bluuebunny/crossref_metadata_2025 huggingface dataset:
Forage Yield and Percent Cell Wall Constituents of Pensacola Bahiagrass as Related to N Fertilization and Clipping Height
Authors: Stanley R. L. , Beaty E. R. , Powell John D.
Published: July 2010

‘Pensacola’ bahiagrass, Paspalum notatum, Flugge, is widely grown in the Southeast but little is known about the influence that cutting height has on forage yield and forage quality. The effect of height of clipping and N fertilization rate on yield and cell wall constituents was measured over a 2‐year period on an established stand of Pensacola bahiagrass growing on a loamy sand (Psammentic paleudults) which was fertilized annually with 0, 84, 168 and 336 kg/ha of N and clipped monthly at heights of 0, 2.5, 5.0, 7.5, 10.0, and 12.5 cm above the stolons. Highest forage yields were obtained when forage was harvested at ground level and yield was least when harvested at 10.0 or 12.5 cm. Cell wall constituents of the forage ranged between 70 and 72% and were not influenced by N fertilization or clipping height. Forage from the first harvest was lower in cell wall constituents than all later harvests. The data suggest that harvesting close to the soil will increase yields but quality as measured by cell wall constituents will be largely unchanged by N application or clipping height.
Effect of Ammonium to Nitrate Ratio on Growth and Pigment Development of Kentucky Bluegrass Cultivars1
Authors: Nittler L. W. , Kenny T. J.
Published: July 2010

Red pigment development or lack of development in leaf sheaths is a useful characteristic for testing cultivar purity of Kentucky bluegrass, Poa pratensis L. However, additional knowledge is needed on the effect of nutritional and environmental conditions on expression of this characteristic so that conditions can be used that will produce the most precise and consistent results. Therefore we grew Kentucky bluegrass seedlings in sand and supplied them with solutions in which 10, 25, 50, or 75% of the N was NH4 and the remainder was NO3.

Growth and pigment development were affected by the ratio of NH4 to NO3 in nutrient solutions and cultivars differed in both characteristics. Red pigment development, as determined by percentage of tiller height showing red color, was greatest when plants .were grown with a nutrient solution in which 75% of the N was NH4. Growth, as determined by tiller height, was less for plants grown with the 75% NH4 solution than for those grown with the other three solutions.

Tiller height does not appear to be a very useful characteristic for cultivar purity testing, but red pigment development is very useful. The nutrient solution to use will depend on what cultivars are to be tested. In some cases it will be desirable to grow two or more groups of seedlings and use a different nutrient solution on each.
Response of Wheat Cultivars to Liming in Some High Al Oxisols of Rio Grande do Sul, Brazil1
Authors: Martini J. A. , Kochhann R. A. , Gomes E. P. , Langer F.
Published: July 2010

The objective of this field study was to determine the yield response of wheat (Triticum aestivum L.) to the direct and residual effects of liming in relation to variety, soil acidity, Al toxicity, P availability, and disease incidence in five Oxisols of Rio Grande do Sul, Brazil under successive wheat‐soybean (Glycine max L. Merrill) cropping.

This work was carried out under field conditions using various limestone treatments arranged in a randomized block design and replicated four times. Plots were 6 m long ✕ 2.4 m wide with 12 rows planted 20 cm apart at the rate of 90 kg/ha. The soils used in this investigation were in the suborder Udox.

While Brazilian wheat varieties developed under acid soil conditions tended not to respond to liming due to their tolerance to exchangeable Al and possibly Mn, wheat varieties from other countries, developed under less acid soil conditions, did respond significantly to liming because of their susceptibility to soil Al and possibly Mn. Some Brazilian wheat varieties did respond to liming under high soil acidity and exchangeable Al levels. Liming to bring soil pH between 4.8 and 5.7 and reduce toxic Al levels below 1.5 meq/100 g was a more valid criterion than raising soil pH to neutrality in order to maximize yields. Liming to pH 5.7 or higher increased the incidence of Ophiobolus graminis and a soil‐borne mosaic.
Influence of Management and Season on Fate of N Applied to Golf Greens1
Authors: Brown K. W. , Duble R. L. , Thomas J. C.
Published: July 2010

Because golf greens are constructed of very sandy soil mixtures over a gravel and tile drainage system and subjected to heavy irrigation schedules, there is a high potential for loss of applied N through leaching. This study was undertaken to determine the influence of management practices during different seasons on the fate of N applied to golf greens. Small isolated golf greens (3 m on a side) were constructed according to USGA specifications and equipped with drainage and runoff collection systems. Mixtures of sand and Houston black clay soil (Udic Pellusterts) were used in some plots while others were made of a Tabor sandy loam soil (Udertic Paleustales). All plots were planted with Tifdwarf Bermudagrass (Cynodon dactylon L). N sources were applied at various rates during different seasons. The golf greens were irrigated at three different rates. Leachate and runoff samples were analyzed for NO3 to evaluate the influence of management practices on N losses from the golf greens. The results show that N losses and concentrations of NO3 in the leachate immediately after application of soluble sources were a function of the rate of N and water applied. When the irrigation rate was kept at or near the evapotranspiration rate, the loss of NO3 from inorganic soluble sources was minimized. The irrigation rate did not affect the NO3 losses from organic sources. Seasonal studies indicated that losses and concentrations of NO3 were highest in winter. This appeared to be associated with the large volume of water which leached from the plots during the season. It was concluded that N losses and NO3 concentrations could be lowered by: using organic sources of N; reducing irrigation rates to equal the evapotranspiration rate; and decreasing fertilizer rates during periods of slow growth.
Evaluation of Seed Treatments to Enhance Pima Cotton Seedling Emergence1
Authors: Buxton D. R. , Melick P. J. , Patterson L. L. , Godinez C. A.
Published: July 2010

