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Articles 31 - 60 of 79
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No Evidence That Bacillus Thuringiensis Genes And Their Products Influence The Susceptibility Of Corn Residue To Decomposition, R. Michael Lehman, Shannon L. Osborne, Kurt A. Rosentrater
No Evidence That Bacillus Thuringiensis Genes And Their Products Influence The Susceptibility Of Corn Residue To Decomposition, R. Michael Lehman, Shannon L. Osborne, Kurt A. Rosentrater
Kurt A. Rosentrater
The possibility that Bacillus thuringiensis (Bt) corn (Zea mays L.) residues resist decomposition compared to non-Bt residues would present direct (soil carbon turnover times) and indirect (changes in tillage practices) effects on carbon budgets in agricultural systems. We evaluated the relative decomposition of residue from two pairs of Bt and non-Bt corn hybrids from different seed manufacturers buried in the root zone of adjacent Bt and non-Bt corn plots over a period of 384 d. We found no persistent differences in residue decomposition among the different hybrids regardless of the seed manufacturer or the presence of the Bt genes (both …
Long-Term Tillage Frequency Effects On Dryland Soil Physical And Hydraulic Properties, Andrew W. Lenssen, J. D. Jabro, U. M. Sainju, W. B. Stevens, R. G. Evans
Long-Term Tillage Frequency Effects On Dryland Soil Physical And Hydraulic Properties, Andrew W. Lenssen, J. D. Jabro, U. M. Sainju, W. B. Stevens, R. G. Evans
Andrew W. Lenssen
Soil tillage is considered one of most important practices in agricultural production due to its influence on physical, chemical, and biological properties of the soil environment. The effect of a long-term tillage [no-till (NT), spring till (ST), and fall and spring till (FST)] was investigated on soil penetration resistance (PR), bulk density (BD), gravimetric water content (GWC) and saturated hydraulic conductivity (Ks) under dryland conditions. Tillage effects on these physical properties were tested after 22 years on a Dooley sandy loam (fine-loamy, mixed Typic Argiborolls) derived from glacial till parent material. The statistical design used was a randomized complete block …
Evaluation Of Winter Cereals For Pasture In Montana, Andrew W. Lenssen, A. N. Hafla, S. D. Cash, L. M. M. Surber, J. A. Paterson, A. L. Todd, M. S. Huffman
Evaluation Of Winter Cereals For Pasture In Montana, Andrew W. Lenssen, A. N. Hafla, S. D. Cash, L. M. M. Surber, J. A. Paterson, A. L. Todd, M. S. Huffman
Andrew W. Lenssen
In the southern Great Plains, it is common to graze winter wheat pastures prior to grain harvest to take advantage of economic returns from the grain crop and value added to livestock. In Montana, a similar management practice could provide complementary pasture for livestock in the late spring to relieve pressure on cool season native rangelands. A two year study was conducted to evaluate the forage yield and quality of winter cereals, when grazed at three growth stages, vegetative (V), boot stage (B), and at heading (H), prior to hay and grain harvest. Western white faced ewes were used to …
No Differences In Decomposition Rates Observed Between Bacillus Thuringiensis And Non-Bacillus Thuringiensis Corn Residue Incubated In The Field, R. Michael Lehman, Shannon L. Osborne, Kurt A. Rosentrater
No Differences In Decomposition Rates Observed Between Bacillus Thuringiensis And Non-Bacillus Thuringiensis Corn Residue Incubated In The Field, R. Michael Lehman, Shannon L. Osborne, Kurt A. Rosentrater
Kurt A. Rosentrater
