bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of the Soil and Plant Water Potentials on the Dry Matter Production of Snap Beans1
Authors: Millar A. A. , Gardner W. R.
Published: July 2010

The need for greater plant yields and more efficient use of water makes it essential that the relations between soil‐water content, soil‐water potential, transpiration rate, and plant response be made ever more quantitative.

The dry matter production rate of snap beans (Phaseolus vulgaris L., var. Bush Blue Lake) growing under field conditions on a sandy soil is analyzed during a drying period.

Measurements of plant‐ and soil‐water potentials, dry matter accumulation, and stomatal resistance were made as soil‐water was depleted, while the transpiration rates were obtained by a model for a loosely structured canopy.

The transpiration and dry matter production rates decreased curvilinearly with soil‐water potential. When the soil‐water potential decreased from −0.28 to −0.40 bar, there was 47% reduction in the dry matter production rate. This is related to the turgor pressure‐operated stomatal mechanism. The adaxial stomatal resistances increased at leaf‐water potentials lower than −8 bars, which coincided with a rapid decrease in the dry matter production rate. It was found that stomatal closure due to water stress resulted in a greater reduction of growth rate than in transpiration.
Effect of Soil pH on Element Concentration and Uptake by Maize: II. Cu, B, Mn, Mo, Al, and Fe1
Authors: Lutz J. A. , Genter C. F. , Hawkins G. W.
Published: July 2010

An understanding of liming, fertilization, plant nutrition, and soil‐plant relationships requires a knowledge of the variability of element accumulation within the plant. The availability of micronutrients is related to soil pH. Except for Mo, the availability of micronutrients is believed to increase with increased acidity. Since many of the soils in the southeastern U. S. are acid, particularly the subsoil, additional information is needed on the growth, concentration, and uptake of elements by maize (Zea mays L.) as affected by soil pH.

Selected maize inbreds and single crosses were grown in the greenhouse on Greendale silt loam that had been adjusted to pH levels of 3.9, 5.1, and 6.1 with appropriate amounts of pulverized dolomitic limestone. Adequate plant nutrients were applied. Maize was harvested 36 days after planting; dried; and later analyzed for Cu, B, Zn, Mn, Mo, Al, and Fe.

Entries differed significantly in concentration of each analyzed element at one or more pH levels, thus showing differential absorption of specific elements at various pH levels. Soil pH had a highly significant effect on the concentration of all elements studied except Fe. The entry × pH interactions were significant only for B and Al concentrations.

Entries differed in the uptake of all elements studied. Uptake of all elements except B was affected by pH, and entry × pH interactions were significant for each of the elements considered.
Soil Management Factors and Growth of Zea mays L. on Topsoil and Exposed Subsoil1
Authors: Batchelder A. R. , Jones J. N.
Published: July 2010

Exposed subsoils frequently are infertile and have low available water storage capacities. Corn (Zea mays L.) was grown for 4 years on a Groseclose clay loam surface soil and exposed clay subsoil to study the effects of selected management practices on subsoil productivity and the available water storage in exposed subsoils. Half of the exposed subsoil plots were covered with straw mulch, and half of all plots were irrigated. Lime was added the first 2 years and fertilizer was added each year to alleviate the growth‐limiting effects of low pH and low fertility.

The treatments were reflected in surface water runoff from the 10 to 12% slopes, in soil water tension relation. ships, in plant growth, and in grain yields. Mulching reduced the surface water runoff, resulting in greater net water input. The soil water tensions to a depth of 45 on were generally lower under the straw mulch without irrigation than with either of the topsoil treatments.

Top growth and grain yields generally increased on the subsoil treatments each year, and in the 4th year yields from the irrigated subsoil without mulch and both the irrigated and nonirrigated subsoil with mulch were equivalent to those of the irrigated topsoil, and significantly greater than those of topsoil without irrigation. In the last 2 years, when soil tests indicated that the low pH and low fertility had been mitigated, relative yields were markedly affected by the number of days during which the soil water tension at the 45‐cm depth exceeded 700 mb.
Effect of Planting Date on Sunflower Yield, Oil, and Plant Characteristics1
Authors: Johnson B. J. , Jellum M. D.
Published: July 2010

Planting date studies were conducted on sunflowers (Helianthus annuus L.) from 1969 through 1971 at Experiment, Ga. to evaluate the optimum time of planting on seed yield, oil percentage, oil composition, and other plant characteristics. Seeds of ‘Peredovik’ and ‘Krasnodarets’ varieties were planted at each date ranging from March 11 to July, 22.

Highest seed yields and oil percentage of seeds were produced when sunflowers were planted from mid‐March through April. Fatty acid composition of seed oil varied considerably among planting dates within years as well as among similar planting dates between years. Other sunflower characteristics were not greatly affected except at the June or July plantings.
Phosphorus and Nitrate‐Nitrogen Immobilization by Wheat Straw1
Authors: Black A. L. , Reitz L. L.
Published: July 2010

With stubble‐mulch tillage systems, relatively large quantities of wheat straw with low N and P concentrations are being incorporated near seeding time in inherently P‐deficient soils of the northern Great Plains. This study was conducted to determine what additional adjustments in fertilizer applications might be necessary to compensate for the amount of N and P immobilized by known quantities of incorporated wheat straw under defined soil fertility levels.

