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Typescript (photocopy) / Digitized by Kansas Correctional Industries

Study objectives included determining whether prescribed burning affected ponderosa pine growth; mathematically modeling the growth response to burning; and determining whether forest management history affected growth response. I sampled 188 trees from two areas near Flagstaff, Arizona; one area (Brannigan Flat) had been logged and thinned, and the other (Chimney Spring) had not; both were burned in 1976. Within each study area, control and burned plots were of similar age, vigor, height, and competition index. Trees at Chimney Spring were older, less vigorous, and taller, and had a higher competition index than at Brannigan. For each tree, periodic basal area increment (PBAI) was calculated for the years 1974-1984. To determine which variable would best model growth, postfire PBAI (individual years, 1977-1984) was correlated with previous growth (average PBAI 1974-1976); crown ratio; competition index; thinning index; and diameter. Two models of growth response were developed; one oriented toward satisfying theoretical and research goals, and the other, toward management applications. Growth was modeled using stepwise multiple linear regression, and the dependent variable was postfire PBAI. Research Model independent variables were previous growth, years (climate), and treatment-year interaction, and 72% of total variance was explained. Fire affected growth significantly and negatively for two years, and then burned trees grew similarly to control trees. Management Model independent variables were crown ratio, competition index, crown ratio, subject tree diameter, year, and treatment, and 52% of total variance was explained. This model, too, indicated a slight negative effect of burning on growth. Management history was not a significant determinant of growth response. Both models validated well; the ratio of observed-to-predicted residual mean square was 1.04 and 0.91 (Research and Management Models, respectively). Thinning index was not significantly related to postfire growth, but a change in carbohydrate allocation from stem wood to crown and root expansion could have resulted in observed burning effects. Management implications include (1) short-term growth decline may result from burning, (2) management history did not affect growth response, and (3) burning impact is greatest in dense stands of small trees.

Kelpak®, a seaweed concentrate (SWC) prepared from the brown seaweed Ecklonia maxima (Osbeck) Papenfuss, improves overall plant mass and fruit yield in a variety of crops. The main active principals isolated from Kelpak® are cytokinins and auxins. Although these compounds are partly responsible for the growth promoting effect observed with Kelpak® application, they do not fully account for the complete effect of Kelpak® treatment. For this reason the focus has turned to polyamines (PAs) which are found in all cells of plants, animals and microorganisms, including eukaryotic algae. Polyamines also have growth promoting effects in plants. A study was carried out to investigate the PA levels in E. maxima and Kelpak® through a biennial cycle and to investigate if the PAs present in Kelpak® may have an effect on root growth, alleviating nutrient deficiency and the transport and accumulation of PAs in plants. To determine the amount of PA in the stipes, fronds and SWC prepared from E. maxima, samples were collected monthly over a two-year period (June 2009-June 2011). Extracts were benzoylated and quantified using a Varian HPLC. Putrescine concentrations ranged from 15.98-54.46 μg.g⁻¹, 6.01-40.46 μg.g⁻¹ and 50.66-220.49 μg.g⁻¹ DW in the stipe, fronds and SWC, respectively. Spermine concentrations ranged from 1.02-35.44 μg.g⁻¹, 1.05-26.92 μg.g⁻¹ and 7.28-118.52 μg.g⁻¹ DW in the stipe, fronds and SWC, respectively. Spermidine concentrations fell below the detection threshold. This is the first report of PAs being detected in a SWC. The seasonal pattern established for the stipe, frond and SWC followed the same trend over a biennial cycle. Polyamines accumulated in the seaweed tissue during periods of active growth and as a stress response elicited by rough wave action. This PA trend was similar to the cytokinin trend reported by MOONEY and VAN STADEN (1984b) for Sargassum heterophyllum which suggests that PAs play an important role in the hormone cascade during active growth. Routine monthly screening of Kelpak® carried out in the Research Centre for Plant Growth and Development indicated that Kelpak® consistently resulted in more