Pollen Density Research Articles

Reevaluation of pollen differentiation in Altingiaceae: Challenges in distinguishing deciduous (Liquidambar) and evergreen (Altingia) types using multivariate statistics and machine learning

Altingiaceae, a family of woody plants, comprising evergreen Altingia and deciduous Liquidambar groups, exhibits distinct leaf morphology, yet both groups overlap in geographical range and climatic conditions. While some tropical Altingia species are confined to Myanmar, Thailand, Cambodia and India without Liquidambar, and some temperate Liquidambar species to northern China without Altingia. Their fossil pollen have significant implications in reconstructing palaeoclimate and historical biogeography, based on classification of Altingia-type and Liquidambar-type. However, the results of previous studies to differentiate pollen types of evergreen Altingia and deciduous Liquidambar were based on limited pollen specimens. Therefore pollen morphology of Altingiaceae and differentiation of above mentioned types needs reevaluation using more specimens from wider geographical range.In this study, we present new findings on Altingiaceae pollen morphology from extensive collection of specimens and reassess the diagnostic features to distinguish evergreen and deciduous types. To improve the credibility of palaeoecological and palaeoclimatic interpretations, we applied multivariate statistical analyses to pollen size, number of pores, pollen wall thickness, and size and density of ornamental elements from light microscopy (LM) and Scanning Electronic Microscope (SEM) images. Additionally, random forest classification models were applied to test the accuracy of differentiating Altingiaceae pollen types. Our results reveal significant morphological overlap between the pollen of evergreen Altingia and deciduous Liquidambar, with classification models showing limited accuracy and explainability. Thus, fossil pollen of Altingiaceae cannot be confidently classified into evergreen or deciduous types, highlighting challenges in using their pollen morphology for taxonomic classification in palaeoecological research.

Characterization of biotic and abiotic signatures of modern lake sediments of western India, and its palaeo-environmental implications

A multi-proxy study of biotic and abiotic components was conducted on surface sediment samples from six lakes/wetlands located along the western transitional boundary of the contemporary Indian Summer Monsoon (ISM) in the Indian Subcontinent. The primary goal is to assess the suitability of various proxies as representatives of modern vegetation, environmental and climatic conditions. The collected data indicate significant variations in the composition and density of pollen in response to climate-induced and anthropogenic ecological changes throughout the northwest India transect. The palynological studies from eastern Rajasthan shows high forest elements in comparison to western Haryana and western Uttar Pradesh. In addition, the palynological data was juxtaposed with other biotic proxies such as diatom and isotopic studies, along with geochemical proxies and paleomagnetic data of the surface lake sediments. The presence of marker pollen taxa including Cerealia type Poaceae, Chenopodiaceae, and Brassicaceae, allows for distinct recognition of anthropogenic activities throughout the whole transect. The diversity and distribution of diatoms also support the palynological data in response to climate-induced and anthropogenic ecological changes. Furthermore, grain size, geochemistry (TOC/TN ratio with stable carbon isotope), and magnetic susceptibility data offer crucial insights about the sediment's depositional settings and general mineralogical composition. Stable carbon isotope data shows C3 dominance in relatively humid areas and C4 dominance in semi-arid areas, suggesting climate-driven control over sediment organic matter composition. Canonical correspondence analysis (CCA) indicates that biotic variables (pollen, diatom, stable isotopic composition) are significantly controlled by modern precipitation and temperature. Redundancy analysis reveals a significant influence of current average temperature and precipitation on major element oxide variations in surface lake sediments. Therefore, we propose using palynological, stable carbon isotope, diatom data, along with grain size, environmental magnetism, and geochemistry, to establish a multiproxy modern analogue for quantitative palaeoclimatic reconstructions. As a result, this study provides the first modern analogues from a climate-sensitive region that separates the area under ISM influence from an area with meager precipitation in western India.

