The experiments discussed in this thesis are part of a continuing research program testing the influences of chemical fertilizers on the survival, growth and cone production of Douglas fir in coastal British Columbia. This study was initiated in the early spring of 1963 by the Consolidated Mining and Smelting Company of Canada Limited, Trail, B. C, and the Faculty of Forestry of the University of British Columbia. The thesis summarizes the influence of several chemical fertilizers on the survival and growth of planted Douglas fir seedlings from the beginning of the study to the present date. During the first phase of this study, the responses of planted Douglas fir to chemical fertilization have been investigated by four experiments. The first experiment, a trial of slowly soluble fertilizers, was initiated at the end of April, 1963, at three locations: U.B.C. Campus nursery, and TS 3 and TS 32b in the U.B.C. Research Forest. In a split plot design arrangement, Magamp, Urea, Aqua humus, Cxamide, Thiourea, Sludge and a bark product were dumped into or mixed with the soil in the holes made for the planting of four size classes of Douglas fir seedlings. At the end of April, 1964, the trial of slowly soluble fertilizers was repeated on the same locations. This time, the response to three Magamp particle sizes (commercially distributed Magamp, Magamp -6+8, and Magamp -8+10) as well as Sludge, Uramite and Thiourea was tested. Additional information concerning survival of planted Douglas fir seedlings was obtained from the Tahsis Logging Company at Gold River, B. C, which, in 1963, carried out a similar experiment with the same slowly soluble fertilizers. In all cases, the use of more readily soluble sources of nitrogen resulted in excessive mortality. The climate in 1963 and 1961; substantially influenced the survival and growth of the fertilized seedlings. In the second experiment, the response of Douglas fir seedlings planted in 1953, 1956 and 1959 to ammonium nitrate was investigated in the U.B.C. Forest. Nitraprills was applied randomly at six levels (0 to 800 lb. of nitrogen par acre) to a total of 360 trees. Treatments were applied in May of 1963 and 1964 at the time of flushing of vegetative buds. To date, the fertilization has improved neither height growth nor diameter increment and has had no influence on cone production. The third experiment was initiated at the end of December, 1963, in the U.B.C. Campus greenhouse. A. six-factor experiment was designed to test the responses of 2+0 planted Douglas fir seedlings to Magamp and Mitraprills. The fourth experiment was planned to compare the effects of Magamp and Nitraprills on 2+0 planted Douglas fir seedlings in the field in the U.B.C. Research Forest during the summer of 1964. The results of the third and fourth experiments have proved that the slowly soluble Magamp is more advantageous to seedlings than is the rapidly soluble Nitraprills when both are applied at the time of planting. However, these analyses have shown limited advantage to using either fertilizer during planting. The studies of these fertilizers should be continued and extended to include other sources of slowly soluble nitrogen. / Forestry, Faculty of / Graduate

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The growth and Nitrogen fixation by one low salt tolerant alfalfa (Medicago sativa L.) and two germination salt tolerant selections inoculated with were investigated at two salt levels (0, -0.6 Mpa) and two N rates (1, 5ppm) using a system which automatically recirculates a nutrient solution. The high level of salinity (-0.6 Mpa osmotic potential of culture solution) resulted in substantial reduction in the N fixation percentage and total fixed N. The effect of salinity was more pronounced for later cuttings than for the earlier cutting. The N fixation percentages were substantially decreased by increasing N level and the reduction was enhanced by time. The N treatment levels did not exhibit a significant effect on total fixed N. Cultivars did not differ in either growth or N fixation. However, the interaction of N and salinity significantly decreased the percentage and amount of N fixation.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Master of Science. Johannesburg 1995 / This project represents the development of a comprehensive description of the growth of two plant species (namely white clover and Italian ryegrass) in a mixed canopy: Particular attention has been paid to the impact of two symbiotic associations (legume root nodules and vesicular arbuscular mycorrhizae) on the growth of the two plant species. [Abbreviated Abstract. Open document to view full version] / MT2017