rooting in the mung bean bioassay than the IBA control. The potential root promoting effect of PAs were investigated. Individually applied PAs did not increase rooting in the mung bean bioassay, but a synergistic relationship was observed between Put (10⁻³ M) and IBA (10⁻⁴ M). When applied together, rooting increased significantly above Put (10⁻³ M) and IBA (10⁻⁴ M) applied separately. The Put-auxin combination produced a similar number of roots to those treated with Kelpak®. It is possible that the PAs present in Kelpak® have a synergistic effect with auxins present in Kelpak® to promote root development and growth. Several physiological effects of Kelpak® and PAs on plant growth were investigated in a series of pot trials. Kelpak® significantly improved the growth of P- and K-deficient okra seedlings and masked the detrimental effects exerted by P- and K-deficiency. The application of PAs (10⁻⁴ M) significantly improved the seedling vigour index (SVI) of okra seedlings subjected to N-deficiency. The statistical difference was attributed to the N-containing growth regulators and polyamines being degraded and metabolized by the okra seedlings. Polyamine application did not alleviate P- and K-deficiency but increased root growth significantly in seedlings receiving an adequate supply of nutrients. It is likely that the additional PAs supported auxin-mediated root growth. A pot trial with okra plants was conducted to establish if the PAs in Kelpak®, applied as a soil drench or foliar application, are absorbed and translocated in a plant. Plants were also treated with Put, Spm, Spd to establish if PAs can be absorbed and translocated. Once the fruit had matured, plants were harvested and the endogenous PA content quantified by HPLC in the roots, stems and fruits. Applying PAs as a soil drench was not as effective as a foliar spray at increasing the PA content in the different plant parts. Kelpak® treatment (0.4%) did not contribute more PAs in any plant part. Spermidine concentrations were higher, in the various plant parts, than Put or Spm, irrespective of the mode of application. The application of Put, Spd and Spm increased Spd concentrations in the roots. Considering that Spd is the main PA produced in the roots and that exogenously applied PAs are readily converted to Spd, it seems evident that Spd is the preferred PA for long-distance transport in plants. The cytokinins and auxins in Kelpak® play an important role in stimulating growth in plants. It is, however, the totality of different compounds in Kelpak® that gives it its unique growth stimulating ability. Polyamines, occurring within the seaweed contribute to this activity, having an active role in root production and thus increased plant growth. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Many of the anabolic effects of growth hormone (GH) are indirect, occurring through GH-stimulated production of insulin-like growth factor-I (IGF-I) by the liver. As well as being GH regulated, plasma IGF-I concentrations have been demonstrated to be dependent upon protein nutrition, with low protein diets being associated with reduced plasma IGF-I concentrations. This effect cannot be reversed by GH, suggesting that liver sensitivity to GH is impaired. To investigate the mechanisms through which protein supply affects GH sensitivity, primary cultures of ovine hepatocytes were grown in defined media. In a first experiment the media contained various fractions (0.2, 1.0, 5.0) of portal vein amino acid concentrations in fed sheep. In the second 24h incubation period, unstimulated IGF-I secretion was highly sensitive the concentration of amino acids in the media, with significantly greater release of basal IGF-I in 5x compared to either 1x (P<0.05) or 0.2x amino acid containing media. In a second series of experiments the effects of specific amino acid depletions was examined. Methionine depletion of 0.2x portal amino acid concentrations ablated the GH response second 24h of culture without affecting basal IGF-I release. By comparison ³H-leucine incorporation into secreted protein, following 20 hours of culture in defined media was significantly reduced in 0.2x aa (P<0.01) and 1.0x aa (P<0.05) media compared with 5.0x aa media, however secretory protein synthesis was unaffected by methionine depletion to 0.2x portal concentrations. The results suggest that amino acid availability regulates both basal and GH stimulated IGF-I release in ovine hepatocytes. Furthermore reducing methionine concentrations in the culture media to 0.2x portal concentrations diminishes GH response without compromising protein secretion.