Studies on pollen performance in some endangered medicinal and aromatic plants of cold desert Ladakh

The study was carried out at the Trans-Himalayan Herbal Garden, located at the National Institute of Sowa Rigpa-Leh, from 2021 to 2023. An assessment of pollen viability was conducted using seven significant medicinal and aromatic plants from the Ladakh region. Analysis of pollen vitality was conducted using the acetocarmine staining technique. The pollen viability of Inula racemosa Hook. f. ranged from 91.08 ± 1.39 % to 82.44 ± 1.48 % in Ephedra gerardiana Wall. Among the genus Inula racemosa, the highest percentage (91.08%) of viable pollens indicates a normal meiosis, whereas Ephedra gerardiana recorded the lowest percentage. Among the chosen species, Inula racemosa, Verbascumthapsus, Hyoscyamus niger, and Dracocephalum heterophyllum stand out for their exceptional pollen viability. These species can be effectively utilized for conservation purposes and as male parents in hybridization. The result for the average pollen density varied from 1533.07 ± 106.32 in Capparis spinosa L. to 276.00 ± 10.20 in Dracocephalum heterophyllum.

Plant Growth Regulators Enhance Maize (Zea mays L.) Yield under High Density by Optimizing Canopy Structure and Delaying Leaf Senescence

Shaping the canopy architecture and delaying leaf senescence in maize are pivotal strategies for extending the crop’s photosynthetic period and improving yield. The application of plant growth regulators (PGRs) is a critical cultivation measure, with the timing of application being of paramount importance. To explore the effects of PGR application time on maize canopy structure, leaf senescence characteristics and yield, a comparative two-year field study was undertaken during the 2019–2020 growing seasons at the Gongzhuling Experimental Station of the Jilin Academy of Agricultural Sciences, utilizing a PGR containing ethephon as the active ingredient. The experiment was structured with two plant densities of 60,000 and 90,000 plants ha−1, and three distinct PGR application protocols: T10 (application of PGR at the 10th leaf stage), T15 (application at the 15th leaf stage), and CK (control group sprayed with water). The result indicated that the yield increased by 5.62% following T15 treatment compared to the CK under high density (90,000 plants ha−1). Furthermore, the kernel per ear and the 1000-kernel weight increased by 3.93% and 5.62% respectively, while the abortion rate decreased. Correlation analysis showed that yield and yield components were correlated with plant morphology, physiology, and aging characteristics under 90,000 plants ha−1. Pollen density was also positively correlated with the top leaf area and the top leaf angle (p < 0.01). Furthermore, relative green leaf area at maturity (RGLAM) showed positive correlations with chlorophyll b, superoxide dismutase activity (SOD), peroxidase activity (POD), catalase activity (CAT), and soluble protein content (p < 0.01), while displaying a negative correlation with malondialdehyde content (MDA) (p < 0.01). Spraying plant growth regulators at the 15-leaf stage under high density can effectively enhance the top canopy structure of the maize and reduce the upper leaf area and angle, increase pollen density, and boost the number of grains. Furthermore, it delayed the senescence of leaves, prolonged the functional period of the leaves, increased kernel weight, optimized light resource utilization, and ultimately enhanced the maize yield.

Classification of buckwheat honey produced in Kazakhstan according to their biochemical ingredients and bioactivities by chemometric approach

Herein, nineteen buckwheat honey samples collected from 19 stations of different ecological zones of Kazakhstan were analysed for their pollen density, physicochemical properties, chemical composition, antioxidant, anticholinesterase, tyrosinase inhibitory, and urease inhibitory activities with chemometric approaches. Twelve phenolic compounds and fumaric acid were identified using HPLC-DAD, and mainly fumaric, p-hydroxybenzoic, p-coumaric, trans-2-hydroxy cinnamic acids, and chrysin were detected in all samples. The honey samples collected from the Northern zone exhibited best antioxidant activity in lipid peroxidation inhibitory (IC50:8.65 ± 0.50 mg/mL), DPPH• (IC50:17.07 ± 1.49 mg/mL), ABTS•+ (IC50:8.90 ± 0.65 mg/mL), CUPRAC (A0.50:7.51 ± 0.30 mg/mL) and metal chelating assay (IC50:10.39 ± 0.71 mg/mL). In contrast, South-eastern zone samples indicated better acetylcholinesterase (55.57 ± 0.83%), butyrylcholinesterase (49.59 ± 1.09%), tyrosinase (44.40 ± 1.21%), and moderate urease (24.57 ± 0.33%) inhibitory activities at 20 mg/mL. The chemometric classification of nineteen buckwheat honey was performed using PCA and HCA techniques. Both were supported by correlation analysis. Thirteen compounds contributed significantly to the clustering of buckwheat honey based on geographical origin.

