京都大学 / 新制・課程博士 / 博士(理学) / 甲第23740号 / 理博第4830号 / 新制||理||1691(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 鹿内 利治, 教授 松下 智直, 准教授 竹中 瑞樹 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Several photosynthetic inhibitors were screened for relative photosynthetic reduction on leaves of greenhouse-grown peach trees. The most effective were 8% Vapor Gard, 10M diurcn, 10⁻³M ABA, and 10⁻³M terbacil, all of which reduced net photosynthesis (Pn) rates by 50% or more by 1 day after treatment without causing excessive phytotoxicity. Of these 4 treatments, terbacil at 10⁻³M gave the most consistent effects; treated leaves re-established near normal Pn rates within a week of treatment. At 1, 3, and 7 days after treatment with terbacil at 10⁻³M, Pn rates were 1.1, 9.0, and 16.6 mgCO₂ dm⁻² hr⁻¹ , respectively, compared with a pretreatment rate of 19.7. Terbacil was applied as limb treatments to bearing peach trees in the field to determine fruit thinning activity. Treatments were: single applications of 1000 or 2000 ppm, double applications a week apart of 1000 ppm, or 2000 followed by 1000 ppm. All treatments significantly reduced fruit number. Fruit drop was 73 to 90% on treated limbs compared to 20% on non-thinned check limbs. Only the single 1000 ppm treatment resulted in fruit size similar to the hand-thinned check, however, all treatments increased fruit size over the non-thinned checks. / M.S.

A series of experiments was conducted to determine the effect of light, auxin, carbohydrate levels, mineral nutrients and rooting on the net photosynthetic (Pn) rate of unrooted Ilex crenata Thunb. 'Helleri' cuttings. Optimal photosynthetic activity occurred at PAR levels of about 600 micro-Einsteins m⁻² sec⁻¹. The emergence of roots increased the Pn rate. High plant carbohydrate levels were correlated to lower Pn rates while higher Pn rates were correlated to lower CHO levels. These relationships may be indicative of source-sink interactions on the Pn rate of Helleri holly cuttings. An exogenous basal application of indolebutyric acid (IBA) contributed to an increase in cutting Pn, as was the case with the addition of mineral nutrients. / M.S.

More than 20 million clonal loblolly pines have been planted throughout the southeastern United States. Fertilizer has been applied to more than 6.5 million hectares of plantations to alleviate deficiencies of nitrogen and phosphorus that limit growth. Because cloning loblolly pine in large numbers has only become possible in the last decade, it is unknown how clones may respond differently to fertilizer application. Growth, growth efficiency, and biomass partitioning responses to fertilizer application were investigated among 25 clones planted in the Virginia Piedmont. Closely related clones varied in their fertilizer stem volume responses, but not enough to be statistically significant (p = 0.11). Clones varied in growth efficiency and partitioning to individual tissues, but clone-by-fertilizer interactions were not observed. Clonal variability was observed in root morphology, and maximum rooting depth showed a significant clone-by-fertilizer interaction. Clones with rapid growth rates can be selected with a range of other desirable traits. Short-term (i.e. weeks) responses to fertilization are often inconsistent with long-term (i.e. years) responses, but are critical to understanding growth responses. We investigated carbon allocation in two full-sibling clones of loblolly pine under two levels of fertilizer application over four months in a greenhouse. Using monthly harvests of some trees and ecophysiological measurements throughout, we determined carbon allocation on a monthly scale. In response to fertilizer application, both clones reduced allocation belowground and increased allocation to foliage to some extent, increasing whole-canopy photosynthetic capacity. However, these changes in allocation were ephemeral. By the end of the experiment, root-shoot ratios were no longer significantly affected by fertilizer application. Clones had allocation patterns distinct from one another, with one allocating more belowground and the other allocating more to stem mass. While their overall growth responses to fertilizer application were similar, the physiological mechanisms that resulted in these responses were different between clones. Results of the two studies indicate that while fertilizer responses may not need to be included when testing clones for deployment, knowledge of the fertilizer responses of widely-deployed clones would offer forest managers opportunities to apply clone-specific precision-silvicultural systems to optimize growth rates and manage for a range of products. / Ph. D.