Orientador: Vera Lex Engel / Banca: Antonio Carlos Galvão de Melo / Banca: Giselda Durigan / Resumo: A facilitação e a inibição da regeneração natural por plantações florestais já foram demonstradas em regiões tropicais. Os mecanismos de facilitação e a influência das espécies plantadas na trajetória do sistema em regeneração, no entanto, ainda não estão completamente elucidados. Objetivou-se neste estudo investigar se, a partir das características funcionais das espécies do dossel, há diferenças nos processos de colonização do sub-bosque. O estudo foi realizado na região central do Estado de São Paulo, no município de Botucatu. Foram comparadas quatro espécies arbóreas plantadas há cerca de 80 anos como sombreadoras de cafezais: Anadenanthera colubrina (Vell.) Brenan var. cebil (Griseb.) Altschul (fixadora de nitrogênio); Araucaria angustifolia (Bertol.) Kuntze. (não fixadora); Piptadenia gonoacantha (Mart.) J.F. Macbr. (fixadora); Hymenaea courbaril L. (não fixadora). Todos os indivíduos arbustivo-arbóreos maiores que 0,5 m de altura foram medidos e identificados, em 25 parcelas de 10 x 10 m em cada talhão. O Índice de Área Foliar (IAF) de cada parcela foi determinado ao final da estação chuvosa (março) e ao final da estação seca (Setembro), de modo a detectar diferenças no padrão de sombreamento das áreas. No início da estação seca, foi coletada a serapilheira depositada no piso florestal com auxílio de um gabarito, de modo a verificar sua massa seca e sua influência na densidade e riqueza da regeneração natural. Levantamentos microclimáticos foram feitos durante um semes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Facilitation and inhibition of natural regeneration through forest plantations have been demonstrated in tropical regions. However, the facilitation mechanisms and its influence on succession trajectory are no so clear. We aimed at investigating whether there were differences amongst colonization processes of the understory, based on functional characteristics of the canopy species. The study site was located in central São Paulo State, Southeastern Brazil. We compared four abandoned forest stands that were used as shaded coffee plantations around 80 years ago: 1) Anadenanthera colubrina (Vell.) Brenan var. cebil (Griseb.) Altschul (nitrogen-fixing); 2) Araucaria angustifolia (Bertol.) Kuntze. (non-fixing); 3) Piptadenia gonoacantha (Mart.) Macbr. (nitrogen-fixing); and 4) Hymenaea courbaril L. (non-fixing). All understory individuals above 0.5 m tall were measured and identified at the species level, in 25 plots of 10 x 10 m in each stand. Leaf Area Index (LAI) was determined inside each plot at the end of the rainy season (March) and at the end of the dry season (September), in order to detect differences in shading pattern among the areas. Ground litterfall was collected in each plot using a 0.25 m² template, in order to assess the dry weight and its influence on natural regeneration. Microclimate data were also collected during six months, to check for differences among stands. The results show high rates of self-recruiting on A. colubrina var. cebil and P. gonoacantha st... (Complete abstract click electronic access below) / Mestre

Orientador: Carmen Sílvia Fernandes Boaro / Banca: Gisela Ferreira / Banca: Ivan de La Cruz Chacón / Resumo: A espécie Annona emarginata (Schltdl.) H. Rainer 'araticum-de-terra-fria' possui grande potencial como porta-enxerto para o híbrido atemoia (Annona cherimola Mill. x Annona squamosa L.), conferindo resistência contra a broca do tronco, característica dependente de seus metabolismos primário e secundário. O nitrogênio é um elemento essencial na síntese de aminoácidos, proteínas, entre elas, a Ribulose 1,5 - difosfato (Rubisco), ácidos nucleicos, clorofila e metabolitos secundários, entre outros importantes constituintes celulares. Além dessas funções, deve ser considerada sua relação de competição com o CO2 e síntese de terpenos, por agentes redutores e esqueletos carbônicos. Deste modo, o presente estudo objetivou avaliar a influência da variação do nível de nitrogênio na solução nutritiva, na produtividade e composição de voláteis foliares durante o desenvolvimento inicial de mudas de A. emarginata. Para o estudo da produtividade foram avaliadas as trocas gasosas, a atividade das enzimas nitrato redutase, catalase, peroxidade, superóxido dismutase, a peroxidação lipídica, a produção de massa seca de raiz, caule e folhas, área foliar, diâmetro de caule, razão de área foliar, taxa de assimilação líquida, taxa de crescimento relativo, peso específico de folhas, distribuição de massa seca para os diferentes órgãos do vegetal, razão de massa foliar e a composição de voláteis extraídos das folhas. As plantas cultivadas com níveis intermediários de nitrogênio apresentaram maior eficiência de carboxilação e taxa de assimilação de CO2. A atividade da nitrato redutase variou com os diferentes níveis de nitrogênio a que as plantas foram submetidas. No maior nível de nitrogênio utilizado, as plantas com menor produtividade, demostraram competição entre a fixação de nitrogênio, assimilação de CO2 e síntese de terpenos. A atividade das ... / Abstract: The species Annona emarginata (Schltdl.) H. Rainer 'araticum-de-terra-fria' has great potential as a rootstock for this hybrid atemoya (Annona cherimola Mill. X Annona squamosa L.) conferring resistance to stem borer. This resistance may be related to primary and secondary metabolisms. Nitrogen is an essential element on the synthesis of amino acids, proteins such as Ribulose 1,5 - diphosphate (Rubisco), nucleic acids, chlorophyll, secondary