bluuebunny/crossref_metadata_2025_split huggingface dataset:
Single‐Cross Bermudagrass Seed Production under Different Management1
Authors: Ahring R. M. , Taliaferro C. M. , Richardson W. L. 
Published: July 2010

AbstractThe ease with which bermudagrass [Cynodon dactylon (L.) Pers.] plants are vegetatively propagated, combined with their usual high degree of sexual self‐incompatibility, provides a simple mechanism for producing single‐cross seed. Such seed could be produced using two cross‐compatible, self‐incompatible plants vegetatively propagated in alternate rows in a production field. The feasibility of the system depends firstly on the seed yield potential of the parental plants and secondly on the acceptability of the hybrid plant population. This experiment was conducted to measure single‐cross seed yields and seed yield components from such a production block, as influenced by N fertilization and early‐season forage removal.The cross‐compatible, self‐incompatible bermudagrass plants were Oklahoma Agric. Exp. Stn. accessions ‘A‐9959’ (PI 253302) and ‘Guymon’. Four levels of N fertilization (N = 22, 34, 67, and 101 kg/ha) and two spring mowing treatments were used in each of the 3 years of the experiment. The experimental design was a Latin Square, split‐block, replicated four times. The soil was a Brewer clay loam (fine, mixed, thermic Pachic Arguistolls). The mowing treatments consisted of mowing and removing all growth on or about 1 May (Management A) or mowing and removing all growth on or about 1 May and again on about 20 May (Management B). Nitrogen fertilizer was applied at the selected rates in single annual applications soon after the plots were mowed on or about 1 May. Seed yield (kg/ha) and seedhead density (seedheads/m2) were measured for 3 years (1975–1977), and florets/raceme and % seed set were measured for 2 years.Seed yields (kg/ha) averaged over treatments ranged from 658 in 1975 to 818 in 1976 and had a 3‐year average of 743. Nitrogen fertilizer rates had no significant (P > 0.05) or discernible effect on any of the response variables. Significant effects due to management occurred for seed yield (P < 0.05) and seedheads/m2 (P < 0.05) in 1975 and for florets/raceme (P < 0.01) in 1976. Differences attributable to years were significant (P < 0.01) for seed yield and seedheads/m2. The only significant interaction was management x years for seedheads/m2 (P < 0.05). Seed yields were higher under Management A during each year of the experiment, though the difference was significant only in 1975. Management A plots had significantly more seedheads/m2 than Management B plots in 1975, but slightly fewer in 1976 and 1977. Management A plots also bore racemes with significantly more florets in 1976.While the elucidation of management effects on bermudagrass seed production will require further experiments conducted over time, our results support the feasibility of using presently available germplasm to produce new single‐cross seed propagated cultivars.
Availability of Rock Phosphate as Measured by an Acid Tolerant Pasture Grass and Extractable Phosphorus1
Authors: Yost R. S. , Naderman G. C. , Kamprath E. J. , Lobato E. 
Published: July 2010

AbstractAs agricultural development intensifies in tropical countries and as costs of superphosphate production increase, the need for further evaluation of rock phosphates has become apparent. An acid tolerant pasture grass (Brachiaria decumbens Stapf.) was used to evaluate the initial and residual (3 years) availability of P from several phosphate materials. A field study was conducted on a Typic Haplustox of the Cerrado of Central Brazil. Initial availability of P supplied as normal superphosphate, Hyperphosphate, Thermalphosphate, and North Carolina rock phosphate was similar when the soils were not limed (pH = 4.3, Al = 1.4 meq/100g). Where lime had been added and pH was increased to 5.4 the P in Hyperphosphate and N.C. rock phosphate was initially less available than P added as superphosphate and Thermalphosphate. After 10 months of contact, lime no longer significantly depressed P availability in these relatively soluble rock phosphates as measured by forage dry weight. The P in the other phosphate rock of low citric acid solubility, Araxá, was virtually unavailable during the 3 months after application. However, within 13 months, maximum forage yields were attained where this material had been applied to unlimed soil and at 25 months maximum yields were obtained on both limed and unlimed soil. Higher rates of Araxá material were required to obtain maximum yields than with normal superphosphate. Forage yields were 2 to 4 times greater where superphosphate was surface applied each year than where similar amounts were incorporated prior to planting. A comparison of extractant methods for soil P indicated that highly acidic extractants (e.g., 0.05 N HC1 + 0.025 N H2SO4) overestimated available P where rock phosphate had been applied. Where superphosphate or rock phosphate had been applied, P availability was better assessed by extractants such as 0.5 M NaHCO3 and Bray 1. The results emphasize the need to supplement laboratory and short‐term studies with long‐term evaluations of P materials with acid tolerant perennial crop species available in tropical countries.
Effect of Amendments on Microhydrologic Properties of Compact Basal Till Soil and Yield of Alfalfa1
Authors: Chow T. L. , Saini G. R. 
Published: July 2010