Wheat straw was incubated with four soils—Tally loamy sand, Dooley sandy loam, Williams clay loam, and Cherry silty clay. Straw was added at rates up to 10,000 ppm; and P, up to 260 ppm. The experiment was a randomized complete factorial design with three replications for soils, P rates, and straw rates. NaHCO3‐soluble P and nitrates were determined after seven alternate wet and dry incubation periods during a 60‐day period.

Soluble P increased progressively as rate of P applied increased. Soluble P decreased progressively (P=.05) as straw rates increased. In all four soils, straw incorporation caused a much larger proportional decrease of soluble P at low than at high levels of applied P. The soil by straw treatment interaction was not significant (P=.05), indicating that incorporated straw rates had the same effect on soluble P in all soils. Soil nitrate mineralization was not significantly influenced (P=.05) by P rates even though the soils were P deficient. Nitrate levels decreased significantly as straw increased.
A Miniature Gravity‐Fed Thermocouple Psychrometer1
Authors: Mitchell S. T. , Kimball B. A. , Ehrler W. L.
Published: July 2010

A miniature gravity‐fed thermocouple psychrometer was constructed and tested over a wide range of humidities and flow rates. The unit gave accurate wet bulb depression in 6‐mm flow tubes through an acrylic plastic block with a minimum flow rate of only 0.06 m/sec at 35% RH, and of only 0.09 m/sec at 11% RH.

The psychrometer also agreed exactly with a standard psychrcmeter (Assmann type) in open air without forced ventilation or radiation shielding.
Effects of Nitrogen on Leaf Area Index, Leaf Area Duration, Net Assimilation Rate, and Yield of Wheat1
Authors: Khalifa M. A.
Published: July 2010

The low returns from nitrogen fertilization in central and eastern Sudan stimulated an investigation into the response of grain yields of irrigated wheat (Triticum aestivum L. em. Thell.) to two sources of nitrogen (ammonium sulfate and urea), two methods (broadcasting and sidedressing), and several times of application. Grain yields were unaffected by either source of nitrogen or by method of application. Application of the fertilizer at different stages of growth showed that the addition of fertilizer in the early phases of growth of the crop (at sowing or tillering) gave the greatest response. The response to application at ear emergence was much less. Splitting the nitrogen amount with half given at sowing and half at tillering or ear emergence had no extra merit, and a second application given early in the growing season had more effect on yields than a later one at ear emergence. Growth analysis indicated that the variation in grain yield was mainly a reflection of the effect of the treatments on the leaf area duration (LAD) after ear emergence. Early nitrogen application effectively increased LAD by increasing the leaf area index (LAI) toward the time of ear emergence, while late nitrogen had very little effect on LAI and consequently on LAD after ear emergence.
Broadcast or Banded Atrazine + Propachlor with Tillage Variables in Grain Sorghum1
Authors: Moomaw R. S. , Robison L. R.
Published: July 2010

Application of a herbicide to the least possible soil surface area consistent with adequate weed control in a given crop production system may be desirable because costs are reduced and less chemical is added to the environment. Data have not been available to indicate the minimum herbicide band width that could be used in combination with mechanical tillage in grain sorghum [Sorghum bicolor (L.) Moench] production. The herbicide mixture 2‐chloro‐4(ethylamino)‐6‐(isopropylamino)‐s‐triazine (atrazine) + 2‐chloro‐N‐isopropylacetanilide (propachlor) was applied preemergence broadcast and in herbicide band widths of 18, 36, and 53‐cm to grain sorghum. All herbicide treatments were applied as 1.1 kg atrazine + 2.7 kg propachlor per treated hectare. One row‐middle cultivation and one rotary hoeing were also imposed on the herbicide treatments as variables. The 18‐cm band of atrazine + propachlor with supplementary row‐middle cultivation was as effective in controlling weed growth and maintaining grain yield as were wider herbicide bands or a broadcast treatment. Broadcast herbicidetreated sorghum without cultivation yielded as well as the handweeded treatment both years of the experiment. Cultivation reduced average weed growth 73%. Cultivator effectiveness on an 18‐cm herbicide band equalled that measured on wider herbicide bands. Rotary hoeing significantly reduced weed growth and increased average grain yields 10% on herbicide‐treated plots. The average ratio of weed dry weight to reduction in grain sorghum yield was 1.3 to 1.
Evaluation of Herbicides for Use in Zero and Minimized Tilled Corn and Sorghum1
Authors: Robison L. R. , Wittmuss H. D.
Published: July 2010

Adequate weed control has been one of the principal problems associated with developing minimized tillage systems. Recent herbicide releases appear promising for solving the weed control problem. We evaluated ten different preemergence herbicide treatments and one postemergence treatment for 3 years for weed control in till‐planted corn (Zea mays L.) and sorghum (Sorghum bicolor, L. Moench). All herbicide treatments were compared on plots that were either disked or nondisked to see if reduction of plant residues improved weed control. All herbicide treatments reduced weed populations and resulted in increased yields compared to the cultivated check. Plots that were disked as opposed to those nondisked were significantly lower in weed yields for 2 years, but were significantly better in crop yields only 1 year.