Previous research has shown that germination of cottonseed (Gossypium spp.) can be improved during low temperature by treating seed with gibberellic acid (GA3), kinetin, or by elevating the seed moisture level. The work reported here was conducted to evaluate these seed treatments as aids to improving seed germination of G. barbadense L. (‘Pima S‐4’) and to determine if they enhance seedling emergence in fields with low soil temperatures. Soaking seed in water for 6 hours before chilling at 5 C significantly reduced visual chilling injury. Both kinetin and GA had little effect on % germination, but vigor of germinating seed was increased in the laboratory when seed were soaked for 3 hours in 0.1 or 1.0 mg/liter kinetin, or 100 or 500 mg/liter GA.

When similar seed treatments were evaluated in several field plantings with low soil temperatures, neither chemical improved the number of seedlings emerged or the time required for emergence. GA at the level that promoted seed vigor in the laboratory resulted in greatly reduced emergence because of spindly growth. Soaking seed in water before planting generally reduced emergence with the degee of reduction directly related to length of soaking. Seed that were soaked for 3 hours showed abnormal development of cotyledons and reduced dry wt. compared to nonsoaked seed. Thus these seed treatments cannot be recommended as aids to enhance Pima cotton seedlings emergence.
Regulation of Grain Yield by Photosynthesis in Maize Subjected to a Water Deficiency1
Authors: McPherson H. G. , Boyer J. S.
Published: July 2010

Since the physiological mechanisms responsible for yield losses under dry conditions are unknown, especially for grain crops, we attempted to identify them in maize (Zea mays L.) subjected” to a water deficiency during most of the grain filling period. The plants were grown in a controlled environment capable of providing yields comparable to the field. Grain yield, dry weights of shoots and roots, apparent photosynthesis, and leaf water potentials (Ψw) were determined. Shortly after tasseling, water was withheld from the soil of half the plants until Ψw had decreased to —18 to —20 bars, where Ψw remained until maturity. Apparent photosynthesis became virtually zero at these Ψw. However, grain yield was 47 to 69% of the control yield. At low Ψw, the grain developed partly at the expense of photosynthate accumulated prior to the desiccation period. Since grain development is dependent entirely on translocation in maize, this indicated that translocation continued despite the cessation of apparent photosynthesis. The parameter most closely related to yield was dry matter accumulated during the entire growing season rather than that accumulated during grain fill alone. We conclude that translocation it less inhibited than photosynthesis during drought, and that the total photosynthetic accumulation for the growing season controls yield during a drought that does not disrupt the flowering process.
Effects of Snowmobile Traffic on Several Forage Species and Winter Wheat1
Authors: Ryerson D. K. , Schlough D. A. , Foresman C. L. , Tenpas G. H. , Pendleton J. W.
Published: July 2010

Experiments to determine the effects of snowmobile traffic on plant species, frequently grown in heavy snow‐belt regions, were conducted over 3 years in northern Wisconsin. Plant species tested during the trials were: alfalfa (Medicago sativa L.); birdsfoot trefoil (Lotus corniculatus L.); red clover (Trifolium pratense L.); bromegrass (Bromus inermis Leyss.); orchardgrass (Dactylis glomerata L.); and winter wheat (Triticum aestivum L,). The soil is classified as a Typic Eutroboralf, very fine Illitic (mixed). Designated areas of each crop species received varying amounts of snowmobile traffic when snow depths were > 7.5 cm. Soil temperatures, snow compaction, and frost depths were measured. Forage dry matter or grain yields were taken during the following summer. Soil bulk density was determined during two growing seasons as a measure of soil compaction.

Stands of alfalfa, birdsfoot trefoil, and alfalfa/bromegrass treated for two winters with snowmobile traffic showed no detrimental effects on forage yield. Grain yields from winter wheat stands exposed to snowmobile traffic were not reduced below that of check areas. Red clover and birdsfoot trefoil/orchardgrass yields were decreased during 1 year of the trials but were unaffected by snowmobile traffic during 1 other year.

Snow was found to be compacted by snowmobile traffic and soil temperatures colder and more erratic under these areas. Frost penetrated deeper under areas subjected to snowmobile traffic. Soil compaction was not found to be increased by snowmobile traffic.
Estimation of Individual and Total Leaf Areas of Safflowers1
Authors: Sepaskhah A. R.
Published: July 2010

The rapid, nondestructive, and relatively accurate measurement of safflower (Carthamus tinctorius L.) leaf area for physiological and agronomic studies is important. Regression analysis of measurements of leaf length and width were used to develop prediction equations involving three independent variables for estimating individual and total leaf area. Leaf area of plants grown in greenhouse conditions was measured by an optical planimeter. Statistical analysis revealed that a common prediction equation should not be used for both local and non‐local cultivars.

