Experiments were performed to assess regulatory factors governing maize embryo maturation and vivipary. Both visual and molecular markers of embryo development were used to examine the roles of the hormones abscisic acid (ABA) and gibberellins (GAs), as well as water stress in governing transit from early embryogeny to maturation-phase development. A differential screen identified cDNAs whose expression is impaired in maize viviparous mutants which fail to undergo maturation and instead precociously germinate. The cDNAs isolated in this screen absolutely required both ABA and the Viviparousl (Vpl) gene product for expression both in vivo and in vitro. Two novel clones were isolated: a maize homologue of the wheat metallothionein gene E[subscript]c and a second clone which may encode a novel seed storage protein of maize. In a separate screen, a maize cDNA encoding a Lea group 3 protein was isolated. Like many maturation-associated genes, maize Lea 3 was shown to ABA-inducible but is also expressed in response to water stress in the absence of ABA or the Vp 1 gene. We examined whether gibberellins might also be a factor modulating precocious germination. Gibberellin inhibitors applied to cultured wildtype embryos suppressed precocious germination and enhanced anthocyanin accumulation in a developmentally specific manner. These behaviors mimicked the effect of ABA and they were reversed by the addition of exogenous GA���. Vivipary in vivo resulting from diminished ABA levels could be suppressed by either chemical or genetic reduction of GA levels in immature kernels and resulted in desiccation-tolerant seed. In contrast, reduction of endogenous gibberellins did not suppress vivipary of the ABA-insensitive mutant vp1. Temporal analysis of gibberellin accumulation in developing kernels revealed the accumulation of two bioactive species (GA��� and GA���) during a developmental window just prior to peak ABA levels. It is suggested that these species stimulate a developmental program leading to vivipary in the absence of sufficient levels of ABA and that reduction of GA levels reestablishes a hormone balance appropriate for suppression of germination and induction of maturation in ABA-deficient kernels. The failure to suppress vivipary via reduction of GA levels in the ABA-insensitive mutant vp1 suggests that the wildtype gene product functions downstream of the sites of GA and ABA action in regulation of maturation versus germination. / Graduation date: 1995

D8 originally designated as the dominant stature mutant of maize, was characterized and shown to be incompletely dominant. The study included morphological measurements, cytology, hormone studies, and enzyme and protein analysis. The effect of the D8 mutation can be detected after 40 hours of germination of the coleoptile. Dwarf (D8/d8) seedling length is 1/2 of the normal sib length for coleoptile, first leaf, and mesocotyl. The cell measurements indicate that cell elongation and cell division are involved in the size discrepancy. Mature dwarf plants have shorter internodes and the shorter, wider leaves are a darker green than the normal plant. The homozygous D8/D8 displays normal meiotic division and pollen formation is normal upto the 2 nucleate stage. Pollen viability of the homozygote is low and no seed was obtained in crosses involving this genotype. Several biological stains were used to test pollen viability with the results indicating greater than 85% viability for the heterozygote and less than 15.6% viability for the homozygote. The examination of the pachytene chromosomes of heterozygotes indicates a loop on a large chromosome. This loop is only found in the D8 heterozygote and implies a duplication or deficiency may be involved with the D8 phenotype. Avena straight growth bioassay for auxin displayed no significant difference in auxin production between dwarf and normal coleoptile tips. The D8 dwarf seedlings responded to the exogenous application of auxin, kinetin, and casamino acids in the same pattern as the normal seedlings, but never attained normal stature. Gibberellic acid (GA) and cyclic adenosine monophosphate (cAMP) exogenous applications displayed a difference in dwarf and normal response patterns and implies that the utilization or destruction of these substances may be involved. The investigation of Laemmli gel patterns for the three genotypes failed to show a difference. The soluble proteins formed 27 bands from the coleoptiles of each phenotype. Adh-1 gel patterns and pollen staining was utilized to examine the possibility of a deletion overlapping this locus. The Adh-1 locus has been mapped proximal to the D8 locus. The results indicate the Adh locus is not included in the putative D8 deletion.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1982. / Bibliography: leaves 226-229. / Microfiche. / xxiv, 229 leaves, bound ill. 29 cm