Most of the herbicides gave excellent weed control even though residues of the previous year's crop averaged 5,218 kg/ha and covered 73% of the ground.
Effect of Supplemental Water on Barley and Corn Production in a Subhumid Region1
Authors: Power J. F. , Bond J. J. , Sellner W. A. , Olson H. M.
Published: July 2010

A 3‐year field experiment was conducted on a loam soil in eastern North Dakota to determine the effect of supplemental water, added in various quantities and at different times, on malting barley (Hordeum vulgare, L.) and corn (Zea mays, L.) silage production. Irrigation consisted of (a) none; (b) after previous harvest only (to fill 120‐cm profile); (c) 6 cm applied per irrigation as needed during growing season; (d) after previous harvest plus 6 cm at anthesis; (e) after previous harvest plus 6 cm applied as needed during the growing season; and (f) after previous harvest plus 9 to 12 cm applied as needed during the growing season. Water added after harvest was not reflected in soil water content by seeding time the following spring or in increased crop yields, indicating that fall irrigation was of little value. A linear regression (r = 0.89) existed between total water use and both barley grain and corn silage production, with no distinct differences between the six water treatments evident. These results suggest that stored soil water, growing season precipitation, and added irrigation water are all equally effective in enhancing crop production, and within the range studied, one can be substituted for the other. The results also suggest that such factors as amount of water added per event and frequency or timing of events may be of less importance in subhumid than in more arid climates.
Manganese Nutrition of Cotton Under Two Boron Levels I. Growth and Development
Authors: Ohki Kenneth
Published: July 2010

Upland cotton (Gossypium hirsutum L.) plants were grown in nutrient solution under greenhouse conditions to study manganese × boron interaction on cotton growth and development. A 2 × II factorial experiment included added B at 35 and 500 /ig B/I with eleven Mn rates from O to 4000 μg added Mn/1.

The appearance of visible Mn deficiency symptoms preceded growth reduction indicating that growth rate processes are inhibited prior to visible deficiency manifestations. With very low Mn levels, only Mn deficiency symptoms existed at both B levels. As Mn levels increased slightly under low B, both B and Mn deficiency symptoms were simultaneously present, and at higher Mn levels where Mn supply was not limiting, only B deficiency symptoms occurred. Plant growth indicated by top weight was correlated with Mn and B deficiency symptoms.

Manganese and B deficiencies retarded internodal growth without adversely influencing nodal development. Both Mn and B deficiencies reduced square development. The node of first fruiting branch was not affected by either B or Mn rates indicating no response to crop earliness.
Preplant Application of Herbicides for Weed Control in Grain Sorghum1
Authors: Wiese Allen F. , Chenault E. Wayne , Hollingsworth Dale
Published: July 2010

At the time these studies were initiated, there was no effective, safe method of applying herbicides prior to planting sorghum (Sorghum bicolor (L.) Moench). Over a 4‐year period, preplant application of herbicides at various times before planting and methods of herbicide incorporation were evaluated for control of pigweed (Amaranthus spp.) and barnyardgrass (Echinochloa crusgalli:(L.) Beauv). Effective preplant herbicides on clay loam soil were terbutryn (2‐(tert‐butylamino)‐4‐(ethylamino)‐6‐(methylthio)‐s‐triazine), propazine (2‐chloro‐4,6‐bis(isopropylamino)‐s‐triazine), and mixtures of propazine with either norea (3‐hexahydro‐4,7‐methanoindan‐5‐yl)‐l,l‐dimethylurea) or linuron (3‐(3,4‐dichlorophenyl)‐l‐methoxy‐l‐methylurea). In order to prevent crop injury and obtain weed control equal to or better than that obtained with preemergence application, the herbicides had to be applied to beds and incorporated with a rolling cultivator within 2 weeks prior to planting. Incorporation with a tandem disk before bedding resulted in crop injury.
Portable Reflectance Meter for Estimating Chlorophyll Concentrations in Leaves1
Authors: Wallihan E. F.
Published: July 2010

The need to measure changes of chlorophyll concentration in citrus leaves required a nondestructive method of analysis applicable to field use. Light reflectance in the wavelength region of 600 nm had been shown to be useful for this purpose but existing reflectance meters were too bulky for field use and generally required line power. The instrument described here is battery operated, compact, and measures light reflectance in a band of wavelengths from 610 nm to 700 nm from four miniature incandescent lamps. Arrangement of the light unit on a spring clamp permits readings in the field on several leaves per minute.

Calibration against measured chlorophyll concentrations yields a log log curve revealing maximum sensitivity at low chlorophyll concentrations. Tests on leaves from iron‐deficient orange trees showed the coefficient of variability to be in the vicinity of ± 15%. By reading 20 replicate leaves, sampling errors were compensated sufficiently to give precision of about ± 3%.

Major limitations observed were (1) interference from red pigments in young leaves and (2) variable readings from mottled leaves, depending on position of the sensor on the leaf.
Effect of a Killed Sod Mulch on Nitrate Movement and Corn Yield1
Authors: Thomas G. W. , Blevins R. L. , Phillips R. E. , McMahon R. L.
Published: July 2010

Corn (Zea mays L.) was planted in a Maury silt loam soil under conventional tillage and in a chemically‐killed bluegrass (Poa pratensis L.) sod in 1970 and 1971 in order to determine the behavior of nitrate and the yield of corn under both cultural systems. Nitrate under both cultural treatments was sampled before and after June rainfall periods in both years. A large fraction of the nitrate was lost from the top 90 cm of soil under the killed‐sod plots, whereas, no nitrate was lost from the conventionally‐tilled plots. The loss of nitrate under the killed sod was attributed to two factors: 1) lower evaporation from the mulched soil; and 2) deep penetration of water and nitrate through larger pores in the wetter, mulched soil.