Prediction equations derived from independent variables involving length ✕ width (LW), length squared (L2), or width squared (W2) were satisfactory for estimating total leaf area of both local and non‐local cultivars. Furthermore, the predictive ability of equations for individual leaf area of local cultivars was lowered as the independent variables changed from LW to L2 or W2. Total leaf area could be predicted for all cultivars by measuring only length or width with no loss of accuracy. The variability associated with only width measurements was extremely large compared to length meassurements.
Influence of Soil pH on the Phytotoxicity of Three s‐Triazine Herbicides1
Authors: Adams R. S. , Pritchard D. J.
Published: July 2010

The bioactivity of s‐triazine herbicides is known to vary with soil pH. The purpose of this study was, on one soil type and under similar climatic conditions, to determine the influence of soil pH on the phytotoxicity of atrazine (2 ‐ chloro ‐ 4 ‐ (ethylamino) ‐ 6 ‐ (isopropylamino) ‐ s ‐ triazine), prometryn (2, 4 ‐ bis (isopropylamino) ‐ 6 ‐ (methylthio) ‐ s ‐ triazine and secbumeton (N ‐ ethyl ‐ 6 ‐ methoxy ‐ N ‐ (1‐methylpropyl) ‐ 1, 3, 5 ‐ triazine ‐ 2, 4 ‐ diamine). Greenhouse and field bioassays were used with chemicals applied at four rates ranging from 0 to 4.5 ppm. Soybeans (Glycine max L.) was the bioassay plant in the greenhouse and maize (Zea mays L.) in the field. The soil was Port Byron sil (Typic Hapludolls) and had been in a long term lime study (five rates) for 19 years prior to these studies. Soil pH varied from pH 5.4 to pH 7.4. Soil pH demonstrated the dominant influence on the phytotoxicity of prometryn and secbumeton, but demonstrated much less influence on atrazine toxicity. Organic carbon variation did not effect the phytotoxicity of prometryn or secbumeton, but was the principle factor influencing atrazine phytotoxicity. In the field studies maize was injured severely by high rates of prometryn and secbumeton in the calcareous soil samples, but not in the acid treatments. Maize was not affected by any rate of atrazine or at any pH examined. The influence of pH on s‐triazine toxicity appeared due to differential adsorption or differential hydrolysis by the soil.
Yields and Response of Cereal Crops to Phosphorus Fertilization under Changing Rainfall Conditions1
Authors: Matar A. E.
Published: July 2010

Response of cereal crops to N and P fertilization, grown under the semi‐arid conditions of southern Syria, has been variable and somewhat related to climatic conditions. Two long‐term fertilizer experiments were initiated in 1966 at Ezraa Experimental station, to study some of the P fertilization problems. The first studied interactions between fertilizer use and crop rotation and the second studied direct and residual effects of P on yields of wheat (Triticum aestivum L.) and lentil (Lens esculenta). Response to P depended upon climatic conditions. Data for 1966 to 1972 were used to correlate yields of wheat and lentil or the relative response to P fertilization with rainfall in each month of the growing season or the total of 2 or more months during the respective period. The following results were obtained: (a) A high positive correlation between yields of lentil and amount of rainfall in December (r = +0.90) or March (r = +0.80) and that of wheat with total rainfall in December and January (r = +0.97) was observed. Early predictions of yields should be of great importance to agricultural planning under dry land farming conditions. (b) The relative response of either wheat or lentil to addition of P fertilizers was largely dependent on rainfall distribution. The correlation coefficient (r) between crop response to P and rainfall distribution was opposite in signs to that observed between yields of crops and rainfall distribution. A negative linear relation was found between relative response of lentil to P an amount of rainfall in December (r = −0.89) or in March (r = −0.72). The coefficient of correlation between response of wheat to P and amount of rainfall in December and January was −0.95). In general, greater response to P fertilization was found in the dry and unproductive years, and a negative linear relationship was found between the relative response to P and the absolute yields of wheat or lentil (r = −0.98). It is postulated that P improved cereal crops' tolerance to aridity.
Estimating Leaf Water Potential in Safflower1
Authors: Sepaskhah A. R.
Published: July 2010

The pressure chamber technique is used for rapid measurements of plant water potential. Comparison of this method with thermocouple psychrometer technique is required at various stages of growth for different crops. Xylem water potential estimated by pressure chamber and leaf water potential measured by thermocouple psychrometer were correlated for safflower (Carthamus tinctorius L.) leaves at vegetative and flowering stages of growth in greenhouse conditions. The results of the two methods were linearly related for both growth stages but the equations were different at the 1% level. The values of ordinate intercept were nearly equivalent to the xylem sap osmotic potentials at the both stages of growth.
Tolerance of Bermudagrass Selections to Acidity. I. Effects of Lime on Plant Growth and Mine Spoil Material1
Authors: Lundberg P. E. , Bennett O. L. , Mathias E. L.
Published: July 2010

