Total Number Of Pollen Grains Research Articles

Differential Variability of Maize (Zea mays L.) Inbred Lines to Moisture-stress at Reproductive Stages and DNA Methylation Studies of Identified Contrasting Genotypes under Moisture-Stress Conditions

An investigation was undertaken to assess the effect of moisture stress during the reproductive initiation stage on the quality and quantity of pollen grains produced in eight inbred lines (UASBM22, UASBM13, UASBM09, UASBM11, UASBM06, UASBM14, UASBM02 and UASBM10) under greenhouse conditions in three blocks viz., well-watered, stress I (for 21 days from 28 days after sowing) and stress II (for 22 days from 32 days after sowing). Moisture stress significantly affected the number of pollen grains per anther and other plant growth-related traits. The moisture stress effect was not uniform across inbred lines. The inbred lines UASBM22, UASBM13, UASBM09 and UASBM11 recorded a significant reduction in the total number of pollen grains per anther and an increase in pollen sterility while in inbred lines, UASBM06, UASBM14, UASBM02 and UASBM10, the moisture stress effect was not significant. The changes in the DNA methylation pattern in leaves and immature anthers under moisture stress of the contrasting inbred lines (UASBM06 and UASBM13) were studied through methylation- sensitive random amplification polymorphism. An increase in total DNA methylation level in both leaves and anthers was observed in drought tolerant inbred line, UASBM06 under stress while the increase was only in the leaves of the susceptible inbred line UASBM13. Leaves and anthers of UASBM06 showed hypermethylation compared to UASBM13 in moisture-stress conditions. In maize, increased DNA methylation seems to be an important mechanism associated with drought responses which probably regulates the methylation-sensitive gene expression and acclimation responses in maize.

Melissopalynological analysis of Apis honey from northern districts of West Bengal

The assessment of botanical origin of honey in northern districts of West Bengal, viz. Coochbehar, Jalpaiguri and Alipurduar districts through melissopalynological analysis is the focus of this study. Ten different honey samples were analysed, from which 78 different pollen taxa representing 34 different plant families have been detected. Asteraceae, Brassicaceae and Fabaceae were the most frequently encountered families. Asteraceae had highest number of representative pollen types (14 types) followed by Fabaceae (11 types). Seven honey samples were recorded as unifloral honey and three were multifloral honey. Litchi chinensis was found as a predominant pollen in two samples, whereas Brassica sp., Canna indica, Leucas aspera, Mimosa pudica and Rosa sp. were the other predominant pollen taxa. In multifloral honey samples Brassica sp. was found to have a higher frequency. Honey samples collected from regions with close proximity during the same season showed a higher similarity index. All the honey samples were poor in honey dew elements (HDEs) having HDE/P ratio (P = total number of pollen grains) of 0.000 to 0.056. The absolute pollen count (APC) varied from 7500 to 696 000 pollen/10 g honey. High variation in pollen spectra with less preference to a particular bee forage in summer honey samples may indicate the onset of dearth period.

Taste for pollen comes in different shapes: Consumption by tadpoles from three divergent ecomorphotypes

AbstractPollen is a nutritive resource, but its role in aquatic food webs is little studied. Successful pollen acquisition may require behavioral adaptations for tadpoles with certain morphologies; however, pollen coats are hard to break to enable content assimilation. We investigated the consumption of pollen by tadpoles from three ecomorphotypes adapted to feed on the surface (neustonic), the water column (nektonic) and the bottom (benthic). We sampled three developmental stage ranges at both wet and dry seasons at a site in southeastern Brazil. We analyzed the pollen content and coat‐breaking level in three sections of tadpole guts and in their feces. We compared pollen composition in tadpole guts among groups based on species and developmental stages and between seasons. We also compared the total number of pollen grains and proportion of broken grains (as a surrogate for digestion capacity) in the guts among species, developmental stages, and between seasons. Ecomorphotype, developmental stage, and season influenced both composition and quantity of pollen consumed. Neustonic tadpoles in general consumed a greater amount of pollen grains and broke them faster, compared to the other ecomorphotypes. Tadpoles showed some variation in the amount of pollen consumed among developmental stages, which interacted with species, but developmental stages of the same species did not differ. Pollen consumption only varied between seasons for the nektonic tadpoles, being greater in the dry season. The high nutritive value of pollen is likely to make consumption by tadpoles rewarding and has an important effect in aquatic food webs, reinforcing the importance of conserving riparian habitats and their vegetation.

