Na subfamília Bromelioideae o chamado Complexo Nidularioide apresenta gêneros intimamente relacionados que apresentam historicamente problemática circunscrição genérica. A busca por caracteres morfológicos, em especial os caracteres reprodutivos tem auxiliado a compreensão de processos evolutivos em diferentes grupos. Esse trabalho buscou descrever a estrutura anatômica do ovário e do rudimento seminal nas espécies do Complexo Nidularioide: Canistropsis billbergioides, Canistrum aurantiacum, Edmundoa lindenii, Neoregelia johannis, Nidularium innocentii e Wittrockia superba. Ovários dessas espécies em diferentes estádios do desenvolvimento foram coletados e fixados em glutaraldeído 1% e formaldeído 4%, lavados em tampão fosfato de sódio 0,1 M, pH 7,2, desidratados em série etílica (10- 100%), e incluídos em hidroxietilmetacrilato. Cortes de 4 μm de espessura foram montados em lâmina e corados com azul de toluídina O. Em todas as espécies analisadas foi observada a formação de aerênquima tipo esquizógeno no mesofilo ovariano. As espécies C. billbergioides, E. lindenii var. rosea, N. johannis, N. innocentii e Wittrockia superba apresentaram grande número de caracteres compartilhados, como a presença de três camadas de células no tegumento externo, epiderme nucelar e estrato parietal compostos por uma ou duas camadas de células. A espécie E. lindenii var. rosea apresentou tricomas epidérmicos na superfície do ovário, sendo esses tricomas descritos como uma nova morfologia de tricomas para a família Bromeliaceae. Considerando os caracteres observados, a espécie C. aurantiacum apresentou menor número de caracteres compartilhados com as demais espécies do Complexo Nidularioide. / In Bromelioideae subfamily, the so-called Nidularioid Complex presents intimately related genera, bearing historical generic circumscription issues. The search of morphological features, concerning mainly reproductive characters, has helped to enlighten evolution processes between different groups within the family. This work aimed to describe the ovary and ovule anatomical structure of the Nidularioid Complex species: Canistropsis billbergioides, Canistrum aurantiacum, Edmundoa lindenii var. rosea, Neoregelia johannis, Nidularium innocentii and Wittrockia superba. Ovaries in different development stages were collected and fixed in a 1% glutaraldehyde and 4% formaldehyde solution, washed in a sodium phosphate 0.1 M and 7.2 pH solution, and subsequently dehydrated in a crescent ethylic series, ranging from 10% to 100%; lately, the specimens were included in hydroxyethylmethacrylate. 4 μm cuts were mounted in glass blades, and stained with toluidine blue O. In all analyzed species a schizogenous type aerenchyma could be observed within the ovarian mesophyll. C. billbergioides, E. lindenii, N. johannis, N. innocentii and Wittrockia superba presented a great amount of common characters, such as a three layer cell in the outer tegument, nucellar epidermis and parietal tissue composed of two or more cell layers. E. lindenii var. rosea presented epidermic trichomes in the ovary surface, being these trichome described as a new kind of trichome morphology for the Bromeliaceae family. C. aurantiacum presented a minor quantity of common characters with the other analyzed species of the Nidularioid Complex.

This study examines the role of deffensive host-plant traits in structuring the community of leaf-chewing insects living on willows. Host-plant phylogeny was reconstructed and leaf morphology and content of three different groups of secondary metabolites were measured. Relationships between defensive leaf traits were examined and their influence on insect community structure was analyzed.

