Made available in DSpace on 2014-06-11T19:22:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-03-13Bitstream added on 2014-06-13T20:28:29Z : No. of bitstreams: 1 alves_e_me_botfca.pdf: 1692657 bytes, checksum: 4ff23f18cb2cf8f36ac5f030a1aba20e (MD5) / O presente trabalho constou de oito estudos, que foram realizados em casa-de-vegetação, nos quais avaliou-se a seletividade de diferentes herbicidas, aplicados em pré e pós-emergência, em algumas gramíneas forrageiras tropicais: Brachiaria decumbens Stapf cv. Basilisk, Brachiaria brizantha (Hochst) Stapf cv. Marandu, Panicum maximum Jacq cv. Tanzânia e Panicum maximum Jacq cv. Mombaça. Os herbicidas e doses utilizadas, em g i.a /ha, foram: (i) aplicados em pós-emergência, imazethapyr a 50 e 100, metsulfuron-methyl a 1,0 e 2,0, chlorimuron-ethyl a 7,5 e 15, nicosulfuron a 25 e 50, bentazon a 360 e 720, diclofop-metil 140 e 280, fenoxaprop-ethyl a 30 e 60, atrazine 1.500 e 3.000 e ametryne a 625 e 1.250 e (ii) aplicados em pré-emergência, alachlor a 1.680 e 3.360, metolachlor 1.200 e 2.400, diuron a 800 e 1.600, imazaquin a 75 e 150, imazapyr a 250 e 500, imazethapyr a 50 e 100, clomazone a 450 e 900, flumetsulam a 70 e 140, ametryne a 625 e 1.250, metribuzin a 525 e 1.050 e trifluralin a 900 e 1.800, além de testemunha sem aplicação de herbicidas. Utilizou-se delineamento inteiramente casualizado com os tratamentos em seis repetições. O consumo de calda de aplicação foi de 180 L/ha e a barra de aplicação continha quatro bicos de jato plano, tipo Teejet 110.02 espaçados de 0,50 m e posicionados a 0,50 m de altura dos vasos. Avaliou-se a intoxicação das plantas com uma escala visual de notas e, no final dos estudos, a altura e massa da matéria seca de plantas. Para o P. maximum cv. Mombaça, apenas os herbicidas imazaquin, na menor dose, imazethapyr e flumetsulam aplicados em pré-emergência, foram seletivos; os herbicidas metsulfuron-methyl, chlorimuron-ethyl, nicosulfuron, diclofop-methil, atrazine e ametryne aplicados em pós-emergência, foram visualmente seletivos para a cultivar Mombaça. Para o P. maximum cv. Tanzânia, os herbicidas... . / This research was accomplished in eight experiments, carried out in green house with the aim of to avaluating the selectivity of different herbicides, applied at pre and post-emergence, in the following tropical grass forages: Brachiaria decumbens Stapf cv. Basilisk, Brachiaria brizantha (Hochst) Stapf cv. Marandu, Panicum maximum Jacq cv. Tanzânia and Panicum maximum Jacq cv. Mombaça. The herbicides and doses (g a.e. /ha) acessed were (i) pulverized in post-emergence imazethapyr at 50 and 100, metsulfuron-methyl at 1,0 and 2,0, chlorimuron-ethyl at 7,5 and 15, nicosulfuron at 25 and 50, bentazon at 360 and 720, diclofop-metil at 140 and 280, fenoxaprop-ethyl at 30 and 60, atrazine at 1.500 and 3.000 and ametryne at 625 and 1.250, (ii) in pre-emegency, alachlor at 1.680 and 3.360, metolachlor at 1.200 and 2.400, diuron at 800 and 1.600, imazaquin at 75 and 150, imazapyr at 250 and 500, imazethapyr at 50 and 100, clomazone at 450 and 900, flumetsulam at 70 and 140, ametryne at 625 and 1.250, metribuzin at 525 and 1.050, trifluralin at 900 and 1.800, and a control plot. The experimental design was totally randomized, with the trataments with six replications. The application solution consumed was 180 L/ha and the application bar had four TEEJET 110.02 plain jet nozzle, at 0,5 m height from each other and at 0,5 m from the pulverized pots. The plants intoxication was evaluated by a visual grade scale. At the end of the study plant height and dry matter weight were evaluated. To P. maximum cv. Mombaça, only imazaquin at the lower dose, imazethapyr and flumetsulam applied in preemergency acted selectively. The post-emergence herbicides, metsulfuron-methyl, chlorimuron-ethyl, nicosulfuron, diclofop-methil, atrazine and ametryne were visually selectives to Mombaça cultivar. To P. maximum cv. Tanzânia, the post-emergence herbicides... (Complete abstract, click electronic address below).

