Onion Flower Research Articles

Onion (Allium cepa L.) Attracts Scoliid Wasps by Means of Generalist Floral Volatiles.

Onion flowers require pollinator-mediated cross-pollination. However, the cues that pollinators use to locate the flowers are not well understood. The floral scent, along with floral visual cues, might acts as important signal to pollinators in order to locate the floral resources. We used electrophysiological methods combined with behavioural assays to determine which compounds in a floral scent are more attractive and thus biologically important to foraging scollid wasps. The majority of the molecules identified as floral fragrances in onions are common compounds that are already known from other angiosperms, and onion floral scents were predominately composed of aromatic components. The antennae of scoliid wasps responded to a large number of compounds, among them o-cymene, cis-β-ocimene, benzaldehyde and allo-ocimene were behaviourally active. In contrast to other wasp flowers investigated nectar analysis demonstrated the dominance of hexose sugars over sucrose. Our findings provide fresh insights into the floral volatile chemistry of a key vegetable crop grown around the world. We demonstrate here that onion is using generalist floral volatiles to attract floral visitors. This insight could be utilised to make onion blooms more attractive to minor pollinators as well as major pollinators in order to maximise seed set.

Onion flower stalks: Its physicochemical, bioactive, and antioxidant characteristics as affected by thermal processing

Consuming vegetables is linked to health benefits. Onion flower stalk (OFS) is a green vegetable with a mild onion flavor and is widely consumed in South Asia. The objectives of this study were to evaluate and understand the effect of boiling time (5, 10, 15, and 20 min at 100 °C) on physicochemical, bioactive compounds, and antioxidant activity of OFS. After boiling, moisture content and pH increased, whereas total soluble solids, water activity, titratable acidity, and ascorbic acid content decreased with increasing boiling time. The ascorbic acid content of fresh OFS was 20.59 mg/100 g fresh weight (FW), which decreased by 71.45 % after 20 min of boiling. The total phenolics, flavonoids, and tannin content in fresh OFS were 517.16 mg GAE/kg FW, 341.55 mg QE/kg FW and 517.28 mg TAE/kg FW, respectively. However, prolonged boiling caused a damaging effect on these bioactive compounds. It was observed that 20 min of boiling caused about 55.50 % loss in total phenolic, 58.44 % loss in total flavonoids, and 55.88 % loss in total tannin. The decrease in antioxidant capability was associated with the depletion of phytochemicals. The results also demonstrated that the ethanolic extract of OFS was effective in DPPH free radical scavenging activity. For extended boiling, the IC50 values rose gradually, indicating a decrease in antioxidant activity. Kinetic modeling showed that a first order model could more accurately anticipate changes in ascorbic acid and bioactive components with a higher R2. Findings from this research would be useful in designing thermal processing equipment for fruits and vegetables.

From petals to seeds: Understanding the role of hymenopteran and dipteran pollinators in the reproductive success of onion (Allium cepa L.)

An experiment was conducted to assess the pollinator community of onion (Allium cepa L.) as well to find the pollinators contributing to a higher onion seed production. Fifteen insect pollinator species belonging to two orders and two families were found to be visiting onion flowers. The dwarf honeybee, Apis florea F. (Hymenoptera: Apidae) was most frequent pollinator among bees. The maximum visitation rate was recorded in the case of Eristalinus aeneus S. (Diptera: Syrphidae), while the maximum stay time was recorded for A. florea. For observing the pollination effectiveness, we used pollinator exclusive approach, and four pollination trials were maintained i.e., 100%, 50%, 25% and 0% pollination. Pollinator effectiveness was accessed in terms of yield parameters such as umbel weight, number of seed and seed weight. Compared to 0% pollination, plants with 100% and 50% pollination levels showed 44- and 19-times higher seed production in onion, respectively. Six major pollinators were tested for their pollination efficiency. The single visit efficiency in terms of the number of seeds showed that plants with A. florea pollination showed higher seed yield. There was an increase in the number of seeds and seed weight per umbel, proving that A. florea is an effective pollinator in onion production. Moreover, syrphid flies also contributed to the onion seed production, though they were less efficient pollinators.