AbstractGreenhouse and field experiments were conducted to evaluate the efficacy of various amendments (lime, farm manure, and sawdust), alone and in combination, for improving hydrologic properties of a dense basal till soil (Fera Luvic Gleysol in the Canadian system of classification which is equivalent to Typic Ochraqualf in the U.S. system) and for increasing alfalfa (Medicago sativa L.) yield.The amendments used in the experiments were mixed with sub‐soil samples fragmented to < 5 mm at a rate of 16 g/kg of sub‐soil on a dry basis and packed into PVC columns in which minature ceramic cups at various depths were installed to measure soil water matric potential during the growth period of crop planted in the columns. After the harvest of the crop the columns were used to determine bulk density and various hydrological properties of the soil.The hydrological data of the soil indicated that the saturated hydraulic conductivity of sawdust‐treated sub‐soil was six times higher than the manure treatment and over 53 times higher than the control. Moisture retention curves suggested that an increase in percentage of pores > 29 micron was the major difference in pore size distribution between the organic matter treated and the nontreated sub‐soils.The greenhouse, as well as the field experiments, showed that all organic amendment treatments gave significantly higher yields than the compacted and loosened sub‐soils but were not significantly different from each other. The increase in yield was much more pronounced in the field experiments as compared to the greenhouse ones. It was concluded from these experiments that the incorporation of farm manure and sawdust in the dense subsoils of basal till Fera Luvic Gleysols will improve their physical properties and hence the yield of alfalfa.
Dinitrogen Fixation Measured by 15N Isotope Dilution in Two Canadian Soybean Cultivars1
Authors: Rennie R. J. , Dubetz S. , Bole J. B. , Muendel H.-H. 
Published: July 2010

AbstractAdapted cultivars must be developed if significant production of soybeans [Glycine max (L.) Merr.] is to be realized in western Canada. Selection and breeding for ability to support symbiotic N2 fixation is important in this development.15N isotope dilution techniques were used to determine the percent plant N derived from the atmosphere (%Ndfa), i.e., fixation, and actual amounts of N fixed by two promising cultivars, X005 and Maple Presto. Precent Ndfa for the two cultivars was almost identical under comparable conditions. Depending on soil type and plant growth stage, %Ndfa varied from 38 to 70% in lysimeter experiments and maximized at 67% in the field. X005 fixed significantly more N2 (115 kg N/ha) than Maple Presto (82 kg N/ha) in the field because X005 had a higher N yield, possibly due to a slightly longer growing season. The N yield of both cultivars, when inoculated, did not respond to increasing rates of fertilizer N [Ca (NO3)2]. The highest percent fertilizer use efficiency (%FUE) was 51% when uninoculated and 44% when the seed was inoculated. Although N2 fixation occurred in both cultivars when fertilizer up to 160 kg N/ha was provided, the cultivars differed in their tolerance to fertilizer N with respect to N2 fixation. For X005, N2 fixation was constant as N fertilizer increased from 0 to 80 kg/ha but decreased by 24% where 160 kg N/ha was applied. For Maple Presto, N2 fixation was constant as N fertilizer increased from 0 to 40 kg/ha but decreased by 21% where 80 or 160 kg N/ha was applied. Both cultivars had similar %Ndfa and amount of N fixed/ha to soybeans in other countries.
Prediction of Wheat Grain Protein Content from Climatic and Edaphic Variables1
Authors: Porter Michael A. , Paulsen Gary M. , Feyerherm Arlin M. , Milliken George M. 
Published: July 2010