Refined corn hulls (bran) were hydrolyzed with 30 mM oxalic acid in order to release carbohydrate fragments containing ferulic acid. The fragments which were high in ferulic acid also contained high levels of arabinose, xylose, and galactose, which are characteristic of sugars comprising corn hull hemicellulose side chains. Corn hull hydrolysate fragments were fractionated by chromatography to obtain purified feruloyl oligosaccharides. A The structure of the major feruloyl compounds were characterized by analysis of the products of acid, alkali, and enzyme hydrolysis, in combination with carbon-13 and 2D proton NMR spectroscopy. Three feruloyl oligosaccharides were identified as 5-0-(trans)-feruloyl-L-arabinofuranose (FA), 2-0-β-xylopyranosyl-(5-0-trans-feruloyl arabinofuranose) (FXA), and 0-(6-0-trans-feruloyl-α-D-galactopyranosyl)-(1-4) -O-β-D-xylopyranosyl-(1-2)-L-arabinofuranose (FGXA). / Ph. D.

Made available in DSpace on 2014-06-11T19:30:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-04-16Bitstream added on 2014-06-13T19:19:14Z : No. of bitstreams: 1 pinotti_eb_dr_botfca.pdf: 1407928 bytes, checksum: c9c2f72808b8752be5004930cfd9e18a (MD5) / As constantes modificações de ordem morfofisiológica que tem ocorrido nas cultivares de milho obrigam a uma permanente reavaliação de posicionamento quanto aos aspectos fitotécnicos associados, principalmente a época de semeadura e distribuição espacial das plantas de milho. A hipótese de que cultivares com exigência de somatório térmico distintos respondem de maneira diversa em suas características morfológicas e fisiológicas quando semeados em épocas, com conseqüência sobre a produtividade foi considerado no presente trabalho. Portanto o objetivo deste trabalho foi de verificar alterações morfologias e fisiológicas de dois cultivares de milho, com somatórias térmicas distintas, semeadas em quatro populações de plantas, 30.000, 45.000, 60.000 e 75.000 pl ha-1 e três épocas de semeadura, janeiro, fevereiro e março, dentro do período da safrinha. O experimento foi conduzido em área de Argissolo Vermelho Amarelo Distrófico, arênico, situado na Fazenda do Engenho, no município de Pompeia (SP), na época da safrinha de 2010. O delineamento experimental utilizado foi o de blocos casualizados, em esquema fatorial 2 x 4 x 3, com quatro repetições, em parcelas de sete linhas espaçadas de 0,45m, com 12m de comprimento. Foram avaliadas as características morfológicas e agronômicas estandes inicial e final, altura de plantas, número de folhas, altura de inserção de espiga, relação entre altura de espiga e altura de planta, diâmetro de colmo, área foliar por planta, índice de área foliar, índice de persistência e senescência foliar, grau Brix no florescimento masculino e maturidade fisiológica, porcentagem de plantas acamadas e quebradas. Foram também avaliadas as características de espiga e os componentes de produção, comprimento da espiga, número de fileiras de grãos por espiga, diâmetros da espiga e... / The constant morphophysiological changes that have occured in maize cultivars requires na ongoing reassessment of the issues associated to crop management specially seeding time and spatial distribution of maize plants. The hypothesis that cultivars with different thermal requirements respond in different times, with consequences to their productivity was considered in this work. Therefore the objective of this essay was to verify morfhological and physiological changes of two maize cultivars with different thermal sums, seeded in four different plant populations, 30,000; 45,000; 60,000 and 75,000 pl ha-1 and three seeding dates, january, february and march, within the period of the second crop. The experiment was conducted in na area located at Farm of Engenho in Pompeia – SP, Brazil, during the second crop season of 2010. The experimental design was a randomized block design in a factorial scheme of 2 X 4 X 3 with four replications in plots of seven rows spaced 0,45m and 12 m long. It was evaluated the morphological and agronomic characteristics and initial and final plant populations, plant height, number of leaves, height of insertion of ear, relationship between ear insertion height and plant height, stem diameter, leaf área per plant, leaf área índex, persistence índex and leaf senescence, Brix rate at male flowering and physiological maturity, percentage of plants broken and stalk loged plants. As well the evaluated the characteristics of ear and yield components, eat length, number of kernel rows per ear, ear diameter and cob, grain length, weight of thousand grains, grain weight per ear, number of grains per ear, number of ears per hectare, ear index and productivity. The parameters evaluated were influenced by hibrids, except leaf area in male flowering, leaf area at physiological maturity, grain length, thousand grain weight... (Complete abstract click electronic access below)

