Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Parapiptadenia rigida (mimosa-red) and Luehea divaricata (horse-whips) are native species that are widely distributed throughout Brazil, indicated for restoration of areas that are being recovered and permanent preservation areas. These species have been over-exploited, and yet, still lack of studies related to its conservation and perpetuation. The present study aimed to evaluate the effects of irrigation on the survival and growth of Parapiptadenia rigida and Luehea divaricata seedlings on different substrate types in the nursery. The study was conducted at Forest Nursery, Department of Forest Sciences, Federal University of Santa Maria (UFSM). The fruits of Parapiptadenia rigida were collected in September 2009 in the region of Santa Maria (RS) of 28 trees, and the fruits mature of Luehea divaricata were collected in July 2010 at the Morro Cerrito, Santa Maria, in eight trees matrices. After processing, seeds were stored for later sowing. The sowing of horse-whips and mimosa-red were held on November 22 and December 10, 2010, respectively. For both species, we used a randomized block design with four replications, consisting of factorial scheme, considering six irrigation levels (4, 8, 12, 16, 20 and 24 mm.day-1) and 4 formulations substrates ( 100T: 100% peat 80T: 80% peat and 20% rice hulls; 60T: 60% peat and 40% rice hulls; 40T: 40% peat and 60% rice hulls), whose variables height, diameter, and ratio H/DC were evaluated in time to produce a factorial, and variable survival, dry matter production, leaf area and Dickson Quality Index (IQD), were evaluated only at the last measurement (two-factor). The results allow us to conclude that the 184 days after sowing, the survival of Parapiptadenia rigida and Luehea divaricata were, respectively, 100% and above 93%. Moreover, for the mimosa-red, the blade of 4 mm.day-1 together with the substrate composed of 80% peat and 20% rice hulls gave the best seedling development. For the horse-whips, the blade of 16 mm.day-1 in combination with the substrate composed of 100% peat, provided the best seedling development. Thus, it is recommended daily blades of 4 mm.day-1 and 16 mm.day-1 and substrates 80T and 100T, and to Parapiptadenia rigida Luehea divaricata, respectively, as being ideal for the growth of both species in nurseries . / Parapiptadenia rigida (angico-vermelho) e Luehea divaricata (açoita-cavalo) são espécies nativas que apresentam ampla distribuição pelo território brasileiro, indicadas para recomposição de áreas que estão sendo recuperadas e áreas de preservação permanente. Essas espécies foram excessivamente exploradas, e apesar disso, ainda carecem de estudos relacionados a sua conservação e perpetuação. O presente estudo teve como objetivos avaliar os efeitos das lâminas de irrigação na sobrevivência e crescimento de mudas de Parapiptadenia rigida e Luehea divaricata em diferentes formulações de substrato em viveiro. O trabalho foi desenvolvido no Viveiro Florestal, do Departamento de Ciências Florestais da Universidade Federal de Santa Maria (UFSM). Os frutos de Parapiptadenia rigida foram coletados em setembro de 2009, na região de Santa Maria (RS), de 28 árvores, e os frutos maduros de Luehea divaricata foram coletados em julho de 2010, no Morro do Cerrito, Santa Maria, em oito árvores matrizes. Após o beneficiamento, as sementes foram armazenadas para posterior semeio. A semeadura de açoita-cavalo e angico-vermelho foi realizada nos dias 22 de novembro e 10 de dezembro de 2010, respectivamente. Para ambas as espécies foram utilizadas delineamento em blocos casualizados, com 4 repetições, constituído de esquema fatorial, considerando 6 lâminas de irrigação (4, 8, 12, 16, 20 e 24 mm.dia-1) e 4 formulações de substratos (100T: 100% turfa; 80T: 80% turfa e 20% casca de arroz carbonizada; 60T: 60% turfa e 40% casca de arroz carbonizada; 40T: 40% turfa e 60% casca de arroz carbonizada), cujas variáveis altura, diâmetro do coleto, e relação h/d foram avaliadas no tempo, constituindo um trifatorial, e a variável sobrevivência, produção de massa seca, área foliar e Índice de Qualidade de Dickson (IQD), foram avaliados somente na última medição (bifatorial). Os resultados obtidos permitem inferir que, aos 184 dias após a semeadura, a sobrevivência de Parapiptadenia rigida e Luehea divaricata foram, respectivamente, 100% e acima de 93%. Além disso, para o angico-vermelho, a lâmina de 4 mm.dia-1 juntamente com o substrato composto por 80% Turfa e 20% casca de arroz carbonizada proporcionaram o melhor desenvolvimento das mudas. Para a açoita-cavalo, a lâmina de 16 mm.dia-1 em combinação com o substrato composto por 100% turfa, proporcionaram o melhor desenvolvimento das mudas. Assim, recomendam-se as lâminas diárias de 4 mm.dia-1 e 16 mm.dia-1 e os substratos 80T e 100T, para Parapiptadenia rigida e Luehea divaricata, respectivamente, como sendo ideais para o crescimento de ambas as espécies em viveiro.

