Chloroplast genome resources and molecular markers differentiate rubber dandelion species from weedy relatives

Rubisco large subunit genes (rbcL) from the Asteraceae. (DOCX 29 kb

Implications of Climate Change for Agricultural Pest Management

Termination ReportThe University Archives has determined that this item is of continuing value to OSU's history.The thermal requirements of crops and insect pests differ significantly; their differential thermal requirements will govern how climate change impacts pest management needs and practices. To investigate the impact of climate change on pest management and the implications for farming communities, we have connected EPIC, a field-scale crop management model, with a temperature-driven model of insect population development (GILSM). EPIC was used to model the corn and soybean rotation common in the Midwest, and GILSM was programmed to model the growth of nine insect pests of corn and/or soybeans. Output from the model system was input to a geographic information system covering the eight-state corn-belt (Indiana, Illinois, Iowa, Kansas, Kentucky, Missouri, Nebraska and Ohio). The models were driven using GFDL-CM2 climate scenario data developed for the period 1901-2100 as part of NOA and IPCC investigations of global climate change. Over the past 100 years, crop productivity has increased several fold as a result of improved cultivation methods, fertilizers and pesticides, and plant breeding. In order to remove the confounding of changes in technology and possible climate change over the past century and unknown changes to come in the next century, a standard crop production protocol was used from 1901-2100. Using the crop production practices used most commonly in 2000 (the midpoint of the period), EPIC/GILSM was run for four 50 year periods (1901-1950, 1951-2000, 2001-2050 and 2051-2100) and the changes in crop yield and insect abundance were examined between periods. Nine insect pests found throughout the region were modeled to examine the range of likely responses of insect pests to climate change and the possible change in crop protection needs over the next 100 years. As expected, the model predicted little or no change between the first and second periods. For most species, change was maximum in the third period and less during the fourth period. In every case the isoclines for pest population density and crop productivity moved northwards, but at different rates, resulting in the isoclines for crop damage increasing as they moved northward. In two cases the pest abundance declined locally even as productivity increased, resulting in a net increase in productivity. No allowance was made for changes in agronomic practices or improvements in breeding pest resistance, both of which have helped to improve productivity over the past century.SEEDS-The OARDC Research Enhancement Competitive Grants Program: Interdisciplinary Team Research Competitio

Weed Seed Bank Emergence across the Corn Belt

Field experiments, conducted from 1991 to 1994, generated information on weed seedbank emergence for 22 site-years from Ohio to Colorado and Minnesota to Missouri. Early spring seedbank densities were estimated through direct extraction of viable seeds from soil cores. Emerged seedlings were recorded periodically, as were daily values for air and soil temperature, and precipitation. Percentages of weed seedbanks that emerged as seedlings were calculated from seedbank and seedling data for each species, and relationships between seedbank emergence and microclimatic variables were sought. Fifteen species were found in 3 or more site-years. Average emergence percentages (and coefficients of variation) of these species were as follows: giant foxtail, 31.2 (84%); velvetleaf, 28.2 (66); kochia, 25.7 (79); Pennsylvania smartweed, 25.1 (65); common purslane, 15.4 (135); common ragweed, 15.0 (110); green foxtail, 8.5 (72); wild proso millet, 6.6 (104); hairy nightshade, 5.2 (62); common sunflower, 5.0 (26); yellow foxtail, 3.4 (67); pigweed species, 3.3 (103); common lambsquarters, 2.7 (111); wild buckwheat, 2.5 (63), and prostrate knotweed, 0.6 (79). Variation among site-years, for some species, could be attributed to microclimate variables thought to induce secondary dormancy in spring. For example, total seasonal emergence percentage of giant foxtail was related positively to the 1st date at which average daily soil temperature at 5 to 10 cm soil depth reached 16 C. Thus, if soil warmed before mid April, secondary dormancy was induced and few seedlings emerged, whereas many seedlings emerged if soil remained cool until June

Local Conditions, Not Regional Gradients, Drive Demographic Variation of Giant Ragweed (Ambrosia trifida) and Common Sunflower (Helianthus annuus) Across Northern U.S. Maize Belt

Knowledge of environmental factors influencing demography of weed species will improve understanding of current and future weed invasions. The objective of this study was to quantify regional-scale variation in vital rates of giant ragweed and common sunflower. To accomplish this objective, a common field experiment was conducted across seven sites between 2006 and 2008 throughout the north central U.S. maize belt. Demographic parameters of both weed species were measured in intra- and interspecific competitive environments, and environmental data were collected within site-years. Site was the strongest predictor of belowground vital rates (summer and winter seed survival and seedling recruitment), indicating sensitivity to local abiotic conditions. However, biotic factors influenced aboveground vital rates (seedling survival and fecundity). Partial least squares regression (PLSR) indicated that demography of both species was most strongly influenced by thermal time and precipitation. The first PLSR components, both characterized by thermal time, explained 63.2% and 77.0% of variation in the demography of giant ragweed and common sunflower, respectively; the second PLSR components, both characterized by precipitation, explained 18.3% and 8.5% of variation, respectively. The influence of temperature and precipitation is important in understanding the population dynamics and potential distribution of these species in response to climate change

Weed Seed Bank Emergence across the Corn Belt

Field experiments, conducted from 1991 to 1994, generated information on weed seedbank emergence for 22 site-years from Ohio to Colorado and Minnesota to Missouri. Early spring seedbank densities were estimated through direct extraction of viable seeds from soil cores. Emerged seedlings were recorded periodically, as were daily values for air and soil temperature, and precipitation. Percentages of weed seedbanks that emerged as seedlings were calculated from seedbank and seedling data for each species, and relationships between seedbank emergence and microclimatic variables were sought. Fifteen species were found in 3 or more site-years. Average emergence percentages (and coefficients of variation) of these species were as follows: giant foxtail, 31.2 (84%); velvetleaf, 28.2 (66); kochia, 25.7 (79); Pennsylvania smartweed, 25.1 (65); common purslane, 15.4 (135); common ragweed, 15.0 (110); green foxtail, 8.5 (72); wild proso millet, 6.6 (104); hairy nightshade, 5.2 (62); common sunflower, 5.0 (26); yellow foxtail, 3.4 (67); pigweed species, 3.3 (103); common lambsquarters, 2.7 (111); wild buckwheat, 2.5 (63), and prostrate knotweed, 0.6 (79). Variation among site-years, for some species, could be attributed to microclimate variables thought to induce secondary dormancy in spring. For example, total seasonal emergence percentage of giant foxtail was related positively to the 1st date at which average daily soil temperature at 5 to 10 cm soil depth reached 16 C. Thus, if soil warmed before mid April, secondary dormancy was induced and few seedlings emerged, whereas many seedlings emerged if soil remained cool until June

Validazione di Piani di Disaster Recovery mediante Simulatore

Contribution published online at: http://www.mimos.it/nuovo/contenuto_view.asp?check=10