Cloning and Expression Analysis of Onion (Allium cepa L.) MADS-Box Genes and Regulation Mechanism of Cytoplasmic Male Sterility.

Flower organ development is one of the most important processes in plant life. However, onion CMS (cytoplasmic male sterility) shows an abnormal development of floral organs. The regulation of MADS-box transcription factors is important for flower development. To further understand the role of MADS-box transcription factors in the regulation of cytoplasmic male sterility onions. We cloned the full-length cDNA of five MADS-box transcription factors from the flowers of onion using RACE (rapid amplification of cDNA ends) technology. We used bioinformatics methods for sequence analysis and phylogenetic analysis. Real-time quantitative PCR was used to detect the expression patterns of these genes in different onion organs. The relative expression levels of five flower development genes were compared in CMS onions and wild onions. The results showed that the full-length cDNA sequences of the cloned MADS-box genes AcFUL, AcDEF, AcPI, AcAG, and AcSEP3 belonged to A, B, C, and E MADS-box genes, respectively. A phylogenetic tree construction analysis was performed on its sequence. Analysis of MADS-box gene expression in wild onion and CMS onion showed that the formation of CMS onion was caused by down-regulation of AcDEF, AcPI, and AcAG gene expression, up-regulation of AcSEP3 gene expression, and no correlation with AcFUL gene expression. This work laid the foundation for further study of the molecular mechanism of onion flower development and the molecular mechanism of CMS onion male sterility.

Flowers of Allium cepa L. as Nutraceuticals: Phenolic Composition and Anti-Obesity and Antioxidant Effects in Caenorhabditis elegans.

Allium cepa L., commonly known as onion, is one of the most-consumed vegetables. The benefits of the intake of its bulb are well studied and are related to its high polyphenol content. The flowers of onions are also edible; however, there are no studies about their biological properties. Our aim was to determine the polyphenolic profile and assess the antioxidant and anti-obesity capacity of an ethanolic extract from fresh flowers of A. cepa. The phenolic constituents were identified through LC-DAD-ESI/MSn. For the anti-obesity potential, the inhibitory activity against digestive enzymes was measured. Several in vitro assays were carried out to determine the antioxidant capacity. A Caenorhabditis elegans model was used to evaluate the effect of the extract on stress resistance and fat accumulation. For the first time, kaempferol and isorhamnetin glucosides were identified in the flowers. The extract reduced fat accumulation in the nematode and had a high lipase and α- glucosidase inhibitory activity. Regarding the antioxidant activity, the extract increased the survival rate of C. elegans exposed to lethal oxidative stress. Moreover, the activities of superoxide dismutase and catalase were enhanced by the extract. Our results demonstrate, for the first time, the antioxidant and anti-obesity activity of onion flowers and their potential use as functional foods and nutraceuticals.

Role of Entomophily and Artificial Pollination in Enhancing Quality and Yield of Seed Onion (Allium cepa L.) in Indian Himalayas

Abstract Onion (Allium cepa L.) is a highly cross pollinated crop that needs insect pollination (entomophily) for optimum seed set. In the present study, more than 120 insect species were noted to visit onion flowers, out of which fifty-nine species were collected through in-situ sampling technique and identified up to species level. The Indian bee (Apis cerana indica) was the most abundant insect pollinator visiting onion flowers in the study location. The pollination behaviour and foraging activity of A. c. indica were assessed, and the pollen foragers were observed to be swift flyers visiting a significantly higher number of flowers per minute during the peak flowering period and spending less time per flower (3 seconds) to collect nectar from deep seated nectaries of the flowers. The seed yield enhancement assessed through entomophily and artificial pollination methods showed that the open pollinated flowers recorded the highest yield statistically, followed by A. c. indica and A. mellifera pollinated flowers. However in artificial pollination treatments, sponge puff pollinated flowers recorded significantly high seed yield per hectare and percentage seed set per umbel, followed by camel brush, hand gloves (cloth) and hand gloves (rubber). In conclusion, all the cross pollination treatments were statistically significant on the closed pollination treatment concerning to the entire yield parameters calculated.

Pollination efficiency and foraging behaviour of honey bees and flies to onion Allium cepa L.