With the increase of the demand for forest seedlings, both training for business stands and recovery of degraded areas, there is a growing concern with the reduction of costs and the need to follow sustainability standards in the production of seedlings. For this reason, renewable materials have been studied and used for formulation of substrates, and the lump of peach has potential to be used with this purpose, which has the physical structure rigid that do not decomposes with ease and, when triturated, retains particles of various granulometries. The present study had as objectives: I - Evaluate the characteristics peach lump triturated for use as a component of the substrate for plants; II - to investigate the influence of substrates with different proportions of peach lump triturated seedling growth of E. dunnii seeds in the nursery and the performance in the field. Were used different proportions of mixture [100:0%, 80:20%; 60:40%; 40:60%; 20:80%; 0:100% (volume:volume)] from peach lump triturated (C) and commercial substrate (S), composing the group 1 (CxS), and C and peat brown (T), called the group 2 (CxT). It was evaluated the physical, chemical and the content of the macronutrients of mixtures. In the nursery evaluations were made of height (H), collar diameter (DC), H/DC, dry mass carrier, root dry mass, total dry mass, the quality index of Dickson, leaf area, root length and volume, ease of withdrawal of the seedlings in the polyethylene tube, aggregation of roots and photochemical efficiency of photosystem II maximum In the field, it was evaluated the survival, the increment in the growth in height and diameter of the stem base diameters and physiological variables during 240 days. In general, the results obtained allow us to infer that the peach lump triturated presents physical and chemical characteristics suitable for use as a component of substrates, increasing the density wet and dry, the material consisting of aeration and pH, while the total porosity, water holding capacity and the electric conductivity had lower values for the substrates with or with a higher proportion of peach lump triturated. In the production of seedlings of E. dunnii seeds, this material reduced the growth of the same, but can be used as a component of substrate in all the proportions of the mixture with commercial substrate without interfering with their development in the field, but with proportions greater than 20% change has difficulty be removed from the cartridge and less aggregation, reducing the yield of the operations in the field. Mixed with brown peat, it is recommended to use proportions between 15% and 30% of crushed peach kernel allowing better growth of seedlings in the nursery and good performance after planting. / Com o aumento da demanda por mudas florestais, tanto para formação de povoamentos comerciais quanto para recuperação de áreas degradadas, houve uma consequente preocupação com a redução dos custos e necessidade de seguir padrões de sustentabilidade na produção de mudas. Para isso, materiais renováveis vêm sendo pesquisados e utilizados para formulação de substratos e o caroço de pêssego possui potencial para ser utilizado com essa finalidade, o qual possui estrutura física rígida que não se decompõe com facilidade e, quando triturado, mantem partículas de diversas granulometrias. O presente estudo teve como objetivos: I Avaliar as características do caroço de pêssego triturado para uso como componente de substrato para plantas; II Investigar a influência de substratos com diferentes proporções de caroço de pêssego triturado no crescimento de mudas de Eucalyptus dunnii no viveiro e o desempenho em campo. Foram utilizadas diferentes proporções de mistura [100:0%, 80:20%; 60:40%; 40:60%; 20:80%; 0:100% (volume:volume)] de caroço de pêssego triturado (C) com substrato comercial a base de composto orgânico (S), compondo o grupo 1 (CxS), e C com turfa marrom (T), denominado grupo 2 (CxT). Avaliaram-se as propriedades físicas, químicas e o teor de macronutrientes das misturas. No viveiro foram realizadas avaliações da altura (H), diâmetro do coleto (DC), relação H/DC, massa seca aérea, massa seca radicular, massa seca total, índice de qualidade de Dickson, área foliar, comprimento e volume radicular, facilidade de retirada das mudas do tubete, agregação das raízes e eficiência fotoquímica máxima do fotossistema II. No campo, avaliou-se a sobrevivência, o incremento no crescimento em altura e em diâmetro do coleto e variáveis fisiológicas durante 240 dias. De maneira geral, os resultados obtidos permitem inferir que o caroço de pêssego triturado apresenta características físicas e químicas adequadas para uso como componente de substratos. Esse material aumenta a densidade úmida e seca, o espaço de aeração e pH, enquanto que reduz a porosidade total, a capacidade de retenção de água e a condutividade elétrica. Na produção de mudas de E. dunnii, esse material reduziu o crescimento das mesmas, mas pode ser utilizado como componente de substrato em todas as proporções de mistura com substrato comercial a base de composto orgânico sem interferir no seu desenvolvimento a campo, porém com proporções superiores a 20% a muda apresenta dificuldade de ser retirada do tubete e menor agregação, reduzindo o rendimento das operações no campo. Em mistura com turfa marrom, recomenda-se utilizar proporções entre 15% e 30% de caroço de pêssego triturado permitindo melhor crescimento das mudas no viveiro e bom desempenho após o plantio.

