Sökning: "seed-quality"

Visar resultat 1 - 5 av 6 avhandlingar innehållade ordet seed-quality.

1. 1. Reproductive patterns of birches (Betula spp.) in northern Sweden

   Författare :Stig-Olov Holm; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Reproduction; Betula; seed-quality; seed-set; pollination; pollen-limitation; pollen-competition; tree-line; environmental gradient; seed weight; seedling survival; Semudobia;

   Sammanfattning : The aim of this thesis was to study patterns of reproduction of Betula pendula and B. pubescens coll. along an altitudinal, coastal-inland, gradient in northern Sweden. The altitudinal variation was related to the distribution of the birch taxa along the gradient. LÄS MER

3. 2. Pollination processes - maternal and offspring performance

   Författare :Kristina Holmén Bränn; Kari Lehtilä; Pia Mutikainen; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Pollination; Sinapis arvensis; Brassica napus; Raphanus raphanistrum; Succisa pratensis; Evolution of flower size; Maternal plant responses; Resource allocation; Reproductive success; Terrestrial ecology; Terrestisk ekologi; Plant Ecology; växtekologi;

   Sammanfattning : Pollination is one of the most important factors determining the reproductive success of plants. This thesis examines processes associated to varying pollination, with focus on plant responses. The first aim was to examine the possibility and constraints for short-term evolution of flower size in Raphanus raphanistrum. LÄS MER

4. 3. Improved seed handling techniques for Juniperus polycarpos : implications for active restoration of degraded Juniper forests in Iran

   Författare :Abolfazl Daneshvar; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
   Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES;

   Sammanfattning : Juniperus polycarpos (K. Koch) is one of six native juniper forest tree species in Iran whose population size is declining continuously. The ultimate aim of the research presented in this thesis was to increase the regeneration potential of J. LÄS MER

5. 4. Costs of foraging in a dry tropical environment

   Författare :Mary Molokwu; Biologiska institutionen; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; foraging behavior; seasonality; predation risk; granivorous birds; food availability; water; temperature; savannah; dry tropics; energy; secondary compounds; diet selection;

   Sammanfattning : This study evaluates the costs associated with foraging for birds in a savannah woodland area in central Nigeria. Specifically, it looks at the following questions: 1) how does seasonal variability in food and water availability affect the value of resources to birds in dry environments? 2) Does proximity to water affect foraging decisions? What implication will this have in the management of savannah birds? 3) Are tropical birds mostly affected by metabolic or predation costs? 4) What factors affect diet selection in birds and how? 5) How are birds adapted to hot dry environments? I carried out experiments in the field and in an aviary and provided artificial food patches, consisting of feeding trays with seeds mixed in sand or pebbles (in the aviary study). LÄS MER

7. 5. Interplay Between Phospholipids and Digalactosyldiacylglycerol in Phosphate Limited Oats

   Författare :Henrik Tjellström; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; acyl chain order; Avena sativa; DGDG; digalactosyldiacylglycerol; oat; liquid order; phosphate; phospholipase; plasma membrane; stress;

   Sammanfattning : Phosphate is an essential nutrient. In most soils it is limiting, which has resulted in that phosphate is supplied as fertilizer to increase crop yield. Through evolution, plants have adapted several mechanisms to increase phosphate uptake from the soil and to household with acquired phosphate. LÄS MER