bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Spraying Urea on Winter Wheat, Triticum aestivum1
Authors: Sadaphal M. N. , Das N. B.
Published: July 2010

The effects of different concentrations of urea (1 to 12%) sprayed at heading and blooming and after blooming on the components of yield, yield, crude and true protein, gluten, Ca, P, and niacin content of wheat, were studied over 3 years.

Foliar application of urea caused an increase in the number of kernels per head and 1000‐kernel weight. Concentrations beyond 3% eliminated mottling in grains altogether. Mottling was inversely related to the protein content. Concentrations from 1 to 6% increased the yield of grain irrespective of season and the yield response was linear when spray was given at heading, an increase of 52 pounds per acre (4% of that under check) having been recorded with each increase of 1% in concentration, the maximum increase being of the order 24%. Subsequent sprays were not beneficial.

Urea sprays increased the proportion of grain in total dry matter produced. Spraying urea resulted in considerable increase in both crude and true protein contents, the response in protein to different concentrations being linear at all the three frequencies. Increase in total protein content was largely due to that in the true protein fraction. The range of increase in protein varied from 18 to 34%. Spraying after blooming was more efficient than at heading or at blooming for enhancing the rate of accumulation of protein in grain.

Increases in protein yield per acre due to N sprays ranged from 24 to 60%. Increases in gluten followed the pattern of protein and were of the order of 53 to 70%. Gluten constituted 70% of crude protein and 80% of true protein in nonsprayed wheat and 82% of crude protein and 90% of true protein in N sprayed wheat. While ash and Ca contents remained unaffected P content increased on account of spraying urea. Foliar sprays of N increased the niacin content of grain.
Effect of Temperature and Coating Thickness on the Release of Urea from Resin‐Coated Granules1
Authors: Brown M. J. , Luebs R. E. , Pratt P. F.
Published: July 2010

Resin coatings are very effective in controlling the availability of N from applied urea in moist soil. In leaching studies, 94% of the noncoated urea was recovered in 1 day, compared to a 49% recovery of the N from coated urea (13.2% resin) in 4 weeks of intermittent leaching.

Release rates are controlled by the thickness of the coating and the temperature of the medium. Coatings averaging 13.2% resin markedly decreased release of urea, compared to coatings of 9.0% resin. In the range between 5 to 35C, increased release of urea accompanied increases in temperature. After 4 weeks of incubation and intermittent leaching totaling 20 inches of water, 25 and 67% of the added N were leached from soil at 5 and 35C, respectively. Increasing the temperature 10C was approximately equivalent to doubling the release time within a 16‐week period. Increasing the temperature increases expansion of the capsule and the surface area through which diffusion must take place. This effect is probably supplemental to the effect of temperature on the diffusion phenomena per se. Approximately 99% of the capsules were recovered intact after incubation for 16 weeks at four temperatures between 5 and 35C.
Effects of Seed Age, Producer, and Storage on Corn (Zea mays L.) Production1
Authors: Fleming A. A.
Published: July 2010

In Experiment 1, seed of the same double‐cross hybrid and age from one grower was greatly inferior in field germination and yield to seed produced by another grower. Two‐year seed from Grower L yielded 1393 pounds more corn per acre than 2‐year seed from Grower K. This significant difference in returns at $1.86 cwt amounted to $25.91 per acre. No significant differences occurred in performance of 1‐, 2‐, and 3‐year‐old‐seed of the same hybrid produced by Grower L.

Two‐year‐old seed of Georgia 103 from Grower L had the same percentage of germination as 1‐year‐old seed from Grower M but yielded a significant difference of 1106 pounds ($20.57) more per acre. Differences yielding ability between lots of seed within a hybrid may not be detected necessarily on the basis of germination percentage, even under field conditions.

In Experiment 2, seed of Georgia 101 lost its ability to germinate between the fifth and eighth years of bottle storage. There were no significant differences within hybrids between the treatments other than 8‐year seed for any of the characters studied except germination.

To avoid unnecessary losses, the source of seed within a hybrid should receive special attention. It may be of greater importance than age of seed.
Natural Cross‐Pollination of the Peanut, Arachis hypogaea L., in the Presence of Bees and Thrips1
Authors: Hammons Ray O. , Leuck D. B.
Published: July 2010

On the evidence, tobacco thrips, Frankliniella fusca (Hinds), are not vectors of natural cross‐pollination of the peanut flower in the vicinity of Tifton, Georgia. Cross‐pollination did not occur when plants were caged to prevent bee (but not thrip) visitations to flowers. Cross‐pollination occurred when plants were not caged and bees visited the flowers. Halictid bees were the principal bee visitors.
Effect of Soil Bulk Density and Soil Water Pressure on Emergence of Grass Seedlings1
Authors: Hughes T. D. , Stone J. F. , Huffine Wayne W. , Gingrich J. R.
Published: July 2010

Moisture was the most important factor influencing the emergence of common bermudagrass (Cynodon dactylon (L.) Pers.) and weeping lovegrass (Eragrostis curvula (Schrad.) Nees.) in a clay soil over the range of bulk density and soil water pressure investigated. Both grasses exhibited approximately the same emergence at the −1/3 and −1‐bar soil water pressures. Of those soil strengths and oxygen diffusion rates encountered, none limited seedling emergence of either grass. Small correlation was found between soil strength and seedling emergence.
Diurnal Variation in Growth Rate of Grain Sorghum1
Authors: Johnson Wendell C.
Published: July 2010

abstract

Growth rate of irrigated grain sorghum with moisture not limiting was measured in the field between August 11 and September 4, 1965, near Amarillo, Texas. A growth sensor was used which converted the extension of a grain sorghum leaf from the whorl, or of a head from the boot, into an electrical signal which was continuously recorded on a strip chart recorder.