Recent speculation of slower residue decomposition for Bacillus thuringiensis (Bt) corn (Zea mays L.) hybrids compared with non-Bt corn hybrids has prompted investigative study. We evaluated the residue decomposition rates of Bt and non-Bt corn hybrids over a period of 22 mo under field conditions using the litter bag technique. The four corn hybrids used were (i) DKC60–16 (Bt+, Cry1Ab protein active against the leptidopteran European corn borer, event MON810), (ii) DKC60–12 (Bt+, Cry3Bb1 protein active against the coleopteran corn rootworm, event MON863), (iii) DKC60–14 (stacked Bt++, Cry1Ab and Cry3Bb1 proteins) and, (iv) DKC60–15 (Bt−, base genetics). The biochemical and …
Long-Term Tillage And Cropping Sequence Effects On Dryland Residue And Soil Carbon Fractions, Upendra M. Sainju, Thecan Caesar-Tonthat, Andrew W. Lenssen, Robert G. Evans, Robert Kolberg
Long-Term Tillage And Cropping Sequence Effects On Dryland Residue And Soil Carbon Fractions, Upendra M. Sainju, Thecan Caesar-Tonthat, Andrew W. Lenssen, Robert G. Evans, Robert Kolberg
Andrew W. Lenssen
Long-term management practices are needed to increase dryland C storage and improve soil quality. We evaluated the 21-yr effects of combinations of tillage and cropping sequences on dryland crop biomass (stems + leaves) returned to the soil, residue C, and soil C fractions at the 0- to 20-cm depth in a Dooley sandy loam (fine-loamy, mixed, frigid, Typic Argiborolls) in eastern Montana. Treatments were no-till continuous spring wheat (Triticum aestivum L.) (NTCW), spring-tilled continuous spring wheat (STCW), fall- and spring-tilled continuous spring wheat (FSTCW), fall- and spring-tilled spring wheat–barley (Hordeum vulgare L.) (1984–1999) followed by spring wheat–pea (Pisum sativum L.) …
Diversified Cropping Systems In Semiarid Montana: Nitrogen Use During Drought, Andrew W. Lenssen, J. T. Waddell, G. D. Johnson, G. R. Carlson
Diversified Cropping Systems In Semiarid Montana: Nitrogen Use During Drought, Andrew W. Lenssen, J. T. Waddell, G. D. Johnson, G. R. Carlson
Andrew W. Lenssen
Improved nitrogen use efficiency would be beneficial to agroecosystem sustainability in the northern Great Plains of the USA. The most common rotation in the northern Great Plains is fallow–spring wheat. Tillage during fallow periods controls weeds, which otherwise would use substantial amounts of water and available nitrogen, decreasing the efficiency of fallow. Chemical fallow and zero tillage systems improve soil water conservation, and may improve nitrogen availability to subsequent crops. We conducted a field trial from 1998 through 2003 comparing nitrogen uptake and nitrogen use efficiency of crops in nine rotations under two tillage systems, conventional and no-till. All rotations …
The Strength Of Seeds And Their Destruction By Granivorous Insects, Jonathan G. Lundgren, Kurt A. Rosentrater
The Strength Of Seeds And Their Destruction By Granivorous Insects, Jonathan G. Lundgren, Kurt A. Rosentrater
Kurt A. Rosentrater
The influence of seed structure and strength on their destruction by granivores is central to understanding the dynamics of granivore-plant interactions. For up to nine seed species, the effects of seed size (cm3), mass (mg), density (mg/cm3) and coat strength (MPa) on the damage inflicted by three post-dispersal granivores (Harpalus pensylvanicus, Anisodactylus sanctaecrucis, and Gryllus pennsylvanicus) were evaluated. Seed destruction rates by G. pennsylvanicus were statistically unrelated to the size and toughness of the seeds. Seed densities significantly affected their destruction by A. sanctaecrucis and H. pensylvanicus, as did seed size, mass, and strength in H. pensylvanicus under choice conditions. …
Dryland Plant Biomass And Soil Carbon And Nitrogen Fractions On Transient Land As Influenced By Tillage And Crop Rotation, Andrew W. Lenssen, Upendra M. Sainju, Thecan Caesar-Thonthat, Jed Waddell
Dryland Plant Biomass And Soil Carbon And Nitrogen Fractions On Transient Land As Influenced By Tillage And Crop Rotation, Andrew W. Lenssen, Upendra M. Sainju, Thecan Caesar-Thonthat, Jed Waddell
Andrew W. Lenssen
