Highest Number Of Pollen Grains Research Articles

Reproductive Ecology of Distylous Shoreside Polygonum criopolitanum Hance

In this study, distyly was clearly confirmed in Polygonum criopolitanum Hance, which exhibited strict self-incompatibility. Unlike other distylous species, style-morph ratios of P. criopolitanum often deviated obviously from 1:1, and many populations were solely composed of long or short stylous flowers; the 1:1 style-morph ratio was occasionally found in very large populations. P. criopolitanum was dimorphic for intrinsic features such as style height and anther height and ancillary features such as pollen size and number. The L-morph flowers produced a significantly smaller and higher number of pollen grains than the S-morph flowers, and the stigma papillae of both morphs were not significantly different. We nearly found no seed sets in most wild populations and very low seed sets occasionally occurred in large populations, which was different from other species of Polygonaceae. Mating experiments showed that P. criopolitanum has a strict self-incompatibility system and clonal propagation was more common than sexual propagation, which was adaptive with the unisexual wild populations. Hygrocolous habitat, 20–60% soil water content, and height gap less than 4 m to the adjacent water were the main limiting factors for the distribution of P. criopolitanum.

Effects of sexual dimorphism on pollinator behaviour in a dioecious species

Floral traits often display sexual dimorphism in insect‐pollinated dioecious plant species, with male individuals typically being showier than females. While this strategy is theorized to be optimal when pollinators are abundant, it might represent a risk when they become scarce, because the disproportionately high number of visits on the most attractive sex, males, might preclude efficient pollen transfer from males to females. Here, the effect of sexual dimorphism on pollination efficiency was assessed in experimental arrays of dioecious Silene dioica that were exposed to one frequent visitor of the species, Bombus terrestris, and that differed in the magnitude of sexual dimorphism for either flower number or flower size. We found that flower number dimorphism negatively affected the number of visits on female plants, on female flowers and on the number of female flowers visited after a male flower. However, flower number dimorphism had no effect on the number of pollen grains deposited per stigma, presumably because the decrease in the number of visits to female flowers was compensated by a higher number of pollen grains deposited per visit. Flower size dimorphism did not affect visitation patterns and pollen transfer in our experimental arrays. These results highlight the need to jointly study visitation patterns and pollen receipt on stigmas when exploring the effect on floral phenotypes on pollination efficiency.

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).

Numerical methods and image processing techniques for melissopalynological honey analysis

Pollen analysis is a method used for verification of the botanical and geographical honey origin. Currently, much effort is being made to introduce automated systems with the use of image analysis programs. The automatic analysis is impeded by the insufficient depth of field of objects when using a light microscope, however, this can be avoided by using image reconstruction from images obtained from different focal planes. In this method, testing was performed on the normal focus (NF) and extended-depth-of-focus (EDF) images. These two methods were compared and statistically evaluated. The number of pollen grains and selected morphometric characteristics were compared. For EDF images, a higher number of pollen grains was obtained for the analysis, and except for the length/width ratio, a statistically significant difference was observed in the characteristics of pollen grains between the compared NF and EDF methods.

Pollen Grain Counting Using a Cell Counter.

The number of pollen grains is a critical part of the reproductive strategies in plants and varies greatly between and within species. In agriculture, pollen viability is important for crop breeding. It is a laborious work to count pollen tubes using a counting chamber under a microscope. Here, we present a method of counting the number of pollen grains using a cell counter. In this method, the counting step is shortened to 3min per flower, which, in our setting, is more than five times faster than the counting chamber method. This technique is applicable to species with a lower and higher number of pollen grains, as it can count particles in a wide range, from 0 to 20,000 particles, in one measurement. The cell counter also estimates the size of the particles together with the number. Because aborted pollen shows abnormal membrane characteristics and/or a distorted or smaller shape, a cell counter can quantify the number of normal and aborted pollen separately. We explain how to count the number of pollen grains and measure pollen size in Arabidopsis thaliana, Arabidopsis kamchatica, and wheat (Triticum aestivum).

