Mg Of Sugars Research Articles

Comparative nectar dynamics in four ornithophilous Melocactus (Cactaceae) species in a seasonally dry tropical forest

AbstractNectar is an important floral resource, often representing the only source of water for pollinators in arid environments. We investigated whether successive nectar removal would affect the nectar production dynamics of four Melocactus species growing in the Caatinga domain. Nectar was serially extracted from flowers four times per day at regular 60‐min intervals after anthesis. The cactus species showed a consistent pattern of secretion linked to ornithophily, with no significant responses to successive nectar removal and no reabsorption. Nectar secretion covered the entire period of anthesis, starting at 2:30 p.m. and continuing to 5:30 p.m., with the production of 11–38 μl per flower, with sugar concentrations of 10%–32% (3–16 mg of sugar). Individual flowers produced average amounts of 16.9–3.43 mg of sugar per day, corresponding to energy values of 0.06–0.28 kJ. Sympatric populations produced an average of 150–200 flowers per day. The nectar produced by Melocactus can therefore meet the daily energy needs of hummingbirds, which is of special importance during the dry season, when resources are scarce in the Caatinga.

The Impact of Fire on Nectar Quality and Quantity for Insect Pollinator Communities

Grassland insect pollinators have undergone population declines due to habitat loss and degradation. Patch-burning is a management method used to reduce woody plant encroachment and maintain grassland habitats. However, the impacts of fire on the quality and quantity of floral resources (nectar volume, total sugar, and sucrose concentration) available to insect pollinators are understudied. Evaluating how time since last fire and season of fire impact nectar quality and quantity is vital to understanding the overall impact of fire on insect pollinator communities. For this study, 10 flowering forb species (Asclepias viridis, Baptisia alba, Cirsium undulatum, Desmodium canadense, Monarda citriodora, Monarda fistulosa, Oenothera speciosa, Penstemon tubaeflorus, Ruellia humilis, Spiranthes cernua) were selected in The Nature Conservancy's Joseph H. William's Tallgrass Prairie Preserve in an area managed with patch-burning and cattle grazing. Study sites were burned in spring 2018, summer 2018, summer 2019, and spring 2020, with three replicates of each treatment (for 12 total burn units). In each unit, we collected nectar from flowering individuals of each plant species with microcapillary tubes to measure standing crop or the nectar in flowers at any given time that is available to insect pollinators. Total volume of nectar and sucrose concentration were recorded, and total mg of sugar was calculated. Desmodium canadense flowering individuals were only located in units burned the previous spring, whereas P. tubaeflorus flowering individuals were only located in units burned the previous summer. For the eight remaining species, total volume of nectar, total mg of sugar, and sucrose concentration varied with different burn regimens for different species. Cirsium undulatum inflorescences with crab spiders (Thomisidae) had higher volumes of nectar and higher amounts of sugar available. This study highlights how a patch-burn approach with different fire return intervals may benefit insect pollinators at the community level by providing a wide range of nectar qualities and quantities to support insect pollinators with different nutritional needs.

EFFECTIVENESS OF COCONUT WATER CONSUMPTION ON BLOOD PRESSURE

Blood pressure as a circulatory system is influenced by psychosocial (stress), genetic, age, sex, nutritional status, and lifestyle (diet, lack of fiber consumption, smoking, lack of physical activity). 30 ml of young coconut water containing 61 mg of potassium, 5.45 mg of sodium, and 1.3 mg of sugar can affect changes in blood pressure. This study aims to determine the effect of consumption of young coconut water on blood pressure nursing students at Respati University Yogyakarta. This type of research is a quasi-experiment with the design of a pre and post-test nonequivalent control group. The sampling technique used simple random sampling, as many as 36 samples. Test using T-test Paired and Wilcoxon. The results of the analysis of systolic and diastolic blood pressure pretest-posttest in the control group obtained p-value of 0.121 and 0.361. The systolic blood pressure analysis and diastole pre-post test results in the experimental group obtained p-values ​​of 0.030 and 0.194. The posttest systolic and diastolic blood pressure analysis in the control and experimental groups obtained p-values ​​of 0.021 and 0.371, which concluded that there was an effect of consumption of coconut water on systolic blood pressure in nursing students.
 Keywords: Blood Pressure; Diastolic; Systolic; Young Coconut Water

