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Douds Jr. D.D.,U.S. Department of Agriculture | Nagahashi G.,U.S. Department of Agriculture | Wilson D.O.,Rodale Institute | Wilson D.O.,Kings Agriseeds Inc. | Moyer J.,Rodale Institute
Plant and Soil | Year: 2011

Producing nonmycorrhizal plants in the field is a challenge due to the ubiquitous distribution of arbuscular mycorrhizal [AM] fungi and impacts of chemical treatments upon nontarget organisms. A field plot was covered with ground cover fabric to prohibit plant growth and take advantage of the obligate symbiotic nature of AM fungi to selectively starve and remove them from the soil microbiological community. The decline in the AM fungus population was monitored through spore counts and most probable number bioassays. Response to inoculation experiments were conducted to contrast the response of Allium porrum L. to inoculation with in vitro produced spores of Glomus intraradices Schenck and Smith when plants were grown in the AM fungus-depleted soil vs. soil from an adjacent, cropped plot. Data indicated a strongly diminished, yet still viable population of AM fungi after 39 months of bare fallow. Plants grown in cropped soil showed no growth response nor increase in percentage root length colonized as a result of inoculation, while the response to inoculation of plants grown in the covered soil increased as the population of AM fungi declined below 1 propagule cm-3. © 2010 Springer Science+Business Media B.V. (outside the USA). Source

Douds D.D.,U.S. Department of Agriculture | Wilson D.O.,Rodale Institute | Wilson D.O.,Kings Agriseeds Inc. | Seidel R.,Rodale Institute | And 2 more authors.
Scientia Horticulturae | Year: 2016

A preliminary greenhouse growth phase prior to outplanting allows for earlier stand establishment and the greater profits that early-harvested crops can receive. Inoculation of these crops with arbuscular mycorrhizal [AM] fungi would help combat the effects of low soil temperatures upon phosphorus uptake and establishment of mycorrhizas in the field. Significant establishment of mycorrhizas on roots of sweet corn (Zea mays L.) in the greenhouse is constrained by the approximate two week residence time. Experiments were conducted to examine the benefits of a one week incubation of inoculated potting media at greenhouse temperatures prior to sowing Z. mays seeds upon subsequent development of mycorrhizas. Resulting levels of colonization of roots were contrasted to those of seedlings grown in media that received a 4 °C incubation to inhibit spore germination prior to sowing seeds. Levels of AM fungus colonization were compared to those of other seedlings grown in media with a range of inoculum densities. Pre-incubation of inoculated potting media in the greenhouse prior to sowing significantly increased both percentage root length colonized and total root length colonized by AM fungi 2-5 fold at the 9-11 day sampling period over that in media incubated in the cold room prior to sowing. Comparison to colonization levels in plants exposed to a range of inoculum densities showed that warm incubation increased the effective inoculum density an average of 80%. Pre-incubation in the greenhouse of AM fungus inoculated compartmented flats of potting media proved to be an effective way to enhance formation of mycorrhizas and should prove to be an effective tool to enhance the effective potency of inoculated potting media. © 2016 Published by Elsevier B.V. Source

Byron Seeds LLC and Kings Agriseeds Inc. | Date: 2007-06-05

Seeds for agricultural purposes, namely, grass, oats, wheat, pea and alfalfa seeds.

Ryan M.R.,Pennsylvania State University | Mortensen D.A.,Pennsylvania State University | Bastiaans L.,Wageningen University | Teasdale J.R.,U.S. Department of Agriculture | And 5 more authors.
Weed Research | Year: 2010

In a long-term cropping systems trial comparing organically and conventionally managed systems, organic maize production sustained crop yields equal to conventional methods despite higher weed levels. In 2005 and 2006, an experiment nested within the trial was conducted to gain insight into this apparent crop tolerance to weed competition. Density of mixed weed species was experimentally manipulated to achieve a broad range of weed infestation levels. Under standard management conditions, all cropping systems produced equivalent maize yields, even though weedy plant biomass in the organic treatments was between fourfold and sevenfold greater than in the conventionally managed maize. Increased yield capacity, evidenced when plots were maintained weed-free, and enhanced crop competitiveness, were the main pillars of this apparent crop tolerance to weed competition in the organic systems. Increased soil resource availability and a faster relative crop growth rate in the organic systems probably contributed to these factors, which play an important role in buffering crop fitness during years of less than ideal weed control. Simultaneously, the experiment illustrated the poor efficacy of mechanical weed management in the organic systems, which is the main reason organic maize did not out-yield conventional maize under standard management conditions. © 2010 European Weed Research Society. Source

Ryan M.R.,Pennsylvania State University | Curran W.S.,Pennsylvania State University | Grantham A.M.,Rodale Institute | Hunsberger L.K.,University of Maryland Eastern Shore | And 6 more authors.
Weed Science | Year: 2011

Growing enough cover crop biomass to adequately suppress weeds is one of the primary challenges in reduced-tillage systems that rely on mulch-based weed suppression. We investigated two approaches to increasing cereal rye biomass for improved weed suppression: (1) increasing soil fertility and (2) increasing cereal rye seeding rate. We conducted a factorial experiment with three poultry litter application rates (0, 80, and 160 kg N ha -) and three rye seeding rates (90, 150, and 210 kg seed ha -) in Pennsylvania and Maryland in 2008 and 2009. We quantified rye biomass immediately after mechanically terminating it with a roller and weed biomass at 10 wk after termination (WAT). Rye biomass increased with poultry litter applications (675, 768, and 787 g m -2 in the 0, 80, and 160 kg N ha - treatments, respectively), but this increased rye biomass did not decrease weed biomass. In contrast, increasing rye seeding rate did not increase rye biomass, but it did reduce weed biomass (328, 279, and 225 g m -2 in the 90, 150, and 210 kg seed ha - treatments, respectively). In 2009, we also sampled ground cover before rolling and weed biomass and density at 4 WAT. Despite no treatment effects, we found a correlation between bare soil before rolling (%) and weed biomass at 4 WAT. Our results suggest that increased rye seeding rate can effectively reduce weed biomass and that ground cover in early spring can influence weed biomass later in the growing season. Source

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