulation in the chloroplasts during daylight hours. Subsequent yields of GA‐treated swards harvested a second time were less than controls at the 900 m elevation but greater than the controls at the 640 m elevation.

The limited response from the application of triazine compounds is in contrast to many previous reports. Our results indicate that they may be of only limited usefulness for tropical grasses, especially when the N is supplied in forms other than nitrate.

In contrast, the application of 62 g/ha of GA may be a useful adjunct to nitrogen fertilization for increasing forage production during periods of moderate temperature stress.
Water Loss from an Irrigated Sorghum Field: II. Evapotranspiration and Root Extraction1
Authors: Stone L. R. , Horton M. L. , Olson T. C.
Published: July 2010

Techniques for estimating evapotranspiration from water depletion within the soil profile frequently do not account for flux below the root zone. A method using tensiometers for obtaining evapotranspiration rates and root extraction patterns within an actively growing sorghum (Sorghum bicolor (L.) Moench) crop is discussed. Profile water depletion was calculated from water content profiles determined using tensiometer readings and laboratory‐measured soil water characteristics. Profile water depletion minus flux below the root zone yielded the daily evapotranspiration rate. During the 31‐day study, approximately 65% of the total water loss was due to evapotranspiration and approximately 35% was due to flux loss from the root zone. These data clearly show the importance of considering flux below the root zone when attempting to determine evapotranspiration rates using depletion methods. The method of determining evapotranspiration rates illustrated in this paper provides an alternative to the microclimatological and lysimeter methods.
Experimental Grassland Renovator1
Authors: Smith E. M. , Taylor T. H. , Casada J. H. , Templeton W. C.
Published: July 2010

Grassy swards inevitably become deficient in nitrogen unless some measure is used to replenish the supply. Renovation is a process by which legumes may be introduced into grass‐dominant fields. The legumes serve to replenish the nitrogen and to improve the quality and quantity of forage produced.

The main problems in grassland renovation have been to determine tillage and seed placement requirements and to develop methods to meet these needs. Basic research has shown that there is a high probability of success in establishing whlite clover (Trifolium repens) and alfalfa (Medicago sativa L.) in a Kentucky bluegrass (Poa pratensis L.) sod when the following tillage and seed placement requirements are satisfied: till a furrow 0.6 cm wide and 1.9 cm deep, place the seeds in this furrow, cover the seeds 0.6 to 1.2 cm deep, press the soil over the seeds, and spray a band of herbicide 10 cm wide over the seeded furrow.

The once‐over renovator described in this note is designed to satisfy the specified requirements of tilling, seeding, cnltipacking, and spraying. Tillage is accomplished with power‐driven blades that float in a vertical plane to follow the land surface, while seed placement is achieved with small double‐disk openers. The machine is designed to operate on rough terrain such as is prevalent in many grassland situations.
Reflectance, Transmittance, and Absorptance of Light by Subcellular Particles of Spinach (Spinacia oleracea L.) Leaves1
Authors: Gausman H. W.
Published: July 2010

This study considered the premise that subcellular particles in leaves contribute to the reflectance (R) and absorptance (A) of near‐infrared (IR) (light 750 to 350 nm).

Subcellular particles of spinach (Spinacia oleracea L.) leaves were differentially sedimented and resuspended in a buffered sucrose solution. A spectroreflectometer was used to measure R and transmittance (T) over the 500‐ to 2,500‐nm wavelength interval (WLI) on replicated aliquots of five preparations: buffered sucrose solution (control); chloroplast preparation; S1, sediment of chloroplast preparation supernatant; $2, sediment of S1 supernatant; and S3, sediment of S2 supernatant. Absorptance was calculated: A= 1 ‐ (R + T).

All suspensions of particulates caused less R than the buffered sucrose solution over the 500‐ to 650‐nm WLI. The chloroplast preparation, compared with the buffered sucrose solution, increased R over the 750‐ to 950‐nm WLI.

The chloroplast preparation, compared with the buffered sucrose solution, S2, and S3, decreased T over the 500‐ to 1,250‐nm WLI; SI decreased T over the 500‐ to 900‐ nm WLI.

Compared with remaining treatments, the chloroplast preparation increased A over the 500‐ to 1,100‐nm WLI.

