TY - JOUR TI - Intra- and inter-specific density affects plant growth responses to arbuscular mycorrhizas AU - Schroeder-Moreno, Michelle S. AU - Janos, David P. T2 - BOTANY AB - Arbuscular mycorrhizas can alter competitive interactions between plants that markedly differ in their dependence upon mycorrhizas, but little is known about how mycorrhizas affect intra- and inter-specific competition between similarly dependent plant species. We conducted competition experiments in pots between all pairs of the similarly facultatively mycotrophic crop species, chili ( Capsicum annuum L.), maize ( Zea mays L.), and zucchini ( Cucurbita pepo L.). We used a two-species yield-density model to analyze the separate effects of mycorrhizal inoculation, intra-, and inter-specific density on biomass responses. Mycorrhizas reduced the growth of all three plant species. Intraspecific competition increased the negative effect of mycorrhizas, as did interspecific competition at low intraspecific density. At high intraspecific density, however, interspecific competition improved plant responsiveness to mycorrhizas. Enhancement of plant benefit from mycorrhizas at high interspecific density of competing, weakly mycorrhiza-dependent species may help to explain the evolutionary maintenance of their associations with mycorrhizal fungi, and may be a key to understanding intercrop combinations that exceed the monoculture yields of component species. DA - 2008/10// PY - 2008/10// DO - 10.1139/B08-080 VL - 86 IS - 10 SP - 1180-1193 SN - 1916-2804 KW - intraspecific competition KW - interspecific competition KW - facilitation KW - arbuscular mycorrhizas KW - facultative mycotrophs KW - yield-density model ER - TY - JOUR TI - Nutrient management with cover crops and compost affects development and yield in organically managed sweetpotato systems AU - Treadwell, D. D. AU - Creamer, N. G. AU - Hoyt, G. D. AU - Schultheis, J. R. T2 - HortScience DA - 2008/// PY - 2008/// VL - 43 IS - 5 SP - 1423-1433 ER - TY - JOUR TI - Long-term agricultural research: A research, education, and extension imperative AU - Robertson, G. Philip AU - Allen, Vivien G. AU - Boody, George AU - Boose, Emery R. AU - Creamer, Nancy G. AU - Drinkwater, Laurie E. AU - Gosz, James R. AU - Lynch, Lori AU - Havlin, John L. AU - Jackson, Louise E. AU - Pickett, Steward T. A. AU - Pitelka, Louis AU - Randall, Alan AU - Reed, A. Scott AU - Seastedt, Timothy R. AU - Waide, Robert B. AU - Wall, Diana H. T2 - BIOSCIENCE AB - For agriculture to meet goals that include profitability, environmental integrity, and the production of ecosystem services beyond food, fuel, and fiber requires a comprehensive, systems-level research approach that is long-term and geographically scalable. This approach is largely lacking from the US agricultural research portfolio. It is time to add it. A long-term agricultural research program would substantially improve the delivery of agricultural products and other ecosystem services to a society that calls for agriculture to be safe, environmentally sound, and socially responsible. DA - 2008/// PY - 2008/// DO - 10.1641/B580711 VL - 58 IS - 7 SP - 640-645 SN - 0006-3568 KW - agriculture KW - long-term research KW - sustainability KW - LTER KW - agricultural extension and education ER -