bluuebunny/crossref_metadata_2025 huggingface dataset:
Destruction of Sod‐seeded Legume Seedlings by the Snail (Polygyra cereolus1
Authors: Kalmbacher R. S. , Minnick D. R. , Martin F. G.
Published: July 2010

Florida's perennial forage grasses, dormant during winter and early spring, provide little new forage unless overseeded with a cool‐season crop such as clover (Trifolium spp.) or alfalfa (Medicago sativa L.). Sod‐seeding legumes in bahiagrass (Paspalum notatum Flügge) has resulted in poor establishment unless areas were desiccated with 0.28 kg/ha of paraquat and hurned 48 hours later. Poor stands were believed to be due to seedling loss by the snail (Polygyra cereolus Muhlfeld). These experiments were designed to test this hypothesis and determine if burning killed snails.

Five experiments were conducted. 1) Populations were estimated by counting snails in 0.3m2 areas and by tallying snails in traps. 2) To determine legume mortality rate, 0, 1, 3, 5, and 7 snails were placed in enclosures with 20 white clover (T. repens L.) seedlings. 3) In a similar experiment two or four snails were exposed to 40 white clover seedlings drilled in rows. 4) Alfalfa, red (T. pratense L.) and white clover were exposed to snails to determine differences in legume susceptibility. 5) Finally, the temperature was recorded 2.5 cm above, 2.5 cm below, and at soil surface during the burning of bahiagrass. Snails were placed on the soil before the burn and their mortality was determined.

During a 44‐day trapping period in newly seeded legume plots there was an average total of 13.6 snails found vs. 14.0 snails in unseeded bahiagrass. The number of snails per 0.3m2 was 0.9 vs. 0.84 snails in the respective areas.

Greenhouse studies indicated that P. cereolus was responsible for legume mortality. White clover was more susceptible to loss than red clover or alfalfa. More than one snail per 20 seedlings constituted a threat to legume establishment particularly when added to losses from other causes.

Burning bahiagrass after desiccation with paraquat resulted in 98% mortality of P. cereolus. Temperatures at the soil surface rose from 27 to 83 C in 75 sec then dropped to 37 C after 5 min.
Effect of Surface Winds on the Spectral Signatures of Crops1
Authors: Rao V. R. , Brach E. J. , Mack A. R.
Published: July 2010

Spectral interpretation of quantitative measurement of the reflected radiation from plants by remote sensing requires consideration of the environmental conditions and structural aspects of the plant under which the measurements were made. Depending on wind speed and direction, it was found that for certain plants, such as cereal crops, radiance fluctuated 10 to 20% more in the 450 to 650 nm than in the 650 to 750 nm range. Wind speeds up to 32 km/hr caused increasingly greater fluctuation for cereal crops than for clipped sod and bare soil. A calibrated grey reference scale showed little effect of wind within the range of speeds observed in this study.
Role of Root Temperature on Shoot Growth of Two Kentucky Bluegrass Cultivars1
Authors: Aldous D. E. , Kaufmann J. E.
Published: July 2010

Shoot growth inhibition and changes in carbohydrate levels occur in cool‐season grasses under midsummer conditions. Cultural practices, such at thatch removal or topdressing, could alter high temperature extremes of the crown and root. Thus, the objective of this study was to determine the role of root temperature on shoot growth rate and water soluble carbohydrate (WSC) levels in plant parts of ‘Merion’ and ‘Nugget’ Kentucky bluegrass (Poa pratensis L.).

The turfgrasses were established from seed on coarse sand in the greenhouse. After 12 weeks the pots were transferred to an environmental growth chamber where air temperatures were increased from 22 to 38 C in 4 C increments every 2 weeks. The effects of root zone temperatures controlled at 22 C (CRT) were compared to noncontrolled temperatures (NRT) in which the root zone was allowed to equilibrate with the air temperature. Shoot growth above 4.0 cm. was clipped at the end of each temperature increment from 22 to 34 C. After the 38 C exposure plants were separated into verdure (live leaf tissue), “thatch” (dead leaf tissue), crowns, and roots.

Shoot growth of Merion Kentucky bluegrass grown at NRT, was greatest at 26 C and was significantly reduced at 30 and again at 34 C. Shoot carbohydrate levels were lowest at 26 and 30 and highest at 34 C. At 38 C, verdure and crown carbohydrate levels were significantly higher than those of the roots.

The growth rate of Nugget (NRT) at 26 C was not as rapid as for Merion. Shoot WSC levels were high at 26, 30, and 34 C compared to Merion Kentucky bluegrass. At 38 C, root WSC levels were significantly higher in roots than verdure or crown. The greater high temperature tolerance of Nugget was documented through a higher verdure‐thatch ratio.