Soil and crop management practices may alter the quantity, quality, and placement of plant residues that influence soil C and N fractions. We examined the effects of two tillage practices [conventional till (CT) and no-till (NT)] and five crop rotations [continuous spring wheat (Triticum aestivum L.) (CW), spring wheat–fallow (W–F), spring wheat–lentil (Lens culinaris Medic.) (W–L), spring wheat–spring wheat–fallow (W–W–F), and spring wheat–pea (Pisum sativum L.)–fallow (W–P–F)] on transient land previously under 10 years of Conservation Reserve Program (CRP) planting on the amount of plant biomass (stems + leaves) returned to the soil from 1998 to 2003 and soil C …
Incorporating Sheep Into Dryland Grain Production Systems Iii. Impact On Changes In Soil Bulk Density And Soil Nutrient Profiles, P. G. Hatfield, H. B. Goosey, T. M. Spezzano, Sue L. Blodgett, Andrew W. Lenssen, R. W. Kott, C. B. Marlow
Incorporating Sheep Into Dryland Grain Production Systems Iii. Impact On Changes In Soil Bulk Density And Soil Nutrient Profiles, P. G. Hatfield, H. B. Goosey, T. M. Spezzano, Sue L. Blodgett, Andrew W. Lenssen, R. W. Kott, C. B. Marlow
Andrew W. Lenssen
Changes in soil bulk density and soil nutrient profiles are a major concern of dryland grain producers considering grazing sheep on cereal stubble fields. Our objective was to compare burned, grazed, tilled, trampled and clipped wheat stubble fields on changes in soil bulk density and soil nutrient profiles. Treatments were evaluated in a series of three experiments using a randomized complete block design and four replications at each site. Contrast statements were used to make pre-planned comparisons among treatments. For Experiment 1, treatments were fall tilled, fall grazed, spring grazed, fall and spring combined (Fall/Spr) grazed, and an untreated control. …
Incorporating Sheep Into Dryland Grain Production Systems Ii. Impact On Changes In Biomass And Weed Density, P. G. Hatfield, Andrew W. Lenssen, T. M. Spezzano, Sue L. Blodgett, H. B. Goosey, R. W. Kott, C. B. Marlow
Incorporating Sheep Into Dryland Grain Production Systems Ii. Impact On Changes In Biomass And Weed Density, P. G. Hatfield, Andrew W. Lenssen, T. M. Spezzano, Sue L. Blodgett, H. B. Goosey, R. W. Kott, C. B. Marlow
Andrew W. Lenssen
Weed control in fallow management to conserve soil moisture and nutrients is the largest variable cost to dryland grain production. Our objective was to compare burning, grazing, tilling, trampling and clipping wheat stubble fields on changes in total above ground biomass and weed density. Treatments were evaluated in three experiments using a randomized complete block design for each experiment with four replications at each site. Contrasts statements were used to make pre-planned comparisons. For experiment 1, treatments were fall tilled, fall grazed, spring grazed, fall and spring combined (Fall/Spr) grazed, and an untreated control. For grazing treatments, five mature ewes …
Comparative Structural Study Of Leaf Spot Disease Of Safflower And Sugar Beet By Cercospora Beticola, Robert T. Lartey, Andrew W. Lenssen, Robert G. Evans, Soumitra Ghoshroy
Comparative Structural Study Of Leaf Spot Disease Of Safflower And Sugar Beet By Cercospora Beticola, Robert T. Lartey, Andrew W. Lenssen, Robert G. Evans, Soumitra Ghoshroy
Andrew W. Lenssen
Sugar beet and safflower are sometimes rotated or grown side by side in the Sidney, MT region of the Lower Yellowstone River Basin (LYRB). Cercospora beticola and C. carthami infect sugar beet (Beta vulgaris) and safflower (Carthamus tinctorius) respectively. C. beticola is ubiquitous in sugar beet, but C. carthami has not been reported in LYRB. Observations of unusual leaf spots on safflower in Sidney led to investigation and subsequent identification of safflower as a host of C. beticola. We describe a comparative structural study of progression of C. beticola infection and disease development in both sugar beet and safflower. The …
