bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Fungicides and Herbicides on Nodulation and N2 Fixation in Soybean Fields Lacking Indigenous Rhizobium japonicum1
Authors: Rennie R. J. , Dubetz S. 
Published: July 2010

AbstractGrowing soybeans [Glycine max(L.) Merr.] under irrigation requires the use of herbicides and seed‐applied fungicides to control weeds and root diseases. Soils in southern Alberta contain no indigenous Rhizobium japonicumand thus inoculation is essential to the establishment of a successful N2‐fixing symbiosis in soybeans. Unfortunately, these chemicals may be incompatible with survival of the inoculated rhizobia. Accordingly, an evaluation was made of the effects of three seed‐applied fungicides, captan {N‐[{(trichloromethyl) thio]‐4‐cyclohexene‐l,2‐dicarboximidef}, thiram [bis(dimethylthiocarbamoyl)disulfide], and carbathiin (5,6,‐dihydro‐ 2‐methyl‐l,4‐oxathiin‐3‐carboxanilide); four herbicides applied as preplant incorporated, chloramben (3‐amino‐2,5‐dichlorobenzoic acid), linuron [3‐(3,4‐dichIorophenyl)‐l‐methoxy‐l‐methylurea], metribuzin [4‐amino‐6‐tert‐butyl‐3‐{methylthio)‐as‐triazin‐5(4H)‐on], and trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine); and one post‐emergence herbicide, diclofop {2‐[4‐(2,4‐dichlorophenoxy) phenoxy]propanoic acid}, on shoot N, seed yield, nodulation, acetylene‐reducing activity (ARA), and 15N‐determined N2fixation of soybean line ‘King Grain X005’ inoculated with granular rhizobial inoculant. The soil was an irrigated Chin loam (Typic Haploboroll).None of the fungicides or herbicides affected seed yield. Thiram and captan applied at 1.0 g kg−1seed reduced shoot N yield at anthesis but a lower rate of thiram (0.54 g kg−1seed) increased N yield. None of the fungicides affected ARA. Metribuzin applied at recommended rates caused erratic germination. Linuron significantly reduced ARA whereas trifluralin stimulated it in 1 year but had no effect in the other year. This alteration in ARA was not reflected in N or seed yield. 15N isotope dilution at levels of 15N natural abundance showed the plant received approximately 50% of its N from N2fixation at anthesis, and in agreement with ARA, showed no effect of chemical when proper rates were applied. We conclude that these herbicides and seed‐applied fungicides have no effect on nodulation and N] fixation under these experimental conditions when granular inoculant is applied.
Cultivar and Management Effects on Stand Persistence of Birdsfoot Trefoil1
Authors: Beuselinck P. R. , Peters E. J. , McGraw R. L. 
Published: July 2010

AbstractInteractions between growth habit and management of birdsfoot trefoil (Lotus corniculatusL.) are reported by other researchers to affect stand persistence. Stand persistence dependent on the longevity of plants within the stand can be confused with the persistence of stand resulting from natural reseeding in this crop. A field test of 10 birdsfoot trefoil cultivars differing in growth habit was planted in May 1979 on Mexico silt loam (Fine, montmorillinitic, mesic Udollic Ocharqualf) near Columbia, Mo. Commencing April 1980, effects of four management treatments on stand persistence were studied to determine the degree of emphasis to be given to growth habit in a program of genetic improvement for trefoil persistence. Volunteer seedling establishment was controlled with simazine [2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine]. Significantly lower herbage yields in stockpiled and unharvested managements were attributed to foliar blight caused by Rhizoctonia solaniKeuhn. Stand persistence, based on plant counts, was observed to be independent of management since plants within stands behaved more like biennials than perennials regardless of management. Cultivar by management effects on stand persistence were not significant (P>0.05). An average stand reduction of 90% was observed from April 1980 to 1982. Greatest reductions in stand counts were observed each year between April and October. An average disease score of 2.4, where 0 indicated root and crown tissues visibly free of decay and 5 indicated extensive decay, was obtained from 939 surviving plants examined in April 1982. Poor stand persistence could be explained in part by the foliar, crown, and root diseases found at the study site. Lack of differences in stand persistence and tolerance to disease may reflect the close ancestry of the entries tested. Emphasis on growth habit in a genetic improvement program for persistence in the Southern Corn Belt appeared less important than an examination of genetic resources for lowered susceptibility to disease.
Effects of Solar Radiation Regimes on Growth and N2 Fixation of Soybean, Cowpea, and Bushbean1
Authors: Eriksen F. I. , Whitney A. S. 
Published: July 2010

