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Pollination Period (pollination + period)
Selected AbstractsRespiration and thermogenesis by cones of the Australian cycad Macrozamia machiniiFUNCTIONAL ECOLOGY, Issue 6 2004R. S. SEYMOUR Summary 1While cycads are often considered to be wind-pollinated, it is now clear that insects are pollen vectors in many species. This study addresses the role of thermogenesis in pollination biology of the dioecious cycad Macrozamia machinii P.I. Forster & D.L. Jones. 2The patterns of thermogenesis in intact male and female cones were assessed with thermometry and respirometry throughout the pollination period in the field. 3Thermogenic episodes in male cones occurred from about 17.00,00.00 h on successive evenings, in association with dehiscence of sporangia and presence of their pollinating weevils (Tranes sp.). 4Temperatures of the 167 g male cones rose ,6 °C above ambient, and mean rate of oxygen consumption peaked at 7·7 µmol s,1 (3·6 W). Regulation of male cone temperature was not evident, and thermogenesis of female cones was insignificant. 5Male cones probably heat to augment scent production and enhance weevil activity, including mating and egg-laying, but female cones may benefit from reduced visitation and freedom from damage by weevil larvae. Male cones may be sacrificial in providing the reward to the pollinators while the female cones are safeguarded. [source] Cone abortion in Pinus halepensis: the role of pollen quantity, tree size and cone locationOIKOS, Issue 1 2002Shirrinka Goubitz This study describes the seasonal patterns of seed and cone abortion in natural Pinus halepensis trees and assesses the effects of pollen quantity, tree size and cone location on seed and cone abortion. The cone-set ratio was similar to the expected value, based on literature on woody perennials. The seed-ovule ratio, however, was almost twice as high as its expected value. The investment in protective cone elements was high and did not vary with the seed-ovule ratio of a cone. Pollination factors influenced cone abortion, as indicated by the high abortion rate at the end of the pollination period. Furthermore, abortive cones had lower pollination rates and lower pollen loads than well developed cones. Effects of resource availability were assessed as effects of tree size and cone position on twigs. Small trees aborted more cones than big trees and cone abortion was higher in apical cones than in basal cones. Abortion in P. halepensis is selective, mediated by both pollen quantity and resource availability. The relative importance of pollen and resources is suggested to be flexible, probably varying between trees and years. The high seed-ovule ratio of P. halepensis is the result of high pollination rate and selective abortion. The selective abortion might be due to the high allocation to protective cone elements relative to the allocation to seeds. [source] Factors affecting pollination ecology of Quercus anemophilous species in north-west SpainBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2005F. J. RODRÍGUEZ-RAJO Pollination ecology of Quercus is influenced by meteorological, biotic and genetic factors. This study was undertaken to ascertain the effect induced by these factors on pollen production, release and dispersion. Aerobiological data have been used in recent years as phenological information, because the presence of pollen in the air is the result of flowering across a wide area. The onset of the Quercus pollen season and the atmospheric pollen concentrations during the pollination period in two localities of north-west Spain (Ourense and Santiago) were determined from 1993 to 2001. There were important variations in total annual pollen as a result of meteorological conditions, lenticular galls produced by Neuropterus on catkins and biennial genetic rhythms of pollen production. In order to determine the beginning of flowering, a thermal time model has been used. Chill requirements were around 800 chilling hours (CH) and heat requirements were 953 growth degree days (GDD in °C) in Santiago and 586 GDD in Ourense. Pollen in the air show positive correlation (99% significance) with daily thermal oscillation, maximum and minimum temperatures, and hours of sunshine. Regression analysis with previous days' pollen concentrations explained the high percentage of pollen concentration variability, as meteorological variables do not, on their own, explain pollen production and release. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society, 2005, 149, 283,297. [source] Quantification of group 5 grass pollen allergens in house dustCLINICAL & EXPERIMENTAL ALLERGY, Issue 11 2000B. Fahlbusch Background It is widely known and accepted that grass pollen is a major outdoor cause of hay fever. However, it is of virtual importance for grass pollen allergic patients with symptoms all the year round to know the concentration of grass pollen allergens in their homes. Objective The main objective of this study was to quantify the amount of grass pollen allergen in mass units (,g Phl p 5) in dust settled indoors and to detect the distribution of allergenic activity in different sampling locations of homes. Furthermore, we studied the seasonal fluctuation of allergen content in dust samples. Methods We adapted the two site binding assay for detection of group 5 grass pollen allergens in samples from randomly selected homes in Hamburg (n = 371), Erfurt (n = 396), Hettstedt (n = 353), Zerbst (n = 289) and Bitterfeld (n = 226), Germany. Dust samples were collected from floor of living room (LR), bedroom (BR) or children's room (CR) and mattress (MA) during period of June 1995 to August 1998. The amount of the major grass group 5 allergens was detected in ,g/g dust. Results Phl p 5 was detected in 67% of the samples analysed (n = 4760). The range was between undetectable (< 0.03 ,g/g dust) and 81 ,g/g dust. Phl p 5 levels were significantly higher in the dust from LR (geometric mean 0.117 ,g/g dust) or BR/CR floors (geometric mean 0.098 ,g/g dust) than in mattresses (geometric mean 0.043 ,g/g dust). We observed seasonal fluctuation of indoor Phl p 5 levels with peak in June but also annual differences. Thus Phl p 5 content indoors reflects also the different quantities of pollen counts of annual courses. During pollination period we found two times higher Phl p 5 levels (0.172 ,g/g dust, P < 0.001) than outside of grass pollination season (0.095 ,g/g dust). The indoor Phl p 5 levels outside of season seem to be independent of pollination before. We suppose that settled pollen grains or allergenic material from outdoor particles carried indoors via footwear and clothes accumulates in house dust. Conclusion Although we not known how the allergens in settled dust are equilibrated with those in the air, the considerable high level of Phl p 5 in indoor dust even during periods when no grass pollen is present in the atmosphere may be an important cause of pollen-allergy symptoms outside of season. [source] Exposure to grass pollen in EuropeCLINICAL & EXPERIMENTAL ALLERGY REVIEWS, Issue 1 2008S. JaegerArticle first published online: 7 APR 200 Summary Pooideae encompass both common wild and cultivated grasses, which are responsible for grass pollen exposure and sensitization in Europe. Across Europe, the pollination period of different members of this subfamily overlap and hayfever sufferers are therefore naturally exposed to a mixture of pollens from different grass species. Because of their morphological homology, Pooideae pollens are evaluated together in pollen counts and cannot be distinguished. Neither patients themselves, nor physicians can link the onset of hayfever symptoms to a specific grass species. [source] | |||||||||||||