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nÃo hà / Avaliou-se os efeitos de diferentes lÃminas de irrigaÃÃo e doses de nitrogÃnio (N) sobre as caracterÃsticas morfogÃnicas e estruturais, produÃÃo e composiÃÃo quÃmicobromatolÃgica dos capins Andropogon gayanus cv. Planaltina e Brachiaria brizantha cv. Marandu. O estudo foi conduzido no perÃodo de agosto a dezembro de 2007, na Unidade de ExecuÃÃo de Pesquisa da EMBRAPA Meio-Norte, localizada no municÃpio de ParnaÃba, PiauÃ. Os tratamentos consistiram em duas lÃminas de irrigaÃÃo (equivalente à reposiÃÃo de 50% e 80% da EvaporaÃÃo do Tanque Classe A - ECA) e quatro doses de nitrogÃnio (equivalente a 200, 400, 600 e 800 kg de N/ha x ano), em um delineamento em blocos casualizados, em esquema fatorial 2 x 4, com trÃs repetiÃÃes. As parcelas experimentais mediam 3 m x 8 m, sendo realizado um corte de uniformizaÃÃo (agosto) e quatro cortes para coleta de dados a cada 30 dias, a 20 cm do solo. Em geral, nos capins estudados, a reduÃÃo da lÃmina de irrigaÃÃo, proporcionou decrÃscimos nas taxas de alongamento da folha e do colmo, aparecimento de folha, comprimento final da folha e nÃmero de folhas vivas, enquanto que, taxa senescÃncia aumenta e duraÃÃo de vida de folhas à pouco afetada. A adubaÃÃo nitrogenada aumentou as taxas de alongamento da folha e do colmo, aparecimento de folha e comprimento final da folha. Contudo, tendeu a reduzir o nÃmero e a duraÃÃo de vida das folhas, e a ampliar a taxa senescÃncia. As lÃminas aplicadas apresentaram comportamentos semelhantes em relaÃÃo à produtividade de matÃria seca total e de folhas. Todavia, a lÃmina de 80% de ECA proporcionou as maiores alturas de plantas e menor relaÃÃo folha/colmo. A maior lÃmina de irrigaÃÃo promoveu aumentos da produÃÃo de colmo, porÃm nÃo afetou a produÃÃo de folhas. Em geral a adubaÃÃo nitrogenada influenciou positivamente a produtividade de matÃria seca total, de folhas e colmos, mas, diminuiu a eficiÃncia de utilizaÃÃo do nitrogÃnio e relaÃÃo folha/colmo. As lÃminas de irrigaÃÃo nÃo afetaram os teores de matÃria seca (MS) das folhas do capimandropogon. A maior lÃmina de irrigaÃÃo promoveu reduÃÃo expressiva dos teores de MS da folha do capim-marandu e colmo das duas gramÃneas. A adubaÃÃo nitrogenada nÃo afetou os teores de MS do capim-andropogon. No entanto, nas folhas do capimmarandu os teores de MS decresceram inversamente proporcional aos nÃveis de nitrogÃnio aplicado. Os teores de proteÃna das duas gramÃneas nÃo foram influenciados pelas lÃminas de irrigaÃÃo. A adubaÃÃo nitrogenada aumentou linearmente os teores de proteÃna das folhas e dos colmos. A utilizaÃÃo da maior lÃmina promoveu incrementos nos teores de FDN dos capins estudados. Os teores de FDN foram inversamente proporcionais aos nÃveis de adubaÃÃo. Os teores de FDA sofreram influÃncia negativa da maior lÃmina de irrigaÃÃo. Os nÃveis de adubaÃÃo nitrogenada promoveram decrÃscimos nos nÃveis de FDA. Em geral, a adubaÃÃo nitrogenada promoveu melhoria no valor nutritivo do capim-marandu. / The objective of this work was to evaluate the effects of different irrigation and doses of nitrogen on the morphogenetic and structural characteristics, forage production and bromatologic composition of Andropogon gayanus var. Planaltina and Brachiaria brizantha var. Marandu. The study was conducted from August to December 2007 on Unit Research of EMBRAPA Meio-Norte, located in city of ParnaÃba, PiauÃ, Brazil. The treatments consisted of two irrigation levels (with a equivalent level to replacement of 50% and 80% of evaporation of the Class A pan - ECA) and four doses of nitrogen (equivalent to 200, 400, 600 and 800 N/ha x year), in a completely randomized block design in a 2 x 4 factorial design with three replications. The plots measuring 3 m x 8 m, and made a cut of uniformity (in August) and four cuts to collect data every 30 days, at 20 cm the soil. In general, in grass Andropogon and Marandu, the reduction of the irrigation level, provides decreases in leaf elongation and stem elongation rate, leaf appearance and final leaf length, whereas, leaf senescence rate increases and duration of life of leaf little is affected. Leaf senescence rate of grass tended to increase ahead of the lesser water availability of the ground. The nitrogen fertilization increases the rates of elongation e leaf and stem, leaf appearance and final length of the leaf. However, it tends to reduce the number it and the duration of life of the leaf, and to extend rate senescence. The applied irrigation levels presented similar behaviors in relationship of productivity of total dry matter and of leaves. Though the level of 80% of ECA provided the largest heights of plants and smaller relation leaf/stem ratio. The largest irrigation level promoted increases of the production of stem, even so it didn't affect the production of leaves. In general the nitrogen fertilization influenced the productivity of total dry matter positively, of leaves and stem, however, it decreased the efficiency of use of the nitrogen and relation leaf/stem ratio. Increasing doses of nitrogen reduces the dry matter at the same time as the irrigation level of 80% decreasing these values, both for the leaf and to stem fraction. The irrigation level of 80% decreases the crude protein 18 contents, both for the leaf and to stem at the same time it increases the levels of ADF both for the leaf and to stem. The irrigation levels didn't affect the content of dry matter of the Andropogon grass. The largest irrigation level (80% of ECA) it promoted expressive reduction of the level of DM of the leaf of the Marandu grass and the stem of both grasses. The fertilization nitrogen didn't affect the texts of DM of the Andropogon grass. Though, in the leaves of the Marandu grass the content of DM decreased inversely in way proportional at the levels of applied nitrogen. The contents protein of the researched grasses was not influenced by the applied irrigation levels. The fertilization nitrogen increased the contents of protein of the leaves lineally and stems, and the largest texts were obtained with the applications of 600 and 800 kg the N/ha x year. The interaction fertilization nitrogen x irrigation levels increased the contents of NDF of the leaves of the Andropogon grass. The use of the largest level (80% of ECA) it promoted increments in the contents of NDF of the studied grasses. Though, the contents of NDF went inversely proportional at the fertilization levels. The contents of ADF suffered it influences negative of the largest irrigation level. The doses of fertilization nitrogen promoted decreases in the levels of FDA. In general, the fertilization nitrogen improvement in the nutritious value of Marandu grass

