bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Diurnal Variation in Light and Temperature on the Acetylene Reduction Activity (Nitrogen Fixation) of Subterranean Clover1
Authors: Eckart Jeffrey F. , Raguse Charles A. 
Published: July 2010

AbstractSingly, or in combination, both light intensity or temperature can limit symbiotic N fixation. Most reported studies have been done to investigate the effects of only one of these factors. The present study was done to determine N fixation response to variation in both light and temperature for an annual range legume which, during its normal growing season, may be subject to growth limiting levels of both environmental factors. Plants of subterranean clover (Trifolium subterraneum L., ‘Mt. Barker’) were grown from seed to the sixth trifoliolate leaf stage in sand with N‐deficient nutrient solution. Plant containers were designed to permit sampling of the rooting atmosphere for acetylene reduction assay during treatment conditions, which were maintained with controlled‐environment facilities. During the treatment phase light and temperature were investigated by: 1) varying both diurnally; 2) varying light diurnally under constant temperature; 3) varying temperature diurnally under constant light; and 4) maintaining both light and temperature constant. Apparent N2 fixation (acetylene reduction) showed diurnal fluctuations under: 1) constant light; and 2) 12/12 hour light/dark regimes when root and air temperature fluctuated by 7 and 14 C, respectively. In constant temperature and either normal photoperiods or constant light, however, no significant diurnal fluctuation of acetylene reduction was measured. Under both constant temperature regimes a gradual increase in acetylene reduction activity, which may have been an artifact, was observed. These results show that diurnal changes in acetylene reduction by subterranean clover result more from fluctuations in temperature than from diurnal changes in light and suggest that N2 fixation by root nodules of this species is buffered against short‐term changes in photosynthate supply.
Effect of the Hydrogenase System in Rhizobium japonicum on the Nitrogen Fixation and Growth of Soybeans at Different Stages of Development1
Authors: Zablotowicz R. M. , Russell S. A. , Evans H. J. 
Published: July 2010

AbstractThe process of N fixation is energy consuming and inefficient. In most cases 20 to 40% of the energy that is supplied to nitrogenase for the reduction of N2 is utilized for the reduction of protons to H2. Some strains of R. japonicum contain a membrane‐bound hydrogenase that is capable of oxidizing all of the H2 that is produced during N2 fixation. This study was conducted to evaluate the effects of inoculation of soybeans [Glycine max (L.) Merr.] with Rhizobium japonicum containing H2 recycling capability on N fixation efficiency and soybean yield at various physiological stages of growth.In these experiments, a H2‐oxidizing strain SR (Hup+) and SR3 (Hup−), a mutant derived from SR which is unable to oxidize H2, were utilized. Soybeans cv. ‘Wilkin’ were grown under bacteriological conditions utilizing a drip‐irrigated nutriculture system. Nodules from plants inoculated with SR evolved no measurable amount of H2, while nodules from plants innoculated with SR3 evolved between 2.7 and 10 µmoles of H2/g nodules/ hour depending upon physiological age. Acetylene reduction rates by strain SR were significantly higher than those of nodules formed from SR3 during the vegetative, late pod‐fill, and leaf senescence stage of growth, respectively. Dry matter accumulation was significantly higher in plants inoculated with SR than in plants inoculated with SR3 (31% increase during vegetative stage, 25% during flowering, and 27% during pod‐fill stage). Nitrogen contents of shoots and seeds were significantly higher in plants inoculated with strain SR, demonstrating increased N fixation by nodules formed by Hup+Rhizobium. Our results support the conclusion that strains of R. japonicum selected for inoculation purposes should contain H2‐oxidizing capability as one of their desired characteristics.
Nitrate Uptake Effectiveness of Different Cultivars of Triticale, Wheat, and Rye1
Authors: Mugwira L. M. , Elgawhary S. M. , Allen A. E. 
Published: July 2010

