bluuebunny/crossref_metadata_2025 huggingface dataset:
Turfgrass Wear Tolerance Mechanisms: I. Wear Tolerance of Seven Turfgrass Species and Quantitative Methods for Determining Turfgrass Wear Injury1
Authors: Shearman R. C. , Beard J. B.
Published: July 2010

The relative wear tolerance of seven cool‐season turfgrass species was determined for both sled (foot‐like) and wheel (vehicular) wear injury. Four methods of evaluating wear tolerance differentials were used: 1) visual rating of wear injury, 2) percent total cell wall content (TCW), 3) percent verdure, and 4) percent chlorophyll/unit area remaining after wear treatment. Manhattan perennial ryegrass (Lolium perenne L.) was most tolerant to wheel wear; Kentucky 31 tall fescue (Festuca arundinacea Schreb.) and Merion Kentucky bluegrass (Poa pratensis L.) ranked second; Pennlawn red fescue (F. rubra L.) and Italian ryegrass (L. multiflorum Lam.) were intermediate; while Cascade chewings fescue (F. rubra var. commutata Gaud.) and rough bluegrass (P. trivialis L.) ranked lowest. The relative ranking for sled wear was slightly different from that for the wheel. Visual ratings indicated that Manhattan, Kentucky 31, and Merion were equally tolerant to sled wear. However, Merion was the most wear tolerant to sled injury, according to ratings based on the percent verdure remaining after treatment. Manhattan and Kentucky 31 ranked second and third, respectively; while, Cascade chewings fescue and rough bluegrass were almost destroyed by the crushing, tearing action of the sled.

Wear tolerance differentiation among species for the four methods tested was in high agreement. However, percent verdure remaining was the preferred method for quantitatively evaluating wear tolerance differentials. It eliminated arbitrary decisions that were inherent in the visual rating system, and involved fewer procedural steps than either the percent TCW or percent chlorophyll content determinations.
Nitrogen‐Sulfur Relations in Soft White Winter Wheat. I. Yield Response to Fertilizer and Residual Sulfur1
Authors: Ramig R. E. , Rasmussen P. E. , Allmaras R. R. , Smith C. M.
Published: July 2010

Sulfur deficiency occurs in some soils in the northwestern United States. Wheat (Triticum aestivum L.) responses to S applications are highly variable and apparently related to N fertilization. Our objective was clarification of this variability by measuring yield responses of wheat (grain and straw) to S applied with a range of N (deficient to excess) for the first wheat crop and monitoring residual S effects on yields of three subsequent wheat crops.

A factorial combination of four rates of S (0, 17, 34, and 68 kg S/ha) as gypsum and four rates of N (0, 45, 90, and 180 kg N/ha) as ammonium nitrate was applied to the first wheat crop at seeding. Wheat was grown in rotation with peas (Pisum sativum L.), wherein the peas were not fertilized and subsequent wheat crops received only a blanket application of N at the optimum rate (56 kg N/ha).

First wheat crops after fertilization did not respond to S when N was deficient or optimum. Sulfur applied with excess N increased straw but not grain yield. Significant N to S interactions were noted. Residual S increased straw yield in all wheat crops and grain yield in 1 of 4 second, 3 of 3 third, and 2 of 2 fourth‐wheat crops. All S application rates gave similar yield increases in the second wheat crop. Residual S from 17 kg S/ha gave responses below maximum in the third wheat crop and residual S from 34 kg S/ha was marginally adequate in the fourth wheat crop.

Wheat response to residual S was influenced by N rates applied to the first wheat crop. High N and S fertilization resulted in early drought and curtailed yields. Gradual release of residual S from recent organic matter apparently provided S at a rate adequate for efficient water use and maximum yield.
Evaluation of Laboratory Methods for Determining Quality of Corn and Sorghum Silages: II. Chemical Methods for Predicting In Vivo Digestibility1
Authors: Marten G. C. , Goodrich R. D. , Schmid A. R. , Meiske J. C. , Jordan R. M. , Linn J. G.
Published: July 2010

Numerous chemical procedures have been suggested for predicting feeding quality of perennial forages but none have been adequately tested for their ability to predict quality of silages of corn (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench, S. sudanense (Piper) Stapf, and their hybrid]. The objective of this phase of a comprehensive study was to determine the value of 20 of these chemical procedures for predicting in vivo digestibility of corn and sorghum silages.

We determined in vivo digestible dry matter (DDM) of 51 silages (17 in each of 3 years) in conventional sheep feeding trials.

Acid detergent fiber (ADF) was the best chemical predictor of in vivo DDM for both corn and sorghum silages. ADF concentration accounted for 80% of the variation in digestibility of sorghum silages and 61% of the variation in digestibility of corn silages. More than half of the variation in digestibility of these silages was also accounted for by calculated cellulose and by crude fiber (CF) concentration. Permanganate lignin accounted for 74% of the variation in digestibility of sorghum silages but only 23% of the variation in corn silage digestibility. Inclusion of crude protein concentration did not improve the digestibility prediction potential of ADF, CF, or the other chemical methods.

The Van Soest summative equation, acid detergent lignin (ADL), ADL/ADF, dry matter solubility in 1 NH2SO4, and solubility in acid pepsin all failed to provide satisfactory estimates of corn or sorghum silage digestibility.

