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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

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.
2

Odrůdová kvalita sladovnického ječmene / Varietal quality of malting barley

KADLECOVÁ, Helena January 2015 (has links)
By purchasing malting barley the quality is evaluated according to standards, techniques, laboratory methods and qualitative indicators, which are set by norm. Evaluation of quality of barleycorn as a material for producing malt is used for setting the price, observing changes of the quality during storing etc. There were evaluated qualitative indicators of 13 sorts of malting barley, which were bought by company ZZN Pelhřimov between 2010-2014 from farmers, agricaltural cooperatives and companies and also self-employed farmers from the region Vysočina. These sorts were represented by different number of samples in connection with bought-up amount and number of supplies of each sort. Weighted averages were counted from results. Average figures of results of analysis were compared with the national average. Research institute of brewer´s and orchardist a.s. in Brno deals with monitoring of quality of malting barley in the Czech Republic and it evaluates annually ca. 500 harvest samples which were received by producers from all regions in the Czech Republic. The quality of malting barley showed a big variability in all parameters across all types and also in particular years. Malting quality is influenced by many factors especially by course of weather in each particular year. Limiting parameter of quality by purchasing malting barley was N- substances content in barleycorn. Germination capacity seems to be the most stable from all parameters. Lower figures of germination capacity were found only by winter types in connection with longer period of ripening after harvest.
3

The evaluation of different technologies to restore old cultivated lands / Daniel Jacobus Taljaard

Taljaard, Daniel Jacobus January 2008 (has links)
Thesis (M.Sc. (Environmental Science and Management)--North-West University, Potchefstroom Campus, 2008.
4

The evaluation of different technologies to restore old cultivated lands / Daniel Jacobus Taljaard

Taljaard, Daniel Jacobus January 2008 (has links)
Thesis (M.Sc. (Environmental Science and Management)--North-West University, Potchefstroom Campus, 2008.
5

The evaluation of different technologies to restore old cultivated lands / Daniel Jacobus Taljaard

Taljaard, Daniel Jacobus January 2008 (has links)
Thesis (M.Sc. (Environmental Science and Management)--North-West University, Potchefstroom Campus, 2008.
6

Adansonia digitata and Adansonia gregorii fruit shells serve as a protection against high temperatures experienced during wildfires

Kempe, Andreas, Neinhuis, Christoph, Lautenschläger, Thea 09 June 2018 (has links) (PDF)
The thick and woody shell of the fruit of Adansonia species cannot be explained solely by adaptation to zoochory or hydrochory. Since the trunks of Adansonia possess a thick and fire-resistant bark and wildfires occur regularly in its habitat (savannah), we examined with the African Adanonia digitata and the Australian Adansonia gregorii whether the fruit offers protection against high heat typically experienced in wildfires. Heat-resistance tests were conducted by applying a simple heat test based on known temperature and temperature residence times occurring in savannah fires and complemented by tests to reveal the impact of heat on germination since long-term seed dormancy is known for Adansonia. Germination tests with acid treated and heat treated seeds were performed to establish if heat also increased germination rate as effectively as acid treatments have been found to do. Heat was found to increase germination rate, but not as effectively as treatment with acid, therefore fruits exposed to high temperatures experienced in wildfires may have a better chance of germination than fruits that were not exposed to wildfires. The ability of the investigated fruits to protect seeds from high temperatures suggests that wildfires may have played a role in the evolution of the hard-shell structure typically found in Adansonia.
7

Adansonia digitata and Adansonia gregorii fruit shells serve as a protection against high temperatures experienced during wildfires

Kempe, Andreas, Neinhuis, Christoph, Lautenschläger, Thea 09 June 2018 (has links)
The thick and woody shell of the fruit of Adansonia species cannot be explained solely by adaptation to zoochory or hydrochory. Since the trunks of Adansonia possess a thick and fire-resistant bark and wildfires occur regularly in its habitat (savannah), we examined with the African Adanonia digitata and the Australian Adansonia gregorii whether the fruit offers protection against high heat typically experienced in wildfires. Heat-resistance tests were conducted by applying a simple heat test based on known temperature and temperature residence times occurring in savannah fires and complemented by tests to reveal the impact of heat on germination since long-term seed dormancy is known for Adansonia. Germination tests with acid treated and heat treated seeds were performed to establish if heat also increased germination rate as effectively as acid treatments have been found to do. Heat was found to increase germination rate, but not as effectively as treatment with acid, therefore fruits exposed to high temperatures experienced in wildfires may have a better chance of germination than fruits that were not exposed to wildfires. The ability of the investigated fruits to protect seeds from high temperatures suggests that wildfires may have played a role in the evolution of the hard-shell structure typically found in Adansonia.

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