Biological features of flowers influence the fertility of Lonicera spp. cultivars

Fertility experiments were carried out on a plantation of haskap berries (40 cultivars) in southern Poland. Based on the observation of phenological phases, the cultivars were divided into three groups with similar overlapping periods of full flowering: the earliest comprising 11 cultivars; the moderate-early, 17 cultivars; and the latest, 7 cultivars. The attractiveness of cultivars for pollinating insects was evaluated on the basis of flower biometric measurements. Flowers are more diverse in length than in width of the sympetalous corolla, with the pistil always being longer than the corolla, which is conducive to effective insect pollination. A pollen viability coloring test and germination capacity on agar medium were used to assess pollen quality. Despite very high pollen viability (on average, 90%), the percentage of germinating pollen was very low and ranged from 3.3 to 34.5%. Pollen yields for each cultivar were calculated based on the number of pollen grains in the flowers. The cultivars differed significantly in terms of the number of pollen grains in the flowers. The cultivar “Morena” was characterized by the highest number of pollen grains (45,375), while the cultivar “Fialka” had the lowest (2750). Microscopic observations of pollen tube overgrowth through the style of the pistil after open pollination and self-pollination allowed for calculation of the pollen germination index (PGI) used to assess the fertility of the cultivars. Self-pollinated cultivars with a PGI 2, which proves the self-fertility tendency of this cultivar.

The goosefoot in the air of selected Polish cities in 2018

This paper presents the course of goosefoot pollination in selected cities of Poland in 2018. The measurements were performed in Bialystok, Bydgoszcz, Cracow, Drawsko Pomorskie, Lublin, Olsztyn, Opole, Piotrkow Trybunalski, Sosnowiec, Szczecin, Warsaw, Wroclaw, and Zielona Gora. Volumetric method with the use of Volumetric Spore Trap (Burkard, Lanzoni) was implemented. In the studied cities in 2018, pollen season of goosefoot started in the third decade of May and ended in the third decade of September. Goosefoot pollen stayed in the air for more than 100 days – 142 days in Sosnowiec and 109 days in Bialystok. Maximum daily concentration (26 P/m3) was noticed in Bialystok, although the lowest – in Cracow (7 P/m3). In the majority of the measuring points the highest moment of pollen season was in August. The highest number of pollen grains in 2018 was found in Lublin (478 grains), the lowest – in Cracow (149 grains). The concentration above 10 P/m3 was very rare, only in Lublin it was this high for 12 days and in Warsaw for 8 days.

Evaluation of Pollen Quality and Self-Fertility in Selected Cultivars of Asian and European Pears

Asian pears have become increasingly popular in the European market, but their cultivation history in Europe is rather short. Pear is a demanding species in terms of pollen – donor cultivar. The self-fertility phenomenon in Asian pear cultivars is not currently known. The study was conducted in a 6-year pear orchard (of 23 Asian and 5 European cultivars) at the Mendel University in Lednice (Czech Republic). The following traits were assessed: number of pollen grains, pollen viability, pollen grain germination, self-fertility and the pollen germination index (PGI). European cultivar – ‘Clapp’s Favourite’ and Asian cultivars – ‘Zao Su Li’, and ‘Shinko’ were characterized by the highest number of pollen grains (over 50,000 grains). Asian cultivar ‘Dangshansu Li’ had the lowest number of pollen grains (less than 10,000 grains). The pollen viability of Asian pears ranged between 90 and 100%. Among European pears, ‘Williams Bon Chrétien’ and ‘Clapp’s Favourite’ exhibited the highest pollen viability (90%), while the lowest viability was observed for the pollen of cultivars ‘Beurré Bosc’ and ‘Alexander Lucas’ pear (60-70%). Additionally, it was found that the germination capacity of the latter two cultivars was very weak (40-70%). After open– pollination all investigated cultivars exhibited greater pollen germination index (PGI) comparing to self-pollination. After the cross-pollination the percentage of pollen tubes below the 20% value at half the length of the pistil suggested a strong incompatibility between the crossed cultivars. The results clearly showed that none of the Asian cultivars are self-fertile, and they require a pollen – donor to produce fruits.

Differential self-fertilization rates in response to variation in floral traits within inflorescences ofAquilegia buergerianavar.oxysepala(Ranunculaceae)

To assess variation in the proportion of self-fertilized seeds among flowers within inflorescences and the relationship between floral traits and the rate of self-fertilization, the proportion of self-fertilized seeds among individual flowers was estimated using ten microsatellite markers in self-compatible plants of Aquilegia buergeriana var. oxysepala. Within-inflorescence variation in floral traits, such as the duration of the male and female phases, flower size, herkogamy and the number of pollen grains and ovules in two natural populations, were investigated. The first flower in an inflorescence produced more seeds and a higher proportion of self-fertilized seeds than the second flower. The higher proportion of self-fertilized seeds in the first flowers was accompanied by a higher number of pollen grains and ovules in the bud stage and the female phase. These results indicate that the high proportion of self-fertilized seeds in the first flowers in an inflorescence may be due to the high number of remaining pollen grains in the female phase. This suggests that variation in floral traits within inflorescences affects seed quality and quantity among flowers within inflorescences.

