bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimating Symbolic Nitrogen Fixation by Trifolium subterraneum L. during Regrowth1
Authors: Phillips Donald A. , Jones Milton B. , Center D. Michael , Vaughn Charles E. 
Published: July 2010

AbstractTwo complementary experiments were conducted to determine whether symbiotic N2 fixation could be estimated by applying 15N technologies to Trifolium subterraneum L. organs that would remain after various grazing treatments. Both experiments analyzed monocultures and 50:50 mixtures of T. subterraneum L. and Bromus mollis L. planted at 2000 seeds/m2 in 15N‐supplemented Laughlin loam, a member of the fine‐loamy, mixed, mesic family of Ultic Haploxerolls. In one study, lysimeters were monitored through two growing seasons, while plant shoots were clipped once or three times during each growing season. In the other study, plants were grown in unleached pods under glasshouse conditions with various clipping treatments. Symbiotic N2 fixation was estimated by the 15N‐dilution method and compared with the value determined from a total N‐difference method that included leached N changes in the case of lysimeters. Clipping treatments had similar effects on both estimates of N2 fixation in clover monocultures when shoot 15N concentrations at the final harvest were used for the 15N‐dilution calculations. Shoot 15N values also produced estimates similar to the N‐difTerence method in clover‐grass mixtures harvested only at the end of the season, but such 15N‐dilution calculations consistently underestimated N2 fixation relative to the N‐difference method for clover‐grass mixtures clipped more than once. Using root or crown 15N concentrations to estimate N2‐fixation produced lower values than the N‐difference method in all clipping regimes and species compositions. A major difficulty in using either the 15N‐dilution technique or the N‐difference method to estimate N2 fixation in pastoral systems is that a measure of total reduced N harvested in the legume is required. This requirement can be met in clipping trials but not in continuous grazing studies. Efforts to calculate N2‐derived N in forage from 15N concentration in shoots, crowns, or roots remaining after previous clippings and reduced N in herbage of unclipped plants, a realistic technique for grazing studies, were inaccurate relative to the N‐difference method in this study. Thus one must conclude that although 15N technologies can estimate N2 fixation with the same relative accuracy as the N‐difference method in unclipped plants, neither technique can be applied with certainty when undetermined amounts of forage are removed by animals.
Response of Dry Beans to Daily Deficit Sprinkler Irrigation1
Authors: Miller D. E. , Burke D. W. 
Published: July 2010

AbstractDry beans (Phaseolus vulgaris L.) are an important irrigated crop in the Pacific Northwest, but no information is available as to their water requirements under high‐frequency sprinkler irrigation. The present study was conducted to evaluate the response of dry beans to variable amounts of water applied daily by sprinkler, as affected by soil water‐holding capacity. Studies were conducted on a Warden loam (coarse‐silty, mixed, mesic Xerollic Camborthids) near Prosser, Wash., and on a Quincy sand to loamy sand (mixed, mesic Xeric Torripsamments) near Paterson, Wash. Beans were irrigated uniformly by solid‐set sprinklers until near the time of full canopy, when irrigation variables were initiated and continued until harvest. At harvest yields of vines, clean beans, and seed weight were determined. On the loam soil yields were not reduced when daily sprinkler irrigation was much less than estimated evapotranspiration (ET). It was concluded that no more than 10 to 15 cm of water need be applied from full cover until harvest. On the sandy soil, yields increased with water applied up to the equivalent of nearly 100% estimated ET. On the sandy soil, with limited water holding capacity, it is not possible to reduce irrigation to much below estimated ET without loss in yield.
Relationships Between Leaf Water Potential, Canopy Temperature, and Evapotranspiration in Irrigated and NonIrrigated Alfalfa
Authors: Sharatt B. S. , Reicosky D. C. , Idso S. B. , Baker D. G. 
Published: July 2010