Bees and flies are the most common visitors to onion flowers in Karnataka, but evidence for their pollination efficiency is lacking. Hence, experiments on pollination efficiency and behavioral observations were recorded using four bees (Apidae: Hymenoptera) and two flies (Syrphidae: Diptera) species visiting onion flowers (Allium cepa L.) at the experimental fields of ICAR-Indian Institute of Horticultural Research, Bengaluru, Karnataka, India (13.13°N; 77.49°E) during 2020-2021. Pollinator effectiveness (PE) is measured as pollen deposition on stigmas per visit. Honey bees and flies mainly collect nectar and stingless bees mainly pollen (81.90%), bringing the latter into intimate contact with the stigma more frequently. Stingless bees, honey bees and flies were often seen foraging together on the same umbel, and no antagonistic interactions were observed. The rock bee (Apis dorsata) deposited a maximum number (34.60) of pollen on stigma per visit followed by the stingless bee (24.45). The flowers pollinated by bees had a higher seed set percentage; the weight of 1000 seeds and the average number of seeds/umbels were higher compared to flowers deprived of pollinators. The results allowed us to conclude that bees are the effective pollinators of onions. Further work is needed to determine the optimum bee population required for maximizing the seed yield in onion.

Diversity and foraging behaviour of floral visitors assemblages in onion Allium cepa L.

Anthophilous insects are of key importance for onion reproduction due to the protandrous nature of flowers, related to inbreeding avoidance. We documented the diversity of floral visiting insects on onion flowers at the ICAR-Indian Institute of Horticultural Research, Bengaluru, Karnataka, India, during 2019-21. The pollinator community is composed of thirty hymenopteran species, sixteen dipteran species, eight lepidopteran species, four hemipteran species, and one species from Coleoptera. From these, Hymenoptera and Diptera contributed >75% of the floral visitors. The majority of the floral visits by the anthophilous insects were for collecting nectar (81.59%) followed by nectar as well as pollen foraging (9.97%) and only pollen (8.44%). The proportion of stigma contact did not depend on the body size of the floral visitor. However, stigma contact depends on whether floral visitors collected nectar or pollen and also on the head width of the floral visitor. The present study helps to understand the pollination efficiency of pollination candidates for onion. Further, there is a need to study the pollen harvest and effective stigmatic pollen deposition by the floral visitors.

The novel dual-category active sites of NiCoP/CoP as high-performance electrocatalyst for urea electrolysis and synergistic hydrogen production

The novel 3D “Fistular onion flower” CNCP-350 benefits from the abundance of dual-category activity sites, demonstrating an excellent efficient catalytic performance in UOR and HER.

EDIBLE ONION FLOWERS (ALLIUM L.) AS A SOURCE OF BIOLOGICALLY ACTIVE SUBSTANCES

The results of comparative study of the content of biologically active substances in the flowers of 10 species of perennial onions Allium aflatunense B. Fedtsch., A. altaicum Pall., A. flavum L., A. microdictyon Prokh., A. nutans L., A. obliquum L., A. ramosum L., A. rosenbachianum Regel, A. schoenoprasum L., A. senescens L. var. glaucum Regel (A. senescens ssp. glaucum (Schrad.) N. Friesen) are presented. The freshly collected raw materials in the phase of mass flowering were analyzed. The dry matter content was determined by drying 1 g of raw material at 100–105 °C to a constant mass. The amount of phenolic compounds, pectin substances, total sugars, and carotenoids was determined spectrophotometrically using SF-56 (Russia) and SF "Agilent" 8453 (USA). For the first time, data on the quantitative content of the main groups of secondary metabolites in onion flowers were obtained. It has been established that in the forest-steppe of Western Siberia, flowers of Allium species contain: 10.7-22.5% dry substances, 6.6-26.2% total sugars, 3.3–18.6% pectin substances, 3.6–10.6% phenolic compounds, 3.0–23.4 mg% carotenoids (per mass of absolutely dry materials) and 35.4–157.8 mg% ascorbic acid (per mass of raw materials). The highest values were found for A. rosenbachianum, A. flavum, and A. aflatunense. The high variability of the accumulation of biologically active substances is due to the species and the influence of weather conditions during the growing season. The study showed the prospects for using onion flowers as a source of various bioactive compounds, including when added to food.