The Effectiveness of Young Coconut Water and Watermelon Juice in Reducing Blood Pressure

Background: Blood pressure is influenced by psychosocial (stress), genetic, age, gender, nutritional status, and lifestyle (diet, lack of fiber consumption, smoking, lack of physical activity). 30 ml of young coconut water contains 61 mg of potassium, 5.45 mg of sodium, and 1.3 mg of sugar, affecting blood pressure changes. Coconut water contains K minerals and is useful for lowering blood pressure. Whereaswatermelon contains anti-hypertensive content, namely sodium, beta carotene, and potassium. Watermelon is rich in water, amino acids, L-arginine, which can maintain healthy blood pressure. Aim: This study aims to determine the effect of young coconut water and watermelon juice on blood pressure in the 2013 nursing students of Respati University Yogyakarta. Methods: This type of research is a quasi-experimental design with a nonequivalent control group pre and post-test. The sample was taken by simple random sampling, namely the control group (18 respondents), the young coconut water group (18 respondents), and papaya juice (18 respondents). Data pre-posttest of each group was tested using Paired T-test. The comparison control-treatment group was tested using an independent-test. Results: The mean differences of systole and diastole pre-posttest blood pressure in the control group were -1.8 mmHg and -1.0 mmHg. The mean difference in systole blood pressure and the pre-posttest diastole of young coconut water groups were -3.1mmHg and -2.4 mmHg. The mean systole and diastole blood pressure in the pre-posttest watermelon juice group were -2.9 mmHg and -1.5 mmHg. The pre-posttest results of systole and diastole blood pressure analysis in the p-value control group were 0.100 and 0.450. The pre-post test results of systole and diastole blood pressure analysis of young coconut water groups gained p-value of 0.030 and 0.194. The pre-post test results of the juice watermelon group's systole and diastole blood pressure analysis gained p-value of 0.032 and 0.181. The posttest results of systole and diastole blood pressure analysis in the control group and young coconut water gained p-value of 0.014 and 0.157. The post-test results of the systole and diastole blood pressure analysis control group and juice watermelon gained p-value of 0.013 and 0.420. Conclusion: Consumption of young coconut water and watermelon juice affects systole blood pressure, but it does not affect diastole blood pressure in nursing students in 2013 in Respati University Yogyakarta. Keyword: Blood pressure, Coconut Water, Watermelon Juice

Nectar secretion and pollen production in Hyacinthus orientalis ‘Sky Jacket’ (Asparagaceae)

Flowering, nectar secretion, and pollen production in <em>Hyacinthus orientalis</em> ‘Sky Jacket’ (Asparagaceae) were studied between 2013 and 2015 in Lublin, SE Poland (51°16' N, 22°30' E). The flowering was weather-dependent. It started at the beginning of April or at the end of the month and lasted 14–24 days. The mass of nectar, sugar concentration in the nectar, nectar sugar mass, anther size, and pollen mass in flowers all depended on the flower position in the inflorescence and differed significantly between the years of study. The greatest mass of sugars and pollen was recorded in low-positioned flowers. On average, <em>H. orientalis</em> ‘Sky Jacket’ produced 1.63 mg of sugars and 3.51 mg of pollen per flower. The floral reward was attractive for <em>Apis mellifera</em> and <em>Bombus</em> spp., which indicate that the species should be propagated not only for its decorative value but also for supporting pollinators in early spring.

Patterns of Nectar Production in <i>Asclepias curassavica</i> (Apocynaceae))

Milkweeds are important nectar resources for insects in the New World. In addition, nectar is the germination medium for milkweed pollen. This study is the first controlled, greenhouse examination of patterns of nectar production in a milkweed species. We measured nectar volume, concentration, and mg of sugar in the pantropical, weedy milkweed Asclepias curassavica. Our results show that A. curassavica secretes nectar primarily during daylight hours and it continues at a constant daily rate for four to five days. Freshly secreted nectar is lower in sugar concentration than older nectar. This provides an opportunity for milkweed pollen to germinate throughout the day, but pollen germination could be inhibited at times when the sugar concentration increases. Nectar production in A. curassavica is adapted to attract diurnal insect pollinators over several days and to allow pollen germination to occur quickly. Significant differences in nectar production exist among plants and among inflorescences within plants. Nectar production increases in flowers when nectar is extracted using paper wicks that simulate removal by insects in nature. Removal-enhanced nectar production in milkweeds may allow plants to adjust resources to inflorescences receiving insect visitation. Significant inter-plant differences in nectar production and the unique milkweed flower provides a model system for examining the role of pollinator-mediated selection on nectar traits.