Survival of both cultivars was enhanced by controlling the root temperature at 22 C (CRT). Shoot WSC levels at all temperatures were significantly lower at CRT compared to NRT in Nugget. This was true in Merion only at 34 C. Root WSC levels in Merion at CRT were at the high level found for Nugget at both NRT and CRT. Shoot growth cessation at supraoptimal temperatures may result from a high temperature‐labile process in the root. Loss of root carbohydrates appears to increase the temperature lability of the process.
Dry Matter and Morphological Responses to Temperatures of Alfalfa Strains with Differing Ploidy Levels1
Authors: Arbi Nitza , Smith Dale , Bingham E. T.
Published: July 2010

Alfalfa (Medicago sativa L.) is grown in a diversity of temperature areas, but there is little information on the response to temperature of strains of different ploidy levels. The objective was to study the response of alfalfa strains of 2x, 4x, and 6x levels of ploidy when grown at three different temperature levels. Plants were grown from seed in pots of soil in three growth chamber regimes; hot (H) 33 C day/24 C night, warm (W) 27/18 C, and cool (C) 21/12 C. All chambers had 18‐hour daylengths. Plants were harvested with two schedules; (i) by date (43 days after seeding) and (ii) by maturity (at first flower). First flower stage generally was delayed as temperatures decreased. The 2x was the first strain to flower in the H and W regimes and 4x in the C regime, while the 6x strain was last to flower in all regimes. At the 43‐day harvest, shoot height and weight of plant parts for each strain generally were highest in the W regime, followed in order by the H and C regimes. Weights of plant parts at first flower for each strain generally were highest in the C regime, followed in descending order by the W and H regimes, except that 6x yielded least in W. Highest herbage growth rate at first flower was in the C regime for the 2x and in the W or C regime for the 4x, while the rate was similar at all temperatures for the 6x. Total plant growth rates (herbage plus roots) of all three strains at first flower were highest in the C regime followed in descending order by the W and H regimes, except 6x was similar at H and W. Leaf area, leaf weight, and specific leaf weight (SLW) generally increased as temperature decreased. However, leaf area of 2x cut by date and SLW of fix cut at first flower were lowest in W rather than H regime. Thus, the strains reacted differently to temperature. The 2x appeared to grow best in the C regime and the 4x in either the W or C regime. The 6x showed a broad adaptation to temperatures, growing about the same at all temperatures. Development of alfalfas with different ploidy levels than the cultivated tetraploids may be a means of obtaining cultivars with broader temperature adaptation or with better adaptation to low or high growing temperatures.
Rapid Evaluation of Foliar Fertilizer‐induced Damage: N, P, K, S on Corn1
Authors: Neumann Peter M.
Published: July 2010

Foliar spraying of crops with fertilizer solutions often causes leaf bum, which reduces the photosynthetic area of the leaves and can reduce yields. Damage can be avoided sometimes by careful control of factors such as spray droplet size, wetting agents, ambient temperature, pH, and concentration of solutes. However, information concerning the mechanism inducing burn damage or the comparative merits of different fertilizer sources of the same mineral is limited. The objects of this work were: 1 to use a rapid laboratory assay to compare the damaging effects of various fertilizer sources of N, P, K, and S on leaf cell membranes, 2 to identify the mechanism of membrane damage by fertilizer solutions, and 3) to make a preliminary evaluation of any correlation between solute‐induced membrane damage and leaf bum in the field. The laboratory assay consisted of a 4‐min vacuum infiltration of 0.3‐cm leaf segments with test solution followed by assay of UV‐absorbing materials leaked subsequently into a distilled water rinse. Threshold concentrations of fertilizers causing membrane damage symptoms were determined for nine fertilizer sources.

Damaging concentrations of N ranged from 3.5 to 31 g/liter depending on the fertilizer assayed. Damaging concentrations of various P, K, and S sources ranged from 3.8 to 11 g/liter for P, 12.2 to 22 g/liter for K, and 6.4 to 8.2 g/liter for S. No evidence was found for the existence of a causal relationship between either pH, molarity, conductivity, or osmotic potentials of test solutions and the onset of membrane damage. Preliminary field trials showed that the assay could predict damage trends for urea and urea phosphate sprays.
Yields of Irrigated Grass and Legume Pasture Mixtures in the Northern Rocky Mountain Area1
Authors: Cooper Clee S.
Published: July 2010

Grass‐legume mixtures are of major importance for irrigated pasture in the western United States and provide flexibility in managing other forage resources in an integrated system. I evaluated 20 grass‐legume mixtures for use in the northern Rocky Mountain area. Yield contribution of ‘Regar’ meadow bromegrass (Bromus biebersteinii Roem and Schult), ‘Manchar’ smooth bromegrass (Bromus inermus L.), ‘Chinook’ orchardgrass (Dactylis glomerata L.), and ‘Troy’ Kentucky bluegrass (Poa pratensis L.) to grass‐legume mixtures was studied when each was seeded in mixtures with alfalfa (Medicago sativa L.), Ladino clover (Trifolium repens L.), and birdsfoot trefoil (Lotus corniculatus L.) or with sainfoin (Onobrychis viciifolia Scop.) added to each of the latter two. Mixtures were planted in the field into a Bozeman silt loam (Argic‐pachic cryoboroll) soil, grown with adequate irrigation water, and harvested to simulate a frequency similar to that occurring in an irrigated pasture system. Regar meadow bromegrass contributed significantly more to mixture yields than other grasses and alfalfa more than other legumes over the 4‐year period. The two bromegrasses contributed more to yield at the first harvest than orchardgrass or Kentucky bluegrass. Birdsfoot trefoil contributed less than other legumes to mixture yields but sainfoin seeded with birdsfoot trefoil mixtures increased yields to a level equal to that of Ladino clover mixtures. Sainfoin was rapidly lost from mixtures containing Ladino clover. Differences in yield contribution among grasses were least when they were grown with taller‐growing legumes and greatest when grown with shorter‐growing legumes.
Response of Coastal Bermudagrass to Tillage and Fertilizers on an Eroded Grayland Soil1
Authors: Kissel D. E. , Burnett Earl
Published: July 2010