Incorporating Sheep Into Dryland Grain Production Systems I. Impact On Over-Wintering Larva Populations Of Wheat Stem Sawfly, Cephus Cinctus Norton (Hymenoptera: Cephidae), P. G. Hatfield, Sue L. Blodgett, T. M. Spezzano, H. B. Goosey, Andrew W. Lenssen, R. W. Kott, C. B. Marlow
Incorporating Sheep Into Dryland Grain Production Systems I. Impact On Over-Wintering Larva Populations Of Wheat Stem Sawfly, Cephus Cinctus Norton (Hymenoptera: Cephidae), P. G. Hatfield, Sue L. Blodgett, T. M. Spezzano, H. B. Goosey, Andrew W. Lenssen, R. W. Kott, C. B. Marlow
Andrew W. Lenssen
Wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae) is the most damaging insect pest to Montana’s $1 billion dollar per year grain industry. Current WSS control methods are either expensive, reduce wheat yields, or are not effective. Our objective was to compare burning, grazing, tilling, trampling and clipping wheat stubble fields on over-wintering WSS larval populations. Treatments were evaluated in three experiments using a randomized complete block design and four replications at each site. Eight, six, and two sites were used for Experiments 1, 2, and 3, respectively. Contrast statements were used to make pre-planned comparisons among treatments. For …
Farming Systems Research On Crop Diversification, Tillage, And Management Effects On Yield, Pests, And Environmental Quality In A Semi-Arid Environment, Andrew W. Lenssen, U. Sainju, T. Caesar-Tonthat, B. Allen, R. Lartey
Farming Systems Research On Crop Diversification, Tillage, And Management Effects On Yield, Pests, And Environmental Quality In A Semi-Arid Environment, Andrew W. Lenssen, U. Sainju, T. Caesar-Tonthat, B. Allen, R. Lartey
Andrew W. Lenssen
Available water, depleted soil quality, and weed competition are important constraints to crop production in the northern Great Plains. The traditional rotation in the region has been spring wheat with summer fallow, which is used to accrue additional soil moisture for the subsequent wheat crop. Tillage during fallow periods controls weeds, which otherwise would use substantial amounts of water and inorganic nitrogen, decreasing the efficiency of fallow and increasing soil erosion. Chemical fallow and zero tillage systems improve soil water status for subsequent crops (Lenssen et al., 2007a), allowing for increased cropping intensity and improved nutrient cycling (Lenssen et al., …
Sheep Grazing Wheat Summer Fallow And The Impact On Soil Nitrogen, Moisture, And Crop Yield, Andrew W. Lenssen, E. E. Snyder, H. B. Goosey, P. G. Hatfield
Sheep Grazing Wheat Summer Fallow And The Impact On Soil Nitrogen, Moisture, And Crop Yield, Andrew W. Lenssen, E. E. Snyder, H. B. Goosey, P. G. Hatfield
Andrew W. Lenssen
In typical dryland farming areas of Montana, annual precipitation is not sufficient for annual harvest of small grains. Summer fallow in alternate years, is a common method of conserving soil moisture to produce a crop in the following season. Current methods of fallow management are primarily mechanical tillage and spraying with herbicides. Although these methods are effective, they are expensive, making fallow management the highest variable cost associated with dryland grain production. The objectives of this study were to compare the impact of grazing small grains stubble with sheep, as a fallow management tactic, against traditional management practices of chemical …
Carbon Sequestration In Dryland Soils And Plant Residue As Influenced By Tillage And Crop Rotation, Andrew W. Lenssen, Upendra M. Sainju, Thecan Caesar-Thonthat, Jed Waddell
Carbon Sequestration In Dryland Soils And Plant Residue As Influenced By Tillage And Crop Rotation, Andrew W. Lenssen, Upendra M. Sainju, Thecan Caesar-Thonthat, Jed Waddell