Nectar and pollen production in ornamental cultivars of Prunus serrulata (Rosaceae)

Abstract Planting ornamental species can help to create pollinator-friendly habitats. In the present study the flowering phenology and floral reward (nectar and pollen) in two cultivars of Prunus serrulata (‘Kanzan’ and ‘Amanogawa’) were evaluated in 2014-2015 in the city of Lublin (south-east Poland). On average, the onset of flowering of P. serrulata occurred in the first ten days of April (‘Kanzan’) or at the end of April (‘Amanogawa’), and lasted 8-17 days. In each year of the study, P. serrulata ‘Kanzan’ started flowering 11-18 days earlier than P. serrulata ‘Amanogawa’. The double flowers of P. serrulata ‘Kanzan’ offered only tiny amounts of nectar and pollen. The total mass of sugars was 0.59 mg per flower and that of pollen 0.08 mg per flower. The semi-double flowers of P. serrulata ‘Amanogawa’ produced 4.5 mg of sugars per flower and 0.17 mg of pollen per flower. The frequency of pollinator visits to flowers was low in P. serrulata ‘Amanogawa’ and very low in P. serrulata ‘Kanzan’. Therefore, if pollinator-friendly arrangements are made in urban areas, these cultivars should not be planted.

Impact of zoophytophagy on chemical content of Podisus nigrispinus (Hemiptera: Pentatomidae) fed on lepidopteran larvae and cotton leaves

Zoophytophagy is an important factor in the colonization and successful establishment of the generalist predator Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae) in cotton crops. Here, we evaluated the nutritional state (carbohydrates, lipids and proteins and body weight) of P. nigrispinus nymphs fed on: i) Alabama argillacea (Hubner) (Lepidoptera: Noctuidae) larvae with cotton leaves, ii) A. argillacea larvae, or iii) Tenebrio molitor L. (Coleoptera: Tenebrionidae) larvae. The body weight and chemical composition of preys and cotton leaves were also quantified. Podisus nigrispinus nymphs had similar levels of proteins and carbohydrates when they fed on A. argillacea or T. molitor. However, P. nigrispinus nymphs fed on A. argillacea larvae and cotton leaves had higher levels of proteins, sugars and glycogen content than those fed only on preys. Cotton leaves had 7.11 mg of protein and 13.71 mg of sugars. Therefore, feeding on cotton leaves increases the nutritional state of the zoophytophagous predator P. nigrispinus, which can enhance its survival in periods of prey scarcity.

ALKALI PRE-TREATMENT AND ENZYMATIC HYDROLYSIS OF Arundo donax FOR SINGLE CELL OIL PRODUCTION

Microbial oil obtainable from the fermentation of lignocellulose hydrolysates represents a promising and sustainable alternative to first generation biodiesel. Among the lignocellulosic crops, giant reed (Arundo donax) is attracting interest due to the impressive biomass yield and the low input requirement. However, a delignification step is needed to facilitate the fermentable sugar release from the lignocellulosic matrix, paying attention to the production of growth inhibitors that represent a bottleneck in the development of microbial oil production. The aim of this study was to evaluate the suitability of an enzymatic hydrolysate of alkali pre-treated A. donax biomass, as a substrate for the growth of the oleaginous yeast Lipomyces starkeyi. Specific attention was also paid to possible inhibitory effects of compounds generated by the alkaline pre-treatment (10% slurry, NaOH 0-1.5% w/w, 120 C, 20 min). Increasing NaOH levels enhanced the release of phenolic compounds and increased the fermentable sugar yield after enzymatic hydrolysis of the washed pre-treated fiber. Saccharification yields reached a plateau in correspondence to NaOH 1.2% dose, which gave 407 mg of sugars per g of dry biomass. A medium containing 30 g/L of reducing sugars from the hydrolysate resulted suitable for the growth of L. starkeyi and for lipid accumulation, achieving 12.2 g/L of dry cell biomass with 43% w/w of total lipids. The pre-treatment produced soluble inhibitors that affected moderately the yeast growth in an initial phase, followed by a recovery. Thus, extensive washing of the fiber could be avoided, while a thorough filtration after the pre-treatment would be recommended.