metabolites, and other important cellular constituents. Besides these functions, it should be considered competing relation to CO2 by reducing agents and carbon skeleton. Therefore, the present study aimed to evaluate the influence of variation in the level of nitrogen in the nutrient solution on yield and composition of the leaf volatile during the early development of seedlings of A. emarginata. To study the productivity gas exchange were evaluated, the activities of nitrate reductase, catalase, peroxidase, superoxide dismutase, lipid peroxidation, the dry weight of roots, stems and leaves, leaf area, stem diameter ratio leaf area, net assimilation rate, relative growth rate, leaf specific weight, dry weight distribution to different organs of the plant, leaf mass ratio and the composition of volatiles extracted from the leaves. Plants grown with intermediate levels of nitrogen had higher carboxylation efficiency and CO2 assimilation rate. Nitrate reductase activity varied with different levels of nitrogen that the plants were submitted. In the largest amount of nitrogen, plants with lower productivity, demonstrated competition between nitrogen fixation, CO2 assimilation and synthesis of terpenes. The activity of antioxidant enzymes prevented lipid peroxidation in plants subjected to different levels of nitrogen. Gas exchange, the activity of nitrate reductase and antioxidant enzymes in plants grown with 78.75 and 118.12 mg L-1 N contributed their best ... / Mestre

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This study sought to explore the relationship between spatial scale and canopy chemistry through the use of remotely sensed videography data and total nitrogen content of potato petioles. A range of broad band spectral indices were employed along with standard red and green wavelengths to define an optimum scale or range of scales in which the accuracy of predicting leaf canopy chemistry could be improved. Difficulties inherent within video imagery due to the method in which the National Television System Committee's (NTSC) analog signal is comprised were studied. Spectral quantification of the video signal was not possible within the study, instead attention centered on showing the consistent and well correlated results that could be obtained using such data. Spectroradiometer measurements were also obtained for comparison with video response. Correlation between the two sensors was low, primarily due to the nature of the respective signals. Multispectral imagery was obtained from SPOT for spatial resolution comparison. The light research aircraft employed to collect the aerial video imagery proved to be a versatile and cost effective alternative to traditional remote sensing platforms. The data produced within the study support the project objectives in defining regions of high to low prediction accuracy. A reduction in spatial scale increases the ground area represented by an individual pixel and reduces the quantity and quality of information available to the sensor. The study illustrated a possible spatial resolution breakoff point at which nitrogen content prediction accuracy is greatly diminished. / Graduation date: 1995

The effect of planting density and nitrogen (N) fertilization on growth, yield, and N partitioning in young and mature 'Bluecrop' blueberry plants was studied over a two year period. Depleted 15N-ammonium sulfate was applied at different rates and on different dates in a mature planting, and at different rates in a young, newly established planting during the first year of study (2002). Non-labeled fertilizer was applied the second year (2003). Three rates of N fertilizer (0, 100, and 200 kgha1 of N) in combination with two in-row spacing treatments (0.45 m and 1.2 m) were studied in the mature planting. In addition, three different dates of application of labeled fertilizer at the same rate was also tested. In a young planting, four N fertilizer rates (0, 50, 100 and 150 kgha^-1 of N) were applied in the establishment year. In all studies, the N fertilizer was divided into three equal portions and applied from April through June. Plants were destructively harvested from the field and divided into parts on 6 to 11 dates from Feb. 2002 to Jan. 2004, depending on experiment. Plant parts were analyzed for dry weight (DW), N, and '5N concentration (%) and nitrogen derived from the fertilizer (NDFF) calculated. Shoots on mature plants were divided into small (S), medium (M), large (L) and extra large (XL) categories, based on length, and the effect of N and plant spacing on the number, DW, and flushes of growth characterized. The number of shoots per plant ranged from 249 to 298 with plants spaced at 1.2 m having more shoots than those at 0.45 m. Fifty percent of the shoots in the plant were S, whereas only 8% were XL. Nitrogen rate did not affect shoot number, but higher rates of N did increase shoot biomass and the proportion of XL and S shoots. One to four flushes of growth per shoot were recorded, with the number of flushes dependent upon shoot size; 60 to 80% of S shoots had only one flush of growth compared to 8 to 12% of