AbstractA prerequisite to exploiting potential production of any crop is to accumulate a knowledge of plant responses, whether the response is to climate, fertilizer, or water. This paper describes a study on a Waukegan silt loam soil (fine‐silty over sandy or sandy skeletal, mixed, mesic Typic Hapludolls) where stress differences between irrigated and nonirrigated alfalfa (Medicago sativa L.) were evaluated during the daytime in order to expand the limited information available on alfalfa water relations. Canopy temperature (CT), evapotranspiration (ET), and leaf water potential (Χ1 served as indicators of stress and were measured using an infrared thermometer, portable chamber, and pressure chamber, respectively. Canopy temperature and ET did not differ appreciably between irrigated and nonirrigated alfalfa in early morning, but after 0900 h and throughout the afternoon nonirrigated alfalfa had a higher CT and lower ET. Leaf water potential of nonirrigated alfalfa was consistently lower during the day. The maximum difference in CT, ET, and Ψ1 between irrigated and nonirrigated alfalfa occurred at 1500 h where they equalled 2°C, 0.2 mm/h, and 0.7 MPa, respectively. These stress differences reflected the differences in the plant available water of 280 and 60 mm (corresponding to 117 and 25% of extractable water) in the 1.83‐m soil profile of the irrigated and nonirrigated plots, respectively. Nonirrigated alfalfa Ψ declined at a faster rate as the peak stress period (1500 h) was approached; however, after this period a faster rehydration was observed for this treatment, as indicated by the relationship between and ET. Despite the faster rehydration of nonirrigated alfalfa, the degree of hysteresis was greater for this treatment than for irrigated alfalfa. The relationship between CT and ET indicated a larger rate of change in CT prior to the peak stress period for nonirrigated as compared to irrigated alfalfa. After this time and until 1700 h, CT remained constant as ET decreased, indicating a decreasing ratio between ET and net radiation and thus greater restrictions on water movement through the plant, a direct cause of the hysteresis observed.
Effects of Wastewater Irrigation and Plant and Row Spacing on Soybean Yield and Development1
Authors: Cordonnier M. J. , Johnston T. J. 
Published: July 2010

AbstractConsiderable research has demonstrated that soybean [Glycine max (L.) Merr.] yields can be increased with the addition of supplemental water during reproductive stages, but little information is available concerning the use of municipal wastewater as the water source. Variables included in this field study were: three water regimes‐municipal wastewater, well water and no water; two row spacings‐51 and 76 cm; two in‐row spacings‐20 and 32 plants/m and two cultivars‐Nebsoy and Harcor. Soybeans planted on a Miami silt loam soil (fine‐loamy, mixed, mesic Typic Hapludalf) received a total of 9.8 cm of wastewater or well water as overhead spray irrigation in 1979 and 9.4 cm in 1980. Data were collected on seed yield, agronomic characteristics, dry matter production, leaf photosynthesis, and leaf chemical analysis. Seed yields were significantly different for water treatments in 1979 with 2,430, 2,580, and 2,790 kg ha−1 for no water, well water and wastewater, respectively. Yields generally increased as plant population increased with the greatest yield for both cultivars occurring at the highest plant population (645,500 plants ha−1). Irrigated plants were 4 to 5 cm taller, matured 5 to 6 days later, had larger seeds and lodge slightly more than nonirrigated plants. The two cultivars responded differently to the wastewater, with Harcor exhibiting a better response than Nebsoy. The 1980 growing season was wetter than normal and there was little or no yield response to irrigation. Under the conditions of soil type, climate and wastewater quality found during this experiment, wastewater was generally superior to well water in increasing yields.
The Effect of Root Temperature and NO−3/NH+4 Ratio on Strawberry Plants. I. Growth, Flowering, and Root Development1
Authors: Ganmore‐Neumann Ruth , Kafkafi U. 
Published: July 2010

AbstractThe purpose of this work was to study the effect of various NO−3/NH+4 ratios in the nutrient solution at various root temperatures on strawberry (Fragaria ananassa) plants. The results could lead to a suitable NO−3/NH+4 ratio of the fertilizer solution to be applied in field‐grown strawberry plants in different seasons on sandy soils.3 Strawberry plants were selected for uniformity and transferred individually to a 1 L container through which the nutrient solution was flushed at a rate of 1 L/h. The total N concentration was 7 me/L. Five ratios of NO−3/NH+4, 7/0, 5/2, 3.5/3.5, 2/5, and 0/7, respectively, were used, each at four root temperatures (10, 17, 25, and 32°C). Constant NO−3/NH+4 ratio, constant total nutrient concentration, and constant pH (6.2) were maintained for 8 weeks. There is a general decline in root growth with increasing root temperature when a single source of N is supplied. This decrease is followed with a decrease in the sugar concentration of the roots. At 32°C root temperature gradual increase in the NH+4 fraction in the nutrient solution is followed by gradual deterioration of the plants to a complete death at 100% NH+4. This death is related to the depletion of sugars and possible shortage of oxygen in the root cells due to NH+4 metabolism in the root.
Response of Several Genetic Sources of Corn to Acidic Soil1
Authors: Sherchan Kishor , Ellis Roscoe , Whitney David A. , Wassom Clyde E. 
Published: July 2010

