published_or_final_version / Botany / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references. Also available in print.

Thesis (Ing. Agroindustrial)--Universidad Técnica del Norte, Facultad de Ingeniería en Ciencias Pecuarias y Ambientales, Escuela de Ingeniería Agroindustrial, 2005. / Reproduced from copy at BYU's Benson Institute. Includes bibliographical references (leaves 93-94).

Thesis (M. Tech.: Biotechnology)-Dept. of Biotechnology and Food Technology, Durban University of Technology, 2008. xiv, 103 leaves : ill. / Phytoremediation is an emerging technology where specially selected and engineered metal-accumulating plants are used for bioremediation. Amaranthus dubius (marog or wild spinach) is a popular nutritious leafy vegetable crop which is widespread especially in the continents of Africa, Asia and South America. Their rapid growth and great biomass makes them some of the highest yielding leafy crops which may be beneficial for phytoremediation. This study was undertaken to evaluate the potential of A. dubius for the phytoremediation of Chromium (Cr), Mercury (Hg), Arsenic (As), Lead (Pb), Copper (Cu) and Nickel (Ni). Locally gathered soil and plants of A. dubius were investigated for the metals from a regularly cultivated area, a landfill site and a sewage site. Metals were extracted from the samples using microwave-digestion and analyzed using Inductively Coupled Plasma – Mass Spectroscopy (ICP-MS). Further experiments were conducted with plants from locally collected seeds of A. dubius, in a tunnel house under controlled conditions. The mode of phytoremediation, the effect of the metals on the plants, the ability of the plant to extract metals from soil (Bioconcentration Factor - BCF), and the ability of the plants to move the metals to the aerial parts of the plants (Translocation Factor - TF) were evaluated for the different metals. Finally, A. dubius was micro-propagated in a tissue culture system with and without exposure to the metal, and the effect was studied by electron microscopy.

Thesis (M. Tech.: Biotechnology)-Dept. of Biotechnology and Food Technology, Durban University of Technology, 2008. xiv, 103 leaves : ill. / Phytoremediation is an emerging technology where specially selected and engineered metal-accumulating plants are used for bioremediation. Amaranthus dubius (marog or wild spinach) is a popular nutritious leafy vegetable crop which is widespread especially in the continents of Africa, Asia and South America. Their rapid growth and great biomass makes them some of the highest yielding leafy crops which may be beneficial for phytoremediation. This study was undertaken to evaluate the potential of A. dubius for the phytoremediation of Chromium (Cr), Mercury (Hg), Arsenic (As), Lead (Pb), Copper (Cu) and Nickel (Ni). Locally gathered soil and plants of A. dubius were investigated for the metals from a regularly cultivated area, a landfill site and a sewage site. Metals were extracted from the samples using microwave-digestion and analyzed using Inductively Coupled Plasma – Mass Spectroscopy (ICP-MS). Further experiments were conducted with plants from locally collected seeds of A. dubius, in a tunnel house under controlled conditions. The mode of phytoremediation, the effect of the metals on the plants, the ability of the plant to extract metals from soil (Bioconcentration Factor - BCF), and the ability of the plants to move the metals to the aerial parts of the plants (Translocation Factor - TF) were evaluated for the different metals. Finally, A. dubius was micro-propagated in a tissue culture system with and without exposure to the metal, and the effect was studied by electron microscopy.

