bluuebunny/crossref_metadata_2025 huggingface dataset:
Germination of Cool Season Annual Clovers1
Authors: Evers G. W.
Published: July 2010

Information on the effect of temperature on germination of the major cool season annual clover species adapted to the southeastern United States is limited. Such data would be useful in determining optimum planting dates and reveal differences between species. Seed of arrowleaf (Trifolium vesiculosum Savi.), crimson (Trifolium incarnatum L.), subterranean (Trifolium subterraneum L.), and Persian (Trifolium resupinatum L.) cultivars was placed on indented blotter pads in 90 ✕ 50 cm petri dishes. Petri dishes were placed in a low temperature incubator and subjected to day/night temperatures of 15/5, 20/10, 25/15, 30/20 and 35/25 C with 12‐hour light periods which simulate natural temperatures during clover establishment in the southern states bordering the Gulf of Mexico. Numbers of normal and abnormal seedlings were recorded every 2 days from the 3rd to the 13th day.

Crimson and Persian clover had the fastest germination rate followed by subterranean and arrowleaf. Persian clover was the least responsive to temperature with only 11% difference in germination between treatments by day 13. Crimson clover reached maximum germination across all temperatures most rapidly with only 1 to 4% difference between day 9 and 13, but the number of abnormal seedlings was three to four times greater than the other clover species. Good germination of Persian and crimson clovers occurred at the highest temperature of 35/25 C. This could result in poor natural reseeding if hard seed content and dormancy decrease too quickly after seed maturation to prevent summer seed germination.

Arrowleaf clover was affected most severely by the temperature treatments with maximum germination reaching only 17 and 9% under the 30/20 and 35/25 C treatments, respectively. Therefore, good arrowleaf seed germination occurs later in the fall than the other species which means less fall forage production and increases the risk of seedling damage by an early frost. Subterranean clover germination was depressed only at the 35/25 C treatment with the best germination rate at 30/20 C.
Temperature Response of Seed Growth Characteristics of Soybeans1
Authors: Egli D. B. , Wardlaw I. F.
Published: July 2010

The growth rate and duration of an individual seed are important parameters in the yield production process of a grain crop. Experiments were conducted in the CSIRO phytotron at Canberra, Australia to investigate the effect of temperature on the rate and duration of seed growth and associated plant characteristics in soybeans [Glycine max (L.) Merr.]. Soybeans (‘Fiskeby V’) were grown at 24/19 C until beginning seed growth and shifted to 18/13, 24/19, 27/22, 30/25, and 33/28 C (day/night temperature, 8‐hour day) until maturity. Seed growth rates (SGR) were estimated by harvesting seeds at 5‐day intervals, and from the growth rate of excised cotyledons cultured in nutrient media for 96 hours. The SGR of seed developing on the plant increased from 6.1 to 7.9 mg seed−1 day−1 as air temperatures increased from 18/13 to 27/22 C, but there was no further change as the temperature increased to 33/28 C. Excised cotyledons showed a similar growth rate response to temperature. Exposing the plants to high temperatures (33/28 C) during the period of flowering and pod set reduced SGR (36%) regardless of the temperature during the subsequent seed growth period, suggesting that seed growth is sensitive to temperature levels at these early stages. Seed respiration on a dry weight basis (mgCO2h−1 g−1) was not affected by temperature. The duration of seed growth was not affected by temperatures of 24/19 to 30/25 C but was reduced by 3 days at 33/28 C, and this was associated with accelerated leaf senescence as shown by leaf yellowing and reductions in CO2 exchange rate. Final seed size was reduced from 200 to 151 mg seed−1 at 18/13 and 33/28 C. The data suggest that SGR and duration are relatively insensitive to temperatures ranging from 24/19 to 30/25 when these are imposed after flowering and pod development. The reduction in the duration of seed growth at high temperatures may be one mechanism by which high temperatures reduce yield.
Influence of Potassium on Helminthosporium Cynodontis and Dry Matter Yields of ‘Coastal’ Bermudagrass1
Authors: Matocha J. E. , Smith Leon
Published: July 2010

A study was conducted to investigate K nutrition in relation to occurrence of a leaf spot disease identified as Helminthosporium cynodontis Marig. on ‘Coastal ’ bermudagrass (Cynodon dactylon L. Pers.) grown on sandy soils of east Texas. Previously studied research plots of Coastal bermudagrass production via clipping removal were used. These were located on Darco (Grossaronic Paleudult; loamy, siliceous, thermic) and Cuthbert (Typic Hapludult; clayey, mixed, thermic) soils, typical of those used in forage production in east Texas. The influence of applied K at 112 and 224 kg K/ha with varying P on incidence of the disease, tissue K levels and exchangeable soil K was measured. Disease severity was curvilinearly related to tissue K levels. Midseason tissue K levels of 0.60% or less were associated with progressively increasing disease severity and decreasing dry matter yield. The first increment of 112 kg K/ha decreased disease severity and increased dry matter yield substantially. Phosphorus supply without K appeared to slightly aggravate the disease, possibly due to nutrient imbalance. Longevity of intensified forage production without K fertilization before development of the disease anomaly was soil dependent and varied from two production seasons for the Cuthbert soil to six seasons on the Darco soil. Differences in soil K reserves and soil depth were apparently responsible for the timing of the K related problem.
Post‐Harvest Sucrose Losses in Sugarbeet Roots Treated with Soil‐Injected Ethylene1
Authors: Akeson W. R. , Freytag A. H. , Stout E. L.
Published: July 2010

Sucrose worth millions of dollars is lost annually in the United States during storage of sugarbeet (Beta vulgaris L.) roots from harvest until they are processed. Our objective was to evaluate the effect of treatment of roots with ethylene during the growing season on sucrose loss and change in quality components during storage. Ethylene was injected 20 cm into the soil between rows at the 11‐leaf‐stage of development. Changes in weight, sucrose content, and purity of harvested roots during storage were measured for determination of gross sucrose and recoverable sucrose losses.