Establishment of growth medium and quantification of pollen grains of olive cultivars in Brazil's subtropical areas

Pollen grain germination in vitro indicates viability and consequently provides information related to fruit set. It also assists in the development of hybrids. Along with a suitable species, a standard culture medium is essential for evaluating pollen viability. It should contain a gelling agent consisting of carbohydrates and enhancer elements as well as have the correct pH, temperature, and incubation time. The objective of this study was to optimise the culture medium, determine the pollen germination capacity, and quantify the number of pollen grains per flower of certain olive tree cultivars. A basic sequential culture medium for pollen grain germination was determined, always utilizing the best result from the previous experiment to continue the sequence.The factorial treatment arrangement was: 1) agar versus boric acid; 2) pH versus sucrose; 3) calcium nitrate versus magnesium sulfate. After determining the culture medium components, two experiments were conducted evaluating temperature and incubation time. Another experiment evaluated both the germination percentage and the number of flower pollen grains of 28 cultivars. The culture medium should be composed of 4 g∙L-1 of agar, 90 g∙L-1 of sucrose, and 400 mg∙L-1 of boric acid with a pH adjusted to 5.79 and an incubation time of 60 h at 28 °C. The Manzanilla 215 cultivar had the highest germination rate while Ascolano 315 presented the highest number of pollen grains per flower.

Aeropalynological survey in Büyükorhan, Bursa

An aeropalynological survey of the atmosphere of Buyukorhan in Bursa Province was carried out from January 2012 to December 2013 using a Durham gravimetric sampler. The number of pollen grains per cm2 was calculated on a weekly basis. Over 2 years a total of 13,274 pollen grains/cm2 from 44 taxa, including 24 arboreal plants (APs) and 20 nonarboreal plants (NAPs), and unidentified pollen grains were recorded. In 2012 and 2013, respectively, 5159 and 8115 pollen grains were recorded. The pollen grains consisted of 87.46% APs, 12.20% NAPs, and 0.35% unidentified plants. Pinus, Cupressaceae/Taxaceae, Quercus, Poaceae, Morus, Plantago, Olea europaea, and Cedrus were responsible for the highest pollen amounts in the study area. The highest number of pollen grains (49.84%) was recorded during May.

Role of pollen production in mating success in some tropical tree species

This study was conducted to estimate the amount of pollen produced by three entomophilous and two ornithophilous tropical woody taxa. It seeks to establish their reproductive success in relation to each other and contribution to the concentration of pollen in the air. The taxa selected were Bombax ceiba, Erythrina stricta (both ornithophilous), Lagerstroemia speciosa, Mesua ferrea and Schima wallichii (all entomophilous); which were studied in three different calendar years (2010, 2011 and 2012). M. ferrea produced the highest number of pollen grains per tree (3.85–6.60 × 1010) and B. ceiba highest number of pollen grains per anther (18,610 ± 1,189.49). The pollen grains produced were estimated to be about 100 million per tree in all the studied species except M. ferrea, which produced about 10 billion pollen grains per tree. There were both good and poor production years in all the studied species. During the course of the 3-year study, B. ceiba, E. stricta and S. wallichii produced maximum number of pollen grains per tree in the year 2011, whereas maximum pollen production was observed in M. ferrea in the year 2010. However, the 2 years (2010 and 2012) mass production was observed in L. speciosa. During the high pollen production years, the fruit setting was also recorded to be high. It is interesting to point out that in E. stricta, the fruit setting was 88.5 and 91.72 % higher (i.e. 39.12 ± 3.63 %) in the year 2011 as compared to the years 2010 (4.48 ± 0.63 %) and 2012 (3.24 ± 0.49 %), respectively.

The effects of landscape on bumblebees to ensure crop pollination in the highland agricultural ecosystems in China