Andrew W. Lenssen
Long-term use of conventional tillage and wheat (Triticum aestivum L.)–fallow systems in the northern Great Plains have resulted in low soil organic carbon (SOC) levels. We examined the effects of two tillage practices [conventional till (CT) and no-till (NT)], five crop rotations [continuous spring wheat (CW), spring wheat–fallow (W–F), spring wheat–lentil (Lens culinaris Medic.) (W–L), spring wheat–spring wheat–fallow (W–W–F), and spring wheat–pea (Pisum sativum L.)–fallow (W–P–F)], and Conservation Reserve Program (CRP) planting on plant C input, SOC, and particulate organic carbon (POC). A field experiment was conducted in a mixture of Scobey clay loam (fine-loamy, mixed, Aridic Argiborolls) and Kevin …
Cropping Sequence And Tillage System Influences Annual Crop Production And Water Use In Semiarid Montana, Usa, Andrew W. Lenssen, G. D. Johnson, G. R. Carlson
Cropping Sequence And Tillage System Influences Annual Crop Production And Water Use In Semiarid Montana, Usa, Andrew W. Lenssen, G. D. Johnson, G. R. Carlson
Andrew W. Lenssen
Available water is typically the biggest constraint to spring wheat production in the northern Great Plains of the USA. The most common rotation for spring wheat is with summer fallow, which is used to accrue additional soil moisture. Tillage during fallow periods controls weeds, which otherwise would use substantial amounts of water, decreasing the efficiency of fallow. Chemical fallow and zero tillage systems improve soil water conservation, allowing for increased cropping intensity. We conducted a field trial from 1998 through 2003 comparing productivity and water use of crops in nine rotations under two tillage systems, conventional and no-till. All rotations …
Tillage And Crop Rotation Effects On Dryland Soil And Residue Carbon And Nitrogen, Upendra M. Sainju, Andrew W. Lenssen, Thecan Caesar-Tonthat, Jed Waddell
Tillage And Crop Rotation Effects On Dryland Soil And Residue Carbon And Nitrogen, Upendra M. Sainju, Andrew W. Lenssen, Thecan Caesar-Tonthat, Jed Waddell
Andrew W. Lenssen
Sustainable management practices are needed to enhance soil productivity in degraded dryland soils in the northern Great Plains. We examined the effects of two tillage practices [conventional till (CT) and no-till (NT)], five crop rotations [continuous spring wheat (Triticum aestivum L.) (CW), spring wheat-fallow (W-F), spring wheat-lentil (Lens culinaris Medic.) (W-L), spring wheat-spring wheat-fallow (W-W-F), and spring wheat-pea (Pisum sativum L.)-fallow (W-P-F)], and a Conservation Reserve Program (CRP) on plant biomass returned to the soil, residue C and N, and soil organic C (SOC), soil total N (STN), and particulate organic C and N (POC and PON) at the 0- …
Incorporating Targeted Grazing Into Farming Systems, Andrew W. Lenssen, Patrick Hatfield, Hayes Goosey, Sue Blodgett
Incorporating Targeted Grazing Into Farming Systems, Andrew W. Lenssen, Patrick Hatfield, Hayes Goosey, Sue Blodgett
Andrew W. Lenssen
When incorporating targeted grazing into farming systems, livestock producers and farm operators need assurance that the benefits from their activities are worth their investments. This chapter will focus on how integrating grazing, particularly with sheep and goats, into farming systems can offer those benefits. The concepts are not new. Cropping systems were once integrated with livestock production: Livestock gained forage value from crop aftermath, crops were grown to sustain livestock, and livestock were used as implements to produce crops. Today, few cropping systems include livestock. Sheep and goats are traditionally produced on rangelands or pasture forages and supplemented during winter …
Density And Diversity Of Overwintering Birds In Managed Field Borders In Mississippi, Stephen J. Dinsmore, Mark D. Smith, Philip J. Barbour, L. Wes Burger Jr.