Treatment at a rate of 0.25 liter ethylene/m of travel reduced losses of weight, gross sucrose, and recoverable sucrose 31.2, 22.4, and 20.7%, respectively, during storage in 12 tests conducted in 1973, 1974, and 1975. The 0.50 liter/m ethylene treatment gave reductions in losses of weight, gross sucrose, and recoverable sucrose intermediate between those of the 0.25 liter/m and control treatments.

The 0.25 liter/m ethylene treatments reduced post‐harvest respiration and invert sugar accumulation which are primarily responsible for sucrose losses. The 0.50 liter/m ethylene treatment reduced respiration. Both treatments reduced the post‐harvest ethylene evolution of the roots.

Use of ethylene to reduce storage losses is limited by the lack of economic increase in sucrose yield per hectare at harvest.
Root Temperature and Percentage NO3−/NH4+ Effect on Tomato Development II. Nutrients Composition of Tomato Plants1
Authors: Ganmore‐Neumann Ruth , Kafkafi U.
Published: July 2010

The possibility of supplying nutrients daily to tomato plants (Lycopersicum esculentum Mill.) grown in various seasons raised the question of the best percentage NO3‐/ NH4+ to be supplied to these plants. The effect of four (8, 16, 24, and 34 C) temperatures and four percentage NO3‐/NH4+ (100/0, 75/25, 50/50, and 0/100) on the nutrient composition of tomato plants were studied. To obtain constant pH, percentage NO3‐/NH4+ and temperature continuous flow technique was used. The solution was flushed through the pots at a rate of 1 liter/hour.

Increasing root temperature increased total‐N, P, Mg, and K in the shoot irrespective of percentage NO3‐/ NH4+ in the solution. Calcium concentration increased in the shoot with increasing temperature only when the plants were fed with NO3‐ as the only source of N. The presence of NH4+> in the nutrient solution caused a decrease in Ca concentration in tomato plants grown in temperatures 16 C and above. Increase in the root temperature increased total‐N and Ca, slightly increased P, and decreased Mg and K. Increasing root temperature increased N‐N03‐ concentration in the shoot, while decreasing it in thc roots. Low root temperature caused accumulation of N‐NO3‐ and K in the roots. It is suggested that the hindering of translocation of these ions at low temperature is one of the factors that slows down growth of tomato plants fed with nutrient solution containing a high ratio of NO3‐.
Close‐Grown Tobacco: Agronomic Characteristics, Total Alkaloid, and Sugar Content1
Authors: Campbell C. R. , Chaplin J. F. , Johnson W. H. , Miner G. S.
Published: July 2010

The development of synthetic smoking materials has prompted researchers to consider non‐conventional production methods as a means of producing a low cost, flue‐cured tobacco (Nicotiana tabacum L.) material which might be used in the manufacture of cigarettes. In order to evaluate yield potential, chemical content, and physical characteristics of close‐grown tobacco, plants were grown in the field at populations of 45,448, 90,896, and 136,344/ha with different planting designs (twin or equidistant), nitrogen levels (84, 168, 252, and 336 kg/ha), and topping regimes (topping or no topping). The soil was a Durham loamy sand (fine loamy, siliceous, thermic, Typic Hapudult). The entire plant was flue‐cured and separated into lamina, midrib, and stalk for yield and chemical analysis. A wide range of yield, chemical content, and physical characteristics of the harvested material was produced by manipulating various cultural practices. Topped plants averaged 26% lamina, 12% midrib, and 62% stalk as compared to 19% lamina, 10% midrib, 54% stalk, and 17% top material for plants not topped. Yields increased progressively with N‐rate through 252 kg/ha and/or increased plant population. Twin or equidistant row spacing had no effect on yield. Topping decreased whole‐plant yield but increased the concentration of alkaloids and reducing sugars and the lamina: stalk ratio. Total alkaloids ranged from 0.18% for wholeplant nontopped tobacco receiving 84 kg N/ha to 0.84% for topped plants receiving 336 kg N/ha. Total reducing sugars averaged 8.0 for nontopped and 9.6% for topped plants.

Results indicate that high yields can be obtained by utilizing the close‐grown production system and harvesting the entire plant. Desirable chemical content and physical characteristics of close‐grown tobacco might be obtained by manipulating cultural practices.
Growth of Trickle‐Irrigated Tomato as Related to Rooting Volume and Uptake of N and Water1
Authors: Bar‐Yosef B. , Stammers Claire , Sagiv B.
Published: July 2010

Information about responses of plants in general, and of tomato (Lycopersicum esculentum Mill.) in particular, to various trickle‐irrigated soil volumes is meager. This information is essential in planning water rates and geometries and in scheduling drip irrigation systems.

Our objective was to study root development and distribution in a sandy soil in the field under three trickle irrigation regimes; yields, dry matter production, water and N content in the root zone and N uptake by the tomato were all evaluated in relation to root development.