AbstractLegumes are commonly grown in the tropics under reduced solar radiation due to dense cloud cover and shading from plantation or tall intercrops. This paper examines the growth and N2 fixation of several grain legumes common to the tropics on an Oxic Haplustoll in Hawaii. Plantings were made in April (warm season) and November (cool season) of soybean (Glycine max L. Merr.) ‘Kahala’; cowpea (Vigna unguiculata Walp.) ‘TVu 1190’ (April) and ‘TVu 4557’ (Nov.); and bushbean (Phaseolus vulgaris L.) ‘Burpee Tenderpod’. Polypropylene netting was used to obtain 27, 45, 70, and 100% of the incoming solar radiation through the entire crop cycle. Consistent shading effects were with the three legumes during both warm and cool seasons even though absolute yields were lower in the cool season due to daylength and temperature sensitivity in soybean and cowpea. Nitrogen fixation parameters generally followed dry matter (DM) and seed yields. Total nodule activity (TNA) was very low in all the legumes at 27% sun. With the exception of bushbean at 27% sun, shading caused an 34% average reduction in DM and grain yields, vs a 50% reduction in TNA, and a 76% reduction in nodule mass. Soybean TNA peaked 3 to 4 weeks after flowering, cowpea (cool season) TNA peaked at flowering, and bushbean TNA peaked slightly before or at flowering. There was a tendency for a delay (≈ 2 weeks) at 70, 45, and 27% sun in the final stages of TNA, for summer and cool‐season soybean and bushbean. These delays were not noted for cowpea or cool‐season bushbean. Of the three legumes, cowpea was the least shade tolerant. It produced more DM at full sun than either soybean or bushbean, but at 27% sun, DM yields were similar for all three crops. The response of soybean to shade was intermediate with no reduction in DM and grain yield at 70% sun. Bushbean was the least affected by shading; in fact, maximum yields were obtained at 70% sun. At full sun, their leaves were yellow and seed weight was low; this problem could be corrected by N fertilization.
Prediction of Animal Performance on Bermudagrass Pasture from Available Forage1
Authors: Guerrero J. N. , Conrad B. E. , Holt E. C. , Wu H. 
Published: July 2010

AbstractBermudagrass [Cynodon dactylon (L.) Pers.] is a major warmseason perennial grass grown on improved pastures in the South. Available forage and its digestibility vary widely in a normal grazing season on bermudagrass pasture. A method is needed to predict steer (Bos sp.) gains from the amount and digestibility of available forage. Five bermudagrass cultivars differing in digestibility were grazed at different grazing pressures to produce four levels of available forage. Forage was classified by concentration of in vitro digestible dry matter (IVDDM) as high (>600 g kg−1 IVDDM), medium (530 to 600 g kg−1 IVDDM), or low ( <530 g kg−1 IVDDM) digestibility. At each level of IVDDM, average daily gain (ADG) of steers was fitted to an asymptotic function of available forage. On high, medium, and low digestibility forages, approximate asymptotic ADG values were 0.94, 0.74, and 0.31 kg, and 68,83, and 89 g forage kg−1 body weight day−1, respectively, were needed to produce the asymptotic ADG values. For steers to maintain their weight on high, medium, and low digestibility forage, 14,18, and 43 g forage dry matter kg−1 body weight day−1, respectively, must be present. Because the quantities of available forage required for maximum steer gains or even for maintenance were far in excess of what the steers could physically consume, it appears that opportunity for selective grazing is necessary.
Reduced Seedbed Tillage Effects on Irrigated Sugarbeet Yield and Quality1
Authors: Halvorson A. D. , Hartman G. P. 
Published: July 2010