Debunking wasp pollination: Wasps are comparable to bees in terms of plant interactions, body pollen and single‐visit pollen deposition

Abstract Wasps are understudied in their contribution to pollination services. In order to better understand the ecological contribution of wasp communities to plant pollination, we conducted three studies to compare bees and wasps by (1) the plant communities visited in agricultural and prairie environments, (2) body pollen composition as an indirect measure of pollination and (3) a single‐visit deposition study as a direct measure of pollination in the plant species complex Solidago canadensis. We found wasps visit a distinct early‐blooming exotic plant community from bees but have overlapping use of late‐blooming native plants and similar network interaction metrics. This suggests wasps may fill an ecological niche distinct from bees, while also serving as common native plant visitors. We also found that body pollen density and pollen fidelity in four and five (out of six) wasp families, respectively, were comparable to or greater than the bee family Colletidae. Three wasp families also showed comparable to or greater visit fidelity than two (out of five) bee families examined. These results suggest wasps may carry and potentially deliver substantial pollen to specific plants. In addition, controlled single‐visit deposition revealed the paper wasp Polistes fuscatus deposits a similar amount of pollen grains as the bumble bee Bombus impatiens, suggesting surprisingly high pollination efficiency that warrants further investigation. Our multi‐pronged study shows the importance of investigating the role of wasps as pollinators, especially by focusing on direct plant‐pollination metrics to determine wasp pollination efficacy.

Effects of Frankliniella occidentalis (Pergande) density and loofah pollen on development and fecundity of Orius similis Zheng

AbstractOrius similis Zheng, a predatory bug that feeds on Frankliniella occidentalis (Pergande), a pest that damages vegetables and ornamental plants by feeding and transforming plant viruses. O. similis is an omnivorous predator on thrips, as well as pollen. Our study investigated the impact of five different amount densities of thrips and abundant loofah pollen on the survival, development, fecundity, and consumption of O. similis. The performance of O. similis nymphs and adults was significantly affected by the density of thrips and loofah pollen on which they fed. The highest survival and shortest development period of O. similis nymphs after feeding on 40 thrips/d, while the lowest survival rate and longest period were observed after feeding on only 5 thrips. Feeding on loofah pollen alone also significantly increased survival and decreased the nymph development period compared with feeding on 20 thrips/d. The highest prey consumption occurred at densities of 30 and 40 thrips/d, while the lowest prey consumption occurred at a thrips density of 5, regardless of whether the O. similis were nymphs or female adults. However, adding loofah pollen decreased prey consumption of nymphs and adult females. In addition, O. similis showed higher fecundity and longevity when feeding on 40 thrips/d compared to other thrips densities and adding loofah pollen. Adding loofah pollen also increased fecundity and longevity compared to feeding on thrips alone at the same density, regardless of the thrips' density. Therefore, a high thrips abundant density daily was beneficial for the development, fecundity, and longevity of O. similis, and adding loofah pollen can enhance their performance.

Investigation of Some Quality Criteria in Chestnut Honey of Düzce Province

Honey is a natural food source that has been consumed by humans for thousands of years and has an important place in various cultures. Chestnut honey is an important type of honey produced in Düzce province. Determining the quality and purity of honey ensures that consumers have access to safe, high-quality honey. The control criteria for the suitability of honey for human health consumption are defined in the Turkish Food Codex Communiqué on Honey (2020/7). Düzce University Scientific and Technological Research Application and Research Center (DÜBİT) responds to requests for honey analysis for non-commercial, internal quality control purposes. In this study, the results of honey samples produced in the province of Düzce and analyzed in the laboratories of DÜBİT were examined according to the criteria of the Turkish Food Codex Communiqué on Honey and an evaluation of the results was carried out. According to the test results, 38%, 20% and 16% of the samples were found to be unsuitable for the quality criteria, especially for the sugar profile, conductivity and proline parameters, respectively. Additionally, pollen analysis of 13% of the honey samples revealed pollen densities that did not match the declared plant family. From a public health point of view, it is important to consume high-quality, reliable and natural honey products. Therefore, quality control of bee products should be carried out from the producer to the consumer.