Irrigation frequency increases from one to three irrigations per day produced a significant increase in dry matter yield, but decreased fresh fruit yield. A seasonal application of 620 mm compared to 320 mm, both applied as one irrigation per day, did not increase dry fruit yield, but increased fresh fruit yield by a factor of 1.46.

The main factor that contributed to the different response of the plants to the irrigation treatments, was the root weight and distribution in the soil during the growth period. In the once‐a‐day irrigation treatments, the root weight declined at the time of fruit filling, which caused a delay in production, while when irrigating three times a day, that decrease was not observed, and fruit dry matter production occurred at a higher rate. This response produced a greater final dry matter yield. In all the treatments the rapid fruit filling period was followed by a 55‐day period of slow dry matter production, which, in turn, was followed by an enhanced production rate.
Soil Temperature Effects on Winter Wheat and Winter Barley Emergence in the Field1
Authors: Russelle M. P. , Bolton F. E.
Published: July 2010

In the Pacific Northwest, potential yield and erosion control are affected by time of stand establishment of winter cereals. The objectives of this study were: 1) to investigate the effect of soil temperature on the rate of first and 70% emergence of winter wheat (Triticum aestivum L.) and winter barley (Hordeum vulgare L.) in the field; and, 2) develop a means of predicting the average effect of planting date on emergence at one location in eastern Oregon.

Two depths of soil mulch on stubble‐ and bare‐fallowed field plots were used to investigate the effect they have on soil temperature and on rates of first and 70% emergence. The soil was a Walla Walla silt loam (mixed, mesic Typic Haploxeroll). McDermid wheat was planted at biweekly intervals from August to November 1976 and 1977. Hudson barley was planted at similar intervals in the fall of 1976. Seeds were placed in moist soil with a deep furrow drill. Average soil temperatures were 0.5‐2.0 C higher at 10 cm under the bare‐fallow than under the stubble‐fallow treatments, but tillage did not affect emergence rate.

Regression equations of emergence rate and average 10‐cm soil temperature at a nearby U.S. Weather Bureau shelter were highly significant. The equations indicated that wheat required 149 and 210 degree days above a minimum of 0.7 and 0.4 C to obtain first and 70% emergence, respectively. Barley required 92 and 159 degree days above a minimum of 6.1 and 3.5 C for first and 70% emergence, respectively. A graph of 15‐year average daily 10‐cm temperature from 1 August through 30 November at Moro, Ore., was used with the equation to predict: 1) the average last date of planting to obtain emergence within a specified time period; and 2) the average length of time needed for emergence when the crops are planted on a given date. The average latest time to plant and obtain 70% emergence within 14 days is the last week of September.
A Screen‐Caged Thermocouple Psychrometer and Calibration Chamber for Measurements of Plant and Soil Water Potential
Authors: Brown Ray W. , Collins James M.
Published: July 2010

Estimates of water potential with thermocouple psychrometers are subject to errors due to temperature gradients. The objective here is to describe the design and construction procedures of a new screen‐cage single‐junction psychrometer that minimize these errors. The screen‐cage design restricts entry of contaminants into the psychrometer cavity; allows rapid vapor equilibration between the sample and the psychrometer; and provides a 360° concentric evaporation surface that reduces the influence of vapor condensation due to temperature gradients. In addition, a calibration chamber that can also be used for plant and soil samples is described.
Water Relations of Atriplex canescens as Affected by the Salinity and Moisture Percentage of Processed Oil Shale1
Authors: Richardson Steven G. , McKell C. M.
Published: July 2010

Osmotic adjustment through ion uptake is believed to be an important plant mechanism for ameliorating osmotic stresses imposed by high salt concentrations in the soil solution. Differential growth responses of plants to various salts may be due at least in part, to differences in osmotic adjustment because of differential ion uptake. A greenhouse study was conducted to determine whether differences in growth of fourwing saltbush (Atriplex canescens) in response to Na2SO4 and MgSO4, the two major salts in processed oil shale, might be due to differences in the effects of the salts on osmotic adjustment or other aspects of plant water relations. Magnesium sulfate was more detrimental to the growth of Atriplex canescens than was Na2SO4 when added at equal osmotic concentrations to leached processed oil shale. Cation concentrations in leaves were greater in response to Na2SO2 than to MgSO2. However, the osmotic and turgor potentials, determined from pressure‐volume curves developed with a pressure bomb and analytical balance, indicated that no differences in osmotic adjustment occurred due to chemical composition of the added salts. Osmotic adjustment did occur in response to reduced moisture percentage of the processed oil shale. Differences in leaf diffusive resistance indicated that water stress was greater in MgSO4‐treated plants than Na2SO4‐treated plants. Leaf size and succulence weregreater on Na2SO4‐treated plants than MgSO4‐treated plants.
Forage Quality Evaluation of Two Warm−Season Range Grasses Using Laboratory and Animal Measurements1
Authors: Griffin J. L. , Wangsness P. J. , Jung G. A.
Published: July 2010

The shortage of available forage during mid−summer is considered a major factor limiting the size of beef cowcalf herds in the Northeast. Consequently, using warmseason perennial range grasses as a supplement to existing cool−season grass forage programs is being considered. Animal feeding trials were conducted to assess the forage quality of ‘NY 1145’ big bluestem (Andropogon gerardi Vitman), and ‘Blackwell’ switchgrass (Panicum virgatum L.) grown in Pennsylvania. Laboratory and animal estimates of digestibility were compared.