THE INFLUENCE OF VEGETAL EXTRACTS AND NANOSTRUCTURED MIXTURES ON GRAPEVINE POLLEN GRAINS

Pesticides, plant bio-stimulants and chemical fertilizers used in intensified viticulture affects negatively the viability of the plants pollen causing relevant economic losses to viticulturists. Given these conditions, we aimed to identify the environmentally friendly phytosanitary treatments which does not negatively affect the evolution of pollen grains. The experiment took place in the greenhouse on 120 grapevine plants from the genotypes Feteasca alba 97 St., Feteasca regala 72 St., Feteasca neagra 6 St., Cabernet Sauvignon 131 St., 30 plants/genotype. These have been treated to combat the Plasmopara viticola and Uncinula necator pathogens with pesticides, biological products, plant extract and nanostructured mixture. The studied genotypes reacted differently regarding the evolution of the viability of pollen grains, the average pollen grains size and the total number of pollen grains. The best results have been registered at F. regala 72 St. (the viability was significantly improved at plants treated with plant extract and those with nanostructured mixture and the highest number of pollen grains was recorded at the plants treated with nanostructured mixture).

CLUSTER COMPOSITION OF POLLEN PARTICLES OF ANEMOPHILIC PLANTS ENTERING ATMOSPHERE

A study is made on pollen emission into atmosphere of 21 species of anemophilous plants ( Betula divaricata Ledeb., Betula costata Trautv., Betula davurica Pall., Betula fruticosa Pall., Ulmus japonica (Rehd.)Sarg., Salix acutifolia Willd., Salix cinerea L., Salix purpurea L., Salix rosmarinifolia L., Alnus glutinosa (L.) Gaertn., Poa alpina L., Arrhenatherum elatius (L.) J. Presl & C. Presl, Briza maxima L., Deschampsia cespitosa (L.) P. Beauv., Urtica urens L., Carex altaica (Gorodkov) V.I. Krecz., Carex pallescens L., Carex flacca Schreb., Carex vesicaria L., Carex diluta M. Bieb., Plantago lanceolata L.), exposed by the Central Siberian Botanical Garden, SB RAS. These plants are widely spread over the territory of the Russian Federation and produce great amounts of allergenic pollen. The proportion of clusters of two or more pollen grains from the total number of pollen particles entering the atmosphere during the flowering periods of these plant species is estimated. It was shown that such clusters in significant quantities were formed in all series of experiments. At the same time, the proportion of pollen grains in their composition could reach 95% of the total number of pollen grains entering the atmosphere.

Factors Affecting the Number of Pollen Grains per Male Strobilus in Japanese Cedar (Cryptomeria japonica).

Japanese cedar (Cryptomeria japonica) is the most important timber species in Japan; however, its pollen is the primary cause of pollinosis in Japan. The total number of pollen grains produced by a single tree is determined by the number of male strobili (male flowers) and the number of pollen grains per male strobilus. While the number of male strobili is a visible and well-investigated trait, little is known about the number of pollen grains per male strobilus. We hypothesized that genetic and environmental factors affect the pollen number per male strobilus and explored the factors that affect pollen production and genetic variation among clones. We counted pollen numbers of 523 male strobili from 26 clones using a cell counter method that we recently developed. Piecewise Structural Equation Modeling (pSEM) revealed that the pollen number is mostly affected by genetic variation, male strobilus weight, and pollen size. Although we collected samples from locations with different environmental conditions, statistical modeling succeeded in predicting pollen numbers for different clones sampled from branches facing different directions. Comparison of predicted pollen numbers revealed that they varied >3-fold among the 26 clones. The determination of the factors affecting pollen number and a precise evaluation of genetic variation will contribute to breeding strategies to counter pollinosis. Furthermore, the combination of our efficient counting method and statistical modeling will provide a powerful tool not only for Japanese cedar but also for other plant species.