Excluding the buffered sucrose solution, R and A increased and T decreased in the IR region as particle size increased.

A conclusion was reached that subcellular particles in leaves contribute to the R and A of IR light.
Diurnal Variation in Nonstructural Carbohydrates of Sorghum sudanense (Stapf) as Influenced by Environment1
Authors: Lechtenberg V. L. , Holt D. A. , Youngberg H. W.
Published: July 2010

Sudangrass (Sorghum sudanense (Stapf) herbage (leaves plus stems) and leaves, with 0 and 140 kg/ha of N fertilizer, were sampled four times daily on 8 days and eight times daily on 3 days to i) measure the diurnal variation in several nonstructural carbohydrates, ii) relate carbohydrate trends to environmental conditions, and iii) determine the influence of nitrogen fertilization on diurnal carbohydrate changes.

Reducing sugars and sucrose were extracted from freeze‐dried, ground tissue with alcohol. Starch in the residue was hydrolyzed with takadiastase. Ferricyanide, resorcinol, and phenol‐sulfuric acid procedures were used to quantitatively assay sugars in the extracts.

Sucrose concentration in sudangrass herbage varied from 1.8% of the dry matter at 6 AM to 5.8% at 6 PM. Starch increased from 6.6 to 8.8% in the same period. Half of the daily increase in carbohydrate disappeared between 6 PM and 12 M. The diurnal trends in leaves were similar to those observed in herbage. Nitrogen fertilization (140 kg/ha) reduced the average total carbohydrate concentrations from 16.6 to 14.8% but did not change the magnitude of diurnal trends. Starch concentration declined from 9.9 to 5.9% of the dry herbage and sucrose increased from 1.2 to 6.6% during the 16‐day sampling period. This change was more pronounced in N‐deficient sudangrass. Rates of sucrose accumulation varied with radiation level and temperature, but the maximum concentrations reached each day were about 5.5%, indicating a physiological limit. A cold night caused the leaves to retain unusually high levels of sucrose overnight. Sucrose concentrations were as high as 2.5% compared to concentrations of less than .3% on warm nights. Sudangrass temporarily stores most excess photosynthate as sucrose in contrast to alfalfa (Medicago sativa L). which accumulates much more starch.
In situ Estimation of Alfalfa Forage Yields1
Authors: Burzlaff D. F. , Ham G. L. , Kehr W. R.
Published: July 2010

An electronic capacitance meter to estimate yields of forage in situ was developed and tested at the University of Nebraska, Lincoln. Use of this type of measurement leaves vegetation in a relatively undisturbed state with a potential for successive sampling at the same location. The forage meter permits estimation of growth rates over short periods of time as well as forage consumption under grazing. Prediction equations were developed for use of the machine in estimating first‐ and second‐cutting alfalfa (Medicago sativa L.) yields. Yield predictions of alfalfa varieties were obtained with the capacitance meter and compared to data obtained by conventional harvest procedures. The results indicated that yields of first‐ or second‐cutting alfalfa can be estimated by use of an electronic capacitance meter. Correlation coefficients (r) of .80 for first‐cutting and .73 for second‐cutting were obtained for estimating alfalfa yield in situ as compared to conventional harvesting procedures.
Response of Subirrigated Hay Meadows to the Application of Nitrogen, Phosphorus, and Sulfur1
Authors: Rehm G. W. , Moline W. J. , Sorensen R. C. , Burzlaff D. F.
Published: July 2010

Hay production from subirrigated meadows is an important part of the economy of several states. Although fertilization with N and P had been researched in separate studies, little attention had been directed toward the interaction effect of these nutrients on forage production and the grass‐legume composition of these meadows. This study was designed to evaluate the effect of five rates of N, P and S on the yield and grass‐legume composition of subirrigated meadows. Forage yields were recorded and separations made to determine grass‐legume composition. Yields increased linearly with applied N while the response to P was curvilinear. There was no response to S. The percentage of grass in the meadows increased with applied N. Legume percentages increased with added P. Grass yields showed a linear increase with applied N and a curvilinear response to added P. Legume yields decreased linearly at low P rates when high rates of N were applied but increased curvilinearly as P rates were increased. Throughout the study, combinations of N and P produced the highest yields, thus demonstrating the importance of the combination of these two nutrients for maximum production from subirrigated hay meadows.
Plant Water Status in Relation to Clouds1
Authors: Stansell J. R. , Klepper Betty , Browning V. Douglas , Taylor H. M.
Published: July 2010