Soils of the Wilson‐Crockett‐Burleson and the Burleson‐Heiden‐Crockett associations in the Blackland and Prairie have poor water relations and low fertility. The result is low crop production in many cases. The poor water relations are caused, in part, by a claypan that is often near the soil surface. The objective of this study was to impose various tillage and fertilizer treatments on a representative low‐producing area of these soils to determine the feasibility of renovation to improve forage production by Coastal bermudagrass (Cynodon dactylon L.). The soil at the experimental site was a Crockett sandy clay loam (Uderic Paleustalf, fine, montmorillonitic, thermic).

The site was chiseled about 15 cm deep with chisels on 1 m centers the first year of the study only. Fertilizer treatments were imposed on the chiseled area and an adjacent area not chiseled. Forage yields were measured. Chiseling increased forage production throughout the study. When N application was 140 kg/ha and greater, forage production from the chiseled site was up to 3.3 times greater than from the area not chiseled. Breaking the claypan probably allowed greater infiltration of rainwater and applied fertilizer, thereby improving the environment for forage production.

On an adjacent area, tilled to a depth of 1.5 m, forage production was the same on deep‐tilled and nontilled areas during the first year of the study. During the second year, forage production was increased by deep‐tillage and increased further when the deep‐tilled areas were treated with gypsum at 11 metric ton/ha.
Effect of Soil Water Potential of Two Soils on Soybean Emergence1
Authors: Heatherly L. G. , Russell W. J.
Published: July 2010

Rapid, uniform emergence of seedlings from the soil is an important factor in crop production. A greenhouse study was conducted to evaluate the effect of different levels of soil water potential on rate and percentage of soybean [Glycine max (L.) Merr.] emergence from two soil types. ‘Tracy’ soybeans were planted in Sharkey clay (Vertic Haplaquept, very fine, montmorillonitic, thermic) and Dubbs silt loam (typic Hapludalf, fine‐silty, mixed thermic) soils equilibrated to soil water potentials (SWP) of −0.1 to −0.7 bar in 0.1 bar increments. Emergence counts were made through 14 days after planting, and each emerging seedling was rated for morphological abnormalities.

Plants emerged from the Sharkey clay at a faster rate and over a wide range of SWP's than from the silt loam soil. Total emergence from the clay soil after 14 days was not significantly different over the range of SWP's used, and exceeded 81% in all treatments. However, significantly fewer plants emerged from the −0.1 and −0.7 bar potentials of the silt loam soil than from the −0.4 to 0.6 bar levels. The range of emergence from the silt loam was 31.7 to 90.0%. The trends for percentage of normal plants that emerged at each SWP level within each soil were the same as those for total emergence.

Based upon these results, rapid and uniform emergence of soybean seedlings can be expected if SWP of a fine‐textured soil such as Sharkey clay is between −0.1 and −0.7 bar and that of a medium‐textured soil, such as Dubbs silt loam is between −0.4 and −0.6 bar. The range is apparently more critical for the latter soil.
Corn Response to S‐Coated and Non‐Coated Superphosphates and Residual Effects1
Authors: Nicholaides J. J. , Fiskell J. G. A. , Martin F. G.
Published: July 2010

Maintaining sufficient available P to crops, including corn (Zea mays L.), has long been recognized as a limiting feature to maximum production in most soils. Providing the P in a pellet should permit soluble P to saturate the soil with P at the pellet while preserving a portion as reserve in the pellet. To test this hypothesis, pelletized ordinary superphosphate (OSP), concentrated superphosphate uncoated (CSP), or coated with S and sealant (SCSP) were compared in a Rhodic Paleudult (a Red Bay, fine, sandy loam), previously uncultivated. This soil was gibbsitic and gave a maximum P sorption of 2,670 kg/P ha and had, at preplant, 11 kg P/ha extractable by 0.03 N NH4F in 0.1 N HC1. The major experiment was a randomized block design with each main plot split for banded and broadcast P placement with the CSP and SCSP compared at 28, 56, 112, and 140 kg P/ha. A secondary experiment compared OSP and SCSP combinations, all broadcast at 84 kg P/ha. The first year, corn cultivar ‘Pioneer 3009B’ was grown. The second year, plots previously receiving broadcast P were refertilized at one‐half the prior P level of CSP and SCSP while plots with banded P received no further P. The third year, no further P was added. The latter 2 years, corn cultivar ‘Pioneer 3369A’ was planted.