Density And Diversity Of Overwintering Birds In Managed Field Borders In Mississippi, Stephen J. Dinsmore, Mark D. Smith, Philip J. Barbour, L. Wes Burger Jr.
Stephen J Dinsmore
Grassland bird populations are sharply declining in North America. Changes in agricultural practices during the past 50 years have been suggested as one of the major causes of this decline. Field-border conservation practices encouraged by the U.S. Department of Agriculture's National Conservation Buffer Initiative meet many of the needs of sustainable agriculture and offer excellent opportunities to enhance local grassland bird populations within intensive agricultural production systems. Despite the abundant information on avian use of, and reproductive success in, strip habitats during the breeding season, few studies have examined the potential value of field borders for wintering birds. We planted …
The Potential Role Of Sheep In Dryland Grain Production Systems, H. B. Goosey, P. G. Hatfield, Andrew W. Lenssen, Sue L. Blodgett, R. W. Kott
The Potential Role Of Sheep In Dryland Grain Production Systems, H. B. Goosey, P. G. Hatfield, Andrew W. Lenssen, Sue L. Blodgett, R. W. Kott
Andrew W. Lenssen
In dryland farming areas of Montana, annual precipitation is not sufficient for annual planting of cereal grains. Instead, a crop-summer fallow farming system is used to conserve soil moisture and increase available nitrogen for subsequent crop growth. Managing this summer fallow, either by mechanical means or with herbicides, is the highest variable cost associated with dryland grain production in Montana. Wheat stem sawfly, Cephus cinctus (Hymenoptera: Cephidae) is the most damaging insect pest to Montana’s US$ 1 billion per year grain industry. Weed management is the largest variable cost associated with dryland grain production and summer fallow management. Six fields, …
Effects Of Elevated Co2 On The Response Of Phleum Pratense And Poa Pratensis To Aboveground Defoliation And Root-Feeding Nematodes, Brian J. Wilsey
Effects Of Elevated Co2 On The Response Of Phleum Pratense And Poa Pratensis To Aboveground Defoliation And Root-Feeding Nematodes, Brian J. Wilsey
Brian J. Wilsey
Because of the importance of herbivory in many herbaceous plant–dominated ecosystems, it will be important to determine whether interactions exist between herbivory and CO2 enrichment if we are to understand better how ecosystems will respond to global change. In an experiment with the C3 grasses Poa pratensis and Phleum pratense, plants were grown together under ambient (360 ppm) and elevated (650 ppm) CO2, with and without aboveground defoliation, and with or without additions of the root-feeding nematode Pratylenchus penetrans. The objective was to determine whether herbivory would interact with CO2 enrichment in determining biomass responses or whether these factors were …
Yponomeuta Evonymellus Outbreaks In Southern Finland: Spatial Synchrony But Different Local Magnitudes, Brian J. Wilsey, Conchita Alonso, Timo Vuorisalo, Tuija Honkanen
Yponomeuta Evonymellus Outbreaks In Southern Finland: Spatial Synchrony But Different Local Magnitudes, Brian J. Wilsey, Conchita Alonso, Timo Vuorisalo, Tuija Honkanen
Brian J. Wilsey
Defoliations of Prunus padus by Yponomeuta evonymellus were monitored in two areas in southern Finland. During a long-term study (1980–1995) in the area with high peak defoliations, P. padus trees recorded two defoliation peaks, leading to complete defoliation of many trees. The negative relationship between pupal mass and current year tree defoliation during the peak years suggested shortage of food affected reproductive potential of Y. evonymellus. Furthermore, no delayed induced resistance was observed in these populations. Interannual correlations in degrees of defoliation experienced by individual trees were low, i.e. high defoliation in one year did not predict the degree of …