Corn yields where nitrogen was applied tended to be higher on the killed‐sod plots in a dry year (1970) and about the same in a wet year (1971). However, the no nitrogen treatment on the mulched plots had a much lower yield than did the conventionally‐tilled no nitrogen treatment in the wet year of 1971. The results suggest that higher nitrogen rates may be required when corn is grown in a killed sod mulch as compared to conventionally‐tilled corn.
Comparative Lime Effects on Continuous No‐Tillage and Conventionally Tilled Corn1
Authors: Moschler W. W. , Martens D. C. , Rich C. I. , Shear G. M.
Published: July 2010

Because the absence of tillage precludes the mixing of lime with soil when no‐tillage corn (Zea mays L.) is grown, an experiment was conducted to determine if surface application would be effective. Information on the subject is not presently available but is needed to guide growers in neutralizing soil acidity caused by high rates of nitrogen applied to corn.

Field studies over an 8‐year period compared continuous no‐tillage corn with surface‐applied lime to continuous conventionally tilled corn with lime incorporated into the soil. Comparisons of the two tillage methods were also made without lime to determine the degree of response to lime. Lime increased corn yield more than twice as much in no‐tillage culture as in conventional tillage. Lime was essential for highest yields with both tillage methods but the yield increase due to surface applied lime in no‐tillage culture averaged 31.3%, compared to a 13.5% yield increase due to incorporated, lime in conventional tillage culture.

Associated with the larger yield increase from lime in the no‐tillage culture were 1) a higher pH in the 0 to 10‐cm soil layer (averaging 6.4 in no‐tillage compared to 6.0 in conventional tillage) in the eighth year; and 2) larger increase in exchangeable Ca and a reduction in exchangeable AI in the 0 to 10‐cm layer. The pH and exchangeable Ca and AI in the 10 to 20‐cm soil layers from tilled and nontilled soil were almost identical. A highly significant correlation was found between maturity of the corn and yield increase due to lime. Thus, it appears probable that the principal mechanism for the yield reduction caused by the lack of lime was reduced growth. This was especially apparent in early growth stages but was partially overcome later. It was more noticeable in no‐tillage corn than in conventionally tilled corn. At harvest, the increase in dry matter content of no‐tillage corn ears which was caused by lime was larger than that in conventionally tilled corn.

Water use efficiency for the increased corn grain yield due to lime in no‐tillage was calculated to be almost three times that in conventional tillage.
Nutritive Value of Pensacola Bahiagrass Stolons1
Authors: Rodriguez M. , Blue W. G. , Moore J. E.
Published: July 2010

Forage shortage and low forage quality during the winter season are critical in Florida during some years. Pensacola bahiagrass (Paspalum notatum Flugge) produces massive stolon‐root systems with relatively high crude protein concentrations if adequate nutrients are supplied. Preliminary in vitro digestion studies with these stolons indicated high digestibility. An experiment was initiated to study the feed value of this material and to determine the feasibility of using it during critical winter periods. Stolon evaluation was made by chemical analyses and by feeding trials with sheep to determine voluntary intake and nutrient digestibilities. Chopped stolons were mixed with chopped bahiagrass hay to give variable hay:stolon ratios. Each ration was supplemented with 10% molasses and 10% soybean meal. Dry matter and crude protein contents for all rations were approximately 86 and 12.5%, respectively. No difference was found in intake of organic matter or digestible organic matter among treatments. Cellulose digestibility decreased as the proportion of stolons in the rations was increased, but crude protein digestibility increased. Animals on all treatments averaged gains in excess of 5 kg during the 21‐day period. The chopped stolons were not readily accepted by sheep, but the addition of molasses and soybean meal markedly improved palatability. Cattle withheld from feed for 2 days consumed the stolons satisfactorily.
Protein Content and Seed Size Relationships with Seedling Vigor of Wheat Cultivars1
Authors: Ries S. K. , Everson E. H.
Published: July 2010

The source of wheat (Triticum aestivum L.) seed may affect crop growth and yield. Within a genotype, seed that has a higher protein content and/or is larger will produce more vigorous seedlings and sometimes higher yields.

Spring and winter wheat seed collected from five cultivar trials grown at several different locations were used to determine the relative effect of genotype and environment on seed protein and seed size, and these factors were related to the dry weight of seedling shoots (vigor).

Both environment and genotype affected the protein content of the seed. Regardless of genotype or environment, seedling vigor was consistently related to seed protein. Seedling vigor was also related to seed size, but when seed size was eliminated as a factor by using uniformly sized seed, the seed protein content and vigor relationships were significant.
Rooting Density and Water Extraction Patterns for Corn (Zea mays L.)1
Authors: Taylor H. M. , Klepper Betty
Published: July 2010

Because they occur at greater distances from the plant stem, roots deep within the profile often are considered less effective than those near the soil surface.

An experiment was conducted to compare water‐absorbing efficiency, per centimeter of root, of corn (Zea mays L.) roots deep in the profile with that of roots near the soil surface. Plants were grown in a rhizotron compartment with rainfall excluded by a metal cover over the soil. Soil water content was determined with a neutron probe; rooting density, from measurements of roots on the glass viewing surface of the compartment. Leaf area was calculated by a length‐width method and plant height was measured daily. Stomatal aperture was estimated with a pressure drop promoter twice daily.