Submitted by THAIS LOHAINE BRAGA DOS SANTOS (thais_lohaine@hotmail.com) on 2018-07-06T16:45:21Z No. of bitstreams: 1 SANTOS, TLB 2018.pdf: 3611620 bytes, checksum: 7a88d959d68f69391e2f3c1e5564fc2f (MD5) / Approved for entry into archive by Ana Lucia de Grava Kempinas (algkempinas@fca.unesp.br) on 2018-07-10T12:27:20Z (GMT) No. of bitstreams: 1 santos_tlb_me_bot.pdf: 3611620 bytes, checksum: 7a88d959d68f69391e2f3c1e5564fc2f (MD5) / Made available in DSpace on 2018-07-10T12:27:21Z (GMT). No. of bitstreams: 1 santos_tlb_me_bot.pdf: 3611620 bytes, checksum: 7a88d959d68f69391e2f3c1e5564fc2f (MD5) Previous issue date: 2018-04-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O feijão-comum (Phaseolus vulgaris L., Fabaceae) apresenta elevado potencial prodtivo e é um dos alimentos mais consumidos em todo o mundo. Dentre os fatores que ocasionam queda de produtividade na cultura do feijoeiro, destaca-se o ataque de insetos-praga como a mosca-branca, Bemisia tabaci (Gennadius) biótipo B (Hemiptera: Aleyrodidae), em função dos intensos danos diretos e indiretos que podem ocasionar as plantas dessa leguminosa. Seu controle é realizado principalmente por meio de aplicações de inseticidas sintéticos, muitas vezes utilizadas em doses acima das recomendadas, favorecendo a seleção de insetos resistentes. O uso de genótipos resistentes pode ser uma estratégia eficiente para o manejo integrado da mosca-branca nas lavouras. Assim, este trabalho avaliou a possível expressão de antixenose e antibiose a partir de 78 genótipos de feijoeiro. Análises físicas e morfológicas das folhas também foram realizadas, a fim de identificar possíveis fatores de resistência dos genótipos a B. tabaci biótipo B. Inicialmente, realizaram-se ensaios com e sem chance de escolha (antixenose), onde avaliou-se o número de adultos, ovos e a colonização por ninfas nos genótipos de feijão. Análises colorimétricas e a caracterização (tipificação e densidade) dos tricomas existentes foram realizadas a fim de se estabelecer possíveis correlações com a colonização do inseto nesta etapa. Posteriormente, avaliou-se o desempenho biológico do inseto confinado a 17 genótipos previamente selecionados (Capítulo 1), a fim de caracterizar a expressão de antibiose. Para tanto, foram avaliados os seguintes parâmetros biológicos: período de incubação, período de duração dos instares, período ninfal total, período de desenvolvimento de ovo a adulto, mortalidade por ínstar ninfal e viabilidade ninfal. No teste de anixenose com chance de escolha, os genótipos BRS Ametista, BRS Estilo, BRS Esplendor, SCS 204 Predileto, BRS Notável, IPR Eldorado, CHIB 06, IPR Quero-Quero, Iapar 81, CHIP 338, IPR Garça, Arcelina 4, SCS 202 Guará, IAC Esperança, H96102-1-1-1-52, CHIP 348, Carioca Comum, CHIP 300, IAC Carioca Eté, IAC Ybaté e Tybatã apresentaram menor oviposição e colonização por ninfas da mosca-branca. Em teste sem chance de escolha, a maioria dos genótipos revelou baixa colonização por adultos da mosca-branca, com destaque para CHIB 06, IPR Garça, CHIP 300 e IAC Esperança. Verificou-se que os genótipos em que se constatou o maior número de adultos no ensaio sem chance de escolha apresentaram alta intensidade de luminosidade (L*), verde (a*) e amarelo (b*), indicando correlação positiva desses fatores com a atratividade e oviposição da mosca-branca. Nos genótipos BRS Ametista, SCS 204 Predileto, BRS-Estilo, IPR Eldorado, SCS-202 Guará, Carioca Comum, Arcelina 4, CHIP 348 e IAC Esperança a resistência se mostrou mais estável, manifestando-se também, em elevados níveis (≤ 20 adultos por folíolo e ≤ 1 ovo/cm2) no ensaio sem chance de escolha. No ensaio de antibiose, o genótipo CHIP 300 ocasionou um prolongamento acentuado no período de ovo a adulto (~ 10 dias), enquanto que os genótipos BRS Estilo, Arcelina 4, IPR Garça, Tybatã, CHIP 300, IPR Eldorado, H96A102-1-1-1-52 e CHIB 06 afetaram negativamente a viabilidade e mortalidade das ninfas da mosca-branca, sugerindo elevados níveis de resistência por antibiose e/ou antixenose. Esses genótipos constituem potenciais fontes de resistência a B. tabaci biótipo B e podem ser explorados em programas de melhoramento genético que visam a obtenção de linhagens resistentes a insetos. / The common bean, Phaseolus vulgaris L., (Fabaceae) has a high yield potential and is one of the most consumed food in the world. Among the factors that negative affects the common bean yield, the occurence of silverleaf whitefly Bemisia tabaci Gennadius, 1889 biotype B (Hemiptera: Aleyrodidae) has been highilghted due its direct and indirect damage. B. tabaci are almost