Antagonistic Activities of Endophytic Fungi Isolated from Eleutherine palmifolia Flower

<b>Background and Objective:</b> Endophytic fungi live in plant tissue and show no symptoms of disease in their host plants. It is known that endophytes as biological agents, can control plant diseases. In this study, isolated endophytic fungi from healthy Dayak Onion flowers were used as biocontrol agents in the control of the pathogenic fungi <i>Fusarium </i>spp. that causes molar disease in shallot plants. <b>Materials and Methods:</b> This study identifies the type of endophytic fungi molecularly isolated from Dayak onion flowers and determine the antagonistic effect of the endophytic extract against <i>Fusarium </i>spp. screening for endophytic fungi as antagonizing agents is carried out using the poisoned food method. <b>Results:</b> The results showed that two endophytic fungi isolates were obtained from healthy Dayak onion flowers, namely, EnI which was identified with the primers ITS1 and ITS4 as <i>Fusarium solani</i> and EnK as <i>Neoscytalidium </i>sp. <i>Fusarium</i> wilt caused by pathogenic fungi was identified as <i>Fusarium oxysporum</i>. The inhibitory percentage of EnI extract against the pathogenic fungus <i>Fusarium oxysporum</i> was 71.09% (high inhibition percentage) and the inhibition percentage of EnK was 38.54% (low inhibition percentage). <b>Conclusion:</b> Based on the results of this study, recommend using the endophytic fungus EnI extracts (<i>Fusarium solani </i>), extracted from Dayak onion flowers to control the pathogen <i>Fusarium oxysporum</i>.

Potensi Cendawan Endofit dari Bunga Bawang Dayak untuk Menekan Pertumbuhan Ralstonia solanacearum pada Tanaman Tomat

Cultivation of tomato plants (Lycopesicum esculentum Mill.) Is often exposed to plant diseases. One of the diseases that often attacks tomato plants is bacterial wilt disease caused by R. solanacearum. Therefore, it is necessary to have biological control with the application of an antagonistic agent, namely the provision of endophytic fungi from dayak onion flowers. This study aims to determine the types of endophytic fungi in dayak onion flowers and to determine the potential of endophytic fungi in suppressing the growth of R. solanacearum. This research was conducted from February to May 2020, taking samples of dayak onion flowers in the Experimental Field of the Faculty of Agriculture and samples of symptomatic tomato plants on the Karang Anyar Farmer Group's land then continued with isolation, purification, identification, and antagonistic testing at the Production Laboratory of the Faculty of Agriculture, Lambung Mangkurat University, Banjarbaru. The method used in this study was a one-factor completely randomized design (CRD) with nine treatments, namely C1 = endophytic fungi A + R. solanacearum, C2 = endophytic fungi B + R. solanacearum, C3 = endophytic fungi F + R. solanacearum, C4 = endophytic fungi G + R. solanacearum, C5 = endophytic fungi I + R. solanacearum, C6 = endophytic fungi J + R. solanacearum, C7 = endophytic fungi K + R. solanacearum, C8 = fungi endophytic N + R. solanacearum, and C9 = endophytic fungi P + R. solanacearum and repeated three times. This study used a comparison, namely control with three replications, in order to obtain 30 experimental units. The results of this study that endophytic fungi from dayak onion flowers have the potential to suppress the growth of R. solanacearum. Based on the research, there were 17 endophytic fungi from dayak onion flowers with nine endophytic fungi which had the fastest growth rate of radius. Fungi with the genus Colletotrichum sp., Mucor sp., and Papulaspora sp. has the potential to suppress the growth of R. solanacearum with moderate to strong percentage of inhibition.

Foraging bees of the onion (Allium cepa L.) and their impact on seed production in Tizi-Ouzou area (Algeria)

Foraging insects of Allium cepa L. (Liliaceae) have been studied during two flowering periods in 2016 and 2017, in the region of Tizi Ouzou (northeastern Algeria). At first, our observations showed that the majority of forager insects, which led and gave preference for their foraging activity of this plant, is Hymenoptera Apoidea. However, we noted also that the Apidae, Apis mellifera and the Halictidae, Lasioglossum malachurum, and L. pauxillum are the most frequent visitors on onion flowers. We highlighted all these species perform positive foraging regardless of the product harvested. Moreover, as for food research, our study described a specific behavior of honey bee, which devotes its visits to the exclusive harvesting of nectar whereas the visits of two other species are much more devoted to the mixed collection. According to other studies about Allium cepa L. (Liliaceae), we confirm the presence of pollinating insects greatly contributes to the improvement of production; indeed the grain yield obtained by cross-pollination is higher than obtained by autogamy. We gathered data showing the average weight of seeds obtained per free quadrates is 4.14 g and that of caged quadrates is 0.09 g.