Non‐fertile acid soils including many strip‐mined spoils are common in the Appalachian region of the USA. Strip mine spoils often have low water holding capacity, no soil structure, and various toxic materials, thus correction of pH and fertility problems may not be economical. Studies involving judicious use of lime and fertilizer and suitable plant species, however, are warranted. The objective of this research was to study the growth of several bermudagrass (Cynodon dactylon (L.) Pers.) selections on strip mine spoil treated with various lime rates. Three cultivars and five strains of bermudagrass were planted in 1 liter pots filled with low pH mine spoil (pH 2.9) treated with six rates of calcitic lime from 2.24 to 13.44 metric tons/ha (1.3 to 7.8 g/pot). All pots were given blanket applications of N, P, K, and Mg, as need was determined from soil analyses. Four harvests were made at approximately 6‐week intervals with oven dry weights of both forage and roots taken at the end of the study. All eight selections showed a significant increase in mean root and forage yields up to 6.72 metric tons/ha lime. Higher lime rates than this did not increase forage yields and resulted in lower root yields. Selections differed markedly in their growth response to various lime levels. ‘Tufcote’ outyielded all other selections at the 2.24 metric tons/ha lime rate, but its highest yield was lower than that of any other selection. ‘P.I. 315904’ and ‘Native 1’ grew best over the range of all lime treatments. Soils in which the various selections had grown had significant differences in pH and residual available nutrients. Bermudagrass was found to tolerate very acidic conditions (pH 3.4). The fact that yield made its most dramatic increase through the first three rates whereas pH increased little may indicate it is really the toxicity of certain elements rather than the low pH which limits bermudagrass growth. This study indicates that Tufcote would be a good choice if pH was as low as 3.4, however, at a nearly optimum pH of 4.5 P.I. 315904 or Native 1 would be a much better choice.
Mineral Utilization by Lambs and Guinea Pigs Fed Mg‐Fertilized Grass and Legume Hays1
Authors: Reid R. L. , Jung G. A. , Roemig I. J. , Kocher R. E.
Published: July 2010

Hypomagnesemic tetany, in both spring and winter forms, is a serious metabolic problem in beef cow herds in the northeast U. S. Control of the syndrome may be achieved by Mg supplementation of the diet, by selecting or breeding plants with the ability to accumulate Mg, or by increasing the concentration of Mg in forages by Mg fertilization or foliar application. The present study was designed to determine whether fertilization of forages with a moderate level of an available Mg fertilizer would effectively increase the concentration of Mg in the forage and improve the Mg status of ruminant animals. A number of grasses and legumes were grown in Pennsylvania and West Virginia, fertilized with kieserite (MgSO4·H2O) at the rate of 112 kg Mg/ha, and harvested as hays in 1973 and 1974. Magnesium concentration in the forages was determined by chemical analysis, and utilization of minerals evaluated with growing wether lambs in balance trials. The use of the guinea pig (Cavia porcellus) as an assay animal for mineral studies with ruminant species was examined in a limited number of trials. Magnesium fertilization increased the concentration of Mg in hays, from a mean value of 0.17 to 0.20% for all forages studied. Fertilization had no significant effect on dry matter digestibility (DMD) of the hays by lambs, and had a variable effect on apparent absorption of Mg. Apparent absorption of Mg was increased significantly, from 24.4 to 29.5%, by fertilization of the grass hays, with no effect (31.8 vs. 31.9% for non‐fertilized and fertilized treatments) in the legume hays. Apparent absorption of Mg, Ca, and P was higher in legumes than in grasses, but there were no differences in absorption of K and S due either to type of hay or to fertilization. Magnesium fertilization resulted in a highly significant increase in Mg retention by lambs, 0.17 vs. 0.28 g/day for non‐fertilized compared to fertilized treatments, for all forages. Retention of Mg, Ca, and P was markedly higher from the legume than from the grass hays. Fertilization had no effect on retention of Ca or P. Fertilization resulted in the most marked improvements in Mg retention from orchardgrass (Dactylis glomerata L.) when harvested (1974) at a vegetative stage in West Virginia and Pennsylvania. DMD values of forages were lower, and apparent absorption and retention of Mg much higher, in the guinea pig than in the lamb in comparative trials. Substantial species differences in the degree and nature of Mg utilization of alfalfa (Medicago sativa L.) hays fertilized with different levels of MgSO4 suggest that the guinea pig would not be a suitable essay animal for mineral availability studies with the ruminant.
Influence of N Stress on Leaf Senescence and N Redistribution in Soybeans1
Authors: Egli D. B. , Leggett J. E. , Duncan W. G.
Published: July 2010

The redistribution of nitrogen from vegetative to reproductive plant parts of soybeans (Glycine max (L.) Merr.) may be one of the factors causing leaf senescence and, consequently, it may have a direct influence on yield. Experiments were conducted for 2 years in a greenhouse hydroponics system to investigate the influence of N removal from the nutrient solution at various intervals during pod filling on the redistribution of N from vegetative plant parts to the seed and on leaf senescence. Plants were harvested at early podfill and at maturity, and all abscised leaves and petioles were collected. Subsequently, total N determinations were made on the abscised leaves and petioles, roots, pods, stems, and seed, thereby permitting an estimation of the redistribution of N. Removal of N early in the pod‐filling period reduced yield, primarily as a result of smaller seed. It hastened maturity and increased the proportion of N in the seed that came from redistribution. Early N removal resulted in earlier leaf and petiole abscission, but none of the N removal treatments had a major effect on the concentration of N in the abscised material. The portion of the N in the seed that came from redistribution ranged from approximately 20% (controls) to approximately 60% (early N removal treatments). Leaves and pod walls were the major sources of redistributed N. Raising the N level in the nutrient solution above that of the control during the filling period had no effect (relative to the control) on any of the parameters measured. The data suggest that the redistribution of N from vegetative to reproductive plant parts influence plant senescence; however, other factors are involved.
Seasonal Log of the Flowering and Podding Activity of Field‐grown Soybeans1
Authors: Hansen Wayne R. , Shibles Richard
Published: July 2010