With few exceptions, soil water content decreased and rooting density increased during the experiment. For the first weeks, transpiration exceeded pan evaporation, but toward the end of the experiment it was about half as much as pan evaporation. Water uptake per centimeter of root was affected most by soil hydraulic, conductivity, and at a given conductivity, it was greater at lower root densities. This effect of root density probably occurred because the roots were younger and more permeable at low root densities than at high root densities. Thus, for the conditions of these experiments, roots deep in the profile were probably more effective per centimeter of root for water uptake than shallow roots because they were younger and were in wetter soil.
Quantity and Frequency of Trickle and Furrow Irrigation for Efficient Cabbage Production1
Authors: Bucks Dale A. , Erie Leonard J. , French Orrin F.
Published: July 2010

Trickle irrigation, with its capability of small, frequent irrigation applications, has aroused considerable interest because of possible increased production and decreased water requirements. For this reason, a replicated field investigation was conducted to evaluate quantity and frequency of trickle, modified‐furrow, and standard‐furrow irrigations on the growth of cabbage (Brassica oleracea capitata), using a moderately saline water on a fine‐textured soil. Trickle and modified‐furrow irrigations were scheduled to supply various quantities of water based on ratios of the plant's estimated consumptive use at frequencies of 3, 6, and 12 days. The modified furrow was a small furrow constructed in the center of the bed to simulate a field practice comparable to trickle irrigation. The standard‐furrow irrigation was based on plant symptoms and on soil‐moisture depletaion criteria. Consumptive‐use measurements were made by gravimetric soil‐moisture sampling on the standard‐furrow irrigation. Recorded data included yield, quality of production, and water‐use efficiency.

Results indicated that the consumptive‐use requirement (38 cm of water in 1972) for high production of cabbage was about the same for all irrigation methods. Maximum production was almost identical for all methods, whereas the application of irrigation water at less than the consumptive‐use rate decreased production for the trickle and modified‐furrow irrigations. Increasing the frequency of trickle irrigations decreased production when the amount of applied irrigation water was near or less than the consumptive‐use rate. Therefore, frequent trickle irrigations may not necessarily be advantageous for cabbage on this soil. Trickle and modified‐furrow irrigation, however, did reduce the irrigation water requirement as compared with the standard‐furrow irrigation, showing that higher irrigation efficiencies can be attained with these new irrigation methods as opposed to conventional methods. Trickle or modified‐furrow irrigation methods have the potential to reduce irrigation water requirements but not consumptive use under many field conditions.
Effect of Disulfoton, Diazinon, and Fensulfothion on Atrazine Absorption by Soybean1
Authors: Penner Donald
Published: July 2010

Organophosphate insecticides are frequently applied in combination with 2‐chloro‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine (atrazine) to corn (Zea mays L.). The objective of this study was to examine the possible interaction of the organophosphate insecticides with s‐triazine absorption and distribution in the plant. Soybeans (Glycine max (L.) Merrill) were selected for study because they do not rapidly metabolize atrazine. This facilitates measurement of possible interaction effects on absorption and movement from root to shoot in the plant. Combination effects resulting in altered phytotoxicity were measured by preemergence and postemergence application of O, O‐diethyl S‐2‐(ethylthio) ethyl phosphorodithioate (disulfoton) and O, O‐diethyl O‐(2‐isopropyl‐4‐methyl‐6‐pyrimidinyl) phosphorothioate (diazinon) to soybeans grown in the greenhouse in the presence of a 1.7 kg/ha preemergence application of atrazine. Preemergence applications of disulfoton increased, whereas post‐emergence applications of disulfoton and diazinon decreased atrazine injury. The effect of disulfoton, diazinon, and O, O‐diethyl O‐(P‐(methylsulfinyl)phenyl phosphorothioate (fensulfothion) on the absorption and translocation of 14C‐atrazine was measured in 7‐day‐old soybean seedlings in nutrient culture following a 4‐hour treatment period. Diazinon and fensulfothion reduced the concentration of 14C‐atrazine in the shoots, primarily the stems, of control plants which received the insecticides and atrazine only during the 4‐hour treatment period. Under these conditions movement of 14C in the primary leaves was enhanced by all three insecticides. None of the soybean seedlings grown in 10−5 M atrazine together with an organophosphate insecticide and then treated with 14C‐atrazine plus insecticide for 4 hours showed greater atrazine uptake than the control. Under these conditions diazinon reduced the atrazine concentration in the roots. Combination effects of Organophosphate insecticides and atrazine on phytotoxicity appear to involve an effect of the insecticides on herbicide absorption and distribution in the plant.
Penetration of Photosynthetically Active Radiation in Corn Canopies1
Authors: Sinclair T. R. , Lemon E. R.
Published: July 2010

The penetration and distribution of light in leaf canopies are essential data to understanding the photosynthetic productivity of a crop. Light sensors which measure photosynthetically active radiation were constructed and traversed through the leaf canopies of six types of corn (Zea mays L.) to observe radiation penetration. Under clear sky conditions two major irradiance levels were observed in the corn canopies. One irradiance level was slightly less than the total radiation above the crop and represented the occurrence of sunflecks penetrating into the canopy. The second irradiance level was much less than the first and was comprised of sky radiation and radiation scattered by leaves. However, a decrease in the amount of direct solar radiation by either an overcast sky or a low sun angle resulted in a single, broad‐band irradiance level.

