Ambrosia pollen in the air of Lublin, Poland

Studies on Ambrosia pollen concentrations were carried out in Lublin in the period 1995–2004. The effects of a number of meteorological factors were analysed. In the first period of the study, the gravimetric method was used (1995–1999), while in the second period, the volumetric method was applied. The results show an increasing trend in the amount of airborne pollen. The Ambrosia pollen season in Lublin lasts from August to October. Over a period of 5 years, the highest number of pollen grains was recorded in September (53%), followed by August (44%) and October (3%). There were wide variations in annual totals. The annual total pollen counts was 167–1180 grains, with the peak value in 2002. Maximum daily pollen concentrations (56–312 pollen grains m⁻³) were recorded in the first half of August and in the first half of September. On the days when high Ambrosia pollen concentrations occurred, the temperature was above 21°C and the winds were mainly from the southeast, south and east. Maximum intradiurnal concentrations of pollen grains occurred in the afternoon hours. These results indicate, to some degree, that Ambrosia pollen is transported for long distances before descent.     

Structure of the nectary in Chaenomeles japonica (Thunb.) Lindl. ex Spach. in different stages of flowering with focus on nectar secretion

Protoplasma - Chaenomeles japonica is an attractive ornamental shrub flowering in spring. It is also a valuable source of nectar and pollen for entomofauna. The study was carried out to investigate...     

Structural features of <Emphasis Type="Italic">Rhododendron luteum</Emphasis> flower

The flower of Rhododendron luteum (L.) Sweet has a pentamerous structure with radial symmetry. The anthers filament surface is covered by dense non-glandular hairs to the half of the height. The tubular anther dehisces along creating two openings in the anther-sac walls and the viscous pollen is released through two splits along the anther lobes. The pistil is pentamerous and the axial channel is filled with a mucilaginous secretion product which is continuous with the exudate on the stigma surface. The stigmatic papillae are densely packed and their exudate is stained intensively red for carbohydrates, while pollen grains are stained positively for lipids. The five-locular ovary has isomerous carpels (syncarpous gynoecium) and the ovary surface is covered by numerous, densely-packed glandular and non-glandular hairs protecting the nectar against transpiration. Numerous ovules per locule occur with one integument and a thin-walled megasporiangium. In carpels, oil cells occur sporadically as solitary idioblasts, located around the vascular bundles. Transmitting tissue cells contain a large central, electron translucent vacuole, filling most of the cell containing dark osmiophilic bodies homogenous or granular in appearance.     

Application of the HYSPLIT model for birch pollen modelling in Poland

Aerobiologia - In this work, the HYSPLIT model was used to reproduce birch pollen concentrations in Poland for the years 2015 and 2016, where there was significant variation in terms of pollen...     

Forecasting model of <Emphasis Type="Italic">Corylus</Emphasis>, <Emphasis Type="Italic">Alnus</Emphasis>, and <Emphasis Type="Italic">Betula</Emphasis> pollen concentration levels using spatiotemporal correlation properties of pollen count

The aim of the study was to create and evaluate models for predicting high levels of daily pollen concentration of Corylus, Alnus, and Betula using a spatiotemporal correlation of pollen count. For each taxon, a high pollen count level was established according to the first allergy symptoms during exposure. The dataset was divided into a training set and a test set, using a stratified random split. For each taxon and city, the model was built using a random forest method. Corylus models performed poorly. However, the study revealed the possibility of predicting with substantial accuracy the occurrence of days with high pollen concentrations of Alnus and Betula using past pollen count data from monitoring sites. These results can be used for building (1) simpler models, which require data only from aerobiological monitoring sites, and (2) combined meteorological and aerobiological models for predicting high levels of pollen concentration.     

Warm and dry weather accelerates and elongates <Emphasis Type="Italic">Cladosporium</Emphasis> spore seasons in Poland

Temperature is the environmental factor that systematically changes for decades and, as in plants and animals, can significantly affect the growth and development of fungi, including the abundance of their sporulation. During the time of study (2010–2012), a rapid increase in air temperature was observed in Poland, which coincided with the substantial decrease in rainfall. The increase in annual mean temperatures at three monitoring sites of this study was 0.9 °C in Lublin and Rzeszow (east Poland) and 2.0 °C in Poznan (west Poland). Such warming of air masses was comparable to the average global air temperature rise in the period of 1880–2012 accounting for 0.85 °C, as reported by the Intergovernmental Panel on Climate Change. Moreover, there was a substantial decrease in rainfall, ranging from 32.7 % (Poznan) to 43.0 % (Rzeszow). We have demonstrated that under such conditions the mean and median values of total Cladosporium spore counts significantly increased and the spore seasons were greatly accelerated. Moreover, earlier start and later end of the season caused its extension, lasting from over 20 days in Rzeszow to around 60 days in Lublin and Poznan, when the cumulative amount of 5–95 % of spores was considered. The time of reaching the cumulative amount of 50 % of spores was up to 25 days earlier (difference in Poznan between 2010 and 2012). There was also a striking acceleration of the date of the maximal Cladosporium spore concentration per cubic metre of air (26 days for Lublin, 43 for Poznan and 56 for Rzeszow).     

