Orientador: Everlon Cid Rigobelo / Banca: Osania Emerenciano Ferreira / Banca: Fábio Camilotti / Resumo: Bactérias promotoras do crescimento de plantas podem promover aumento na biometria vegetal, na absorção de nutrientes e sua atuação pode ser incrementada pela disponibilização de carbono e energia, fornecidos via adubação. Desta forma, o experimento foi conduzido com o objetivo de avaliar o efeito dos Bacillus subtilis e Bacillus pumilus em mudas pré-brotadas (MPB) de cana-de-açúcar e ação das mesmas bactérias associadas à adubação com vinhaça, torta de filtro e o composto de torta de filtro no cultivo inicial de cana-de- açúcar em vasos ao ar livre. O experimento foi dividido em duas fases. Na fase 1 foram utilizadas MPB e os tratamentos constituídos por: T1= Sem inóculo, T2= B. subtilis, T3= B. pumilus e T4= B. subtilis + B. pumilus, realizado em delineamento em blocos ao acaso, com quatro repetições. No final do período de formação das MPB que foi de 60 dias, foram aferidas as massas seca de parte aérea, de raízes e total e ainda feita contagem do número de bactérias totais no substrato. Na fase 2, os fatores em estudo foram quatro inoculações, sendo T1= Sem inóculo, T2= B. subtilis, T3= B. pumilus e T4= B. subtilis + B. pumilus com quatro tipos de adubações: A1= Adubação mineral (AM), A2= AM + vinhaça, A3= AM + torta de filtro e A4= AM + composto de torta de filtro, combinados em esquema fatorial 4x4, com quatro repetições. Os parâmetros avaliados foram: dados biométricos das plantas, massa seca de parte aérea, raízes e total, contagem do número de bactérias totais, fósfo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Plant growth rhizobacteria might promote an increase of biometric plant and their action can be optimized by availability of carbon and energy, provided via organic fertilization. In this way, the experiment was carried out with aim to evaluate the fertilization effect with cane's wastes and promoted bacteria inoculation at initial seedling of sugar cane. The experiment was divided at two phases. Phase 1 were utilized Pre-Sprouted-Seedlings (PSS) and the treatments were T1 = control, T2 = Bacillus subtilis, T3 = B. pumilus and T4 = B. subtilis + B. pumilus. The design was randomized blocks with four repetitions. At the final period of PSS formation, were measured the shoot, root and total dry matter and also total bacteria of substrate. At the phase II the factors analysed were four kind of inoculations being T1= no inoculum, T2= B. subtilis, T3= B. pumilus and T4= B. subtilis + B. pumilus with four kind of fertilizations: F1= mineral fertilization (MF), F2= MF + vinasse, F3= MF + filter cake and F4= MF + filter cake compost, combined with 4 x 4 factorial scheme, with four repetitions. The evaluated parameters were: plants biometric data, shoot, root and total dry matter, total bacteria counting, soluble phosphorus, ammonium and nitrate levels into soil. At the PSS phase the use of bacteria promoted the increasing of root and total dry matter. At the phase 2 the treatments which received inoculas had higher height and plant's diameter and also higher root and total dry matter, with emphasis on B. pumilus, which provided greater. Treatments that serve vineyard associated with mineral fertilization have hampered the development of plants with lower biometric data and lower dry mass of all parts of the plant, while not increasing the size of a number of total bactéria. At the soil analysis, it was observed, that the addition of bacteria promoted a (Complete abstract click electronic access below) / Mestre

No description available.

In tropical regions, climate change is predicted to lead to increased drought frequency and intensity. The extent to which this will shift the functional diversity of tropical tree communities is unknown due to a limited understanding about the response of seedlings to variable soil moisture. We addressed this issue using an experimental approach in the Luquillo Experimental Forest, Puerto Rico. We exposed seedlings of eight tree species, representing different successional stages, to an experimental soil moisture gradient. We evaluated (1) How species mean trait values relate to species-specific demographic responses to drought, (2) How intraspecific variation in functional traits relates to a soil moisture gradient, (3) The extent to which demographic response to short-term experimental drought mirrored long-term demographic response of seedlings to natural variation in soil moisture. Growth and survival of species with more `conservative` functional strategies tended to be more sensitive to a change in soil moisture and more tolerant to drought compared to species with more `acquisitive` strategies. In addition, traits of individual seedlings within species varied with respect to soil moisture, suggesting a potential role for phenotypic plasticity in response to drought. Specifically, this response was significant for three species (Inga laurina, Guarea guidonia, Schefflera morototoni) and was primarily associated with relative carbon investment in leaves and roots. Species demographic responses to soil moisture in experimental and long-term studies were weakly positively correlated but more variables are at play under natural conditions, which partly decouples these responses. Overall, our results suggest that tree species with `conservative` functional strategies are likely to become more common under increasing drought frequency and intensity in the Luquillo Mountains of Puerto Rico. However, understanding the broader implications of our findings will require considering the effects of other disturbances, including hurricanes, which may have contrasting effects. Furthermore, intraspecific variation in functional traits is likely to influence how the seedlings of tropical tree species cope with drought.