Measurement of protein and sugar consumed by bumblebee larvae under standard and food stress conditions using lanthanide complexes

Measurement of food consumed by larvae of progressive provisioning bees requires an experimental approach that marks the food sources appropriately. This paper aims to measure the amount of sugars and proteins consumed by a single bumblebee larva and to define, how the proportion between protein and sugar changes under stress conditions. We marked sugar and pollen sources using lanthanide (gadolinium, dysprosium) complexes with diethylene-triamine-pentaacetic acid (DTPA) chelator. We precisely quantified the amount of Gd and Dy in feces, and thus quantified linearly correlated protein and sugar consumed by males and females (workers) of Bombus terrestris during their development. We compared body mass, total amount of ingested sugar and total amount of ingested protein in colonies which are fed ad libitum and in colonies with restricted feeding. Males fed ad libitum during their development ingested 0.52 mg of protein and 4.43 mg of sugar, and workers fed ad libitum ingested 0.54 mg of protein and 4.26 mg of sugar per 1 mg of dry body weight on average. Food-stressed workers ingested 0.51 mg of protein and 4.65 mg of sugar per 1 mg of dry body weight on average. Strong positive correlation between body mass, total protein ingested, and total sugar ingested in all our experiments was present. However, the consumption of sugar grew steeper with the consumption of protein in colonies under food stress compared to the ad libitum-fed colonies. In conclusion, we show the existence of different patterns in ingestion of protein and sugar between well-fed and food-stressed bumblebee colonies.

Morphology and some aspects of reproductive biology of perennial buckwheat <i>Fagopyrum cymosum</i> Meissn. in the Republic of Tatarstan

Fagopyrum cymosum Meissn. is a wild perennial species of buckwheat, which grows in southwest Asia. Despite rather active economic use of perennial buckwheat, only the most general information concerning the morphology and reproductive biology of the species is found in the literature. At the same time, such information could be useful for conducting genetic-selection works. In the case of the introduction of F. cymosum into the territory of European Russia, a comprehensive study of a new species will be required. The purpose of this study is a complete morphological description, identification of flowering and nectar features, evaluation of pollen fertility and seed productivity of perennial buckwheat F. cymosum in the Republic of Tatarstan. As a result of the studies, a morphological characteristic of perennial buckwheat is given. The strong branching of shoots and flower-bearing axes of F. cymosum was revealed. It turned out that the structure of the buckwheat flower is characterized by high variability. Flowers with the highest frequency were found with the formula P₅A₈G₍₃₎ (83,3%) and P₅A₉G₍₃₎ (10,7%). Among the anomalous flowers, variants with a variable number of stamens were most often encountered. Perennial buckwheat in the Republic of Tatarstan was pollinated by wild Hymenoptera and Diptera. The sugariness of perennial buckwheat nectar compared to the selection varieties of buckwheat was insignificant, averaged 0,03 mg of sugar per flower. The fertility of pollen fluctuated within 87,596,8%, depending on the weather conditions. The real seed productivity of perennial buckwheat varied from 26,7 to 186,0 seeds per plant. As a result of the study the authors have concluded that perennial buckwheat can be grown in the conditions of the Middle Volga Region as an annual crop.

Conversion of Symphytum officinale and Panicum virgatum plant extracts to 5-hydroxymethylfurfural catalysed by metal chlorides in ionic liquids