Warm−season grass hays harvested at early head emergence, 2 weeks later, and at a regrowth stage in fall were fed with protein supplement to growing wether sheep in the first trial. In vivo digestible dry matter (DDM) of the hays ranged from 67 to 74%. Big bluestem and switchgrass DDM decreased 0.50 and 0.36 percentage units/ day, respectively, when harvest was delayed 2 weeks after head emergence, but dry matter intake (DMI) was not affected. Warm−season grass DDM and DMI were equal or superior to those for summer or fall harvested ‘Ky 31’ tall fescue (Festuca arundinacea Schreb.). In the second trial, DDM of big bluestem and switchgrass hays harvested at early head emergence and fed to mature wether sheep without protein supplement ranged from 56 to 69%. Digestible dry matter and DMI for the warm−season grasses were generally lower than those for tall fescue harvested in spring at the same growth stage.

In both animal studies, rankings of the grass hays using in vitro dry matter digestibility (IVDMD) and DDM estimates did not differ. The IVDMD technique did underestimate DDM by approximately 17 percentage units. This emphasizes the importance of animal evaluation in supporting laboratory forage quality analyses. Results suggest that big bluestem and switchgrass forage, harvested at early head emergence or later, appear most suitable for animals with lower nutrient requirements, such as beef cows.
Prediction of Daily Green Leaf Area Index for Corn1
Authors: Dale Robert F. , Coelho Dirceu T. , Gallo Kevin P.
Published: July 2010

Growth and duration of green leaf area of a crop determines the percentage of incident solar radiation intercepted by the crop canopy and thereby influences canopy photosynthesis, evapotranspiration, and final yields. The objective of this study was to develop a method for predicting the green leaf area index (LAI) for corn (Zea mays L.) on a daily basis through the growing season. Weekly measurements of the green leaf area (LA) of full‐season corn hybrids planted on one date in 1968 and two dates from 1969 to 1974 at the Purdue University Agronomy Farm, West Lafayette, Indiana, and air temperatures from the adjacent weather station were used to develop the model. A seasonal LAI curve was divided into three phenological periods, based upon the summation of a temperature function from date of planting to day t, ΣFTt. The LAIt during the first period (planting to silking) was described as a logistic function of population and ΣFTt, during the second period (silking to rapid senescence) by a linear regression of LAIt on population and ΣFTt, and during the third period (rapid senescence) by a linear regression of LAIt on the number of days past a ΣFTt threshold.

LAI curves were predicted for, and tested against, independent LAI measurements. The predicted curves compard well with the LAI measurements when used on nonstressed full season hybrids similar to those from which the equations were developed.
Bermudagrass for Forage in the Central U. S. Transitional Climatic Zone1
Authors: Faix J. J. , Kaiser C. J. , Hinds F. C.
Published: July 2010

Tall fescue (Festuca arundinacea Schreb.) is adapted to and is grown widely throughout the central US transitional climatic zone, a zone extending from south central Missouri across southern Illinois and eastward. Productivity and forage quality of fescue are favorable in early spring and fall but commonly decline to low levels during the summer. Improved bermudagrass may have potential to supplement tall fescue in the summer in this zone. New cold‐hardy, high yielding, more digestible bermudagrasses developed in Georgia and Oklahoma breeding programs may be suitable for more northern areas.

Experimental hybrids developed in the above programs and certain ecotypes were evaluated from 1974 through 1979 on a fine‐silty, mixed, mesic Type Fragiudalf soil in southern Illinois at the Dixon Springs Agricultural Center, 37° 26’ N, 88° 40’ W. Under 4 to 6 week harvest intervals, 11 of 17 bermudagrass entries yielded an average of 8.34 to 13.46 metric tons/ha dry matter annually. Georgia hybrids 72‐44 (now ‘Tifton 44’) and 72‐45 provided high yield, good seasonal yield distribution, and were undamaged by winter cold from 1974 to 1977. However, after two subsequent hard winters, spring recovery was markedly delayed. Early spring growth of ‘Hardie’ and ‘Midland’ was always vigorous but summer production of these cultivars was often decreased by leaf disease.

Average in vitro digestibility (IVD) for the bermudagrasses ranged from 43.8 to 50.6% and crude protein (CP) 11.0 to 13.8% from 1975 through 1977. Differences between entries for IVD and CP were small. It is concluded that bermudagrass such as Tifton 44 and hybrid 72‐45 which were resistant to leaf disease could improve summer forage production in the transitional climatic zone of the USA. However, spring removery of these lines may be retarded following abnormally hard winters.
Tolerances of Triticale Lines to Manganese in Soil and Nutrient Solution1
Authors: Mugwira L. M. , Floyd M. , Patel S. U.
Published: July 2010

High Mn in acid soils is sometimes toxic to plants. The Mn tolerance of triticale lines has not been established. The objective of this study was to determine the relative sensitivities of triticale (X Triticosecale, Wittmack) lines from the Alabama germplasm grown on high Mn soil and in nutrient solution. Twenty‐eight lines were grown on an Mn‐toxic Greenville sandy loam (Typic Hapludult) at pH 4.7 and 5.8 (Experiment 1). Lines ‘AM 2149’, ‘AM 3384’, ‘6TA 131’, and ‘6TA 203’ which showed differential responses to lime in Experiment 1 were grown on the same soil limed to pH values of 4.7, 4.9, 5.2, 5.5, 5.8, and 6.1 (Experiment 2). The same lines were grown in 1/5‐strength Steinberg solution with 2, 4, 8, 16, and 32 ppm Mn added (Experiment 3) and adjusted daily to pH 4.6. The relative top growth on the soil (pH 4.7/pH 5.8) varied between 24 and 98% for AM 3384 and AM 2149, respectively. The relative growth in nutrient solution with 32 ppm Mn ranged between 33 and 84%, respectively for AM 3384 and 6TA 131.

