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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

Faktory ovlivňující šíření dubu letního na výsypce po těžbě uhlí / Factors affecting oak spreading on post mining heaps

Janoušová, Ivana January 2013 (has links)
The study was conducted on spoil heap Podkrušnohorská (50 ř 14'09 S, 12 ř 39'05 V) near Sokolov. Several factors that influence the establishment of oak were studied: the distance from the source of diaspors, type of habitat (succession vs alder reclamation), position of seedling on the wave and impact of animal grazing. Four alder restoration areas and three spontaneous succession areas have been mapped with GPS equipment, the occurence of mature oaks, which could serve as a source of acornsg was also mapped on the dump and in surroundings. Most seedlings (657) were found in the succession and only 98 in alder reclamation, and the occurence in succession was statistically significantly more frequent. The number of seedlings from sources diaspors decreased, the longest distance was over 1300 meters. For three habitats (spontaneous succession, alder reclamation, open space with grass vegetation (Calamagrostis epigeios)) were planted 12 oak seedlings in fence and 12 seedlings outsider of the fence. Annual growth rate and survival of oak were evaluated using two-way ANOVA. Results showed that the area has a significant effect on the growth of oaks. In alder reclamation and the open area had a high mortality of seedlings and small increase, the fence does not have significant influence on these areas....
2

Paprastojo (Quercus robur L.) ir bekočio (Q. petraea [Matt.] Liebl.) ąžuolų hibridizacija, atsikūrimas ir poveikis dirvožemio mikrobiotai / Pedunculate (Quercus robur L.) and Sessile Oak (Q. petraea [Matt.] Liebl.) Hybridization, Regeneration and Effects on Soil Microbiota

Jurkštienė, Girmantė 18 November 2014 (has links)
Šiame moksliniame darbe nagrinėjama paprastojo (Quercus robur L.) ir bekočio (Q. petraea [Matt.] Liebl.) ąžuolų hibridizacija Trako miške (Alytaus raj.), bei su ja susiję ąžuolų pomiškio plitimo, lapijos nuokritų biocheminės sudėties bei įtakos dirvožemio mikrobiotai procesai. Šis darbas nuo kitų Europoje atliktų tyrimų išsiskiria savo specifika, kadangi tyrimų objektas apima bekočio ąžuolo arealo pakraštį. Nustatyta, kad tarprūšiniai hibridai Trako miške plito greičiau nei bekočiai. Trako miško motinmedžių ir jų palikuonių palyginamoji taksonominė analizė parodė, kad tarprūšinių paprastojo ir bekočio ąžuolų hibridų morfologinių lapų požymių variacija juvenaliniame amžiuje buvo didesnė nei vienos kurios tėvinių rūšių. Molekulinė-genetinė analizė patvirtino rūšinės priklausomybės nustatymo pagal morfologinius lapų požymius tinkamumą ir efektyvumą. Įrodyta, kad hibridizacijos procesams būdingas asimetrinio kryžminimosi pobūdis ir introgresijos procese dalyvauja ribotas individų skaičius. Vyrauja grįžtamasis kryžminimasis su viena iš tėvinių rūšių, šiuo atveju su bekočiu ąžuolu. Didesnė lignino koncentracija paprastojo ąžuolo lapuose sąlygojo mažesnį bakterijų ir mikroorganizmų, ypač mikromicetų, aktyvumą šio ąžuolo rizosferoje. Palyginus su paprastuoju ąžuolu, bekočio ir hibridinių ąžuolų lapų nuokritos ir rizosferos organinės medžiagos buvo intensyviau skaidomos. Todėl šių ąžuolų aplinkoje sąlygos plisti pomiškiui yra palankesnės negu po paprastaisiais ąžuolais. / This study analyzes hybridization of pedunculate (Quercus robur L.) and sessile (Q. petraea [Matt.] Liebl.) oak in forest Trakas (Alytus district), including the following processes related to hybridization: the prevalence of oak undergrowth, leaf litter fall and its biochemical composition, impact on soil microbiota. This study differs from other studies carried out in Europe by its specifics, since the research object is situated at the edge of the natural distribution of sessile oak. It was found the increase of the number of hybrid oaks in the undergrowth. A comparative taxonomic analysis of the parental trees of the Trakas forest showed that the variation of morphological traits of leaves of interspecific hybrids of pedunculate and sessile oaks was higher at juvenile age if compared with any paternal species. Molecular-genetic analysis confirmed suitability and effectiveness of the use of leaf morphological traits for species discrimination. Studies confirmed that hybridization process had a character of asymmetric crossings, a limited number of individuals participate in the introgression process. Backcross with one of the parental species – sessile oak prevails. The leaves litter fall of pedunculate oak was distinguished for a higher content of lignin, which determines decreased activeness of bacteria and, especially, micromicetes in the rhizosphere. The decomposition rate of leaves litter fall and organic compounds in rhizosphere under sessile and hybrid oaks were... [to full text]
3

Auswirkungen von Trockenheit und Entlaubung auf den Wasserhaushalt von Stiel- und Traubeneiche / Effects of Drought and Defoliation on Water Relations of Pedunculate and Sessile Oak

