Pollen Quality Research Articles

QUALITY CHARACTERISTICS AND USE OF POLLEN: A LITERATURE REVIEW

Pollen is a natural product collected by bees and is rich in nutrients such as proteins, vitamins, minerals and antioxidants. It has been increasingly sought after by the natural food market for its benefits to human health. This study aimed to conduct a literature review on pollen, addressing: nutritional components, production and processing, quality analysis and applications in the food industry. The research methodology included the selection of sources, exploratory and selective reading, and recording of information. A systematic literature review was carried out in databases such as Scielo, Periódicos Capes, SB/UFCG, BDTD/USP, RI/UFS, BD/IPB, TEDE/UFMA published in the last 10 years (2012 to 2022). Forty-six national articles and 1 international article available online in full text were used. Information was obtained ranging from pollen collection to its applications in the food industry, which include the production of functional foods such as cereal bars, energy drinks and dietary supplements. The work also highlights the importance of pollen quality, including collection in areas free of pesticides and adequate storage. It also highlights the positive impacts generated by beekeeping and meliponiculture, reaching the three axes of sustainability: ecological, economic and social.

Elevational shifts in reproductive ecology indicate the climate response of a model chasmophyte, Rainer's bellflower (Campanula raineri).

Elevation gradients provide 'natural experiments' for investigating plant climate change responses, advantageous for the study of protected species and life forms for which transplantation experiments are illegal or unfeasible, such as chasmophytes with perennial rhizomes pervading rock fissures. Elevational climatic differences impact mountain plant reproductive traits (pollen and seed quality, sexual vs. vegetative investment) and pollinator community composition; we investigated the reproductive ecology of a model chasmophyte, Campanula raineri Perp. (Campanulaceae), throughout its current elevational/climatic range to understand where sub-optimal conditions jeopardise survival. We hypothesised that: 1) reproductive fitness measures are positively correlated with elevation, indicative of the relationship between fitness and climate; 2) C. raineri, like other campanulas, is pollinated mainly by Hymenoptera; 3) potential pollinators shift with elevation. We measured pollen and seed quality, seed production, the relative investment in sexual vs. vegetative structures and vegetative (Grime's CSR) strategies at different elevations. Potential pollinators were assessed by combining molecular and morphological identification. Whereas CSR strategies were not linked to elevation, pollen and seed quality were positively correlated, as was seed production per fruit (Hypothesis 1 is supported). The main pollinators of C. raineri were Apidae, Andrenidae, Halictidae (Hymenoptera) and Syrphidae (Diptera), probably complemented by a range of occasional pollinators and visitors (Hypothesis 2 partially supported). Potential pollinator communities showed a taxonomic shift towards Diptera with elevation (particularly Anthomyiidae and Muscidae) and away from Hymenoptera (Hypothesis 3 was supported). Pollinator availability is maintained at all elevations by taxon replacement. However, reduced pollen quality and seed production at lower elevations suggest an impact of climate change on reproduction (especially <1200 m a.s.l., where seed germination was limited). Aside from guiding targeted conservation actions for C. raineri, our results highlight problems that may be common to mountain chasmophytes worldwide.

Enhancement of bud dormancy release and development, leaf nutrition, flower and fruit quality of kiwifruit cv. ‘Hayward’ induced by BUD 14 biostimulant