Clouds can cause significant changes in plant water status in a short time. Therefore, care should be taken to sample different treatments under comparable radiation.
Muskmelon Response to Rates and Sources of Nitrogen1
Authors: Wilcox Gerald E.
Published: July 2010

The method and rate of nitrogen fertilization of muskmelons (Cucumis melo) on sandy soils is of concern because of the leaching potential of N. The relative availability of nitrogen from ammonium nitrate, urea‐formaldehyde, and sulfur coated urea (SCU) was studied in the field with regard to influence on growth, leaf and petiole composition, and fruit yield of muskmelon. The field studies compared various nitrogen materials in different timing and rate schedules. The fertilizers were used at 0, 33, 66, 99, 132, and 264 kg/ha in single (preplant) and split (preplant + sidedressing) applications. Data were collected for 4 seasons. In each year N application increased vine growth and intensity of the green color of the leaves. The N concentration of the recently mature melon leaves was increased more by NH4NO3 than by urea‐formaldehyde or SCU. The relationship of N rate was linear with N composition but parabolic with yield. Optimum plant growth and fruit yields were obtained with a preplant application of 80 to 90 kg/ha. The same total N rate as a split application or as a less available N source was not as effective for fruit yield production. The increased yield from N treatment was due to increased vine size and increased numbers of fruit. Optimum fruit yields were produced at leaf composition of total N over 4.5% or petiole content of NO3‐N over 15,000 ppm during vegetative and fruit initiation stages. Sulfur coated urea with 37% dissolution rate produced NO3‐N and total N concentrations of petioles about equal to the same N rate as NH4NO3; SCU with 12% dissolution rate resulted in NO3 concentrations equal to one‐quarter the N rate as NH4NO3 at the runner stage and equal to one‐half the N rate as NH4NO3 just prior to harvest.

Ammonium nitrate, a soluble, immediately available N source, applied in preplant at 80 to 90 kg/ha was the most effective treatment and resulted in optimum muskmelon fruit yields on sandy soils of southwestern Indiana in each year of the study.
Influence of Previous Crop on Nitrate Distribution in a Clay Soil Profile and Subsequent Response to Applied N1
Authors: Hipp Billy W. , Gerard C. J.
Published: July 2010

Crop response to N can be difficult to predict under semitropical irrigated conditions. To aid in the explanation of erratice N response, studies were conducted over a 4‐year period to determine the influence of cotton (Gossipium hirsutum L.) and sorghum (Sorghum bicolor (L.) Moench.) on NO3‐N distribution in a clay soil profile and its effect on subsequent crop response to applied N. Double‐cropping systems used in the study were cotton— winter vegetable and sorghum—winter vegetable with plots split to include N rates of 0, 67, and 134 kg/ha. Nitrate nitrogen determinations were made periodically from soil samples taken from profiles of each treatment. Where sorghum was grown for 3 years, the profile was depleted of NO3‐N to a depth of 120 cm. In contrast, where cotton was grown NO3‐N accumulated at the 60 to 120 cm depth. This resulted in little response to residual N by mustard (Brassica juncea) after sorghum, but residual N from applications of 134 kg/ha per year to cotton precluded a response to N applied to winter mustard. These studies indicate that the depleted soil profile after sorghum results in a need for higher rates of N fertilizer on crops following sorghum than those following cotton.
Recovery of K2SO4 by Alfalfa After Placement at Different Depths in a Low Fertility Soil1
Authors: Peterson L. A. , Smith Dale
Published: July 2010

Knowledge of the quantitative contribution of plant nutrients from the soil volume penetrated by crop roots is needed for an overall analysis of present methods of fertilization. An experiment was initiated in 1971 to determine the uptake of K and SO4 by alfalfa (Medicago sativa L.) from different depths in a low K Plano silt loam soil profile. An injection method was used to place a solution of K2SO4 at depths of 7.5, 22.5, 37.5, 52.5, 67.5, and 82.5 cm below the soil surface in a 2‐year‐old stand. A check and surface broadcast application of K2SO4 also were included as treatments. Potassium sulfate was applied at the rate of 224 kg/ha of K and 92 kg/ha of S. Treatment areas were 8350 cm2. Three cuttings of the entire treatment area were made at first flower during the 1971 season, and the herbage was analyzed for yield and concentrations of K and S.