Orientador: Sílvio José Bicudo / Banca: Claudio Cavariani / Banca: Elizeu Luiz Brachtvogel / Banca: Dirceu Maximino Fernandes / Banca: Simério Carlos Silva Cruz / Resumo: As constantes modificações de ordem morfofisiológica que tem ocorrido nas cultivares de milho obrigam a uma permanente reavaliação de posicionamento quanto aos aspectos fitotécnicos associados, principalmente a época de semeadura e distribuição espacial das plantas de milho. A hipótese de que cultivares com exigência de somatório térmico distintos respondem de maneira diversa em suas características morfológicas e fisiológicas quando semeados em épocas, com conseqüência sobre a produtividade foi considerado no presente trabalho. Portanto o objetivo deste trabalho foi de verificar alterações morfologias e fisiológicas de dois cultivares de milho, com somatórias térmicas distintas, semeadas em quatro populações de plantas, 30.000, 45.000, 60.000 e 75.000 pl ha-1 e três épocas de semeadura, janeiro, fevereiro e março, dentro do período da safrinha. O experimento foi conduzido em área de Argissolo Vermelho Amarelo Distrófico, arênico, situado na Fazenda do Engenho, no município de Pompeia (SP), na época da safrinha de 2010. O delineamento experimental utilizado foi o de blocos casualizados, em esquema fatorial 2 x 4 x 3, com quatro repetições, em parcelas de sete linhas espaçadas de 0,45m, com 12m de comprimento. Foram avaliadas as características morfológicas e agronômicas estandes inicial e final, altura de plantas, número de folhas, altura de inserção de espiga, relação entre altura de espiga e altura de planta, diâmetro de colmo, área foliar por planta, índice de área foliar, índice de persistência e senescência foliar, grau Brix no florescimento masculino e maturidade fisiológica, porcentagem de plantas acamadas e quebradas. Foram também avaliadas as características de espiga e os componentes de produção, comprimento da espiga, número de fileiras de grãos por espiga, diâmetros da espiga e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The constant morphophysiological changes that have occured in maize cultivars requires na ongoing reassessment of the issues associated to crop management specially seeding time and spatial distribution of maize plants. The hypothesis that cultivars with different thermal requirements respond in different times, with consequences to their productivity was considered in this work. Therefore the objective of this essay was to verify morfhological and physiological changes of two maize cultivars with different thermal sums, seeded in four different plant populations, 30,000; 45,000; 60,000 and 75,000 pl ha-1 and three seeding dates, january, february and march, within the period of the second crop. The experiment was conducted in na area located at Farm of Engenho in Pompeia - SP, Brazil, during the second crop season of 2010. The experimental design was a randomized block design in a factorial scheme of 2 X 4 X 3 with four replications in plots of seven rows spaced 0,45m and 12 m long. It was evaluated the morphological and agronomic characteristics and initial and final plant populations, plant height, number of leaves, height of insertion of ear, relationship between ear insertion height and plant height, stem diameter, leaf área per plant, leaf área índex, persistence índex and leaf senescence, Brix rate at male flowering and physiological maturity, percentage of plants broken and stalk loged plants. As well the evaluated the characteristics of ear and yield components, eat length, number of kernel rows per ear, ear diameter and cob, grain length, weight of thousand grains, grain weight per ear, number of grains per ear, number of ears per hectare, ear index and productivity. The parameters evaluated were influenced by hibrids, except leaf area in male flowering, leaf area at physiological maturity, grain length, thousand grain weight... (Complete abstract click electronic access below) / Doutor

Copper and Zn deficiencies of crop plants occur in various areas throughout the world. The sulfate forms of Cu and Zn are generally used to correct these micronutrient deficiencies. In agricultural practices, Cu and Zn are applied to soils not only as a fertilizer but also as manures, pesticides and waste materials such as sewage sludge. High levels of Cu and Zn application to agricultural soils are considered to pose a potential hazard to plants and animals. Research findings have not established Cu and Zn levels that either injure plants or increase Cu and Zn concentrations in edible plant portions to undesirably high levels. Published data on the fate of applied Cu and Zn indicate that there is little, if any, downward movement of these micronutrients in soils and that, with time, applied Cu and Zn revert to plant unavailable forms in soils. / Master of Science