Little is known about the seasonal and nodal distributions of flowering and podding in soybeans (Glycine max (L.) Merr.). This study was initiated to determine the fruiting activities of two Midwestern cultivars (‘Hark’ and ‘Hawkeye’). They were planted in 102‐cm rows on 18 May at Ames, Iowa, and thinned to appropriate spacings after emergence. Ten plants, spaced equidistant within a row of each of the four replications, were tagged for logging. Pods present at harvest maturity represented 37% of flowers produced in both cultivars. Thirty‐five and 40% of the flowers, and 44 and 40% of the pods abscised in Hawkeye and Hark, respectively. Proportionately greater loss of reproductive structures occurred on branches and on lower main stem nodes in both cultivars. Above node 6 the percentage pod set was virtually constant. Flowering, podding, and seed production were greatest in the lower middle portions of the plant — nodes 6 to 15 on plants with 22 to 26 nodes per main stem. Although flowering differed on a per plant basis, on a land area basis flowering, number of seeds produced, and yield were virtually identical for the two cultivars.
Fruiting in Cotton as Affected by Controlled Boll Set1
Authors: Patterson L. L. , Buxton D. R. , Briggs R. E.
Published: July 2010

Environmental stress and boll load have both been suggested as responsible for the fruiting cessation (cut out) that occurs in cotton (Gossypium hirsutum L.) in mid‐summer in the hot, desert southwestern USA. This study was conducted to examine the influence of boll load on the flowering hiatus. Two cultivars differing in growth habit were planted in the field on an Avondale clay loam soil, a member of the fine, loamy, mixed Hyperthermic Torrifluventic Haplustolls. ‘Deltapine Smooth Leaf’ (DpSL) has a more determinate growth habit than ‘Acala 44–10’ (A‐44). Fruiting was limited during a 90‐day period within each year. Flowers in excess of one flower per plant per time interval, ranging from 2 to 5 days, were removed. Flowers left on plants were tagged and used to calculate boll retention curves. Limiting the number of flowers retained increased total flower production with DpSL more responsive than A‐44. Defloration resulted in cycling of the flower production curve which appeared to be related to relief of moisture stress either from irrigation or rain. Defloration increased both total and percent boll retention during the normal period of cessation of new vegetative and flowering growth with DpSL being more responsive than A‐44. We conclude that boll load exerts a large influence on fruiting behavior of cotton and is the major controlling factor of the cut out period in the cultivars tested.
Evaluation of Root Characteristics in Grain Sorghum1
Authors: Nour Abd‐Ellatif M. , Weibel D. E.
Published: July 2010

Breeding for drought resistance has been limited by the lack of a simple method of screening. Observations in the field cannot be made regularly, nor can the condition be repeated. A laboratory method of testing for drought resistance was needed. To investigate techniques, 10 cultivars of sorghum, Sorghum bicolor (L.) Moench, were planted in washed sand in plastic plots in a growth chamber. Five plants in each pot were fed a nutrient solution for 3 weeks. When they were harvested, wet root weight, root length, root volume, and root/shoot ratio were determined. The purpose of this study was to evaluate the root characteristics among 10 sorghum cultivars known to vary for drought resistance. Significant varietal differences for all characters were found. In general the most drought‐resistant cultivars had heavier root weight, greater root volume, and higher root/shoot ratios. This technique shows promise for identifying drought‐resistant lines, but it involved a considerable amount of time and labor. Root weight would probably be the most indicative and easiest characteristic to determine.
Yield and Protein Content of Rice as Affected by Rate, Source, Method, and Time of Applied N1
Authors: Allen S. E. , Terman G. L.
Published: July 2010

Published results suggest that low rates of applied N may have been responsible for low yields and grain protein of rice (Oryza sativa L.) grown in pot experiments. A series of greenhouse pot experiments was, therefore, conducted at Muscle Shoals, Ala., with rice grown under continuous flooding on Sango sicl (Ochrepic Fragiudult, 5 kg/pot) to study effects of rate and source of applied N (up to 5.0 g/pot) on yield, N recovery, and grain protein. Uniform high rates of other nutrients were applied.

Urea or ammonium sulfate mixed with the soil before planting markedly increased yield of both grain and straw, but NO3‐N was largely lost by denitrification. Rates of 0.5 to 1.0 g of non‐NO3‐N were required for early growth and tillering, factors which were well correlated with grain yield at maturity. Urea and ammonium sulfate topdressed in the floodwater after tillering were more effective than NO3‐N and increased yield of grain proportionately more than straw, as compared to application of all N prior to planting. Grain and straw yields increased curvilinearly with higher N rates, but uptake of N was highly rectilinear with all rates of applied N. Grain protein also increased with rate of N (from 7 to 3% with no N to 9 to 12% with 2 to 5 g of N/pot). Thus, adequate rates and timing of applied N increased both yield and protein content of grain in these pot experiments (without lodging being a problem). These responses varied among sources, methods and time of application, and cultivars; but maximum yield was invariably obtained from rates of N much higher than commonly reported for pot experiments.
Utilization and Redistribution of Zn During Vegetative Growth of Corn1
Authors: Isarangkura Rungruang , Peaslee Doyle , Lockard Raymond
Published: July 2010