Alfalfa recovered 41, 29, 19, 16, 10, 15, and 11% of the added K from the surface, 7.5, 22.5, 37.5, 52.5, 67.5, and 82.5 cm soil depths, respectively. No major differences were observed in S concentration of the tissue between the check and treatments.

These data show that alfalfa absorbed K most heavily from the surface soil area as compared to the Ap and deeper horizons.
Influence of Tobacco Plant Canopy on Percolation1
Authors: Terry D. L.
Published: July 2010

This study was conducted to investigate the relationship between percolation at various positions in Lakeland sand and Norfolk loamy sand soils under tobacco (Nicotiana tabacum L.) culture and the growth and development of the plant canopy. A procedure is described for making direct measurements of percolation at various positions at a depth of 30 cm in a soil with respect to plant location as follows: A) through a ridge directly below a plant; B) through a ridge half way between two plants; C) through a fallow ridge; and D) through a fallow level area. During the first 15 to 20 days of the season percolation was similar at all positions studied and amounted to 40 to 60% of an average rainfall. From about 40 days after transplanting to the end of the growing season percolation at position A was about 40 to 100% of the rainfall while that at B and C was near zero. Percolation at D was intermediate averaging around onehalf that of A. The large amount of percolation at A after canopy development was explained as the result of water being intercepted by the leaves and channeled to the base of the stalk. The results indicated that percolation and possible leaching below 30 cm in a tobacco field are significant during the early part of the season (15 to 20 days from transplanting or later); however, after canopy development (40 to 49 days from transplanting or earlier) they are probably not significant except in a small soil volume directly below the plants.
Evaluation of Herbicides in the Establishment of Alfalfa, Ladino White Clover, and Crownvetch1
Authors: Cope W. A. , Waldrep T. W. , Chamblee D. S. , Lewis W. M.
Published: July 2010

Five experiments were conducted to determine the effects of herbicides on seedling injury and on weed control in the establishment of alfalfa (Medicago sativa L.), ladino clover (Trifolium repens L.), and crownvetch (Coronilla varia L.) in North Carolina. Six treatments with commercial herbicides were included in the series of tests, and a number of other commercial and experimental herbicides were included in one or more of the tests. Two of the five tests were spring seeded to determine the feasibility of using herbicides for successful spring seeding in the area as opposed to the standard practice of fall seeding. Each herbicide was tested in either a preplant incorporated, preemergence, or postemergence application. Herbicide effects were measured in terms of legume stands, vigor, and injury ratings. All the herbicides caused some injury but certain herbicides were only slightly injurious while giving excellent weed control. In prepllant incorporated applications, S‐propyl dipropylthiocarbamate (vernolate) and S‐ethyl dipropylthiocarbamate (EPTC) provided excellent weed control and insignificant injury to all legumes. The higher of two rates of vernolate and EPTC were only slightly more injurious to the legumes than the lower rates. Preplant incorporated treatments of N‐butyl‐N‐ethyl‐a,a,a‐triflouro‐2,6‐dinitro‐p‐toluidine (benefin), 4‐(methylsulfonyl)‐2,6‐dinitro‐N,N‐ dipropylaniline (nitralin), and a,a,a‐triflouro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine (trifluralin) generally gave low injury, but effects were variable for tests and legume species, especially at the higher rate. Postemergence treatment with 2‐sec‐butyl‐4,6‐dinitrophenol (dinoseb) caused little injury in certain tests but resulted in severe defoliation in others, with the least injury to alfalfa and the most to crownvetch. None of the herbicides used in preemergence applications gave good weed control without severe legume injury. There were no readily apparent differences between fall and spring effects of the herbicides. Injury to legumes in one test on sandy soil was generally greater than in the four tests on clay soil.
Effects of Plant Density on Two Varieties of Kenaf in the Georgia Piedmont Region1
Authors: Massey John H.
Published: July 2010