However, most of the cultivars had similar responses. The highest growth was obtained at pH 6.1 for the four cultivars tested (Experiment 2). The Mn concentrations in plant tops in the unlimed soil were not correlated to Mn sensitivities of the triticales. Nutrient solution studies indicated that 16 and 32 ppm Mn reduced plant growth when compared with lower Mn concentrations. Manganese tolerance rankings of cultivars were similar in soil and nutrient solutions. These data indicate that triticale lines can be selected for differential tolerance to Mn.
Effect of Temperature on Soybean Growth and Manganese Accumulation1
Authors: Ghazali N. J. , Cox F. R.
Published: July 2010

Manganese deficiency in soybeans (Glycine max (L.) Merr.) appears to be more severe in spring than in summer. This may result from a decrease in the Mn supply relative to growth or an increase in the functional requirement of Mn under cooler conditions. To examine the supply‐functional concentration relationship, experiments were conducted in growth chambers at various temperatures. Manganese deficient soybeans were exposed to various concentrations of Mn in nutrient solution and sampled periodically during vegetative growth. Both Mn accumulation and the growth parameters such as dry weight of plant parts, leaf area, and plant height increased exponentially with time. Since the growth parameters responded similarly, the results were expressed as the dry weight of the tops. The relative growth rate (RGR) and relative accumulation rate of Mn (RAR) were calculated. The RGR increased with both increasing temperature and Mn supply whereas the RAR increased primarily with increasing Mn supply. The RGR maximized between 10 and 20 ppb Mn in solution, indicating an adequate plant Mn concentration. At adequate Mn, the RGR increased from 0.08 to 0.12 g g−1 day−1 with increasing temperature and plant Mn increased with the Mn concentration in the nutrient solution. At inadequate Mn, the RGR increased with the Mn concentration in the nutrient solution and plant Mn equilibrated at a minimal concentration the functional requirement that decreased linearly from 7 to 4 µg/g with increasing temperature. Relative growth rate was then expressed as a function of plant Mn concentration and temperature. At higher temperatures, the functional requirement, of Mn was low but on increasing the top Mn concentration, the RGR plateaued at a high rate. On the other hand, at lower temperatures the functional requirement was greater and the RGR with adequate Mn was lower. At the functional requirement, the RGR was governed by the rate of Mn accumulation.
Tall Fescue and Smooth Bromegrass. I. Nitrogen and Water Requirements1
Authors: Eck H. V. , Martinez Tito , Wilson G. C.
Published: July 2010

Irrigated cool‐season grasses are needed in the Southern High Plains to extend grazing provided by winter wheat (Triticum aestivum L.) pasture and native range. Little information is available concerning their N requirements in relation to irrigation water application. The main objective of this study was to determine the N and water requirements for sustained high production of tall fescue (Festuca arundinacea Schreb.) and smooth bromegrass (Bromus inermis Leyss.). ‘Fawn’ tall fescue and ‘Southland’ smooth bromegrass were grown on Pullman clay loam (fine mixed thermic, Torrertic Paleustoll) under fertilizer N rates of 0, 168, 336, 504, and 672 kg ha‐1year‐1 on three water regimes. The N source was NH4NO3 except in a companion study in which feedlot manure was used.

In one year of the 3‐year study when all irrigation treatments could be compared, adequately watered (W‐2) and fertilized (672 kg N/ha) tall fescue yielded 15.2 metric tons/ha, whereas similarly treated smooth bromegrass yielded 12.0 metric tons/ha. With moderate water (W‐I) and adequate N, however, smooth bromegrass yielded 6.9 and tall fescue yielded 5.2 metric tons/ha. With moderate water distributed for cool‐season forage production (W‐3), respective yields of similarly fertilized tall fescue and smooth bromegrass were 11.9 and 10.9 metric tons/ha. Also in 1976, first cuttings produced 77, 62, and 82% of total seasonal yields on W‐l, W‐2, and W‐3 plots, respectively.

Over the 3‐year period, yield increases were almost directly proportional to the amount of N applied through 336 kg/ha. Yield increases per kg of applied N (to 336 kg/ha) were 12.1, 24.1, and 17.9 kg on W‐l, W‐2, and W‐3 plots, respectively. Feedlot waste, at N rates equivalent to those applied as‐ NH4NO3, was about one‐half as efficient as NH4NO3 in increasing yields.

