Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 51

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  Pinus nigra
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
The scale patterns of 6000 cones from one single tree of Pinus nigra Arn. have been examined. Apart from the main Fibonacci pattern with 8 and 13 parastichies, nine aberrant spiral patterns with Fibonacci-type sequences have been found. They are quite rare and occur with different frequencies. The parastichy quotient 8/13 of the prevalent pattern is very close to the golden ratio 0.618. In case of the black pine it appeared that the greater the deviation of the parastichy quotient m/n from 0.618, the rarer the pattern. Similar results obtained for the sample of 1506 cones collected from three individual trees of larch (Larix decidua Mill.) suggest a true correlation between the frequency of a pattern and the deviation of its parastichy quotient from the golden ratio.
Austrian pine (Pinus nigra Arn.), a species introduced into Polish forests, underwent dendroclimato- logical research using the response function method. The researchers analised the annual width increment against the climatic conditions of three populations of trees from the Nizina Wielkopolska and the Jura Krakowska. It was determined that among factors affecting the process of xylene cell formation in the analised trees, thermal and pluvial conditions had a relatively largeimpact. It is expressed in the coefficient of determination (R2) which had the following values: 44, 48 and 50%.
The potential of immature zygotic embryos to produce embryogenic tissue was tested using culture media differed in inorganic salt composition as well as plant growth regulator content. Explants cultured on DCR as well as MLV media gave the highest initiation percentages with maximum values of 8.8% (MLV) to 10.4% (DCR). Plant growth regulators content (standard or reduced) had no profound effect on embryogenic tissue initiation. Somatic embryo maturation as well as germination was dependent on the cell line and salt composition of the medium. Plantlet regeneration occurred in three cell lines out of five tested. During the maturation process profound changes occurred in the internal organisation of somatic embryos such differentiation of root meristem in precotyledonary somatic embryos and formation of provascular strands in cotyledonary somatic embryos.
Although intraspecies researches within the black pine (Pinus nigra Arnold) have a long tradition, the intraspecies taxonomy, classification and chorology are still unclear. Among the numerous reasons that have caused this situation the most important are: the absence of a study that would completely cover the whole range of this species, the impossibility of connection of results of the existing detailed studies of certain areas, and the high variability of traits which have been used so far. Since the characteristics of the molecular systematic techniques could make possible the research free of the mentioned shortages, the intention of this study was to determine the relationships among nine populations of black pine using the random amplified polymorphic DNA (RAPD). The obtained results were compared to the recent results of the morphological and anatomical analysis of the leaves of the same populations. The RAPD results clearly divided the Croatian populations from populations of Austria (subsp. nigra) and Turkey (subsp. pallasiana), while among Croatian populations, as in previous study, the existence of several groups (subsp. illyrica, subsp. dalmatica and transitional population between them) was noticed. It is assumed that the optimisations conducted in this study will finally make possible estimating the relationships on the level of the whole range of the black pine and the classification based on molecular traits that are probably less dependent on environmental influences than it has been the case with the characteristics mostly used so far.
The results of investigations on infection of P. nigra by Dothistroma septospora in seed plantation of the Miechów Forest District are presented in this paper. Disease symptoms were analized and the infection intensity depending on the needle age and location in the tree crown was estimated. The differences between individual progenies, and between individual plantation plots with respect to the disease intensity were also analized. The danger created for Pinus sylvestris by the inoculum of D. septospora accumulated on P. nigra was pointed out in the discussion.
W pracy przedstawiono wyniki badań dotyczące częstotliwości występowania na strzałach l'mus nigra raków drzewnych, których powstawanie przypisano Crumenulopsis sororia. Podano wymiary drzew porażonych w porównaniu z drzewami nie porażonymi oraz przeprowadzono wielostronny analizę miejsc rozwoju raków na strzałach.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 3 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.