The minimum growth rate occurred between 7:00 and 9:00 AM on individual days. The growth rate increased rapidly after that and reached a maximum value for the day near noon. The growth rate decreased sharply during a 3‐ or 4‐hr period which began on different days between 4:00 and 7:30 PM and lasted until 8:00 to 10:00 PM. After this evening period of sharp growth rate decline, the growth rate decreased more gradually and paralleled the air temperature decline until the morning growth minimum was reached. (Times stated are Central Standard Time, or true solar time + 50 min.) There was evidence of a double peak in the growth rate curve in the afternoon of a clear day and of a temporary acceleration of growth rate in the early morning when moisture condensed on the foliage.
Macro‐ and Micronutrient Distribution within Ladino Clover (Trifolium repens L.)1
Authors: Wilkinson S. R. , Gross C. F.
Published: July 2010

Ladino clover grown in greenhouse solution culture was separated into leaflets, petioles, stolons, flowers, peduncles, crowns, and roots and each part analyzed for P, K, Ca, Mg, Mn, Fe, Cu, B, Al, and Zn content. Leaflets and petioles of three different ages were also analyzed for these 10 elements. Phosphorus was concentrated in flowers; Al in leaflets; and Mg, Mn, and Fe in the roots. With increasing age of leaves the P and Zn contents markedly declined, whereas Ca increased. Phosphorus treatments affected P concentrations in leaflets without appreciably affecting P distribution patterns.
Available Water in Soil as Influenced by Extraction of Soil Water by Plants1
Authors: Miller D. E.
Published: July 2010

Over a two‐year period, a study was conducted to evaluate the influence of extraction of soil water by plants on the downward flow of water following irrigation and on the amount of water that may be considered as available to the plant. A conventional estimate of available water at an arbitrary time after irrigation may be increased by about 40% of the evapotranspiration that occurs between irrigation and sampling because of the influence of water extraction on downward flow. The data emphasize the lack of precision in the field capacity concept and that soil drainage following an irrigation does not usually become negligible within reasonable times after irrigation.
Factors Affecting Uptake, Yield Response, and Carryover of Molybdenum in Soybean Seed1
Authors: Gurley William H. , Giddens Joel
Published: July 2010

Soybeans (Glycine max (L.) Merr.) were grown on two soils with three lime levels and varying levels of Mo applied to seed and foliage. Seed that contained 0.5 ppm, 19.0 ppm, and 48.4 ppm Mo were planted at three locations. Seed from these locations were planted the 3rd year at one location. When the soil was limed to pH 6.5, and foliar Mo applied, a high Mo content of seed resulted. High Mo seed supplied the Mo needs of the crop and increased soybean seed yields on Mo‐deficientsoils. There was little carryover of Mo into second generation seed. Molybdenum accumulated in cotyledons of seed and there was a higher Mo content of seed on the lower part of the plant than on the upper.
Root Porosity and Growth Responses of Rice and Maize to Oxygen Supply
Authors: Luxmoore R. J. , Stolzy L. H.
Published: July 2010

Rice (Oryza sativa L.) and maize (Zea mays L.) plants were grown in Hoagland solution culture maintained at 7.5 ppm and 0.7 ppm oxygen under artificial illumination.

Adventitious roots were generally more porous than the primary root system and were the larger proportion of the roots after about 30 days growth, indicating that adventitious roots could have considerable significance in internal aeration.

No effect of solution O2 concentration on root porosity of rice or maize was observed, suggesting that gas space development may be less dependent on anaerosis than has been supposed in the literature.

For rice, the dry weight was higher at the lower O2 concentration, whereas growth analysis of maize showed that at the lower O2 concentration the dry weight was lower; this was associated with decreases in both leaf area duration and net assimilation rate.
Response of Lowland Rice to Varying Levels of Soil, Water, and Fertility Management in Different Seasons1
Authors: Pande H. K. , Mittra B. N.
Published: July 2010

Performance of rice on lateritic soil was studied under three levels each of soil submergence, soil fertilization, and soil manipulation in the two rice growing seasons, aus and boro. In both seasons the grain yield was better under submergence than under saturation. The crop under shallow submergence (5 ± 3 cm) yielded as much as under deeper submergence (10 ± 3 cm). The crop growth under soil bulk density of 1.68 g/cc or above, obtained through puddling or compaction, performed equally well. With the increasing level of submergence, the P, Fe, and Si contents of grains increased, but, Mn content decreased in the two seasons.
Yield Components and Water Use by Silage Corn with Irrigation, Plastic Mulch, Nitrogen Fertilization, and Plant Spacing1
Authors: Doss B. D. , King C. C. , Patterson R. M.
Published: July 2010

Corn was grown on a Lucedale fine sandy loam soil to determine the effects of irrigation, plastic mulch, N rate, row width, and plant population on yield components and water use by corn. Irrigation, plastic mulch, and higher plant population increased the dry matter yields of all plant parts. Closer row width increased dry matter yields of stalks and leaves but slightly decreased ear yields. Nitrogen rate had little or no effect on dry matter yields of any plant part. Stalks comprised an average of 45% of the total plant dry weight, ears 36%, and leaves 19%.