The aim of this research was to investigate the influence of a foliar fertilization program, consisted of the BUD 14 nitrogen-calcium commercial formulation (N: 14% w/w, CaO: 5.5% w/w) as a biostimulant, on bud development percentage, flowering rate, classification of flowers into open, closed and triple, flower and pollen quality traits, fruit quality attributes, and leaf nutritional status of the ‘Hayward’ kiwifruit cultivar. The study was realized during a two-year experimental period in Naoussa, Central Macedonia, Greece. The results showed that BUD 14 induced synchronization in bud development relative to different vegetative stages including initiation of bud expansion, appearance of leaf apices covered by hair and deployment of 2-8 leaves and increased the flowering rate of open flowers. Pedicel length, ovary fresh weight, and dry weight, dry matter and length in female flowers as well as maximum pollen grain diameter and area in polar view in male flowers were significantly enhanced in the BUD 14 treatment. Fruit quality characteristics like average weight and dry mass were significantly augmented, and a 1.5-fold and 2-fold increase was recorded in canes length and number of kiwifruits per cane. In addition, leaf nutrient Ca and Mg concentrations were significantly enhanced, compared to the control. The efficacy of BUD 14 as a more target-oriented and environmentally friendly alternative method of supplying plants with smaller and controlled amounts of nutrients for breaking bud dormancy and improving their development was demonstrated, enhancing flower and fruit quality, leaf nutrition, kiwifruit developmental characteristics, and finally the total production per fruit per tree.

Physicochemical Characterization and Antioxidant Activity of Algerian Bee Pollens: Exploring Geographical Influences

Abstract: This research study offers a comprehensive physicochemical analysis and assessment of antioxidant activity for 15 bee pollen samples collected from diverse regions of Algeria. The analysis included a wide range of parameters such as moisture content, sugar composition (fructose, glucose, and sucrose), ash, electrical conductivity, free acidity, pH, total flavonoid (TFC) and phenolic (TPC) contents, as well as protein and lipid contents. Additionally, the study evaluated the antioxidant activity using two methods: DPPH radical scavenging activity and ferricreducing antioxidant power (FRAP).The results revealed higher values of pH, free acidity, and electrical conductivity, indicating potential variations in the physicochemical properties of bee pollen samples from different regions. Notably, the samples were further distinguished by high total phenolic content (26.23 mg GAE/g), flavonoid content (4.73 mg QE/g), and protein content (21.7%), along with a unique mineral composition. The analysis also demonstrated the highest total antioxidant capacity and a marked correlation with total phenolics. This study highlights the influence of geographical factors on the physicochemical properties and antioxidant activity of Algerian bee pollen. Regional variations underscore the importance of considering geographical factors in evaluating bee pollen quality, nutritional value, and potential health benefits of Algerian bee pollen. This emphasizes their crucial role in functional foods and natural health products. Understanding these variations supplies valuable insights for optimizing the utilization of bee pollen in functional foods, dietary supplements, and pharmaceutical formulations. Further research into environmental factors influencing bee pollen's antioxidant properties could enhance our understanding of its therapeutic potential. other: Further research into environmental factors influencing bee pollen's antioxidant properties could enhance our understanding of its therapeutic potential. Additionally, exploring the potential applications of Algerian bee pollen in functional foods, dietary supplements, and pharmaceutical formulations could provide opportunities for product development and innovation in the food and healthcare industries.

Blooming Phenograms, Pollen Production, and Pollen Quality during Storage of Pistachio Cultivars in New Mediterranean Growing Areas.

Pistachio (Pistacia vera L.) is a dioecious, anemophilous, and drought-resistant fruit tree species. It is cultivated in new Mediterranean areas, including the regions of southern Italy (Apulia and Basilicata). It has been estimated that over 40,000 ha are suitable for pistachio cultivation in areas infected by Xylella fastidiosa subsp. pauca. As a newly introduced species, knowledge of its biological reproductive behaviors in its new areas of spreading is essential for appropriate agronomic planning and management. This two-year study (2022 and 2023), carried out in the countryside of Stigliano (MT, Italy), had the objective of evaluating the flowering phenograms, pollen production, and assessing protocols for the conservation and extension of pollen viability, of the most widespread cultivars. A slight delay was observed in the blooming phenograms, compared to other cultivation Mediterranean areas, such as Spain or Sicily. Furthermore, the overlap between female and male phenograms was partial. No significant differences were observed in the polliniferous aptitude of the two male cultivars. Among the different protocols tested, the pollen storage at 33% relative humidity and a temperature of -80 °C maintained the pollen germinability above 50% for up to three weeks. These findings highlight the importance of controlled environmental conditions in preserving pollen viability over extended periods, providing valuable insights for agricultural and botanical research that relies on maintaining pollen viability for breeding and genetic studies.