Calibration and measurement of micrometre-scale pollen particles for discrete element method parameters based on the Johnson-Kendal-Roberts model

Discrete element method (DEM) parameters are the basis for modelling the motion of particle systems. To verify the practicality of calibrating DEM simulation parameters for micrometre-sized pollen particles, spherical micrometre-sized tomato pollen was selected as the research object for a parameter calibration experiment. Constitutive parameters such as the pollen morphology, diameter, and density were obtained through experimental measurements. Then, the contact and collision process of pollen was measured and analysed using an atomic force microscope, and Young's modulus, surface energy, and recovery coefficient of pollen were calculated using the Johnson-Kendal-Roberts (JKR) contact model. A Plackett-Burman test was designed, and the significant factors were determined using the DEM simulation test for Young's modulus of pollen grains, pollen-pollen static friction coefficient, and the pollen-polypropylene static friction coefficient for the plastic floor. The parameter range was reduced using the steepest climbing test. A regression equation was determined according to the results of the Box-Behnken response surface analysis. When this equation was solved, Young's modulus of pollen grains was 5.25 × 106 Pa, the pollen-pollen static friction coefficient was 0.466, and the pollen-polypropylene plastic static friction coefficient was 0.417. From the accumulation verification experiment the relative error between measurement and the simulation was 1.01%, which indicates that a calibration experiment of micrometre-sized pollen particle parameters is feasible. Furthermore, the parameters obtained here can be used to calculate and predict the pollen pollination process.

The The effect of feeding on rapeseed and bee bread plants on the biological activity and productivity of honey bee colonies Apis mellifera

The field study was conducted during the agricultural season 2022-2023 in three locations. The first is the apiary of the College of Agriculture and Forestry, in which the bee sects were feeding and resting on the natural wild plants and bushes present in the apiary and the surrounding areas. The second location was in one of the agricultural fields in the Rashidieh area, in which it was planted. Seeds of the bee bread plant Borago officinalis at a rate of one dunam. The third site was in one of the agricultural fields of the Al-Mazra'i neighborhood of Nineveh Governorate, in which rapeseed Brassica napus was planted, at a rate of one dunam as well. The results of the study showed that the treatment of bee bread (the second site) on 1/10 was superior in recording the highest bee density, worker brood, pollen grain area and mature honey area, which was positively reflected in the amount of honey produced, with averages of 17.66 bees, 785.66 inches2, 302.17 inches2, and 803 inches. 33 inches2 and 9.08 kg / colony, respectively, and the treatment of rapeseed plants (the third site) recorded satisfactory and good results in which it outperformed the comparison treatment with averages of 14.42 bees, 596.66 inches2, 257.66 inches2, 760.33 inches2, and 7. 63 kg / colony, respectively, while this percentage decreased in the comparison treatment (first site) on 11/11, which recorded the lowest averages of 5.17 bees, 341.33 inches2, 40.66 inches2, 118.33 inches2, and 2.54 kg. Respectively, the results confirmed the necessity of cultivating bee bread and rapeseed plants to provide beds and a good pasture of nectar and pollen through which bee colonies can cross the winter stage and obtain high bee density and good storage of honey and pollen.

The key determinant for forming pollen density and using crop barriers to mitigate wind-blown pollen dispersal in alfalfa (Medicago sativa L.)

The potential for commercial cultivation of genetically engineered (GE) alfalfa has raised ecological concerns due to the possibility of introgression of GE alleles into conventional populations. The main objectives of this study were to determine the key affecting factors (i.e. size of pollen source, number of pollinating bees) on forming alfalfa pollen cloud density and test the mitigating effect using maize barrier rows on alfalfa pollen dispersal. The results showed that the mean pollen densities of alfalfa pollen source (Ø = 10 or 20 m) were statistically similar when treated with the same number of worker bumblebees and increased accordingly with increasing the worker bees (887 and 853 pollens m−3 h−1 for Ø = 10 and 20 m with 100–150 worker bees, respectively; 1040 and 1070 pollens m−3 h−1 for the two plots with 200–300 worker bees, respectively), demonstrating that the number of worker bees but not the size of the pollen source was the key determinant for forming alfalfa pollen density. A maize barrier row established at 0.5 m from the alfalfa edge consistently decreased downwind pollen densities (percent pollen density of pollen source) to 0.2–4.4 % at 1–9 m compared to 3.4–25.4 % and 7.5–37.8 % at the same distance range for the upwind and downwind sites without maize barrier rows, respectively. Based on the pods formed on the emasculated alfalfa flowers (due to pollen dispersal) located at various distances from the pollen source and subsequent prediction model, the pollen density threshold value for fertilizing alfalfa recipient under the wind-blown condition was determined of 65.8 pollens m−3 h−1 at 14.7 m from the pollen source edge. The results would help in understanding the pollination biology (minimum pollen density for fertilizing alfalfa recipient ovule) and the process of pollen-mediated gene flow and helpful in developing management strategies to reduce the pollen density and thus mitigate the gene flow in alfalfa.