Slight changes in availability of soil Zn during the growing season may terminate or initiate Zn stress in plants. For example, under field conditions, visual symptoms of Zn deficiency may disappear after a few weeks, and grain yields of corn (Zea mays L.) may be normal. To determine the degree of recovery of young corn plants after termination of Zn stress and the effectiveness of Zn redistribution during stress, plants were grown in greenhouse sand cultures to anthesis. Levels of Zn ranged from none to 0.1 μg/ml of nutrient solution; Zn supplies were either: (a) withheld until plants had developed to the 4 or 8‐leaf stage; (b) withheld after plants had developed to these stages; or (c) supplied continuously until plants were harvested at the 4, 6, 8‐leaf, or anthesis stages. Leaf area, CO2 assimilation, Zn accumulation, and dry matter yields were determined. Rates of CO2 assimilation (mg/dm2/hour) were decreased to 72% and 10% of the rates in control plants after Zn stress of 19 and 40 days, respectively. Plants stressed for Zn, however, were able to assimilate CO2 at 80 to 90% of normal rates 19 days after Zn was added. Percent decreases in leaf area were similar to those observed for CO2 assimilation. Reductions in both of these growth factors caused severe restrictions in early growth and development. Plants stressed for Zn until reaching the 8‐leaf stage required an additional 15 days to reach anthesis and yielded 50% as much dry matter as control plants. When stressed only to the 4‐leaf stage and then supplied with Zn, plant development to anthesis was delayed 4 days, and dry matter yields were 84% of those for control plants. At anthesis, distribution of Zn in plants that had been placed under stress at the 8‐leaf stage indicated there was extensive mobilization and translocation of Zn to newly developing leaf and stalk tissue.
Solar Radiation Weighting for Weather and Corn Growth Models1
Authors: Linvill D. E. , Dale R. F. , Hodges H. F.
Published: July 2010

Although agriculture is the business of converting solar energy into food and fiber, there has been little use of solar radiation data in regression models of weather and crop growth. A major problem in these studies is the rapidly increasing plant size and growth potential under similar environmental conditions. This has led to the use of standardized measures of Crop Growth Rate (CGR), such as Relative Growth Rate (RGR) and Net Assimilation Rate (NAR), which often overcorrect for crop size. Rather than correct CGR for crop size in the present work solar radiation is weighted to estimate the amount of solar energy intercepted by a corn canopy. Another challenge in solar radiation‐crop growth studies to assess the interaction of solar radiation and plant moisture stress, and this factor is also examined. Weather and corn (zea mays L.) growth measurements in the field at West Lafayette, In., from 1969 to 1971, were used to assess different methods of handling solar radiation in corn growth regression models. Daily solar radiation (S) was weighted with a leaf area function, f(LAI), using Boguer's law and an extinction coefficient determined by K. R. Stevenson and J. W. Tanner to obtain the intercepted solar radiation, SI = S(1 — exp(−0.79 LAI)). This variable was better correlated with total aboveground corn plant growth rates than was either f(LAI) or S. SI was divided by pan (Epan) or Piche evaporation (EPiche), or their square roots, to obtain a derived variable which identified not only the solar energy intercepted by the corn canopy, but also a consideration of atmospheric conditions causing plant moisture stress limitations upon energy conversion within the corn plant. The single variable, SI‐E‐−Piche, was associated with about 45% of the variance in above ground plant growth rates and about 25% of the variability in grain growth rates during the 1969–1971 seasons. The derived variables were tested with 1972 weather and corn growth data and also by pooling data for the eight seasons into three other periods, 1969–1970, 1971–1972, and 1969–1972. The single derived variables, SI‐E½Piche, was associated with 72% of the short period plant growth rate variance in the 1969–1970 period and about 27% in the 1971–1972 period, but it explained practically none of the variability in 1971–1972 grain growth.
Peptidases and Trypsin Inhibitor in the Developing Endosperm of Opaque‐2 and Normal Corn1
Authors: Reed Carl , Penner Donald
Published: July 2010

To determine the nature of the association of trypsin inhibitor content to lysine content in high‐lysine corn (Zea mays L.), the relationship of proteolysis, trypsin inhibitor content, and lysine content was studied during endosperm development in opaque‐2 and genetically similar normal corn. Peptidases with pH optima of 4.0, 5.5, 7.5, 8.4, and 10.0 capable of hydrolyzing α‐N‐benzoyl‐dl‐arginine‐p‐nitroanilide (BAPA) were extracted from the endosperm of developing field grown corn. These peptidases were inhibited by the endogenous trypsin inhibitor and were also unable to hydrolyze bovine albumin, wheat (Triticum aestivum L.) gliadin, zein, and Azocoll (Cal biochem general proteolytic substrate). Significant correlations were found between trypsin inhibitor content and dye binding capacity, a measure of lysine content, between trypsin inhibitor and pH 9.0 optimum peptidase, between the pH 9.0 optimum peptidase and lysine content, and between the pH 5.0 optimum peptidase and water‐soluble protein content. Higher trypsin inhibitor levels found in opaque‐2 corn were associated with higher albumin levels. Normal corn was lower in peptidase, lysine, trypsin inhibitor, and moisture than the genetically similar opaque‐2 line.
Beef Cow‐Calf Performance on Coastal Bermudagrass Overseeded with Winter Annual Clovers and Grasses1
Authors: Hoveland C. S. , Anthony W. B. , McGuire J. A. , Starling J. G.
Published: July 2010