Effects of classical and organomineral fertilizer applications on pollen quality and quantity in gemlik olive cultivar

Olive is one of the important plants worldwide in terms of economic and cultural conditions. It is used in fresh consumption, olive oil, cosmetic and pharmaceutic fields and unique numinous plants. Olive can maintain its life for many years even in barren conditions but for an economic cultivation, fertile and preferred cultivars should be used in orchards and optimum maintenance conditions should be provided. At the same time the climate change is also convert the usual behavior of the plants. This study aims to determine the effects of classic and organomineral fertilizers on pollen quality and quantity parameters. In this study, classical fertilizers like Urea+MgSO4 and KNO3+H3BO3+ZnSO4 with Raykat Start, Raykat Growth and Fitomare organomineral fertilizers were sprayed foliarly before flowering on Gemlik olive cultivar and pollen studies were conducted on the flowers formed at full flowering. Within the study, effects of the treatments were evaluated on pollen viability and germination levels, the amount of pollen produced in one flower and the normally developed pollen ratio. As a result of this study, fertilization treatments positively affected pollen quality and quantity with regard to control treatment. In this context, the pollen viability level differed between 74.15% and 89.92%, the pollen germination level between 45.48% and 70.35% and pollen per flower was between 307.238 and 446.761. The lowest data were obtained from control treatments, while the highest were from Raykat group fertilizers. Especially, the 54% increase in pollen germination level with Raykat growth fertilization was one of the most important results of this study. In conclusion, it was determined that the foliar spray of organomineral fertilizers enhanced the pollen properties. Raykat Start, Raykat Growth and Fitomare organomineral fertilizers used in this study significantly increased pollen quality and quantity.

Do past and present abiotic conditions explain variation in the nutritional quality of wildflower pollens for bees?

Do past and present abiotic conditions explain variation in the nutritional quality of wildflower pollens for bees?

Co-flowering richness has variable effects on pollen quantity and quality limitation in four Clarkia species.

Pollination failure occurs from insufficient pollen quantity or quality. However, the relative contributions of pollen quantity vs quality to overall pollen limitation, and how this is affected by the co-flowering context, remain unknown for most plant populations. Here, we studied patterns of pollen deposition and pollen tube formation across populations of four predominately outcrossing species in the genus Clarkia to evaluate how richness of co-flowering congeners affects the contribution of pollen quantity and quality to pollen limitation. We partition variation in pollen deposition and pollen tube production across individuals, populations and species to identify the main sources of variation in components of reproductive success. We further quantify the relative contribution of pollen quantity and quality limitation to the reproductive success of the four Clarkia species using piecewise regression analyses. Finally, we evaluate how variation in the number of co-flowering Clarkia species in the community affects the strength of pollen quality and quality limitation. Across all contexts, pollen deposition and the proportion of pollen tubes produced varied greatly among individuals, populations, and species, and these were not always correlated. For instance, C. xantiana received the smallest pollen loads yet produced the highest proportion of pollen tubes, while C. speciosa exhibited the opposite pattern. Yet, co-flowering richness had variable effects on the strength of pollen quantity and quality limitation among populations. Specifically, breakpoint values, which are an indicator of overall pollen limitation, were two times larger in the four-species community compared with one and two-species communities for two Clarkia species, suggesting that pollen limitation can increase with increasing richness of co-flowering congeners. Our results reveal a complex interplay between quantity and quality of pollen limitation and co-flowering context that may have different evolutionary outcomes across species and populations.