None of the chemical methods equaled our modified Tilley and Terry in vitro DDM as a predictor of in vivo DDM of corn or sorghum silages. However, ADF accounted for only 4% less of the variation in digestibility of sorghum silages and 9% less of the variation in digestibility of corn silages than did in vitro DDM. The relatively low cost of ADF analysis makes it a useful procedure for testing silages that are intended as feeds for ruminants.

We present simple regression equations for prediction of in vivo DDM of corn and sorghum silages from their concentrations of several chemical entities.
Indexes of Sulfur Deficiency in Alfalfa. II. Plant Analyses1
Authors: Westermann D. T.
Published: July 2010

Both soil and plant analysis are diagnostic tools used in identifying S deficiencies; however, soil tests evaluating soil S availability levels are not always successful and deficiencies must then be identified by plant analysis. In addition, the diagnostic tool must be correlated to crop responses under various growing conditions to be useful. Identification of S deficiency on alfalfa (Medicago sativa L.) in southern Idaho permitted the collection of correlation data for both S soil tests and plant analyses. The S soil test correlation data has been previously reported (Agron. J. 66:578–581, 1974). This paper reports the relationships found between the plant S indexes of total S, SO4‐S and total (N/S) ratio, and the response of alfalfa to S fertilization. All data were evaluated by correlation analyses.

The total S and SO4‐S concentrations and the total (N/S) ratio were all found to be satisfactory indexes of S deficiency in whole alfalfa at early bloom. Maximum forage yields were obtained when the tops contained between 0.15 to 0.20% S or 0.05% SO4‐S. Total S and SO4‐S were related and readily interchangeable as indexes. Increases in total S above 0.14% S resulted from the accumulation of SO4‐S. Yield responses to S fertilization were obtained when the total (N/S) ratio was greater than 17 to 18. Total N and total S were not related, but protein N increased linearly as protein S increased. The protein (N/S) ratios were not constant and increased from 17 to 23 as the degree of S deficiency increased.
Stomatal Behavior of Wheat Cultivars in Relation to Their Transpiration, Photosynthesis, and Yield1
Authors: Shimshi D. , Ephrat J.
Published: July 2010

Wheat cultivars were found to differ widely in their stomatal aperture under conditions of adequate moisture supply. A field study was carried out to determine whether these differences were related to short‐term transpiration (measured by a hygrosensor cuvette over periods of less then 1 min), short‐term photosynthesis (measured by the uptake of 14CO2 over a period of 20 sec), long‐term water consumption (determined from soil moisture data over periods of several weeks), and grain yield. Rank correlations between the various attributes were determined. Ten wheat cultivars were used in 1 year, 11 cultivars in the other year. Leaf permeability (measured by means of a viscous‐flow porometer) was well correlated to stomatal aperture (measured by means of silicone rubber impressions), and was therefore used as an index of stomatal aperture. Leaf permeability was significantly rank‐correlated with short‐term transpiration (r = 0.97 to 0.98), with short‐term photosynthesis (r = 0.86 to 0.84) and with grain yield (r = 0.70 to 0.74), but not with water consumption (r = 0.01 to 0.22), which was nearly the same for all cultivars. Yields of the cultivars ranged between 4,000 and 5,200 kg ha−1 in the first year, and between 4,250 and 6,150 kg ha−1 in the second year. It is suggested that wheat cultivars having wider somatal aperture produce higher yields without consuming more water, and that the porometer method may be employed in wheat breeding programs.
Long‐term Nitrogen Rates and Sources Influence Sugarbeet Yield and Quality1
Authors: Halvorson A. D. , Hartman G. P.
Published: July 2010

Application of excessive N to sugarbeet‐producing soils has caused a deterioration in sugarbeet (Beta vulgaris L.) quality resulting in decreased sucrose production. The objective of the present work was to determine what rates of N fertilizer would produce maximum sucrose without sacrificing quality. Influences of repeated applications of sugarbeet yield and various quality factors, in a longtime organic and inorganic N sources and rates since 1953 on irrigated sugarbeet‐small grain rotation, were investigated in 1972 at Sidney, Montana. Nitrogen treatments included barnyard manure (22.4 and 67.2 metric tons/ha), green manure (alfalfa and biennial sweetclover), ammonium nitrate (O, 56, 112, 168, 224, 336, 448, and 560 kg N/ha) and a combination organic and inorganic N treatment (67.2 metric tons barnyard manure plus 112 kg inorganic N/ha).

Highest sucrose production (7.9 metric tons/ha), obtained with 22.4 metric tons/ha of manure, was accompanied by root yields of 47.5 metric tons/ha, with sucrose percentage of 16.6 and petiole NO3‐N concentration (about 6 weeks before harvest) of 663 ppm. For the inorganic N treatments, highest sucrose yield (7.6 metric tons/ha) was obtained with 112 kg/ha of N, with similar results obtained for the green manure treatments. Inorganic N rates greater than 112 kg/ha caused progressive decreases in sucrose yields, sucrose percentage, and dry matter root weights. Dry matter root/top ratios of two or greater coincide with maximum sucrose yields. Increasing the rate of organic or inorganic N applied decreased dry matter root/top ratios.