Estimation of pollen counts from light scattering intensity when sampling multiple pollen taxa – establishment of an automated multi-taxa pollen counting estimation system (AME system)

Abstract. Laser optics have long been used in pollen counting systems. To clarify the limitations and potential new applications of laser optics for automatic pollen counting and discrimination, we determined the light scattering patterns of various pollen types, tracked temporal changes in these distributions, and introduced a new theory for automatic pollen discrimination. Our experimental results indicate that different pollen types often have different light scattering characteristics, as previous research has suggested. Our results also show that light scattering distributions did not undergo significant temporal changes. Further, we show that the concentration of two different types of pollen could be estimated separately from the total number of pollen grains by fitting the light scattering data to a probability density curve. These findings should help realize a fast and simple automatic pollen monitoring system.

Honey yield conditions and characteristics of honeys in the south of the Far East of Russia

The article presents the characteristics of honey yield conditions and the quality of honey in the south of the Far East of Russia. The intensity of nectar production by plants in the active period of the beekeeping season is determined. The quality of the produced honey is estimated. The dominant honey plants in different seasons of the year have been established. The melliferous vegetation is rich and diverse and it allows to obtain the yield of marketable honey up to 61.6 kg per one bee colony during the research period. The main honey plant of Primorsky Krai is Tilia L. Its pollen contribution can reach 86.7% of the total number of pollen grains in the honey. Moreover, it is present in almost all honey samples. Among the secondary honey plants, the most valuable are Lespedeza bicolor Turcz., Fagopyrum esculentum Moench., species of genus Polygonum L. and of the Araliaceae family. Honey gathered at the same time in various areas of the region differs in pollen content of dominant honey plants significantly. Pollen of endemic plants are present in the honey samples, and it makes it possible to identify “Primorsky Honey” as highly reliable.

STUDY OF MELLIFEROUS PLANTS VISITED BY THE WORKER HONEYBEE, APIS MELLIFERA INTERMISSA IN BOUMERDES, ALGERIA

This work allows to establish a list of melliferous plants visited by the worker bee, Apis mellifera intermissa in Boumerdes through melissopalynological analysis. Eight samples of honey were collected in summer from different regions of Boumerdes province in Algeria: Mizrana (H1), Tizéruine (H2), Tagdempt (H3), Sherraba (H4), Baghlia (H5), Boudouaou (H6), Sidi Daoud (H7) and Si Mustapha (H8). For the analysis, we adopted the classical method of Louveaux et al., (1970). The results obtained showed that the melissopalynological analysis indicated the pollen grains of Eucalyptus were numerous as more than 45% of the pollen in six (6) of the eight samples of Boumerdes (H1, H2, H3, H4, H7 and H8). The pollen of Hedysarum coronarium was dominant in the sample H5 (67.60%). In seven samples honey recognized multifloral by beekeepers, Eucalyptus and Citrus taxa were respectively super represented and underrepresented in the honey H7 (87.46%) and H6 (19.80%). Thus, the number of taxa listed in the honeys studied varies from 14 to 19. The total number of pollen grains counted for the 8 samples varied from 646 to 3580.

Influence of high temperature on the reproductive biology of dry edible bean (Phaseolus vulgaris L.)

ABSTRACT: The aim of this study was to investigate the effect of heat stress on 12 bean genotypes through the analysis of their reproductive biology in terms of flowering, pollen viability, meiotic behavior, and production. Plants were grown in a climate chamber at 25-20 °C (day and night) and at a high temperature treatment 37-26 °C (day and night) from the vegetative (V4) development stage to physiological maturity. The experimental design was 2 × 12 factorial arrangement with six replications and the factors consisted of heat treatments and genotypes. In three replications, the number of newly opened flowers was checked daily. At physiological maturity, the following traits were evaluated: percentage of pod set, number of pods, number of viable seeds, number of aborted seeds, 100 seed weight, and seed yield (g per plant). The other three replications were used to collect flowers to create slides to study viability of the pollen grain and analyze the meiotic behavior. The heat treatment factor significantly affected the following traits: total number of pollen grains, number of flowers, number of pods, pod set, number of viable seeds, 100 seed weight, and seed yield. The raised temperature reduced these variables, except for percentage of pod set, and increased meiotic irregularities. The mean values regarding seed yield were 16.39 g per plant for the control treatment and 7.46 g per plant under high temperature. IAC Imperador, FT Nobre, Perola, BRS Estilo, and IAC Diplomata stood out for higher bean seed yield under increased temperature.