Greatest increase in corn grain yield was obtained for the first 28 kg P/ha and further response was linear at 200 kg/ha yield for each additional 28 kg/P applied. Yield response was not significantly different either for P sources or for placement. The second year, residual P from that applied the first year gave linear corn grain yield response which was similar to that found when an additional P fertilization was made. The third year, grain yields gave better response to two, rather than one, annual P fertilization. There was no grain yield advantage to blending OSP and SCSP pellets either in the first or third year. Soil test values and ear leaf P values showed linear responses to rates of applied P.
Seed Germination and Seedling Growth Inhibition Caused by Safflower Seed Extracts1
Authors: Kheradnam M. , Bassiri A.
Published: July 2010

Wild safflower (Carthamus oxyacantha Bieb.), a close relative of cultivated safflower (C. tinctorius L.), is an excellent source of germplasm for adaptability and resistance to diseases and drought. However, its seed germinates poorly even under the most favorable laboratory conditions. Several experiments were conducted to determine the cause of low germination of wild safflower (WS) seed. When seeds (achenes) of WS were rinsed once and immediately germinated, the germination percentage increased by 16% over that of the check. Soaking seeds for 1 day doubled the germination percentage over the controls, and raised it to the viability level of the seed. Aqueous extracts of WS and cultivated safflower (CS) seeds caused dramatic decreases in the germination and seedling growth of WS and lettuce (Lactuca sativa L.) seeds. The WS seed extract, although producing marked decreases in WS seed germination, was ineffective on CS seeds. Toxicity of these extracts was attributed to the high content of ions, salts, or other material which caused high osmotic potentials in the extracts. The boiled extract, although less effective than the unboiled, still produced significant deleterious effects on germination and seedling growth of WS, CS, and lettuce. Extracts from the WS embryos had a more pronounced effect on germination than that of the hulls
Suitability of Sugarbeets for Limited Irrigation in a Semi‐arid Climate1
Authors: Winter S. R.
Published: July 2010

Traditional heavy irrigation of sugarbeets (Beta vulgaris L.) on the Southern High Plains is being questioned because of declining pumping rates and increasing cost of energy for pumping irrigation water. The objective of this work was to determine the suitability of sugarbeets for limited irrigation in a semi‐arid climate. Sugarbeets were flood‐irrigated in level basins enclosed by dikes with water accurately measured onto each plot. Soil was Pullman clay loam (fine, mixed, thermic Torrertic Paleustolls order Mollisols), a very slowly permeable soil representative of the majority of sugarbeet acreage in this region. Irrigation schedules and amounts were varied to produce a wide range of water stress severity, duration, and timing. Weather was typical of this region; erratic precipitation totaled about one‐fourth of pan evaporation, and hot, dry, windy conditions frequently prevailed. Sugarbeets made efficient use of limited rainfall and soil profile water even when subjected to periods of water stress as long as 5 months. Irrigation water was most efficiently used when water application was adequate to maintain a nearly full canopy with no periods of major water stress or excessive water. One irrigation applied prior to onset of major water stress in July promoted high water use efficiency. Sugarbeet response to limited irrigation compares favorably to that of grain sorghum (Sorghum bicolor L.), the major summer crop presently grown on the Southern High Plains with limited irrigation. No unusual production problems have occurred with limited irrigation of sugarbeets. This work indicates that sugarbeets can be efficiently grown under a wide range of irrigation level. Sugarbeets readily adapt to limited irrigation because they utilize deep‐stored soil water and quickly recover growth following major water stress.
Design and Testing of a New Microlysimeter for Leaching Studies1
Authors: Drake R. J. , Pepper I. L. , Johnson G. V. , Kneebone W. R.
Published: July 2010

A new microlysimeter designed to facilitate leaching studies under perched water table situations was constructed of commonly available materials. Advantages of the microlysimeter include low cost, low mortality rate, reliability, small volume, and simple construction. Design of the microlysimeter is shown in this note. The microlysimeter was tested by conducting a leaching study of nitrate through a sand medium. Rates of 0, 35, 70, and 140 kg N/ha as KNO3 were applied to the sand, which subsequently was leached daily with water. Leachate samples were collected and analyzed for NO3‐‐N. Overall mean N recovery was 97.6% for all rates. Coefficient of variation between replicates was 8.5%. Correlation of leached versus expected N gave a correlation coefficient of 0.94. These data indicate that the microlysimeter is a useful and reliable aid for soil leaching studies with perched water tables.
Winter Hardiness in New Digitaria Germplasm1
Authors: Oakes A. J. , Langford W. R. , Schank S. C. , Roush R. D. , Hodges E. M.
Published: July 2010

Portions of the USDA Digitaria collection have been assessed for winter hardiness in previous studies. The objective of this study was to identify additional winter hardy Digitaria germplasm for the purpose of extending its production range as permanent pasture in the southeastern United States. This objective was accomplished by assessing plant survival for winter hardiness of 14 species and two subspecies comprising 230 accessions grown in field trials for 3 years at four locations in Florida and Georgia. Significant differential winter hardiness was exhibited among Digitaria species and among clones within species. Winter hardiness of seven species and two subspecies was significantly superior to that of the remaining seven species. The species of greatest economic value, D. decumbens Stent comprising three cultivars, is among the most winter hardy germplasm. The cultivars ‘Pangola,’ ‘Slenderstem,’ and ‘Transvala’ are among 13 clones which exhibited maximum winter hardiness. The average performance of species masked the superior winter hardiness of individual clones in some instances. These findings substantiate those reported previously and emphasize the consideration that should be given individual clones in the search for, and utilization of winter hardy Digitaria germplasm. The effect of minimum temperature on winter survival was determined. This winter hardy germplasm is being utilized in plant improvement programs, particularly in Florida. These results demonstrate the need for additional field research in an assessment of the elite winter hardy germplasm for adaptation and production capacity.
Effect of Soil Micro‐Relief of a Louisiana Bank System of Field Drainage After Conversion from the Cambered Bed System on Sugar Cane
Authors: Simpson L. A. , Gumbs F. A.
Published: July 2010