AbstractField studies were conducted from 1979 through 1982 on a furrow irrigated silty clay loam soil (Typic Argiboroll) to determine if sugarbeet (Beta vulgaris L.) sucrose production levels could be maintained with reduced seedbed tillage. Tillage treatments were: a) conventional tillage (CT)—complete fall incorporation of surface residues; b) strip tillage (ST)—fall incorporation of surface residues in 18‐cm wide bands located 56 or 61 cm apart; and c) no‐tillage (NT)—no incorporation of surface residues. Herbicides were fall applied for weed control. Sugarbeets were seeded 10 or 15 cm apart to eliminate need for thinning. Sugarbeet stands before cultivation averaged 3.7 sugarbeets/meter of row over the 4‐year period. Tillage treatment had no significant effect on spring soil temperatures and on sugarbeet stand, root yield, sucrose content, gross sucrose yield, and recoverable sucrose yield when averaged over the 4‐year period. Sugarbeet quality, in terms of clear juice purity, tended to be better in the reduced tillage treatments than in the CT treatment. This difference in clear juice purity probably resulted from the higher levels of spring soil NO3‐N found under CT than under reduced tillage plots. The results indicate that sucrose production under reduced seedbed tillage conditions can be maintained at levels comparable with conventional seedbed tillage conditions. Potential advantages of reduced seedbed tillage for sugarbeets are wind erosion control, reduced soil crusting problems, better soil water conditions in the seedbed for germination, reduced energy requirements, and reduced production costs.
An Analysis of Post‐Anthesis Sink‐Limited Winter Wheat Grain Yields Under Various Environments1
Authors: Shanahan J. F. , Smith D. H. , Welsh J. R. 
Published: July 2010

AbstractBetter understanding of the frequency of post‐anthesis sink‐limited winter wheat (Triticum aestivum L.) grain yields is needed in selecting genotypes with high yield potential and yield stability. Field studies were conducted at four locations (the major soil types were mesic, Aridic Paleustolls and mesic, Aridic Argriustolls) in eastern Colorado over the two cropping seasons of 1976–1977 (1977) and 1977–1978 (1978), using yield and yield component analysis, to determine the effect of sink limitations. Three hard red winter wheat cultivars were grown under four N fertilizer rates at each location to increase variation in grain yield and yield components. Variation was observed for grain yield and the yield components of spike no. (spike no. m−2), kernel no. per spike, kernel no. (kernel no. m−2), and kernel size (mg kernel−1) across locations. Grain yield and yield component variation, due to cultivars or N treatments, were observed at six of the eight sites. Variation in grain yield within and across sites was more consistently correlated with kernel no. than kernel size. These results strongly suggest that wheat grain yields may be sink‐limited during grain filling over a wide array of environments. Variation in kernel no. within locations was more consistently correlated with kernel no. per spike than spike number, while variation in kernel no. across locations was more highly associated with spike no. than kernel no. per spike. Thus, both yield components were important in establishing sink capacity under the variable environmental conditions of this study.
Soybean Canopy Growth, Photosynthesis, and Transpiration Responses to Whole‐Season Carbon Dioxide Enrichment1
Authors: Jones Pierce , Allen L. H. , Jones J. W. , Boote K. J. , Campbell W. J. 
Published: July 2010

AbstractSoybeans [Glycine max (L.) Merr. cv. Bragg] were grown throughout their life cycle in six controlled‐environment chambers that maintained CO2 concentrations at 330,450,600, and 800 µmol CO2 mol−1 air. Air temperatures were controlled, and solar radiation and dewpoint temperatures were measured continually for each chamber. Net photosynthesis and transpiration were computed on 5‐min intervals. The CO2 enrichment had no apparent effect on the rate of mainstem node development, but leaf area increased at a faster rate proportional to the CO2 concentration. Daytime CO2 exchange rate (CER) increased with increasing CO2 and followed the same trend as final yield. Midday CER was typically about 90 µmol CO2 m−1 of ground area s−1 for 800 µmol mol−1 and 60 µmol CO2 m−2 ground area per second for 330 µmol mol−1 chambers. Canopy transpiration rates, leaf area index and vapor pressure deficits were used to compare bulk canopy resistances among CO2 treatments. Bulk canopy resistance (stomatal and boundary‐layer) of the 800 µmol mol−1 treatment was about 1.6 times that of the 330 µmol mol−1 CO2 treatment. These results imply that the expected continued increase in global atmospheric CO2 will increase both agricultural productivity and water use efficiency.
Effects of Municipal Wastewater Effluent and Cutting Management on Root Growth of Perennial Forage Grasses1
Authors: Clapp C. E. , Newman T. C. , Marten G. C. , Larson W. E. 
Published: July 2010