Kenaf (Hibiscus cannabinus L.) is being investigated as a prospective new annual paper pulp crop. ‘Everglades 71’ and ‘Guatemala 4’ kenaf were grown in 50‐cm rows to study the effect of plant densities of 6.6, 8.8, 13.2, and 26.2 plants/m2 on stem yield, stem diameter, and plant height. Stem yield of Everglades 71 was higher in 1 of 3 years, but with 3‐year averages, varieties did not differ in any characteristic studied. Stem yield at 26.2 plants/m2 was higher than at other densities in 1 of 3 years. Basal stem diameter decreased as plant density increased, but plant height was not affected.

The results of this experiment indicate that to avoid excessive plant branching at low densities and lodging of small plants at high densities, an intermediate plant density might be preferable.
Internal Leaf Water Status and Transport of Water in Rice Plants1
Authors: Tomar V. S. , Ghildyal B. P.
Published: July 2010

Rice (Oryza sativa L.) is generally grown continuously submerged in lowland soils and under rainfed conditions in upland soils. The objective of this study was to relate transpiration rate and leaf water potential to relative water content. This information may be useful in predicting the effect of soil moisture stress on growth and yield.

Rice variety ‘IR‐8’ was grown in the greenhouse for 50 to 60 days under submergence and N⅓ bar soil matric potential, and then allowed to wilt.

The pressure potential of leaves approached zero at a total water potential of about −19.5 bars, corresponding to 0.33 relative water content. Leaves experienced a change in cell elasticity at about 3 bars pressure potential and −10 bars total water potential

Transpiration rate decreased with leaf water potential, but it was independent of depletion of soil moisture content above 0.21 and 0.18 for plants grown in submerged and unsaturated soil conditions, respectively. These moisture contents correspond to −0.8 bar and −2.0 bars matric potential. Further depletion in moisture content of both soil moisture regimes resulted in a marked decrease in leaf water potential and in transpiration. Trans. port of water in the rice soil‐plant system was affected more by plant factors under flooded conditions than under unsaturated soil conditions.
Effect of Cercospora Leaf Spot of Peanuts on Forage Yield and Quality and on Seed Yield1
Authors: Cummins D. G. , Smith D. H.
Published: July 2010

Epidemics of Cercospora leaf spot reduce the forage and seed yield of peanuts (Arachis hypogaea L.). The purpose of this study was to determine the effect of different levels of control of Cercospora leaf spot disease on defoliation, forage yield, quality, mineral composition, and seed yield of peanuts. Adapted peanut cultivars were grown according to recommended management practices in the Coastal Plain Region of Georgia during 1971 and 1972. Three foliar fungicides (benomyl 50W, chlorothalonil 75W, and copper‐sulfur dust) were compared with an unsprayed control. Fungicides were applied on a 14‐ day schedule, with five applications in 1971 and six applications in 1972. Benomyl and chlorothalonil gave significantly better control of Cercospora leaf spot than copper‐sulfur dust as evidenced by reduced defoliation. Copper‐sulfur dust was superior to the unsprayed control. As a consequence of disease control (very little defoliation), forage yields, in vitro digestibility, protein content, and seed yields were higher, and forage fiber content was lower. Higher calcium levels in forage were associated with good disease control in both years; Mg, Mn, Fe, Al, and Mo were higher in only 1 year. These differences between years could have been due to the use of different peanut cultivars. Several elements (P, B, Zn, Sr, Ba and Na) were not changed as a result of leaf spot control in either year. During both years, potassium decreased with control of leaf spot. Higher levels of Cu were observed in the forage treated with copper‐sulfur dust in both years. Thus, control of Cercospora leaf spot in peanuts was accompanied by an increase in yield and quality of forage and yield of seed, and levels of control achieved were highly correlated with yield and quality.
Influence of the Nitrogen Fertility Level on Tricholoma Fairy Ring Development in Merion Kentucky Bluegrass (Poa Pratensis L.)1
Authors: Beard J. B. , Vargas J. M. , Rieke P. E.
Published: July 2010