Effects of N, P and K fertilizations on bud nutrient concentrations and fruit set of sweet cherry trees

Factors such as pollinators, pollen quality, pollinator variety, high temperatures, and nutrients affect the fruit set in sweet cherry trees. In this study, the effects of different doses of N, P, and K applied from the soil on fruit set of sweet cherry were investigated. Flower bud minerals (N, P, K, Ca, Mg, Fe, Cu, Mn, Zn, and B), fruit set ratios (FSR), and yield values were determined to compare treatments for 3 years (2015–2017). FSR (%) and yield (kg/tree) values ​​ranged between 14.31–21.76 and 11.11–14.88 for N, 11.94–22.64 and 11.23–14.82 for P, 12.38–17.39 and 12.67–13.68 for K, respectively. N affected fruit bud N, Mg, Fe, Mn, and B concentrations, FSR and yield. Parameters other than FSR increased with increasing N doses and the highest values ​​were obtained from the highest N treatment. FSR of the highest N dose was the same as the control treatment, but lower in the other treatments. P affected fruit bud P and Mg concentrations, FSR and yield. Fruit bud P and Mg concentrations increased as compared to the control treatment. The change in FSR and yield values ​​could not be associated with the application dose, but showed linear changes with each other. K was effective only on FSR, the lowest values ​​were obtained at the highest dose, while it was similar at the other doses. Fruit set ratio of sweet cherry trees under present experimental conditions could not be associated with the change in fruit bud nutrients due to N, P and K fertilization.

Floral visitors, pollinators and floral rewards of the Australian dioecious arid zone shrub Pimelea microcephala subsp. microcephala

ABSTRACT Entomophilous dioecious plants may present opportunities to conserve insect populations as they often possess flowers accessible to a diversity of visitors and potential pollinators. Additionally, flowers of each sex can vary in the nutrients they provide. Two South Australian populations of the largely dioecious arid zone shrub Pimelea microcephala subsp. microcephala (Thymelaeaceae) were investigated to determine the conservation utility of the species to conserve insect populations by assessing floral visitor and pollinator diversity and the nutritional quality of pollen and nectar. Fifty-five visitors representing species in six insect orders were recorded at Baron Station, while 49 visitors from three insect orders were recorded at Clements Gap. Thirty-nine of the observed visitors were captured, of which two species of Hymenoptera, two of Diptera and one of Hemiptera were carrying pollen and thus potential pollinators. Visitation rates were higher for male than female plants at Clements Gap, but the reverse at Baron Station. Pollen from male plants had low protein content (2.5% dried weight (DW)) compared to co-flowering hermaphroditic angiosperms at the sites (5.3–14.0% DW). In contrast, floral extracts from male plants had at least 2× greater cumulative sugar concentrations than those of females at the same site, but female extracts had at least 4× higher protein content than male ones. As a food resource plant, P. microcephala subsp. microcephala may represent an important plant species for revegetation efforts that support the conservation of insect diversity in arid regions and throughout its broad range.

Семенная продуктивность и качество семян Pinus sylvestris L. в лесных культурах на крымских яйлах

The seed production and quality of Pinus sylvestris seeds in forest plantations on the Crimean yaylas has been studied. The dynamics of biometric indicators of cones and seeds by year and in connection with the peculiarities of growing conditions has been characterized. Significant differences in the quality of seeds of P. sylvestris trees have been revealed in terms of the level of germination energy. It has been shown that, along with the temperature regime, a significant impact on the effectiveness of P. sylvestris reproduction processes is exerted by air humidity and the nature of precipitation, as well as the dynamics of air mass movement, since the success of pollination is determined by the quantity and quality of pollen that has reached the female reproductive structures. Based on the analysis of weather phenomena and the dynamics of seed quality, it has been found that the level of seed germination is best reflected by an integrated index that takes into account the combined effect of several factors – the dryness index. In addition, the results of the analysis allowed us to conclude that the efficiency of the pollination process of female cones of P. sylvestris under yayla conditions is most likely influenced by the number of hours of sunshine. The germination energy and seed germination differ not only within the studied plantations, but also depending on the year of study. During the observation period, the forest plantations of the Ai-Petrinskaya Yayla have produced the highest quality seeds. In 2014, in the plantations with a density of 0.5, the seed germination rate was 74.5±2.2 %. The lowest level of germination energy and seed germination has been noted in artificial plantations of P. sylvestris on the Tirke Yayla; in 2012, these indicators here amounted to 15.2±0.7 and 46.2±2.1 %, respectively. In general, the development of the generative sphere of P. sylvestris in artificial plantations on the Crimean yaylas is quite effective. Based on this, a conclusion has been made that the growing conditions on the yaylas are favourable for the implementation of the initial stages of the ontogenesis of the species.