AbstractPlants differ in their ability to take up nutrients. Developing genotypes efficient in utilizing nutrients from acid or low nutrient soils would aid in growing crops successfully when mineral supplementation is not feasible. This study was conducted in the greenhouse using mine spoil soil of initial pH 3.9 with variables of genetic sources of corn (Zea mays L.) and lime rates. Genetic source variability was more pronounced under stress conditions (low pH) than under nonstress conditions. The genetic sources PI270083, PI270080, and Va17 showed higher tolerance to acidic conditions than others. Inbred C105, highly susceptible to low pH, showed the most visual root damage as well as the lowest relative dry matter yield. Aluminum concentration in the plant tissue did not vary significantly with lime level; however, exchangeable Al in the soil decreased drastically as the level of lime application increased. Manganese in the plant tissue and in the soil (DTPA extractable) both decreased with increased lime rate. Dry matter yield decreased significantly at 16 500 kg ha−1 of lime compared with 8000 kg ha−1. Phosphorus concentration decreased in the plant as well as in the soil (Bray P‐1 extractable) at 16 500 kg ha−1 lime, which could have been a factor in reduced yield. Genetic source by lime interaction was significant for Ca, Mg, Al, and Mn concentration indicating that selection under different pH levels would be productive.
Foxtail Barley Heading, Yield, and Quality as Influenced by Growth Regulators and a Desiccant1
Authors: White Larry M. 
Published: July 2010

AbstractFoxtail barley (Hordeum jubatumL.) mixed with other forages harvested after heading or accumulated material bears awns that mechanically injure livestock and game animals upon consumption. This study examines the use of several growth regulators and a desiccant on supression of heading of foxtail barley and subsequent changes in forage yield and quality. During 1979 and 1981, stands of foxtail barley on two subirrigated, lowland sites (Ustic Torrifluvent and Typic Ustifluvent soils) were treated at different stages with growth regulators, at different rates, and with a desiccant. Effects of treatments were determined on number of heads, dry matter (DM) yield, estimated in vivo DM digestibility, and crude protein concentration of the foxtail barley forage. Treatments (kg ai. ha−1) were as follows: metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] at 2.8, 5.6, and 8.4; mefluidide [N‐(2,4‐dimethyl‐5‐[[(trifluoromethyl)‐sulfonyl]amino]phenyl)a cetamide] at 0.28,0.56, and 0.84; maleic hydrazide (MH) [1,2dihydro‐3,6‐pyridazinedione] alone at 4.5; MH at 3.36 with chlorflurenol [methyl‐2‐chloro‐9‐hydroxyfluorene‐9‐carboxylate] at 1.12; and paraquat [1,1'dimethyl‐4,4'‐bipyridinum dichloride] at 0.9 with 0.5% (v/v) X‐77 (spreader‐activator). Paraquat and MH plus chlorflurenol were the only chemicals that consistently reduced heading of foxtail barley (83 to 98%) both years. Maleic hydrazide plus chlorflurenol also consistently reduced heading when applied either 1 or 3 weeks after the first floral primordia developed. Reducing heading more than 90% reduced DM yield more than 50% the 1st year and 80% the 2nd year. Reducing heading more than 90% increased estimated in vivo DM digestibility and crude protein from 10 to 90 g kg−1units both years depending upon the chemical, and rate, and date of application. The 1st year's results indicated that metolachlor and mefluidide should be applied within a week of when the first floral primordia of foxtail barley develops for maximum control of heading but additional research should be done to confirm this. Moisture stress of foxtail barley during May of 1981 limited the effectiveness of the growth regulators in controlling heading the 2nd year.
Fertilizer Placement Effects on Growth, Yield, and Chemical Composition of Burley Tobacco1
Authors: Sims J. L. , Casey M. , Wells K. L. 
Published: July 2010