Coffea arabica var. Laurina (Bourbon pointu, BP) est un mutant naturel de C. arabica ‘Bourbon’ (B). La mutation laurina est récessive, monolocus, Mendélienne et ses effets pléiotropiques. Ces effets ont été étudiés sur le développement des graines et chez les plantules en histologie, morphologie et biochimie. La standardisation de la croissance en taille des graines était primordiale, notamment pour l'étude fine de la composition en polysaccharides pariétaux (PP). Les stades (st) de développement ont été reliés à l'âge des fruits et leur aspect histo-morphologique (st 1-2, 3, 4 : croissance ; st 5 à 7 : maturation). L'étude de la composition en PP a mis en évidence trois phases : φ 1 (st 1-2, 3), φ 2 (st 3, 4, première partie du 5), et φ 3 (deuxième partie du 5, st 6 et 7). La mutation affecte les φ 1 et 2, probablement par le biais du périsperme. Chez la plantule, la mutation affecte la longueur des hypocotyles exposés à la lumière en provoquant le semi-nanisme de BP par rapport à B par un nombre moindre de cellules. Les teneurs en ABA, auxine et cytokinines sont aussi touchées. La composition en PP et en acides chlorogéniques (CQA) n'est affectée ni par la mutation, ni par la lumière pendant la croissance des plantules (sauf pour les CQA ses racines). Un effet-organe est mis en évidence. La mutation réduit la teneur en caféine (CAF) et la différence variétale est présente à la lumière et à l'obscurité. Ces résultats permettent de mieux caractériser les effets pléiotropiques de la mutation laurina. Ils permettent une meilleure 1/ compréhension de l'évolution des PP de la graine au cours de son développement et 2/ connaissance des hormones, CAF, CQA et PP des plantules. / Coffea arabica var Laurina (Bourbon pointu, BP), is a natural mutant of C. arabica ‘Bourbon’ (B). The laurina mutation is recessive, monolocus and Mendelian, with pleiotropic effects. This work highlighted new effects of this mutation, with histological, morphological and biochemical approaches on seeds development and on seedlings. Simultaneous fitting of growth curves of B and BP and their standardization allow comparisons of these varieties and fine study of polysaccharide cell wall (PCW) composition over time. Thus, anatomic specificities, development stages (st) and fruit age were linked (growth: st 1-2 to 4; maturation: st 5 to 7). When taking in account the CWP evolution in time-course, three phases occurred: φ 1 (st 1-2, 3), φ 2 (st 3, 4 and the beginning of 5), and φ 3 (the end of 5, st 6, 7). The two first were affected by the mutation probably through maternal effect (perisperm). In seedlings, the hypocotyls semi-dwarfism in light growth condition is an effect of the mutation and was due to a lower cell number than in B. The phytohormones content was also affected (ABA, auxine, cytokinins). But, neither CWP composition nor chlorogenics acids (CQA) content were affected by the mutation, or growth condition (expected for CQA content in roots). The composition in CWP and CQA was different depending on organs. Finally, caffeine (CAF) content was affected by the mutation in light or darkness conditions. These results represent an important step in 1/ the characterization of the pleiotropic effects of the laurina mutation, 2/ the understanding of the CWP evolution in seed time course, and 3/ new knowledge on seedlings (hormone, CAF, CQA and CWP composition).