Shoots were selected in both interior and exterior canopy positions on 20-year-old 'Delicious' apple trees located at the VPI & SU Horticulture Farm orchard, Blacksburg, Va. The most recently unfolded leaf was tagged on April 28, May 12, and May 26, 1976. Shoot length was unaffected by canopy position but leaf number was greater on exterior shoots. One shoot from each canopy positions was detached for determination of net photosynthesis (Pn) and specific leaf weight (SLW) of tagged leaves on June 6, July 7, and August 4. Net photosynthesis and SLW of exterior leaves were greater than that of interior leaves. As leaf age increased, Pn tended to decrease while SLW increased. No significant correlation was found between SLW and Pn. Young container trees were placed under the canopy of the orchard trees and in a full sun location nearby. The most recently unfolded leaf was tagged on June 6, June 17, June 30, and July 14. Shoot length of the single stem tree was not affected by exposure, but leaf number was greater on sun trees. Net photosynthesis was determined on the same attached leaves at each time and was significantly higher for sun leaves than shade leaves. There were no differences in Pn as leaves aged. Specific leaf weight was determined once and was significantly higher for sun leaves. Maximum Pn rates were reached at approximately 13 klx for shade leaves while sun leaves had not reached maximum Pn at 27 klx. / Master of Science

Net photosynthesis (Pn) and photosynthate partitioning were compared between fruiting and deblossomed strawberry plants. Throughout a six-week fruiting cycle, Pn (leaf area basis), specific leaf weight (SLW), and chlorophyll content were determined at 7-day intervals for an early-formed leaf (old leaf) and for the most recently expanded leaf (young leaf) of fruiting and deblossomed day-neutral plants (cv. Tribute). During the fifth week of the fruiting cycle, Pn of the young leaf was higher for fruiting plants than for deblossomed plants. Pn of the old leaf was not different between treatments during any week. During weeks 4 and 5, the young leaf of the deblossomed plants had a higher SLW than that of fruiting plants; SLW of the old leaf was higher for deblossomed plants during weeks 4-6. The young leaf of the deblossomed plants had a higher chlorophyll content than that of fruiting plants during weeks 1 and 4. Chlorophyll content of the old leaf was higher for deblossomed plants during weeks 1, 2, and 4. There were no differences between treatments for stomatal conductance for CO₂ or dark respiration during any week of the fruiting cycle. In another experiment, deblossoming day-neutral strawberry plants (cv. Tribute) increased the amount of ¹⁴C translocated to the newly-emerging leaves 48 hrs after treatment with ¹⁴CO₂. During weeks 3-6 of the fruiting cycle, leaves of deblossomed plants had a greater total area, dry weight, and total non-structural carbohydrate (TNSC) content than leaves of fruiting plants. Pn on a whole-plant basis was higher for deblossomed plants than fruiting plants. This was largely due to the greater leaf area of the deblossomed plants, since total leaf area was highly correlated with Pn (whole plant basis). Pn (whole plant basis) was highly correlated with total dry weight and TNSC of plants in both treatments. Thus, deblossoming changed Pn and dry matter partitioning of strawberry plants. The additional leaf area and greater Pn rates (whole plant basis) obtained by deblossoming strawberry plants may result in increased yields during subsequent fruiting cycles. / Ph. D.

This PhD thesis presents results of a research focussed on the evolution of phototrophy in the bacterial order Rhodobacterales with a special regard to its haloalkaliphilic representatives. The photoheterotrophic bacterium Rhodobaca barguzinensis alga05 was used as an organism of choice. Its phylogeny, genome organization, and metabolic potential was characterized. The main result of the thesis is that phototrophy is a genuine trait among the haloalkaliphilic representatives of the Rhodobacter-Rhodobaca group inside the Rhodobacterales clade.