Higher application rates of water soluble nitrogen stimulated the development of fairy rings (Tricholoma sordidum Fr.) in a mature ‘Merion’ Kentucky bluegrass (Poa pratensis L.) turf. The stimulation occurred in plots receiving 3.9 kg or more of nitrogen per are applied annually. Although the increase in Tricholoma fairy ring development was associated with a general decrease in the soil pH, the response was attributed to the more direct effect of the nitrogen fertility level.
Carbon Dioxide Uptake by Wide‐Row Grain Sorghum Computed by the Profile Bowen Ratio1
Authors: Allen L. H. , Hanks R. J. , Aase J. K. , Gardner H. R.
Published: July 2010

A method for computing CO2 uptake by an irrigated crop of wide‐row grain sorghum (Sorghum bicolor (L.) Moench, var. ‘RS‐610’) was devised from measured profiles of temperature, water vapor, and CO2 over the crop. The crop Bowen ratio, β and the ratio of photochemical heat flux density of carbon dioxide fixation to latent heat flux density, α, were determined from profiles of points, rather than from just two points. We call this method the profile Bowen ratio. The parameters α and β were used with the energy balance equation to compute the flux density of CO2 to the crop as a function of solar radiation, which itself was a function of time of day. CO2 flux density plotted as a function of solar radiation (or time of day) was lower at the highest radiation loads (midday) than at 1000 or 1400 hours. The lower CO2 flux density at midday may be the result of more mutual leaf shading in this crop geometry at high solar elevation angles. The CO2 flux density curve also showed concave curvature at the radiation loads concomitant with early morning and late afternoon hours when much of the solar energy was penetrating to ground in this east‐west row crop. Finally, computed daily CO2 fluxes were reasonably close to the CO2 equivalent of dry matter accumulation rates plus estimated respiration.
Emergence and Yield of Beans Planted with a Seed‐Orienting Planter1
Authors: Hayden C. W. , Bowers S. A.
Published: July 2010

Recent observations from an unrelated bean (Phaseolus vulgaris L.) field experiment indicated a possible relationship between emergence and seed orientation. To test the benefits of a “lay flat” orientation, a furrow opener was developed that horizontally orients bean seeds at uniform soil depths. Beans planted through this furrow opener emerged through the soil crust sooner and in significantly greater numbers than did those planted with a standard two‐disk furrow opener. Oriented and un‐oriented plantings of dry and snap beans did not differ in final total emergence. Nevertheless, early snap bean yields were greater from the seed‐oriented plots. Increased yield was due to earlier emergence, and uniform depth of planting. On uncrusted soil, seed orientation did not significantly increase dry bean yield.
Energy Balance Comparisons of Wide and Narrow Row Spacings in Sorghum1
Authors: Chin Choy E. W. , Kanemasu E. T.
Published: July 2010

A sorghum (Sorghum bicolor L. Moench.) canopy has been described as a wick; hence, its evapotranspiration would depend to a large extent on its energy supply. The objective of this study was to determine the effect of row spacing on the energy balance of sorghum.

Measurements were made on wide (0.92 m) and narrow (0.46 m) spaced rows of sorghum with equal linear plant density (12 plants/m). Evapotranspiration (lysimeter), net radiation, and soil heat flux were measured. Sensible heat flux was obtained as a residual in the energy balance. Seasonal evapotranspiration was about 10% more from wide row than from narrow row sorghum. High rates of evapotranspiration were maintained on wide row sorghum by row advection during the first part of the growing season and large‐scale advection during the latter part of the growing season. This study suggests that sensible heat and, consequently, evapotranspiration can be reduced by narrow row spacing in sorghum.
Differential Iron Absorption Efficiency of Peanut (Arachis Hypogaea L.) Cultivars Grown on Calcareous Soils1
Authors: Hartzook A. , Karstadt D. , Naveh M. , Feldman S.
Published: July 2010