AbstractMunicipal wastewater effluent studies have not evaluated perennial forage root growth at different effluent rates or cutting sequences. Our primary objective was to ascertain whether root length and mass of perennial grasses, that are tolerant of wastewater effluent, but that yield differently depending on frequency of cutting, are influenced by effluent application or cutting frequency. The two, three, or four‐time year−1 cutting sequence had little effect on root length or dry weight, whereas wastewater treatment levels caused significant root differences. The high effluent (10 cm week−1) treatment produced less root length and root mass in all four species compared with the control and low effluent (5 cm week−1) treatments. When high levels of effluent were applied, reed canarygrass (Phalaris arundinacea L.) had the greatest root length and mass, whereas orchardgrass (Dactylis glomerata L.) had the least; tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.) had intermediate root production. Although orchardgrass produced significantly fewer roots than did reed canarygrass, previous work had shown the aboveground yields of these species were comparable. Also, the high effluent treatment produced the greatest yield of aboveground dry matter, the finest roots, the least root dry matter, and lowest rooting density. We concluded that root mass or length were not primary determinants of forage production of adapted perennial grasses when ample water and nutrients were provided by wastewater effluent.
Leaf Area Index and Dry Biomass of Taro1
Authors: Shih S. F. , Snyder G. H. 
Published: July 2010

AbstractTaro (Colocasia esculenta) is a wetland plant that can be used as a fuel stock for biomass conversion into various energy forms. Predicting the biomass production is important in developing the optimal harvesting schedule, but information needed to predict production is unavailable. The objective of this study was to predict the tare biomass production based on leaf area index information. Cultivar Lehua Maoli was planted with a space of 0.5 m between plants in 1981. In 1982, the same cultivar was planted with spaces of 0.2, 0.4, and 0.6 m between plants. Dry biomass and leaf area (LA) were monitored monthly in 1981 and bimonthly in 1982. Leaf area was best estimated from leaf dry biomass (LDB) by the equation LA = 223 LDB (r2=0.91). Dry biomass was linearly related to cumulative monthly mean leaf area index until cumulative monthly mean leaf area index reached 10 (r2=0.80 to 0.97). These relationships could be useful for predicting taro biomass production, both as a research tool and as a guide for scheduling commercial harvest.
Moisture Sensor‐Controlled Irrigation for Reducing N Leaching in Bermudagrass Turf1
Authors: Snyder G. H. , Augustin B. J. , Davidson J. M. 
Published: July 2010

AbstractThe study was conducted to determine the feasibility of using a tensiometer‐controlled irrigation system to reduce N leaching in turfgrass while maintaining acceptable growth. Bermudagrass (Cynodon dactylon × C. transvaalensis) was grown on a sand soil (Pomano fine sand, a siliceous, hyperthermic Typic Psammaquent) during a series of 2‐month (bimonthly) cycles. Irrigation was applied either daily (Daily irrigation), or when permitted by tensiometer soil moisture sensors (Sensor irrigation). Nitrogen at the rate of 5 g m−2 month−1 was applied bimonthly as NH4NO3, (AN) or sulfur‐coated urea (SCU), or as NH4NO3, through the irrigation system with each irrigation (Fertigation). The effect of these treatments on turfgrass color, clipping weights, and on tissue N content were measured. Nitrogen was determined in soil water samples obtained on a near daily basis from below the rootzone using ceramic cup suction lysimeters. Nitrogen leaching ranged from 56% to less than 1% of that applied, depending on treatment and cycle. The AN source combined with Daily irrigation produced the greatest N losses (22 to 56%), and Fertigation with Sensor irrigation produced the smallest losses ( <l to 6). Sensor irrigation reduced N leaching from all N sources. For SCU and Fertigation with Sensor irrigation, the peak and average N concentrations were less than 0.9 and 0.3 mmol L−1, respectively, whereas for AN these values were as high as 2.8 and 1.0, respectively. The combination of Sensor irrigation and fertilization by Fertigation or SCU produced the least N leaching while maintaining acceptable turfgrass growth and quality.
Yield Components Associated with Soybean Yield Reductions at Nonoptimal Planting Dates1
Authors: Board J. E. 
Published: July 2010