AbstractApplication of high rates of commercial fertilizers to burley tobacco (Nicotiana tabacumL.) soils through commonly used broadcast methods increases the osmotic pressure of the soil solution and soil acidity. Such changes in the soil may result in damage to plant roots, nutrient toxicities and deficiencies, delayed growth and maturity, and reduced yields. The current study was conducted to determine the influence of placing N and K fertilizers in bands of varying width between rows on selected chemical characteristics of soil (Maury silt loam, clayey, mixed mesic, Typic Paleudalf) and on growth, yield, and chemical composition of burley tobacco, cv. Ky‐14. Field experiments were conducted during 1979 to 1980 at two locations. Treatments consisted of 840 kg NH4NO3ha−1and 672 kg K2SO4ha−1applied either broadcast or in bands 80, 60, 40, and 20 cm wide centered between rows. Plant samples were taken at 45 days, and after maturity and curing for growth, yield, and chemical analysis. Surface soil pH depression in the row decreased as distance of the fertilized band from the row increased and pH in rows of the 20 cm band treatment remained about 0.3 to 0.5 pH units higher throughout the season than in broadcast treatments. The reverse was true for soil pH in the fertilized bands, with the 20 cm band treatment having lowest pH. Placement of the fertilizer in bands away from the row resulted in decreased electrical conductivity of the soil solution in the row, in decreased DTPA‐extractable Mn in the row, lower concentration of plant Mn and K, and fewer days to flower. In contrast, banding increased plant dry weight (21 to 40%) and plant Mg concentration at 45 days, cured leaf yields (9%), value per ha, and cured leaf alkaloid concentration.
Yield and Quality of Switchgrass Grown Without Soil Amendments1
Authors: Balasko J. A. , Burner D. M. , Thayne W. V. 
Published: July 2010

AbstractAlthough cool‐season forages usually produce ample forage in spring and fall, there is a lack of summer pasture in many middle latitude and northern states in the USA. Low productivity in summer is accentuated in areas with soil and topographical limitations. The purpose of this study was to evaluate the productivity and nutritive value of ‘Blackwell’ switchgrass (Panicum virgatumL.) grown without addition of fertilizer or lime on a site of marginal fertility and harvested according to 10 cutting schedules. Plots were established on a fine‐loamy, mixed, mesic Ultic Hapludalf mapped as Culleoka‐Westmoreland and harvested according to one‐cut, two‐cut, and three‐cut schedules for 3 years. A residual harvest was made in early summer of 1981 to measure effects of previous cutting schedules on yield. Annual yields from the one cut per year schedules and the two cuts per year schedules with second harvests after frost were similar (7.3 to 8.1 Mg ha−1) and larger than those from other two and three cuts per year schedules. In vitro dry matter disappearance of switchgrass harvested at boot ranged from 504 to 576 g kg−1and decreased from 612 g kg−1on 10 July to 365 g kg−1on 16 September. Crude protein ranged from 30 to 70 g kg−1for all first cut forage. Quality of regrowth forage harvested before frost was higher than that of first cut forage, but regrowth usually represented less than 20% of seasonal yield. Results suggest that switchgrass managed in an extensive manner can contribute significantly to the amount of forage available to grazing beef cows in summer. Supplementation with protein, P, and Mg may be required as the opportunity for selective grazing is reduced.
Fate of 15N‐Depleted Ammonium Nitrate Applied to No–Tillage and Conventional Tillage Corn1
Authors: Kitur B. K. , Smith M. S. , Blevins R. L. , Frye W. W. 
Published: July 2010