AbstractGrain protein in wheat (Triticum aestivum L.) has important funtional and nutritional roles and methods to predict its content would be valuable to both producers and users. We developed statistical models to predict grain protein content of hard red winter wheat from soil fertility conditions during anthesis and climatic conditions during grain filling. Soil and grain samples were collected from two irrigated field locations and nine dryland field locations containing 12 wheat cultivars during three growing seasons. A number of models were constructed using SAS procedures. In the best model, five edaphic parameters—P, K, and nitrate concentration from 15 to 46 cm in the profile and organic matter contents from 0 to 15 cm and 15 to 46 cm in the profile—significantly predicted the response surface. There were significant location, year, and location × year effects, but climatic variables did not significantly affect the prediction surface in the set of experiments. The model can be used to predict wheat grain protein content, to identify factors that influence protein content, and to aid in managing wheat for higher protein content.
Second‐Brood Southwestern Corn Borer Infestation Levels and Their Effect on Corn1
Authors: Williams W. Paul , Davis Frank M. , Scott Gene E. 
Published: July 2010

AbstractThe southwestern corn borer, Diatraea grandiosella (Dyar), is recognized as a serious pest of corn, Zea mays L.; however, no data relating level of second‐brood southwestern corn borer infestation of corn and the resulting damage have been reported. To determine the effects of varying levels of second‐brood southwestern corn borer infestation, corn plants were infested at anthesis with 0 to 35 southwestern corn borer eggs in a field study grown at Mississippi State, Miss, on a Leeper silty clay loam (fine, montmorillonitic, nonacid, thermic, Vertic Haplaquepts) in 1974, 1976, and 1977. Grain yields were measured and stalks were dissected after harvest to determine the extent of tunneling. Infestations with increasing numbers of southwestern corn borer eggs were accompanied by a linear decline in yield. A quadratic type curve best described the relationship between number of eggs and number of tunnels in a plant and between number of eggs and extent of stalk tunneling. Damage sustained by corn plants infested with 25 to 35 eggs was heavy and differences among treatments were slight. These results indicate that investigators involved in the evaluation of corn genotypes for southwestern corn borer damage should consider applying approximately 30 eggs per plant in order to achieve a uniform, heavy infestation.
Phosphorus Fertilization and Sugar Yields of Fall Planted Sugarbeets1
Authors: Abbott J. L. , Nelson J. M. 
Published: July 2010

AbstractFall planted sugarbeets (Beta vulgaris L.) are commonly subjected to low winter soil temperatures which contribute to low available soil P. Two field experiments were conducted near Phoenix, Ariz. to determine the effects of P fertilizer and feedlot manure on residual available P and sugarbeet production. Sugarbeets grown on a Laveen clay loam (Coarseloamy, mixed, hyperthermic Typic Calciorthid) soil that had not received P fertilizer for 10 years were compared with those grown on the same soil that had received annual applications of P fertilizer prior to that crop. The effect of residual P was studied at four levels of N (0 to 300 kg N ha‐1). Another experiment on the same soil type evaluated residual P from manure applied at rates of 22,45, and 67 Mg ha‐1 two seasons prior to that crop. Maintaining a high level of residual P by applying P fertilizer to other crops in the rotation was an effective method of avoiding P deficiency in sugarbeets. Both sucrose concentration and sugar yield were influenced by high residual soil P. Soluble P measurements in petioles collected when soils were cold were generally related to sucrose concentration. Winter month soil temperatures as low as 6 C were observed in the Phoenix area. Sugarbeets responded equally to P fertilized soil relatively high in residual soil P compared with soil having residual P from feedlot manure with P fertilizer applied 2 Years earlier.
Tillage and Cultural Management of Irrigated Potatoes1
Authors: Buxton D. R. , Zalewski J. C. 
Published: July 2010