Plastic mulch decreased average daily water use rates during the early part of the growing season but had little effect during the latter part of the season. Row width, plant population level, and N rate had little or no effect on water use rates. Daily water use rates during the season for unirrigated corn averaged 0.29 cm for plastic‐covered plots and 0.31 cm for uncovered plots. Average rates for irrigated corn were 0.34 cm for plasticcovered and 0.47 cm per day for uncovered plots.
Diurnal Changes in Leaf Resistance to Water Vapor Diffusion at Different Heights in a Soybean Canopy1
Authors: Stevenson K. R. , Shaw R. H.
Published: July 2010

The effect of soil moisture content and evaporative demand on diurnal variations of leaf resistance to water vapor diffusion were studied at two heights in a soybean (Glycine max L. (Merr.)) canopy. Under soil moisture stress, leaf resistance to water‐vapor diffusion of middle leaves in the canopy increased approximately 2 hr earlier in the day and to a greater extent than the resistance of upper leaves. This indicated a preferential flow of water to upper leaves. It is speculated that the degree of out‐of‐phase change in leaf resistance under stress conditions is related to canopy density.

Leaf resistances of middle leaves decreased at a slower rate under adequate soil water supply than under drier conditions. On days with low evaporative demand, leaf resistances of upper leaves tended to be less (0.8 sec/cm) under the low soil moisture than under the high soil moisture supply. The apparent reduction of stomatal activity in leaves under low evaporative demand and high soil moisture supply is believed related to the lack of development of a small leaf‐water deficit necessary for maximal stomatal opening.
Influence of Previous Crop and Nitrogen Mineralization on Crop Response to Applied Nitrogen1
Authors: Hipp B. W. , Gerard C. J.
Published: July 2010

Experiments were conducted under irrigated, subtropical conditions to evaluate the influence of previous crop on NO3‐N distribution in the soil profile and subsequent response by cotton (Gossypium hirsutum L.) and grain sorghum (Sorghum bicolor (L.) Moench.) to applied N. Responses to N were obtained with cotton and grain sorghum if planted immediately after cabbage (Brassica oleracea var. capitata), but responses to N were small or non‐existent if the area was fallow from September until March. Fall and winter temperatures are warm enough that N mineralization allows accumulation of NO3‐N in the soil profile and may preclude a response from application of N.
Nitrogen Fertilization and Clipping Effects on Green Needlegrass (Stipa viridula Trin.): II. Evapotranspiration, Water‐Use Efficiency, and Nitrogen Recovery1
Authors: White Larry M. , Brown Jarvis H.
Published: July 2010

Soil water and N are the major factors limiting forage production of green needlegrass (Stipa viridula Trin.) on the northern Great Plains. We studied the effects of N fertilization rate and clipping frequency on evapotranspiration (ET), water extraction pattern in soil profiles, water‐use efficiency, and fertilizer N recovery by dryland green needlegrass. Nitrogen was broadcast at 0, 70, and 140 kg of N/ha in November 1968. Green needlegrass was either left unclipped or clipped to a 5‐cm height five times during 1969 at approximately 21‐day intervals.

Green needlegrass showed visual signs of water stress when water was deficient in the surface 30 cm of soil. On undipped plots, 80% of the ET was from the 0‐ to 30‐cm depth. Water‐use efficiency of undipped green needlegrass increased during May and June and decreased during July, but that of clipped plants decreased from May through July. Nitrogen fertilization increased and clipping decreased water‐use efficiency.

Average N recoveries with 70 and 140‐kg rates were 22% for the first year and 8% for the second year. Recovery was highest with 70 kg of N/ha and frequent clipping. Low recovery of N fertilizer was not due to loss of nitrate‐N by leaching. At the end of the first crop season, 7% of the 70 kg N/ha applied and 17% of the 140 kg of N/ha applied the previous year remained in the soil as nitrate‐N.
On the Pressure Chamber Technique for Estimating Leaf Water Potential in Sorghum1
Authors: Blum A. , Sullivan C. Y. , Eastin J. D.
Published: July 2010

The purpose of this work was to re‐evaluate the pressure chamber technique for estimating leaf water potential in sorghum [Sorghum bicolor (L.) Moench], with special reference to problems associated with leaf sample crushing under pressure and pressure rate increase inside the chamber. Pressure chamber readings were compared to Spanner‐type thermocouple psychrometer readings on leave of five sorghum genotypes at several stages of growth.

A leaf sample holder, constructed from Silicon rubber and accomodated into a brass flange, reduced leaf crushing under pressure. It was found that pressure chamber readings (xylem pressure) cannot be directly used as estimate of leaf water potential, but should be corrected according to a calibration against a thermocouple psychrometer determinations of leaf water potential. Different rates of pressure increase in the chamber affected the regression between xylem pressure and leaf water potential. The regression improved with a greater pressure rate increase as indicated by smaller error variance estimate. No differences were detected between genotypes in this regression.