In the Southern High Plains, the most efficient irrigation management for tall fescue and smooth bromegrass is for early spring production with subsistence irrigation for the rest of the year.
Leaf Azimuthal Orientation of Sorghum in Four Row Directions1
Authors: Lugg D. G. , Youngman V. E. , Hinze Greg
Published: July 2010

The objective of this study was to determine if the leaf azimuthal orientation of grain sorghum (Sorghum bicolor (L.) Moench) was at random. Plants were grown in each of four row directions, North‐South (N‐S), Northeast‐ Southwest (NE‐SW), East‐West (E‐W), and Northwest‐ Southeast (NW‐SE). In 1972, from 8 to 16 August, there was a strong bimodal azimuthal orientation which was either east‐west or perpendicular to the rows. In addition, there was a significantly larger proportion of leaves to the south of the east‐west axis than to the north. In 1973, three readings were taken: 17 or 18 July, 2 or 3 August, and 29 or 30 August. On the earliest sampling, a significant proportion of leaves faced west rather than east. Orientation was altered with the emergence of the flag leaves, of which 60% faced east. We concluded that leaf orientation was not distributed randomly either year.
Screening Sorghum for Aluminum Tolerance in Nutrient Solutions1
Authors: Furlani P. R. , Clark R. B.
Published: July 2010

Identification of Al tolerant sorghum [Sorghum bicolor (L.) Moench] is important if this crop is to be grown successfully on acid, Al‐toxic soils. A rapid method for screening genotypes for Al tolerance was developed by growing over 100 plants in the same container of relatively small volume (50 ml/plant). Mineral element conditions that gave good differential responses for Al tolerance were 148 µmol liter−1 Al, 64 µmol liter−1 P, 7.4 mmol liter−1 Ca, 1.6 mmol liter−1 Mg, 3.9 mmol liter−1 K, 24.7 mmol liter−1 N (8 NO3−:1 NH4+), light (17 hours)/dark (7 hours) temperatures of 28/23 C, and solution pH values below 4.0. Mineral element levels or temperatures higher or lower than these resulted in poorer differential responses of genotypes to Al, either because Al had essentially no effect or Al effects were too severe. Nitrate as a single N source could not be used to screen for Al tolerance because the solution pH increased as plants grew and Al in solution was inactivated. A mixture of NO3− or NH4+ gave better genotypic separation than NO3− or NH4+ alone. Visual Al toxicity symptoms on roots were noted within 10 days, and seminal root lengths could be used to assess Al tolerance of sorghum genotypes. Differences in root and top dry matter yields did not distinguish sorghum genotypes for Al tolerance.
Subtropical Grass Species Response to Different Irrigation and Harvest Regimes1
Authors: Mislevy P. , Everett P. H.
Published: July 2010

Perennial grasses can be grown in subtropical areas of the world having little frost damage, but, in many areas low temperatures (1 to 10 C) at higher elevations and lack of moisture may restrict growth of most subtropical forages and create critical feed shortages for livestock. A study of the seasonal distribution of forage production of subtropical grasses was conducted to determine production and quality and to develop improved management practices. Sixteen grasses (four Cynodons, three Paspalums, eight Digitarias, and one Brachiaria) were grown with and without irrigation and harvested at two stubble heights (5 and 10 cm) at 30‐day intervals for 30 consecutive months (March 1973 through August 1975). The experiment was conducted at the Immokalee Research Center in south Florida on a sandy siliceous, hyperthermic, Arenic Haplaquod (Immokalee fine sand) soil. Winter forage production (October through March) was highest for Cynodon spp (27% of total annual yield) and lowest for Paspalum spp. (14% of total annual yield). Plants cut at a 5‐cm stubble initially outyielded plants harvested at 10 cm. However, after 2.5 years little difference was observed in dry matter yield between stubble heights, except for the Paspalum spp. and Brachiaria sp. which continued to produce more forage at the 5‐cm stubble height. Little difference was observed in percentage crude protein and IVOMD between grass entries harvested during the summer growth period with the exception of Brachiaria which was significantly higher in IVOMD. Both crude protein and IVOMD were much lower in forage harvested during the summer than the winter for all grasses, again with the exception of the IVOMD for Brachiaria which had a summer‐winter range of 58 to 64%. This entry was one of the highest in dry matter yield, crude protein, and IVOMD percentage, but produced 83% of its dry matter during the summer. Irrigation had little effect on dry matter production at any season. Higher IVOMD was obtained from cut short with no irrigation. These data indicated that Cynodons harvested at a 5‐cm stubble produced highest dry matter production during the cool winter season, containing high crude protein and IVOMD levels. Dry matter yields in summer were 200 to 300% higher than in winter, however, forage quality was much lower during the summer.
Manganese Effects on Yield and Nutrient Concentration in Leaves and Seed of Soybean Cultivars1
Authors: Parker M. B. , Boswell F. C. , Ohki K. , Shuman L. M. , Wilson D. O.
Published: July 2010

Critical and sufficiency concentrations of Mn in soybean [Glycine max (L.) Merr.] leaves are levels which are deficient and adequate, respectively. These levels have been determined with a single cultivar. However, since several cultivars are often grown in Mn deficient areas, it becomes important to know if cultivars have different Mn requirements.

A 3‐year study was conducted on an Olustee‐Leefield sand (Ultic Haplaquads — Arenic Plinthaquic Paleudults) near Tifton, Georgia to evaluate Mn treatments on soil test values, on nutrient concentration in leaves and seed, and on seed yields of eight soybean cultivars.

The addition of Mn increased the amount of Mn extracted from the soil each year by the double acid (0.05 N HCl + 0.025 N H2SO4) and DTPA (diethylenetriaminepentaacetic acid) solutions, but double acid extracted considerably more Mn than did DTPA. Significant differences in yield, concentration of Mn in tissue, and seed weight among cultivars from Mn application were obtained only in the third year (1977) when the soil pH was increased to 7.0. The addition of Mn to the soil increased leaf Mn in all cultivars and seed Mn and seed yields in five of eight cultivars. Concentrations of Mn in recently matured leaves (R2 stage) varied among cultivars in untreated plots from 10 to 17 ppm and in Mn treated plots from 20 to 28 ppm. Seed Mn varied from 8 to 14 ppm in untreated plots and 13 to 20 ppm in Mn treated plots. Average seed yield (across cultivars) in the third year was increased 5.3 quintals/ha or 27% by Mn over no Mn with more than one‐third of the yield increase attributed to increased seed weight. Nutrients, other than Mn, in plant tissue were not affected by Mn treatments; however, small differences occurred among cultivars in concentration of P, K, Ca, Mg, Cu, Fe, and Zn in leaves and seeds.