Development of inter-specific hybrids between Solanum melongena L. and Solanum sisymbriifolium Lam. through embryo rescue

In present investigation, inter-specific hybridization between two species was carried out using a three-way cross with the aim to study the response of heterotic hybrids for cross-compatibility and to improve the fertility traits of interspecific cross such as pollen viability and density for further introgression of agronomically important traits. The present investigation highlights genotypic variation of for cross-compatibility between S. melongena hybrids and Solanum sisymbriifolium. Among three hybrids, H3 x Solanum sisymbriifolium (4%) and H4 x Solanum sisymbriifolium (1.5%) showed compatibility for fruit set and developed immature seeds only. The embryo rescue from 25 day-old fruits and in vitro culture on ½ MS medium supplemented with 2mg/L–1BAP showed germination. H5 x S. sisymbriifolium showed 49.4% embryo germination and produced four complete plantlets. Furthermore, all plants were morphologically variable for the presence or absence of spines, flower clustering, slightly curved/straight stigma tip, and flower color. The regenerated plantlets were intermediate to cultivated and wild parents for the quantitative traits. Two SSR markers viz., emg01A17, emh11001 and emb01E03 also confirmed the hybridity of three-way cross plants. Among four interspecific plants, one established high pollen viability (78.5%), while others were partial-fertile (62.8%) and all carried low pollen density (69-299 pollen/ 1cm2) at anthesis. Inbreeding and backcrossing of these plants to both cultivated and wild parents remained unsuccessful. This is the first report of developing a partially-fertile three-way cross between S. melongena and S. sisymbrifollium via embryo rescue.

Morphological diversity of pollen grains within the flowering stages of Tecoma stans (L.) Juss. ex Kunth

The study of the morphology of pollen grains is essential to understand plant evolution, adaptation, diversity and discrimination of taxa. This study aims to determine the importance of choosing the perfect stage of flower development in the study of pollen morphological characters as a taxonomical tool. In this work a woody, perennial street tree Tecoma stans was chosen as a model species belonging to family Bignoniaceae. Tecoma stans has many polymorphic forms native to North America and flourished in hot climates. This tree is commonly planted in both Cairo and Alexandria streets. Samples of flower buds in nine different stages were gathered from five to six different trees from March to June 2023. Non-acetolysed pollen grains were investigated using both light and Scanning electron microscopes. The results showed that pollen density, size, shape beside colpi length as well as their state varied between the different developmental flowering stages and cannot be relied on taxonomical decisions, while exine ornamentation slightly differed between the pollen grains from stage two to nine, but it was faint in immature flower bud (stage one). This study confirms that we must be precise in choosing the correct flower stage in pollen morphological studies to obtain significant morphological description. The results obtained revealed that the aperture type is more stable than pollen shape and size.

Honey, its Quality and Composition and their Responsible Factors

Honey is a sweet viscous food substance made by honey bees. It contains more than 180 nutritional substances, due to which it is known for boosting immunity. Honey is comprised of easily digestible honey sugars and energy providing nutrients. It is used as an ingredient in hundreds of manufactured foods for its sweetness, colour, flavor, caramelization and viscosity. It’s various physicochemical constituents, moisture content (<25%), reducing sugars (>65%), acidity (<0.2%), electrical conductivity (<0.8 mS/cm for blossom honey), sucrose content (5%), hydroxy methyl furfuraldehyde (HMF) (<40 mg kg-1) etc. contribute to its nutritional quality, granulation, flavor, texture, fermentation and storage quality. Other properties viz. diastase content, proline content, phenols, pollen density etc. are important indicator of quality and origin of honey. Honey is the reservoir of different minerals, with potassium being most abundant element. Owing to its chemical composition, honey has been reported to have significant impact on human nutrition and health. Its quality is evaluated based on standard quality parameters standardized by different authorities. The quality and composition of honey highly depends on the type of flowers utilized by the bees, climatic conditions and various other factors like floral sources, seasons, beekeeper activities, harvesting of honey, processing, storage, agrochemicals, adulteration and geographical origin. The demand of honey is also increasing in upward trend; thus, the analysis of these quality parameters helps us to ensure that the honey we are consuming fulfills the required parameters.