This technique is, therefore, useful if worked out according to a calibration curve at a standard rate of pressure increase.
Rumen Microbial Degradation of Grass Tissue Revealed by Scanning Electron Microscopy
Authors: Akin Danny E. , Amos Henry E. , Barton Franklin E. , Burdick Donald
Published: July 2010

Leaves of ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.) and ‘Coastal’ bermudagrass (Cynodon dactylon (L) Pers.) were studied to relate microanatomical differences to differences in degradation. Leaf sections of each grass were incubated with rumen microorganisms for various times and examined using the scanning electron microscope. Data reveal that tall fescue is degraded more rapidly and extensively than Coastal bermudagrass. These differences agree with in vitro dry matter disappearance investigations conducted on leaf tissue of each grass. Portions of the lignified structures in tall fescue appear to be removed after a 72‐hour incubation, whereas all lignified tissues in Coastal bermudagrass are completely undegraded at this time. Data indicate that the amounts of particular tissues in grass leaves affect the rate of tissue degradation.
Nutrient Concentration Changes in Corn as Affected by Dry Matter Accumulation with Age and Response to Applied Nutrients1
Authors: Terman G. L. , Noggle J C
Published: July 2010

Hybrid corn (Zea mays L.) was sampled each week on field plots of soil testing adequate in P and K at Muscle Shoals, Alabama, in 1972, to relate plant analyses results to growth and maturity. Treatments of N compared were no N, 28 kg/ha at planting + 84 kg/ha topdressed at tasseling, 56 kg/ha at planting, and 112 kg/ha at planting. Plots of cumulative yields vs nutrient concentrations were used to evaluate the results.

Corn yields increased markedly with amount of applied N, but single and split applications of N resulted in similar yields. Concentrations of N in the top leaves, ears, and entire topgrowth also increased at each harvest date with amount of applied N. Applied N also resulted in higher concentrations of P, Ca, and Mg, but lower K concentrations in the top leaves at most sampling dates. At each rate of applied N, concentrations of N in leaves, ears, and entire tops decreased with maturity. Concentrations of P remained about the same; Ca and Mg first decreased and then increased to maturity, whereas the opposite trends resulted for K concentrations. These opposite trends in results from this experiment and from other studies illustrate the strong reciprocal relationship between concentrations of K and Ca + Mg in plants. Nutrient concentration trends with increasing yields and age of plant are influenced in general by amounts of available nutrients and various growth‐limiting factors.
Tolerance of Five Cool‐Season Perennial Grasses to Selected Herbicides1
Authors: Canode C. L.
Published: July 2010

This research was designed to measure the tolerance of five species of perennial grasses to selective herbicides. Herbicides were applied in September or in April preceding production of the first or second seed crop of Kentucky bluegrass (Poa pratensis L.), smooth bromegrass (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), crested wheatgrass (Agropyron desertorum (Fisch. ex. Link) Schult., and red fescue (Festuca rubra L.).

Seed yield of these species was not reduced by isopropyl carbanilate (propham) or isopropyl m‐chlorocarbanilate (Chlorpropham) at 3.4 and 4.5 kg/ha applied in September. Seed yield was significantly reduced by 5.6 kg/ha of propham applied in September to orchardgrass and chlorpropham, applied in September to red fescue. Seed yield was not reduced by 3, 6‐dichloro‐o‐anisic acid (dicamba) at rates as high as 4.5 kg/ha applied to Kentucky bluegrass in September, but was reduced by lower rates applied in April. Other species were less tolerant than Kentucky bluegrass to dicamba applied in both September and April. Seed yield of Kentucky bluegrass was reduced by 4‐amlno‐3,5,6‐trichloropicolinic acid (picloram) at 0.6 kg/ha applied in September before production of the first seed crop, but this species tolerated as much as 2.2 kg/ha applied to older stands. Other species were less tolerant than Kentucky bluegrass to picloram. Applicatlou of (2,4‐dichlorophenoxy)acetic acid (2,4‐D) to 2.2 kg/ha in September did not significantly reduce seed yield of any of the species, but applications of 1.7 or 2.2 kg/ha in April reduced seed yield of smooth bromegrass and red fescue.

Application of propham, chlorpropham, or 2,4‐D did not reduce seed germination of any species. Application of picloram in September also did not reduce germination of grass seed, but application of 1.7 kg/ha or more in April reduced germination of smooth bromegrass seed in 1969 and red fescue seed in 1966 and 1969. Dicamba at the higher rates applied in September reduced seed germination of two grasses and when applied in April reduced seed germination of most of the grasses.
Diurnal and Seasonal Trends in Nitrate Reductase Activity in Field Grown Sorghum Plants1
Authors: Teare I. D. , Manam Radhamohanrao , Kanemasu E. T.
Published: July 2010

Nitrate reductase activity in plants has been suggested as a sensitive indicator of water stress. We studied nitrate reductase activities in sorghum (Sorghum bicolor L. Moench cv. ‘Pioneer #846’) using in vivo assay and compared activities by leaf position on culms and various positions on leaves — through diurnal and seasonal trends (from stalk elongation to maturity, 1971). We related leaf water potential (measured with pressure bomb) and atmospheric demand for water (solar radiation measured with a pyranometer) with nitrate reductase activity. Nitrate reductase activity was highest in the upper, fully‐expanded leaves — in the flag leaf at the 5.5 stage of physiological development. We also compared relative amounts of hydrocyanic acid in sorghum, which other workers have observed in relation to physiological age, with seasonal nitrate reductase activities. Diurnal water stress (shown as leaf water potential in relation to high solar radiation) lowered nitrate reductase activity. Nitrate reductase activity decreases as plant age and water stress increases and likely decreases as hydrocyanic acid increases.
Fertilizer Studies with Groundnuts on the Brown Sands of Guyana. I. Effect of Nitrogen, Inoculum, Magnesium, and Fritted Micronutrients1
Authors: Chesney H. A. D.
Published: July 2010

The Brown Sands are a dominant soil group in South Guyana. They are coarse textured ‐ sand to sandy loam; highly leached; acid, and, although not naturally fertile, they appear suitable for large scale cultivation of groundnuts [Arachis hypogoea (L.)].