In the Caribbean, sugar cane (Saccharum officinarum L.) fields are being converted from Cambered Beds to Louisiana Banks to facilitate mechanization. After conversion the fields often subside particularly in the areas where former drains were located. This subsidence influences field drainage, soil water relations, and sugar yields. The effect of soil micro‐relief on sugar cane growing in the field on Louisiana Banks after conversion from Cambered Beds was studied during the wet season in Trinidad. Three types of topographies: depression, elevated, and sloping areas occurring within a field of the soil type aquic eutropepts, were selected for study.

Areas of soil depression caused mainly by soil subsidence after conversion were found to have significantly higher soil moisture than areas of elevations and were also observed to have ponding water for continual periods during the course of the experiment. The nutrient and moisture levels of the top visible dewlap leaf of 21‐week‐old sugar cane, stalk growth, juice quality, and final yields of sugar cane and sugar measured on plots on the three topographies were used as indices of sugar cane performance. These parameters were found to be significantly affected by areas of soil depressions in the field. Only juice quality was favorably affected during the wet season by the areas of soil depression, as flooding caused premature ripening of canes. This better juice quality was not maintained as the soil dried out and there was no significant difference in juice quality at harvest. Losses in sugar cane and sugar yields from areas of soil depression compared with elevated and sloping areas varied between 41 and 47%. It is therefore recommended that allowances be made for soil subsidence and that more precise grading and land smoothing operations be carried out when fields are converted from Cambered Beds to Louisiana Banks.
Yield and Agronomic Characteristics of Meadowfoam With Planting Dates and Rates1
Authors: Johnson J. W. , Devine M. B. , White G. A. , Kleiman R.
Published: July 2010

Information concerning the cultural practices of meadowfoam Limnanthes alba Benth.), a potential seed oil source of long chain fatty acids, is limited. The effects of date and rate of planting on seed yield and weight, oil production, date of flowering, winter survival, seed shattering, and plant erectness in meadowfoam were studied in the field in 1974 and 1975. Three plant introductions were sown in Queenstown, Maryland on four dates between 21 September and 6 November and at four planting rates (11, 17, 23, and 29 kg/ha).

Maximum seed yields resulted following early to mid October planting and from a planting rate of at least 23 kg/ha. In 1974, a year of below‐average winter temperatures, seed yields ranged from 507 to 739 kg/ha at the planting rates of 11 and 29 kg/ha, respectively. The winter survival of the plots also increased as the planting rate was increased. In 1975, a year of above‐average winter temperatures, no differences between the planting rates for yield or winter survival were detected. Planting rates did not affect oil content or seed weight. However, planting dates caused considerable amount of variation for these characteristics. Planting rates had no effect on date of flowering, plant erectness, or seed shattering.

P.I. 374790 averaged 22 and 12% more seed yield than P.I. 283701 and P.I. 374791, respectively, but produced 5%, lighter seed than the other entires. The heaviest seed was produced by P.I. 283701 which also had the highest oil content (27%). The correlation between oil content and seed weight was 0.67 (P=0.01) in 1975. Under Maryland conditions, meadowfoam should be planted in early to mid‐October at a rate of 23 kg/ha to obtain maximum yield and to avoid winter injury.
Evaluation of Commercial Soybean Inoculants from South Carolina and Georgia1
Authors: Skipper H. D. , Palmer J. H. , Giddens J. E. , Woodruff J. M.
Published: July 2010

Since poor quality inoculants could be one of the factors responsible for nodulation failures in soybeans [Glycine max (L.) Merr.], 93 planter‐box inocultants from commercial retail sources in South Carolina and Georgia were evaluated for numbers of viable Rhizobium japonicum on yeast extract mannitol agar. Spread plates were counted after incubation for 7 days at 28 C Two sub‐samples from each commercial inocultant were evaluated. Viable rhizobial counts ranged from 6.9 × 109 to ≤ 1.0 × 103/g of inoculant. Statistical differences were detected among brands. Inoculants which contained a fungicide and/or Mo were consistently and significantly lower in viable rhizobia than other brands. The low viable rhizobial counts were also reflected in poor nodulation of soybean roots under greenhouse conditions. A highly significant correlation was obtained between the log of viable rhizobia and the number of nodules per plant for 27 inoculants. Plate counts provided a relatively rapid and inexpensive method to assess the quality of commercial inoculants.
Residual Activity of Herbicide Treatments on Bermudagrass Greens Overseeded with Ryegrass1
Authors: Johnson B. J.
Published: July 2010

Goosegrass [Eleusine indica (L.) Gaertn.] control is a major problem weed in bermudagrass [Cynodon dactylon (L.) Pers.] putting greens and it is usually necessary to apply postemergence herbicide treatments throughout summer and early fall for effective control. Since bermudagrass greens are overseeded with cool‐season grasses in early fall, a study was conducted on a Cecil (Typic Hapludult) sandy loam at Experiment, Ga. to determine the interval needed between Herbicide treatments and time of overseeding without injuring the newly planted turf.

