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Manganese nutrition and photosynthesis in NAD-malic enzyme C-4 plants

Title from PDF of title page (University of Missouri--Columbia, viewed on February 24, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: Dr. Dale Blevins.Vita.Ph.D. University of Missouri--Columbia 2008.Based on their photosynthetic pathways, plants can be divided into three major groups: C-3, CAM, and C-4. In C-4 plants, the release of CO2 for Calvin cycle reactions in bundle sheath cells (BSC) involves one of the three principal enzymes: NADP-malic enzyme (NADP-ME), PEP-carboxykinase enzyme (PEPCK), and NAD-malic enzymes (NAD-ME). Of these three decarboxylating enzymes, only the activation of NAD-ME has an absolute requirement for Mn, therefore, leaf Mn concentrations could be critical for maximum NAD-ME activity and the continued supply of CO2 to bundle sheath cells. The objective of this research was to determine the Mn requirement for optimum photosynthesis and plant biomass production for two agriculturally important NAD-ME C-4 species, pearl millet (Pennisetum glaucum L. R. Br) and purple amaranth (Amaranthus hypochondriacus L.). These species were examined in parallel with two NADPME (no Mn activation required) species, corn (Zea mays L.) and sorghum (Sorghum bicolor L. Moench), and two C-3 species, wheat (Triticum aestivum L. cv. Ernie) and squash (Cucurbita pepo L. cv. straighneck) added as controls. Plants were grown in a complete nutrient solution with Mn concentrations ranging xiii from 0 to 100 [mu]M. Field grown pearl millet and purple amaranth received Mn from two sources, Mn beads and manganese chloride. Manganese concentration required for optimum photosynthetic rate and biomass production of the C-3 and NADP-ME C-4 species was found to be [about]2 [mu]M, which is the concentration commonly used in plant nutrient media. Manganese concentrations above 2 [mu]M had no significant effect on either photosynthetic rate or biomass production of these plants. Also, in C-3 and NADP-ME C-4 species, light saturated photosynthesis (Amax) was the highest for plants receiving 2-5 [mu]M Mn and no change was observed with increasing Mn concentration. In contrast, in both NAD-ME species, the optimum growth and photosynthetic responses required Mn concentrations 20-fold higher than those typically used in hydroponic media, and increasing Mn concentration from 10 to 75 [mu]M resulted in a 50% increase in photosynthetic rate in purple amaranth and a 36% increase in pearl millet. NAD-ME plants receiving higher Mn concentrations had greater responses to increasing photosynthetic photon flux density (PPFD), and at saturating light, pearl millet and purple amaranth receiving [greater than or less than]50 [mu]M Mn achieved higher Amax than those receiving lower Mn treatments. However, in all plant species, Mn treatment had little effect on the apparent quantum yield (AQY), perhaps indicating that at this range, light rather than Mn was limiting photosynthesis. Interestingly, Mn concentration higher than 2 [mu]M had little effect on stomatal conductance in all six tested species. This strongly implies that increased photosynthetic rates in NAD-ME species with higher Mn nutrition was a result of a better internal supply/utilization of CO2 and not of an improved stomatal conductance. In field experiments, Mn fertilization resulted in slightly increased leaf Mn concentrations and an up to [about]20% increase in photosynthetic rate. In general, Mn fertilization had little effect on seed mineral element composition or seed protein and oil content, but resulted in a slight increase in seed yield. This is, to my knowledge, the first information on the substantial, 20-fold higher Mn requirement for optimum photosynthesis and biomass production of NAD-ME C-4 plants, compared to other plant species. This finding should be considered in future research on NAD-ME C-4 crops, especially under soil conditions that decrease Mn availability for plant uptake. As more information is collected on NAD-ME C-4 plant biochemistry, physiology, and structure, more specific recommendations for nutrient requirements and more specific Mn application strategies can be developed.Includes bibliographical reference

Managing Nitrogen and Phosphorus Nutrients for Switchgrass Produced for Bioenergy Feedstock in Phosphorus-Deficient Soil

There is limited information available explaining the agronomic and economic relationships between yield and nitrogen and phosphorus applications to growing switchgrass produced in phosphorus-deficient soils. The objective of this study was to determine the effects of nitrogen and phosphorus fertilizers on feedstock yield and measures of expected total cost, gross revenue, net return, and breakeven price of feedstock produced in phosphorus-deficient soils in the southern Great Plains. Data were collected from a three-year, two-location agronomic field study conducted in south-central Oklahoma. Two discrete nitrogen treatments (0 and 134 kg ha-1) and four discrete phosphorus treatments (0, 30, 60 and 90 kg ha-1) were randomly assigned to small plots arranged in a randomized complete block designed (RCBD) study. Random effects mixed ANOVA models were used to estimate the effects of nitrogen, phosphorus and nitrogen by phosphorus interactions on feedstock yield and the economic variables specified. Results showed that, on average over site-years, switchgrass yield increases from 10.5 to 12.3 Mg ha-1 with the highest (101-kg ha-1) treatment; however, we found no statistical difference in net profitability between phosphorus treatments. Yield and net return did respond significantly to 135 kg-1 of N ha-1. Our results suggest that phosphorus-deficient soils do not seem to have the same impact on switchgrass yield and profitability as they do for the yields and profitability of other crops traditionally grown in this region.bioenergy feedstock, economics, phosphorus-deficient soils, nitrogen, switchgrass, Crop Production/Industries, Environmental Economics and Policy, Production Economics,

Effect of Priming and Seed Size on Germination and Emergence of Six Food-Type Soybean Varieties