exclusively managed by insecticide sprays where the over-application and indiscriminate use of pesticides has had several adverse consequences like insecticide resistance development. Host-plant resistance may be a valuable strategy for the integrated management of B. tabaci. Therefore, this work aimed to evaluate the effect of 80 bean genotypes to this insect to verify the occurence of antixenosis and antibiosis. Initially, multiple-choice trials were carried out, in order to evaluate the oviposition and the nymphs colonization preference. Morphological caracteristics of leaf trichomes (size and density) and colorimetric analyses were performad to establish possible correlations between genotypes and insect colonization. Subsequently, 17 bean genotypes were selected and a no-choice test was conducted to verify the occurrence of antibiosis (Charpter 1). Therefore, we evaluated the incubation period of eggs, nymphal period, complete development period (egg-adult) and viability of the silverleaf whitefly nymphs. From the results of the multiple-choice trial, genotypes BRS Ametista, BRS Estilo, BRS Esplendor, SCS 204 Predileto, BRS Notável, IPR Eldorado, CHIB 06, IPR QueroQuero, IAPAR 81, CHIP 338, IPR Garça, Arcelina 4, SCS 202 Guará, IAC Esperança, H96102-1-1-1-52, CHIP 348, Carioca Comum, CHIP 300, IAC Carioca Eté, IAC Ybaté e Tybatã were the least used for oviposition and nymphs colonization. In the no-choice test, most genotypes were less attractive to B. tabaci and genotypes CHIB 06, IPR Garça, CHIP 300 e IAC Esperança had less oviposition. The most attractive genotypes presented high luminosity (L*) and more intense green (a *) and yellow (b*) colors indicating positive. Besides that, genotypes BRS Ametista, SCS 204 Predileto, BRS Estilo, IPR Eldorado, SCS-202 Guará, Carioca Comum, Arcelina 4, CHIP 348 and IAC Esperança showed the highest resistance stability and hight resistance level was observed in the no-choice test (≤ 20 adults/leaflet and ≤ 20 eggs/cm2 ). The genotype CHIP 300 prolonged the developmental period from egg to adult (~ 10 d) and BRS Estilo, Arcelina 4, IPR Garça, Tybatã, CHIP 300, IPR Eldorado, H96A102-1-1-1-52 and CHIB 06 caused nymphal mortality suggesting high levels of antibiosis and antixenosis. Thus, this genotypes are promising for use in breeding programs to develop resistance to whitefly aimed its implementation on integrated management of B. tabaci in common bean crops.

Orientador: Silvia Rodrigues Machado / Banca: Elza Maria Guimarães dos Santos / Banca: Adriana Hissae Hayashi / Resumo: Uma característica da família Verbenaceae é a presença de tricomas secretores, geralmente produtores de óleos essenciais de grande valor medicinal. Muitas espécies de Lippia Houst. são utilizadas em programas fitoterápicos e de complementação alimentar no Brasil, sendo L. alba e L. sidoides as mais utilizadas e estudadas. O cerrado possui aproximadamente 33 espécies de Lippia cujo potencial farmacológico é desconhecido. Apesar da importância econômica como fonte de medicamentos e da representatividade de Lippia na flora aromática nativa, pouco se conhece sobre os aspectos estruturais e da secreção dos seus tricomas secretores. Neste trabalho foram estudados os tricomas secretores presentes em órgãos vegetativos e reprodutivos de L. stachyoides Cham. sob o ponto de vista morfológico, ontogenético, histoquímico e ultra-estrutural. Foram utilizadas técnicas convencionais em estudos anatômicos e ultra-estruturais; a identificação in situ da composição química das substâncias presentes nos tricomas foi realizada por meio de testes histoquímicos. Em L. stachyoides, os tricomas secretores são capitados e foram classificados em cinco tipos morfológicos, os quais são amplamente distribuídos no caule, folhas e inflorescências. A histoquímica revelou que nos tipos I e IV predominam substâncias hidrofílicas e nos tipos II e V, substâncias lipofílicas. De um modo geral, as características ultraestruturais observadas em cada tipo de tricoma corroboraram os resultados das análises histoquímicas. Os resultados do presente trabalho sugerem que as variações morfológicas dos tricomas secretores em L. stachyoides estão associadas com a composição química da secreção / Abstract: A feature of the family Verbenaceae is the presence of secretory trichomes, producers of essential oils with great medicinal value. Many species of Lippia Houst. are employed in phytotherapic and food complementation programs in Brazil, being L. alba and L. sidoides the most employed and studied species. The Brazilian cerrado has approximately 33 species of