AbstractHoney bees and wild bees provide critical pollination services to agricultural ecosystems; however, the relative contributions of different bee taxa are not well understood. The natural habitats surrounding farmland support food and nesting resources for wild bees and therefore play an important role in the maintenance of crop pollination. In this study, we selected Cucurbita pepo L. (squash) as a model crop to investigate the relative importance of honey bees and bumblebees in pollinating the crop. Thirteen fields, which were surrounded by a gradient of natural habitat, were investigated on the Yunnan‐Guizhou Plateau in China. We measured the visit densities of honey bees and bumblebees, the number of pollen grains deposited in a single visit by the two bee taxa, as well as the overall pollen grains deposited on stigmas during a flowering day, and then used Bayesian inference to decouple the pollen grains deposited by either the honey bees or the bumblebees. Compared with honey bees, bumblebees deposited a higher number of pollen grains on stigmas in a single visit, but had a lower visit density than honey bees. Meanwhile, the bumblebee visit density increased along the proportion of natural habitat, while the honey bee visit density was not affected by the surrounding natural habitat. Data simulations using Bayesian inference showed that on a flowering day, the number of pollen grains deposited by bumblebees increased with the proportion of natural habitat in the surrounding landscape, but the number of pollen grains deposited by honey bees did not. Moreover, the total numbers of pollen grains deposited by honey bees or bumblebees alone were all below 2000 (the critical level to satisfy the pollination requirement of this crop). Pollen calculations demonstrated that the number of pollen grains deposited by the two bee taxa was greater than 2000 in fields surrounded by more than 13% natural habitat (grasslands and forests). The results revealed that bumblebees ensured C. pepo pollination in combination with honey bees in the highland agricultural ecosystems.

Tree Pollen Spectra and Pollen Allergy Risk in the Osijek-Baranja County

The forests of north-eastern Croatia, as well as various plants and trees in the parks and streets of the Osijek-Baranja County, produce large amounts of pollen during the pollen season, which can cause allergy symptoms in pollen sensitive individuals. The aim of this study was to determine the most frequent types of pollen in this area and estimate possible health risks, especially the risk of allergy. In 2009 and 2010, the staff of the Health Ecology Department of the Osijek Public Health Institute monitored tree pollen concentrations in four cities from the Osijek - Baranja County (Osijek, Našice, Đakovo and Beli Manastir) using a Burkard volumetric instrument. The results were affected by weather conditions. Windy and sunny days facilitated the transfer of pollen, whereas during rainy days, the concentration of pollen grains decreased. High pollen concentrations of Cupressaceae/Taxaceae, Betulaceae, Salicaceae and Aceraceae could be the cause for symptoms of pollen allergy. In 2009, conifers, birch and poplar pollen were dominant at all monitoring stations with 5000 pollen grains (PG), 3188 PG and 3113 PG respectively. The highest number of pollen grains was recorded at measuring site Osijek. The variations in airborne pollen concentration between pollen seasons were recorded at all monitoring stations. The most obvious variations were recorded at measuring site Osijek. The usual pollination period lasts two to three months, which means that most pollen grains remain present from February to early June. However, the Cupressaceae / Taxaceae pollination periods last the longest and their pollen grains remain present until the end of summer. The risk of allergy was determined at four monitored measuring stations and the obtained data confirmed that the largest number of days with a high health risk was at the Đakovo measuring station for a species of birch. The research information aims to help allergologists and individuals allergic to plant pollen develop preventive measures and proper treatment therapies.

Floral Biology and Pollination Ecology of Cowpea (Vigna Unguiculata L. Walp)

Studies on the floral biology and pollination ecology of three varieties of cowpea (Vigna unguiculata L. Walp) were carried out. The varieties studied were Var. Oloyin, Var. Sokoto, and Var. Drum. Cowpea is a self pollinated crop which is encouraged by the arrangements of the floral parts. However, Insects visiting cowpea flowers have been implicated in the movement of pollen from one cowpea plant to another. Flower opening of cowpea begins between 6:00am and 6:30am and closes between 11:30am and 12:00pm. Pollen analysis showed similarities in the pollen morphology of the cowpea varieties. Moreover Var. Drum produced the highest number of pollen grains per flower in terms of pollen productivity.

Effects of environmental factors on pollen production in anemophilous woody species

The aim of this study was to estimate the amount of pollen produced by anemophilous woody taxa with allergenic properties and with considerable contribution in the concentration of pollen in the air of a Mediterranean city (Thessaloniki, Greece). The taxa selected are Corylus avellana, Cupressus sempervirens var. horizontalis and var. pyramidalis, Olea europaea and Platanus orientalis; each was studied in more than one sampling stations differing in elevation, direction or both. O. europaea produced the highest number of pollen grains per flower (1.3 × 105 ± 0.1 × 105) and P. orientalis the highest per inflorescence (3.3 × 106 ± 0.2 × 106). At the level of crown, pollen grains produced were of the order of 109 per surface/volume unit for O. europaea and the two C. sempervirens varieties; for the other two taxa, they were of the order of 106. Pollen production was lower at higher elevation and northern direction and depended on the size of the floral unit sampled (flower for O. europaea, inflorescence for all other species): the bigger the floral unit, the more pollen it contained. Our results and reports from other areas, where C. sempervirens and O. europaea grow, show that these two Mediterranean species produce comparable amounts of pollen at the levels of inflorescence or flower, respectively, wherever they occur.