Orientador: Dagoberto Martins / Coorientador: Pedro luís da Costa Aguiar Alves / Banca: Mariluce Pascoina Nepomuceno / Banca: Marcos Antonio Kuva / Resumo: Este trabalho teve por objetivo avaliar os efeitos da interferência da mucuna-preta no crescimento inicial de plantas de cana-de-açúcar, cultivar RB966928. O experimento foi conduzido em caixa de cimento com capacidade de 125L, preenchidas com substrato de um solo coletado da camada arável de um Latossolo Vermelho Escuro, e foi constituído por cinco tratamentos: (i) monocultivo da cana-de-açúcar, (ii) monocultivo da mucuna-preta, (iii) cultivo da cana-de-açúcar em convivência com a mucuna-preta em caixas separadas e agrupadas, (iv) cultivo da cana-de-açúcar em convivência com a mucuna-preta em caixas se comunicando e (v) cultivo da cana-de-açúcar em convivência com a mucuna-preta em caixas se comunicando, sem que a mucuna-preta entre em contato com a cana. Para o plantio da cana utilizou-se um fragmento do colmo (tolete) com três gemas aparentemente sadias e para a mucuna-preta foram utilizadas quatro plântulas por caixa, equivalente a 16 plantas m-2. O delineamento experimental adotado foi o de blocos casualizados com cinco tratamentos e sete repetições. As plantas de cana-de-açúcar foram avaliadas quanto à altura e o diâmetro do colmo principal. aos 30, 60 e 90 dias após o transplante (DAT) da mucuna-preta para as caixas. A avaliação final foi estabelecida aos 120 dias após o plantio da cana-de-açúcar, correspondendo a 90 DAT da mucuna-preta quando se avaliou a massa seca das folhas, dos colmos, área foliar e numero de perfilhos da cana-de-açúcar e a massa seca da parte aér... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work aims to evaluate the effects of velvet bean interference upon the initial growth of sugarcane plants, RB 966928 cultivar. The experiment was conducted in cement boxes with 125L capacity filled with a substratum composed of the arable part of an oxisol and consisted of five treatments: (i) sugarcane monoculture; (ii) velvet bean monoculture; (iii) sugarcane and velvet bean coexisting in separate boxes; (iv) sugarcane and velvet bean coexisting in united boxes; and (v) sugarcane and velvet bean coexisting but not contacting each other in united boxes. For sugarcane planting, a stem part (stalk cutting) with three apparently healthy buds were used and for velvet bean four seedlings were used per box, which stands for 16 plants m-2 . Experimental design was of random block design and had five treatments and seven replications. Sugarcane plants were evaluated on height and main stalk diameter at 30, 60 and 90 days after transplantation (DAT) of velvet bean to the parcels.The final evaluation occurred at 120 days after planting the sugarcane, which stands for 90 DAT of velvet bean, when it was evaluated also dry matter of leaves, stalks, leaf area and number of lateral shoots for sugarcane and dry matter of aerial parts and leaf area for velvet bean. All data was submitted to analysis of variance through F test, being the means compared by Tukey test at 5% probability. Height and diameter of main stalk were not affected by coexistence treatments with velvet bean until 90 ... (Complete abstract click electronic access below) / Mestre

Thesis (MTech (Agriculture)--Cape Peninsula University of Technology, 2018. / Choumollier (narrow-stem kale) (Brassica oleracea, L.) has been progressively used in recent years as a supplementary forage harvest in many countries with a temperate climate. Boron (B) and calcium (Ca) are the two most important elements for supporting plant structure and function of plasma membranes. Boron nutrition is vital for obtaining high quality yields in vegetables. The main objective of this study was to evaluate the extent to which boric acid concentration can affect growth parameters (plant height, leaf numbers, chlorophyll levels, and leaf size) of Brassica olereacea var. acephala at different stages of growth and development. Treatment comprised of four concentrations of boron (0.3 mg/kg, 0.4 mg/kg, 0.5 mg/kg and 0.6 mg/kg). Yield and physiological growth responses were measured during the course of the study to ascertain effectiveness and influence of boron treatments on the test crops. Leaves of B. oleracea were harvested at weekly intervals (W1, W2, W3, W4 and W5) after each treatment regimen for approximate basic mineral analysis and composition. Soil pH did not vary much among the various orchard blocks tested, regardless of soil depth. Exchangeable cations Na+ and K+ levels did not vary significantly, but Ca2+ and Mg2+ levels fluctuated considerably among orchards analyzed. The Control Orchard exhibited a higher P content than the other orchards. Ca, Mg, Cu and B levels did not vary significantly among the orchards, but Na, Fe and Zn levels were markedly raised in the Orchard treated with 0.3 mg/kg boron) relative to the Control Orchard. Chlorophyll fluorescence was significantly dependent on the treatment dose of boron as compared to control. Chlorophyll fluorescence also increased significantly with the growth period, i.e., the duration following the initial treatment at all doses of boron. Boron at all did not significantly affect leaf count, leaf length and plant height. The work may add to the body of knowledge on the influence of boron on the physiological performance, mineral contents and proximate composition of leaves of the species. Furthermore, the findings may have important applications in achieving high quality yields in vegetable crops.

Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2018. / Pelargoniums have been studied extensively for their medicinal properties. P. reniforme and P. sidoides in particular are proven to possess antimicrobial, antifungal and antibiotic abilities due to their high antioxidant potential from compounds isolated from their tuberous roots. These plants have now been added to the medicine trade market and this is now causing concern for conservationists and they are generally harvested from the wild populations. This study evaluated the effect of water stress alone and in conjunction with arbuscular mycorrhiza on two species of Pelargoniums grown in a soilless medium. The experiment consisted of five different watering regimes which were applied to one hundred plants of each species without inoculation with arbuscular mycorrhiza and to one hundred plants of each species in conjunction with inoculation with AM. All the plants in the experiment were fed with a half-strength, standard Hoagland nutrient solution at varying rates viz. once daily to pot capacity, every three days to pot capacity, every six days to pot capacity, every twelve days to pot capacity and every twenty-four days to pot capacity. The objectives of the study were to measure the nutrient uptake, SPAD-502 levels (chlorophyll production) and metabolite (phenolics) formation of both species, grown under various rates of irrigation and water stress, as well with or without the addition of arbuscular mycorrhiza at planting out. Each treatment consisted of 10 replicates. SPAD-502 levels were measured weekly using a hand held SPAD-502 meter. Determination of nutrient uptake of macronutrients N, K, P, Ca, Mg and Na and micronutrients Cu, Zn, Mn, Al and B were measured from dry plant material at the end of the experiment by Bemlab, 16 Van Der Berg Crescent, Gants Centre, Strand. Plant growth in terms of wet and dry shoot and root weight were measured after harvest. Determination of concentrations of secondary metabolites (phenolic compounds) were assayed and measured spectrophotometrically at the end of the experiment. The highest significant reading of wet shoot weight for P. reniforme was taken in treatments 1 and 2 with and without mycorrhiza i.e. WF1, WF1M, WF2 and WF2M, with the highest mean found in WF1 with no mycorrhiza. This indicates that under high irrigation AM plays no part in plant growth, possibly due to leaching. More research is necessary in this regard. With regard to wet root weight, this was found to be not significant in any of the treatments, other than the longest roots being found in WF4. Measurements for dry root weight showed that WF1,2,3 and 5 were the most significant at P≤ 0.001 significance, with the highest weight found at treatment being WF3 and WF3M. The highest mean of shoot length of the plants was measured in treatment WF2 at moderate watering, but no statistical difference was found with water application and mycorrhiza addition. Nutrient uptake was increased in P. sidoides in all the different watering levels in the experiment except in the uptake of Mg. AM inoculation showed an increase in the uptake of Ca, while absorption of N occurred at higher water availability. K uptake was enhanced by the addition of AM in high water availability and K utilisation decreased as water stress increased. Medium to low watering resulted in higher leaf content in P. sidoides while the interaction between water availability and AM inoculation increased chlorophyll production towards the end of the experiment.