The objectives of this study were to assess the effects of prescribed burning on herbaceous and browse forage quality in the aspen forest type for elk and domestic sheep. Plant samples of selected forage species were taken from burned and nonburned plots within three different prescribed burns in southeastern Idaho. These samples were analyzed for in vitro dry matter digestibility, crude protein, calcium and phosphorus. Data were analyzed using the analysis of variance. There was little improvement in forage quality as a result of prescribed burning, with some reduction in quality in 1983 exhibited by pinegrass (Calamagrostis rubescens). Aspen on August 2 , 1982 had improved elk IVDMD and Ca/P ratios, crude protein and phosphorus levels and decreased calcium content on the burned versus the nonburned areas . By August 22, 1982, only crude protein levels were improved. All of the shrubs analyzed for that date had improved crude protein levels on the burned versus the nonburned areas, but only serviceberry had higher phosphorus levels. In 1983, none of the shrubs or forbs had improved forage quality. Pinegrass decreased in IVDMD and c rude protein on the burned areas, possibly due to a more rapid maturation and increased seed production. Other benefits from prescribed burning included a changing species composition from dense shrub matts to more palatable and nutritious forbs that are not found on unburned areas . This reduction in shrubs also led to greater access of animals to available forage. The aspen type was shown to have a nutritious and valuable understory, irrespective of prescribed burning.

"Pasture is the natural food of all domesticated herbivore, especially the ruminant, and the only single feed upon which it can be maintained in health indefinitely."

Farmers in the developing world frequently find themselves in uncertain and risky environments: often having to make decisions based on very little information. Functional models are needed to support farmers tactical decisions. In order to develop an appropriate model, a comparison is carried out of potential modelling approaches to address the question of what to grow where. A probabilistic GlS model is identified in this research as a suitable model for this purpose. This model is implemented as the stand-alone Spatial Decision Support System (SDSS) CaNaSTA, based on trial data and expert knowledge available for Central America and forage crops. The processes and methods used address many of the problems encountered with other agricultural DSS and SDSS. CaNaSTA shows significant overlap with recommendations from other sources. In addition, CaNaSTA provides details on the likely adaptation distribution of each species at each location, as well as measures of sensitivity and certainty. The combination of data and expert knowledge in a spatial environment allows spatial and aspatial uncertainty to be explicitly modelled. This is an original approach to the problem of helping farmers decide what to plant where.

The effects of late spring defoliation on the winter forage quality of bluebunch wheatgrass (Agropyron spicatum [Pursh] Scribn. & Smith), Idaho fescue (Festuca idahoensis Elmer) and elk sedge (Carex geyeri Boott) and the response of wintering Rocky Mountain elk (Cervus elaphus nelsoni Bailey) to changes in winter range forage quality were examined. The study included two experiments; a hand clipping experiment conducted on bluebunch wheatgrass and a sheep grazing experiment conducted on bluebunch wheatgrass, Idaho fescue, and elk sedge. Four treatments were applied to bluebunch wheatgrass in the clipping experiment: 1) the entire basal area of individual plants was clipped to a 7.6 cm stubble height during the mid boot phenological stage, 2) one-half the basal area of individual plants was clipped to a 7.6 cm stubble height during the mid boot stage, 3) the entire basal area of individual plants was clipped to a 7.6 cm stubble height during the inflorescence emergence stage, and 4) plants were left unclipped as a control. In early November, forage samples from each of the three clipping treatments exhibited increases in percent crude protein and percent in vitro dry matter digestibility compared to the unclipped control treatment. Clipping the entire basal area of bluebunch wheatgrass plants to a 7.6 cm stubble height during the mid boot or inflorescence emergence stage was more detrimental to plant vigor than clipping one-half the plant basal area during the mid boot stage or leaving the plants unclipped. There was some evidence that clipping one-half the plant basal area during the mid boot stage may improve plant vigor compared to no clipping. Differences in crude protein, in vitro dry matter digestibility, and dry matter yield from winter forage samples of bluebunch wheatgrass, Idaho fescue and elk sedge were detected between plots grazed by domestic sheep during the boot stage of bluebunch wheatgrass and plots where sheep grazing was excluded. No differences in winter elk utilization of bluebunch wheatgrass, Idaho fescue, or elk sedge were detected between the late spring sheep grazing treatment and sheep exclusion treatment. Plot occupancy by wintering elk was similar between plots grazed by sheep and plots where sheep grazing was excluded. Although, wintering elk did not appear to respond to the livestock grazing treatment, results from this study suggest small improvements in the winter forage quality of perennial grasses such as bluebunch wheatgrass can result following late spring defoliation. Forage conditioning treatments which produce even small improvements in forage quality may be important to the nutritional status of wintering elk. / Graduation date: 1997

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2001. / Includes bibliographical references.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb. 12, 2010 ). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Dr. Robert L. Kallenbach, Thesis Supervisor. Includes bibliographical references.

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