A ‘Tifway’ bermudagrass putting green was treated with MSMA (monosodium methanearsonate), methazole [2‐(3,4‐dichlorophenyl)‐4‐methyl‐l,2,4‐oxadiazolidine‐3,5‐dione], metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazin‐ 5(4H)‐one] and combinations of MSMA with either methazole or methribuzin at 0, 1, 2, 4, and 6 weeks before overseeding with perennial ryegrass (Lolium perenne L. ‘Medalist IV’ and ‘Medalist V’). Methazole applied alone was the only herbicide that required at least 1 week between treatment and overseeding without affecting the stand of newly planted turf. Metribuzin applied on day of overseeding significantly reduced seedling vigor but not turf stand. Combinations of MSMA with either methazole or metribuzin did not affect growth of ryegrass when applied anytime up to the day of overseeding.
Effect of Fertilizer Reaction and Placement on Availability of Manganese1
Authors: Voth R. D. , Christenson D. R.
Published: July 2010

Manganese deficiencies are a serious problem in crop production on some high pH soils of the lake bed regions of Michigan and Ohio. It has been observed that some fertilizers banded near the seed increase Mn availability. Several factors have been suggested to be responsible for this increased availability. A series of laboratory incubation, greenhouse, and field studies were conducted to evaluate fertilizer reaction and Mn sources on availability of Mn to sugarbeets (Beta vulgaris L.), soybeans (Glycine max L.) and navy beans (Phaseolus vulgaris L.).

The incubation study showed that fertilizer sources which produce an acidic reaction initially increase the level of DTPA (diethylenetriaminepenta‐acetic acid) and 0.1 N H3PO4 extractable Mn in the soil contiguous to the fertilizer band. After seven weeks of incubation, H3PO4 extractable Mn levels were not significantly different for the various fertilizer treatments. The level of Mn extracted with DTPA after seven weeks for the fertilizer sources was: DAP‐Urea‐KCl > control = MAP‐Urea‐KCl > NH4NO3‐MCP‐KCl = (NH4)2SO4‐MCP‐KCl, where DAP = diammonium phosphate, MAP = monoammonium phosphate and MCP = monocalcium phosphate.

The greenhouse study was conducted on a Tappan loam (Typic Haplaquepts) and consisted of a 24 factorial set of treatments with N sources of urea and (NH4)2SO4; N and P (MCP) placements of mixed and banded; and Mn levels of banded Mn and no Mn. Banded MCP proved to be as effective as banded Mn in increasing Mn availability (extractable and plant uptake). Banded Mn along with banded MCP proved to be much superior to either factor alone. Nitrogen source and placement had small and variable affects on Mn availability and were largely masked by the Mn and P placement treatments.

Field studies were conducted on seven soil types to test the effect of fertilizer and Mn sources and showed the following order of tissue Mn: MnSO4 = MnO (100 mesh) > oxysulfate (partially acidulated MnO) = Mn‐EDTA = control. Tissue samples taken within five weeks of planting had higher Mn concentration for a NH4NO3‐MCP‐KCl (acidic) fertilizer than for the urea‐DAP‐KCl (basic) fertilizer. However, when oxidation of the NH4‐N in the basic fertilizer was more complete, the difference diminished. The results suggest that when Mn deficiencies occur early in the growing season, use of an acidic fertilizer in combination with MnSO4 or finely divided MnO would be helpful in elimination of the problem.
Cotton Production Affected by Row Profile and N Rates1
Authors: Harris C. H. , Smith C. Wayne
Published: July 2010

Cotton (Gossypium hirsutum L.) production in the Delta of Arkansas requires 150+ days from planting to final harvest. The evolved system for growing cotton includes planting on raised beds with N applied preplant into or under the bed. Maturity delays and associated yield reductions in recent years may have been related to this system. A study was initiated in 1975 to compare four genotypes grown in flat or bedded seedbeds with twice the recommended rate of N and half the recommended rate in order to evaluate the role of salts on seedcotton yield and earliness. The four genotypes represented a range of genetic maturity. A split‐block, split‐plot arrangement of a randomized complete block was utilized and the test site was Calloway silt loam, a fine‐silty mixed, thermic alfisol, located on the Cotton Branch Experiment Station, Marianna, Ark.

Observations confirmed the surface drainage advantage of raised seedbeds. Otherwise, row profile contrasts had no effect on yield during any year, and we found no evidence that nitrate salts became concentrated in raised seedbeds, discounting the suggestion that increase in these salts resulted from the raised beds and thus directly delayed maturity.