AbstractExpansion of the optimal planting dates for soybean [Glycine max (L.) Merr.) would allow for more flexibility in management to fit into weather and cropping patterns. A field study was conducted to determine yield components associated with soybean seed yield reductions at nonoptimal planting dates in the southeastern USA. This information provides insight into how seed yield reductions occur at nonoptimal planting dates. Optimal planting period in the area is between early May and early June. Cultivars Forrest, Tracy‐M, Centennial, Davis, Ransom, Bragg, and experimental genotype D77‐12480 were planted at early April (nonoptimal), mid‐May (optimal), and mid‐June (nonoptimal) planting dates in 1981 and 1982 at Baton Rouge, LA (30° N Lat) on an Olivier silt loam (fine‐silty, mixed, thermic Aquic Fragiudalf) soil. At maturity, plant samples were separated into main and branch stem components. Main and branch stem length, branch number, node number, fertile node number, pod number, pods per fertile node, seed per pod, seed size, and seed yield were determined. In all genotypes, seed yield reduction at the mid‐June planting date was related to a decline in branch seed yield associated with a reduction in number of branches and branch nodes. The decreased number of fertile branch nodes resulted in fewer branch pods and seed. Davis and D77‐12480 showed no seed yield reduction at the early April planting date. Reduced seed yield of the other genotypes at the early April planting date was related to a reduction in branch nodes and proportion of the branch nodes that were fertile. The decreased number of fertile branch nodes resulted in fewer branch pods and seed. In conclusion, seed yield reduction at nonoptimal planting dates was associated with reductions in branch rather than main stem yield components.
Mycorrhizal Colonization of Crested Wheatgrass as Influenced by Grazing1
Authors: Bethlenfalvay G. J. , Evans R. A. , Lesperance A. L. 
Published: July 2010

AbstractVesicular‐arbuscular mycorrhizal (VAM) fungi play a role in crop productivity and soil stability in agricultural ecosystems. This role is accentuated under adverse cultural or climatic conditions, such as grazing or drought. The purpose of this study was therefore to assess the effects of stress (grazing) on VAM‐fungal colonization of a major forage species. Changes in root colonization of crested wheatgrass [Agropyron desertorum (Frisch.) Schult.] plants by VAM fungi were measured under three levels of grazing pressure, ranging from no grazing to heavy, continuous grazing. Percent colonization of root length was determined by microscopy, and VAM‐fungal biomass spectroscopically. These findings were related to the changes in root/shoot ratios caused by grazing. The study site is characterized as a Wyoming big sage brush (Artemisia tridentata spp. Wyomingensis) ‐ grassland community on an Abgese loam (fine‐loamy, mixed, mesic Xerollic Haplargid) soil in central Nevada. Plants studied were introduced previously as part of a range improvement program. Colonization of root length declined significantly (P < 0.05) and seasonally (40.2%, June and 50.6%, October) in plants under heavy grazing as compared to ungrazed plants. Spores (60.8% June and 89.5% October) and biomass (35.0% June and 61.5, October) of the VAM fungi also declined with grazing. Colonization of wheatgrass was favored when the amount of photosynthetic tissue relative to root mass was high. Phosphorus concentration in plant tissues was not significantly affected (P < 0.05) by grazing. It is concluded that severe grazing adversely affects the colonization of crested wheatgrass by VAM fungi. This reduction in the fungal symbiont may have an effect on plant nutrition and soil structure and stability which needs further investigation.
Cicer Milkvetch and Alfalfa as Influenced by Two Cutting Schedules1
Authors: Gabrielsen B. C. , Smith D. H. , Townsend C. E. 
Published: July 2010

AbstractCicer milkvetch (Astragalus cicer L.) is a promising forage legume, but little is known about its response to cutting. A 2‐year study was conducted at Fort Collins, CO, on a Nunn clay loam (fine, montmorillonitic, mesic Aridic Argiustoll) soil to compare yield, quality, and trends in carbohydrate reserves of cicer milkvetch and alfalfa (Medicago sativa L.) in response to annual three‐ and four‐cut clipping treatments. Quality was evaluated by determining concentrations of crude protein (CP) and cell wall constituents (CWC) in herbage from each harvest. Seasonal dry matter yields of alfalfa were similar under both clipping treatments during each year. Yields of cicer milkvetch were reduced under the more frequent cutting schedule in 1979, but not in 1980. During 1979, quality differences between the clipping treatments were apparent for alfalfa but not for cicer milkvetch. Improved quality, as measured by increased CP and decreased CWC concentrations, was observed in herbage from both species under the more frequent clipping treatment in 1980. Herbage CP concentration was simiilar under comparable clipping treatments during both years, however, the CWC concentration of cicer milkvetch was consistently lower than that of alfalfa. Cyclic trends in carbohydrate reserves were observed in alfalfa under both clipping treatments in 1980, but only under the three‐cut treatment in 1979. Carbohydrate reserve trends in cicer milkvetch roots and rhizomes were less cyclic than in alfalfa and similar under both cutting schedules each year. Carbohydrate reserve concentrations in all forage entries were similar at the end of the 1980 growing season regardless of clipping treatment. Following cutting, carbohydrate reserves in alfalfa were readily utilized during the initial period of recovery. Carbohydrate reserves in cicer milkvetch appeared to be actively involved in regrowth processes only when little, or no, residual leaf area remained after cutting.