Two experiments were conducted on these soils to determine the effect of fertilization and inoculation on crop performance.

In the nitrogen × inoculum (Rhizobium japonicum) series, N did not influence yield. It caused a decrease in nodulation with the effect becoming more marked with constant cropping. Inoculum up to 226 g/27 kg seed increased yields but decreased nodulation only at the last of three plantings. Both Mg and fritted micronutrients had no effect on yields; these results were difficult to explain considering the highly leached nature of this soil.
Soybean Response to Stand Reduction and Defoliation1
Authors: Teigen James R. , Vorst James J.
Published: July 2010

‘Beeson’ soybeans (Giyeine max (L.) Merr.) were treated at a vegetative (V7) and a reproductive (R3) stage of development to determine how soybeans respond to two important components of hail damage‐stand reduction and defoliation. This information is used by the crop hail industry to construct crop loss charts. Treatments consisted of 0, 25, and 50% levels of stand reduction and defoliation in all combinations at both growth stages. Defoliation was accomplished by removing designated percentage of each leaflet with a hand shears. Stand reduction alone reduced seed yield a maximum of 17% while defoliation alone reduced seed yield a maximum of 6%. The largest yield reduction (23%) occurred when the 50% stand reduction and 50% defoliation treatment was imposed during the reproductive stage. Plant height at maturity and lodging were reduced slightly by both defoliation and stand reduction treatments with stand reduction causing the most change in these parameters. More pods and heavier seed were produced on plants remaining after stands were reduced. Defoliation during the reproductive stage reduced seed yield, number of pods per plant, and lodging more than similar treatments applied at the vegetative stage. Number of seeds per pod was not significantly influenced by the treatments. From the data we concluded that low levels of defoliation removed leaf tissue which contributed little to seed production, and the soybean community was able to compensate for plants removed from the population. Most of the compensation was due to an increase in number of pods per plant.
Centipedegrass Cold Tolerance as Affected by Environmental Factors1
Authors: Johnston W. J. , Dickens Ray
Published: July 2010

Centipedegrass [Eremochloa ophiuroides (Munro) Hack.] is an excellent lawn grass throughout much of the lower South. However, lack of cold tolerance has limited its use. An environmental chamber study was conducted to determine: 1) the rate at which cold tolerance is developed and lost in centipedegrass and 2) the effect of photoperiod and temperature on cold tolerance development in an effort to identify factors or conditions contributing to cold damage in centipedegrass.

Development of cold tolerance was determined by cold hardening (16 C day, 4 C night, 12‐hour photoperiod) centipedegrass for 0, 10, 20, 30, or 40 days. Loss of cold tolerance was determined by transferring cold hardened plants to favorable growing conditions for 0, 2, 4, or 6 days. In the photoperiod‐temperature study, plants received 8, 12, or 16 hours of light at 23 C followed by either a 23 C or 4 C night. In each study, following a 4‐hour exposure at −7 C, plants were returned to favorable growing conditions. Foliage kill and survival were determined after 7 and 21 days, respectively.

Hardening periods greater than 10 days caused no increase in survival and only a slight reduction in top‐kill. Cold tolerance was lost rapidly; i.e., cold hardened plants exposed to 2 days of favorable growing conditions showed the same injury as unhardened controls. Photoperiod alone did not affect cold tolerance; however, a combination of a low night temperature (4 C) and short‐photoperiod (8 hours of light) gave maximum cold tolerance. In conclusion, centipedegrass acquires and loses cold tolerance within a few days, an important consideration in the lower South where winters are often interrupted by periods of warm weather.
Interaction of Water Potential and Temperature Effects on Germination of Three Semi‐arid Plant Species1
Authors: Sharma M. L.
Published: July 2010

Studies evaluating simultaneous effects of more than one environmental factor on germination are rather scarce. Population dynamics of plant species would be understood better provided these effects are known. A study was undertaken to investigate the interactive effects of temperature with matric and osmotic potential on germination characteristics of three dryland species, Danthonia caespitosa Gaudich, Atriplex nummularia Lindl. and A. vesicaria Hew. ex Benth. Matric potentials were simulated by aqueous solutions of polyethylene glycol (mol. wt. 20,000) and their effects were compared with those of osmotic potential created by sodium chloride solutions.

The rate and total germination of all the species declined with decreasing water potential. The germination rates increased with increasing temperature but final germinations were highest at intermediate temperatures (20 to 25 C). All species germinated better at low water potentials in the vicinity of the optimum temperatures. Interactive effects of temperature with both types of water potential were highly significant for all species. In general, osmotic effects were qualitatively similar to those of matric potential, although asmotic inhibition of germination was reduced at low temperatures.