Results of this study indicate that either barnyard or green manure can be used successfully as a source of N for quality sugarbeet production.
Nitrogen Effects on Crested Wheatgrass as Related to Forage Quality Indices of Grass Tetany1
Authors: Mayland H. F. , Grunes D. L. , Waggoner H. , Florence A. , Hewes D. A. , Joo P. K.
Published: July 2010

Nitrogen fertilization of forage is often accompanied by an increased incidence of grass tetany. A field experiment was established on two calcareous soils to evaluate the effects of N fertilizer on forage quality indices of grass tetany. Nitrogen, as NH4NO3, was applied at 0 and 150 kg N/ha in each of 2 years to separate plots. The crested wheatgrass [Agropyron desertorum (Fisch.) Schult] forage was harvested at regular intervals in the Spring tetany period during 1968 through 1971. Forage was analyzed for inorganic cations, N, total water‐soluble carbohydrates (TWSC), aconitic acid, higher fatty acids (HFA), dry matter, and ash alkalinity — a measure of total organic acids.

Nitrogen fertilizer increased the concentrations (equiv. basis) of forage Mg and Ca more than the increase in K, thus slightly reducing the K/(Ca + Mg) values when compared to the unfertilized forage. However, forage K/(Ca + Mg) values were usually less than the 2.2 value above which the incidence of grass tetany increases rapidly. The potential dietary benefits from the higher Mg concentrations may have been offset by increased concentrations of K, N, HFA, N/TWSC, and aconitic acid, since these parameters are associated with decreased Mg availability to cattle.

Low values for hypothetical blood serum Mg (calculated from forage N, Mg, and K concentrations) coincided with the occurrence of grass tetany in the field. The calculated serum Mg values were lower in the N‐fertilized forage than in the control.

The aforementioned effects of N fertilization should not deter the judicious use of N for optimizing forage yields on semiarid ranges, since other research workers have found that grass tetany losses can be reduced by supplementing animals with Mg.
Prediction of Nitrogen Status of Sugarbeets by Soil Analysis1
Authors: Giles J. F. , Reuss J. O. , Ludwick A. E.
Published: July 2010

The production of high sugar yielding crops of sugarbeets (Beta vulgaris L.) is highly dependent on available N. Excessive N fertilization is frequently cited as a cause of low sugar containing beets, which has become a problem in todays beet industry. The objective of this study was to evaluate the usefulness of N soil tests to predict N fertilizer requirements for this crop.

Fertilizer trials consisting of 4 N rates (0, 70, 140, and 210 kg N/ha) were conducted on 33 farm sites in central and eastern Colorado over a 2‐year period. Soils ranged in texture from sandy loam to clay loam and were generally calcareous at or near the surface having a pH > 7.0. The results show that soil NO3‐N levels measured before planting are useful in estimating the N requirements of the sugarbeet crop. Soil NO3‐N levels were closely correlated with crop yield and sucrose percentage. Regression analysis indicated that yield and recoverable sugar responses to fertilizer N are unlikely when soil NO3‐N levels (0 to 60 cm) are > 130 kg/ha. A linear decrease in sucrose percent resulted from increasing N levels. Soil NO3‐N had a greater effect on sucrose percentage and plant N content than did an equal amount of fertilizer N during both years. An assessment of the NO3‐N content of the soil to at least the 60‐cm depth was found to be an adequate index of soil mineral N availability.
Ratoon Cropping of Sorghum: I. Origin, Time of Appearance, and Fate of Tillers1
Authors: Escalada Rodolfo G. , Plucknett Donald L.
Published: July 2010

This study was conducted to understand the basic growth patterns and tillering behavior of sorghum (Sorghum bicolor (L.) Moench) from plant crop to succeeding ratoon crops in order to attain maximum production with minimum tillage using a particular practice such as ratooning. Under this system, it is possible to have several harvests from a single planting. Time and location of tiller appearance and survival of tillers are important factors in determining the number and vigor of productive tillers which, in turn, influence the growth, development, yields, and longevity of ratoon crops. Successive tiller production and death of tillers affect the perenniality of the crop.

Three cultivars of sorghum ‘Mini‐milo Br 54’, NK 222A, and NK 300 were grown under three plant populations [P1 = 5, P2 = 10, and P3 = 20 plants per 3.7 liter (5‐gal.) pot] and were observed for tillering behavior in relation to the place of origin, time of appearance, duration of early tillers, and to grain and stover yields. Tillers that sprouted early (first and second tillers) originated from basal nodes of the plant. Later tillers (third, fourth, and so on) developed from the nodes adjacent to elongated internodes. Not all tillers which developed, however, reached maturity. Usually the first two tillers died.

Tillers developed earlier in lower populations (P1 and P2) than in the higher population, P3. Cultivar NK 222A produced only two tillers per plant in each population. Compared with tillers of ratoon crops, it took a longer time for the two early tillers of the plant crop to die. Tillers that developed on the upper parts of the stubble were more susceptible to breakage.

More tillers were produced during the plant crop, and the number declined in each succeeding ratoon crop. High plant populations resulted in development of few reproductive tiller, less uniformity in plant height, and a delay in tiller formation. In spite of this condition, increased plant population resulted in increased grain and stover yields. More plants per unit area compensated for the production of fewer tillers. Mini‐milo Br 54 produced the highest number of tillers per plant, followed by NK 222A, and then NK 300 in the first population.