Influence of temperature conditions of the environment on the dynamics of collecting bee pollen and flower pollen by honey bees

The study conducted at the apiary of the National Scientific Center «P.I. Prokopovych Institute of Beekeeping» in Hadiach, Poltava region, from 2021 to 2023 investigates the dynamics of bee pollen collecting by honey bees of the Ukrainian steppe breed of the Hadiach type. This research focuses on understanding how weather conditions in the forest-steppe zone impact the mass, volume, and size of bee pollen, as well as the botanical composition of the collected pollen. The primary objective of this research is to analyze how different weather conditions influence the collection of bee pollen by honey bees. Specifically, the study aims to assess how variations in temperature, humidity, and other weather factors affect the quantity and quality of pollen collected, and how these factors interact with the flowering periods of key nectar plants. The study utilized hanging pollen collectors to gather pollen from bee colonies between 8 AM and 2 PM. The botanical origin of the pollen was determined through microscopic analysis and international palynological databases. The research focused on several common nectar plants, including red clover (Trifolium pratense), common primrose (Primula vulgaris), cornflower (Centaurea cyanus), common agrimony (Agrimonia eupatoria), field thistle (Cirsium arvense), and common burdock (Carduus acanthoides). Weather conditions were classified into favorable (temperatures of 18–25°C and relative humidity of 57–72%) and unfavorable (cloudy days with northern winds, temperatures below 15°C or above 28°C, and humidity levels outside the 57–72% range). The research revealed that the average mass of bee pollen collected per season varied between 6.3 and 6.6 kg per bee colony. The study found that different plants responded differently to weather condi­tions. For instance, the mass of pollen from red clover ranged from 8.3 to 12.0 mg under favorable conditions, while field thistle showed a decrease in pollen mass during unfavorable conditions. Pollen collection began in mid-April and continued until mid-August. During unfavorable weather conditions, there was a noticeable reduction in pollen mass, which was attributed to lower pollen availability. However, some plants showed better pollen production under adverse conditions. The spring peak in pollen collection, associated with active colony growth, was also influenced by the less diverse summer flora. Temperature data for 2021–2023 indicated that the most favorable conditions for pollen collection varied annually. For example, the cool spring of 2021 delayed bee colony development, while 2022 experienced normal weather conditions. In contrast, 2023 saw active pollen collection during acacia blooming but a reduction duringlime blooming due to insufficient pollen. The study underscores the importance of considering a comprehensive range of weather conditions when evaluating bee colony productivity. The findings highlight that both temperature and humidity significantly impact pollen collection. The results suggest that beekeepers need to account for these variables in their management practices to optimize pollen collection. Further research should explore the interactions between different weather factors and their combined effects on bee foraging behavior and pollen production. Additionally, studies could investigate how changes in climate over longer periods affect bee colony performance and pollen dynamics, providing insights for developing adaptive strategies in beekeeping.

