Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 6

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Although aerobiological data are frequently used as a fl owering sign in phenological research, airborne pollen counts are infl uenced by a number of factors affecting pollen curves. A study was made about the reproductive biology of birch and environmental factors infl uencing its pollen release and transport, in order to achieve a reliable interpretation of Betula pollen curves. Aerobiological data were recorded in 2002 and 2003 at two sites in NW Spain and phenological observations were carried out on 20 trees from four Betula populations (three Betula alba L. and one B. pendula Roth.). Pollen production was calculated for six Betula alba trees. Chilling and heat requirements for triggering development were calculated. Due to differences in the geographical location, budbreak and fl owering started fi rst in Betula pendula. The fl owering period lasted from 8-13 days. Reduced pollen output per anther and catkin in individual trees in 2003 prompted a marked decline in overall pollen production. Major differences observed in birch pollen curves were attributed to the infl uence both of weather conditions and pollen transport from areas where the fl owering occurs at a different time. Heat requirements calculated using phenological and aerobiological data were similar when the peak pollen- count date was used.
Botrytis cinerea is the cause of the most common disease in the Galician and Portuguese vineyards. Knowledge of the spore levels in the atmosphere of vineyards is a tool for forecasting models of the concentration of spores in order to adjust the phytosanitary treatments to real risk infection periods. The presented study was conducted in two vineyards, one located in Cenlle (Spain) and other in Amares (Portugal), from 2005-2007. A volumetric trap, model Lanzoni VPPS-2000, was used for the aerobiological study. Phenological observations were conducted on 20 vines of three grape varieties in Cenlle (Treixadura, Godello and Loureira) and in Amares (Trajadura, Loureiro and Pedernã), by using the BBCH scale. The highest total spore concentrations during the grapevine cycle were recorded in 2007 in both locations (Cenlle:16,145 spores; Amares:1,858 spores), and the lowest, in 2005 in Cenlle (1,700 spores) and in Amares (800 spores) in 2006. In Cenlle, the best adjusted model was an ARIMA (0,2,2), including the relative humidity four days earlier, while in Amares there was an ARIMA (1,2,3), considering the relative humidity three days earlier and rainfall two days earlier. The t-test showed no significant difference between observed and predicted data by the model.
The main characteristics of the Quercus pollination season were studied in 14 different localities of the Iberian Peninsula from 1992-2004. Results show that Quercus flowering season has tended to start earlier in recent years, probably due to the increased temperatures in the pre-flowering period, detected at study sites over the second half of the 20th century. A Growing Degree Days forecasting model was used, together with future meteorological data forecast using the Regional Climate Model developed by the Hadley Meteorological Centre, in order to determine the expected advance in the start of Quercus pollination in future years. At each study site, airborne pollen curves presented a similar pattern in all study years, with different peaks over the season attributable in many cases to the presence of several species. High pollen concentrations were recorded, particularly at Mediterranean sites. This study also proposes forecasting models to predict both daily pollen values and annual pollen emission. All models were externally validated using data for 2001 and 2004, with acceptable results. Finally, the impact of the highly-likely climate change on Iberian Quercus pollen concentration values was studied by applying RCM meteorological data for different future years, 2025, 2050, 2075 and 2099. Results indicate that under a doubled CO2 scenario at the end of the 21st century Quercus pollination season could start on average one month earlier and airborne pollen concentrations will increase by 50% with respect to current levels, with higher values in Mediterranean inland areas.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 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.