The present work examined the potential for two plants grown on Canadian soil, Symphytum officinale L. (common comfrey) and Panicum virgatum L. (switchgrass), to produce 5-hydroxymethylfurfural using metal chloride catalysis in two ionic liquids, 1-butyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium chloride. Furthermore, two pre-treatments, namely the dilute sulfuric acid treatment and the methanol extraction, were studied as a way to improve sugar availability and increase 5-hydroxymethylfurfural yields compared with untreated biomass. The 0.5 mol/L H2SO4 hydrolysis under autoclave conditions produced sugar-rich extracts containing 230 ± 23 mg of sugars per gram of hydrolysed biomass for comfrey and 425 ± 13 mg of sugars per gram of hydrolysed biomass for switchgrass. The methanol extraction produced extracts high in simple sugars with concentration of 300 ± 60 mg of sugars per gram of dry extract for comfrey and 202 ± 16 mg of sugars per gram of dry extract for switchgrass. The yield of 5-hydroxymethylfurfural was improved from less than 1% using untreated biomass to 6.04% and 18.0% using dry methanol extracts of comfrey and switchgrass, respectively. These yields, although small, are important, as they show for the first time that a methanol extract could enhance the metal chloride catalysis in ionic liquids for 5-hydroxymethylfurfural production from biomass.

Pollination partial recovery across monospecific plantations of a native tree (Inga vera, Leguminosae) in the Atlantic forest: Lessons for restoration

In the last decades several approaches have been adopted for tropical assisted forest restoration from monospecific plantations to the establishment of highly-diverse tree stands. However, the long-term viability of restored forest and their capacity to provide the required services demand continuous evaluation to guide future initiatives. We aimed to evaluate the existence of pollination recovery in monospecific tree plantations in a hyper fragmented landscape of the Atlantic forest in northeast Brazil. By using Inga vera as a model species, we compared several relevant aspects relative to tree reproduction such as reproductive phenology, floral structures, nectar consumption, fruit- and seed-set, between monospecific plantations and native conspecific populations. Populations of I. vera from both native forest stands and planted areas flowered in overlapping periods in the dry season, while fruiting occurred at the beginning of the rainy season. Flowers of planted populations were significantly larger (11% in the size of the calyx, corolla and androecium – staminal tube and filaments) relative to natural populations. Flowers of both planted and natural populations secrete ca. 46 μl of nectar with concentration of 20.2% and 45.8 mg of sugars throughout the anthesis. However, the average volume of nectar consumed by visitors per flower in planted populations was 30% lower than in natural populations. The frequency of pistils with pollen tubes and the average number of seeds per fruit were similar between natural and planted populations. Nevertheless, surprisingly, the natural fruit set was 49% lower in planted relative to natural populations. Lower consumption of nectar and natural fruit set in planted populations of I. vera, in relation to the natural populations, indicate a partial recovery of the pollination process through the practice of planting single species of a tree in clusters of individuals. Our results add some doubts about the long-term viability and the ability of monospecific plantations in delivering services such as increased pollination capacity in human-modified landscapes.

Flowering and Nectar Secretion in two Forms of the Moldavian Dragonhead (Dracocephalum moldavica L.) – A Plant with Extraordinary Apicultural Potential

Abstract Dracocephalum moldavica is a valuable reward plant for flower visitors. The aim of the study was to ecologically characterise its flowers and leaves and assess the seasonal and daily dynamics of flowering in two white- and blue-flowered forms of this species in 2004 and 2005. Additionally, the duration and abundance of plant flowering as well as the nectar amount and sugar content were analysed. The signalling attractants of the plant include an intense scent emitted by trichomes located not only on its flowers but also on its stem and leaf surfaces. The average corolla length is 24 mm and the corolla tube, which can be completely filled with nectar, is 8.6 mm long. The floral lifespan was shown to reach 2-3 days and the mean blooming duration of both forms of dragonhead 45-48 days. The white-flowered plants produced a substantially greater number of flowers (5352) than the blue-flowered form (2965). The nectar amount obtained from ten blue flowers was 15.33 mg and that extracted from white flowers reached 17.56 mg, with 49.4% and 51.5% content of sugar, respectively. The total sugar mass produced by one white-flowered plant was 4656 mg, while one blue-flowered plant yielded 2164 mg of sugars. The sugar yield calculated in the study for the white-flowered form (586 kg · ha−1) was two-fold higher than that in the blue-flowered plants.