Both Atriplex had reasonable germination at extreme temperatures (5 C, 40 C) while D. caespitosa did not germinate at all. At low water potential (—15 bars) A. nummularia germinated in the range of 15 to 40 C, D. caespitosa germinated only at 25 C while A. vesicaria had poor germination at all temperatures. The order of species with respect to their capability to germinate against environmental stress was A. nummularia > A. vesicaria > D. caespitosa. It follows that because of capability of Atriplex spp. to withstand extreme temerature and water potential, germination is possible following rains during summer as well as winter, however Danthonia is likely to germinate only during spring and autumn.
Incorporation Depth and Rainfall on Weed Control in Soybeans with Metribuzin1
Authors: Wax L. M.
Published: July 2010

Metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthlo)‐as‐triazin‐5)4H) one] controls several species of annual broadleaf weeds in soybeans [Glycine max (L.) Merr.]; however, inconsistent weed control and excessive crop injury sometimes result from the use of metribuzin. To determine the extent to which rate of application, rainfall, and depth of incorporation influence weed control and crop injury with metribuzin, microplot and large plot field experiments were conducted in 1973 and 1974. In microplot studies, metribuzin provided 67 to 100% control of comon ragweed (Ambrosia artemisiifolia L.), prickly sida (Sida spinosa L.), velvetleaf (Abutilon theophrasti Medic.), and jimsonweed (Datura stramonium L.). Degree of weed control increased with a corresponding increase in herbicide rate from 0.56 to 0.84 kg/ha. Increased control of these species (and slightly greater soybean injury) resulted from increasing depth of soil‐incorporation from 0 to 7.6 cm. Control of common cocklebur (Xanthium pensylvanicum Wallr.) and ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.] was only 35 to 75% but control did improve with increased herbicide rate and depth of incorporation. Abundant rainfall within 10 days after treatment resulted in 88 to 99% control of velvetleaf and 85 to 95% control of jimsonweed. However, control of these two weeds was poor under limited rainfall, unless metribuzin was incorporated to a depth of at least 5.1 cm. Ivyleaf morningglory was not controlled well with metribuzin in the microplots (12 to 62%) regardless of rate, rainfall, or depth of incorporation. In the large plot studies, metribuzin, under moderate‐to‐abundant rainfall conditions, controlled several annual broadleaf weed species, whether applied preemergence to the soil surface or used as a preplant soil‐incorporated treatment. Metribuzin injured soybeans and caused significant yield reduction when soil‐incorporated at 1.12 kg/ha.
Differential Aluminum Tolerance of Sugarbeet Cultivars, as Evidenced by Anatomical Structure1
Authors: Keser M. , Neubauer Benedict F. , Hutchinson F. E. , Verrill D. B.
Published: July 2010

Early attempts to cultivate the sugarbeets (Beta vulgaris L.) in Maine were not successful due to large amounts of soluble Al in acid soils. The objectives of this study were to determine if a differential tolerance to Al exists among sugarbeet cultivars grown world‐wide, and whether such tolerance could be detected in early stages of seedling growth by examination of morphological and anatomical structures.

All cultivars were grown in culture solutions of 0 and 4 ppm of Al at pH 4.8. Four parts per million was used because this concentration in culture solution was toxic to cultivar IS 922, a cultivar previously grown on a commercial basis in Maine. After 10 days growth, some cultivars exhibited more tolerance than others. This study concentrated on eight cultivars of the 116 originally tested. Cultivar IS 922 was used as the control; two cultivars were chosen for low tolerance, and five for their high tolerance to Al toxicity.

At 0 ppm of Al, all cultivars showed normal anatomical and morphological development. At 4 ppm of Al, the two most susceptible cultivars accumulated large amounts of aluminum phosphate. The meristematic zones of primary and lateral roots of these plants lost their normal pattern of organization and further growth appeared inhibited. Variability existed within each of the five cultivars chosen for their apparent tolerance, some plants accumulated aluminum phosphate and others did not.

This study indicated that differential tolerance to Al exists among sugarbeet cultivars, and among individual plants within the same cultivar. Tolerance can be determined at early developmental stages.
Influence of Water and Fertilizer Management on Yield and Water‐input Efficiency of Corn1
Authors: Rhoads F. M. , Mansell R. S. , Hammond L. C.
Published: July 2010

Damaging plant water stress develops in corn grown on coarse‐textured, low water retaining soils of the south‐eastern U.S. during 1 to 2‐week periods without rainfall. However, in most years rainstorms cause leaching of soluble fertilizers from the root zone. This study was conducted to evaluate efficiency of water input in terms of corn grain yield per unit of water, with two fertilizer application methods under three soil‐water management systems on a Troup loamy sand (Grossarenic Paleudult). Water management consisted of (a) control — natural rainfall only, (b) trickle irrigation scheduled daily (0.64 cm/day), and (c) trickle irrigation scheduled by tensiometer (1.30 cm/application). Tensiometers were placed in each treatment at six depths between 15 and 150 cm below the soil surface and readings were recorded daily. Methods of applying fertilizers were designated (a) conventional — 1/3 of N and all P and K applied broadcast preplant, and remainder of N applied in two sidedressings; (b) program fertilization — N‐P‐K applied broadcast small increments (5, 5, 10, 20, 20, 20, and 20%) at 2‐week intervals after corn emerged. Average grain yields for the above water management treatments were 2,790, 4,160, and 5,700 kg/ha respectively. Conventional fertilization had an average grain yield of 3,680 kg/ha and program fertilization 4,760 kg/ha. Water‐input efficiencies based on grain yields and total water input were 57, 42, and 76 kg/ha/cm for no irrigation, daily irrigation, and tensiometer scheduled irrigation respectively. Highest irrigation water.input efficiency (150 kg/ha/cm) occurred with program fertilization and tensiometer scheduled irrigation. Irrigation water‐input efficiency was lowest (10 kg/ha/cm) with corn receiving daily irrigation and conventional fertilization.
Root Growth Along Plexiglas Surfaces by Sugarcane Under Different Soil Salinity Conditions1
Authors: Gerard C. J.
Published: July 2010