AbstractMany intensively row‐cropped, irrigated soils are compacted and have slow water infiltration rates. This study was conducted to evaluate the relationship among soil compaction, water infiltration rates, and potato (Solanum tuberosum L.) yield and quality; and to determine the influence of tillage and other practices on soil compaction, water infiltration rates, and potato response. Twenty‐two commercial, irrigated potato fields were monitored and several tillage practices evaluated on soils from seven great groups. Soil compaction was evaluated by measuring penetrometer resistance. Although penetrometer resistance and water infiltration rates showed a large amount of variation in the 22 fields, they were not significantly correlated with each other. The correlation coefficient between penetrometer resistance 0.2 m below furrows and tuber yield was −0.38. Water infiltration rate was not associated with tuber yield nor quality. In the 18 fields with less than 600 g kg−1 sand, soil texture had little association with water infiltration rates, however, soil organic matter greater than 12 g kg−1 was positively associated with water infiltration rates. In the 22 fields, number of years between successive potato crops accounted for 33% of the variation in tuber yield with greatest yields when at least 4 years occurred between potato crops. In replicated tillage experiments, chiseling reduced penetrometer resistance to a deeper depth than moldboard plowing. Chiseling did not result in greater water infiltration rates, tuber yield, nor tuber quality than plowing. Chiseling and plowing in combination showed no advantage over either practice alone. Additionally, chiseling bed centers showed no yield advantage over an unchiseled check in fields that were previously plowed even though penetrometer resistance was reduced by chiseling. This study indicates that with proper irrigation management some deep tillage operations can be eliminated by many growers.
A Controlled Environment System for Turfgrass Research1
Authors: Augustin B. J. , Karnok K. J. 
Published: July 2010

AbstractA need exists for a system capable of providing a realistic and controlled environment for conducting research on turfgrass swards. Therefore a controlled environment system was constructed for evaluating the morphological and physiological responses of turfgrass swards to laboratory controlled environmental conditions. The system consists of three basic components: (1) An acrylic plastic assimilation cell which covers a 1,000 cm2 sward of turf, (2) a four‐sided, glass root observation cell, and (3) an open gas exchange system with accompanying instrumentation. The system has the capability of controlled light intensity, light quality, daylength, diurnal air temperature, soil temperature, and relative humidity. The design of the facility allows continuous and concurrent monitoring of both morphological (shoots and roots) and physiological (photosynthesis, dark respiration, and evapotranspiration) responses of turfgrasses to a variety of laboratory simulated environmental conditions.
Use of Box‐Cox Transformation Technique for Fitting Crop Yield Trends
Authors: Lin Kuang‐Hsing T. , Huang Chung‐Liang 
Published: July 2010

AbstractThere is a need for a more general approach to selecting appropriate models for transformation of long‐term crop yield data prior to statistical analysis without a priori restrictions about the mathematical form of the model. A least restrictive formulation about the functional specification of a model is less likely to lead to erroneous results. The objective of the study is to illustrate a general approach to model selection via application of the Box‐Cox transformation technique to estimate national yield trends for corn (Zea mays L.), wheat (Triticum aestivum L.), and soybean [Glycine max (L.) Merr.] during the period 1960‐1979. Results suggest that corn and wheat yields were approaching a plateau level whereas soybeans showed no indication of levelling off of yields.
Device for Removing Mini – Rhizotrons from the Field1
Authors: McMichael B. L. , Brashears A. D. 
Published: July 2010

AbstractMini‐rhizotrons (glass or acrylic tubes) are gaining widespread usage as an acceptable means for observing in situ plant root growth under field conditions. These transparent tubes are placed in the soil to various depths, and roots growing against the surface of the tube are observed throughout the season. It is difficult to remove intact mini‐rhizotrons from the field for reuse to reduce cost because close contact between the soil and glass surface must be maintained. An inexpensive extraction device for the removal of mini‐rhizotrons with minimum breakage or marring of the surface is described. The unit consists of a shaft to which an expandable, spring‐loaded foot mechanism is attached. Foot plates expand and engage the bottom edge of the mini‐rhizotron tube after the foot mechanism is lowered to the bottom of the tube. A tractor lift or other suitable hydraulic lifting apparatus is then attached to the other end of the rod and the tube is lifted out intact. Modifications of the device to accommodate tubes of different sizes and lengths and to assure that the inner surface of the tube is not scratched by the device are discussed.
Central Appalachian Hill Land Pasture Evaluation Using Cows and Calves. III. Treatment Comparisons of per Animal and Hectare Responses1
Authors: Burns J. C. , Harvey R. W. , Giesbrecht F. G. , Cope W. A. , Linnerud A. C. 
Published: July 2010