Understanding the basic growth patterns and tillering behavior of a particular sorghum variety, therefore, facilitates management of ratoon crops for maximum production.
Yield and Quality of a Sorghum ✕ Sudangrass Hybrid as Affected by Mixtures of a Grain Sorghum1
Authors: Horner J. R. , Croy L. I. , Denman C. E.
Published: July 2010

Many state seed laws have very close tolerences with regard to genetic purity of sorghum [Sorghum bicolor (L.) Moench] ✕ sudangrass [Sorghum sudanense (Piper) Stapf] hybrids. Genetic purity of sorghum ✕ sudangrass hybrid seed is difficult to maintain because of contamination by outcrossing with foreign pollen or selfing of supposedly cytoplasmic male sterile plants which have some fertility. The effect of reduced genetic purity on yield and quality, as evidenced by in vitro dry matter digestibility and protein content, was estimated by mixing various percentages of seed of a sorghum ✕ sudangrass hybrid and a grain sorghum. Treatments consisted of a hybrid (A Redlan ✕ Greenleaf); the grain sorghum (B Redlan); and 90:10, 80:20, 70:30, 60:40, and 50:50 mixtures of a hybrid and grain sorghum. The study was conducted 3 years in a randomized, complete block design.

Dry matter forage yields were not significantly affected by the various mixtures of a grain sorghum and hybrid. The grain sorghum yielded significantly lower than all other treatments. Dry matter digestibility of all treatments was above 59%, indicating high quality forage, and was not significantly different among treatments within years. There was no difference in protein content between the hybrid and all mixtures within years. Protein content of the grain sorghum was higher than the other treatments and approached significance. The grain sorghum made slower regrowth and was more immature than all other treatments at each harvest date. The results of this experiment indicate that a small reduction of genetic purity in hybrids would not decrease total forage yields or lower quality of forage, as evidenced by in vitro dry matter digestibility or protein percentages.
Amino Acid and Elemental Composition of Sunflower and Pumpkin Seeds1
Authors: Robinson R. G.
Published: July 2010

The research was undertaken because knowledge of the amino acid and elemental composition of sunflower (Helianthus annuus L.) and pumpkin (Cucurbita pepo L) seeds is meager and incomplete. Yet, in contrast to their present use as snacks, both species are widely‐adapted crops of potential use for staple human food. Seeds of the two species were evaluated as foods, to meet major protein and mineral requirements of adult humans. Sunflower cultivars used for birdfeed, human food, and oil were analyzed to discover differences and similarities. Nitrogen percentage to protein percentage conversion factors for various products are commonly based on the N percentages of their major isolated proteins. A single factor (6.25 or 5.30) is used for sunflowers and pumpkin. Using amino acid analyses from this research, a different N to protein conversion factor was calculated for each species.

Sunflower seeds for analyses were harvested from cultivar trial plots grown at four locations for 1 to 4 years. Soils were Typic Hapludoll, Aeric Calciaquolls, and Typic Eutroboralf. ‘Lady Godiva’ pumpkin seeds were harvested for 2 years at Rosemount, Minn. Concentrations of oil were determined by the Soxhlet method, of N by the Kjeldahl method, of other elements by an emission spectrograph, and of amino acids by an automatic amino acid analyzer.

Analyses for 18 amino acids and for 15 elements indicate that < 400 g of either sunflower or pumpkin seeds will supply the total daily protein and mineral requirements, other than Ca and Na, for adult humans. Good nutritive value and simple storage and processing requirements make sunflower seeds a potentially important human food. Sunflower seeds of nonoilseed cultivars were significantly higher than ‘Peredovik’ oilseed cultivar in total protein and in concentrations of 16 amino acids and nine elements. Sunflower pericarps had lower concentrations of oil, protein, ash, and 8 of 15 elements than those of the seeds. Factors to convert N percentage to protein percentage were calculated by dividing 100 by the percentage N in the total amino acids of the seed. The factors for all seed‐lots within each species were nearly identical (6.10 for sunflower and 5.65 for pumpkin). These are better estimates of N conversion values than the single factor presently used for both species.
Recovery of Leaf Water Potential, Transpiration, and Photosynthesis of Cotton During Irrigation Cycles
Authors: Bielorai H. , Hopmans P. A. M.
Published: July 2010

The ability of a plant to recover from temporary and/or prolonged stress and the rate of recovery are of great importance in crop production. However, the information available on this subject is relatively scarce. A study was conducted to evaluate the recovery of irrigated cotton (Gossypium hirsutum L. ‘Acala 15–17’) following soil moisture stress of various durations through the measurements of soil moisture stress (Ψs) using 1) the soil‐moisture retention function, leaf water potential (Ψl), by pressure bomb, and 2) leaf diffusion resistance (Rl), by diffusive resistance porometer. Photosynthesis was measured by an infrared gas analyzer, and transpiration by weighing. The experiment was conducted in a controlled climate room. Leaf water potential (Ψl) was linearly related to that in the soil (Ψs) (Ψl = 0.609 Ψs − 9.77 atm). Diffusion resistance of the leaves showed a curvilinear dependence on Ψs with a marked inflection between −10 and −14 atm. Neither leaf resistance nor transpiration fully returned to pre‐stress conditions after irrigation, and even the partial recovery required several days. Continuous measurements of net photosynthesis also showed a delayed and only partial recovery from soil water stress. It is concluded that the observed reduction in dry matter increase is due mainly to the failure in net photosynthesis recovery after re‐irrigation.
Effects of Harvest Date, Plant Density, and Hybrid on Corn Grain Quality1
Authors: Cloninger F. D. , Horrocks R. D. , Zuber M. S.
Published: July 2010

Corn (Zea mays L.) growers often question the effect of delayed fall harvest on grain quality. Various studies have reported the effect of genetic and environmental factors on the quality of grain, but few have reported on date of harvest. Therefore, the purpose of this study was to investigate the effects of harvest date, as well as planting density, hybrid, year, and their interactions on the quality of corn grain.