Quantitative and qualitative analysis of sunflower pollen (<i>Helianthus</i> L.) and it’s use in breeding work

Background. In breeding work, it is necessary to take into account such an important feature as male sterility of the hybrids obtained. If a plant has visually visible anthers and pollen, the quality of the pollen grains themselves may be low. It is necessary to carry out not only a visual analysis, but also a cytological study of pollen in order to properly assess the reproductive potential of plants.Materials and methods. Wild species, some cultivars, lines and hybrids of sunflower from the collection of the N. I. Vavilov All-Russian Institute of Plant Genetic Resources were taken as objects of research. The plants were grown on the fields of Kuban Experiment Station. Pollen was collected from preinsulated inflorescences, fixed in FAA solution and stained with acetocarmine. The ratio of fertile pollen grains to the total number of pollen grains (in %) was calculated, the diameter of the pollen grains was measured, and variability curves were drawn.Results. Mature pollen grains in sunflower are rounded, tricolpate-poral, threecelled; the average pollen diameter in cultivated sunflower is 28–32 μm; in wild species, the range is from 20– 22 μm to 32–34 μm. All accessions were divided into three groups. Fertile: high level of fertility (75–99%) and low morphological heterogeneity of pollen; the variation curve for the average diameter was characterized by one distinct peak. Most of the studied accessions were included here: cultivars, most of the lines and some of the wild species. Semi-fertile: the number of well-stained pollen grains is below 75%; there are differences in the degree of staining and size of the pollen; the variation curve had additional peaks. This group included some of the lines, hybrids and wild species. The greatest morphological heterogeneity was observed in the group of perennial interspecific hybrids. Sterile: pollen grains were absent or were observed very sporadically.Conclusion. To assess the fertility of plants, it is important not only to determine the degree of staining in pollen grains, but also to rank them by diameter and construct variation curves to reveal morphological heterogeneity of pollen.

Late Holocene Pollen Record of Environmental Changes in Karimata Strait, Sunda Shelf Region

DOI: 10.17014/ijog.6.1.41-55Pollen analysis has been conducted on a 90 cm gravity core taken from the Karimata Strait to reveal pollen facies in marine sediment and Late Holocene environmental changes in the central Sunda Shelf region. The core site is at 32 m water depth and located about 170 km northwest of Bangka Island, Indonesia. Ten samples were collected at 10 cm intervals through the core. The total number of pollen grains counted in the samples varies between very low (<50 grains) to abundant (>200 grains). High frequencies (50 - 70%) of mangrove pollen are found at 90 to 40 cm indicating that pollen facies in offshore marine sediment may be comparable with those in mangrove forest floor sediment. The core site has been in a neritic environment since its early deposition ca. 1,800 yr B.P. (~150 A.D.) when mangroves vastly grew on the tidal flats of the surrounding islands and they persisted to ca. 700 yr B.P. (~1,250 A.D.). In the middle of this period, a catastrophic event speculatively due to the 535 A.D. Krakatau eruption might have responsible for the decrease of mangroves and the disappearance of benthic foraminifers. The deposition of silicious materials (tephra) due to this eruption might have provided an opportunity for benthic foraminifers to increase their population subsequently. From ca. 700 yr B.P. (~1,250 A.D.) mangroves declined, as indicated by lower frequencies of pollen grain in samples from 30 cm deep upward. It occurred simultaneously with the deposition of coarser sediment and the increase of benthic foraminifer abundance. Interplay of anthropogenic activities, strengthening ENSO cycle, and lowering erosion base level might have been responsible for these environmental changes.