Gieger, Thomas 17 June 2002 (has links)
No description available.
4

Fiziološki aspekti otpornosti hrasta lužnjaka (Quercus robur L.), cera (Quercus cerris L.) i crne topole (Populus nigra L.) u uslovima vodnog deficita / Physiological aspects of resistance of common oak (Quercus robur L.), the Turkey oak (Quercus cerris L.) and black poplar (Populus nigra L.) under conditions of water deficit

Topić Mirjana 29 September 2015 (has links)
<p>&nbsp; &nbsp; U radu je ispitan uticaj vodnog deficita na fiziolo&scaron;ke osobine klonova crne topole i<br />populacija hrasta lužnjaka i cera, kao i mogućnost oporavka ovih biljaka nakon ponovnog uspostavljanja optimalnog vodnog režima. Cilj istraživanja je bio da se ukaže na potencijal ispitivanih genotipova topole i hrastova za opstanak u&nbsp; promenljivim uslovima životne sredine, u skladu sa aktuelnim klimatskim promenama koje uključuju smanjenje količine padavina i ograničenu dostupnost vode. Dobijeni rezultati su pokazali specifično variranje ispitivanih morfo-anatomskih, fiziolo&scaron;kih i biohemijskih parametara koje je zavisilo od momentalne vlažnosti zemlji&scaron;ta na primenjenom tretmanu (kontrola, su&scaron;a praćena oporavkom, konstantna su&scaron;a) i od genotipa biljke.<br />&nbsp; &nbsp; Negativan uticaj vodnog&nbsp; deficita na tretmanu konstantne su&scaron;e je u najmanjoj meri bio ispoljen na rastenje klona topole X/32, populaciju hrasta lužnjaka L1 i populaciju hrasta cera C1. Indeks tolerancije na stres izračunat na osnovu visine biljke (PHSI) takodje je potvrdio dobru morfolo&scaron;ku prilagodjenost pomenutih genotipova<br />na uslove su&scaron;e. Dobijene vrednosti indeksa stoma ukazuju da vodni status ispitivanih populacija hrastova nije bio naroĉito pogodjen vodnim deficitom na su&scaron;nim tretmanima.<br />&nbsp; &nbsp; Tretman konstantne su&scaron;e je u oba ogleda&nbsp; doveo do najvećeg smanjenja vrednosti<br />parametara razmene gasova kod skoro svih genotipova. S druge strane, primenjeni su&scaron;ni tretmani nisu uslovili smanjenje sadržaja fotosintetiĉkih pigmenata, kao ni parametra Fv/Fm, kod većine ispitivanih biljaka. U odnosu na kontrolu, sadržaj prolina u listovima ispitivanih biljaka na tretmanu konstantne su&scaron;e bio je&nbsp;&nbsp;&nbsp; znaĉajno povećan, a aktivnost enzima nitrat-reduktaze značajno smanjena, kod većine genotipova.<br />&nbsp; &nbsp; Genotipovi kod kojih u uslovima jakog vodnog deficita nije do&scaron;lo do značajne promene većine ispitivanih morfo-anatomskih, fiziolo&scaron;kih i biohemijskih parametara mogu biti od velike važnosti kad je u pitanju njihov odabir i upotreba za uspe&scaron;no po&scaron;umljavanje su&scaron;nih stani&scaron;ta, kojih će biti sve vi&scaron;e usled negativnog uticaja brojnih ekolo&scaron;kih činilaca nastalih kao posledica klimatskih promena.</p> / <p>The impact of water deficit and recovery on physiological features of the black poplar clones, as well as of the oaks populations were analyzed. The aim of this research was to indicate the potential of the studied genotypes for survival under changing environmental conditions, in accordance with current climate changes, which include the reduction in amount of rainfall and limited water availability. Obtained results have shown a specific variation of studied morpho-anatomical, physiological and biochemical parameters which depended on soil humidity on the applied treatment (control, drought followed by recovery and permanent drought), as well as on plant genotype.</p><p>Water deficit on permanent drought treatment had little negative effect on plant growth of poplar clone X/32, as well as oak populations L1 and C1. Plant height stress tolerance index also confirmed good morphological adaptation to drought of these genotypes. Stomatal index was not negatively affected by water deficit in oak plants.&nbsp;&nbsp;&nbsp;&nbsp; In both experiments, a permanent drought treatment led to the largest reduction in the values of gas exchange parameters in almost all genotypes.</p><p>On the other hand, concentration of&nbsp; photosynthetic pigments was not considerably decreased in plants exposed to water deficit, as well as the parameter Fv/Fm, in most examined plants. Compared to the control, the impact of permanent drought treatment&nbsp; on biochemical parameters was expected, in the most cases.&nbsp;&nbsp;&nbsp;&nbsp; Compared to the control, proline content in leaves of most examined genotypes was significantly increased on permanent drought treatment, while nitrate reductase activity was significantly decreased.</p><p>Examined genotypes exhibiting slight or no reduction in values of the most&nbsp; examined parameters during severe&nbsp; drought stress, could be used for afforestation in arid sites. Arid habitats appeared to be more numerous due to the effects of global climate changes.</p>

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