POLLINATORS ACTIVITY ON ONION FLOWERS AND ITS EFFECT ON SEEDS YIELD AT SOHAG GOVERNORATE, EGYPT

The present investigations were carried out at Shandaweel Agricultural Research Station, Sohag Governorate, Egypt during 2015/2016 and 2016/2017 seasons to survey onion pollinators, study the population dynamic of the dominant pollinators during the flowering season and their diurnal activity. Also, to make a comparison between seed yield of caged and uncaged (open-pollinated) plants. Data revealed that onion flowers were visited by 21 species of insects belong to 14 families and 7 orders. Of all species 16 species were identified and 5 were not identified 2 species belong to Sarcophaga genus and 3 belong to Syrphus genus. Order Diptera was most abundant 30% followed by Hymenoptera 21%, Lepidoptera, Coleoptera 14%, and 7% for Hemiptera, Neuroptera and Thysanoptera. Of all the insect visitors, Apis mellifera L., Musca domestica (Macq.), Lucilia illustris Meigen and Syrphus spp. were the most abundant visitors. The pollinators were detected during the last week of March till the last week of April. The populations of A. mellifera and M. domestica gave the highest and significant values followed by L. illustris and Syrphus spp. The activity of these pollinators increased gradually at morning and reaches its peak at 12:00 h., with averages of 4.58, 4.39, 4.00 and 2.21 pollinators/25 plants /min. / plant, respectively in the first, and 3.52, 4.18, 3.09 and 2.33 pollinators/25 plants /min. / plant, respectively in the second season. Also, the yield of seeds from plants covered and isolated from insects decreased significantly with an averages of (45.40 and 47.60 seeds/ 20 umbels),whereas open-pollinated plants produced (711.60 and 721.10 seeds/ 20 umbels) at 2015/2016 and 2016/2017 seasons respectively.

Effects of Some Insecticides on Foraging honeybees on Onion Flowers under Field Condition

In Ethiopia onion is an important condiment, vegetable and cash crop. Various insects attack the onion in fields, and is a major threat to onion cultivation. To overcome insect infestation problem, the use of different insecticides is a major controlling mechanism. However, the uses of these insecticides against insect pests have dangerous effects on beneficial insects like honeybees (Apis mellifera L.). In this investigation, we report insecticides effects on honeybees that forage on onion flower under field condition. Bombay red onion variety was used to assess the side-effects of profenofos 750 EC, lambda-cyhalothrin 5 EC, deltamethrin 2.5 EC, diazinon 60 EC, malathion 50 EC and endosulfan 35 EC at recommended rate on honeybees foraging on onion flowers. All the tested insecticides were found to be toxic to honeybees and caused mortality within 6 h after spraying.

Effects of some insecticidal chemicals under laboratory condition on honeybees [Apis mellifera L. (Hymenoptera: Apidae)] that forage on onion flowers

In Ethiopia, Apis mellifera L. are the most important honeybees to produce diverse bee products. In addition, bees also improve crop yields through their active and efficient pollination. However, they have been killed due to the misuse of various insecticides. For this reason this study was proposed to determine in the laboratory the level of toxicity of some insecticides used widely on honeybees foraging on onion flowers. Adult A. mellifera bandasii honeybees 21 to 24 days old were collected at the Adami Tullu Agricultural Research Center (ATARC) apiary. Easy to clean and well-ventilated 15 x 10 x 15 cm cages were used for feeding, contact and fumigation tests. Six insecticides: deltamethrin 2.5 EC, diazinon 60 EC, endosulfan 35 EC, lambda-cyhalothrin 5 EC, malathion 50 EC and profenofos 750 EC, were evaluated in the laboratory at the rates suggested for onion field spraying. Each treatment was replicated three times and arranged in a completely randomized design. All of the insecticides in the contact and feeding tests were toxic to honeybees and caused mortality within a few hours after exposure. In the fumigation test, profenofos did not cause honeybee mortality until the third hour, but the remaining insecticides caused varying mortality within 24 h. Key words: Insecticides, toxicity, honeybee, bee products and crop yields.

