A escassez de água é um dos fatores mais limitantes à produção agrícola. O entendimento dos fatores que regem a extração da água do solo por plantas e a sua distribuição ao longo do sistema radicular em condições hidráulicas contrastantes é importante para o ajuste fino de modelos hidrológicos que servem de referência para modelos de produção vegetal e meteorológicos, entre outros. Com a finalidade de contribuir com o conhecimento sobre a dinâmica da água na rizosfera, nesta dissertação um modelo de partição de extração de água do solo pelas raízes foi descrito e testado experimentalmente. Para poder medir a partição da extração de água do solo por raízes impondo condições contrastantes de teor de água foi criado um ambiente artificial, um lisímetro com dois compartimentos A e B separados fisicamente (split-pot). Foram confeccionados quatro desses lisímetros, preenchidos com material de um solo de textura média e plantados com duas plantas de sorgo (Sorghum bicolor (L.) Moench), dividindo o sistema radicular ao meio entre os compartimentos. Sensores de TDR e tensiômetros foram instalados nos lisímetros para monitoramento do teor de água no solo e referencia para irrigação, respectivamente. O manejo da irrigação adotado foi constituído de quatro fases: I - irrigação apenas do compartimento B e secagem do compartimento A (07/05 25/05); II - secagem dos dois compartimentos (26/05 05/06); III - irrigação do compartimento A e secagem do compartimento B (06/06 14/06); IV - secagem dos dois compartimentos (15/06 - 22/06). O material de solo utilizado foi analisado quanto a suas propriedades hidráulicas. Após o fim do período de monitoramento os lisímetros foram desmontados e os parâmetros radiculares determinados. Para avaliar o desempenho do modelo de extração radicular compararam-se os dados observados de teor de água (obs) com os previstos pelo modelo (mod), utilizando-se a raiz do erro médio quadrático (RMSE) como indicador quantitativo. Incluiu-se um fator de correção para atividade e distribuição do sistema radicular. Para as quatro unidades experimentais, os valores do teor de água variaram devido às lâminas de irrigação aplicadas e a extração de água pela planta. Observaram-se, ainda, muito mais valores positivo de modelados do que observados, o que indica que a resistência hidráulica interna das raízes e mecanismos que impedem o refluxo de água ao solo, não considerados pelo modelo, podem, na verdade, ter um papel importante nas relações hídricas na rizosfera. Concluiu-se que o experimento permitiu fazer observações da extração radicular em condições hidráulicas contrastantes de seu sistema radicular. As plantas demonstraram preferência por extrair água dos compartimentos mais úmidos, interrompendo a exploração dos mais secos. Em diversas ocasiões a liberação da água ao solo foi observada nos compartimentos mais secos. Utilizando-se um fator de eficiência radicular de 0,015, o modelo testado descreveu razoavelmente bem as observações. / Water shortage is one of the most limiting factors for agricultural production. The understanding of factors that rule the extraction of soil water by plants and its distribution along the root system under contrasting hydraulic conditions is important for fine-tuning hydrological models which are a reference for crop growth models, meteorological models, among others. Aiming to contribute with the understanding of water dynamics in the rhizosphere, a model for the description of root water extraction partition was described and experimentally tested in this dissertation. To measure the root water extraction partition under contrasting hydraulic conditions an artificial environment was created: a split-pot lysimeter with two physically divided compartments A and B. Four of these lysimeters were constructed, filled with a medium textured soil and populated by two sorghum (Sorghum bicolor (L.) Moench) plants whose root systems were divided among the compartments. TDR and tensiometer equipment was installed in the lysimeters to measure soil water content and as a reference for irrigation, respectively. Irrigation management consisted of four phases: I - irrigation only in compartment B, drying out compartment A (07/May 25/May); II no irrigation, drying out of both compartments (26/May 05/June); III - irrigation only in compartment A, drying out compartment B (06/June 14/June); IV - no irrigation, drying out of both compartments (15/June 22/June). Soil hydraulic properties were determined in laboratory. At the end of the experimental period, lysimeters were disassembled and root system parameters were determined. To evaluate the performance of the root water extraction model, observed water contents were compared with model predictions, using the root means square error (RMSE) as quantitative index. A correction factor for root activity and distribution was included. Water contents were observed to vary in the four lysimeters due to irrigation and root water extraction. Model predictions showed much more positive values of than observed, suggesting that internal root resistance and mechanisms impeding reflux from root to soil, not considered by the model may play an important role in rhizosphere water relations. It is concluded that the experiment permitted to observe root water extraction under contrasting hydraulic conditions in the root system. Plants showed preference for water extraction from the wetter compartments, interrupting the exploitation of the dryer ones. On several occasions, a hydraulic lift (water transfer from roots to soil) was observed in the dry compartments. Using a root system efficiency factor of 0.015, the tested model described the observations reasonably well.