AbstractCrop recovery and soil immobilization of fertilizer N under two different tillage systems was observed in a 3‐year study. Corn (Zea maysL.) was fertilized with 84 or 168 kg N ha−1as 15N‐depleted NH4NO3. Nitrogen was surface applied as a solution on a Maury silt loam soil (fine , mixed, mesic Typic Paleudalfs). There was no mechanical disturbance of the soil in the no‐tillage treatment (NT); conventional tillage (CT) consisted of spring plowing and disking. Grain yields with NT tended to be lower than yields with CT at the low N rate but equal or greater at the high N rate. However, these differences were not statistically significant. In 1980 fertilizer recovery in grain was 21 vs. 38 kg N ha−1for NT and CT, respectively, at the low N rate. At the high N rate, N recovery by corn grown under NT and CT was not significantly different. Results were similar in 1981. After adding 15N‐depleted fertilizer to the same plots for 3 years, 71 to 75% of the fertilizer was accounted for in harvested grain, stover, or soil. Neither tillage nor N rate had a large effect on the fraction of fertilizer N missing and presumed lost by denitrification and leaching. Nitrogen fertilizer remaining in the NT soil was 42% of that applied at the low fertilizer rate and 39% of that applied at the high N rate. In the CT plots apparent immobilization was 28 and 37% for the low and the high N rate, respectively. Approximately one‐half of the N apparently immobilized was located in the surface 5 cm of the NT soil, but immobilized N was more uniformly distributed in the top 30 cm of the CT soil. Increased immobilization of N at the surface of the NT soil seems to be the most likely explanation for reduced crop recovery of fertilizer with NT at low N rates.
Basic Development Rate in Spring Wheat1
Authors: Flood R. G. , Halloran G. M. 
Published: July 2010

AbstractThere have been a number of reports indicating that, in the absence of vernalization and photoperiod influences, there is a factor(s) which acts to exert control over the rate of development in bread wheat (Triticum aestivumL. em. Thell.). In an attempt to characterize this phenomenon more fully, three sets of wheat genotypes were examined for their rate of development in the absence of vernalization and/or photoperiod influences. Seventeen spring wheats, prevernalized and grown with an 18‐h photoperiod in an outdoor pot experiment were found to differ in development rate, indicating that it may be of significance to adaptability and yield, at least in this type of wheat. In a set of near‐isogenic lines of ‘Triple Dirk’ (differing for the vernalization response genes vrn 1 and vrn 2) their development rates were similar, indicating that it is not a manifestation of the action of genes for vernalization response. Additionally, the absence of a close correlation between the level of vernalization response and basic development rate in the 17 spring wheats indicates physiological independence between the two processes. Using growth apex dissection the various phases of floral development were followed in two Australian spring wheat cvs., Pinnacle and Falcon, at four times of sowing in an outdoor situation and grown under an 18‐h photoperiod. The cv. Falcon was much faster than Pinnacle from sowing to floral initiation, terminal spikelet, and ear emergence at the four times of sowing. While the vegetative phase in Pinnacle was generally longer than in Falcon, the spikelet initiation and stem elongation phases did not show the same relative prolongation. ‘Chinese Spring’/‘Thatcher’ chromosome substitution lines 7B and SD, pre‐vernalized for weekly periods from 0 to 8 weeks and grown with an 18‐h photoperiod in an outdoor pot experiment were used to investigate the chromosomal control of development rate in wheat. Chromosome 7B of Thatcher substituted in Chinese Spring reduced its vernalization requirement and increased its rate of development. Chromosome 5D of Thatcher did not alter either vernalization response or rate of development of Chinese Spring. In view of these data and earlier reports, the term “basic development rate” is proposed to denote differences between wheats in the rate of development in the absence of vernalization and photoperiod influences. Recognition of the phenomenon of basic development rate prompts a re‐evaluation of the developmental basis of flowering in wheat and other temperate plants.
Modified Stability Analysis of Farmer Managed, On‐Farm Trials1
Authors: Hildebrand Peter E. 
Published: July 2010

AbstractThe Farming Systems Research and Extension (FSR/E) approach to technology generation and promotion is creating interest in onfarm research. Described is a form of research design and analysis that explicitly incorporates variation in farmer management as well as in soils and climate, to help agronomists evaluate responses to treatments and partition farmers into recommendation domains. Mean treatment yields at each location are used as an “environmental index.” Individual treatment results are regressed on environmental index. A graphic distribution of confidence intervals within partitioned groups helps in selecting superior treatments. Data from unreplicated trials on 14 farms in two villages in Malawi were analyzed. The design was a 2 ✕ 2 factorial with two maize (Zea maysL.) cultivars and two fertilizer treatments (0 and 30 kg N/ha). Results show that in poorer maize environments, local flint cultivars were superior to an improved semi‐flint composite, with or without fertilizer. The composite yielded more than local material with or without fertilizer in better environments. In all cases there was a marked and significant response to fertilizer.