The 134 kg/ha rate of N resulted in higher seedcotton yields than did 34 kg/ha but also delayed maturity as indicated by percent first pick, regardless of row profile. Aborted terminals were shown not to be the cause of delayed maturity with the high rate of N. Genotypes responded to the effects of contour and N equally as indicated by the lack of significant interactions.
Salinity, Irrigation Frequency, and Fertilization Effects on Barley Growth1
Authors: Wagenet R. J. , Campbell W. F. , Bamatraf A. M. , Turner D. L.
Published: July 2010

The response of a grain crop to yield variables such as salinity, soil fertility and irrigation often depends upon the integrated and simultaneous effects of these factors. A greenhouse study was therefore conducted to investigate the interactive effects of water salinity, N and P fertilization, and irrigation scheduling on barley (Hordeum vulgare L.). Three water salinity levels, four N fertilization rates, three P fertilization rates, and three frequencies of water application were imposed on a nonsaline, nongypsiferous, silty clay loam soil (aquic ustifluvent). Dry matter and grain yields, and several yield components were measured. Dry matter and grain yields were reduced with decreasing irrigation frequency (2 to 8 days) and increasing salinity of irrigation water (0.5 to 13.5 mmho/cm). Nitrogen fertilization did not produce greater salt tolerance, and resulted in reduced yield by promotion of tillering at the expense of grain filling. Neither dry matter nor grain yield changed appreciably with increasing P fertilization. Increases in dry matter and grain yield were associated with decreases in the leaching fraction (LF) to a certain limit, then yield declined as LF decreased. The salinity of the soil extract increased noticeably as irrigation water salinity increased. However, frequent irrigation prevented salt buildup.
Labeled Nitrogen Uptake by Drip‐Irrigated Tomatoes1
Authors: Miller R. J. , Rolston D. E. , Rauschkolb R. S. , Wolfe D. W.
Published: July 2010

In order to evaluate the availability of fertilizer N applied by drip irrigation, tomatoes (Lycopersicum esculentum Mill.) were grown in the field for two years on Panoche clay loam (Typic Torriorthents). Labeled fertilizer was banded in the soil and furrow or drip irrigated as well as applied through the drip system to measure the effect of different placements and timing on fertilizer N availability. Some treatments received N only at planting while others received split applications through the drip system at different stages of plant development. Nitrogen (15N depleted) was applied to the center harvest rows while commercial (0.36%15N) ammonium sulfate was applied to the outside rows of each plot. Plants from the center harvest rows were analyzed for total N and isotopic composition. Plant analyses indicated that treatments in which fertilizer N was applied through the drip system, regardless of timing or growth stage, showed higher percent fertilizer N contents during most of the growing season than those of the furrow‐irrigated treatments. The greatest amount of fertilizer N in the plant at any sampling time was 40 to 50% of the total plant N. Only small differences in total tomato yields were observed among treatments, although drip‐applied did appear to enhance tomato fruit maturity. For high efficiency, fertilizer N should be placed carefully with respect to plant roots, taking into consideration the direction of water movement during irrigations.
Soybean Root Morphology and K Uptake1
Authors: Peterson W. R. , Barber S. A.
Published: July 2010

When roots are grown in media of high mechanical strength, such as in sand rather than solution, root diameter increases. Little is known of how root morphology affects nutrient influx. The objective of this research was to determine if changes in root morphology created by changing growth media affected K influx into the root. Soybean (Glycine max L. Merr.) plants were grown in solution culture and in sand continuously leached with nutrient solution. Both were in a controlled climate chamber. Shoot weights were similar for both treatments. Root weight per pot and root radius were greater )(0.22 vs. 0.17 mm) for sand‐grown plants than for solution grown plants. Root lengths per pot were similar. Increased root radius was due to an increase in radial size of the cortical cells. Radius of the stele was not affected by treatment nor was number of cortical cells in a cross‐section of the root. Imax (maximum influx) for K influx was 55% greater for sandgrown roots than for solutiongrown roots. The Michaelis constant (Km) and the level of K in solution where net K influx was zero (Cmin) were not influenced by treatment. Soybeans had greater root weight when the roots encountered adverse growing conditions. When the data for increased root radius and Imax were used in a mathematical model to predict K uptake, increasing r, from 0.17 to 0.22 mm increased predicted uptake 21% and increasing Imax from 4.6 to 7.1 pmoles cm−2Sec−1 increased predicted uptake 35%.
Daily Patterns of Apparent Photosynthesis and Evapotranspiration in a Developing Winter Wheat Crop1
Authors: Johnson R. C. , Witters R. E. , Ciha A. J.
Published: July 2010

High temperatures strongly influence apparent photosynthesis (AP), evapotranspiration (ET), and leaf area index (LAI) of winter wheat (Triticum aestivum L.) in semi‐arid regions. Our objectives were to relate temperature and short‐wave solar radiation (SR) to crop AP, ET, and LAI in a field environment. Two aluminum frame chambers covered with mylar plastic and occupying 0.74 m2 of soil surface area were used with infrared gas analyzers to measure AP and ET on ‘Wanser’ winter wheat grown in Ritzville silt loam (Mesic Calciorthidic Haploxerolls). Calculations of AP and ET were made from the respective differences between chamber intake and exhaust CO2 and H2O concentrations.

On clear, high SR days, maximum AP declined from 4.2 to 2.9 g CO2m−2hour−1 from stem extension through the watery ripe developmental stage. During that same period, maximum daily ET ranged between 440 and 600 g H2O m−2 hour−1, but did not decline as LAI declined from 2.0 to 1.1. A midday reduction in AP was observed when leaf temperatures (TL) approached 25 C corresponding to high daily values of ET and SR at anthesis, water ripe, and milky ripe stages. Since measurements of ET were over dry soil and assumed to represent plant transpiration, substantial stomatal closure was apparently not responsible for the decline in AP on those days because a concomitant reduction in ET was not always observed. Temperatures that were above optimal for AP most likely caused the midday decline in AP. This interpretation was consistent with water use efficiency (WUE) values, expressed as AP/ET, which were lowest at midday and generally declined as the crop matured.