Physico-Chemical Characteristics and Correlation Analysis of Honey of Wild Honeybees

Honey of wild honey bees Apis dorsata and Apis florea was sampled from northern states of India during the year 2018-20 and analyzed for physico-chemical parameters and microbial load using standard procedures and correlation analysis. A. dorsata honey had high moisture content (17.20%), pH (6.25) and F: G ratio (1.98), whereas A. florea honey exhibited higher bacterial loads (3.82) than A. dorsata (3.70). No fungal spores were recorded in any of the honeys analyzed. Significant positive correlation was recorded between colour and pollen density; amino acid content and acidity; Vitamin C and acidity in honey of A. dorsata. Whereas Electrical Conductivity (EC) and pH; amino acid and acidity content in honey of A. florea had significant positive correlation. Bacterial load had significant positive correlation with pH and moisture. The quality parameters were well within the acceptable limit defined by the Food Safety Standards Authority of India.

Quantitative study of Artemisia pollens deposition in the upper airways of children with adenoidal hypertrophy

Studies regarding the pollen transport and deposition in children nasal airways are still scarce, especially the regional deposition doses, which is difficult to provide guidance for precise application of pollen blockers and nasal administration. In addition, most previous investigations included only one child case, which lacked statistical significance. To this end, we used computational fluid particle dynamics (CFPD) modeling approach to calculate the deposition pattern of Artemisia pollen at various anatomical sites in the upper airway of 12 children with adenoid hypertrophy (AH), and analyzed the effects of respiratory flow rate and pollen density on the deposition distribution. Adult nasal airways from our previous study were included for data comparison. We found that nasal cavities of children with AH aged 4–6 years had a greater area/volume ratio than adults did, and the area and volume of the turbinate region were less than half that of adults. The physical diameter of Artemisia pollen was set to 21.0 μm, with a shape of ellipsoid. Its average density is 1080 kg/m3 in the humid state and 550 kg/m3 in the dry state. In resting state, children with AH had higher deposition rates of wet Artemisia pollen in the nasal septum and nasopharynx, and lower deposition rates in the nasal vestibule and middle turbinate compared with adults. Under exercising conditions, wet pollen was deposited mainly in the nasal vestibule and the anterior part of the nasal septum in children. Compared to wet pollen, the deposition rate of dry Artemisia pollen in resting state was approximately halved and the pollen entering the lower respiratory tract rose approximately 47-fold. The findings suggest that nasal cavities of children are not simply scaled-down version of adults. Notable differences in deposition hotspots and deposition patterns have been discovered between the two. The deposition hotspots shifted significantly forward as the respiratory flow rate increased. Dry Artemisia pollen has a low density and is more likely to enter the lower respiratory airways, which may put children at a higher risk of developing asthma.

Optimizing the Working Parameters of Pneumatic Pollinators Based on the Kinematic Properties of Rice Panicles

Highlights An experimental platform for the kinematic characteristics of panicles was constructed. A regression model for the kinematic characteristics of panicles and working parameters was established. The multi-objective optimization based on the kinematic characteristics of rice panicles was carried out. The optimized combination of working parameters was verified by field pollination experiments. Abstract. Pollen shedding and dispersal processes are inextricably linked to the movement state of hybrid rice panicles. The purpose of this work was to study the effect of the working parameters of the pneumatic pollinator on the kinematic characteristics of hybrid rice panicles during flowering and to further optimize the working parameters of the pollinator. An experimental platform was built to characterize the movement of the panicle. Orthogonal experiments were conducted with airflow velocity, action position, and walking speed as experimental factors and kinematic parameters such as displacement, velocity, and acceleration of the rice panicle as experimental indicators. A quadratic regression model between the working parameters and the motion characteristics of the rice panicle was constructed and analyzed by analysis of variance (ANOVA). Matrix analysis was used for multi-objective optimization of the working parameter combinations. Field pollination trials were conducted for the optimized combination of parameters. The results showed that the coefficients of determination of the regression models were all above 0.85, which indicated good accuracy. The motion characteristics of the panicle, including the displacement maximum, velocity maximum, and acceleration maximum, can be maintained at a high level when the airflow velocity is 24 m/s, the action position is 120 mm from the top of the panicle, and the walking speed is 0.4 m/s. The field experiments showed that the optimization results could obtain the desired pollen density, distribution, and uniformity. This study can serve as a reference for the development of pneumatic hybrid rice pollination theory and the optimal design of the pollinator structure. Keywords: Hybrid rice seed production, Kinematic characteristics, Mechanized pollination, Multi-objective optimization.

