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Part I Four-week old tomato (Lycopersicon esculentum Mill.) seedlings were exposed to different constant temperatures of 15, 25, 35, or 45 c. To determine the effect of temperature on Abscisic Acid (ABA) young and old leaves were harvested at 0, 6, 12, 24, or 48 hand free, hydrolyzable and total ABA were measured using gas liquid chromatographic methods. Temperature had a significant effect on free , hydrolyzable and total ABA in both young and old leaves. Time had a significant effect as a cubic function on all ABA measurements in old leaves but in young leaves a significant effect was observed only on the hydrolyzable ABA. Interactions between temperature and time were observed in both young and old leaves. Young leaves had significantly higher amounts of free and hydrolyzable ABA than did old leaves . The total ABA levels were not significantly different in young and old leaves . Suboptimal temperatures increased ABA levels in the plants, in a manner similar to that of other kinds of stresses. Part II Five- week old tomato plants (Lycopersicon esculentum Mill.) were exposed to day-night temperatures of 10-5, 15-10, 25 - 15, 35-25, or 45-35 C. The day length was 16 h with a light intensity of approximately 400 ~ E m- 2s-1 . Plant tops were sampled at 12, 24 , 48, 68, or 72 h. Free, hydrolyzable and total absciscis acid (ABA) quantities were measured using standard gas chromatographic techniques. Stressful temperatures significantly increased both free and hydrolyzable ABA levels . The highest ABA levels were observed in plants grown at 10-5 C. Although time significantly affected ABA levels, its role needs more precise definition . Due to the similar involvements of ABA in temperature-induced and other stresses, ABA may be hypothesized to be a common mediator for different stresses. Part III Warm season crops: bean (Phaseolus vulgaris) CV . Burpee Stringless Green Pod; corn (Zea mays) CV. Golden ,Jubilee; Cantaloupe (Cucumis melo) cv. Hales Best; eggplant (Solunum melongena) CV. Ichiban; and okra (Hibiscus esculentus) CV . Dwarf Green and cool season crops: beet (Beta vulgari s) CV. Early wonder; lettuce (Lactuca sativa) •CV. Great Lakes; cabbage (Brassica oleracea) cv. Savoy; radish (Raphanus sativus) CV. Scarlet Globe; and pea (Pisum sativum) cv. Little Marvel were exposed to 10, 25 , or 40 C. After 24 h free and hydrolyzable ABA and DPA were measured in the plant tops using standard gas chromatographic methods. Warm season crops exhibited elevated levels of PABA, HABA and DPA under 10 C, compared to those at 25 or 40 c. Cool season crops showed similar PABA , HABA and DPA contents under all temperatures, except pea which had higher PABA and HABA levels at 40 C and beet which showed lower levels of HABA at 25 C as compared to 10 and 40 C. DPA existed at much higher concentrations than ABA in all plants of the two groups. It is concluded that while 1 0 C is stressful to warm season crops and thus the ABA and DPA increases, it is not so favorable to cool season crops. A temperature of 40 C would be stressful to both groups, but as long as water supply to the plant is not limiting the plants would not actively produce ABA . Higher levels of DPA under stressful conditions would warrant consideration and taking into account the role of metabolism in regulation of total ABA in the plant.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2002. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.)--University of Western Australia, 2007.

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains ix, 80 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 65-80).

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains viii, 140 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 119-140).

Memorial apresentado ao Instituto de Biociências, Universidade Estadual Paulista "Júlio de Mesquita Filho", como parte dos requisitos para obtenção do título de Professor Livre-Docente na Dosciplina de Fisiologia Vegetal / Resumo: As sementes de anonáceas são conhecidas por apresentarem mecanismos de dormência, o que dificulta a perpetuação das espécies e a formação de áreas produtivas para a exploração comercial. Deste modo, os objetivos deste trabalho foram estudar curva de aquisição de água; a germinação de sementes tratadas com GA3 e GA4+7 + Benziladenina; o balanço hormonal e a degradação de reservas em sementes de Annona diversifolia Saff e Annona purpurea Moc & Sessé ex Dunal tratadas com reguladores vegetais para a superação da dormência. Para tanto foram realizados três experimentos. Para a construção da curva de aquisição de água foram utilizadas 4 repetições de 25 sementes que foram mantidas em embebição e pesadas durante 480 horas. O segundo experimento foi constituído pela germinação das sementes tratadas com os reguladores vegetais; o delineamento experimental empregado foi o inteiramente casualizado com 4 repetições de 25 sementes por parcela em esquema fatorial 2 x 7 (reguladores x concentrações). Os tratamentos foram constituídos pelas combinações entre concentrações de GA3 e de GA4+7 + Benziladenina (GA4+7 + BA) x 0, 200, 400, 500, 600, 800 e 1000 mg L-1 i.a.. No terceiro experimento foram quantificados ABA (Ácido abscísico) e GA (Giberelinas), proteínas, açúcares... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Annonaceae seeds have been known by presenting dormancy mechanisms, which makes difficult the perpetuation of species and the formation of roductive areas for commercial exploration. Thus, the present work aimed to evaluate water uptake curve; germination of seeds treated with GA3 and GA4+7 + Benzyl adenine; hormone balance and reserve degradation in Annona diversifolia Saff and Annona purpurea Moc & Sessé ex Dunal seeds subjected to plant growth regulators for dormancy break. Three experiments were carried out. To obtain the water uptake curve, four replicates of 25 seeds were kept in imbibition and weighed for 480h. The second experiment evaluated the germination of seeds treated with plant growth regulators; experimental design was completely randomized, with four replicates of 25 seeds per plot in the 2x7 (plant growth regulators x concentrations) factorial arrangement. Treatments consisted of combinations between concentrations of GA3 and GA4+7 + Benzyl adenine (GA4+7 + BA) with 0, 200, 400, 500, 600, 800 and 1000 mg L-1 a.i.. In the third experiment, ABA (abscisic acid), GA (gibberellins), proteins, total soluble sugars and lipids were quantified in seeds soaked in water, without imbibition and soaked in GA4+7 + BA for 15 days (on the 0th, 2nd, 5th, 10th and 15th days). Based... (Complete abstract click electronic access below)

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Seed development, germination and dormancy, considered as the most important phenomena in seeds, are regulated by several plant hormones; gibberellin (GA) and abscisic acid (ABA) being the major players acting antagonistically. The regulation of these seed related processes by GA and ABA is dependent partly on the endogenous levels of the two hormones, which in turn are determined by the balance between their biosynthesis and catabolism. This thesis investigated the spatial and temporal expression patterns of several members of the GA and ABA biosynthetic and catabolic gene families during grain development using a non-dormant cultivar and during imbibition using grains collected from dormant and non-dormant cultivars of barley. In addition, the thesis examined the effect of exogenous ABA treatment, and after-ripening of seeds collected from dormant cultivars on the expression patterns GA and ABA metabolism genes during grain development and imbibition, respectively. The results suggest that specific members of the gene families related to the metabolic pathways of the two hormones exhibit distinct spatial and temporal roles in the regulation of barley grain development, dormancy and germination. / October 2015