Total daily AP from heading through anthesis (15 days) on clear and partly cloudy days did not decline appreciably (ranging from 30.5 to 32.4 g CO2 m−21 day−1) even though LAI declined 17% during that period. On clear days, high ET was associated with high SR and high temperatures. Temperatures tended to depress AP so that WUE was greater on partly cloudy and overcast days than on clear days at a given developmental stage. Under the climatic conditions of this study, WUE could be increased with early maturing cultivars that avoid the high late season heat load commonly associated with wheat production in this region.
Selection of Concomitant Variates Affecting Regrowth, Yield, and Digestibility in Forage Sorghums1
Authors: Fribourg Henry A. , Creel Rodney J.
Published: July 2010

Numerous environmental factors and plant characteristics, and interactions among them and with management practices, affect growth and composition of summer annual forage sorghums (Sorghum bicolor (L.) Moench). Thirty‐eight plant and environment characteristics were estimated concurrently with the dry matter (DM) yield, DM regrowth rate (DM yield/day since emergence or since preceding harvest), and in vitro dry matter digestibility of three cultivars grown in the field on a fine‐loamy, siliceous, thermic Humic Hapludults and subjected to 19 different defoliation regimes in 2 different years. The selection of a subset of the 38 observed concomitant variates could be useful for planning future research. The purpose of this paper is to report on the sequential use of factor analysis and multiple regression techniques to decrease the number of independent variables without appreciable loss in the explanation for variability in the dependent variables. Factor analysis was used first to reduce possibly redundant concomitant variables or select proxy variables for a whole dimension. Fifteen of the original 38 variates were selected. multiple regression was then used to reduce further the concomitant variables to nine variables (days of growth since planting, days of regrowth since previous harvest, height of standing crop, leaf area index (LAI) of whole plant, DM yield of stubble at previous harvest, cumulative precipitation, degree days since previous harvest, percent leaf in DM harvest, LAI of whole plant at previous harvest). Six or fewer of these variates were associated with a large portion of the variability in the three dependent variables.

The goal of parsimoniously identifying the variables which affected the dependent variables within a genotype in these experiments was attained. The strategy employed—sequential use of factor analysis and multiple regression for reduction in number of concomitant variables—may have merit for investigations in many agronomic disciplines.
Predicting Cotton Crop Boll Development1
Authors: Wanjura D. F. , Newton O. H.
Published: July 2010

Cotton (Gossypium hirsutum L.) lint development on the Texas High Plains frequently spans periods of low temperature that reduce yield and quality. We conducted a study in 1977 to 1979 at Lubbock, Texas, to develop a procedure for estimating the level of crop lint maturity at any time after boll setting begins.

The procedure includes a model that uses the initiation date for each 1/10 increment of the total crop of bolls and average daily air temperatures. Data generated by the estimating procedure were compared with data on observed crop lint development in the cultivars ‘Paymaster 303’, ‘Paymaster 909’, and ‘Acala 3080’. The observed data were obtained by tagging all blooms initiated by plants in two 3‐m row lengths of each cultivar and measuring boll periods of the permanent bolls.

The procedure produced accurate timely estimates for crop lint development and boll opening rate for all cultivars in 1977 and 1978. Observed boll periods in all cultivars were 15% shorter than estimates for the entire crop of bolls in 1979. A likely explanation for the shortened boll periods was that 1979 plants required 2 weeks longer to reach first bloom than 1977 and 1978 plants and were physiologically older. Other researchers have also reported reduced boll periods in “old” cotton plants.
Reflectance Differences Between Target and Torch Rape Cultivars1
Authors: Gausman H. W. , Leamer R. W.
Published: July 2010

To characterize and explain leaf and plant reflectance differences between Target (Brassica napus L.) and Torch (Brassica campestris L.) rape cultivars, laboratory spectrophotometric reflectance measurements were made on leaves of the same age, collected from different nodes, and on leaves of different ages, collected from the same node, for both small (five leaves) and large (nine leaves) Target and Torch plants. Spectroradiometric reflectance measurements were made on Target and Torch plants (four and five leaves, respectively) that were growing in 0.09 m2 soil‐containing flats. Torch's spectrophotometric single leaf reflectance was consistently lower than Target's at the 650‐nm chlorophyll absorption band because Torch's chlorophyll concentration was larger than Target's, which caused more red light absorptance. Spectroradiometric measurements indicated that: (1) wet soil strongly absorbed visible light (500 to 700 nm) so that Target's soil‐containing flat with 60% plant cover had less reflectance than Torch's soil‐containing flat with 75% plant cover, (2) Torch (most foliage) had higher near‐infrared (750 to 1,350 nm) reflectance than Target (least foliage), and (3) the 2,200‐nm wavelength is a candidate band to distinguish Target from Torch. The difference in chlorophyll concentrations between Target and Torch, compared with leaf structural differences, is apparently the most important factor that would affect the infrared color film's tonal response to vegetation in the photographic sensitive region (500 to 900 nm).