abstractNitrate absorption and utilization vary among plant species and varieties but there is little information on the nitrate uptake effectiveness of triticale (X Triticose. cale, Wittmack), wheat (Triticum aestivum L.), and rye (Secale cereale L.). The nitrate uptake effectiveness of different cultivars of triticale, wheat, and rye were investigated in a growth chamber, using nutrient solutions. Plants were grown in pots containing the same base solution for 28 days before being transferred to solutions containing different nitrate concentrations. The solutions contained 0.1, 1.0, 2.5, 5.0, and 10.0 mM nitrate. Increasing nitrate concentration from 0.1 to 2.5 mM increased plant dry matter and N uptake. Few significant differences were observed at nitrate concentrations greater than 2.5 mM. Root uptake coefficients decreased with increasing nitrate concentration. Triticale '6TA 385', 'Arthur' wheat, and 'Abruzzi' rye showed higher effectiveness than triticale '6TA 203', 'Atlas 66' wheat, and 'Vitagraze' rye in the uptake of nitrate at 0.1 and 1.0 mM nitrate concentrations but these differences were not obtained at higher nitrate concentrations. Varietal differences within species indicated that triticale, wheat, and rye had similar nitrate uptake effectiveness.
Response of Winter Wheat to Inhibiting Nitrification of Fall‐Applied Nitrogen1
Authors: Huber D. M. , Warren H. L. , Nelson D. W. , Tsai C. Y. , Shaner G. E. 
Published: July 2010

AbstractLarge overwinter leaching and denitrification losses of fall‐applied N are common in many Corn Belt soils cropped to wheat (Triticum aeslivum L.). These losses decrease the utilization efficiency of N fertilizers, lower crop yields and quality, necessitate multiple fertilizer applications, and predispose wheat to several soil‐borne diseases. This study was conducted to determine if inhibiting nitrification of fall‐applied ammoniacal fertilizers would reduce N losses and be a practical alternative to multiple fertilizer applications in maintaining crop yield, quality, and tolerance to disease. We tested the effectiveness of a specific nitrification inhibitor, Z‐chloro‐6(trichloromethyl)‐pyridine (nitrapyrin), in reducing losses of fall‐applied NH4+ sources of N in four Indiana soils of varying texture. The field experiment was conducted over a 5‐year period by comparing the growth, disease incidence, grain protein, and yield of wheat in field plots receiving anhydrous ammonia, urea, or ammonium sulfate plus nitrapyrin with wheat production in plots treated with these N sources without the inhibitor. Calcium nitrate was used in some studies to provide a source of N exhibiting high potential for loss.Inorganic N analyses of soil showed that severe loss of N frequently occurring as a result of fall application of N may be markedly reduced by using a nitrification inhibitor. Wheat yields were increased as much as 40% (average increase was 14.7%) as a result of applying 0.55 kg of nitrapyrin/ha with fall‐applied NH4+ fertilizers. Yields obtained with fall‐applied N plus nitrapyrin were similar to those observed with a split‐application (25% fall—75% spring) of N without the inhibitor. Fall application at 44 kg N/ha plus nitrapyrin resulted in yield similar to those with 88 kg N/ha without the inhibitor. Inhibition of nitrification of fall‐applied NH4+ also increased protein content, minimized N loss from the up per soil profile, and reduced the severity of fungal root and crown rots. Nitrification inhibitors added to fall‐applied NH4+ should provide a practical alternative to multiple fertilizer applications for maintaining the yield, quality, and disease tolerance of wheat grown in the Corn Belt.
Field Drying of Rough Rice: Effect on Grain Yield, Milling Quality, and Energy Saved1
Authors: Calderwood D. L. , Bollich C. N. , Scott J. E. 
Published: July 2010

AbstractHarvesting rough rice (Oryza saliva L.) at a low moisture content is one method of reducing energy needs for drying. The objectives of energy‐related research were to: 1) determine the economic feasibility of harvesting rice at a low moisture content; 2) identify the harvest moisture level at which head rice yield drops sharply; 3) identify rice cultivars adaptable for field drying; and 4) estimate energy savings to be gained by harvesting at particular moisture levels.Rough rice initially at 25% moisture content was harvested at 11 intervals during a time span of 30 to 36 days to determine the amount of drying in the field and the effect of field drying on grain yield, milling yield, germination, and test weight. Ten tests were run during four harvest seasons. Long‐grain cultivars, ‘Labelle’ and ‘Lebonnet’, and medium‐grain cultivars, ‘Brazos’ and ‘Nato’, were included in the tests. During each of the tests, rice moisture content dropped steadily during dry weather, but rain and dew caused unpredictable amounts of rewetting. Rice eventually dried to near 16% moisture content in all 10 tests and to 14% moisture content or lower in five of the tests.Grain yields were not greatly affected by delayed harvesting, but tended to decrease before the tests were concluded. The percentage of total milled rice (whole and broken kernels combined) increased with delays in harvest date, but the percentage of head rice (whole kernels of milled rice) reached a maximum at an intermediate harvest date, then declined rapidly with delays in harvesting. Both Brazos and Lebonnet cultivars required harvesting at a higher moisture content than did Labelle and Nato cultivars to maintain a high percentage of head rice. Neither germination nor test weight was adversely affected by delays in harvest dates. Energy for drying may be reduced about 50% by harvesting rice at 16% rather than at 22% moisture content.
Adaptation of Cotton Genotypes to an Acid, Aluminum Toxic Soil1
Authors: Foy C. D. , Jones J. E. , Webb H. W. 
Published: July 2010