Determining appropriate methods for estimating pollen viability and germination rates in lisianthus

Crossbreeding is a multi-stage process with inherent challenges and risks in developing new varieties. Success hinges on selecting highly fertile parents. In species like lisianthus, uncertainty persists regarding the optimal methods for assessing pollen quality, which is crucial for evaluating pollen parent fertility. This study seeks to identify the most reliable techniques for this purpose. Fresh and dead pollen from four lisianthus (Eustoma grandiflorum) varieties was used. The dead pollen was obtained by thermal inactivation. Five chemical staining methods (iodine-potassium iodide, 2,3,5-triphenyltetrazolium chloride – TTC, lactophenol cotton blue, safranin, acetocarmine) were employed to assess pollen viability, and two biological methods (Petri dishes, hanging drops) were used to determine the germination rate. Four solid medium cultures were employed in Petri dishes, while the hanging drop utilised four liquid medium cultures. Thirteen tests were conducted for each variety, evaluating fresh and dead pollen. The study found significant variations in pollen quality among lisianthus varieties and methods. Fresh pollen showed viability rates ranging from 56.87% to 99.41% and germination rates from 0.20% to 45.11%. TTC exhibited the lowest viability rate across all varieties, while the highest germination rate was observed in the liquid culture medium with only boric acid and PEG1500. Notably, TTC was the sole viability method that did not stain dead pollen, and no germination occurred in any method for dead pollen. TTC is the most reliable staining method, and a liquid culture medium with boric acid and PEG1500 effectively determines lisianthus pollen quality. Varying boric acid and PEG1500 concentrations are advisable.

Honey bee protein and lipid nutrition in avocado and blueberry agroecosystems with conventional and organic management

Honey bees play a crucial role in agricultural production. Farmers rely on commercial bee pollination to obtain optimal yields, and beekeepers on the income from pollination fees. However, commercial pollination confronts honey bees with pests and pathogens, pesticides, and low-quality food, which in many cases do not fulfill the minimal nutritional requirements of honey bees. In this work, we evaluated honey bee nutrition in avocado and blueberry plantations under organic and conventional management, by assessing the nutritional quality of pollen and bee bread based on their protein, fatty acid, and microbial content, and by analyzing honey bee health through the examination of abdominal fatty acid profiles and head protein content. Low protein content in honey bee hemolymph was evident under conventional management. Regardless of management, avocado pollen showed higher protein levels, which were translated into higher honey bee head protein levels being 60% higher in avocado under conventional management when compared to blueberry under the same management. However, higher protein levels in avocado pollen were also translated into lower amounts of fatty acids in bee bread and in honey bee fat. In particular, the total amount of fatty acids in bee bread from conventional management was 50% lower than that from organic management. Additionally, the saturated fatty acids in conventional blueberries were lower compared to that of organic blueberries. Crop system and bee bread microbial composition altered the plant-honey bee nutrition cascades transforming pollen to bee bread with increased amount of saturated, unsaturated, and total fatty acids. In conclusion, both crop species and crop systems determine honey bee nutrition through alterations in the pollen transformation, affecting protein and fatty acid assimilation.

PENGARUH WAKTU PENYERBUKAN TERHADAP KUALITAS HASIL TANAMAN MELON (Cucumis melo L) DENGAN PERKAWINAN SILANG TANAMAN SEMANGKA (Citrullus vulgaris L)

Decreased production of melon (Cucumis melo L) which is due to constraints in fruit quality decreases due to the ability of fruit formation is naturally low due to a failure in the process of pollination. The success of pollination it self is influenced by the maturity of the male flowers and female flowers itself. Therefore we need a suitable time to perform pollination to see the stigma receptivity and pollen viability at the same level. To overcome these problems need to develop crops melon (Cucumis melo L) through the technique of cultivation is called plant breeding to obtain the production of melon (Cucumis melo L) qualified by determining the time of pollination and crossed with a watermelon (Citrullus vulgaris L). This research is experimental research design using a randomized block design (RAK) 1 factor with 5 treatment combinations and each treatment using 10 replications. The treatment factors are as follows: PA = at 05:00 to 06:00, PB = at 07:00 to 08:00, PC = at 09:00 to 10:00, PD = at 11 : 00 to 12:00 and PE = at 13:00 to 14:00. The data were collected and presented in tables and statistical analysis of test One-Way ANOVA (Analysis Of Variance). If there is a real difference followed by testing of LSD (Least Significant Difference) (p &lt;0.05). Statistical analysis One-Way ANOVA test and LSD show that there is the influence of pollination time on the fruit weight, average fruit diameter and weight of seed resulting from cross-breeding melon (Cucumis melo L) and watermelon (Citrullus vulgaris L). Data show that the PA treatment is the best treatment compared with other treatments. This happens Because the quality of pollen in the morning are of better quality compared to during the day so that pollen powderd in the morning better able to fertilize the pistil to the maximum.