Energy Drinks: What Teenagers (and Their Doctors) Should Know

1. Kwabena L. Blankson, MD* 2. Amy M. Thompson, DO† 3. Dale M. Ahrendt, MD‡ 4. Vijayalakshmy Patrick, MD§ 1. *Maj, US Air Force, Adolescent Medicine, Naval Medical Center, Portsmouth, VA. 2. †Maj, US Army, Adolescent Medicine Fellow, San Antonio Uniformed Services Health Education Consortium (SAUSHEC), San Antonio, TX. 3. ‡Lt Col, US Air Force, Program Director, Adolescent Medicine, Fellowship, SAUSHEC, San Antonio, TX. 4. §Psychiatrist, Brooke Army Medical Center Associate Professor, University of Texas Health Science Center, San Antonio, TX. Hundreds of different energy drinks are available and are marketed to adolescents, carrying the potential for substance abuse that involves caffeine and alcohol. Clinicians must be educated to deal with their patients’ use of these products. After reading this article, readers should be able to: 1. Understand the size and scope of the energy drink market and recognize common energy drink brands. 2. Know that adolescents are high consumers of energy drinks and use them as performance enhancers. 3. Know the contents of energy drinks and their adverse effects and safety concerns. 4. Know that energy drinks can be a cause of tachycardia, hypertension, obesity, and other medical problems in adolescents. 5. Know the dangers of mixing energy drinks with alcohol. 6. Understand the relationship between caffeine tolerance/dependence and alcohol tolerance/dependence. 7. Understand the importance of screening teenagers for energy drink use in the office setting and offering appropriate counseling. Energy drinks are caffeinated beverages advertised as boosting the immune system, enhancing performance, and creating a “buzz” or a “high.” Some of these drinks contain alcohol, and sometimes consumers mix them with alcoholic beverages. This article reviews current information about the content, benefits, and risks of the use of these energy drinks by adolescents. Adolescents are no strangers to energy drinks, and over the past 2 years, media reports have heightened the awareness of doctors, parents, and lawmakers. In 2010, nine university students in Washington State were hospitalized and one almost died; their illness was attributed to a fruit-flavored, caffeinated alcoholic drink. A month earlier, on a college campus in New Jersey, 23 students were hospitalized after becoming intoxicated, again reportedly after drinking the same …

Pollination ecology of Melaleuca cajuputi, Nypa fruticans and their flower visitors

SummaryThe submerged Melaleuca forests have an important role in the regulation of climate and the protection of wildlife and the environment in southern Vietnam. This paper studies the pollination ecology of the Asian giant honey bee (Apis dorsata), the Asian dwarf honey bee (Apis florea) and other pollinators on the two prominent plants (Melaleuca cajuputi and Nypa fruticans) in the forests. The results show that the nectar of Melaleuca flowers was secreted in the largest volume with the lowest sugar content in the early morning. Then, due to evaporation, the volume dropped to the lowest with the highest sugar content in the early afternoon. The sugar value present in Melaleuca flowers was the highest (466 Mg of sugar per flower) at 10.00 h in the morning. Nypa flowers opened early in the morning, their pollen release increased gradually, reached a peak at 09.00 h and finished at sunset. The study of pollinators on the Melaleuca and Nypa flowers showed the three following forms of partitioning in the Melaleuca forests: 1. Different plants have different visitors; 2. Different visitors visit the same plant at different times; and 3. For a visitor species, time is partitioned to visit different plants.

Effect of 2,4-d, glutamine and BAP on embryogenic suspension culture of date palm (Phoenix dactylifera L.)

The proliferation of embryogenic suspension culture in two cultivars (Jihel and Bousthami Noir) of Phoenix dactylifera L. was tested on liquid media with or without 2,4-d and with different glutamine concentrations (3.35 × 10−4, 6.7 × 10−4 and 13.4 × 10−4 M). The liquid medium with 0.1 mg l−1 2,4-d and 6.7 × 10−4 M glutamine has clearly improved the proliferation of somatic embryos. In fact, when glutamine concentration increased from 3.35 × 10−4 to 6.7 × 10−4 M, the yield of somatic embryos increased from 14 to 56 embryos per 100 ml of culture medium for “Jihel” cultivar and 25–71 embryos per 100 ml of culture medium for “Bousthami Noir” cultivar. In contrast, increasing glutamine concentration from 6.7 × 10−4 to 13.4 × 10−4 M, the embryos yield was negligible. Based on biochemical analysis, the highest accumulation of proteins and sugars was obtained in liquid medium with 0.1 mg l−1 2,4-d and 6.7 × 10−4 M glutamine (118 and 91 mg of proteins g−1 DW, respectively, for “Jihel” and “Bousthami Noir” cultivars; 194 mg of sugars g−1 DW for “Jihel” cultivar and 182 mg of sugars g−1 DW for “Bousthami Noir” cultivar). In addition, the supply of 0.05 mg l−1 BAP on the germination medium could be useful in terms of germination percentage of somatic embryos. When BAP concentration increased from 0.05 to 0.2 mg l−1, the germination percentage of somatic embryos decreased from 14.2 to 4.9%, while secondary embryogenesis increased from 26.4 to 45.2%.