Four hybrids were planted at 40,000, 60,000, and 80,000 plants/ha. Harvest dates were October 1, November 1, and December 1 each year of the 3‐year study (1969–71). Grain quality was measured by determining protein and oil content, 1,000‐kernel weight, test weight, and kernel hardness. Standard procedures were used for the first four variables and kernel hardness was determined on a Steinlite Model CK2 corn breakage tester.

The only interactions to show significance were those of year with the other main effects. Protein content was not affected by delayed harvest, but did decline significantly with each 20,000 plant/ha increase in planting rate. Oil content varied more among hybrids (3.44 to 4.16%) than years (3.50 to 3.91%), and declined significantly as the harvest date was delayed (3.80 to 3.68%).

Kernel weight and kernel breakage were closely related to the environment of the particular growing season. The range in 1,000‐kernel weight among years was 68 g, whereas the maximum differences among hybrids was 34 g. Kernel breakage, an indication of kernel hardness, increased as population was increased from 40,000 to 60,000 plants/ha. When harvest was delayed from October 1 to November 1 kernel breakage increased.

This study showed that protein content was not affected by delayed harvest and that kernel breakage was more closely related to the seasonal fluctuations in environmental conditions than to the treatments imposed. On the other hand, oil content showed a 0.12 percentage point decline as harvest was delayed. This decline, although significant, probably has little meaning from the milling point of view since the oil content of corn ranges from 4 to 5% of the whole kernel and not all the oil is extracted in the milling process. However, losses associated with delays in harvest as a result of increased stalk lodging and ear droppage were of greater significance.
Soil Mn Availability to Soybeans as Affected by Mono and Diammonium Phosphate1
Authors: Randall G. W. , Schulte E. E. , Corey R. B.
Published: July 2010

With increasing efforts toward greater soybean (Glycine max (L.) Merr.) production, Mn deficiency undoubtedly will appear more frequently. To determine if Mn deficiency can be alleviated by locally placed common fertilizer materials, monoammonium phosphate (MAP) and diammonium phosphate (DAP) were added to a Mndeficient Sebewa loam (Typic Argiaquoll) in both greenhouse and field studies. Soil and plant analyses and soybean yields were used to evaluate the treatments.

In the greenhouse, soil pH was depressed slightly and exchangeable Mn increased by the ammonium phosphate treatments. The Mn deficiency was alleviated partially by localized applications of 10 or 20 ppm P as DAP or 20 ppm P as as MAP. These treatments produced plants that were significantly larger and showed less severe Mn deficiency symptoms than plants in control pots without P added.

Deficiency of Mn in the field was alleviated by P applications of 17 and 34 kg/ha either as MAP or DAP. Plant weights, leaf Mn concentrations and soybean yields from the P‐treated plots were significantly higher than those from control plots. Plant weights and bean yields from P treatments were not different from the bandapplied Mn treatment (22 kg Mn/ha). However, leaf Mn concentrations resulting from the application of 34 kg P/ha as MAP or from 17 or 34 kg P as DAP were significantly higher than from the Mn treatment.
Cold Hardening and Carbohydrate Composition of Meyer Zoysia1
Authors: Rogers R. A. , Dunn J. H. , Nelson C. J.
Published: July 2010

There are few reports on cold hardening in warmseason turfgrass species. The purpose of our study was to measure changes in cold hardiness and carbohydrate composition of Zoysia japonica Steud ‘Meyer’ turfgrass during fall and winter.

Both rhizome and stolon tissue developed comparable levels of cold hardiness as measured by an artificial freeze test. A significant (P <; 0.05) reduction in percentage survival of tissue occurred at freeze‐test temperatures at or below −6.7 C on September 23 and Octobei 26; and −10.0, −8.9, and −12.8 C on November 30. January 10, and March 13, respectively. Total nonstructural carbohydrate (TNC) concentration of both rhizome and stolon tissue increased during September, remained relatively constant near 50% of dry weight until December, and was reduced to about 15% by March 15. Starch comprised the largest percentage of the carbohydrate fractions and closely followed TNC concentration. Total sugars increased slightly during fall, while reducing sugars remained nearly constant during the entire sampling period.
Determining Density of Maize Canopy from Digitized Photographic Data1
Authors: Stoner E. R. , Baumgardner M. F. , Swain P. H.
Published: July 2010

Plant and soil scientists have devised many methods with varying degrees of success to determine the density of vegetative cover. Canopy density is important in estimating yield of biomass, characterizing vegetative stress, predicting soil losses from erosion, and planning resource management programs. The objective of this investigation was to examine quantitatively the relationship between the densities of maize (Zea mays L.) canopies and the energy reflected by them.

Spectral and spatial data were obtained from color and color infrared (IR) photographs from 10 m above field plots of four growth stages of maize on dark and light‐colored soils.

Leaf area index (LAI) measurements were made in the field. Photographs were used for determining percent ground cover 1) by a point grid technique and 2) by microdensity scanning of the three separate emulsion layers of the color photographs and digital analysis of the resulting data.

A statistical pattern recognition computer program was used to determine the spectral separability of the digitized photographic data and to classify the data into two categories—green vegetation and soil.