Lettuce (Lactuca sativa L.) seedlings diseases caused by soilborne pathogens are characterised by root rot, stem rot and damping-off of the seedlings that can occur at any time during growth. Fusarium solani, Pythium ultimum and Rhizoctonia solani are known to be the important destructive pathogens of lettuce, causing severe yield losses in South Africa. The aim of this research was to evaluate the effects of three selected fungicides to control these pathogens on lettuce seedlings. In this study the fungicides metalaxyl (Apron®), fludioxonil (Celest®) and mefenoxam (Subdue®) were applied at two concentrations as single and double doses on lettuce seedlings to determine their efficacy to control the pathogens Fusarium solani, Pythium ultimum and Rhizoctonia solani after significant reduction of mycelia growth was observed in vitro. Cultures of P. ultimum (UPGH024), R. solani (UPGH122) and F. solani (UPGH122) were obtained from the culture collection of the Department of Microbiology and Plant Pathology, University of Pretoria and cultivated on PDA for 2 days at 25ºC. Pasteurised soil was artificially inoculated with these pathogens. For the first experiment lettuce seeds were planted in polystyrene seedling trays at a depth of 1.0 cm. There were four replications of 50 seeds per treatment. In Experiment 2 pots (12 cm x 7 cm) were filled with pasteurised growing medium and 3-week old seedlings were transplanted. There were three replications of six pots containing three plants each. Seedling trays and pots were drenched with fungicides and placed in a randomised block design in a controlled environment room at 20- 26°C with a 12h-light/dark regime. The seedling trays and pots were rotated daily in the room. Seedling trays and pots were watered daily to maintain field capacity. The seedlings were able to grow larger in the pots than in seedling trays. It was confirmed that the treatment with fludioxonil (Celest®) at double and single dose inhibited the growth of the three fungi F. solani, P. ultimum and R. solani on lettuce seedlings without causing phytotoxicity. All three fungicides significantly reduced the diseases caused by the three pathogens. These findings are consistent with previous reports that fludioxonil, metalaxyl and mefenoxam can control oomycete fungi. There are few registered fungicides for the control of Fusarium solani, Pythium ultimum and Rhizoctonia solani on lettuce, therefore further work will aim to confirm these results in the field. / Dissertation (MInstAgrar)--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

Seeds of oat, green foxtail, squash and tomato were germinated in soil treated with different levels of DCPA (dimethyl 2, 3, 5, 6-tetrachlorote-rephthalate). The concentrations used varied according to the sensitivity of the plants to the chemical. The response of oat and foxtail to DCPA was similar. The growth of booth root and shoot was reduced. This reduction was directly related to the concentration of DCPA. Anatomical studies showed that cells in the shoot and root meristems of treated plants were completely disarranged and that some of the cells of these regions were hypertrophied. Some clumping of nuclei was observed in oat shoot tip. Foxtail showed a stimulation of shoot growth at 2 ppm level of DCPA. In both grass species differentiation seemed to start nearer the apex in treated plants and was highly irregular. Histochemical tests showed that the amount of starch, proteins and nucleic acids decreased with an increase of DCPA concentration. The walls of shoot meristem cells were thickened. The size and number of chloroplasts were increased in the cells of first true leaves. Seeds of treated plants seemed to contain more starch and protein. In squash, even though the shoot and root growth was reduced, no anatomical or histochemical differences could be observed except that the amount of starch in shoot meristems was slightly increased with increased concentrations of DCPA and that cotyledons of treated plants contained more starch and protein. These cotyledons also contained more and larger chloroplasts. The cytogenetical studies failed to show any differences in the mitotic index of plants studied. No abnormal chromosome behavior was observed.

No description available.