Pistil traits and flower fate in apricot (Prunus armeniaca)

AbstractAlthough pollination is essential for both seed and fruit set in most angiosperms, even after an adequate pollination, only a fraction of the flowers develop into fruits. The role played by floral traits on reproductive success is well known, but the possible influence of pistil traits has been overlooked, probably because of the difficulty of non‐destructive pistil examination. The aim of this work was to examine the influence of several pistil traits on reproductive success in apricot (Prunus armeniaca). For this purpose, in a population of individually labelled flowers, the styles were cut off once the pollen tubes had reached the ovary but prior to the achievement of fertilisation. This approach allowed relating several morphological and physiological pistil parameters in the dissected styles and stigmas to the subsequent set or abscission of the corresponding ovary that remained in the plant. Under the same pollination conditions, the flowers that finally set a fruit show a larger stigmatic area and a higher number of pollen grains, pollen tubes growing along the style and xylem vessels surrounding the transmitting tissue than flowers that abscise before the establishment of fruit set. Furthermore, starch is present in the transmitting tissue of the style in all the flowers that develop into fruits but only in half of the flowers that abscise. The examined pistil traits established prior to fertilisation are related to flower fate, suggesting that the capacity of a flower to become a fruit could be preconditioned at anthesis.

Nectar robbing of a carpenter bee and its effects on the reproductive fitness of Glechoma longituba (Lamiaceae)

The floral biology and pollination process of Glechoma longituba (Nakai) Kuprian, a clonal gynodioecious, perennial herb that is widely distributed in China was investigated in natural populations. During visits to the flowers of G. longituba, the carpenter bee—Xylocopa sinensis mainly displayed nectar-robbing behavior with minimal pollination. Nectar robbing behavior began at the onset of flowering and continued for about 3 weeks ending at about the middle of the flowering period. A total of 18.6% floral visits in this period were by nectar robbers, with about 90% of the flowers in the study populations being subjected to two or two nectar-robbing episodes. During controlled experiments, lower pollination efficiency was recorded for X. sinensis compared to legitimate pollinators. Pollination by the robber-like pollinator X. sinensis during the early-mid phase of the flowering season yielded seeds of 16.16%. Although nectar robbing by the carpenter bee seemed to have a slight enhancing effect on seed set in G. longituba, this effect was effectively masked by the more pronounced detrimental effect of nectar robbing. Experiments indicated that nectar robbing by the carpenter bee reduced seed production by more than 26%, largely owing to the consequent shortening of the life span of robbed flowers. Furthermore, 10.43% of the ovules and 13.04% of the nectaries in the robbed flowers were damaged, thus causing a decrease or entire loss of reproductive opportunity in the robbed flowers. In addition, a higher number of pollen grains remained on the androecia of robbed flowers indicating that nectar robbing may have a lowering effect on male fitness in G. longituba.

Quality fruit improvement in sweet pepper culture by bumblebee pollination

Abstract The percentage of ovules that set seeds per fruit has been used to evaluate the bumblebee activity of a two campaigns greenhouse trial. The experiment was carried out with two commercial cultivars of sweet pepper, ‘bell’ type, called Bardenas and Vergasa. The averages of the percentages of seed set per fruit of the two campaigns were 49.8% (Bardenas) and 40.7% (Vergasa) on the pollination treatment, whereas the averages of the control (self-pollination) treatment were 27.5% and 25.7%, respectively. Percentages of seed set per fruit was strongly related with the number of bee visits, but weakly with duration of visits. The number of pollen grains deposited on stigmas by pollinators or by self-pollination was assessed by staining and microscopy, resulting in a higher number of pollen grains on the bumblebees-pollinated flowers than on the control (self-pollination) ones. As a consequence of this, the number of seeds set on the bumblebees-pollinated fruits, was always higher than in the control. Flowers visited by bumblebees produced larger and heavier fruits than non-visited flowers. Because fruit external maximum diameter, length and weight were highly dependent on seed set, the use of pollinators seems to be required to obtain sweet pepper fruits with improved quality characteristics. Percentage of seed set per fruit was correlated with the number of bumblebee visits to the flowers, seeds per fruit, number of pollen grains on stigma, and the quality fruit traits. The number of pollen grains per stigma was correlated with the number of seeds per fruit.

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.