The commonly observed chlorosis of plants grown on calcareous soils often has been treated effectively by use of iron chelates. Genetic variability for efficiency of utilization of iron on such soils has also been found. Three inefficient commercial cultivars and five efficient experimental cultivars of peanuts (Arachis hypogaea L.) were compared under treated (Fe EDDHA) and untreated conditions for yield and market quality of pods. The gain in yield for chelate treatment ranged from 22 to 210% for the commercial cultivars but only 8 to 18% for the efficient cultivars. Yields of untreated efficient cultivars were comparable to those of treated inefficient ones, suggesting that use of the former would be economically preferable.
Analysis of Sampling Errors with Traversing Radiation Sensors in Corn Canopies1
Authors: Sinclair T. R. , Desjardins R. L. , Lemon E. R.
Published: July 2010

A traversing system with a fast responding, photocell light sensor was used to measure mean irradiance in corn (Zea mays L.) canopies. Data were recorded by digital and analog recorders to analyze the sampling problems with a moving sensor. Sampling rates of once every 4 seconds for a row‐planted crop and once every 8 seconds for a uniformly planted crop were required to yield satisfactory mean irradiance values from a fast responding sensor. In addition, sensors with time constants at least as long as 8 seconds could be used to measure mean irradiance. Therefore, we recommend that the sampling rate for a traversing sensor in a maize leaf canopy be at least as frequent as the time constant of the sensor, but in any case the sampling rate does not need to be any more frequent than once every 4 seconds.
Effect of Inoculum Rate on Competitive Nodulation of Glycine max L. Merrill. II. Field Studies1
Authors: Weaver R. W. , Frederick L. R.
Published: July 2010

To provide a scientific basis for predicting successful competitive nodulation of soybeans (Glycine max L. Merr.) by Rhizobium japonicum, the quantitative relationship between soil and inoculum rhizobia, in nodule formation, was determined in the field. Soybean seeds were planted at a rate of 1 seed/2.5 cm of row and were inoculated with up to 3.3 ✕ 1038 R. japonicum cells/2.5 cm of row. Field plots were grown on six soils in Iowa having a range of soil rhizobia populations of 1.2 ✕ 101 to 2.3 ✕ 105/g of soil. Numbers of nodules on tap and lateral roots of soybeans grown on soils containing fewer than 12 rhizobia/g were increased when inoculation rates exceeded 3.3 ✕ 104 cells/seed. Neither numbers of nodules nor total nodule mass was increased by inoculation of soybeans grown on soils containing more than 1 ✕ 103 rhizobia/g. When an inoculation rate of 3.3 ✕ 106 rhizobia/seed was used on soybeans grown in soils with fewer than 12 rhizobia/g and in soils with approximately 1 ✕ 103 rhizobia/g, the inoculum strain produced, respectively, 65% and 35% of the nodules. From our results it may be predicted that if the inoculum rhizobia are to form 50% or more of the nodules an inoculum rate of at least 1,000 times the soil population (per g soil) must be used. Commercial inoculants in the United States probably are not supplying adequate numbers of rhizobia for successful competitive nodulation of soybeans grown on land previously cropped to soybeans.
Flowering Behavior and Seed Development in Four Desmodium Species1
Authors: Chow K. H. , Crowder L. V.
Published: July 2010

A knowledge of flowering behavior and seed production would be helpful in formulating intra‐ and interspecific breeding programs of Desmodium species. Selections of D. canum (Gmel.) Schin. and Thell., D. intortum (Mill.) Urb., D. sandwicense E. Mey., and D. uncinatum (Jacq.) DC. were grown in controlled environments and in the glasshouse at Ithaca, New York to investigate plant response to photoperiod and to study ovule and seed development.

D. sandwicense was day‐neutral. D. intortum and D. uncinatum flowered under short days of less than 12 hours. D. canum needed at least 12 hours to induce flowering under artificial light of 21,520 lux (2,000 ft‐c). The species is considered day‐neutral, however, since profuse flowering occurred under natural light of 15.2 hours and since it flowers under shorter days in tropical and subtropical areas. The four species had perfect flowers borne on indeterminate racemes. Anthers of D. canum dehisced in midafternoon with 14 to 15.2 hours of light in the glasshouse. Under 11 hours of light the other three species dehisced 6 to 8 hours before the end of the dark period in the growth chamber. A tripped flower wilted quickly and the standard petal folded over the stigma within 1 hour. Without pollinators, flowers generally did not trip, but seed set exceeded 50%.