A nanostructured copper telluride thin film grown at room temperature by an electrodeposition method

Copper telluride onion flower like microstructures, constructed by quantum dots with various diameters, were obtained by a potentiostatic electrodeposition method at room temperature. The structural, optical, surface morphology, compositional analysis and Raman spectra properties of the deposited films have been studied using X-ray diffraction, optical absorption with scanning electron microscopy, EDAX, and Raman spectroscopy. The electrolyte concentration and deposition time can be used to control the diameter of the electrodeposited quantum dots to within a range of 50–55 nm. The films are found to be stoichiometric in composition. The optical constants such as the optical band gap energy and the optical absorption spectra show significant variation in their values with a change in deposition time. Upon deposition time the band gap energy increased from a value of 2.74 to 2.89 eV.

The expression of pectin methylesterase in onion flower buds is associated with the dominant male‐fertility restoration allele

With 6 figures and 2 tablesAbstractIn this study, we investigated differential gene expression in the flower buds of male‐fertile and male‐sterile pools by using the cDNA‐sequence‐related amplified polymorphism (SRAP) method and discovered a fragment that was specifically expressed in male‐fertile pool. Cloning and sequence analysis revealed that this differentially expressed sequence corresponded to a pectin methylesterase gene in Allium cepa (AcPME). This sequence was deposited in GenBank (GU384209). In male‐fertility‐restored line, AcPME was specifically expressed in tiny buds but not in roots, leaves and bulbs. In male‐sterile line and maintainer line, AcPME was not expressed in roots, leaves, bulbs or tiny buds. AcPME was differentially expressed during different flowering stages (I, II, III, IV and V). We developed a PCR‐based marker (WHR240) associated with the expression of AcPME. This marker was validated in six other onion lines; in each case, the male‐fertility‐restored onion was reliably identified. WHR240 therefore permits the efficient marker‐assisted selection of maintainer individuals in onion breeding programmes.

Low hybrid onion seed yields relate to honey bee visits and insecticide use

Onion thrips, previously considered of minor importance to hybrid onion seed production in California, vector the newly introduced iris yellow spot virus, a serious pathogen of onions that can cause significant yield losses. Insecticide use to control onion thrips has increased in onion seed fields, coincident with a steep decrease in yields, especially in Colusa County. We examined a number of possible contributing factors and found a strong positive correlation between honey bee activity and onion seed set, indicating that a lack of pollination may be contributing to the reduced yields. In addition, honey bee visits to onion flowers were negatively correlated with the number of insecticides applied per field and field size. Reduced onion seed yields in recent years could be associated with the increase in insecticide use, which may be repelling or killing honey bees, important pollinators of this crop.

Foraging behaviour of Apis florea F., an important pollinator of Allium cepa L.

SummaryThe foraging behaviour of insect visitors to onion (Allium cepa L.) flowers was studied in relation to five environmental variables. The dwarf honey bee Apis florea L. was the most abundant flower visitor, and comprised more than 94% of the total visitors. Commencement of flight activity occurred when a minimum threshold of environmental variables was exceeded, while the cessation was governed mainly by decline in light intensity and radiation. The foraging population correlated significantly and positively with air temperature, light intensity, solar radiation and nectar-sugar concentration and negatively with relative humidity. Path coefficient analysis, revealed, however, that the direct effect of temperature was large and positive followed by light intensity and solar radiation while the direct effect of relative humidity was small and negative. The direct effect of nectar-sugar concentration was positive and negligible. Path coefficient analysis thus gave a clearer picture of the effects than did a simple correlation analysis. On average A. florea visited 1.33±0.26 and 6.17±0.58 umbels and flowers/min, during different hours of the day. The insect pollinated plots produced significantly more seeds with heavier weights than those isolated from insect visits.