КЛАСТЕРНЫЙ СОСТАВ ПЫЛЬЦЕВЫХ ЧАСТИЦ АТМОСФЕРЫ В ПЕРИОД ЦВЕТЕНИЯ АНЕМОФИЛЬНЫХ РАСТЕНИЙ

A study is made on pollen emission into atmosphere of 12 species of anemophilous plants (Betula fusca Pall. ex Georgi, Betula pubescens Ehrh., Ulmus pumila L., Corylus americana Marsh., Corylus avellana L., Stipa pennata L., Poa nemoralis L., Achnatherum splendens (Trin.) Nevski, Panicum virgatum L., Lolium perenne L., Avena sativa L., Setaria maximowiczii Tzvelev & Prob.), exposed by the Central Siberian Botanical Garden, SB RAS. These plants are widely spread over the territory of the Russian Federation and produce great amounts of allergenic pollen. Estimated is the share of clusters of two and more pollen grains in the total number of pollen particles, entering the atmosphere upon blooming of plants of a given species. It is shown that although the anemophilous plants display morphological properties, that prevent the formation of clusters, substantial number of such clusters is recorded in all experimental series. In this case, the share of pollen grains could exceed 50% of the total number of pollen grains, entering the atmosphere.

Volumetric analysis of airborne pollen grains in the city of Uşak, Turkey

Airborne pollen in Usak, a province in Turkey, was studied for two years (from 1 February 2014 to 31 January 2016) using the volumetric method and the most recent pollen data of the region were obtained. During the study, 23,915 pollen grains were detected. The pollens detected belonged to 53 taxa. Of the 53 taxa, 28 were woody and 25 were herbaceous. Of the pollen grains detected, 86% (20,565 pollen grains) were from woody plants, 4.74% (1133 pollen grains) belonged to Poaceae, and 8.65% (2071 pollen grains) were from other herbaceous plants, whereas 0.61% (146 pollen grains) were unidentified pollen grains. Of the woody taxa, those whose pollen grains comprised more than 1% each of the total number of pollen grains during the study were Quercus (32.60%), Pinaceae (31.96%), Cupressaceae/Taxaceae (10.22%), Fraxinus (5.47%), and Platanus (1.12%), whereas of the herbaceous taxa, those whose pollen grains comprised more than 1% each of the total number of pollen grains were Poaceae (4.74%), Amaranthaceae (1.82%), Plantago (1.59%), and Rumex (1.18%). In the two-year period, the highest airborne pollen concentrations were recorded in May (47.30%), followed by April (27.64%) and June (10.47%). The results obtained in the study indicated that the dominant airborne pollen types detected in Usak generally had allergenic effects at moderate or high levels and that these taxa reached the highest amount in May.

Segregation and Heritability of Male Sterility in Populations Derived from Progeny of Satsuma Mandarin.

Male sterility derived from Satsuma mandarin (Citrus unshiu) has been used in Japanese citrus breeding programs to obtain seedless cultivars, which is a desirable trait for consumers. Male sterility has often been evaluated by anther development or pollen fertility; however, the inheritance and heritability of male sterility derived from Satsuma is poorly understood. In this study, we investigated the mode of inheritance and broad-sense heritability of male sterility derived from Satsuma. Initially, we evaluated the total number of pollen grains per anther and apparent pollen fertility, as indicated by lactophenol blue staining, in 15 citrus cultivars and selections to understand the male sterility of Satsuma. The results indicated that male sterility was primarily caused by decreased number of pollen grains per anther in progeny of Satsuma. We also evaluated these traits in three F1 populations (hyuganatsu × ‘Okitsu No. 56’, ‘Okitsu No. 46’ × ‘Okitsu No. 56’ and ‘Okitsu No. 46’ × ‘Kara’), of which the parents are derived from Satsuma. Individuals in these populations showed strong segregation for number of pollen grains per anther. The apparent fertility of pollen also showed segregation but was almost constant at 70%–90%. The estimated broad-sense heritability for the number of pollen grains per anther was as high as 0.898 in the ‘Okitsu No. 46’ × ‘Okitsu No. 56’ and ‘Okitsu No. 46’ × ‘Kara’ populations. These results indicated that the number of pollen grains per anther primarily determined male sterility among progeny of Satsuma, and this trait was inherited by the progeny. Development of DNA markers closely linked to male sterility using the F1 populations of ‘Okitsu No. 46’ × ‘Okitsu No. 56’ and ‘Okitsu No. 46’ × ‘Kara’ is expected to contribute to the breeding of novel seedless citrus cultivars.