The following lines of white-seeded amaranth were tested in three locations within the Imbabura province of Ecuador: Ecu-0113, Ecu-0014, Ecu-2210, Ecu-4737, and Ecu-4744. The three locations used were Caranqui, Urcuquí, and Pucará which are 2228, 2423, and 2513 meters above sea level respectively. The objectives of this study were: 1) to identify which of the five experimental amaranth lines respond best at each altitude, 2) to establish which of the three locations is most appropriate for cultivation, 3) to understand the vegetative period of the five lines in each location, 4) to analyze which of the five experimental lines possesses the best characteristics in regard to yield, and 5) to determine the cost of producing one hectare of amaranth. The hypothesis was that at least one of the five amaranth lines has a different response in each of the three locations. A randomized block design with five treatments (varieties) and three repetitions in each location was used. Tests of significance were conducted via the Tukey method at 0.05 examining stem length, panicle length, yield, and days to harvest for all varieties and locations. Combined analysis was used to evaluate variety interaction by location. Significant differences in stem length were observed among the different locations and varieties. The Ecu-0113 variety reached lengths of 1020.00 mm. In regard to panicle length, significant differences were also observed among different locations and varieties. The most promising locations were Urcuquí and Caranqui while the most promising varieties were Ecu-0113 and Ecu-4737. Significant differences in grain yield were also observed among the different locations and varieties. In the Urcuquí area, the Ecu-0113 variety had the highest yield with a yield of 2404.24 kg/ha. In the Caranqui and Pucará areas, the Ecu-2210 variety had the highest yields with values of 1605.88 and 833.99 kg/ha respectively. The Ecu-4744 variety was the first ready to harvest in all three locations while the variety Ecu-2210 was the last. The production of one hectare of amaranth resulted in a cost-benefit ratio of 2.48 which means that for every dollar invested, $1.48 USD was recovered. In the Imbabura province, Urcuquí and Caranqui can be considered favorable environments for cultivation and Ecu-0113 and Ecu-2210 were the varieties that exhibited the greatest production potential. We recommend planting the Ecu-0113 variety in Urcuquí and the Ecu-2210 variety in Caranqui and Pucará to obtain maximum grain yield.

Thesis(M.Sc. Agricultural Management (Horticulture)) -- University of Limpopo, 2021 / Amaranthus species, with their adaptability to grow under various agro-ecologies and soil types, have gained considerable attention in food security due to their high nutritional content. However, various Amaranthus species are host to the root-knot (Meloidogyne species) nematodes, with limited information on how the pest could affect the nutritional composition of the crop. In other crops, infestation with Meloidogyne species have deleterious effects on accumulation of certain essential mineral nutrient elements. However, the influence of Meloidogyne species on essential mineral nutrient elements had not been documented on Amaranthus. The objectives of the study, therefore, were to determine the influence of infestation by Meloidogyne species on growth and accumulation of selected malnutrition elements in four exotic Amaranthus relative to the local cultivar under both greenhouse and field conditions. In the greenhouse study, hardened-off seedlings were transplanted into 20-cm diameter plastic pots containing a steam-pasteurised growing mixture. The 5 × 2 factorial experiments were arranged in a randomised complete block design, with five replications. The first and second factors were five Amaranthus cultivars and two Meloidogyne species, namely, M. incognita and M. javanica. At 60 days after inoculation, plant growth and nematode variables were assessed using standard procedures. Roots of all five Amaranthus cultivars were heavily galled, with limited cultivar × nematode interactions on plant variables. Additionally, the common factor that influenced either plant or nutrient element variables was the cultivar type, whereas those of nematodes were highly variable, particularly on nutrient elements. Three best performing cultivars were further tested under field conditions under nematode infested and untreated control plots. An exotic cv. ′Tanzania′ had higher dry shoot mass, plant height and stem diameter, and accumulated higher Ca and K content than ′Candatus′ and ′Local 33′. Overall, the cultivar × nematode interaction reduced Na content in leaf tissues of Amaranthus cultivars under field conditions. / University of Venda, University of Limpopo and Agricultural Research Council

