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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Crop Processing In The Early Bronze Age Houses Of Ikiztepe: Identification And Analysis Of Archaeobotanical Remains

Cilingir, Ceren 01 February 2009 (has links) (PDF)
ikiztepe is the largest excavated mound type settlement of prehistoric times in the Black Sea region in Turkey. It is located ca. 55 km northwest of Samsun, 7 km northwest of Bafra and is within the boundary of the present day village of Ikiztepe. The carbonised seeds and fruits secured from the occupation levels of ikiztepe houses dating from Chalcolithic to the Transition period are used to identify the crop processing activities conducted within the domestic units. Areas of fine sieving activity and the storage areas could be detected by the help of the analysis of the archaeobotanical materials. A comparison of the crop processing habits of the occupants of ikiztepe and other Early Bronze Age settlements in Anatolia is also made.
2

The effect of crop quality and pre-treatment on germination in Scots pine and Norway spruce seeds

Hilli, A. (Anu) 03 February 2009 (has links)
Abstract Weather conditions during the growing season are determining the size and quality of the Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seed crop in northern areas. Pathogens, fungi, and insects also have an effect on seed crops. The varying quality of seeds from forest stands and seed orchards does not full fill the germination requirements of tree nurseries. Multi-phase pre-treatment are therefore used in forest tree seed centres to improve seed lots quality. The main objectives of this study were to analyse long-term variation in the size and quality of Scots pine seed crops in Northern Finland. Determine the impact of fungal injuries on the structures of Norway spruce seeds. To detect changes in the germination capacity and rate of Norway spruce seeds during pre-treatment phases and to determine the impacts of short-term and long-term storage on the germination of treated seeds. The study found that in most years, regeneration of Scots pine in Northern Finland is limited by quantity as well as quality the seed crop. The long-term average of the Scots pine seed crop was 77seeds/m2 and the long-term average expected germination percentage was 61%. Aeciospores of the inlad spruce cone rust Chrysomyxa pirolata (Körnicke) Wint. were found to form inside Norway spruce seeds, destroying the nucellar layers and reducing germination of seeds. In general, the germination capacity and rate of Norway spruce seeds increased during pre-treatment phases. The germination capacity of seeds increased about 30% and the rate by more than 40% during pre-treatment. During long-term storage the germination capacity and rate of pre-treated Scots pine seeds were preserved better in frozen storage than in cool storage. It was found that pre-treated Scots pine forest stand seeds can be stored for several years in frozen conditions. The germination capacity and rate of pre-treated orchard seeds were effected significantly more than those from forest stands. It is therefore recommended that Scots pine seeds from orchards be stored without pre-treatment. The germination capacity and rate of treated Norway spruce seeds from orchards was not significantly different after one year of storage.
3

Spatial aspects of bumble bee (Bombus spp. Apidae) foraging in farm landscapes

Schaffer, M. J. January 1997 (has links)
Bumble bees (Bombus spp.: Apidae) are valuable pollinators of many crop and wildflower species. However, in some situations their potential is limited. Evaluation of, and management to improve bumble bee efficacy should include spatial information which is currently limited. Distance and direction determine the success of gene flow via pollen cross-over within and between plant populations at several scales. Studies of movement by bumble bees at large scales in semi-natural and intensively managed habitats are scarce. Few studies of bumble bee dispersal from the nest exist, particularly in relation to crops. At a small scale, directional rather than random movement between flowers has benefits for pollen flow. Results to date of directionality studies at small scales and their interpretation are inconsistent. The purpose of this thesis was to assess distances and directions moved by foraging bumble bees at a range of scales in two contrasting farm habitats in order to predict their pollination potential. A novel method was developed to mark automatically all the occupants of nests of bumble bees B. terrestris (L.) placed around a Lucerne seed crop Medicago sativa L. in New Zealand. Reobservation data from eight nests showed that of bumble bees which foraged within the crop, 81 % travelled ≤ 50 m and 56% ≤ 20 m from their nest. Results should be interpreted with extreme caution because fewer than 1 % of bumble bees marked at nests were reobserved in the crop. Because it was not established where the other 99% of the bumble bees went, foraging areas for nests could not be calculated as anticipated. Theories to explain the non-specificity of bumble bees to the crop include; resource depletion near nests, competition with honey bees in the crop, or an evolved strategy to disperse in order to minimise nest predation. Lucerne flowers contained a significantly lower concentration of sugar in nectar, and significantly fewer pollen grains than did those of purple loosestrife Lythrum salicaria L., a species on which bumble bees appeared to forage in preference Lucerne. The higher rewards offered by L. salicaria may have diverted bumble bees from the less-rewarding Lucerne crop. In a Norwegian meadow system, all foraging bouts by bumble bees B. lucorum (L.) within a patch of wood cranesbill flowers Geranium sylvaticum L. were random with respect to direction. This result is not consistent with predictions, based on optimal foraging theory, that movement should be directional to enable optimal pollen flow, and to avoid revisitation of just-emptied flowers by the pollinator. A medium-scale study of several bumble bee species moving between patches of northern wolfsbane Aconitum septentrionale Koelle in Norway revealed considerable loyalty by bumble bees to patches in which they were marked. In a different landscape-scale study (over 5 ha), several bumble bees exhibited a high degree of loyalty to areas in which they were marked (87% were reobserved ≤ 50 m from marking points). These restricted movement patterns are discussed in terms of potential pollen flow. Of 260 bumble bees marked, only five were recorded crossing between meadows, which could be a result of innate loyalty to small forage areas, an artefact of the sampling technique used, or forest boundaries acting as physical impediments to movement. In the future, spatial data of the type collected in this thesis will aid in the management of bumble bee populations to achieve both commercial and conservation goals. Spatial data can be applied to predict the optimal placement of artificially-reared nests, predict suitable isolation distances for pure seed crops, and aid in the positioning of supplementary forage sources and nest-site refuges.

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