Overseeding winter annuals on dormant ‘Coastal’ bermuda (Cynodon dactylon (L.) Pers) sod will lengthen the productive season and improve forage quality. Such management should result in more animal production, but little information is available for beef cow‐calf performance on overseeded sod. The objective of this study was to determine the performance of beef cows and calves on Coastal bermuda pasture at relatively low levels of N fertilization when overseeded with winter annual species. In a 3‐year southeastern Alabama study on Plinthic Paleudult soil, beef cows and calves were grazed on four Coastal bermuda sod treatments: (a) not overseeded + 112 kg/ha N; (b) overseeded ‘Gulp’ ryegrass (Lolium multiflorum Lam.) + 168 kg/ha N; (c) overseeded ‘Wrens Abruzzi’ rye (Secale cereale L.), ‘Yuchi’ arrowleaf clover (Trifolium vesiculosum Savi), and ‘Autauga’ crimson clover (T. incarnatum L.) + 112 kg/ha N; and (d) overseeded arrowleaf and crimson clovers with no N fertilizer. Grazing season for treatments a‐d began respectively on 2 April, 14 February, 8 January, and 11 March with all ending 5 October. Calf gain in kg/ha/year for treatments a‐d averaged 328, 473, 628, and 460, respectively. Calf annual average daily gain (ADG) of 0.89 kg was higher (P<0.05) on rye‐clover clover than on ryegrass or non‐overseeded Coastal bermuda. Cow gain per ha and ADG were also increased by everseeding with clover. Overseeding sod with rye and clover resulted in nearly double the calf gain per ha and extended the grazing season 3 months longer than that of Coastal bermuda alone. Overseeding clovers alone with no N fertilizer resulted in calf gains equal to those for ryegrass overseeded on Coastal bermuda and fertilized with 168 kg/ha N.
Nitrogen Fertilization in Establishing Forage Legumes1
Authors: Hojjati S. M. , Templeton W. C. , Taylor T. H.
Published: July 2010

Forage legumes play a special role in agriculture in that they fix N and serve as feedstuffs for livestock and poultry. Researchers do not agree, however, concerning need for fertilizer N in legume establishment. We studied the effects of N applied at and shortly after planting of legumes on growth and N fixation and compiled information on current recommendations of agricultural experiment stations in the United States on use of N with forage legumes.

Two greenhouse experiments were conducted. In the first, seed of red clover (Trifolium pratense L.) and bigflower vetch (Vicia grandiflora var. kitalbeliana W. Koch) were planted in sand and given Hoagland's solution at planting or 3 or 6 weeks post‐planting to furnish 28, 56, or 112 ppm N (N1, N2, N3). A comparable N‐free solution (No) was included. In the second, red clover, vetch, and alfalfa (Medicago sativa L.) were seeded into three soils and fertilized with NaNO3 at rates to supply 30 or 60 kg N/ha, and a no‐N check. Plants were harvested at 8 or 9 weeks post‐planting, roots and tops separated, and N fixation estimated by C2H2 reduction. After drying, plant parts were weighed, ground, and analyzed for N. Published recommendations for fertilizing legumes were requested from Agronomy Departments in the United States, and these were summarized.

In trial 1 N1, N2, and N3 plants were larger than N0 plants but, at harvest, fertilized clover plants were fixing only 63, 33, and 6% as much N/pot/hour, respectively, as the latter. Interactions among treatment variables were common. In contrast, level of N applied in experiment 2 did not affect N fixation. Growth was increased equally by 30 and 60 kg N/ha.

Current recommendations concerning N usage on forage legumes vary widely, especially with grass‐legume mixtures. The findings in these greenhouse experiments and the disparities in state recommendations indicate need for further research to more clearly define the conditions, if any, under which use of N with forage legumes is justified.
Quantity and Quality of Triticale and Other Small Grain Silages1
Authors: Bishnoi U. R. , Chitapong P. , Hughes J. , Nishimuta J.
Published: July 2010

Small grain crops are used for ensiling with good results but no information is available on yield and quality of triticale (X Triticosecale Wittmack) as a silage. A field experiment was conducted during two growing seasons, 1974–75 and 1975–76, on a Decatur silty clay loam soil (Rhodic Paleudult) to provide comparative data on quantity and quality of silage produced by triticale, wheat (Triticum aestivum L.), rye (Secale cereale L.), oats (Avena sativa L.) and barley (Hordeum vulgare L.). Silage quality was analyzed by standard laboratory procedures. Forage and silage yields of both triticales were significantly higher than the other small grain cultivars during both growing seasons. Triticale and rye silages contained similar amounts of crude protein, ash, and ether extract. They were significantly lower than wheat but significantly higher than oats or barley in these constituents. No significant differences were found in gross energy, pH, phosphorus, or calcium contents. Triticale can be adequately ensiled and dough stage harvest produced acceptable yield of good quality silage.
Diagnosis and Correction of B Deficiency in Beans and Mungbeans in a Mollisol from the Cauca Valley of Colombia1
Authors: Howeler Reinhardt H. , Flor Carlos A. , Gonzalez Carlos A.
Published: July 2010

On a high pH Mollisol in the Cauca Valley of Colombia, bean (Phaseolus vulgaris) yields were seriously limited by B deficiency, resulting occasionally in complete crop losses. Effective methods of B fertilization were studied and critical levels of B in soil and leaf tissue were determined for diagnosing B deficiency.