The data on sunfleck penetration also provided a basis for testing two physical models of light penetration in leaf canopies. Data from corn planted in a uniform, hexagonal pattern was in good agreement with the Poisson model which assumes a random leaf distribution. However, the Markov chain model which introduces a frequency gap parameter, λ, to account for nonuniform leaf distribution was required to obtain good agreement with data recorded in the canopy of corn planted in rows 76‐cm apart. This was especially true for the top part of the row‐planted corn where small, short leaves resulted in large gaps for radiation penetration. The Markov model would be necessary, for instance, to determine the penetration of photosynthetically active radiation to the leaves in the middle of the canopy. Nevertheless, the Poisson model gave good agreement with the measured values for radiation intercepted by the entire canopy of the row‐planted crop.
Effect of Fertilizer and Irrigation on Nitrate‐Nitrogen and Total Nitrogen in Potato Tubers1
Authors: Carter J. N. , Bosma S. M.
Published: July 2010

This study was conducted to determine the effect of N fertilizer and irrigation management on potato (Solanum tuberosum L.) tuber NO3‐N levels and the relationship to the potential health hazard created by high nitrate levels in food products.

‘Russet Burbank’ potatoes grown using different N fertilizer rates, methods of application, and irrigation levels were analyzed for NO3‐N concentration. The NO3‐N concentration in the tubers on a wet weight basis varied from 36 to 131, 34 to 75, and 25 to 50 ppm in the 3 years of this study. The NO3‐N concentration for each year of study was found to be directly related to the level of applied N fertilizer. The initial concentration and increase in NO3‐N due to N fertilizer varied with the season. The addition of manure did not increase the NO3‐N level above those to be expected from similar quantities of inorganic sources of N. Phosphorus fertilizer did not increase the NO3‐N level. The NO3‐N concentration in the tubers where more water was applied at each irrigation was less than on the lower level of applied water at each N rate. These data indicate that greater NO3‐N levels in the tubers will result by increasing N fertilization rates. The levels of NO3‐N obtained in this study were not expected to contribute substantially to the methemoglobinemia health hazard.
Responses of Sunflower Genotypes to Aluminum in Acid Soil and Nutrient Solution1
Authors: Foy C. D. , Orellana R. G. , Schwartz J. W. , Fleming A. L.
Published: July 2010

The overall objective of this research is to develop plant genotypes for better adaptation to acid soil stress factors, such as Al toxicity in subsoils, which cannot be economically corrected by conventional means. The specific objective of the work reported here was to determine the range of A1 tolerance available within the sunflower (Helianthus annuus L.) species.

Thirteen sunflower genotypes were grown for 23 days in greenhouse pots (1.82 kg) of fertilized, acid, Al‐toxic Bladen soil treated either with no lime or with 3,000 ppm CaCO3. With vegetative growth as an index, the genotypes differed widely in tolerance to the acid soil. For example, on the unlimed soil (pH 4.1) the top yield of ‘CM‐2,’ ‘Manchurian,’ ‘Greystripe,’ ‘Peredovik,’ and ‘Romania HS‐52’ were 42, 38, 27, 23, and 11%, respectively, of those on the limed soil (pH 5.5). Corresponding relative root yields (no lime/lime %) were 69, 55, 50, 29, and 7%. The differential Bladen soil tolerance of the Manchurian and Romania HS‐52 genotypes was confirmed in three additional experiments.

The Manchurian genotype was also significantly more tolerant to excess Al in nutrient solutions than Romania HS‐52. For example, with 2, 4, and 6 ppm Al added at initial pH 4.6, the relative top yields (Al/no Al %) were 64, 28, and 28% for Manchurian and 64, 18, and 15% for Romania HS‐52. Corresponding relative root yields were 65, 28, and 21% for Manchurian and 59, 16, and 8% for Romania HS‐52.

The greater acid soil sensitivity of the Romania HS‐52 genotype was associated with a chlorosis of young leaves which did not occur in Al‐toxic nutrient solutions. The stems of Bladen sensitive Romania HS‐52 plants accumulated significantly higher concentrations of Zn than did those of the more tolerant Manchurian genotypes when both were grown on the unlimited Bladen soil. Genotypic differences in Bladen soil sensitivity or susceptibility to the symptoms of leaf chlorosis were not related to any significant differences in the concentrations of Al, Ca, P, Fe, Mn, Cu, or Ni in the plant tops. Fertilization of the unlimed Bladen soil with Mo reduced the chlorosis in Bladen‐sensitive Romania HS‐52 but did not increase growth.

Results of these studies suggest the possibility of breeding genotypes with greater tolerance to acid subsurface soils and the subsequent expansion of sunflower acreage into soil regions where the crop previously has not been successful.
Cool‐Season Perennials vs Cool‐Season Annuals Sod Seeded into a Bermudagrass Sward1
Authors: Decker A. M. , Retzer H. J. , Dudley F. R.
Published: July 2010

‘Midland’ bermudagrass (Cynodon dactylon L. Pets.) is an excellent producer of summer forage in Maryland, but this advantage of high summer yields is reduced by a relatively short growing season in the northern edge of the bermudagrass belt. Cool‐season annuals sod seeded into bermudagrass to extend the pasture season are well documented. However, this requires a seeding each fall which adds to production costs. Theoretically, cool‐season perennials could be substituted for these annuals to eliminate this annual expense.