The structure and robustness of nocturnal Lepidopteran pollen‐transfer networks in a Biodiversity Hotspot

Abstract The role of nocturnal moths within plant‐pollinator networks is poorly understood but could be important in the context of declining biodiversity and the ecosystem services they provide. For the first time, this study examined the role of moths as pollen vectors in the Mediterranean Biodiversity Hotspot. Light traps were used to sample moths in SW Portugal in 2010. The pollen on moth head parts was collected, identified, and counted to construct a nocturnal pollen‐transfer and flower‐visitor network. A total of 257 moths belonging to 95 species were captured in 11 trapping sessions in 2010; 196 moths (76%) carried pollen and the total number of pollen grains counted and identified was 9064. The pollen‐transfer network exhibited a high degree of selectivity (H2′) but low robustness when the most‐to‐least connected plants were made extinct in the network. The flower‐visitor network (based on the incidences of interactions by individual moths), however, exhibited high linkage density and was generally more robust to simulated plant or moth extinction. Including nocturnal moths in plant–pollinator networks will provide a better understanding of their robustness to species extinctions due to environmental change as well as the impacts on ecosystem structure and functioning. Nocturnal pollen–transfer networks could be developed for identifying key species for targeted conservation.

English

The lack of a reliable test to evaluate pollen viability in species of the genus Manihot is one of the primary limitations for cassava genetic improvement. Thus, the objective of the present study was to apply aniline blue stain to observing pollen tubes development in different Manihot Mill. species, in order to estimate the crossability, pollen germination time, pollen tube size and pollen longevity. Pollen grains from 2 accessions of the cultivated species M. esculenta spp. esculenta and 4 accessions of 3 wild species (M. esculenta ssp. flabellifolia (Pohl) Cif, M. anomala Pohl, and M. irwinii D. J. Roger and Appan) were used. To visualize the pollen tubes, pollinated stigmas was deposited on a glass slide with 3 drops of aniline blue stain and transferred to an optical fluorescence microscope, where they were visualized and photographed using the 10x ocular lens. The pollen crossability rate was estimated by the percentage of germinated pollen, with well-developed pollen tubes in relation to the total number of pollen grains counted per stigma. The experimental design was entirely random with 3 repetitions, each repetition consisting of 100 pollen grains. In addition to the estimation of crossability, the germination time after pollination, pollen tube size, and pollen longevity were also determined to the accession FLA 029V-01. Significant difference was observed between the crossings. Pollen tubes developed after 45 min of contact between the pollen and the stigma. The average pollen tube size 24 h after pollination was 2.9 mm. The studies examining pollen longevity showed that germination did not occur when the pollen grains were evaluated 24 h after anthesis. Thus, the use of aniline blue stain can be considered an effective method for observing pollen tubes development and studying the pollen morphology, longevity, viability and Manihot crossability.   Key words: Cassava, genetic resources, pre-breeding.

Results of pollen monitoring and features of seasonal allergic rhinitis in Samara

Background. The objective was to study the taxonomic diversity of the concentration of pollen, its changes and peculiarities of the course of seasonal allergic rhinitis in Samara city. Methods. Pollen was located with gravimetric method on the glass, covered with a special mixture. Clinical and allergological examination conducted among 775 children aged from 5 to 18 years and 692 adults with symptoms of rhinitis. Results. Registered three periods of increase of concentration of pollen: spring period, summer period and summer-autumn period. The major taxa in the spring was pollen Populus - 49% and Betula - 27% during this period. In the summer period dominated pollen was Pinus - 37%, Poaceae - 28% and Betula - 22%. In summer-autumn period prevailed pollen grains Ambrosia - 63% and Artemisia - 10%, of the total number of pollen grains for this period. Clinical and allergological studies have shown that the proportion of patients with seasonal allergic rhinitis is 78% among the total number of patients with allergic rhinitis. Isolated form of seasonal allergic rhinitis was diagnosed in 22% of children and in 20% of adults. Patients of this group are allergic to pollen, weeds and compositae revealed in 68%, trees - 20%, cereals - 12% of cases. Conclusion. Qualitative and quantitative composition of aeropalynologic spectrum was established and showed the peculiarities of the course of seasonal allergic rhinitis in Samara city.