A regression equation indicated that the average critical and sufficiency levels of leaf Mn for eight soybean cultivars were 18 and 29 ppm, respectively. Our data suggest that several cultivars should be used to establish critical or sufficiency values for leaf Mn in order to develop an adequate range in values for the number of cultivars usually grown in Mn deficient areas.
Techniques for Thermocouple Placement and the Automation of Temperature Measurements in the Microenvironment of Kentucky Bluegrass1
Authors: Welterlen M. S. , Watschke T. L.
Published: July 2010

A Kentucky bluegrass (Poa pratensis L.) sward is comprised of many closely spaced, minute plants forming a dense, low canopy. Measurements of soil and basal tiller temperatures require careful placement of many small sensors. The objectives of this research were to develop expedient methods for obtaining precise point measurements of tiller, thatch, and soil temperatures with thermocouples in the field. Measurements were made in ‘Touchdown’ Kentucky bluegrass mowed to 5 cm.

Throughout the study, Chromel‐Alumel thermocouples were used. A 40‐channel, microprocessor‐based data acquisition system and a computer compatible nine‐track magnetic tape were used for uninterrupted data collection. Irradiance, measured approximately 1 km from the experimental site, and air temperature, sensed by an aspirated thermocouple located 1.5 m above the turf, were recorded simultaneous with sod temperature measurements.

Thermocouples [20 AWG (0.81 mm)] placed horizontally and vertically, thermocouples [40 AWG (0.076 mm)] placed vertically, and thermocouples [40 AWG] fastened to 0.6 cm diameter wooden dowels were placed 2 cm below the thatch‐soil interface and compared for precision and placement expedience. Vertically placed fine‐gauged thermocouples (the most expedient means of installation) were as precise as the other methods. Although gauge did not influence precision in this test, in some situations (particularly vertical placement) the potential for error may exist due to heat flow along the wire.

Two methods of thermocouple (40 AWG) placement into basal tillers were compared for expedience of placement and relative precision. In one method, thermocouples were threaded through the tiller base leaving the thermocouple bead inside the tiller with lead wire connection on opposite sides. The other method involved direct insertion into a hypodermic puncture in the tiller base. The inserted thermocouple method was found to be the most expedient, and no significant temperature differences were found between the methods. Tiller base temperatures measured in the field on a cloudy afternoon on 11 June 1979 ranged from 16.8 to 21.1 C, with a maximum difference of 0.6 C between the two methods (insignificant at the 0.05 level). The coefficients of variation for each method were not greater than 10.6. Temperatures measured during a clear afternoon on 12 June 1979 ranged from 23.1 to 31.5 C. At 1500 hours, the difference between the methods of placement was greatest (3.3 C) but was not significant at 0.05. The maximum coefficient of variation was 15.3 and 13.7 for the inserted and threaded thermocouples, respectively. Throughout the day, the threaded method had generally lower coefficients of variation.
Growth Analysis of Maize Hybrids Differing in Photosynthetic Capability1
Authors: Gaskel M. L. , Pearce R. B.
Published: July 2010

There is, theoretically, a close association between leaf photosynthesis and dry matter production. However, many factors affect plant productivity and photosynthesis under field conditions which are not measured with leaf photosynthesis in the laboratory. Studies were undertaken to determine if there are patterns of leaf area development or dry matter accumulation in maize (Zea mays L.) plants that may interfere with a leaf‐photosynthesis, plant‐productivity relationship.

Six experimental maize hybrids were selected for detailed growth analysis during vegetative development. Three of these hybrids had previously exhibited higher CO2 exchange rates (CER) and three had exhibited lower CER. Plants were sown in the field in early May and early June to obtain densities of 5.3 plants/m2 during the 1978 and 1979 growing seasons. The soil was a Clarion (Typic Hapludoll, fine‐loamy, mixed mesic) soil. Leaf CER of excised blades, leaf blade area on main culms and tillers, and dry weight of main culms and tillers were measured weekly through 6 weeks of growth.

The hybrids maintained the CER status for which they were selected during all growth periods. High‐CER hybrids tillered more profusely than did low‐CER hybrids. Overall leaf area was greater in high‐CER hybrids, primarily due to greater tillering. Dry weight of main culms and tillers among hybrids generally followed leaf area distribution. Dry weight accumulation patterns between main culm and tillers during late vegetative development suggested that high‐CER hybrids exported “excess” main culm assimilates to nonproductive tillers or belowground sinks. This phenomenon, if real, would affect any yield advantage attributable to high CER capability.
Subsurface Irrigation and Fertilization of Field Corn1
Authors: Mitchell W. H.
Published: July 2010

Trickle irrigation is a rapidly developing technology with high potential for water and energy conservation. Surface placement of emitter lines is typical of current installations. The lines interfere with cultural operations leading to costly annual replacement and limiting its use to high value crops. The objective of this experiment was to determine if deeply placed emitter lines could be used to effectively deliver water and anhydrous ammonia (AA) to the sub‐tillage root zone of field corn (Zea mays L.) in the presence of several broadcast N, P, K treatments.