XL shoots. Eighty percent of total shoot biomass was in the first flush of growth and 20% in the second or later flushes with no effect of in-row spacing or N rate. Yield per plant was 30 to 80% greater at 1.2 m than at 0.45 m. However, yield per hectare was 30 to 140% higher in plants at 0.45 m than those at 1.2 m. The roots and crown were the heaviest organs, whereas roots and leaves contained the most nitrogen. Percent biomass partitioning was affected by sampling date for all plant parts, and by in-row spacing only for the crown and three-year-old wood. In the mature planting, total plant DW was affected by sampling date, in-row spacing, and N fertilization rate. Plants at the 1.2 m in-row spacing had 32% more DW over time than those at 0.45 m, but less DW per hectare. Nitrogen fertilization increased plant DW in the second year of study, affecting mainly the younger plant parts. Plants fertilized with 200 kgha^-1 of N had the greatest total N. Nitrogen concentration (%N) varied greatly with plant part and was affected by sampling date and N fertilization rate. Younger tissues had the highest %N in spring (3.5%) and flower buds in winter (2.4%). Total plant NDFF increased from Apr. 2002 to May 2003. The lowest NDFF per plant and per hectare was found in Apr. 2002, when almost 60% of the NDFF was in the new shoots. Nitrogen fertilization rate and in-row plant spacing had an impact on total NDFF accumulated per plant and per hectare. More total NDFF was found in plants fertilized with 200 kgha^-1 of N than with 100 kgha^-1 of N, independent of spacing. Fertilizer recovery was 17% for plants at 1.2 m and 23% for plants at 0.45 m, independent of N fertilization rate. Partitioning of 15N (mg per plant part) and percent of total 15N per part changed with sampling date. Nitrogen fertilization rate and spacing did affect the total amount of fertilizer-15N present in each part, but percent partitioning of 15N was only affected by plant part. Plants at 1.2 m had a higher percentage of 15N partitioned to the crown and three-year and older wood, but reduced partitioning to large roots than plants at 0.45 m. Application date had a large effect on the total amount of NIDFF recovered in the plant at the end of the first season. Application of N fertilizer in either April or May resulted in five times more NDFF in the plant than fertilizer application in July. Percent partitioning of NDFF was also affected by application date. Late fertilization resulted in labeled N allocated mainly to small roots, leaves and shoots, whereas spring-applied fertilizer was allocated mainly to leaves and fruits. In the new planting, established using two-year-old plants, N fertilization rate affected plant dry weight, total N content, percent NDFF, and fertilizer recovery. By October, plants fertilized with 50 kgha1 of N had the largest dry weight and N accumulation. Ammonium toxicity was observed in plants fertilized with 100 and 150 kgha1 of N. Percent NDFF was 60% and 67% for the 50 and 100 kgha^-1 of N, respectively. Fertilizer recovery reached a maximum of 10 to 17% in October, depending on N fertilization rate. / Graduation date: 2006

The usefulness of preplant nitrogen (N) in establishing alfalfa in colder production areas has not been well characterized. This study was conducted to determine the effect of preplant N and soil temperature on yield, percent N derived from biological nitrogen fixation (PBNF), and shoot N concentration in alfalfa (Medicago sativa L. cv. 'Vernema'. Field experiments were conducted in 1987 and 1988 at Powell Butte, OR, to determine the effect of five levels of preplant N (0, 10, 20, 40, 60 kg ha⁻¹) on yield and shoot N concentration of alfalfa. Growth chamber experiments were conducted from 1989 through 1991 to examine the effect of five levels of preplant N (0, 10, 20, 40, 80 kg ha⁻¹) and three day/ - night soil temperatures (18/12°C, 24/16°C, 27/21°C) on yield, PBNF, and shoot N concentration of alfalfa. In field experiments, preplant N had no effect on shoot N concentration in either year. In 1987 there was no effect of preplant N on dry matter yield. Application of 20-40 kg N ha⁻¹ preplant N increased dry matter yield in 1988. In growth chamber experiments, the highest rate of dry matter accumulation occurred at a soil temperature of 24/16°C. At 18/12°C and 24/16°C, 40 kg ha⁻¹ preplant N resulted in increased shoot and root dry matter yield. At 18/12°C, 80 kg ha-¹ preplant N increased PBNF 14% relative to the zero N control. There was no effect of preplant N on PBNF in plants grown at 24/16°C and 27/- 21°C. The rates of shoot N accumulation were similar at 18/12°C and 24/16°C, and were higher than at 27/21°C. Shoot N concentration was not affected by preplant N treatments. The use of 20-40 kg ha⁻¹ preplant N may result in increased yield without decreasing PBNF when: 1) soil temperature remains below 15°C for at least two weeks after planting, and 2) soil nitrate level is less than 16 mg kg⁻¹. Proper assessment of the use of preplant N in alfalfa establishment requires a careful consideration of both soil temperature and soil N availability. / Graduation date: 1992