This thesis considers the implications of changes in the supply of resources for photosynthesis, with regard for modes of carbon acquisition employed by aquatic plants of the River Murray. Carbon supplies are inherently more variable for aquatic plants than for those in terrestrial environments, and variations are intensified for plants in semi-arid regions, where water may be limiting. In changeable environments the most successful species are likely to be those with flexible carbon-uptake mechanisms, able to accommodate variations in the supply of resources. Studies were made of plants associated with wetland habitats of the Murray, including Crassula helmsii, Potamogeton tricarinatus, P. crispus and Vallisneria americana. The aim was to elucidate the mechanisms of carbon uptake and assimilation employed, and to determine how flexibility in carbon uptake and/or assimilation physiology affect survival and distribution. Stable carbon isotopes were used to explore the dynamics of carbon uptake and assimilation, and fluorescence was used to identify pathways and photosynthetic capacity. The studies suggest that physiological flexibility is adaptive survival in changeable environments, but probably does not enhance the spread or dominance of these species. V. americana is a known bicarbonate-user, and it is shown here that it uses the Crassulacean Acid Metabolism (CAM) photosynthetic pathway under specific conditions (high light intensity near the leaf tips) concurrently with HCO[subscript]3 - uptake, while leaves deeper in the water continue to use the C[subscript]3 pathway, with CO₂ as the main carbon source. However, V. americana does not use CAM when under stress, such as exposure to high light and temperature. The diversity of carbon uptake and assimilation mechanisms in this species may explain its competitive ability in habitats associated with the Murray. In this way it is able to maximise use of light throughout the water column. In shallow, warm water, where leaves are parallel to the surface, CAM ability is likely to be induced along the length of the leaf, allowing maximal use of carbon and light. The amphibious C. helmsii is shown to use CAM on submergence, even where water levels fluctuate within 24 hours. This allows continued photosynthesis in habitats where level fluctuations prevent access to atmospheric CO₂. It appears that stable conditions are most favourable for growth and dispersal, and that the spread of C. helmsii is mainly by the aerial form. Carbon uptake by P. tricarinatus under field conditions is compared with that of P. crispus to demonstrate differences in productivity associated with aqueous bicarbonate and atmospheric CO₂ use. P. tricarinatus uses HCO[subscript]3 - uptake to promote growth toward the surface, so that CO₂ can be accessed by floating leaves. Atmospheric contact provides access to light and removes the limitation of aqueous diffusive resistance to CO₂, thereby increasing photosynthetic capacity above that provided by submerged leaves. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320380 / Thesis (Ph.D) -- University of Adelaide, School of Earth and Environmental Sciences, 2008

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This thesis considers the implications of changes in the supply of resources for photosynthesis, with regard for modes of carbon acquisition employed by aquatic plants of the River Murray. Carbon supplies are inherently more variable for aquatic plants than for those in terrestrial environments, and variations are intensified for plants in semi-arid regions, where water may be limiting. In changeable environments the most successful species are likely to be those with flexible carbon-uptake mechanisms, able to accommodate variations in the supply of resources. Studies were made of plants associated with wetland habitats of the Murray, including Crassula helmsii, Potamogeton tricarinatus, P. crispus and Vallisneria americana. The aim was to elucidate the mechanisms of carbon uptake and assimilation employed, and to determine how flexibility in carbon uptake and/or assimilation physiology affect survival and distribution. Stable carbon isotopes were used to explore the dynamics of carbon uptake and assimilation, and fluorescence was used to identify pathways and photosynthetic capacity. The studies suggest that physiological flexibility is adaptive survival in changeable environments, but probably does not enhance the spread or dominance of these species. V. americana is a known bicarbonate-user, and it is shown here that it uses the Crassulacean Acid Metabolism (CAM) photosynthetic pathway under specific conditions (high light intensity near the leaf tips) concurrently with HCO[subscript]3 - uptake, while leaves deeper in the water continue to use the C[subscript]3 pathway, with CO₂ as the main carbon source. However, V. americana does not use CAM when under stress, such as exposure to high light and temperature. The diversity of carbon uptake and assimilation mechanisms in this species may explain its competitive ability in habitats associated with the Murray. In this way it is able to maximise use of light throughout the water column. In shallow, warm water, where leaves are parallel to the surface, CAM ability is likely to be induced along the length of the leaf, allowing maximal use of carbon and light. The amphibious C. helmsii is shown to use CAM on submergence, even where water levels fluctuate within 24 hours. This allows continued photosynthesis in habitats where level fluctuations prevent access to atmospheric CO₂. It appears that stable conditions are most favourable for growth and dispersal, and that the spread of C. helmsii is mainly by the aerial form. Carbon uptake by P. tricarinatus under field conditions is compared with that of P. crispus to demonstrate differences in productivity associated with aqueous bicarbonate and atmospheric CO₂ use. P. tricarinatus uses HCO[subscript]3 - uptake to promote growth toward the surface, so that CO₂ can be accessed by floating leaves. Atmospheric contact provides access to light and removes the limitation of aqueous diffusive resistance to CO₂, thereby increasing photosynthetic capacity above that provided by submerged leaves. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320380 / Thesis (Ph.D) -- University of Adelaide, School of Earth and Environmental Sciences, 2008