This investigation has been made with reference to the adaptability of Andropogon ischaemum, King Ranch bluestem, to various soils, various slopes, and various erosion conditions in Denton County.

Thesis (Ph. D.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains vii, 146 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 126-145).

Thesis (Ph.D.)--Michigan State University. Dept. of Crop and Soil Sciences, 2008. / Title from PDF t.p. (viewed on July 9, 2009) Includes bibliographical references. Also issued in print.

The restoration of degraded tallgrass prairies can mitigate climate change due to the carbon accrued during the development of grasslands. The focal species, dominant grass Andropogon gerardii, can assist the recovery of grassland ecosystem functioning. Climate, local adaptation, and biodiversity have been found to impact the accrual of carbon in grasslands. This study examined the difference in ecosystem functioning between ecotypes along a dry to mesic precipitation scale. The study site for this project was at the Southern Illinois University Agriculture Research Center in Carbondale, Illinois. The field site was planted with seeds originating from dry to mesic ecotypes, and the resulting ecosystem functioning was analyzed. It was found that the Kansas non-local ecotypes had significantly higher biodiversity, while the local Illinois sites demonstrated local adaptation with A. gerardii. Aboveground plant biomass was higher in the local sites, but there was no difference in carbon accrual between any of the ecotypes. While ecotypic variation in a dominant species will usually differentially influence ecosystem functioning, in this case, high biodiversity and local adaptation result in similar carbon inputs in grassland soil. It is necessary to analyze the carbon content of the soil in the drier field sites in order to determine if major differences in rainfall leads to differences in carbon accrual. If the goal of restoring a tallgrass prairie in southern Illinois is to assist with climate change mitigation, then it does not make a significant difference if the dominant species is sourced locally or non-locally.