Biodiversity And Ecosystem Functioning: Importance Of Species Evenness In An Old Field, Brian J. Wilsey, Catherine Potvin
Biodiversity And Ecosystem Functioning: Importance Of Species Evenness In An Old Field, Brian J. Wilsey, Catherine Potvin
Brian J. Wilsey
Changes in land use, habitat fragmentation, nutrient enrichment, and environmental stress often lead to reduced plant diversity in ecosystems. However, it remains controversial whether these reductions in diversity will affect energy flow and nutrient cycling. Diversity has two components: species richness, or the number of plant species in a given area, and species evenness, or how well distributed abundance or biomass is among species within a community. We experimentally varied species evenness and the identity of the dominant plant species in an old field of Quebec to test whether plant productivity would increase with increasing levels of evenness, and whether …
Effects Of Elevated Co2 And Defoliation On Grasses: A Comparative Ecosystem Approach, Brian J. Wilsey, James S. Coleman, Samuel J. Mcnaughton
Effects Of Elevated Co2 And Defoliation On Grasses: A Comparative Ecosystem Approach, Brian J. Wilsey, James S. Coleman, Samuel J. Mcnaughton
Brian J. Wilsey
Three plant species from each of three grassland ecosystems were grown under elevated (700 mL/m3) and ambient (350 mL/m3) CO2 and were defoliated or left undefoliated to test whether species response to elevated CO2 and grazing is related to evolutionary grazing history or to mode of photosynthesis. The three ecosystems represented a tropical grassland dominated by C4 species (the Serengeti of Africa), a temperate grassland dominated by a mixture of C3 and C4 species (Flooding Pampa of South America), and a northern temperate grassland dominated by C3 species (Yellowstone National Park of North America). Plants were grown in growth chambers …
Clonal-By-Environment Interactions Influence Isoflavonoid Accumulation In Cicer Milkvetch, Andrew W. Lenssen, C. E. Townsend, S. S. Martin
Clonal-By-Environment Interactions Influence Isoflavonoid Accumulation In Cicer Milkvetch, Andrew W. Lenssen, C. E. Townsend, S. S. Martin
Andrew W. Lenssen
Cicer milkvetch (Astragalus cicer L.) is a perennial, nonbloatinducing forage legume adapted to temperate environments. For unknown reasons, however, ruminants grazing cicer milkvetch in pure stands have become photosensitized, or sunburned, in some environments, Isoflavonoids are involved with diverse biological activities, including estrogenism, disease resistance, and, potentially, photosensitization. We conducted a series of studies from 1991 to 1993 to identify factors that influence the accumulation of isoflavonoids. In separate greenhouse studies, elicited leaflets from the parental clones of ‘Monarch’ and. ‘Windsor’ cicer milkvetch were analyzed for isoflavonoid accumulation. Growth chamber studies were conducted to investigate the clonal variability of leaflet …
Influence Of Summer Storms On The Solution Geochemistry In A Coastal Plain Hydrosequence, Jeffrey M. Novak, C. Lee Burras
Influence Of Summer Storms On The Solution Geochemistry In A Coastal Plain Hydrosequence, Jeffrey M. Novak, C. Lee Burras
C. Lee Burras
An understanding of factors which influence wetland soil solution chemistry is important for soil solutions are known to influence some chemical properties of surface waters. The influence of summer storms on the solution geochemistry in a South Carolina riverine wetland soil was evaluated by comparing pore water collected 2,4 hr after five summer storm events with pore water acquired during five nonstorm periods. Pore water was collected by tension lysimeters buried at 15 to 152 cm in two locations along a hydrologic gradient. Samples of rain, throughfall and stream water were also collected. Overall, summer storms had no significant influence …