Lippia, whose pharmacological potential is unknown. Despite the economic importance of Lippia as a source of medicinal drugs and its representation in native aromatic flora, little is known about the structural and secretion features of its trichomes. In this work, the secretory trichomes, occurring in vegetative and reproductive organs of Lippia stachyoides Cham., were studied on the morphological, ontogenetic, histochemical and ultrastructural views. Usual techniques of vegetal anatomy and ultrastructure were employed; in situ identification of the chemical composition of the substances present in the trichomes was performed according to histochemical tests. In L. stachyoides, the secretory trichomes are capitate and classified according to five morphological types which are widely distributed in the shoot, leaves and inflorescences. The histochemistry revealed that in types I and IV, hydrophilic compounds are predominant and that lipophilic substances predominate in the types II and V. In general, the ultrastructural features observed in each trichome type corroborate the histochemical analysis. The results of this work suggest that morphological variations of secretory trichomes in L. stachyoides are associated to the chemical composition of the secretion / Mestre

Na subfamília Bromelioideae o chamado Complexo Nidularioide apresenta gêneros intimamente relacionados que apresentam historicamente problemática circunscrição genérica. A busca por caracteres morfológicos, em especial os caracteres reprodutivos tem auxiliado a compreensão de processos evolutivos em diferentes grupos. Esse trabalho buscou descrever a estrutura anatômica do ovário e do rudimento seminal nas espécies do Complexo Nidularioide: Canistropsis billbergioides, Canistrum aurantiacum, Edmundoa lindenii, Neoregelia johannis, Nidularium innocentii e Wittrockia superba. Ovários dessas espécies em diferentes estádios do desenvolvimento foram coletados e fixados em glutaraldeído 1% e formaldeído 4%, lavados em tampão fosfato de sódio 0,1 M, pH 7,2, desidratados em série etílica (10- 100%), e incluídos em hidroxietilmetacrilato. Cortes de 4 μm de espessura foram montados em lâmina e corados com azul de toluídina O. Em todas as espécies analisadas foi observada a formação de aerênquima tipo esquizógeno no mesofilo ovariano. As espécies C. billbergioides, E. lindenii var. rosea, N. johannis, N. innocentii e Wittrockia superba apresentaram grande número de caracteres compartilhados, como a presença de três camadas de células no tegumento externo, epiderme nucelar e estrato parietal compostos por uma ou duas camadas de células. A espécie E. lindenii var. rosea apresentou tricomas epidérmicos na superfície do ovário, sendo esses tricomas descritos como uma nova morfologia de tricomas para a família Bromeliaceae. Considerando os caracteres observados, a espécie C. aurantiacum apresentou menor número de caracteres compartilhados com as demais espécies do Complexo Nidularioide. / In Bromelioideae subfamily, the so-called Nidularioid Complex presents intimately related genera, bearing historical generic circumscription issues. The search of morphological features, concerning mainly reproductive characters, has helped to enlighten evolution processes between different groups within the family. This work aimed to describe the ovary and ovule anatomical structure of the Nidularioid Complex species: Canistropsis billbergioides, Canistrum aurantiacum, Edmundoa lindenii var. rosea, Neoregelia johannis, Nidularium innocentii and Wittrockia superba. Ovaries in different development stages were collected and fixed in a 1% glutaraldehyde and 4% formaldehyde solution, washed in a sodium phosphate 0.1 M and 7.2 pH solution, and subsequently dehydrated in a crescent ethylic series, ranging from 10% to 100%; lately, the specimens were included in hydroxyethylmethacrylate. 4 μm cuts were mounted in glass blades, and stained with toluidine blue O. In all analyzed species a schizogenous type aerenchyma could be observed within the ovarian mesophyll. C. billbergioides, E. lindenii, N. johannis, N. innocentii and Wittrockia superba presented a great amount of common characters, such as a three layer cell in the outer tegument, nucellar epidermis and parietal tissue composed of two or more cell layers. E. lindenii var. rosea presented epidermic trichomes in the ovary surface, being these trichome described as a new kind of trichome morphology for the Bromeliaceae family. C. aurantiacum presented a minor quantity of common characters with the other analyzed species of the Nidularioid Complex.