Au cours de ce travail nous avons utilisé les potentialités de différentes modalités d'imagerie, que nous appliquons au domaine du végétal afin de contribuer au phénotypage haut-débit des semences et plantules. Nous nous somme principalement consacré à la recherche de réponses à deux problématiques spécifiques et importantes de ce secteur. Nous commençons par montrer l'applicabilité de l'imagerie en lumière visible inactinique et de l'imagerie thermographique passive pour imager le développement des semences et plantules, un phénomène biologique se déroulant normalement dans le sol et l’obscurité. Nous présentons nos apports à ce type d’imagerie, au travers de nos contributions à la conception et à la réalisation d’un système de vision en imagerie visible inactinique, ayant pour finalité la réalisation de mesures individualisées automatisées sur les semences, les plantules et les organes des plantules. Ce système gère les croisements de plantules, via l'utilisation originale de la diffusion anisotrope, ce qui nous a permis de multiplier, sans perte d'information, les débits par dix. De plus, ce système réalise la séparation des organes au moyen d’un critère générique basé sur le gravitropisme. La validation des algorithmes de traitement d'images du système de vision utilise des voies originales (simulation numérique et test de l'influence de l'incertitude via simulation agronomique). L’imagerie thermographique, qui capte le rayonnement thermique passif des objets, nous permet de visualiser et de mesurer les semences et plantules dans l'obscurité. Elle permet aussi de réaliser la segmentation et le suivi des organes de plantules. Cette technologie d'imagerie nous a aussi permis de montrer la faisabilité d'un dosage non destructif de teneur en sucre des organes de plantules de betterave. Ensuite nous proposons une méthodologie générique permettant la conception de capteurs bas-coût spectralement optimisés, en fonction de tâches applicatives déterminées. Cette méthodologie utilise la théorie de l’information, pour extraire de l’imagerie hyperspectrale, relativement coûteuse, l’information utile à la conception des capteurs dédiés bas-coût. L’intérêt de cette méthodologie pour le phénotypage des plantes est montré et justifie le transfert de celle-ci au monde de la recherche en biologie végétale. / Along this work, we have used the potentiality of different modalities of imagery that we apply to the plant domain so as to contribute to the high-throughput phenotyping of seeds and seedlings. We have mainly committed ourselves to the search for answers to two specific and important problematic in this domain. We begin by showing the applicability of visible imaging using an inactinic light and passive thermographic imaging to image the development of seeds and seedlings, a biological phenomenon usually occurring in soil and darkness. We present our contributions to this type of imaging through our contributions to the conception and the realization of a vision system using visible inactinic imaging, whose finality is the realization of individualized automated measurement on the seeds, the seedlings and the organs of the seedlings. This system handle seedling crossing, through the original use of anisotropic diffusion, which allowed us to multiply, without information loss, the output by ten. Furthermore, this system carries out the separation of the organs by means of a generic criterion based on gravitropism. The validation of the image processing algorithms of the vision system use original ways (numerical simulation and test of the influence of the uncertainty through agronomic simulation). Thermographic imaging, which captures the passive heat radiation of objects, allows us to visualize and to measure seeds and seedlings in the darkness. It also allows realizing the segmentation and the tracking of the organs of seedlings. This imaging technology also allowed us to demonstrate the feasibility of a non-destructive determination of sugar quantity in organs of beet seedlings. We then propose a generic methodology that allows the conception of spectrally optimized low-cost sensors, according to determined application tasks. This methodology uses information theory, to extract from, relatively expensive, hyperspectral imaging, the information needed for the conception of the dedicated low-cost sensors. The interest of this methodology for plant phenotyping has been shown and justifies its transfer to the world of research in plant biology.