Of the emulsion layers of the color IR photographs, classification of the digitized infrared wavelength band best represented the actual percent ground cover. A plot having an LAI of 4.44 had a ground cover of 96.5% as determined by the point grid method and 93.2% by digital analysis of IR data. Classification of data from the visible red (0.59 to 0.71 μm) overestimated percent ground cover and from the green (0.47 to 0.61 μm) underestimated percent ground cover.
An Aseptic Mist Chamber System: A Method for Measuring Root Processes of Peas1
Authors: Smucker A. J. M. , Erickson A. E.
Published: July 2010

Although plants have been grown with their roots in mist chambers and sterile nutrient solutions, these methods have not been combined to provide a system which permits rapid changes in the gaseous composition of an aseptic rhizosphere. The objectives of this study were to design a mist chamber system which would withstand heat sterilization, maintain an aseptic rhizosphere, permit rapid gaseous exchange without altering rootwater relationships, and permit the measurement of morphological and physiological root responses without disrupting the system.

A pyrex glass mist chamber system is described which permitted a complete exchange of the root atmosphere in 5 min. Pea (Pisum sativum L.) seedlings were treated from 6 to 17 days in the aseptic mist chamber. Root respiration, root exudation, and rhizosphere volatiles were monitored. Detection limits were 1.0 ppm of ethanol, 1.0 and 0.25 μg for the TMSi amino acids and sugars.

This system provides for concise control of the rhizosphere and precise measurements of root responses to environmental stresses.
Diffusion and Mass Flow of Nitrate‐Nitrogen into Corn Roots Grown Under Field Conditions1
Authors: NaNagara T. , Phillips R. E. , Leggett J. E.
Published: July 2010

Nitrate‐nitrogen, the most important source of N of non‐leguminous plants, is soluble in soil water and is transported to plant roots by both mass flow and diffusion. It is, therefore, important to evaluate the relative importance of each of these two mechanisms of transport of NO3‐N to plant roots and the environmental conditions under which each is the dominant mechanism of transport. The objective of this paper was to present measurements of plant and soil parameters necessary for estimating accumulation of N grown under field conditions with the use of a theoretical model and to compare estimates of accumulation of N in the corn plant with measured accumulation in the plant.

Plant and soil parameters were measured 37, 49, 76 and 97 days after planting on corn grown under field conditions for use in the theoretical model to predict uptake of N by the roots. The plant and soil parameters measured were volumetric soil water content, concentration of NO3‐N in soil solution, porous diffusion coefficient of NO3‐N in soil, average macroscopic velocity of soil water at plant root surface, radius of root, transpiration rate, and plant root length. In the derivation of the theoretical model it was assumed that the flux of NO3‐N into the root was proportional to the concentration of NO3‐N in the soil solution surrounding the root; the constant of proportionality, k, relating these two quantities has been referred to as the “absorbing power of the root.” A linear relationship between flux and concentration was found to exist up to a concentration as high as 160 μg NO3‐N/cm3 of soil solution for corn grown under field conditions. The proportionality constant, k, was found to decrease with time and/or age of the plant; k values of 0.51, 0.35 and 0.26 cm2/sec were found for three harvest dates corresponding to 34 to 49, 49 to 76, and 76 to 97 days after planting, respectively.

The errors of the predicted uptake of N as compared with measured accumulation were as large as 50% for the individual harvest periods. However, the error was greatly reduced when the predicted values and measured values were summed over the three harvest periods. In general, the predicted uptake values were smaller than the measured values when the measured values of accumulation were less than 1,200 mg of N/plant; the reverse was true when the measured values of accumulation were greater than 1,200 mg of N.
Smoothing Data with Cubic Splines1
Authors: Kimball B. A.
Published: July 2010

Agronomic data frequently requires smoothing in order to obtain a reliable functional relationship for interpolating, predicting, or determining the rate of change of one variable with respect to another. To test whether cubic spline functions could provide satisfactory smoothing, the necessary equations were derived, computer programs written, and several sets of soil temperature and water content data were smoothed.

Cubic spline smoothing displayed the following, advantages: 1) Because spline functions are defined piecewise, they can represent any variable arbitrarily well over wide ranges of the other. 2) The data can be obtained at unequal intervals, so high sampling rates can be used where changes are rapid and low rates where they are slow. 3) Additionally, the gradients derived from cubic spline functions are smoothly joined parabolas, not the abruptly joined straightline segments characteristic of parabolic spline smoothing.
A Model to Predict Winter Wheat Emergence as Affected by Soil Temperature, Water Potential, and Depth of Planting1
Authors: Lindstrom M. J. , Papendick R. I. , Koehler F. E.
Published: July 2010

Establishment of adequate stands of winter wheat (Triticum aestivum L.) in northwest USA is often hampered by low soil temperature or moisture, or by deep planting to reach moisture sufficient for emergence. Because of the wide variability and interactive effects among these factors, it is often difficult to predict the rate and extent of emergence of field plantings. A model was devised to predict emergence time of ‘McCall’ and ‘Nugaines’ winter wheat as a function of soil temperature between 5 and 25 C, water potential down to —10 bars, and planting depth. Predictions were reasonably good when compared with field measurements, particularly at high water potentials and with shallow planting. In general, the emergence rate progressively decreased with lowering of water potential, lowering of temperature from 25 C, or with increase in planting depth. The lower limit or minimum water potential for emergence increased with increasing temperature. Both wheats responded similarly to temperature decreases; however, the emergence rate of each variety responded differently to change in water potential. Differences in varietal response to water potential can possibly be characterized in terms of two parameters in the function describing the water potential effect on emergence.
Effect of Planting Depth, Temperature, and Cultivars on Emergence and Yield of Double Cropped Soybeans1
Authors: Stucky Donald J.
Published: July 2010