Na subfamília Bromelioideae o chamado Complexo Nidularioide apresenta gêneros intimamente relacionados que apresentam historicamente problemática circunscrição genérica. A busca por caracteres morfológicos, em especial os caracteres reprodutivos tem auxiliado a compreensão de processos evolutivos em diferentes grupos. Esse trabalho buscou descrever a estrutura anatômica do ovário e do rudimento seminal nas espécies do Complexo Nidularioide: Canistropsis billbergioides, Canistrum aurantiacum, Edmundoa lindenii, Neoregelia johannis, Nidularium innocentii e Wittrockia superba. Ovários dessas espécies em diferentes estádios do desenvolvimento foram coletados e fixados em glutaraldeído 1% e formaldeído 4%, lavados em tampão fosfato de sódio 0,1 M, pH 7,2, desidratados em série etílica (10- 100%), e incluídos em hidroxietilmetacrilato. Cortes de 4 μm de espessura foram montados em lâmina e corados com azul de toluídina O. Em todas as espécies analisadas foi observada a formação de aerênquima tipo esquizógeno no mesofilo ovariano. As espécies C. billbergioides, E. lindenii var. rosea, N. johannis, N. innocentii e Wittrockia superba apresentaram grande número de caracteres compartilhados, como a presença de três camadas de células no tegumento externo, epiderme nucelar e estrato parietal compostos por uma ou duas camadas de células. A espécie E. lindenii var. rosea apresentou tricomas epidérmicos na superfície do ovário, sendo esses tricomas descritos como uma nova morfologia de tricomas para a família Bromeliaceae. Considerando os caracteres observados, a espécie C. aurantiacum apresentou menor número de caracteres compartilhados com as demais espécies do Complexo Nidularioide. / In Bromelioideae subfamily, the so-called Nidularioid Complex presents intimately related genera, bearing historical generic circumscription issues. The search of morphological features, concerning mainly reproductive characters, has helped to enlighten evolution processes between different groups within the family. This work aimed to describe the ovary and ovule anatomical structure of the Nidularioid Complex species: Canistropsis billbergioides, Canistrum aurantiacum, Edmundoa lindenii var. rosea, Neoregelia johannis, Nidularium innocentii and Wittrockia superba. Ovaries in different development stages were collected and fixed in a 1% glutaraldehyde and 4% formaldehyde solution, washed in a sodium phosphate 0.1 M and 7.2 pH solution, and subsequently dehydrated in a crescent ethylic series, ranging from 10% to 100%; lately, the specimens were included in hydroxyethylmethacrylate. 4 μm cuts were mounted in glass blades, and stained with toluidine blue O. In all analyzed species a schizogenous type aerenchyma could be observed within the ovarian mesophyll. C. billbergioides, E. lindenii, N. johannis, N. innocentii and Wittrockia superba presented a great amount of common characters, such as a three layer cell in the outer tegument, nucellar epidermis and parietal tissue composed of two or more cell layers. E. lindenii var. rosea presented epidermic trichomes in the ovary surface, being these trichome described as a new kind of trichome morphology for the Bromeliaceae family. C. aurantiacum presented a minor quantity of common characters with the other analyzed species of the Nidularioid Complex.