AbstractAluminum toxicity, associated with subsoil acidity, limits rooting depth of cotton (Gossypium hirsutum L.) in certain soils of the southern U.S. Shallow rooting means greater susceptibility to drought and less effective use of subsoil nutrients. Liming subsoil to detoxify Al is difficult and often not economically feasible. An alternative or supplemental approach is to select or breed cotton genotypes with greater Al tolerance.Fifty‐four cotton genotypes were screened for Al tolerance in greenhouse pots of an acid, Al‐toxic Tatum subsoil (clayey, mixed, thermic, typic Hapludult) treated with 375 µg/g CaCO3 (pH 4.7 to 4.9) or 3,000 µg/g CaCO3 (pH 5.3 to 5.4). Aluminum tolerance was measured by relative growth, which is defined as the dry weight of tops or roots at low pH (4.7 or 4.9) expressed as a percentage of that at the higher pH (5.3 to 5.4). In one experiment, relative yields of genotypes (pH 4.7 compared with 5.3) varied from 50 to 25% for tops and from 78 to 35% for roots. In a second experiment, relative yields (pH 4.9 compared with pH 5.4) ranged from 29 to 10% for tops, and from 51 to 12% for roots. Genotypes showing greatest tolerance to the acid subsoil included Pima S‐2, Acala 4‐42, LaDASS 5194, LaDASS 5187, Stoneville 213, Delcot 277, McNair 612, and Dixie King 3. Three Coker genotypes had tolerance approaching that of Stoneville 213; these were C‐Misc,73‐110, C‐Misc,73‐113 and C‐Sgs,71‐704. More sensitive genotypes were Auburn 56, Coker 201, Deltapine 16 and several experimental lines, including LaDSI 19979, C‐Misc,73‐114, C‐8103, 71‐106, and C‐7105‐73‐319.Acid soil tolerant and sensitive genotypes did not generally differ significantly in concentrations of Al, Mn, Ca, or P in whole plant tops. However, Al and Ca concentrations tended to be higher in chlorotic and/or cupped leaves than in normal leaves of selected genotypes.Results indicated that cotton genotypes vary significantly in Al tolerance and that further improvement may be made through plant selection and breeding. This approach has the potential to alleviate the shallow rooting problem of cotton in strongly acid subsoils. Very high correlation (0.001 level) between top and root yields (r = 0.968 and r = 0.979) in two experiments on the acid Tatum subsoil (pH 4.7 to 4.9) indicated that measurement of either component may be adequate in screening populations for Al tolerance.
Photoassimilate Distribution in Spartina alterniflora Loisel. II. Autumn and Winter Storage and Spring Regrowth1
Authors: Lytle R. W. , Hull R. J. 
Published: July 2010

AbstractVegetative regeneration of natural Spartina alterniflora Loisel. stands is critical to the stability and sustained productivity of Atlantic tidal salt marshes. Environmental conditions and human activity may limit the seasonal regeneration of energy reserves in perennial vegetative organs. Therefore, the use of energy stored in overwintering organs for vegetative growth in the spring was investigated. Leaf blades of mature flowering culms were exposed to 14CO2 during October. Entire plants were harvested during the ensuing winter and growing season. Distribution of 14C‐photosynthate in plants was measured by radioassay and radioautographic techniques. Approximately 50% of the late‐season photosynthate recovered from the plants had been translocated to basal organs, with rhizomes and tillers serving as major accumulation sites. During spring growth, almost half of the remaining stored 14C was translocated into tillers and plants emerging from rhizome buds. Shoots drew heavily upon stored energy sources through the fourth to fifth leaf stages of development. In mid‐summer, new rhizomes were regenerated largely by using energy stored in overwintered rhizomes. In S. alterniflora, energy transferred from one season to the next was utilized in suppport of early shoot growth and to produce organs which would serve as current season storage.
Annual Carbohydrate Variation in Culms and Rhizomes of Smooth Cordgrass (Spartina alterniflora Loisel.)1
Authors: Lytle R. W. , Hull R. J. 
Published: July 2010