Adequate soil moisture may not be available in the first 5 cm of soil for the germination and emergence of soybeans [Glycine max (L.) Merr.] planted immediately after wheat is harvested. Since soil moisture generally increases with depth, deeper planting may be advantageous to help insure an adequate plant population. Three experiments were conducted to determine the influence of planting depth and temperature on the emergence and yield of several cultivars of soybeans. A pot experiment conducted in growth chambers had these variables: (a) nine cultivars from three maturity groups, (b) three planting depths—5, 7.5, and 10 cm and (c) three temperatures—16, 24, and 32 C. The soil medium consisted of a mixture of silt loam, sand, and peat in a ratio of 1:1:1, by volume. The second experiment was a 1973 field experiment which was planted with a no‐till planter in 76 cm rows. The 1973 field experiment involved: (a) three cultivars in different maturity groups, and (b) three planting depths—5, 7.5, and 10 cm. A second field experiment was conducted in 1974 in which doublecropped soybeans were planted with a no‐till planter with the following variables: (a) five cultivars from three maturity groups, (b) two row widths—51 and 76 cm, and (c) three planting depth treatments—5, 7.5, and 7.5 cm covered by 5 cm of soil. Both field experiments were conducted in a Stoy series soil of the fine‐silty, mixed, mesic family in the Albaquic Fraguidalf subgroup. These experiments indicated that (a) most soybean varieties can emerge satisfactorily from depths up to 7.5 cm, providing moisture is not a limiting factor, (b) high temperatures accelerate soybean emergence and although some reduction in percent emergence occurs, it does not appear to be a prohibitive factor, and (c) the highest yields in southern Illinois were achieved with varieties from maturity groups III and IV when planted in 51 cm rows.
Effect of Increasing Foliage and Soil Reflectivity on the Yield and Water Use Efficiency of Grain Sorghum1
Authors: Stanhill G. , Moreshet S. , Fuchs M.
Published: July 2010

The effect of increasing foliage and soil reflectivity on yield and water use efficiency of grain Sorghum crops (Sorghum bicolor (L.) Moench.) grown under arid conditions with stored soil water only, was studied during 3 years of randomized block field experiments. Suspensions of kaolin were sprayed on the soil and/or foliage at different growth stages to select the most effective placement and timing for the treatment. Soil‐only applications were ineffective in increasing yields but canopy sprays resulted in an additional yield of 446 kg/ha, or 11% over the unsprayed controls, averaged over the 3 years of experimentation. The most effective period for foliage sprays started seven weeks after seedling emergence and ended 10 days later, immediately before the panicles emerged. During this period, known to be critical for Sorghum grain yield response to water status, the yield response averaged 2 kg grain/1 kg kaolin applied. Neither the total seasonal water use nor the rate of soil water depletion was affected by the foliage reflectance treatment.

It is concluded that under arid conditions, kaolin suspensions sprayed twice on the foliage of unirrigated grain Sorghum crops during the prepanicle‐emergence stage shows promise as an effective method of increasing grain yield.
New Technique for Measuring the Water Potential of Detached Leaf Samples
Authors: Brown Ray W.
Published: July 2010

Evaporative losses and contamination in sample disks after they are cut from plant leaves often cause errors in measurements of water potential. A new technique for collecting detached leaf disks to measure water potential eliminates most of the errors associated with other methods. The leaf cutter contains a double‐junction Peltier thermocouple psychrometer. When a leaf disk is removed from the plant, it can be sealed immediately against the cavity containing the psychrometer.
Salt Tolerance of Prostrate Summer Cypress (Kochia prostrata)1
Authors: Francois L. E.
Published: July 2010

Prostrate summer cypress (Kochia prostrata L.), a widely distributed perennial shrub in Russia, was imported into the USA to determine its potential as an acceptable forage on the western rangelands. Since considerable acreage of its possible habitat contains salt‐affected soils, a salt tolerance study was done to determine how well suited it was to these saline areas.

Two accessions of Kochia prostrata L., PI 314929 and PI 358941, were tested using soil cultures in the greenhouse. Salinity levels used were 2, 7, 11, and 17 mmho⁄cm. The plants were harvested six times over a 3‐year period. Both accessions proved to be very salt tolerant but PI 358941 was significantly more productive than PI 314929 at all salinity levels. Although sodium and chloride contents approached 50 and 85 meq⁄100 g dry matter, respectively, no salt injury symptoms were visible. Sodium uptake increased proportionately with increasing salinity, whereas chloride uptake was less dependent on salt concentration and appreciably greater than that of sodium.