Floral nectaries and nectar production in brown mustard (Brassica juncea) and white mustard (Sinapis alba) (Brassicaceae)

The dynamics and abundance of nectar secretion as well as sugar productivity were studied in flowers of brown mustard (Brassica juncea) cv. Malopolska and white mustard (Sinapis alba) cv. Borowska. Moreover, floral nectaries were examined under LM and SEM. In both cultivars lateral and median pairs of nectaries secreted nectar. However, differences were found in morphology and activity of these pairs. The lateral nectaries produced more nectar than the median ones. Nectar secretion started at loose bud and peaked during anther dehiscence. Average amount of nectarsecreted by 100 flowers of cv. Malopolska and cv. Borowska were 119.9 mg and 134 mg. Mean concentration of nectar was 26.7% and 23.4%, respectively. One hundred flowers of cv. Malopolska and cv. Borowska secreted 28.4 mg and 24.9 mg of sugars in nectar. Estimated sugar productivity per 1 ha of crop was 65.5 kg and 71.2 kg, respectively.

Patterns and implications of floral nectar secretion, chemical composition, removal effects and standing crop in Mandevilla pentlandiana (Apocynaceae)

Abstract Flower morphology, nectar features (chemical composition, production pattern, removal effects, and standing crop) and floral visitors are analysed in an Argentine population of Mandevilla pentlandiana . Nectar variability was examined during the lifetime of a single flower, over the course of the flowering season, and at different times of the day. Nectar is sucrose dominant. There were some variations in the proportions of sugar throughout both the flower lifespan and the flowering season. Flowers produced most nectar during bud-stage. Nectar secretion ceased near the end of the first day after flower opening. Nectar quantity varied as a function of flower age due to a combination of nectar secretion, cessation, and resorption periods. Overall sugar production was increased by nectar removal. Standing crop data showed that each open flower and inflorescence offers c . 2 and 11 mg of sugar respectively at any time of the flowering season. There was higher nectar availability at the beginning of the flowering season compared with the rest of the period. Flowers were visited by bumblebees, honeybees and hummingbirds. The greater the number of open flowers and the nectar variance, the more the mean reward quantity per flower available in the inflorescence. The sources of nectar variability in M. pentlandiana seem to be linked with both the female function (nectar resorption, nectar cessation) and the male one (early and comparatively large nectar availability, variation in nectar production as the flower ages, nectar secretion stimulation by nectar removals).

Patterns and implications of floral nectar secretion, chemical composition, removal effects and standing crop inMandevilla pentlandiana(Apocynaceae)

Flower morphology, nectar features (chemical composition, production pattern, removal effects, and standing crop) and floral visitors are analysed in an Argentine population ofMandevilla pentlandiana. Nectar variability was examined during the lifetime of a single flower, over the course of the flowering season, and at different times of the day. Nectar is sucrose dominant. There were some variations in the proportions of sugar throughout both the flower lifespan and the flowering season. Flowers produced most nectar during bud-stage. Nectar secretion ceased near the end of the first day after flower opening. Nectar quantity varied as a function of flower age due to a combination of nectar secretion, cessation, and resorption periods. Overall sugar production was increased by nectar removal. Standing crop data showed that each open flower and inflorescence offersc. 2 and 11 mg of sugar respectively at any time of the flowering season. There was higher nectar availability at the beginning of the flowering season compared with the rest of the period. Flowers were visited by bumblebees, honeybees and hummingbirds. The greater the number of open flowers and the nectar variance, the more the mean reward quantity per flower available in the inflorescence. The sources of nectar variability inM. pentlandianaseem to be linked with both the female function (nectar resorption, nectar cessation) and the male one (early and comparatively large nectar availability, variation in nectar production as the flower ages, nectar secretion stimulation by nectar removals).