AbstractThe productivity of hill land pastures using cow‐calf testers in formal grazing trials is not well documented. This study determined animal response and per hectare productivity of improved hill land pasture [mainly Kentucky bluegrass (Poa pratensis L.), and white clover (Trifoolium repens L.)], crownvetch (Coronilla varia L.), and birdsfoot trefoil (Lotus corniculatus L.) subjected to various pasture and animal management treatments during 6 years of evaluation. Soils ranged from primarily a fine loamy micaceous mesic, Typic Hapludult on the uplands to primarily a fine loamy mixed mesic Hapludult in the low lands. Treatments evaluated in April through June (period 1) consisted of N rates (0, 67, 112, and 224 kg ha−1) and continuously grazed crownvetch. From July through October (period 2) two additional legume rotational treatments and early weaning (0, 67, or 112 kg of N ha−1) were evaluated. Cow and calf daily gain (kg), calf gain (kg ha−1), and total digestible nutrients (TDN) (kg ha−1) from improved hill land pasture (IHP) in period 1 averaged 0.74, 0.97, 156, and 1470, respectively. The respective values for period 2 were 0.13, 0.72, 97, and 1100 and for the season were 0.44, 0.84, 245, and 2420. Cow‐calf units were stocked on IHP to average 2.11 ha−1 in period 1, 1.29 in period 2 and 1.54 for the grazing season. Continuous grazing of crownvetch compared with IHP during periods 1 and 2 or rotational grazing of crownvetch and birdsfoot trefoil in period 2 increased only cow daily gain. Calf daily gain in period 1 declined linearly with N rates while calf gain (kg ha−1) and stocking rate increased at a declining rate (quadratic term) at the higher N levels. Maximum calf gain ha−1 occurred at the 224 kg N rate, averaging 109 kg when pastures were stocked at 1.90 cow‐calf units ha−1. Calf gain ha−1 was not altered in period 2 by N rates while stocking rate increased linearly. Pasture productivity was increased by N rate in both periods 1 and 2 with 1 kg of applied N ha−1 yielding 2.47 kg of TDN ha−1 (Ŷ = 1507 + 2.47 X) in period 1 and 1.83 kg of TDN ha−1 (Ŷ = 1109 + 1.83 X) in period 2. Early weaning increased calf daily gain, calf gain and TDN ha−1 compared with conventional grazing, but calf daily gains were variable and less than expected.
Cowpea Response to Row Width, Density, and Irrigation1
Authors: Herbert S. J. , Baggerman F. D. 
Published: July 2010

AbstractThe interrelationships among row width, plant density, and irrigation are not well understood for cowpea [Vigna unguiculata (L.) Walp.], as shown by previous conflicting results describing the sensitivity of cowpea to drought. Two experiments, a three factor central composite, second order design in incomplete blocks, and a two factor split plot randomized block design, were used to quantify the yield responses of ‘California No. 5’ cowpea established at five row widths (25 to 125 cm), five plant densities (4 to 34 plants m−2), and five (0 to 200 cm) and two levels of irrigation at planting. Cowpea was grown on sandy clay loam soils (fine, mixed thermic families of Aridic and Torrertic Paleustolls) on the research farm in Lubbock and the Slab farm in Hereford, Tex. Seed yield was very dependent on irrigation, increasing linearly from 635 kg ha−1 to 2043 kg ha−1 at the Lubbock site without evidence of diminishing returns. At the second site more water was available from rainfall and irrigation and yields were greater (2837 kg ha−1). Highest yields were obtained with the combination of wide rows and high plant density while lowest yields resulted with high plant density in narrow rows. Of the components of seed yield, pod number per plant and seed number per pod were important regulators of seed yield, while seed size remained reasonably constant. Seed yield and harvest index results suggested that, in narrow rows, the more uniformly spaced plants explored the complete soil volume earlier, extracting more of the available soil water during vegetative growth, and leaving less available for reproductive growth than in wide rows. This restriction on reproductive development in narrow rows was accentuated most when plant densities were highest. Our study shows the need to examine plant interactions before management recommendations can be firmly established.