Variation in pollen viability among Leptochloa crinita accessions: implications for directed crosses

ABSTRACT Leptochloa crinita, a native forage grass from American arid regions, is widely used for range grazing and revegetation of degraded lands. Despite its importance, progress in breeding and genetic research has been hindered by the difficulty of achieving sexual crosses between L. crinita plants. We hypothesize that factors associated with pollen quality can influence the effectiveness of directed sexual crosses in this species. Thus, the present study investigated pollen viability and longevity in a genetically diverse collection of 21 L. crinita accessions. Pollen viability was estimated at 0, 30, 60, and 180 minutes after anthers dehiscence (MAAD) by two methods: 1) acetocarmine staining; and 2) in vitro germination of pollen grains in culture media containing 0.4-1.0 M sucrose. The staining method overestimated pollen viability, whereas the in vitro germination assay provided accurate and reliable estimates, being 0.6 M the optimal sucrose concentration in the medium, in terms of germination rates and discriminatory power among the accessions. In all the accessions, pollen viability was highest at 0-30 MAAD, and decayed very rapidly, to reach levels below 5% at 180 MAAD. Significant (p<0.05) and broad variation for pollen viability was found among the accessions, with mean values in the range of 49-89% (0 MAAD), 32-76% (30 MAAD), 24-45% (60 MAAD), and 0.6-4.9% (180 MAAD), allowing the identification of six accessions exhibiting the greatest pollen viabilities. These results suggest 0-30 MAAD and using the selected (best) pollen donors, on emasculated female parentals, as the optimal conditions for attempting sexual crosses in L. crinita.

Honey bee (Apis mellifera L.) foraging rewards in sunflowers: effect of floral traits on visitation and variation in pollen quality over two consecutive years

Sunflower production depends on pollination by honey bees, Apis mellifera L., and wild bees. For wild sunflower oligoleges, preference for various sunflower lines seems to reflect the quantity (or accessibility) of floral rewards, with floret size (≈accessibility of sunflower nectar) appearing most important. However, it is less clear how honey bees, a key generalist, are affected by sunflower floral traits. The honey bee-sunflower interaction was explored to test if accessibility of nectar (≈floret size) and related floral traits explain foraging preferences and to assess potential nutritional variation in sunflower pollen. In the first two years, honey bee foraging preference increased with decreasing floret length similar to previous observations with wild pollinators. In the second year, no similar response was seen, though nectar rewards (by volume or volume × concentration) were remarkably low compared to the previous year. Pollen collected from bagged plants in the second year showed sunflower lines differed in concentrations (µg/mg ± SE) of total fatty acids and essential fatty acids. In general, it appears that honey bee responses to floral traits are similar to those of wild bees responsible for pollinating much of the sunflower crop in the central United States and that variation in the nutritional quality of sunflower pollen is greater than previously known. Because of the broad geographic distribution of the sunflower crop, additional research on how the environment influences floral rewards and sunflower-pollinator interactions may be needed.

The Key Role of Amino Acids in Pollen Quality and Honey Bee Physiology-A Review.