Pollen analysis of honey from Laghouat region (Algeria)

A microscopic analysis of 41 samples of honey obtained from several locations in the Laghouat region revealed the presence of 98 pollen types belonging to 48 families. Asteraceae, Fabaceae and Nitrariaceae were present in all the samples. Brassicaceae, Rhamnaceae and Apiaceae were identified in more than 80% of the samples. The families with highest diversity of pollen types were Fabaceae and Asteraceae with 13 and 11 types, respectively, Apiaceae and Boraginaceae with five types each. Twenty-seven honey samples (65.85%) were found to be monofloral and the remaining 14 polyfloral. The pollen types from Ziziphus lotus, Peganum harmala, Echium sp., Tamarix sp., Lotus, Eucalyptus sp., Eruca vesicaria and Thapsia garganica appeared as the predominant pollen. Eighteen pollen types were classified as very frequent, present in more than 50% of the samples. The number of pollen types identified per sample ranged between 14 and 40 (mean of 24.41). For the quantitative analysis, the pollen content of the studied honey samples ranged from medium (class II, 48.78% of the samples) to high (class III, 53.65% of the samples), where the pollen density ranged from 26 607 to 660 992 in 10 g of honey, with an average of 160 880 grains per 10 g.

Ambophily in Olea ferruginea: a transitional state in the pollination syndrome

A number of plants species believed to be wind pollinated (anemophilous) are actually pollinated both by wind as well as insects (ambophily) because all the traits of the two pollination modes have not evolved simultaneously. Comparatively few angiosperms exhibit ambophily and the significance of such a mechanism is not fully understood. During the present investigation, ambophily was studied in Olea ferruginea, over a period of three years. It is an andromonoecious and out-crossing tree species of the olive complex. The species is predominately pollinated by wind because it shows fruit set even when the insect pollinators were excluded. Moreover, a substantial amount of pollen was observed on the body parts of insect visitors and, comparatively, fruit set was enhanced in open-pollinated flowers receiving insect visitors. Floral structure of O. ferruginea displays floral traits favoring both wind and insect pollination. Furthermore, the flowers of this species were found to be visited by 20 insect species classified under three orders with Diptera and Hymenoptera being the leading pollen foragers. The results of linear regression of the hanging slide experiment showed that the dispersal of pollen grains decreased significantly with increasing distance from the canopy and the pollen density increased significantly with an increase in insect activity. The present work provides an insight to understand the ecological and evolutionary adaptations and consequences of spatio-temporal variation in plant – pollinator interactions. It is, therefore, useful for addressing both basic and applied questions in community structure and function including the evolution of floral traits, reproductive assurance, and the development of optimal conservation strategies.

Recent Lateral Expansion of Sphagnum Bogs Over Central Fen Areas of Boreal Aapa Mire Complexes

We investigated recent changes in spatial patterning of fen and bog zones in five boreal aapa mire complexes (mixed peatlands with patterned fen and bog parts) in a multiproxy study. Comparison of old (1940–1970s) and new aerial images revealed decrease of flarks (wet hollows) in patterned fens by 33–63% in middle boreal and 16–42% in northern boreal sites, as lawns of bog Sphagnum mosses expanded over fens. Peat core transects across transformed areas were used to verify the remote sensing inference with stratigraphic analyses of macrofossils, hyperspectral imaging, and age-depth profiles derived from 14C AMS dating and pine pollen density. The transect data revealed that the changes observed by remote sensing during past decades originated already from the end of the Little Ice Age (LIA) between 1700–1850 CE in bog zones and later in the flarks of fen zones. The average lateral expansion rate of bogs over fen zones was 0.77 m y−1 (range 0.19–1.66) as estimated by remote sensing, and 0.71 m y−1 (range 0.13–1.76) based on peat transects. The contemporary plant communities conformed to the macrofossil communities, and distinct vegetation zones were recognized as representing recently changed areas. The fen-bog transition increased the apparent carbon accumulation, but it can potentially threaten fen species and habitats. These observations indicate that rapid lateral bog expansion over aapa mires may be in progress, but more research is needed to reveal if ongoing fen-bog transitions are a commonplace phenomenon in northern mires.