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Visar resultat 1 - 5 av 143 avhandlingar som matchar ovanstående sökkriterier.

1. 1. The circadian clock in annuals and perennials : coordination of Growth with Environmental Rhythms

   Författare :Mikael Johansson; Maria E. Eriksson; Paul Devlin; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; circadian clock; arabidopsis; populus; Molecular biology; Molekylärbiologi; Plant biotechnology; Växtbioteknik; Plant physiology; Växtfysiologi; molekylärbiologi; Molecular Biology;

   Sammanfattning : Since the first signs of life on planet earth, organisms have had to adapt to the daily changes between light and dark, and high and low temperatures. This has led to the evolution of an endogenous time keeper, known as the circadian clock. LÄS MER

3. 2. Herbivores influence nutrient cycling and plant nutrient uptake : insights from tundra ecosystems

   Författare :Hélène Barthelemy; Olofsson Johan; Ellen Dorrepaal; Ann Milbau; Gough Laura; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Reindeer grazing; large herbivores; nutrient cycling; plant nutrient uptake; soil nutrient availability; arctic plant ecology; soil microbial communities; 15N stable isotopes; plant-soil interactions; plant quality; dung and urine.; Environmental Science; miljövetenskap; biology; biologi;

   Sammanfattning : Reindeer appear to have strong positive effects on plant productivity and nutrient cycling in strongly nutrient-limited ecosystems. While the direct effects of grazing on vegetation composition have been intensively studied, much less is known about the indirect effect of grazing on plant-soil interactions. LÄS MER

4. 3. Herbivory and plant community structure in a subarctic altitudinal gradient

   Författare :Jon Moen; Nancy Huntly; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; arctic and alpine vegetation; competition; exclosures; lemmings; plant defences; plant-plant interactions; Ranunculus glacialis; snow-bed; structuring factors; tall herb meadow; vertebrate grazing; voles;

   Sammanfattning : The object of this thesis was to study plant community structure, especially in relation to vertebrate herbivory, in an altitudinal gradient in the Fennoscandian mountain chain.A sowing experiment in a high alpine Ranunculus glacialis population showed that seeds germinated better in cleared microsites than under established individuals. LÄS MER

5. 4. Intramolecular isotope analysis reveals plant ecophysiological signals covering multiple timescales

   Författare :Thomas Wieloch; Jürgen Schleucher; Mats Nilsson; Gerd Gleixner; Lisa Wingate; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NMR spectroscopy; tree ring; isotope ratio; isotope effect; intramolecular 13C 12C signal; carbon allocation; acclimation; plant performance; climate reconstruction; plant ecophysiology;

   Sammanfattning : Our societies' wellbeing relies on stable and healthy environments. However, our current lifestyles, growth-oriented economic policies and the population explosion are leading to potentially catastrophic degradation of ecosystems and progressive disruption of food chains. LÄS MER

7. 5. Plant UDP-glucose Pyrophosphorylase : Function and Regulation

   Författare :Meng Meng; Leszek Kleczkowski; Javier Pozueta-Romero; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; UDP-glucose pyrophosphorylase; carbohydrate metabolism; in vivo regulation; T-DNA knockout; heterologous expression; isozyme; mutagenesis; kinetic property; oligomerization; Plant physiology; Växtfysiologi;

   Sammanfattning : UDP-glucose pyrophosphorylase (UGPase) is an important enzyme of carbohydrate metabolism in all living organisms. The main aim of this thesis was to investigate the function and regulation of plant UGP genes as well as the UGPase proteins. LÄS MER