Induced Lsoflavonoids In Diverse Populations Of Astragalus Cicer, Andrew W. Lenssen, Susan S. Martin, Charley E. Townsend
Induced Lsoflavonoids In Diverse Populations Of Astragalus Cicer, Andrew W. Lenssen, Susan S. Martin, Charley E. Townsend
Andrew W. Lenssen
lsoflavonoids were induced in mature leaves of the legume Asbagalus cicer L. by spores of the fungus Bipoaris zeicola. The five major elicited compounds included two isoflavans (mucronulatol and astraciceran), two isoflavones (cajanin and acicerone), and a pterocarpan (maackiain). Only occasional traces of these compounds were detected in controls. Among 41 populations originating in Europe or Russia, mean total elicited isoflavonoid content differed 12-fold. Mucronulatol was the predominant compound elicited, comprising 20-70% of total isoflavonoids. Significant interpopulational differences existed for each isoflavonoid, but no geographic patterns of total or relative proportions of the five compounds were discernible.
Acicerone: An Isoflavone From Astragalus Cicer, Andrew W. Lenssen, Susan S. Martin, Charley E. Townsend, Bruce Hawkins
Acicerone: An Isoflavone From Astragalus Cicer, Andrew W. Lenssen, Susan S. Martin, Charley E. Townsend, Bruce Hawkins
Andrew W. Lenssen
A new isoflavone isolated from fungus-inoculated roots of Astragalus cicer has been identified as 6-hydroxy- 7-methoxy-3’,4’-methylenedioxyisoflavone (acicerone).
Forage Yield, Quality, Compatibility, And Persistence Of Warm-Season Grass—Legume Mixtures, G. L. Posler, Andrew W. Lenssen, G. L. Fine
Forage Yield, Quality, Compatibility, And Persistence Of Warm-Season Grass—Legume Mixtures, G. L. Posler, Andrew W. Lenssen, G. L. Fine
Andrew W. Lenssen
Development of compatible, persistent, warm-season grass-legume mixtures could increase forage yield and quality during summer months. We established a trial to determine forage yield, quality, species compatibility, and persistence of binary mixtures of warm-season grasses with selected legumes, five of which are native to the central USA. Grass entries were switchgrass (Panicum virgatum L.), sideoats grama (Bouteloua curtipendula Michx.), and indiangrass [Sorghastrum nutans (L.) Nash]. Legume entries were purple prairieclover [Dalea purpurea Vent.; syn. Petalostemon purpureum (Vent.) Rydb.], roundhead lespedeza (Lespedeza capitata Michx.), leadplant (Amorpha canescens Pursh), Illinois bundleflower [Desmanthus illinoensis (Michx.) MacMill., B. Robins. & Fern.], catclaw sensitive brier …
Diversity Among Rhizobia Effective With Robinia Pseudoacacia L, Janet Mccray-Batzli, William R. Graves, Peter Van Berkum
Diversity Among Rhizobia Effective With Robinia Pseudoacacia L, Janet Mccray-Batzli, William R. Graves, Peter Van Berkum
William R Graves
The diversity of rhizobia that form symbioses with roots of black locust (Robinia pseudoacacia L.), an economically important leguminous tree species, was examined by inoculating seedling root zones with samples of soil collected from the United States, Canada, and China. Bacteria were isolated from nodules, subcultured, and verified to be rhizobia. The 186 isolates varied significantly in their resistance to antibiotics and NaCl, their growth on different carbohydrates, and their effect on the pH of culture media. Most isolates showed intermediate antibiotic resistance, the capacity to use numerous carbohydrates, and a neutral to acid pH response. Isolates had greater similarity …