AbstractThe productivity and stability of northeastern Atlantic tidal salt marshes depend largely upon the growth and persistence of the tall and short ecophenes of smooth cordgrass (Spartina alterniflora Loisel.). While the annual energy balance upon which perennial grass persistence depends has been studied in the tall form, no such information is available for the short form. The seasonal energy relations of the two morphological forms were compared based upon changes in the nonstructural carbohydrate content of rhizomes and culm tissues. Grass stands growing on a tidal marsh composed of sandy sulfaquents with occasional histic epipedons were sampled at 2‐week intervals during 3 years. Lipids, sample sugars, long chain fructosans, and starch were extracted in chloroform, ethanol, water, and perchloric acid, respectively. Carbohydrates were quantified by standard spectrophometric methods. Sucrose was the major carbohydrate extracted from culms and rhizomes throughout the year. Rhizomes never contained more than 4% starch while ethanol extractable sugars were 20% of dry weight in early spring and autumn. Almost no fructosans were detected in these tissues. During flowering and gram filling in August, the simple sugar content of tall culms was about 10% of dry weight but declined sharply between September and October which was coincident with carbohydrate accumulation in rhizomes. Short plants flowered less and continued Vegetative growth into autumn. Culm tissues of short plants retained a relatively high simple sugar content through October and rhizome carbohydrate levels increased gradually during autumn and early winter. It is proposed that the persistent vegetative growth of the short ecophene may result in less annual rhizome turnover than occurs in the tall form.
Osmoconditioning of Soybean Seeds to Improve Performance at Suboptimal Temperatures1
Authors: Knypl J. S. , Khan A. A. 
Published: July 2010

AbstractThe use of osmotic treatment or osmoconditioning (OC) to improve the performance of soybeans (Glycine (L.) Merrill cv. ‘Traverse’) was explored. The aim of this investigation was to examine in detail the optimum conditions needed for OC of soybean seeds for germination and soil emergence at suboptimal temperatures. Such a study is necessary if soybeans are to be planted early in the season when the soil is moist and cold. Osmotic treatment consisted of treating seeds with various concentrations of polyethylene glycol‐6000 (PEG) solutions at 15 C. Following osmotic treatment, seeds were germinated either on filter paper soaked with water or in a soil medium. The treatment improved the performance of soybean seeds as shown by axvancement in the time of germination and an increase in the rate of germination and emergence at suboptimal temperatures (8 or 15 C). The optimum time period of 06 at 15 C was in the range of 4 to 8 days, and the most favorable range of PEG concentration for OC was 25 to 30 g/100 ml of water (−8.6 to −11.9 bars). Following OC, drying the seeds to the original air dry weight did not remove the germination advantage gained by OC. Although 0.20/, thiram added to PEG solution improved the appearance of the seedling, it did not affect OC. These studies suggest that it might be possible to plant osmoconditioned seeds in moist, cold soil to extend the planting Season and/or to improve the uniformity of seedling stand.
Fungal Effects on Rhizobium japonicum‐Soybean Symbiosis1
Authors: Angle J. S. , Pugashetti B. K. , Wagner G. H. 
Published: July 2010