The present study compared total forage yields and forage distribution of bermudagrass sod seeded with cool‐season annuals [rye (Secale cereale L.), wheat (Triticum aestivum L.), hairy vetch (Vicia villosa Roth)] vs cool‐season perennials [orchardgrass (Dactylis glomerata L.), tall fescue (Festuca arundinacea Schreb.), and crownvetch (Coronilla varia L.)].

Although the perennials significantly increased total forage yields, production was highest when annuals were seeded. It was difficult to maintain uniform mixtures of cool‐ and warm‐season perennials in the same field. The annuals were superior primarily because competition between bermudagrass and the cool‐season perennials was much greater than that between bermudagrass and the cool‐season annuals.

When hairy vetch was seeded with the cereals, yields were increased; at the same time, forage distribution and quality were improved with only half as much nitrogen.

When all factors are considered, bermudagrass plus sod‐seeded, cool‐season annuals was superior to bermudagrass plus sod‐seeded, cool‐season perennials.
Effect of Soil Water and Aeration on Fe and Mn Utilization by Flax1
Authors: Olomu M. O. , Racz G. J.
Published: July 2010

Flax (Linum usitatissimum) plants usually become chlorotic when grown on wet or waterlogged Manitoba soils. Chlorosis has been associated with Fe and Mn concentrations in plants. Reports on levels of Fe and Mn in chlorotic flax plants or factors affecting the utilization of these nutrients by flax were not found in the literature. Thus, experiments were conducted to determine the effects of soil water and aeration on yield and Fe and Mn concentrations in the plant. Plants were grown at 100 and 150% of field capacity. Flax plants became chlorotic on four of six soils when grown at 150% of field capacity. Chlorotic plants had lower yields, contained lower concentrations of iron and higher concentrations of Mn than did non‐chlorotic plants. The ratio of Mn to Fe in chlorotic plants was four or greater. Yields of flax, measured after 35 days of growth decreased with increase in Mn concentration and Mn:Fe ratio of plants. The r values for the relation between yield and Mn concentration and yield and Mn:Fe ratio were −0.73 and −0.76, respectively. Yield of flax increased with increases in the Fe concentration of the plants (r = 0.57).

The effect of soil water (100, 120 or 150% of field capacity) and aeration (soil at 100 or 150% of field capacity with N2, air or no N2 or air passed through the soil) on the Fe and Mn concentrations of flax tops and roots were also investigated. Irrespective of treatment exceedingly large amounts of Fe and only small amounts of Mn accumulated in flax roots. Fe concentration or uptake was not directly related to aeration or oxygen supply in the soil. The ratio of the concentration of Fe in the roots to tops of flax grown on a soil showing chlorosis was lower at field capacity than at 150%. of field capacity. Thus, the reduction in translocation of Fe from roots to tops contributed to chlorosis when soil water content was increased.
Influence of Nitrogen, Phosphorus, and Potassium Applications on Stalk Quality Characteristics and Yield of Corn1
Authors: Arnold J. M. , Josephson L. M. , Parks W. L. , Kincer H. C.
Published: July 2010

Considerable work has been reported on the influence of fertilizer elements, particularly potassium, on yields and lodging of corn (Zea mays L.). Additional information is needed on the influence of other nutrients and different genotypes on stalk quality characteristics and yield. This paper reports the influence of four levels of nitrogen, phosphorus, and potassium on the percent of senescent stalks, crushing strength, rind thickness, stalk lodging, and yield of the six F1 hybrids of a four‐parent diallel of inbreds T101, T105, Till, and T115. The data were obtained using three independent experiments; one associated with each fertility element for 3 years. Nitrogen and phosphorus had little or no influence on stalk characteristics. Potassium additions reduced the percent of senescent stalks and stalk lodging and increased crushing strength and rind thickness. The influence of potassium on senescent stalks was dependent on the hybrid involved. Yield increased with additions of nitrogen and potassium, but phosphorus had little influence.
Effects of Fall Weathering on Yield and Composition of Grain Sorghum Stover1
Authors: Martin Neal P. , Wedin W. F.
Published: July 2010

Increased utilization of grain sorghum (Sorghum hicolor (L.) Moench) stover by livestock maintained for reproductive purposes is suggested, based on its availability. There is little data available, however, on the nutritional value of stover as influenced by fall weathering. We evaluated the dry matter (DM) yield, percentage crude protein (CP), and percentage in vitro dry matter digestibility (IVDMD) of stover, stalks, and leaves in late fall and early winter in Iowa. Two combine‐type cultivars, ‘Nebraska 505’ and ‘RS 610,’ were grown at three populations (128,500; 192,700; and 257,000 plants/ha) from which stover was sampled six different times between September 27 and December 22, 1969, and September 19 and December 28, 1970.

Dry matter yields increased (4.59 to 4.90 metric tons/ha) between grain harvest and killing frost, gradually decreased until late November (3.78 metric tons/ha), and remained unchanged in late December. Percentage CP in the stover gradually increased (6.1 to 6.9%) from grain harvest until late December. Stover IVDMD varied little (57.1 to 56.4%) before frost after which a low of 50.9% resulted in late November. Percentage IVDMD of the leaves dropped from 58.9 to 54.6% between grain harvest and frost.