A escassez de água é um dos fatores mais limitantes à produção agrícola. O entendimento dos fatores que regem a extração da água do solo por plantas e a sua distribuição ao longo do sistema radicular em condições hidráulicas contrastantes é importante para o ajuste fino de modelos hidrológicos que servem de referência para modelos de produção vegetal e meteorológicos, entre outros. Com a finalidade de contribuir com o conhecimento sobre a dinâmica da água na rizosfera, nesta dissertação um modelo de partição de extração de água do solo pelas raízes foi descrito e testado experimentalmente. Para poder medir a partição da extração de água do solo por raízes impondo condições contrastantes de teor de água foi criado um ambiente artificial, um lisímetro com dois compartimentos A e B separados fisicamente (split-pot). Foram confeccionados quatro desses lisímetros, preenchidos com material de um solo de textura média e plantados com duas plantas de sorgo (Sorghum bicolor (L.) Moench), dividindo o sistema radicular ao meio entre os compartimentos. Sensores de TDR e tensiômetros foram instalados nos lisímetros para monitoramento do teor de água no solo e referencia para irrigação, respectivamente. O manejo da irrigação adotado foi constituído de quatro fases: I - irrigação apenas do compartimento B e secagem do compartimento A (07/05 25/05); II - secagem dos dois compartimentos (26/05 05/06); III - irrigação do compartimento A e secagem do compartimento B (06/06 14/06); IV - secagem dos dois compartimentos (15/06 - 22/06). O material de solo utilizado foi analisado quanto a suas propriedades hidráulicas. Após o fim do período de monitoramento os lisímetros foram desmontados e os parâmetros radiculares determinados. Para avaliar o desempenho do modelo de extração radicular compararam-se os dados observados de teor de água (obs) com os previstos pelo modelo (mod), utilizando-se a raiz do erro médio quadrático (RMSE) como indicador quantitativo. Incluiu-se um fator de correção para atividade e distribuição do sistema radicular. Para as quatro unidades experimentais, os valores do teor de água variaram devido às lâminas de irrigação aplicadas e a extração de água pela planta. Observaram-se, ainda, muito mais valores positivo de modelados do que observados, o que indica que a resistência hidráulica interna das raízes e mecanismos que impedem o refluxo de água ao solo, não considerados pelo modelo, podem, na verdade, ter um papel importante nas relações hídricas na rizosfera. Concluiu-se que o experimento permitiu fazer observações da extração radicular em condições hidráulicas contrastantes de seu sistema radicular. As plantas demonstraram preferência por extrair água dos compartimentos mais úmidos, interrompendo a exploração dos mais secos. Em diversas ocasiões a liberação da água ao solo foi observada nos compartimentos mais secos. Utilizando-se um fator de eficiência radicular de 0,015, o modelo testado descreveu razoavelmente bem as observações. / Water shortage is one of the most limiting factors for agricultural production. The understanding of factors that rule the extraction of soil water by plants and its distribution along the root system under contrasting hydraulic conditions is important for fine-tuning hydrological models which are a reference for crop growth models, meteorological models, among others. Aiming to contribute with the understanding of water dynamics in the rhizosphere, a model for the description of root water extraction partition was described and experimentally tested in this dissertation. To measure the root water extraction partition under contrasting hydraulic conditions an artificial environment was created: a split-pot lysimeter with two physically divided compartments A and B. Four of these lysimeters were constructed, filled with a medium textured soil and populated by two sorghum (Sorghum bicolor (L.) Moench) plants whose root systems were divided among the compartments. TDR and tensiometer equipment was installed in the lysimeters to measure soil water content and as a reference for irrigation, respectively. Irrigation management consisted of four phases: I - irrigation only in compartment B, drying out compartment A (07/May 25/May); II no irrigation, drying out of both compartments (26/May 05/June); III - irrigation only in compartment A, drying out compartment B (06/June 14/June); IV - no irrigation, drying out of both compartments (15/June 22/June). Soil hydraulic properties were determined in laboratory. At the end of the experimental period, lysimeters were disassembled and root system parameters were determined. To evaluate the performance of the root water extraction model, observed water contents were compared with model predictions, using the root means square error (RMSE) as quantitative index. A correction factor for root activity and distribution was included. Water contents were observed to vary in the four lysimeters due to irrigation and root water extraction. Model predictions showed much more positive values of than observed, suggesting that internal root resistance and mechanisms impeding reflux from root to soil, not considered by the model may play an important role in rhizosphere water relations. It is concluded that the experiment permitted to observe root water extraction under contrasting hydraulic conditions in the root system. Plants showed preference for water extraction from the wetter compartments, interrupting the exploitation of the dryer ones. On several occasions, a hydraulic lift (water transfer from roots to soil) was observed in the dry compartments. Using a root system efficiency factor of 0.015, the tested model described the observations reasonably well.