Field corn was grown on Matapeake silt loam (fine silty, mixed mesic Typic Hapludult) and subsurface irrigated during the period 1973 to 1979. Emitter lines were placed 90 cm apart at a depth of 36 cm. Irrigation treatments included no irrigation, subsurface irrigation (SSI), and SSI plus AA. Broadcast N, P, K was applied annually at 0, ½, 1, 2, and 3 time rates with the 1 time rate equal to 112,25, and 94 kg/ha of N, P, K, respectively. Annual treatments with N, P, K were made from 1965 to 1973 but following 1973 P and K treatments were discontinued although N applications were repeated annually through 1979.

Anhydrous ammonia applied through the SSI system increased N use efficiency when compared to broadcast ammonium nitrate. When AA was injected through the SSI system no benefit was derived from broadcast‐N applications. Phosphorus and K availability, as measured by ear leaf analysis, was increased when AA was injected through SSI. The application of AA through SSI depressed soil pH but the effect was localized within a 10 to 12‐cm radius of the emitter lines. Corn roots concentrated in soil adjacent to emitter lines causing an increase in organic matter that appeared to stabilize emitter line flow rates. It was concluded that a properly installed SSI system can have a functional life of at least 7 years.
Quality Estimates and Chemical Characterization of Fermented and Unfermented Summer Annual Forages1
Authors: Burns J. C. , Kimbrough E. L.
Published: July 2010

Livestock enterprises require forage crops that provide feed during or after midsummer. Ten cultivars representative of forage and grain sorghums [Sorghum bicolor (L.) Moench], sorghum ✕ sudangrass (Sorghum vulgare sudanense) hybrids, and millet [Pennisetum americanum (L.) Leeke] that provide forage during this time of the year were evaluated for quality and fermentation characteristics. Chemical and bioassay measurements were compared prior to and after fermentation.

Fermentation patterns were altered by sample handling. Expulsion of air from plastic fermentation bags by simply hand pressing or removal or air in the field by vacuum produced satisfactory silage for experimental purposes. Additional handling in the laboratory to heat seal was undesirable as it significantly increased pH and lactic acid concentrations and reduced titratable acidity.

Fermentation generally reduced differences in IVDMD among cultivars within major types in the unfermented forage. Both N and crude fiber (CF) concentrations in oven‐dried samples generally were higher in fermented than in unfermented forage, but no difference was noted between 45 and 90 days of fermentation. Water‐soluble carbohydrate (WSC) levels were significantly altered by the drying method and fermentation. The WSC levels for unfermented forage and that fermented 45 and 90 days were 16.7, 6.6, and 7.6%, respectively. The WSC levels averaged 19.8% in unfermented freeze‐dried forage and 13.7% in unfermented oven‐dried forage. The WSC levels for fermented freeze‐dried forage were similar to those for oven‐dried forage (7.5 vs. 6.7%). The WSC percentages in the freeze‐dried, unfermented forage was not significantly correlated with either acetic or lactic acid production in 45‐day freeze‐dried fermented forage (r = 0.67 and 0.54, respectively), but were significantly correlated with titratable acidity (r = 0.93**). There was no indication of improved quality in fermented forage for which the WSC concentration was high in the unfermented tissue. Total digestible nutrients (TDN), computed from CF, averaged 58.2, 57.0, and 56.9% for the oven‐dried unfermented and 45 and 90‐day fermented silages, respectively, compared with IVDMD percentages of 52.6, 45.1, and 46.0.
Sod‐Seeding Forage Legumes in a Tall Fescue Sward1
Authors: Olsen F. J. , Jones J. H. , Patterson J. J.
Published: July 2010

Introduction of forage legumes into tall fescue (Festuca arundinacea Schreb.) swards by sod‐seeding may greatly enhance herbage production. This study was undertaken to determine the establishment and productivity of selected legumes sod‐seeded in tall fescue and to assess the effectiveness of selected chemicals for the temporary suppression of grass foliage. This work was conducted in southern Illinois on a Stoy soil (fine‐silty, mixed, mesic Aquic Hapludalf). Five forage legume species, alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), crownvetch (Coronilla varia L.), ladino clover (Trifolium repens L.), and red clover (Trifolium pratense L.), were sod‐seeded in tall fescue with the Allis‐Chalmers No‐Till planter and the Zip sod‐seeding drill. Selected alfalfa and red clover cultivars were evaluated and the effectiveness of four chemicals at three different rates for temporary suppression of the tall fescue top growth was also assessed.

All forage legumes except crownvetch were established successfully by sod‐seeding. The introduced legumes enhanced the total overall dry matter yields of the tall fescue sward by up to three times under hay production management. Alfalfa was the most productive and long‐lived sod‐seeded legume. Red clover and ladino clover appeared to be well suited legumes for sod‐seeding for short‐term stands. There were no notable differences in herbage production among alfalfa cultivars evaluated, but there were differences among red clover cultivars the 3rd year. The red clover cvs. ‘Kenstar’ and ‘Florie’ persisted for three growing seasons. Glyphosate [N‐(phosphonomethyl) glycine] and paraquat (1,1'‐dimethyl‐4, 4'‐bipryidinium ion) both suppressed tall fescue topgrowth for an adequate period of time for successful legume establishment by sod‐seeding. Acceptable forage legume stands were obtained with the Allis Chalmers No‐Till planter and Zip seeder under proper soil moisture and plant cover conditions.