After fertilization, the ovule length:width ratio increased rapidly for 4 to 6 days, then declined as broadening occurred. The epicotyl, hypocotyl, and cotyledons became visible within 5 days. At 17 days after pollination seed coats became impermeable on drying of seeds. Before the seed reached maximum weight at about 28 days, 90% or more had hard seed coats. Seed were viable 20 days after fertilization when scarified, and germination rapidly increased thereafter to about 30 days. There was no dormancy period when seed were properly scarified.
Selection for Seedling Vigor in Astragalus cicer L.1
Authors: Townsend C. E.
Published: July 2010

The use of cicer milkvetch (Astragalus cicer L.) as a forage legume is restricted because of relatively poor seedling vigor. If sufficient variation exists within the species for seedling vigor, it may be possible to improve this character through a breeding program. Therefore, the objectives of this study were to determine (1) the variability in speed of seed germination and total germination in the laboratory at two alternating temperature treatments, 5–20 C and 15–25 C; (2) the variability in speed of seedling emergence and total emergence in the greenhouse and field; and (3) the relationships among these characters. About 80 polycross progenies, representing 3 basic breeding populations, were evaluated. The populations comprised polycross progenies selected for superior, average, and below‐average vigor. Highly significant differences existed among progenies for speed of seed germination and seedling emergence over all environments. Simple correlation coefficients between the various characters generally were significant, but of a relatively low predictive value. There is a great need for a laboratory technique that will give a reliable measure of seedling vigor under field conditions. Variation among progenies for seedling vigor was large enough to indicate that improvement can be made in cicer milkvetch for this character.
Crested Wheatgrass Yields as Influenced by Water Conservation Practices1
Authors: Bleak Alvin T. , Keller Wesley
Published: July 2010

Evaporation of water Irom the soil surface is a major economic loss to the western United States, because water is the primary limiting factor in plant growth on arid and semiarid rangelands. ‘Nordan’ crested wheatgrass (Agropyron desertorum (Fisch. ex Link) Schult.) planted in rows 1.1 m apart; the effect on total herbage yield of a gravel mulch, a sheet metal “mulch,” close rows of grass, and cereal grain seeded between the grass rows was determined for a 2‐year period. Some treatments received different rates of N fertilizer. Sheet metal between the rows, covering 86% of the land surface, increased mean 2‐year yield about 112% over clean cultivation (check). A gravel mulch 1.5 cm deep increased mean yield about 16%. Close rows of grass and cereal grain between the grass rows also increased total yield. Benefit from nitrogen at 22, 44, or 66 kg/ha per year was minor. Benefit from the mulches was greater the second year than the first.
Early Growth of Grain Sorghum as Related to Manganese Nutrition1
Authors: Ohki K.
Published: July 2010

Influence of Mn nutrition on sorghum [Sorghum bicolor (L.) Moench.] was investigated to determine the effects of Mn on early growth and define Mn deficiency symptoms under controlled conditions of nutrient solution culture in the greenhouse. Sorghum plants were grown in the greenhouse in nutrient solution containing eight Mn levels from O to 4,000 μg Mn/liter with all other essential nutrients supplied at adequate levels.

Growth retardation determined from plant height measurements resulted prior to the development of visible Mn deficiency symptoms. In addition to the usual Mn deficiency symptoms of interveinal chlorosis, symptoms on sorghum Dekalb ‘BR 64’ included brown‐reddish pigmented bands in interveinal areas following chlorosis. Under slight Mn stress conditions, Mn deficiency symptoms decreased hi severity from young to older leaves.
Decontamination of Surface Soil Containing Strontium‐901
Authors: Haghiri F.
Published: July 2010

The effectiveness of “Dresinol‐40,” “Dresinol‐205,” and “Vinsalyn‐100 Emulsion” materials for immobilizing 00Sr(00Y) adsorbed by soil surface in a form not available to plants was examined. These materials appeared to form a satisfactory crust with soil particles. Spray application of the emulsion material reduced the uptake of 90Sr90Y) by oat (Avena sativa L.) shoots by as much as 56%. However, the percent reduction was not high enough to justify their use as agents for decontaminating surface soil containing radioactive strontium.