Research was conducted in the summers of 1985 and 1986 at the University of Arizona Marana Agricultural Center, with the objectives of (1) determining the best intercropping species combination under near optimum irrigation, using three cereals (sorghum (Sorghum bicolor), maize (Zea mays), and pearl millet (Pennisetum americanum) and three legumes (field bean (Phaseolus vulgaris), cowpea (Vigna unguiculata), and soybean (Glycine max) in all combinations, and (2) identifying species genotypes best adapted to intercropping. Results from 1985 determined sorghum x soybean as the most appropriate intercropping combination for the environment of the Marana Agricultural Center. In the 1986 cropping season, three sorghum genotypes (Pioneer 8493, Funks G-522DR, and California IO80H40) were combined with three soybean genotypes (Asgrow A6242, Asgrow A6520, and Rillito), to identify the best genotype combination for intercropping. Both 1985 and 1986 experiments were carried out in a randomized complete block design with four replications. Pearl millet was the cereal with the greatest decrease in yield when intercropped, indicating that this cereal was not a good competitor with legumes. Sorghum was the best cereal competitor with the legumes and soybean was the best legume competitor with the cereals. Among the three sorghum genotypes studied in 1986, only Pioneer 8493 showed higher yield in monocrop whereas the other two genotypes yielded higher in intercropping, indicating some benefit from this system. On the average, all three sorghum genotypes showed intercropping to be advantageous, with high Land Equivalent Ratio values. Soybean genotypes showed drastic decreases in yield when intercropped. Asgrow A6520 soybean had the highest yield in intercropping. Sorghum #3 (California IO80H40) and soybean #3 (Rillito) were chosen as the most appropriate genotypes for intercropping, for the environmental conditions of the study.

The objectives of this study were to evaluate the effects of earlier corn (Zea mays L.) harvest, on corn yield, intercrop growth, and soil N levels, and to evaluate the effects of red clover (Trifolium pratense L.) compared to ryegrass (Lolium multiflorum Lam.) as intercrops on corn yield and soil N levels. / After two years, earlier corn harvest did not result in greater intercrop growth or higher soil N levels compared with later corn harvest and there was no significant soil N contribution by legume intercrops in either harvest period. Thus, no soil N benefit was found from using intercrops in earlier harvest for silage compared to later harvest for grain corn, nor from using red clover compared to ryegrass as an intercrop. / In the early harvested silage system, a quadratic corn yield response to added N suggested that near-maximum corn dry matter yields were obtained at the rate of 140 kg N ha$ sp{-1}$. Maximum total dry matter yields were not obtained in the late harvest grain system in any site-year. Legume and non-legume intercrop species had similar effects on corn yield.

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Thesis (M.S.)--Oregon State University, 1987. / Typescript (photocopy). One mounted photograph. Includes bibliographical references (leaves 63-67). Also available on the World Wide Web.

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No description available.

Five field experiments were conducted to evaluate the relative attractiveness of potential beneficial insectary plants to aphidophagous hover flies and parasitic Hymenoptera and the effectiveness of interplanting selected flowering plants in a broccoli field to enhance biocontrol of the cabbage aphid and green peach aphid. In 1996 we established a preliminary screening trial to begin development of our sampling methods and evaluations of the attractiveness of selected flowering plants to hover flies and parasitic Hymenoptera. In 1997, we conducted a field experiment at the Oregon State University Vegetable Research Farm near Corvallis, OR to assess the relative attractiveness of 11 selected flowering plants to hover flies and parasitic Hymenoptera. Six of these plants were also evaluated for attractiveness to aphidophagous hover flies in two on-farm trials. The experimental design was a complete randomized block design, with four replications at the OSU site, and three replications at the two on-farm sites. Attractiveness of flowering plants to hover flies was assessed by conducting weekly timed observations of feeding frequencies. Associations of parasitic Hymenoptera were assessed by weekly timed vacuum sampling from a fixed area in plots of flowering plants. Attractiveness differed by dates and sites. Among early-season flowering species, Coriandrum sativa (cilantro) was highly attractive to aphidophagous hover flies and Brassica juncea (mustard), Fagopyrum esculentum (buckwheat) and Agastache rugosa (Korean licorice mint) were most attractive to parasitic Hymenoptera. Among late-season flowers, Achillea millefolium (yarrow), Foeniculum vulgare (fennel) and Agastache rugosa (Korean licorice mint) were most attractive to hover flies, but attractiveness to parasitic Hymenoptera did not differ. An on-farm trial was conducted in 1997 at Stahlbush Island Farm near Corvallis, OR. The objective of this trial was to test the hypothesis that interplanting either alyssum (Lobularia maritima), or cilantro (Coriandrum sativa), with broccoli (Brassica oleracea) would attract aphidophagous hover fly adults and parasitic Hymenoptera, enhance oviposition in the adjacent crop, and increase larval predation and parasitism in the adjacent crop, resulting in suppressed cabbage aphid (Brevicoryne brassicae) and green peach aphid (Myzus persicae) populations in the broccoli crop. The predominate hover fly species present were Toxomerus occidentalis and T. marginatus. More adult female T. occidentalis were caught in pan traps in plots with alyssum than in cilantro or control plots. More hover fly eggs were found on broccoli leaves and a higher percent of the aphids present were parasitized by Hymenoptera in plots with alyssum than in cilantro or control plots. However, no differences in aphid intensities were found between treatment and control plots. A comparison between the mean number of hover fly eggs found per broccoli leaf and the mean number of aphid counted per broccoli leaf suggests there is an association between the two. There appears to be an aphid density threshold below which few hover fly eggs are laid. Gravid females were present in the crop from the first sampling date on, yet hover fly eggs were not found in the crop until the second to last sampling date. Our results indicate that the presence of alyssum enhanced hover fly activity, but did not result in increased larval predation on aphids in the crop. In 1997 a survey of hover flies was conducted at each of the four experimental sites. Hover flies were captured with sweep nets. Representative specimens were identified to species by Christian Kassebeer, University of Kiel, Germany and subsequent identifications were made from reference specimens and with taxonomic keys. Twenty species were identified, 16 of which are aphidophagous. At the OSU site and the two on-farm sites, where the relative attractiveness of flowering plants was assessed, the six most common aphidophagous species, collected at all three sites, were: Meliscaeva cinctella, Toxomerus marginatus, T. occidentalis, Sphaerophoria sulphuripes, S. pyrrhina, and Scaeva pyrastri. / Graduation date: 1998

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No description available.

A one year water table management field study was conducted on a Soulanges sandy loam soil in Soulanges county, Quebec. Two controlled water table levels, i.e. 0.5 m and 0.75 m from the soil surface, as well as free outlet conventional drainage treatments were established in monocropped corn (Zea mays L.) and corn intercropped with ryegrass (Lolium multiflorum Lam) plots. / Cropping system showed no significant effects on evapotranspiration, and on soil moisture distribution. It was observed that the 0.5 m and 0.75 m controlled water tables (CWT) provided the same soil moisture trends in both cropping systems. The soil moisture was always higher in controlled water table plots compared to freely drained plots. The water use efficiency of 0.75 m CWT in both cropping systems was high compared to 0.5 m CWT. / The soil moisture contents at three depths were only 2% to 10% less in intercropped plots compared to monocropped plots. The soil moisture was 12 to 13% higher in CWT plots compared to freely drained plots for both cropping systems. The soil moisture in 0.5 m CWT and 0.75 m CWT plots was not significantly different. The average water table levels in monocropped plots were not significantly different from intercropped plots.