La différenciation cellulaire et la spécification des tissus biologiques dépendent en partie de l'établissement de programmes d'expression génétique caractéristiques. Ces programmes sont le résultat de l'interprétation de l'information génomique par des Facteurs de Transcription (TFs) se fixant à des séquences d'ADN spécifiques. Décoder cette information dans les génomes séquencés est donc un enjeu majeur. Dans une première partie, nous étudions l'interaction entre les TFs et leurs sites de fixation sur l'ADN. L'utilisation d'un modèle de Potts inspiré de la physique des verres de spin et de données de fixation à grande échelle pour plusieurs TFs de la drosophile et des mammifères permet de montrer que les sites de fixation exhibent des corrélations entre nucléotides. Leur prise en compte permet d'améliorer significativement la prédiction des sites de fixations sur le génome. Nous présentons ensuite Imogene, l'extension au cas des mammifères d'un algorithme bayésien utilisant la phylogénie afin d'identifier les motifs et modules de cis-régulation (CRMs) contrôlant l'expression d'un ensemble de gènes co-régulés, qui a précédemment été appliqué au cas de la régulation chez les drosophiles. Partant d'un ensemble d'apprentissage constitué d'un petit nombre de CRMs chez une espèce de référence, et sans connaissance a priori des TFs s'y fixant, l'algorithme utilise la sur-représentation et la conservation des sites de fixation chez des espèces proches pour prédire des régulateurs putatifs ainsi que les CRMs génomiques sous-tendant la co-régulation. Nous montrons en particulier qu'Imogene peut distinguer des modules de régulation conduisant à différents motifs d'expression génétique sur la seule base de leur séquence ADN. Enfin, nous présentons des applications de ces outils de modélisation à des cas biologiques réels : la différenciation des trichomes chez la drosophile, et la différenciation musculaire chez la souris. Dans les deux cas, les prédictions ont été validées expérimentalement en collaboration avec des équipes de biologistes, et pointent vers une grande flexibilité des processus de cis-régulation.

Forward genetic screen was performed in Arabidopsis thaliana to isolate novel genes involved in leaf development. The tarani (tni) mutant was selected for further study based on its unique cup-shaped lamina with +ve Gaussian curvature. We show that the larger size of tni leaves is due to rapid growth rate due to excess and prolonged cell division. We monitored the front of the receding cell division zone as a function of time and showed that the shape of the front is more concave compared to wild type, leading to positive curvature. Application of gibberellic acids (GA) synthesis inhibitor rescued the positive curvature of tni suggesting a role for GA in maintaining leaf flatness. Overexpression of cell cycle inhibitor KRP2 also flattened the leaf, confirming a role of cell division. The floral organs and seed are also larger in the tni mutant. Besides growth, tni trichomes are hyper-branched which usually happens when there is more endoreduplication. We found that the nuclei of tni trichomes are larger than wild type nuclei, suggesting increased DNA content. Genetic interaction studies showed that TNI works independent of other trichome branching genes such as with TRYPTICHON and FURCA1. Map-based cloning showed that tni is positioned on left arm of the 3rd chromosome. Using molecular markers, we narrowed down to interval to a 65 kb region, which codes for 19 genes. Sequencing several of them revealed a G→A transition at the 3rd intron - 4th exon junction of At3g20630 gene. RT-PCR analysis showed the presence of an additional full-length transcript with extra un-spliced 3rd intron. Overexpression of this un-spliced variant in wild type plants produced phenotypes like hyperbranched trichomes and cup-shaped leaves; plus additional phenotypes like organ fusion and organ polarity defects. Complementation and allelic tests confirmed that TNI codes for AtUBP14, an ubiquitin protease. The tni plants have longer stem and roots which grow at faster rate compared to wild type. Confocal microscopic analysis of mature embryos showed that both shoot (SAM) and root apical meristems (RAM) of tni plants are larger in size. In RAM, the numbers of quiescent center (QC) cells and stem cells have increased in tni plants. The tni inflorescence and flowers are bigger than wild type in size. Also the degree of axillary shoots has increased in the tni plants. Overexpression of the splice variant of TNI produced undifferentiated callus-like structures in the shoot apex and in hypocotyl. All these phenotypes show that TNI is involved in meristem proliferation. The tni siliques produced many un-fertilized ovules and shrunken and malformed seeds suggesting gametic and/or embryo lethality. We observed that tni embryos were mis-patterned at various stages of development. Following the cell division pattern shows that cells arising from the ‘basal cell’ of the embryo take apical cell fate in tni embryos. The topmost cell of the suspensor, which is also the precursor cell of RAM, is not specified as hypophysial cell in several tni embryos. In the forward genetic screen, we isolated another mutant called tooth (tth), which has deeper serrations at the leaf margin and narrower leaves compared to wild type. It has been mapped to the longer arm of the 2nd chromosome. Genetic interaction studies show that tth is not allelic to other serration mutants such as serrate and mir164a.