Stover of RS 610 ranked above Nebraska 505 in DM, CP, and IVDMD yields. Increasing plant population above 128,500 plants/ha increased stover yields slightly. The stover percentage CP and IVDMD obtained before frost suggested adequacy as a ration for ruminants being maintained for reproductive purposes while some supplementation would likely be required later depending on length of postfrost time before harvest or grazing.
Comparative Anatomical and Ginning Characteristics of Two Upland Cotton Cultivars1
Authors: Morey P. R. , Wanjura D. F. , Baker R. V.
Published: July 2010

A large amount of vegetable trash including stems and bracts is collected along with burcotton during stripper harvesting. A substantial amount of this trash is then pulverized during cleaning, both at the gin and at the textile mill, and emitted into the air as microscopic dust. The objective of this study was to determine if variation in bract and pedicel structure occurred in Upland cotton (Gossypium hirsutum L.) cultivars which differed quantitatively in the amount of trash contained in harvested burcotton after machine stripping. Tests in 1972 and 1973 showed that ‘Tamcot SP 21’ had lower levels of sticks and stems and fine trash in machine stripped burcotton and a lower nonlint content in the lint after ginning than ‘Dunn 119’. Anatomical analysis in 1973 revealed significant differences between the same cultivars in the amount of vascular tissue in the pedicel and bract.
Method of Correcting for the Effect of Shaking Time on the Bray P1 Test1
Authors: Hassett J. J. , Walker W. M.
Published: July 2010

The amount of P extracted from soils by 0.025 N HCI+ 0.03 N NH4F (Bray P1 extractant) can be dependent on shaking time. This dependence on shaking time has lead to the use of different shaking times in soil test labs in different states. It was found in this study that a shaking time of 1 or 5 min resulted in extraction of a higher proportion of extractable P from soils with low P1 tests than from soils with high P1 tests.

This report presents a method of estimating an equilibrium P1 test value (Peq) that is independent of shaking time. The Peq value of a soil can be calculated from three or more shaking tunes. The calculated Peq value represented the same proportion of total extractable P in soils with high and low P1 tests. Hence, Peq, values may be better estimates of available P from high P1 test soils than P1 tests based on 1 or 5‐min shaking time.
Cation‐Anion Balance of Field‐Grown Crops. I. Effect of Nitrogen Fertilization1
Authors: Banwart W. L. , Pierre W. H.
Published: July 2010

Plant species differ in their cation‐anion balance, but there are rather substantial variations in the contents of organic anions (C–A) and excess–base (EB), and in the EB/N ratio of plants of a given species when grown under widely different conditions. The causes of such variation within a species are of interest because of the relationship of the C–A in plants to crop growth and the effect of the EB/N ratio of harvested crops in modifying the acidity produced by N fertilizers. The primary objective of this study was to determine the effect of a wide range in amounts of N fertilizer on the C–A and EB/N of several crop species grown under field conditions.

Leaf samples of corn (Zea mays L.) and above‐ground plant samples of corn, oats (Avena sativa L.), and orchardgrass (Dactylis glomerata L.) were taken for analysis from plots of field experiments on several soil types that received different amounts of N fertilizer.

Nitrogen fertilization increased the C–A, EB, and N contents of corn leaves, oats, and orchardgrass. For example, the addition of 358 kg/ha N in one experiment increased the average N content of corn leaves 89 meq/ 100 g or 106% and the EB and C–A contents 36 and 37 meq/100 g or 50 and 52%, respectively (Table 3). Likewise, in an experiment with oats, the addition of N up to 101 kg/ha increased the average EB and C–A 17 and 15 meq/100 g, respectively. The increase in C–A normally associated with an increase in N was much less where large amounts of K fertilizers were applied and was counteracted when moderate amounts of nitrate accumulated in the plants. No consistent effect on the C–A and EB of corn plants was obtained from N fertilization.

Nitrogen fertilizers markedly lowered the EB/N ratio of the three crops studied. In one experiment, the EB/N of corn plants was decreased from an average of 0.91 to 0.53. An EB/N of 0.91 means that 91% of the theoretical acidity from nitrification (of that N removed in the crop) would be expressed, whereas an EB/N of 0.53 means that only 53% of the acidity from nitrification would result.
Metal Halide Lamps for Supplemental Lighting in Greenhouses: Crop Response and Spectral Distribution1
Authors: Duke William B. , Hagin Roger D. , Hunt Julian F. , Linscott Dean L.
Published: July 2010

Light intensity levels and plant growth under metal halide (MH) and fluorescent‐incandescent (FI) lamps were compared.

When crop plants were exposed to the higher light energy (380 to 750 nm, measured) of the MH lighting system, dry weight over a 6‐week period averaged 38% more than for plants exposed to the FI lighting system. Reduced hypocotyl and cotyledon elongation was the initial effect of the MH lamps. Plants under the MH lamps remained darker green, had larger leaves and thicker stems than plants under FI lamps. For one crop, soybeans, total dry matter increased, and the height of the plants was reduced by 33% under MH lamps relative to FI lamps. All plants under the MH lighting systems were sturdier and closely resembled field‐grown plants.