Estudos de adubação nitrogenada em cana-de-açúcar normalmente se restringem em avaliar os efeitos no crescimento da parte-aérea. Há evidências de que a fertilização nitrogenada favorece o crescimento de raízes, a absorção de nutrientes e a produtividade da cultura. Objetivou-se com o trabalho avaliar o desenvolvimento de raízes e produtividade da cana-de-açúcar (SP81 3250) nos ciclos de cana-planta e 1ª soca. Foram conduzidos três experimentos, um em LATOSSOLO VERMELHO AMARELO eutrófico (LVAe) e outro em LATOSSOLO VERMELHO distrófico típico (LVd) (ambos de textura média) e um em LATOSSOLO VERMELHO eutrófico (LVe) argiloso. Na cana-planta os tratamentos constaram de doses de nitrogênio (N) de 40, 80 e 120 kg ha-1 e uma testemunha (sem N mineral), em blocos ao acaso, com quatro repetições. Na cana-soca cada parcela da cana-planta foi dividida em quatro subparcelas, às quais foram aplicadas doses de 50, 100 e 150 kg ha-1 N e uma testemunha. No 1º corte o sistema radicular foi avaliado em todos os tratamentos nos três solos. No 2º corte, o sistema radicular foi avaliado somente nas subparcelas dos tratamentos de plantio testemunha e 120 kg ha-1 N, no LVAe e LVd. Para o experimento no solo LVe, somente nas subparcelas testemunha e 150 kg ha-1 N das parcelas principais testemunha e 120 kg ha-1 N foi avaliado o sistema radicular da cana soca. A amostragem de raízes com sonda resultou em massa de raízes que não diferiu da avaliação em monólito, indicando que esse método pode ser usado para avaliações de raízes de cana-de-açúcar. A fertilização nitrogenada de plantio promoveu maior concentração de raízes até 0,2 m no LVd. No ciclo da cana-planta, no LVAe e no LVd houve crescimento pronunciado de raízes de outubro de 2005 a fevereiro de 2006, com redução da massa de fevereiro até a colheita, porém sem afetar o desenvolvimento da parte aérea. Em fevereiro, 20% do N acumulado na planta toda foi encontrado nas raízes, diminuindo para 5% na colheita como decorrência da redução da massa de raízes. As doses de N no plantio favoreceram o crescimento de raízes e a produtividade de colmos no LVAe e no LVe, e o acúmulo de sacarose no LVd. As doses de N na soqueira favoreceram a produtividade de colmos e açúcar nos três solos. No 1º corte, foi obtida maior produtividade de colmos (152 t ha-1) e menor massa de raízes (1,35 t ha-1) no LVe em relação ao LVAe e LVd (139 e 145 t ha-1 de colmos e 2,5 e 2,4 t ha-1 de raízes, respectivamente). Em relação ao 1º corte, a produtividade do 2º corte se manteve estável no LVd (120 t ha-1) e diminuiu drasticamente no LVe (80 t ha-1). Esse fato foi devido à pequena massa de raízes no LVe no 1º corte, tendo em vista que nas duas áreas ocorreu acentuado déficit hídrico em alguns meses antes e após o 1º corte. A adubação nitrogenada de soqueira favoreceu o crescimento de raízes somente no LVe, porém a massa de raízes diminuiu do 1º para o 2º corte, enquanto que no LVAe e no LVd a massa permaneceu constante. / Studies of nitrogen fertilization in sugarcane are usually restricted to evaluations of the effects on growth and productivity of the shoots. There are evidences that nitrogen fertilization favors the growth of roots, the absorption of nutrients and sugarcane productivity. This work was designed to evaluate root development and sugarcane productivity (SP81 3250) in the crop cycles of the cane-plant and of the first ratoon. Three experiments were conducted in a randomized blocks design, with four replications, in three different soils, a Typic Eutrustox (TE) and an Arenic Kandiustults (AK) (both of medium texture), and a clayey Rhodic Eutrustox (RE). Treatments for the cane-plant were nitrogen (N) rates of 0, 40, 80 and 120 kg ha-1 N. In the first ratoon crop each plot of cane-plant was split in four subplots to which rates of 0, 50, 100 and 150 kg ha-1 of N was applied. In the first harvest, the root system was evaluated in all of the treatments applied on the three soils (TE, AK and RE), whereas in the second harvest the root system was evaluated only for the subplots of the planting treatments control and 120 kg ha-1 N in TE and AK. For the experiment in the RE soil, only control and 150 kg ha-1 N subplots of the control and 120 kg ha-1 N main plots had the ratoon root system evaluated. The sampling of roots with probe resulted in a mass of roots that did not differ from the monolith evaluation, indicating that this method can be used for the evaluation of sugarcane roots. Nitrogen fertilization at planting resulted in a higher concentration of roots in the top 0.2 m in AK. There was a pronounced growth of roots in TE and in AK from October, 2005 to February, 2006, and a reduction of the mass from February until harvest; however development of the above ground part of the plant was not affected. Until February, about 20% of accumulated N in the whole plant was found in the roots, decreasing to 5% at harvest, as a consequence of root mass reduction. The N rates applied to the cane-plant favored the roots growth and crop productivity in TE and RE, and the sucrose accumulation in AK. The rates of fertilizer-N in the ratoon favored the productivity of stalks and sugar yield in the three soils. In the first harvest, it was obtained a larger productivity of stalks (152 t ha-1) and a smaller mass of roots (1.35 t ha-1) in RE in relation to TE and AK (139 and 145 t ha-1 of stalks and 2.5 and 2.4 t ha-1 of roots, respectively). The productivity of the second harvest was similar to that of the first harvest in AK (120 t ha-1), but it decreased drastically in RE (80 t ha-1), as a consequence of the small mass of roots in RE in the first harvest, attributed to a high water deficit in the months prior to and after harvest. Nitrogen fertilization applied after the first harvest influenced root growth only in the RE soil; however the mass of roots decreased from the first to the second harvest while in the TE and AK soils the root mass remained constant.