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Call number: LD2668 .T4 1978 A54 / Master of Science

Call number: LD2668 .T4 1979 P482 / Master of Science

Wide-scale conversion of tallgrass prairie to row-crop agriculture has spurred restoration of this endangered ecosystem. At the onset of restoration, a matrix of native plant species is sown into former crop field and includes warm-season (C4) grasses, cool-season (C3) grasses, legumes, and a large variety of herbaceous forbs. Increased demand for native seed due to a greater number of areas targeted for restoration has increased use of C4 grass cultivars by restoration practitioners. Cultivars are selectively bred to display traits such as increased productivity and digestibility, thus highlighting their original use in rangelands of the Great Plains. C4 grasses have a mutualistic relationship with arbuscular mycorrhizal fungi (AMF). In remnant tallgrass prairie, AMF can increase C4 plant uptake of belowground resources (e.g., water, soil P) by increasing root surface area. It is unknown if AMF colonization varies between seed source (cultivar or non-cultivar) of C4 grasses used in restoration and if this further affects plant biomass. Intraspecific variation in AMF colonization between two dominant warm-season prairie grasses was tested in two established prairie restoration experiments, both having plots seeded with either C4 cultivars or non-cultivars. To test for effects of seed source and AMF colonization on plant biomass, a greenhouse experiment was designed using two source populations (cultivar and non-cultivar) of two species (Andropogon gerardii Vitman and Sorghastrum nutans (L.) Nash) and soil collected at each field restoration (Kansas and Illinois). To suppress activity and colonization of AMF, a fungicide (Allban Flo: Thiophanate Methyl) was applied to half of the containers. Warm-season (C4) grass cultivars had greater or equivalent biomass production than non-cultivars at the onset of field restoration and also in the greenhouse. Furthermore, cultivars generally had less or equivalent root colonization by AMF and dependence on fungicide-free soil was greater in cultivars to retain increased accrual of biomass. It was, however, not possible to determine the role of AMF in plant biomass production as fungicide did not successfully reduce AMF root colonization in cultivars or non-cultivars, with one exception. It is critical that an effective AMF-suppression treatment be established in these types of studies. Future experiments should validate supposed effectiveness of the newly-recommended fungicide (Topsin-M) in population sources of warm-season prairie grasses and also apply it to the soil at time of planting in greenhouse studies. In the field sites, adjacent soil cultivation may have contributed to greater AMF biomass more so than surrounding remnant prairie. Future research identifying species composition of AMF at these sites is necessary to clarify differences in biomass. Despite greater plant biomass in cultivars, soil nutrient availability remained equivalent between source populations in general. Available N and P were not less in soils grown with cultivars, however soil inorganic N was inversely related to root length colonized by AMF, suggesting a role of AMF in N transfer from soil to plant. Soil P was not different between source populations likely due to legacy effects of agricultural fertilization, thus limiting a well known benefit of AMF symbiosis, at least at the onset of restoration. Non-target effects of fungicide application were observed (e.g., changes in available N) and effectiveness of AMF suppression was questionable. Fungicide lowered pH and increased N availability in soil as indicated by main effects of application and a positive relationship between pH and inorganic N across species. Fungicide application either 1) decreased N uptake by soil microorganisms (possibly including AMF) or 2) increased competition for adsorption sites and/or solubility of total inorganic N as pH changed, thus making this nutrient more available in the soil solution. Future examination quantifying indirect effects of fungicide application on soil chemistry should also be considered to better elucidate role of AMF in plant growth and soil nutrient availability between cultivars and non-cultivars of warm-season grasses used in tallgrass prairie restoration.