AbstractSoil fungi are known to produce mycotoxins which could inhibit growth and activity of other microorganisms in the soil. This study was undertaken to examine antagonistic effects of mycotoxins on growth of Rhizobium japonicum and on nodulation and growth of soybeans [Glycine max (L.)].Seventeen common fungi were isolated from the surface horizon of an Udollic ochraqualf and examined in laboratory and growth chamber studies to determine effects of these fungi on Rhizobium japonicum strains USDA 110 and 138. Several fungi were found to be antagonistic towards rhizobia due to mycotoxins which were exuded from the mycelia into the surrounding environment. During preliminary screening experiments Trichoderma viride, Rhizopus nigricans, and Mucor vesiculosis were observed to be consistently antagonistic to R. japonicum. Subsequently, these three fungi were inoculated simultaneously with rhizobia into perlite which was seeded to soybeans. The effect of each fungus on nodulation and growth of the soybeans during culture for 9 weeks was determined. The nodulation of soybeans by strains 110 and 138 was reduced by Trichoderma viride. Nodules per plant for strain 138 were reduced from a control value of 54 to 34. Total nodule weight and N2(C2H2) reduction also decreased, however, no changes were observed in plant shoot and root weight or in total N. Mucor vesiculosis increased nodulation and plant growth, while Rhizopus nigricans had no effect.In non‐sterile soil, Trichoderma viride was the only fungal isolate capable of reducing the R. japonicum population. The population was reduced to one tenth that of the control soil. Trichoderma viride also decreased nodule number which was accompanied by a decrease in N2(C2H2) reduction per soybean plant from a control value of 1.07 to 0.65 µmoles/hour. The antagonistic effects of Trichoderma viride on rhizobia1 activity were paralled by decreases in plant root and shoot weights. These plant parameters were similarly decreased, although not as severely, by Mucor vesiculosus and Rhizopus nigricans
Water Deficit Effects on Water Potential, Yield, and Water Use of Cowpeas1
Authors: Shouse Peter , Dasberg Samuel , Jury W. A. , Stolzy L. H. 
Published: July 2010

AbstractPrevious studies report conflicting results regarding the sensitivity of cowpeas to growth stage water deficits. Our 2‐year field study was designed to monitor the effects of water deficit imposed at three growth stages on the yield and water use of cowpeas (Vigna ungiculata (L.) Walp.). Six irrigation treatments were used to impose the water deficit including a well watered control treatment (WWW) and five deficit treatments (DWW, WDW, WWD, DWD, WDD). Cowpeas were grown on a sandy loam soil (coarse‐loamy, mixed thermic Haplic Durixeralf) on the experimental farm in Riverside, California.The pre‐dawn leaf water potential, as measured by the pressure bomb technique, was a better indicator of crop water stress than was the midday leaf water potential. The pre‐dawn leaf water potential at any growth stage progressively decreased with time following cessation of irrigation, but completely recovered after soil water storage was recharged by irrigation or rain.The most sensitive growth stages to drought were flowering and podfilling, with yield reduction from 35 to 69% depending on the timing and length of the drought treatment. A soil water deficit during the vegetative stage had the least effect on crop yield. This, coupled with decreased evaporation, resulted in a water‐use efficiency which was greater than that of the control treatment, which was adequately watered throughout the season. The water‐use efficiencies of the other stage deficit treatments were decreased below that of the control because of large decreases in crop yield.Seed yield of cowpeas was found to be linearly related to an integrated water stress indicator based on the predawn measurement of leaf water potential.We found that the relative dry matter yield was linearly related to crop transpiration as determined by the difference between a water balance measurement of ET and modeled evaporation (T = ET meas. ‐ Emodeled).
Freezing Cold‐tolerant Parental Clones of Sugarcane1
Authors: Tai P. Y. P. 
Published: July 2010

AbstractSugarcane (a complex hybrid of Saccharum spp.) deteriorates after freezing damage. Efforts have been made to introduce the cold tolerance of S. spontaneum L. into commercial types. Six cold‐tolerant clones of F1 (commercial cultivar ✕ S. spontaneum) and BC1 progenies were used to evaluate the deterioration of Sugarcane after artificial freezing and to compare the deterioration characteristics of their crusher juice quality with those of two commercial cultivars. The characteristics of juice quality studied were pH, titratable acidity, percent sucrose, percent purity, and kg of sugar per metric ton of cane. Stalks were exposed to −4.4 to −5.0 C for 6 hours. Samples were ground at Week 0 (immediately after harvest) and at 1, 2, and 3 weeks after freezing. The juice of fresh cane, Week 0, of the six cold‐tolerant clones had higher pH and titratable acidity and lower percent sucrose, percent jurity, and kg of sugar per metric ton of cane than did that of either commercial cultivar (‘CP 57‐526’ or ‘CP 63‐588’). Low positive correlations between titratable acidity measurements made at the start and end of various time periods after freezing of sugarcane stalk samples indicate that the deterioration hi titratable acidity between sampling dates was either independent or associated in a loose manner. Titratable acidity for all six cold‐tolerant clones increased relatively slowly during the first 2 weeks after freezing. Titratable acidity after freezing is more indicative of cold damage than is percent sucrose, and selecton of clones for cold tolerance might be made more rapidly if titratable acidity were used as the selection criterion.