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-05-23T19:32:21Z No. of bitstreams: 1 2010 - Dan?bia Gon?alves Ribeiro.pdf: 824606 bytes, checksum: dd284e46bd5222c0f71d865d8ad108b3 (MD5) / Made available in DSpace on 2017-05-23T19:32:21Z (GMT). No. of bitstreams: 1 2010 - Dan?bia Gon?alves Ribeiro.pdf: 824606 bytes, checksum: dd284e46bd5222c0f71d865d8ad108b3 (MD5) Previous issue date: 2010-02-23 / Information about the mineral nutrition of new varieties of pineapple (Ananas comosus), and about the nutrient absorption of the preformed root system of micropropagated plantlets, is lacking. This work had the objective to evaluate the contribution of the preformed roots of pineapple seedlings cultivar ?Vit?ria? in plant growth and nitrogen (N) absorption in the first months of acclimatization of the seedlings. A greenhouse experiment was conducted in the Department of Fitotecnia of UFRRJ, Serop?dica (RJ). The experimental design was randomized blocks in an incomplete factorial design, with three treatments of root pruning (without pruning, half pruning and total pruning), four times of N application (0, 30, 60 and 90 days after transplant ? DAT), four plant harvests at different growth stages (30, 60, 90 and 120 DAT), and five replications, summing 150 experimental units. The substrate was the A horizon of Planosol in 5 kg pots. At harvests, the shoot and root dry weight was measured. The root systems were scanned and their area and length determined by digital image analysis. Concentrations and content of N in shoots and roots, and the influx of N into roots, were determined. Plants without root pruning produced higher shoot mass at every harvest. The application of N at 0 or 30 DAT provided a larger shoot mass at 60 and 120 DAT. After 120 DAT, the plants that received root pruning had lower root mass, area and length, than those plants without pruning. Time of N application did not affect the mass, area or length of roots. The N application after 60 DAT caused higher biomass allocation to roots, increasing root:shoot ratio. Plants without root pruning showed higher specific root area and length at 30 and 60 DAT, hence thinner roots. Time of N application did not affected the N accumulation in shoots, but plants without root pruning and that received N at 0 and 30 DAT had a dilution effect of N, with lower shoot N concentration. Total root pruning provided lower N accumulation in plants. Influx of N per root area and root length was not affected by time of N application. Influx of N into roots was higher in plants that received root pruning, since they presented younger roots with higher absorption activity. It is concluded that the preformed root system of pineapple plantlets is able to absorb N during the first months after planting, and that the practice of pruning the root system, entirely or partially, leads to lower initial plant growth. / H? car?ncia de informa??es sobre a nutri??o mineral das novas variedades de abacaxi (Ananas comosus), bem como sobre o manejo do sistema radicular pr?-formado das mudas micropropagadas e sua efici?ncia na absor??o de nutrientes. Este trabalho teve como objetivo avaliar a contribui??o das ra?zes pr?-formadas em mudas micropropagadas de abacaxizeiro cultivar ?Vit?ria? no crescimento e absor??o de nitrog?nio (N) nos primeiros meses de aclimata??o das mudas. Foi conduzido um experimento em casa de vegeta??o no Departamento de Fitotecnia da UFRRJ, em Serop?dica (RJ). O delineamento experimental foi de blocos ao acaso em esquema fatorial incompleto, com tr?s tratamentos de poda de raiz (sem poda, meia poda e poda total), quatro ?pocas de aplica??o de N (aos 0, 30, 60 e 90 dias ap?s transplante ? DAT), quatro coletas em diferentes est?dios de crescimento (aos 30, 60, 90 e 120 DAT) e cinco repeti??es, totalizando 150 unidades experimentais. O substrato foi horizonte A de Planossolo em vasos de 5 kg. Nas coletas, foi mensurada a massa seca da parte a?rea e da raiz. Os sistemas radiculares foram digitalizados e sua ?rea e comprimento determinados por an?lise digital de imagens. Foram determinados os teores e conte?dos de N na parte a?rea e ra?zes, e o influxo de N nas ra?zes. As plantas sem poda de raiz produziram maior massa de parte a?rea em todas as ?pocas de avalia??o. A aplica??o do adubo nitrogenado aos 0 ou 30 DAT proporcionou maior massa de parte a?rea aos 60 e aos 120 DAT. Decorridos 120 DAT, as plantas que receberam poda