The secretory glands of <Emphasis Type="Italic">Asphodelus aestivus</Emphasis> flower

Various secretory glands are observed on Asphodelus aestivus flower, a common geophyte of Mediterranean type ecosystem. The floral nectary has the form of individual slits between the gynecium carpels (septal nectary). The septal slits extend downwards to the ascidiate zone of the carpels. The nectar is secreted by the epidermal cells of the slits, which differentiate into epithelial cells. The latter contain numerous organelles, among which endoplasmic reticulum elements and golgi bodies predominate. Nectar secretion results in an expansion of the space between the septa. The nectar becomes discharged through small holes on the ovary wall. Six closely packed stamens surround the ovary and bear numerous papillae at their basis. These papillae are actually osmophores, i.e. secretory structures responsible for the manufacture, secretion and dispersion of terpenic scent. A mucilage gland (obturator) exists between the lateral ovule and the ovary septa, giving a positive reaction with Schiff’s reagent. This gland secretes a mucoproteinaceous product to nourish the pollen tube and to facilitate its penetration into the ovary.     

Spatial variations in the dynamics of the Alnus and Corylus pollen seasons in Poland

The objective of this study was to analyse the dynamics of the Alnus and Corylus pollen seasons in Poland with reference to spatial and seasonal differentiation. Aerobiological monitoring was performed in 10 cities, in 1994–2007. Five characteristics defining the pollen season were considered: 1. beginning and end dates of the season phases (5, 25, 50, 75, 95% of annual totals), 2. pollen season duration (90% method), 3. skewness and 4. kurtosis of airborne pollen curves, and 5. annual pollen totals. The beginning of the Corylus pollen season in Warsaw started on the 53rd day of a year. The Alnus pollen season started 9.5 days (SE = 1.4) later. The start of the season for both taxa was delayed by 3.3 (SE = 0.5) days for each 100 km towards the east. The Corylus pollen season lasted about 15 days longer than the Alnus season. Season duration for both taxa decreased towards the east by 3.5 days (SE = 0.7) and towards the north by 1.3 days (SE = 0.6) for each 100 km. Seasonal dynamics of both taxa are skewed to the right. In cities located west of Warsaw the dynamics are more skewed (except at Szczecin, Wroclaw). Asymmetry decreases towards the east by 0.16/100 km. Almost all kurtosis values of pollen-season dynamics were positive and higher for Alnus. Kurtosis values for both taxa increase together with delay of the pollen season beginning by 4% per day (p < 0.0001). Mean pollen total increases: for Corylus mainly towards the north (by 64%/100 km), for Alnus mainly towards the west (by 15%/100 km). Geographical location (longitude and latitude) determines: the start and duration of the pollen season, skewness of the pollen curve, and annual totals.     

Statistical techniques for modeling of <Emphasis Type="Italic">Corylus</Emphasis>, <Emphasis Type="Italic">Alnus</Emphasis>, and <Emphasis Type="Italic">Betula</Emphasis> pollen concentration in the air

Prediction of allergic pollen concentration is one of the most important goals of aerobiology. Past studies have used a broad range of modeling techniques; however, the results cannot be directly compared owing to the use of different datasets, validation methods, and evaluation metrics. The main aim of this study was to compare nine statistical modeling techniques using the same dataset. An additional goal was to assess the importance of predictors for the best model. Aerobiological data for Corylus, Alnus, and Betula pollen counts were obtained from nine cities in Poland and covered between five and 16 years of measurements. Meteorological data from the AGRI4CAST project were used as a predictor variables. The results of 243 final models (3 taxa \(\times\)  9 cities \(\times\) 9 techniques) were validated using a repeated k-fold cross-validation and compared using relative and absolute performance statistics. Afterward, the variable importance of predictors in the best models was calculated and compared. Simple models performed poorly. On the other hand, regression trees and rule-based models proved to be the most accurate for all of the taxa. Cumulative growing degree days proved to be the single most important predictor variable in the random forest models of Corylus, Alnus, and Betula. Finally, the study suggested potential improvements in aerobiological modeling, such as the application of robust cross-validation techniques and the use of gridded variables.