Since both accessions proved to be highly salt tolerant, they should be well adapted for planting in the salt‐affected western rangelands.
Nitrogen Availability to Wheat as Affected by Depth of Nitrogen Placement1
Authors: Daigger L. A. , Sander D. H.
Published: July 2010

The availability of residual N in the root zone greatly influences the amount of N fertilizer required to optimize winter wheat (Triticum aestivum L.) yields. In order to determine the availability of N at different depths in the root zone, and N placement study was conducted in the field on two soils in western Nebraska, a deep alluvial fine sandy loam (Entic Haplustoll) and a loess‐derived silt loam (Typic Arguistoll). Ammonium nitrate was placed on the soil surface and at depths of 30, 60, 90, 120, and 150 cm. Wheat plants were harvested six times during the spring growing season to determine N uptake. Soil moisture was at field capacity in the spring when experiments were established. While N uptake tended to decrease as the depth of N application increased, total dry matter production was not affected by depth of N placement. Wheat plants easily obtained N placed at depths up to 150 cm. The results indicate winter wheat roots are mostly established during the fall growing season and are in a position to provide N early in the spring for rapid above ground growth.
Irrigated and Nonirrigated Soybean, Corn, and Grain Sorghum Root Systems1
Authors: Mayaki W. C. , Stone L. R. , Teare I. D.
Published: July 2010

Knowledge of rooting patterns of various crops is important in designing irrigation systems and assessing water extraction capabilities. We investigated root depth and distribution under irrigated and nonirrigated conditions for soybeans [Glycine max (L.) Merr. ‘Williams’], corn [Zea mays (L.) ‘Prairie Valley 82S’], and grain sorghum [Sorghum bicolor (L.) Moench, ‘Pioneer 846’].

Soil cores 6.7 cm in diam. were taken to 180 cm deep in the crop row, ¼ row, and ½ row (furrow) for each crop at physiological maturity. The cores were sectioned in 30‐cm increments and washed through 35‐mesh screen (0.73 mm opening), and the roots oven dried. The study soil was deep, barrier‐free, Muir silt loam (fine‐silty, mixed, mesic, Pachic Haplustoll).

Approximately 71, 64, and 86% of the total root dry matter were in the upper 30 cm for irrigated soybeans, corn, and grain sorghum, respectively. Approximately 67, 39, and 79% of the total root dry matter were in the upper 30 cm for nonirrigated soybeans, corn, and grain sorghum, respectively. Only corn did not have roots in the 150 to 180‐cm zone. Seasonal water uses under irrigated conditions (neglecting water flux into or from the root zone) were 65 cm, 65 cm, and 53 cm in soybeans, corn, and grain sorghum, respectively. Seasonal water use was approximately 44 cm by each of the three crops under nonirrigated conditions.
Nodulating and Non‐nodulating Lee Soybean Isolines Response to Applied Nitrogen1
Authors: Bhangoo M. S. , Albritton D. J.
Published: July 2010

Further studies on N fertilization of soybeans [Glycine max (L.) Merr.] were needed for better understanding of the relative capacity of soybeans to fix atmospheric N and utilization of applied or soil N and fixed N. Field experiments with nod and non‐nod Lee isolines were conducted for 3 years on a prelimed Calloway silt loam (fine‐silty, mixed, and Thermic family of Glossaquic fragiudalfs). Nitrogen in the form of NH4NO3 at the rates of 0, 56, 112, 224, and 448 kg/ha was applied each year. Grain and vegetative matter yield, N content and total N uptake showed significant increases from applied N each year. Grain yields of nod Lee from the no‐N treatments equalled those of the non‐nod Lee at the 0 and 56 kg N/ha in 1973 and at the 112 and 224 kg N/ha rates in 1971 and 1972, respectively. Yields of both isolines were highest and similar at the 224 and/or 448 kg N/ha rates each year. Higher grain yield and total N uptake in the non‐nod no N, 56, and 112 kg N/ha rates especially in 1973 indicated utilization of soil and applied N. Utilization of applied and soil N along with fixed N was evident in both isolines each year. Of the total N uptake, the amount of fixed N in the no‐N treatments in 1971 and 1972 was 51.0 and 63.9%, respectively, and was 22.1% in 1973, possibly because of high residual soil N. Symbiotic N fixation decreased practically to zero when N rates exceeded 224 kg/ha. The 56 kg N/ha had little effect on N fixation. Applied or soil N along with fixed N appeared to be essential for maximum soybean yields on poorly drained soils low in organic matter with a strongly acid subsoil. Rates of N applied should be within the range where symbiotic fixation is not inhibited and should be based on the residual soil N.
Evaluation of Protein and Nutritive Fiber Content of Cultivated Russian‐Thistle1
Authors: Farmer David A. , Fowler James L. , Hageman James H.
Published: July 2010

Russian‐thistle (Salsola sp.), a troublesome weed in the arid and semiarid regions of the United States, has been successfully harvested and used as a forage when cultivated forages were limited or unavailable. Over the years, the few published reports of studies of water use efficiency and nutritive value of Russian‐thistle have been sufficiently encouraging to suggest its potential as a forage crop in areas where water resources are limited. Therefore, this study was undertaken to determine the effect of nitrogen fertilization on some of the nutritional qualities of Russian‐thistle.

Russian‐thistle plants were grown in a greenhouse in 15‐liter pots; urea levels corresponding to 0, 28, 56, 84, and 112 kg of N/ha were applied, and all plants were watered uniformly. Under these conditions, no correlations were found between nitrogen application and total crude protein, acid detergent fiber, or acid detergent lignin; nevertheless, average values of 19.8, 34.4, and 6.4 (percent dry weight) were measured for each of these, respectively. In addition, the amino acid composition of the total protein was well balanced nutritionally. Only at the highest nitrogen applications was nitrate observed to approach potentially dangerous levels. Values obtained are comparable to many commonly used forages. Studies to determine the effect of nitrogen and water application on the nutritional qualities of Russian‐thistle under field conditions are underway.