Pollen production pattern in the capitulum of the cultivated sunflower (Helianthus annuus L.)

The intra-plant pollen production in cultivated sunflower (Helianthus annuus L.) was quali- and quantitatively studied. Two modern self-pollinated, high oleic sunflower hybrids were grown during two consecutive seasons: 2009 in three planting dates, and 2010 in two planting dates. Two cross-pollinated varieties of sunflower, Hopi and Havasupai, were also studied to determine if an anomalous intracapitulum pollen gradient observed in preliminary studies could be a remnant character inherited from primitive genotypes. Pollen grains per flower (PGF), anther volume (AV), pollen grain volume (PGV) and pollen viability (PV) were measured in three capitulum sectors, external (ES), middle (MS) and internal (IS). At harvest, fully developed fruits (FDF) and incompletely developed fruits (IDF) per capitulum sector were counted. Based on seasonal averages of hybrids and planting dates, the capitulum IS showed the highest PGF number (40864 ± 6519) followed by the MS (35243 ± 5242) and the ES (28273 ± 3102). Anther length (AL) and width (AW) were higher in the IS (5.3 and 0.8 mm, respectively) compared with the ES (6.4 and 0.6 mm, respectively); ES and the MS had intermediate values (5.2 and 0.7 mm, and 4.9 and 0.6 mm, respectively). No significant differences (p=0.18) were observed in PGF per sector in capitula of Havasupai (average= 42679 ± 4107). On the other hand, Hopi flowers of the MS and IS produced a larger number of pollen grains (average = 53412 ± 3553) than those of the ES (37050 ± 5947). PGV showed no significant differences in both hybrids, capitulum sectors and growing seasons (average = 22168 ± 1042 μm3). A positive relationship between AL and AW and the total number of pollen grains was also observed. Pollen viability in both growing seasons was greater than 97% in all cases. At harvest, in all cases, the higher number of FDF was observed in the ES and MS (598 and 456 respectively) and the number of IDF was higher in the IS (132). Given that intra-plant pollen production of both, pollen quantity and viability were not limiting, the origin of IDF in different regions of the capitulum could not be explained by the lack of pollen.The finding of an a typical positive centripetal gradient of pollen grains in the capitulum as compared with other racemose inflorescences is interpreted as an adaptive response to the time sequence of anthesis in this species to ensure a homogeneous pollination in the capitulum.

Airborne pollen content of Kuşadası

Atmospheric pollen grains of Kuşadası were captured using Durham samplers and investigated in 2005. The total number of pollen grains and the pollen grains/cm^2 were calculated from slides that were changed weekly. During the study period a total of 12,980 pollen grains/cm^2 belonging to 44 identified taxa and unidentified pollen grains were recorded at 2 stations. At the first station (S1), 7346 pollen grains were counted per cm^2, while only 5634 pollen grains were counted at the second station (S2). The majority of the investigated pollen grains were from Olea europaea L. (34.46%), Cupressaceae/Taxaceae (30.04%), Pinus spp. (19.71%), Platanus spp. (4.41%), Poaceae (3.70%), and Morus spp. (1.22%). In addition, 41.22% of the annual pollen index was captured in May. According to our results, seasonal pollen durations for the predominant pollen grains in Kuşadası were as follows: nearly the whole year for Cupressaceae/Taxaceae, Pinus spp., and Poaceae; March-September (between the 17th and 35th weeks) for Olea europaea; March-May (between the 11th and 21st weeks) for Platanus spp.; and March-April (between the 11th and 17th weeks) for Morus spp.