Breeding maize (Zea mays L.) for tolerance to acidic soils could improve maize yields. The current study aims to identify maize genotypes with tolerance to acidic soils, as well as identifying secondary traits associated with the tolerance to soil acidity. Ten maize varieties were screened for tolerance to aluminium (Al) toxicity under glasshouse, laboratory and field conditions. In the glasshouse, two soil acidity levels (limed and unlimed soil) were used and the experiment was set up in a complete randomised design (CRD) with three replications. The experiment lasted for 10 days and measurements were taken on plant height (PH), leaf area, stem diameter and dry matter. In the laboratory, a haematoxylin staining (HS) experiment was conducted to determine the response of 10 maize varieties to Al toxicity. Two Al concentrations (0 and 222 μM) were used and the experiment was set up in a completely randomized design with three replications. After 7 days, shoot length, was recorded. Five stress tolerance indices were estimated to determine the resilience of each genotype. A root growth stress tolerance index was also computed for both experimental procedures. In the field, two trials were established at two sites, namely Mbinja and Mpumaze. Limed and unlimed plots were used, and the trial was set up in a randomized complete block design with three replications. Maize kernel yield and other standard field parameters were recorded. Selection of tolerant genotypes from the field screening was also done using three indices, namely harmonic mean (HM), stress tolerance index (STI) and stress susceptibility index (SSI). Both the glasshouse and laboratory assays identified similar genotypes of maize as being tolerant. These tolerant genotypes were Ngoyi, PANBG3492 BT, PAN 6Q408 and PHB 3442 based on the root growth stress tolerance index (RGSTI). It was therefore demonstrated that these two assays produced the same level of efficiency in identifying tolerant genotypes using this index. Based on ranking of seedling vigour index under soil acidity stress, the top three genotypes at Mpumaze were PHB32W71, PAN6616 and Sahara while at Mbinja, the top three were PAN6616, PAN6Q408 CB and PAN6P110. The genotypes PANBG3492 BT, PAN6Q408 and PHB3442 were also found to be tolerant to acidic soils at seedling stage. These genotypes are recommended for further evaluation in more sites to confirm their tolerance and yield potential under acidic soils. The study also revealed that plant height, leaf area and stem diameter could be used for indirect selection for tolerance to Al toxicity under glasshouse conditions. The seedling vigour index was also effective in identifying tolerant genotypes under glasshouse conditions. On the other hand, shoot length stress tolerance index and the haematoxylin score were useful for indirect selection for tolerance to Al toxicity in the laboratory. In the field, it was observed that ear length, leaf area and ear diameter can be useful in identifying genotypes that are tolerant to soil acidity. They can therefore be useful as indirect selection criteria under field conditions. Additionally, the best selection indices for identifying soil acidity tolerant genotypes under field conditions were the HM and the STI. It is recommended that varieties that were identified as tolerant be further evaluated in several soil acidity hot spots to confirm their tolerance and stability of performance under field conditions. / Agriculture and  Animal Health / M. Sc. (Agriculture)

As communities and managers become aware of the long-term impacts of mangrove loss, estimated at 1-2% per year, interest in sediment erosion and mangrove rehabilitation has increased substantially. In this thesis project I 1) examine erosion rates within coastal fringing Rhizophora mangle ecosystems following mangrove clearing and compare these rates to accretion rates in intact mangroves; and 2) investigate the abiotic factors influencing mangrove seedling survival and regeneration of naturally colonizing R. mangle, in historic mangrove habitat after anthropogenic clearing. Differences in erosion were compared between patches of open-coast intact and anthropogenically cleared R. mangle to quantify the sediment trapping function provided by mangroves and its loss following clearing over a 24 month period. Growth rates of mangrove seedlings in intact forest were compared to seedlings in cleared areas. Seedling growth indicators were measured on 100 seedlings at five sites (50 in the intact and 50 in the cleared areas). To examine the limiting factors on seedling growth rates, nutrient addition and wave protection treatments were applied to seedlings in three disturbed areas. Sites within intact mangroves had sediment accretion (M= +3.83 mm) while areas cleared of mangroves had sediment erosion (M= -7.30 mm). Seedling growth (height) over the 2 year study period significantly differed between intact mangrove (M = 15.6 cm) and cleared (M = 10.24 cm) areas. Seedling mortality from the cleared areas (31%) differed from the intact areas (13%). Average seedling growth (height) was: greater with both nutrient/wave (M = 18.4 cm) and nutrient (M = 17.65 cm) treatments compared to controls (M = 10.8 cm), which suggests that providing nutrients and/or wave protection result in growth outputs comparable to seedlings found in intact mangroves. This study may prove to be useful in identifying areas that are most vulnerable to erosion following mangrove removal and ideal location of restoration following mangrove removal. Areas cleared of mangroves can lead to intensified erosion in areas where fringing reefs are not continuous. When managers are determining areas to focus resources for restoration, focusing on areas with nutrient rich habitat may result in higher survival rates and growth outputs.

Bare-root, container, and root production method (RPM™) seedlings of two oak species (Nuttall (Quercus texana Buckley), cherrybark (Q. pagoda Ell.)) were planted on lands damaged by Hurricane Katrina in southern Mississippi to compare the height growth, groundline diameter growth and survival of the different planting stocks. Tree shelters were applied to half of the bare-root seedlings to determine their effect on the height and groundline diameter growth and survival of the seedlings. RPM seedlings exhibited significantly greater height and groundline diameter growth than bare-root or container seedlings after one growing season. Bare-root seedlings exhibited significantly greater height and groundline diameter growth than container seedlings. Tree shelters significantly increased height growth of bare-root seedlings; however, sheltered bare-root seedlings exhibited significantly less groundline diameter growth than non-sheltered seedlings. Cherrybark oak exhibited greater height growth than Nuttall oak, while Nuttall oak exhibited greater groundline diameter growth than cherrybark across all planting stocks.