de raiz apresentaram massa, ?rea e comprimento radicular inferiores ?s que n?o receberam. A ?poca de aplica??o do adubo nitrogenado n?o influenciou na massa, ?rea e comprimento radicular. A aplica??o do N ap?s 60 DAT causou maior aloca??o de biomassa nas ra?zes, aumentando a rela??o raiz:parte a?rea. As plantas sem poda de raiz apresentaram maior ?rea radicular espec?fica e comprimento radicular espec?fico aos 30 e 60 DAT, ou seja, ra?zes mais finas. A ?poca de aplica??o de N n?o modificou a acumula??o de N na parte a?rea, mas as plantas sem poda de raiz e com aplica??o de N aos 0 e 30 DAT apresentaram efeito de dilui??o do N, com menor teor de N na parte a?rea. A poda total proporcionou menor acumula??o de N nas plantas. O influxo de N por ?rea e por comprimento radicular n?o sofreu influ?ncia da ?poca de aplica??o de N. O influxo radicular de N foi maior nas plantas que receberam poda total, por apresentarem ra?zes mais novas, com maior atividade de absor??o. Pode-se concluir que o sistema radicular pr?-formado presente nas mudas micropropagadas de abacaxi se mostrou apto em absorver o N nos primeiros meses ap?s o plantio, e que a pr?tica da poda do sistema radicular, total ou parcial, acarreta menor desenvolvimento inicial das plantas.

Les auxines sont des composants clés essentiels pour le contrôle du développement des racines et la réponse aux contraintes environnementales en raison de leur rôle central dans la division, l’élongation et la différenciation cellulaires. L’auxine endogène, acide indole-3-butyrique (IBA), bien que moins abondante et moins connue que l'acide indole-3-acétique (IAA), joue un rôle important dans le développement racinaire, en particulier lors de la formation des racines latérales et de l'élongation des poils absorbants. Il est généralement admis que les fonctions de l’IBA dépendent entièrement de la conversion peroxysomale de l’IBA en IAA. Bien que nos connaissances concernant les enzymes impliquées dans cette conversion soient très avancées, nous en savons peu sur les mode de régulation de ces fonctions. Au cours de ma thèse, j'ai démontré que les fonctions de l’IBA lors de l'induction des racines latérales et de l'élongation des poils absorbants dépendent du glutathion, un petit tripeptide rédox qui constitue l'une des molécules les plus importantes impliquées dans les réponses des plantes au stress oxydatif. De plus, j'ai démontré que le lien entre le glutathion et l'auxine IBA est essentiel pour les réponses à l’auxine dans la zone de transition de la racine primaire. Ce contrôle des fonctions de l’IBA par le glutathion pourrait être déterminant dans des conditions de stress abiotiques telles que la carence en phosphore.Une des fonctions du glutathion étant de réduire des réductases de fonctions thiols, les glutaredoxines (GRX), nous avons recherché si certaines GRX sont impliquées dans le développement racinaire. Nous avons constaté que ROXY19 et GRXS17 sont essentiels à la croissance des racines primaires et que ces deux GRX sont également impliqués, mais dans des rôles différents, lors du développement des racines latérales. Un crible suppresseur des phénotypes racinaires du mutant grxs17 avait été mis en place dans le laboratoire. J'ai utilisé des approches bio-informatiques pour isoler les mutations causales après reséquençage du génome de candidats capables de restaurer la croissance des racines primaires et / ou le développement normal des primordia des racines latérales. Malheureusement, cette approche ne nous a pas encore permis d’isoler de nouveaux acteurs. Cependant, elle jette les bases d’un futur grand progrès dans la compréhension de la manière dont GRXS17 contrôle le système racinaire.En conclusion, les résultats de ma thèse soulignent l’importance du glutathion et des glutarédoxines dans le contrôle de la plasticité du système racinaire et lors de conditions de stress abiotiques, notamment via la modulation de la voie auxinique IBA. / Auxins are critical key components for the control of root development and response to environmental constraints by its pivotal roles in cell division, elongation, and cell differentiation. The endogenous auxin Indole-3-butyric acid (IBA), although less abundant than the better-known Indole-3-Acetic Acid (IAA), plays important roles during root development especially during the formation of lateral roots and root hairs elongation. It is generally accepted that IBA functions are fully dependent on peroxisomal IBA-to-IAA conversion. While there is a great advance in our knowledge regarding the enzymes involved in the peroxisomal conversion of IBA-to-IAA, little is known about the mechanisms that modulate its functions. During my thesis, I demonstrated that the IBA functions during the induction of lateral roots and root hairs elongation are dependent on glutathione, which is a small redox tripeptide that constitutes one of the most important molecules involved in plant responses to oxidative stresses. Moreover, I demonstrated that the link between glutathione and the auxin IBA is critical for the auxin distribution that takes place in the transition zone of the primary root. The relevance of the control of IBA functions by glutathione