Three factors were tested in an attempt to accelerate the growth of Abies fraseri seedlings grown in containers in a greenhouse: growth medium acidity. foliar application of growth regulators. and supply of nitrogen fertilizer. Sphagnum peat growth medium was adjusted with a to 8 kg dolomitic limestone/m3 compressed packaged peat to initial pH ranging from 3.9 to 6.7. Best growth (21.2 cm mean height at 19 months) was achieved with 1 kg/m³ and 2 kg/m³â ¢ with initial mean pH 4.2 and 4.5. respectively. Seedlings with 4 and 8 kg/m³ grew more slowly (17.4 and 9.5 cm. respectively. in 19 months). and many were chlorotic. with poor root development. Three growth regulators were sprayed on seedlings: benzylaminopurine (BAP). gibberellic acid (G~. and indolebutyric acid (IBA). BAP stimulated terminal bud activity. decreasing the periods of rest between active growth. BAP increased height and diameter of new shoot growth up to 19% and 32% respectively. BAP reduced root growth 22% when applied at the higher concentration (100 ppm). GA3 had no main effect on either shoot or root growth. However. GA3 did increase shoot growth slightly in the absence of BAP. IBA increased root growth up to 26%. IBA had no significant effect on shoot growth. Nitrogen fertilizer was supplied weekly in concentrations of 200. 400. and 600 ppm. At six months age there was no treatment effect on seedling growth. At nine months age 400 ppm N had produced 9% more shoot growth than either 200 or 600 ppm N. Nine-month-old seedlings with 400 ppm fertilizer averaged 8.9 cm in height. / Master of Science

Tris-soluble protein and total nitrogen of tall and dwarf tomato (Lycopersicon esculentum Mill.) seedlings were determined by the method of Lowry et al. and a modified micro-Kjeldahl direct Nesslerization technique. The tall tomato 'Fireball' differs from the dwarf 'Md. 412-4' in several ways: (1) the tall has more total nitrogen and protein; (2) it exhibits a significant increase in protein during the initial 48-hours of seeds imbibition; (3) it has a higher amount of protein in the roots; (4) the rate of decline of total nitrogen is faster than the dwarf, and (5) the tall tomato is more efficient in the utilization of plant nitrogen and protein. The greater growth of the tall resulted in a more rapid decline in nitrogen. However, in 10-18 day-old seedlings, growth was still rapid while nitrogen and protein did not change appreciably. The tall was more efficient and utilized a lesser amount of nitrogen and protein in the production of a comparable amount of fresh weight. It is suggested that the roots have considerable influence(s) on the growth of the shoot and that the decline in nitrogen and protein is a resultant of growth. It is indicated that the differences in growth may be more dependent on the manner in which nitrogen and protein are utilized rather than their absolute content. / Master of Science

The potential for using large scale, small format aerial photography to obtain seedling density and woody competition information was investigated. Factors affecting photo interpretation of seedlings were examined and equations to predict seedling density and woody competition levels were developed and evaluated. Two scales of imagery, 1:4000 and 1:6000 were considered to compare their relative merits for these purposes. Greater age of the seedlings and their inherent development generally served to improve photo interpretation. The amount of woody competition present in the plots tended to hinder seedling identification at the 1:4000 scale, while enhancing it when 1:6000 scale data was used. Seedling density estimation and evaluation of competition through Free-To-Grow classification predictions yielded results comparable to ground surveys. Estimation of total groundline basal area in all woody competition, and classification of the plots by the amount of hard-to-control competition they contained, were less successful. These results may have been due in part to the partial leaf fall that occurred prior to obtaining the imagery. Many of the results found in this study favored the larger scale (1:4000) imagery, and its use for the procedures described is recommended. / M.S.

Effects of fungi and overstory composition on tree seedling survival and growth were investigated in closed canopy upland forests in the coastal plain of South Carolina. Seedlings of Quercus alba, Cornus florida and Pinus taeda were planted in the understory of two forest types -naturally regenerated hardwood and planted pine. Fungal species composition and biomass were experimentally manipulated with a treatment of the fungicide captan. In contrast with other studies conducted in different systems (sand dune, grassland, and old field), the effects of soil fungi were minor in a closed canopy forest. Only Q. alba showed a significant response to the fungicide (p < 0.05) treatment with increased growth. Overstory composition had no significant effect on growth or survival for any of the species. Both of the commercially desirable species (Q. alba and P. taeda) had reasonable survival ( @ 60%). Both also maintained positive, though modest, growth. This suggests that an advance regeneration pool could be established successfully by artificial regeneration. / Master of Science