This study was conducted in two locations: Pucará (2,413m above sea level) and Mojandita (2,922m above sea level), both of which are found in the province of Imbabura, Ecuador. The objectives of this study were to: characterize the morphological and agronomic traits as well as the overall quality of the ten amaranth accessions in this study; identify the accessions with the highest yield and biomass; determine the nutritional characteristics of the experimental accessions; and determine the cost of production of amaranth per hectare. The following null hypothesis was assumed: the agronomic and nutritional characteristics of the ten accessions in this study are equal in both locations. A randomized block design with ten treatments and three repetitions was employed for each location. The following tests of significance were performed: Tukey test at the 5% significance level for accessions, DMS at 5% for locations and Combined Analysis for the variety x location interaction. The following lines were used: ECU-0014, ECU-0113, ECU-2210, ECU-4737, ECU-4744, which represented pale-seeded grain types, and ECU-0069, ECU-0082, ECU-0102, ECU-0123 and ECU-0162 represented dark-seeded grain types. These accessions were analyzed for: plant height, diameter of the base of the stem, stem length, panicle length, grain/plot yield. Based on the results of this study, we conclude that no significant difference exists between the accessions on the basis of plant height and stem length in either location. For stem diameter, panicle length, and yield, however, significant differences among the accessions were detected. Between locations, the most promising results were observed in Pucará. The accession ECU-2210 gave the highest yield in Mojanda, with 1,300 kg/ha, while the accession ECU-0014 had the highest yield in Pucará, with 1,400 kg/ha. Overall, the best protein and iron content was observed in Mojanda; the accessions ECU-0162 and ECU-4744 had the highest percentage of protein, with 14.93% and 14.58% respectively. The highest observed iron content was 465.0 ppm in the accession ECU-0102. The cost of producing one hectare of cultivated amaranth grain is $1,543.95. The sale of this investment totaled $2,520, giving a cost-benefit ration of $0.63. Growing the accessions ECU-0612 and ECU-4744 is recommended if high protein content is desired, while the accession ECU-0102 is recommended in order to obtain the highest iron content. To obtain the highest yield per square meter, the accessions ECU-2210 is recommended at altitudes of 2,900m above sea level, while ECU-0014 is recommended for altitudes less than 2,600m. Based on the results of this study, it is not recommended that amaranth be planted at altitudes higher than 3,000m.

The present investigation was made in the Experimental Farm "La Pradera", located in the province of Imbabura, the parish of San José de Chaltura, to 1350 meters above sea level and an average temperature of 16, 4⁰ C. To analyze the effect of the chemical and organic fertilization in amaranth of variety INIAP "Alegría" was the primary target of the investigation. The field work was made in a lapse of 6 months. The design of complete blocks (DBCA) with 15 treatments was used at random and three repetitions by treatment. The experimental unit was 18 m². It was evaluated by means of analysis of variance and the Turkey test at 5%. The factors in this study are constituted by the elements N, P, S and organic fertilizer. The analyzed variables were: number of plants; days to the flowering; days to the harvest; height of plants; biomass; extraction of nutrients; and grain yield. The number of plants presented significant difference to 1% for treatments and to 5% for blocks, the treatments that reached the greater number of plants are T11 (80-60-40-0) and T14 (0-0-0-10) with an average of 30 and 29 plants of amaranth in 0.50 linear m respectively. The treatment T4 (120-60-20-0) presented the greater height at 45 days of seedtime, with an average of 24.10 cm. The height of plants at flowering I present significant statistical results highly is the T4 (120-60-20-0) and T5 (160-60-20-0) respectively present values of height of 119.30 and 103.40 centimeters. The height of plants at the harvest determines significant difference for treatments the highest being the T5 (160-60-20-0), the one that reached the greatest height with an average of 148, 11 centimeters. The days to the flowering of the amaranth were between 70 and 85 days from seedtime and the days to the harvest were between 143 and 152 days. The treatment that reached the greater mean efficiency was the T5 (160-60-20-0) with 2583, 69 Kg/ha unlike the control who reached an average of yield of 686, 66 Kg/ha. In the organic treatments the greater yield registry in T15 (0-0-0-15) where 15 tons of organic fertilizer by hectare was used resulting in 1672.59 Kg/ha.