might be determinant during abiotic stress conditions such as phosphorus deprivation.Since glutathione is a reducer of thiol reductases glutaredoxins (GRXs), we investigate if some GRXs are involved in root development. We found that ROXY19 and GRXS17 are critical for the primary root growth, and both GRX proteins play different roles during the formation of lateral roots. Based on this root phenotype, a suppressor screen in grxs17 background had been set up in the lab. I developed bioinformatic pipelines to isolate causal mutations from genome resequencing of candidates that are able to restore the primary root growth and/or the normal development of lateral roots primordia. Unfortunately, this approach did not yet allow us to isolate new actors, however it builds foundations for future big advance in understanding how glutaredoxins control the root system.In conclusion, the results showed in my Ph.D. thesis highlight the importance of glutathione and glutaredoxins in the control of the root system plasticity and during abiotic stress conditions, particularly via the modulation of the auxinic IBA pathway.

Doctor of Philosophy(PhD) / It is generally accepted that tree roots can reinforce soil and improve the stability of vegetated slopes. Tree root reinforcement is also recognised in riverbanks although the contribution that the roots make to bank stability has rarely been assessed due to the reluctance of geomorphologists to examine riverbank stability by geomechanical methods that allow for the inclusion of quantified biotechnical parameters. This study investigates the interaction between alluvial soil and the roots of four southeastern Australian riparian trees. It quantifies the amount and distribution of root reinforcement present beneath typically vegetated riverbanks of the upper Nepean River, New South Wales, and examines the effect of the reinforcement on the stability of these banks. The ability of a tree to reinforce the soil is limited by the spatial distribution of its root system and the strength that the roots impart to the soil during shear. These two parameters were determined for the following four species of native riparian tree: Casuarina glauca, Eucalyptus amplifolia, Eucalyptus elata, and Acacia floribunda. The four species all exhibit a progressive reduction in the quantity of root material both with increasing depth and with increasing lateral distance from the tree stem. In the vertical direction there are two distinct zones that can be described. The first occurs from between 0 and approximately 15 % of the maximum vertical depth and consists of approximately 80 % of the total root material quantity. In this zone the root system consists of both vertical and lateral roots, the size and density of which varies between species. The second zone occurs below approximately 15 % of the maximum vertical depth and consists primarily of vertical roots. The quantity of root material in this zone decreases exponentially with depth due to the taper of individual roots. The earth reinforcement potential in terms of both geometric extent and the quantity of root material expressed as the Root Area Ratio (RAR) varies significantly from species to species. E. elata exhibited the highest values of RAR in soil zones beneath it while E. amplifolia reinforced a greater volume of soil than any of the other species examined. The increased shear resistance (Sr) of alluvial soil containing roots was measured by direct in-situ shear tests on soil blocks beneath a plantation. For three of the species (C. glauca, E. amplifolia, E. elata) Sr increased with increasing RAR measured at the shear plane, in a similar linear relationship. The shear resistance provided by A. floribunda roots also increased with increasing RAR at the shear plane but at a much greater rate than for the other three species. This is attributable to A. floribunda’s greater root tensile strength and therefore pull-out resistance, as well as its smaller root diameters at comparative RARs which resulted in a greater proportion of roots reaching full tensile strength within the confines of the test. Tree roots fail progressively in this system. Therefore determining the increased shear strength from the sum of the pull-out or tensile strengths of all individual roots and Waldron’s (1977) and Wu et al’s (1979) simple root model, would result in substantial over estimates of the overall strength of the soil-root system. The average difference between Sr calculated in this manner and that measured from direct in-situ shear tests is 10.9 kPa for C. glauca, 19.0 kPa for E. amplifolia, 19.3 kPa for E. elata, and 8.8 kPa for A. floribunda. A riverbank stability analysis incorporating the root reinforcement effect was conducted using a predictive model of the spatial distribution of root reinforcement beneath riparian trees within the study area. The model is based on measurements of juveniles and observations of the rooting habits of mature trees. It indicates that while the presence of vegetation on riverbank profiles has the potential to increase stability by up to 105 %, the relative increase depends heavily on the actual vegetation type, density, and