When studying honey bee nutrition, it is important to pay attention not only to the quantity but also to the quality of pollen for floral visitors. The recommended way to determine the value of pollen is to determine both the protein concentration and the amino acid composition in the insect's hemolymph. In addition, the composition of pollen also includes lipids, sterols and biogenic elements such as carbon, nitrogen, etc. Very high protein concentration is observed in aloe pollen, averaging 51%. Plants with a high protein content, at the level of 27% in Europe, are rapeseed and phacelia. In turn, a plant that is poor in protein (at the level of 11%) is buckwheat. The aforementioned plants are sown over very large areas. Vast acreages in Central and Eastern Europe are occupied by pollen- and nectar-providing invasive plants, such as goldenrod. Therefore, bees are forced to use one food source-a mono diet-which results in their malnutrition. In the absence of natural pollen, beekeepers use other foods for bees; including soy protein, powdered milk, egg yolks, fish meal, etc. However, the colony is the strongest when bees are fed with pollen, as opposed to artificial protein diets. More research is needed on the relationship between bee pollen composition and nutrition, as measured by protein concentration and amino acid composition in apian hemolymph, colony strength, honey yield and good overwintering.

Пыльцевой анализ линий селекционно-генетической коллекции подсолнечника

We studied pollen productivity and its morphological heterogeneity in the lines of the breeding and genetic sunflower collection. The research was carried out at the V.S. Pustovoit All-Russian Research Institute of Oil Crops, Krasnodar, in 2022–2023. Collection lines VK934, VK1-klp, VK678, VK876, In Krupnyak, VK195, MVG-8, VK416, L2138, K1587, KG49 and RIL200 were used. To assess the quality of pollen, we used the parameter of morphological heterogeneity of pollen grains, i.e. the proportion of atypical grains. The pollen productivity was assessed by two parameters: pollen weight and the number of pollen grains. A Biolab TS-2000 LCD MS 20 microscope was used at a magnification of 40×. A line L2138 was characterized by a maximum weight of 1.17 mg/anther and a number of pollen grains of 45,239 pieces/anther. A line VK876 had the minimal values of these traits – 0.25 mg/anther and 16448 pcs/anther, respectively. A high positive correlation of r = 0.90 was noted between these traits. In 2022, the average diameter of pollen grains in 12 studied lines varied from 30 to 32 µm, with an average value of 31 µm. In 2023, the minimal diameter of pollen grains was lower than in 2022 and amounted to 27 µm, the maximum was at the level of 2022 – 32 µm with an average value of 30 µm. Over two years of research, a line KG49 showed significant morphological heterogeneity of pollen, which was expressed in a high proportion of defective pollen grains (58%). A line VK195 was characterized by low morphological heterogeneity with a proportion of defective pollen grains of 5%.

Phenotypic selection patterns in a hybrid zone between two Calceolaria species with contrasting pollinators: insights from field surveys and fitness assessments.

Hybrid zones provide natural experimental settings to test hypotheses about species divergence. We concentrated on a hybrid swarm in which oil-collecting bees and flower-pecking birds act as pollinators of two Calceolaria species. We asked whether both pollinators contributed to flower divergence by differentially promoting prezygotic fitness at the phenotypic extremes that represent parentals. We studied pollinator-mediated selection on phenotypic traits critical in plant-pollinator mechanical interaction, namely plant height, reward-to-stigma distance, and flower shape. We utilised the quantity and quality of pollen deposited as fitness measures and distinguished between the contribution of the two pollinator types. Results showed uni- and bivariate disruptive selection for most traits through pollen grains deposited by both pollinators. Bird-mediated fitness favoured low plants with a long reward-to-stigma distance and a straight corolla, while bee-mediated fitness favoured tall plants with a short reward-to-stigma distance and curved corolla. In addition, stabilising selection at one end of the phenotypic range showed a bird-mediated reproductive asymmetry within the swarm. The disruptive pattern was countered, albeit weakly, by hybrids receiving higher-quality pollen on the stigmas. Results suggest that pollinator-mediated selection promotes divergence of integrated flower phenotypes mechanically adjusted either to bees or birds underscoring the importance of pollinator specialisation in diversification.