When B was applied directly before seeding, beans responded to 1 kg B/ha. However, this rate was not sufficient to supply enough B for subsequent crops, and applications of 2 and 4 kg B/ha were necessary for optimum yields of the second and third crop, respectively. No significant differences were observed between two common B sources, Borax and Solubor. Lateral band placement was slightly superior to central band or broadcast placement. Band application at or shortly after seeding was more effective than that at 20 or 30 days after emergence. Foliar spray with solutions of 0.1 to 0.2% B as Solubor or Borax are recommended when B deficiency does not limit early growth. Critical levels for B deficiency were 20 to 24 ppm B in leaves and 0.65 ppm B as hot water soluble B in soil. Toxicity is expected above 40 to 45 ppm in leaves and 1.3 to 1.5 ppm in soil.

Large cultivar and species differences were observed with respect to tolerance to low levels of B. Black beans were more susceptible than two local red beans. One mungbean (Vigna radiata) cultivar was highly tolerant, showing negative responses to B fertilization.
Effect of Repeated Drought Periods on the Survival of Sorghum Seedlings1
Authors: Nour Abd Ellatif M. , Weibel D. E. , Todd G. W.
Published: July 2010

Drought resistance in crop plants is a highly desired characteristic, but there are no simple laboratory techniques available for screening. The purpose of this research was to study a simple technique of screening for drought resistance in sorghum (Sorghum bicolor (L.) Moench). Ten cultivars were evaluated for drought resistance by subjecting seedlings in flats to four successive cycles of water stress in a controlled environment chamber. The cultivars were selected to represent a range of drought resistance. After the fourth cycle of stress cultivars known to have resistance had the highest survival; e.g., ‘M.35‐1’ had a survival of 65% while ‘Karkatib’ had the lowest survival of 10%. The technique appeared to be a simple and effective method of screening for drought resistance.
Response of Corn to Zn in Ortho‐ and Pyrophosphate Fertilizers, as Affected by Soil Temperature and Moisture1
Authors: Giordano P. M. , Mortvedt J. J.
Published: July 2010

Performance of ortho‐ and polyphosphate fertilizers as carriers of Zn for crops has varied in field trials, suggesting that an interaction might exist with climatic conditions. The purpose of this investigation was to determine the effects of both soil temperature and moisture regimes on the uptake of Zn and P by corn (Zea mays L.) from ZnSO4 granulated with ammonium ortho‐and polyphosphate fertilizers and applied to Nolichucky scl (pH 7.6), a Typic Paleudult soil. In a series of greenhouse experiments, corn grown under various soil temperature (16 to 32 C) and moisture regimes (0.3 to 0.15 atm) showed a marked reduction in dry matter yield, as well as in Zn and P uptake, at low temperature, but varying soil moisture levels had little effect. Uptake of Zn was greater when triammonium pyrophosphate rather than monoammonium phosphate was the source of applied P, but uptake of P from the two P sources was comparable. Although lower Zn uptake appears to be a function of depressed growth under cool soil conditions, it is likely that deficiency arises because early Zn requirements cannot be met when the availabale Zn supply is low. Uptake and yield results further suggest that early growth retardation sometimes attributed to Zn deficiency during cool springs also may be related to suppression of P uptake.
Weed Control for Doublecrop Soybeans Planted with the No‐Tillage Method Following Small Grain Harvest1
Authors: Triplett G. B.
Published: July 2010

The no‐tillage method is used extensively to produce doublecrop soybeans [Glycine max (L.) Merr.] planted after winter grain harvest. Success of this method depends on proper selection and effective application of herbicides for weed control in the second crop. Herbicides were evaluated in the field during three seasons for doublecrop soybean production following winter wheat (Triticum aestivum L.) harvest. Both residual herbicides and herbicides having activity only when applied to the foliage of green plants were evaluated alone and in various combinations in this study. The design of the experiment allowed a partitioning of the effects of herbicides having activity only when applied to foliage and utilized to control weeds present in the wheat stubble from the effects of residual herbicides employed to control growth of weeds emerging after soybean planting and herbicide application. During two seasons, herbicides having activity only when applied to foliage accounted for one‐half and two‐thirds of the yield response to weed control. Residual herbicides accounted for the other part of the yield response. In the third season, very few weeds were present in the wheat stubble at harvest and herbicides active only when applied to foliage had no effect on yield. During this season, effective residual herbicides increased yields significantly. Residual herbicide combinations that included linuton [3‐(3,4‐dichlorophenyl)‐l‐methoxy‐l‐methylurea] and metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazin‐ 5(4H)‐one] were most consistent for weed control and crop yield. Both glyphosate [N‐(phosphonomethyl)glycine] and paraquat (1,1′‐dimethyl‐4,4′‐bipyridinium ion) generally were satisfactory as herbicides used to control existing vegetation. Some of the residual herbicides used in this study also exhibit considerable activity on foliage of plants present but at rates used this was inadequate for maximum crop yields.