location on the bank profile. Of the species examined in this study the greatest potential for improved riverbank stability is provided by E. amplifolia, followed by E. elata, A. floribunda, and C. glauca. The presence of trees on banks of the Nepean River has the potential to raise the critical factor of safety (FoS) from a value that is very unstable (0.85) to significantly above 1.00 even when the banks are completely saturated and subject to rapid draw-down. It is likely then that the period of intense bank instability observed within this environment between 1947 and 1992 would not have taken place had the riparian vegetation not been cleared prior to the onset of wetter climatic conditions. Typical ‘present-day’ profiles are critically to marginally stable. The introduction of vegetation could improve stability by raising the FoS up to 1.68 however the selection of revegetation species is crucial. With the placement of a large growing Eucalypt at a suitable spacing (around 3-5 m) the choice of smaller understorey trees and shrubs is less important. The effect of riparian vegetation on bank stability has important implications for channel morphological change. This study quantifies the mechanical earth reinforcing effect of some native riparian trees, thus allowing for improved deterministic assessment of historical channel change and an improved basis for future riverine management.

Root systems are a fundamental concept in the theory of Lie algebra. In this thesis, we will use two different kind of graphs to represent the group generated by reflections acting on the elements of the root system. The root systems we are interested in are those of type A2, B2 and G2. After drawing the graphs, we will study the algebraic groups corresponding to those root systems. We will use three different techniques to give a geometric description of the homogeneous spaces G/P where G is the algebraic group corresponding to the root system and P is one of its parabolic subgroup. Finally, we will make a link between the graphs and the multiplication of basis elements in the Chow group CH(G/P).

科学研究費補助金 研究種目:一般研究(C) 課題番号:026600124 研究代表者:巽 二郎 研究期間:1990-1991年度

ABSTRACT This pilot study examines the knowledge about tree root systems amongst five tree planting professionals. The aim is to find out the professionals’ collective knowledge of the nature of root systems of various trees used in green areas. Furthermore; to explore how the professionals adapt landscaped green areas to the tree root properties in a sustainable manner. Questions: Which tree species have special root properties to consider and how do the professionals utilize this knowledge? And: How do the professionals in general adjust planting according to the root systems of trees in areas to create sustainable green environments? Interviews with the professionals were performed. Four of the five interviewees expressed that they had no root systems in mind when they chose trees to an area. However they considered properties such as wet soil, clay soil, sandy soil and the urban environment when they decided on the trees for an area. The interviewees discussed 22 different trees and their root systems and what kind of adaptations in landscaping they would make for the special root features to create sustainable tree plantings. As a result of the information a list was compiled and the collective knowledge of landscaping amongst the professionals was gathered into themes. These themes were then divided in to four headings: nutrition, root ball, design and soil conditions. In addition, all of the interviewees agreed that the most important thing for tree planting is to select the right tree species for the right soil. / SAMMANFATTNING Syftet med den här intervjustudien är att ta reda på en grupp yrkesverksammas samlade kunskap om rotsystemens olika egenskaper hos träd och sedan utforska hur de yrkesverksamma anpassar anlagda gröna miljöer till trädens rotegenskaper på ett hållbart sätt. Fem personer som arbetar med trädplantering intervjuades för att besvara studiens tre frågeställningar om rotsystemen hos träd. De två första frågeställningarna gällde: Vilka träd har särskilda rotegenskaper att ta hänsyn till och vilka anpassningar i anläggandet gör yrkesverksamma för de respektive trädens rotsystem? Utifrån intervjusvaren sammanställdes en lista där 22 träd med särskilda rotegenskaper presenteras tillsammans med vilken typ av anpassning de yrkesverksamma rekommenderar. Den tredje och sista frågeställningen var; Hur arbetar de yrkesverksamma generellt med rotsystem hos träd i anläggningar för att skapa hållbara gröna miljöer? Frågeställningen utmynnade i fyra huvudområden som beskriver hur de yrkesverksamma arbetar med näring, rotklump, design och mark för att skapa hållbara gröna miljöer. Slutligen svarade fyra av de fem informanterna att de inte hade rotsystemet i tanke när de valde träd till en plats. Trots det tog alla hänsyn till egenskaper som t.ex. blöt mark, lerjord, sandjord och urban miljö när de valde träd till en plats. Därutöver var alla var överrens om att artvalet är viktigt när träd ska planteras i en anläggning, dvs. rätt träd på rätt jord.