Leaf area and stomata are important parameters in studies of taxonomic classification since both parameters might reflect the plant adaptation mechanisms to different environmental conditions. This study analyzed Eurycoma longifolia Jack leaf traits in different ecological regions (moisture zone: A Luoi, Bach Ma, Nam Dong; dry zone: Phong Dien) and leaves of seedlings in the nursery. The study used scanners and Images to measure leaf area; imagej and the AxioVision SE64 softwares were used to evaluate stomatal density by separating the lower cuticle through a clear nail polish impression. Our results showed that the leaf area of mature trees from the dry zone is smaller (355.7 and 484.1 cm2/leaf), however, the stomata density is higher than that of the humid area (284.4 and 137.9 stomata/mm2). Under the same nursery conditions, the seedlings' leaf area was similar while seedlings' stomatal density, originated from the dry zone, was lower. Results indicate that the stomatal density changes as an adaptation to changing habitat conditions. This study gives indicates that E. longifolia is a tree species with high adaptability given the leaf morphology changes under a changing climate. Therefore, this tree species should be a priority for planting in order to increase biodiversity in different ecological regions. / Đặc điểm diện tích lá và mật độ khí khổng là những thông số quan trọng trong các nghiên cứu phân loại học nhằm phản ánh cơ chế thích nghi của thực vật với điều kiện sống. Vì thế nghiên cứu này đã tiến hành phân tích các đặc điểm của lá cây Bách bệnh (Eurycoma longifolia Jack) từ các vùng khác nhau (A Lưới, Bạch Mã, Nam Đông: vùng ẩm và Phong Điền: vùng khô) và lá cây con của chúng ở vườn ươm. Nghiên cứu đã sử dụng máy quét và ImageJ để đo diện tích lá và phần mềm AxioVision SE64 và ImageJ để đánh giá mật độ khí khổng thông qua tách lớp biểu bì phía dưới lá qua lớp sơn mỏng Kết quả nghiên cứu cho thấy, diện tích lá của cây trưởng thành từ vùng khô nhỏ hơn (355.7 and 484.1 cm2/leaf) nhưng mật độ khí khổng lại lớn hơn so với vùng ẩm (284.4 and 137.9 stomata/mm2). Tuy nhiên, cùng điều kiện sống ở vườn ươm, diện tích lá của cây con tương tự nhau trong khi mật độ khí khổng của cây con có nguồn gốc từ vùng khô lại thấp hơn. Kết quả này chỉ ra rằng sự thay đổi của mật độ khí khổng như là một sự thích nghi với thay đổi của điều kiện môi trường sống. Từ đó nghiên cứu này cho thấy cây Bách bệnh là một loài cây gỗ với khả năng thích nghi cao nhờ sự thay đổi về đặc điểm hình thái lá khi thay đổi khí hậu cho nên loài cây này nên được ưu tiên trong việc gây trồng nhằm tăng cường tính đa dạng cho các vùng sinh thái khác nhau.

No description available.

Studies were undertaken to determine the dispersal mechanisms of Verticicladiella procera Kendrick, the causal agent of Procera Root Disease (PRD). Propagule germinability in artificially infested soil decrease rapidly under natural and controlled conditions. Colonization of seedlings in artificially infested soil was rare and symptoms were not displayed by colonized seedlings. Natural populations of V. procera were closely associated with colonized root tissue. Colonization of field planted seedlings was related to proximity to root collars of diseased trees and insect activity on the seedlings. Insects (Coleoptera) contaminated with V. procera were found in plantations both with and without PRD. The percent of weevils and bark beetles contaminated with V. procera was 64 and 0.76 respectively. Verticicladiella procera was transmitted to white pine bolts in the field and under controlled conditions following visitation by contaminated insects. Verticicladiella procera was associated with larval galleries and frass in trap bolts and was observed fruiting in insect galleries in root systems of diseased trees. This evidence suggests that transmission by insects, especially weevils, is the more important mechanism for dispersal and that soil-borne propagules have a minor role in pathogen spread. / M.S.