Introducing effective irrigation management in arid and semi-arid regions, like most areas of South Africa, is an indispensable way of maximising crop yield and enhancing productivity of scarce freshwater resources. Holistic improvements in agricultural water management could be realised through integrating the knowledge of crop-specific water requirements. In order to develop effective irrigation schedules for rose-scented geranium (Pelargonium capitatum x P. radens), greenhouse and field experiments were conducted at the Hatfield Experimental Farm of the University of Pretoria, Pretoria, South Africa, from 28 October 2004 to 2006. Results from 20, 40, 60 and 80% maximum allowable depletion (MAD) levels of the plant available soil water (ASW) indicated that plant roots extracted most of the soil water from the top 40 cm soil layer, independent of the treatment. Both essential oil yield and fresh herbage mass responded positively to high soil water content. Increasing the MAD level to 60% and higher resulted in a significant reduction in herbage mass and essential oil yields. An increase in the degree of water stress apparently increased the essential oil concentration (percentage oil on fresh herbage mass basis), but its contribution to total essential oil yield (kg/ha oil) was limited. There was no significant relationship between MAD level and essential oil composition. For water saving without a significant reduction in essential oil yield of rose-scented geranium, a MAD of 40% of ASW is proposed. Response of rose-scented geranium to a one-month irrigation withholding period in the second or third month of regrowth cycles showed that herbage mass and oil yield were positively related. Herbage yield was significantly reduced when the water stress period was imposed during the third or fourth month of regrowth. A remarkable essential oil yield loss was observed only when the plants were stressed during the fourth month of regrowth. Essential oil content (% oil on fresh herbage mass basis) was higher in stressed plants, especially when stressed late, but oil yield dropped due to lower herbage mass. The relationship between essential oil composition and irrigation treatments was not consistent. Water-use efficiency was not significantly affected by withholding irrigation in the second or in the third month of regrowth. With a marginal oil yield loss, about 330 to 460 m3 of water per hectare per regrowth cycle could be saved by withholding irrigation during the third month of regrowth. The overall results highlighted that in water-scarce regions withholding irrigation during either the second or the third month of regrowth in rose-scented geranium could save water that could be used by other sectors of society. In greenhouse pot experiments, rose-scented geranium was grown under different irrigation frequencies, in two growth media. Irrigation was withheld on 50% of the plants (in each plot) for the week prior to harvesting. Herbage and essential oil yields were better in the sandy clay soil than in silica sand. Essential oil content (% oil on fresh herbage mass basis) apparently increased with a decrease in irrigation frequency. Both herbage and total essential oil yields positively responded to frequent irrigation. A one-week stress period prior to harvesting significantly increased essential oil content and total essential oil yield. Hence, the highest essential oil yield was obtained from a combination of high irrigation frequency and a one-week irrigation-withholding period. In the irrigation frequency treatments, citronellol and citronellyl formate contents tended to increase with an increase in the stress level, but the reverse was true for geraniol and geranyl formate. Leaf physiological data were recorded during the terminal one-week water stress in the glasshouse pot trial. Upon rewatering, stomatal conductance (Gs) and transpiration rate (Rt) were significantly lower in the less often irrigated than in the more often irrigated treatments, while leaf water potential (yw) and relative water content (RWC) were the same for all plants, indicating that water stress had an after-effect on Gs and Rt. At the end of the stress period, Gs, Rt, yw and RWC were lower in the plants from the more often irrigated than from the less often irrigated treatments. Irrespective of irrigation treatment, one type of non-glandular and two types (different in shape and size) of glandular trichomes were observed. In water stressed-conditions, stomata and trichome densities increased, while the total number of stomata and trichomes per leaf appeared to remain more or less the same. Water stress conditions resulted in stomatal closure. / Thesis (PhD)--University of Pretoria, 2009. / Plant Production and Soil Science / unrestricted

No description available.