Root growth responses by sugarcane (Saccharum officinarum L.) to stress induced by salinity as a function of time or growth stage have not previously been investigated. This type of investigation is essential to a better understanding of the tolerance of plants such as sugarcane to salinity or stress. Root environment chambers seem to provide the best opportunity to study the growth interactions of roots and tops of plants and their environment. Root growth in soils irrigated with waters with electrical conductivities of 1.1, 5.0, and 8.0 mmhos/cm varied with stage of plant growth, time and salinity treatments. Root growth of sugarcane was greatest at soil depths of 20 to 60 cm in May, June, and July, a period of high growth rate and high evaporative conditions. During these months, average root intensities of sugarcane, irrigated with waters with salinities of 1.1, 5.0, and 8.0 mmhos/cm, were about 0.5, 1.0, and 1.5 mm/cm2, respectively. Moisture stress induced by osmotic potentials of about −1.8 and −2.9 bar and high evaporative conditions stimulated root intensities but reduced top growth by 22 and 50%, respectively. These studies using root chambers have contributed to a better understanding of the interactive influences of stages of plant growth, salinity, and environment on root growth by sugarcane.
Sensitivity of Sesame to Various Salts1
Authors: Nassery H. , Ogata G. , Maas E. V.
Published: July 2010

Plants tolerate widely varying proportions of salts in the root media but nutritional imbalances and specific ion toxicities may occur if one salt predominates under saline conditions.

The relative sensitivity of sesame (Sesamum indicum L.) to various ions and the nature of the specific ion toxicities were studied in water culture experiments. At 0.10 MPa osmotic pressure, NaNO3, NaCl, Na2SO4, and CaCl2 reduced the yield (shoot + pods) of Sesame by about 15, 26, 33, and 65%, respectively. At 0.20 MPa, Ca(NO3)2 was more injurious than NaCl or any combination of the two salts.

Chemical analyses indicated that sesame roots did not accumulate C1, Na, and Ca readily, since the accumulation factors for these ions were near or less than 1. However, leaves accumulated these ions to a considerable extent. Leaf Na concentrations of 162 µmol/g fresh wt were associated with necrosis but no evidence of C1 toxicity was noted. Calcium‐induced necrosis seemed indirect, possibly a consequence of decreased Mg concentration. Ion concentration gradients indicated a specific accnmulation of Na in the stem. This retention was greater, and less Na reached the leaves, when the anion was C1 than when it was SO4, a difference that may explain the greater sensitivity of sesame to Na2SO4 than to NaCl.

The high sensitivity of sesame to single‐salt salination emphasizes the importance of using salt mixtures in salt tolerance studies. At extreme Na‐Ca ratios, ionic imbalance predominates and growth suppression exceeds that due to osmotic stress.
Nitrogen Fertilization Increases N and Alters Amino Acid Concentration of Cottonseed1
Authors: Elmore C. D. , Spurgeon W. I. , Thom W. O.
Published: July 2010

Utilization of seed proteins from cotton (Gossypium hirsutum L.) as an ingredient of food products for nonruminant animals may provide producers with a salable seed commodity in addition to oil and meal. It was important to confirm and more fully establish the effects of N fertilization on cottonseed protein concentration and protein quality (amino acid composition). In order to achieve this, seed was collected in 1976 from a N fertility experiment which had been established with the same N rates the previous 2 years. Cotton (‘DES 56’ was grown on a Dundee silt loam soil, a fine‐silt, mixed, thermic, Aeric Ochraqualfs, with four replications. The experimental design was a split‐plot with N rates (67, 90, 112, 134, and 157 kg ha‐1) as the main plots and time of application (preplant, 1/2 preplant‐1/2 sidedressed, and sidedressed) as subplots (the same plots received the same treatment each year). We measured yield of seed cotton, seed N concentration and amino acid composition.

In 1976 the higher N rates increased seed N concentrations from 6.05% N up to 6.60% N, whereas time of application had no effect. Application of N decreased lysine and increased arginine concentration, whereas histidine, serine, tyrosine and phenylalanine were affected by time of application. Glycine was affected by both rate and time of application. Correlation of seed N concentration with amino acid concentration showed that arginine, cysteine and proline were positively related and that lysine, histidine, and threonine were negatively related to seed N. The effects produced by application of fertilizer N to cotton in a field situation result in seed N and amino acid concentration similar to results reported previously in an unusual field situation and allow for better prediction of N effects on cottonseed composition.
Soil and Plant Parameters Associated with Grass Tetany of Cattle in Kansas1
Authors: Karlen D. L. , Ellis R. , Whitney D. A. , Grunes D. L.
Published: July 2010