Doctor of Philosophy(PhD) / It is generally accepted that tree roots can reinforce soil and improve the stability of vegetated slopes. Tree root reinforcement is also recognised in riverbanks although the contribution that the roots make to bank stability has rarely been assessed due to the reluctance of geomorphologists to examine riverbank stability by geomechanical methods that allow for the inclusion of quantified biotechnical parameters. This study investigates the interaction between alluvial soil and the roots of four southeastern Australian riparian trees. It quantifies the amount and distribution of root reinforcement present beneath typically vegetated riverbanks of the upper Nepean River, New South Wales, and examines the effect of the reinforcement on the stability of these banks. The ability of a tree to reinforce the soil is limited by the spatial distribution of its root system and the strength that the roots impart to the soil during shear. These two parameters were determined for the following four species of native riparian tree: Casuarina glauca, Eucalyptus amplifolia, Eucalyptus elata, and Acacia floribunda. The four species all exhibit a progressive reduction in the quantity of root material both with increasing depth and with increasing lateral distance from the tree stem. In the vertical direction there are two distinct zones that can be described. The first occurs from between 0 and approximately 15 % of the maximum vertical depth and consists of approximately 80 % of the total root material quantity. In this zone the root system consists of both vertical and lateral roots, the size and density of which varies between species. The second zone occurs below approximately 15 % of the maximum vertical depth and consists primarily of vertical roots. The quantity of root material in this zone decreases exponentially with depth due to the taper of individual roots. The earth reinforcement potential in terms of both geometric extent and the quantity of root material expressed as the Root Area Ratio (RAR) varies significantly from species to species. E. elata exhibited the highest values of RAR in soil zones beneath it while E. amplifolia reinforced a greater volume of soil than any of the other species examined. The increased shear resistance (Sr) of alluvial soil containing roots was measured by direct in-situ shear tests on soil blocks beneath a plantation. For three of the species (C. glauca, E. amplifolia, E. elata) Sr increased with increasing RAR measured at the shear plane, in a similar linear relationship. The shear resistance provided by A. floribunda roots also increased with increasing RAR at the shear plane but at a much greater rate than for the other three species. This is attributable to A. floribunda’s greater root tensile strength and therefore pull-out resistance, as well as its smaller root diameters at comparative RARs which resulted in a greater proportion of roots reaching full tensile strength within the confines of the test. Tree roots fail progressively in this system. Therefore determining the increased shear strength from the sum of the pull-out or tensile strengths of all individual roots and Waldron’s (1977) and Wu et al’s (1979) simple root model, would result in substantial over estimates of the overall strength of the soil-root system. The average difference between Sr calculated in this manner and that measured from direct in-situ shear tests is 10.9 kPa for C. glauca, 19.0 kPa for E. amplifolia, 19.3 kPa for E. elata, and 8.8 kPa for A. floribunda. A riverbank stability analysis incorporating the root reinforcement effect was conducted using a predictive model of the spatial distribution of root reinforcement beneath riparian trees within the study area. The model is based on measurements of juveniles and observations of the rooting habits of mature trees. It indicates that while the presence of vegetation on riverbank profiles has the potential to increase stability by up to 105 %, the relative increase depends heavily on the actual vegetation type, density, and location on the bank profile. Of the species examined in this study the greatest potential for improved riverbank stability is provided by E. amplifolia, followed by E. elata, A. floribunda, and C. glauca. The presence of trees on banks of the Nepean River has the potential to raise the critical factor of safety (FoS) from a value that is very unstable (0.85) to significantly above 1.00 even when the banks are completely saturated and subject to rapid draw-down. It is likely then that the period of intense bank instability observed within this environment between 1947 and 1992 would not have taken place had the riparian vegetation not been cleared prior to the onset of wetter climatic conditions. Typical ‘present-day’ profiles are critically to marginally stable. The introduction of vegetation could improve stability by raising the FoS up to 1.68 however the selection of revegetation species is crucial. With the placement of a large growing Eucalypt at a suitable spacing (around 3-5 m) the choice of smaller understorey trees and shrubs is less important. The effect of riparian vegetation on bank stability has important implications for channel morphological change. This study quantifies the mechanical earth reinforcing effect of some native riparian trees, thus allowing for improved deterministic assessment of historical channel change and an improved basis for future riverine management.