Soybean (Glycine max (L.) Merr.), a good source of protein and oil, is used to produce nutritious isoflavone-rich soybean-based foods. The objectives of this study were (i) to determine the germination difference among soybean seeds in various seed sizes and (ii) to evaluate effects of seed pretreatment on germination and seedling emergence. Six varieties of different seed size class were used: (i) small size (MFS-561 and V08-4773), (ii) medium size (Glen and V03-47050), and (iii) large size (MFL-159 and V07-1897). Pregermination treatments include 0, 5, or 10 hours soaking and germinating/planting with or without nitrogen fertilizer. Large seed size varieties showed low germination rate and N addition caused the least reduction in germination in these seeds during the first 24 hours. While N had no effect on seed germination after 72 hours, growth in N treated seed was low. Seedling emergence was comparable across varieties in 2013 and water priming and N application had no effect. However, while varieties did not differ in final emergence for nonprimed seeds in 2014, water priming led to a high reduction in seedling emergence of large seed varieties in this study. Application of N fertilizer had no effect on seedling emergence in field experiments

The national environmental management authority's capacity to manage and control the potential environmental impact of the emerging oil and gas sector.

A Paper Submitted in Partial Fulfillment of the Requirements of the Bachelors of Laws DegreeThe purpose of this dissertation is to examine the capacity of Kenya's National Environmental Management Authority (NEMA) to manage the demands of the country's emerging upstream oil and gas industry. The need to analyze NEMA's capacity is a result ofrecently introduced legislation that now requires oversight oflntegrated Environmental Impact Assessment (lElA) over extractive projects by NEMA This paper tlms seeks to examine NEMA's capacity to comply with this change and comparatively analyzes the authority's managerial scope with that of Norway's Petroleum Safety Authority (NPSA) and its Petroleum Directorate (NPD), which is considered to be one of the world's leading institutions in the management of socio­ environmental impacts stemming from extractive projects.Tllis paper uses research metl10dology based on comparative research, policy transfer and material from conducting interviews. The aspects scrutinized are the laws and policies required to ensure success in tl1e Kenyan oil and gas industry as a result of prudent management of resources, emergency preparedness and proper safeguarding the e:ll..'ternal environmen

Economic Potential of Substituting Legumes for Synthetic Nitrogen in Warm Season Perennial Grasses used for Stocker Cattle Grazing

Stocker cattle grazing warm season perennial grasses is an important economic activity in the southern Great Plains. Substantial increases in the price of nitrogen fertilizer is negatively affecting forage producers’ profitability. Two alternative nitrogen management systems that use annual and perennial legumes have been developed for bermudagrass pastures. The goal of the study is to determine if the legumes systems are more profitable than the conventional practice of applying synthetic sources of nitrogen. Results of the two-year grazing study show that the legume systems could not compete economically with the common practice.economics, grazing, legumes, bermudagrass, nitrogen fertilizer, stocker cattle, Crop Production/Industries, Farm Management, Production Economics,

Algal symbionts of the freshwater sponge Ephydatia muelleri

The freshwater sponge, Ephydatia muelleri, is an emerging model system for studying animal:microbe symbioses. Intracellular green microalgae are one of the more common symbionts that live in a facultative mutualism with E. muelleri. While these symbioses have long been known, the identity of the algal symbionts in E. muelleri cells has not been studied in detail. Here, we isolate and characterize endosymbiotic algae from E. muelleri collected from different geographic locations. We find that the algae can be transmitted through asexually produced gemmules and importantly that they can form symbioses with different, differentiated sponge cell types in the adult sponge. Our findings indicate that at least two algal lineages form endosymbioses with E. muelleri. One of the lineages includes species commonly found in samples from two locations in Canada and one in the United States (clade 1: closely related to Auxenochlorella pyrenoidosa). The other clade includes algae found in sponges from one site in Maine, USA, and Lewiniosphaera symbiontica, which is a strain isolated in 1956 from the freshwater sponge Spongilla. We compared microbiomes found in cultures of microalgae as well as the original sponge hosts, and found that very similar bacterial microbiomes associate with both clades (91 orders of Bacteria are shared among the samples we compared). The microbiomes found in the cultures resemble, with a high degree of overlap, the microbiome associated with the sponge host

Willow short-rotation production systems in Canada and Northern United States: A review

Willow short rotation coppice (SRC) systems are becoming an attractive practice because they are a sustainable system fulfilling multiple ecological objectives with significant environmental benefits. A sustainable supply of bioenergy feedstock can be produced by willow on marginal land using well-adapted or tolerant cultivars. Across Canada and northern U.S.A., there are millions of hectares of available degraded land that have the potential for willow SRC biomass production, with a C sequestration potential capable of offsetting appreciable amount of anthropogenic green-house gas emissions. A fundamental question concerning 1 sustainable SRC willow yields was whether long-term soil productivity is maintained within a multi-rotation SRC system, given the rapid growth rate and associated nutrient exports offsite when harvesting the willow biomass after repeated short rotations. Based on early results from the first willow SRC rotation, it was found willow systems are relatively low nutrient-demanding, with minimal nutrient output other than in harvested biomass. The overall aim of this manuscript is to summarize the literature and present findings and data from ongoing research trials across Canada and northern U.S.A. examining willow SRC system establishment and viability. The research areas of interest presented here are the crop production of willow SRC systems, above- and below-ground biomass dynamics and the C budget, comprehensive soil-willow system nutrient budget, and soil nutrient amendments (via fertilization) in willow SRC systems. Areas of existing research gaps were also identified for the Canadian context