Few researchers in the United States have attempted to correlate the soil and plant parameters related to the grass tetany problem. To investigate those correlations, we identified areas in Kansas where outbreaks of grass tetany had been diagnosed, and collected forage and soil samples from fields where grass tetany had occurred in grazing cattle. Forage samples were analyzed for K, Ca, and Mg; soil samples were analyzed for pH, exchangeable K, Ca, and Mg, cation exchange capacity and cation activities. Forage K, Ca, and Mg concentrations and equivalent ratios (Mg/K) were correlated with soil‐test parameters and soil exchangeable Mg/K ratios. Chemical analyses indicated forage samples had enough K and Ca for proper nutrition of lactating beef cows, but Mg concentrations were generally less than the 0.2% level essential to maintain normal blood serum Mg concentrations. Low Mg concentrations in the forage resulted in the equivalent ratios [K/(Ca+Mg)] that exceeded 2.2. The soil was fairly high in K and adequate in Ca. Magnesium saturation of the surface and the subsoils ranged from 3 to 45% and, except in a few locations, a response to fertilizer Mg would be highly unlikely. Ion activities showed that Ca was the predominant cation in the soil; Mg activity was about one‐third that of Ca and twice that of K. Potassium activity was most closely correlated to the forage K concentration in wheat (Triticum aestivum L.), whereas, Mg concentrations in wheat forage were most highly correlated with the subsoil Mg saturation percentages and the subsoil exchangeable Mg/K ratio. Magnesium concentrations in fescue (Festuca arundinacea Schreb.) and bromegrass (Bromus inermis Leyss.) correlated most highly with surface soil Mg activity and exchangeable Mg measurements. The correlation coefficients indicated that none of the soil‐test parameters were entirely successful in identifying soil characteristics important in the tetany syndrome. We feel that in Kansas, environmental and management factors are more important in the incidence of grass tetany than the soil's characteristics.
Measuring Sod Strength with an Instron Universal Testing Instrument
Authors: Burns Robert E. , Futral J. Gordon
Published: July 2010

Sod strength is an important factor in sod production. To aid in determining the strength accurately and consistently a method was developed using the Instron Universal Testing Instrument which provides for a preset rate of stretching of a uniform length of sod. The pull is in a controlled direction and the force applied is recorded on a chart that not only yields the force required to break the sod but also the amount the sod stretched prior to breaking and the pattern of breakage. The cost of the equipment, other than the Instron tester, is reasonable and can be constructed in most shops.
Aluminum Toxicity, Nodulation, and Growth of Stylosanthes Species1
Authors: de Carvalho Margarida M. , Edwards D. G. , Andrew C. S. , Asher C. J.
Published: July 2010

Aluminum toxicity is an important limitation to legume growth on many acid soils. Stylosanthes species are often grown on such soils, but effects of A1 on their growth are poorly understood. Effects of four solution Al concentrations (0, 25, 75, and 125 µM) on the growth of six Stylosanthes species was examined on plants supplied with 500 µM NH4NO3 and on plants inoculated with Rhizobium CB 756.

Aluminum toxicity depressed growth more severely in those plants dependent on symbiotic N2 fixation than in those supplied with combined N. At 25 µM Al, S. hamata (L.) Taub. and S. fruticosa (Retz) Alston exhibited high tolerance when dependent on symbiotic N2 fixation, while the other four species were less tolerant. Yield of all six species was strongly depressed at 125MµM Al, irrespective of the N source.

The greater sensitivity of the inoculated plants to Al toxicity was associated with a strong reduction in nodulation f all species. Aluminum delayed nodulation in all species except S. hamata, reduced the number of plants which nodulated in S. guianensis (Aubl.) Sw., S. scabra Vog., and S. viscosa Swartz, and reduced the number and dry weight of nodules in all six species. Greater effects of Al on nodule weight than on root weight were observed particularly in the more poorly nodulated species S. guianensis, S. scabra, and S. viscosa. Tolerance to Al by the various species thus appears to be dependent on their ability to nodulate and develop an effective symbiosis in the presence of Al, and on the inherent sensitivity of the host plant to Al.
Continuous Cultivation and Soil Productivity in the Semi‐Arid Savannah: The Influence of Crop Rotation1
Authors: Lombin L. G.
Published: July 2010

With continuous cultivation replacing the traditional bush‐fallowing system in the West African savannah zone, farming is becoming more fertilizer‐dependent for high yields. It is imperative that cheaper means of augmenting soil fertility be explored to supplement the use of mineral fertilizers. A rational rotation scheme will enable the crops to utilize the limited amount of fertilizers in a complementary manner. The present study evaluated the effects of nine sequences of growing cotton (Gossypium hirsutum L.), sorghum [Sorghum bicolor (L.) Moench], and groundnuts (Arachis hypogaea L.) on soil productivity and crop nutrition at Samaru in northern Nigeria.

The 8‐year study was conducted on a sandy loam soil (Typic Ustropept isohyperthermic family). The sequence treatments were: continuous sorghum, cotton, and groundnuts; sorghum followed by groundnuts or cotton; groundnuts followed by sorghum or cotton; and cotton followed by sorghum or groundnuts. All crops were supplied with adequate amounts of the appropriate basal fertilizers each year. Rotation effects on the yield of each crop were measured over 7 years and in the final year the whole field was ploughed, treated with uniform N and P fertilizers, and seeded to maize (Zea mays L.). Earleaf samples were taken at 50% silking stage for chemical analysis.

Sorghum yielded consistently higher when preceded by groundnuts than when preceded by cotton. Continuous sorghum significantly depressed yield. On the average, groundnuts performed just as well when preceded by sorghum as when preceded by cotton but yielded significantly less when continuously cropped. Cotton following sorghum consistently and, on the average, significantly outyielded cotton following groundnuts or cotton following cotton. However, continuous cotton yielded just as well as when preceded by groundnuts. The sequences which included groundnuts gave the best maize yields with the highest, 4,480 kg/ha, from the continuous groundnuts, compared to 3,570 kg/ha from continuous cotton and 2,500 kg/ha from the continuous sorghum plots. Plant tissue analysis indicated greater N availability after groundnuts followed by cotton and sorghum in that order.

Most of the rotational effects especially on sorghum were most attributable to residual soil N. A continuous monoculture of any of the three crop appears inadvisable. For maximum yields, the best sequence would be groundnuts followed by sorghum and cotton in that order.