Topology of thermogenic tissues of Alocasia macrorrhizos (Araceae) inflorescences

Botany ◽  
2009 ◽  
Vol 87 (12) ◽  
pp. 1232-1241 ◽  
Author(s):  
Anton Ivancic ◽  
Olivier Roupsard ◽  
José Quero-García ◽  
Metka Sisko ◽  
Andreja Urbanek Krajnc ◽  
...  
Keyword(s):  
Ambient Air ◽  
Early Morning ◽  
Main Peak ◽  
Female Part ◽  
Female Phase ◽  
Male Phase ◽  
Male Part ◽  
Fertile Male

Thermogenesis and heat generating tissues in inflorescences of the giant taro ( Alocasia macrorrhizos (L.) G. Don) were studied from December 2005 to February 2006, on the Island of Espiritu Santo, Vanuatu. Temperatures were recorded in the ambient air, in the peduncle tissue, and on 12 positions within spadices during periods of maximum thermogenic activity, in the early morning hours of the female and male phases. The study showed that there were three thermogenic tissues: the sterile appendix, the fertile male part, and the differentiated sterile area below the fertile male part. During the female phase, heat was generated by the sterile appendix and the differentiated sterile area below the fertile male part, the smallest region of the spadix (mean ± SD = 0.86 ± 0.24 cm, 3.17% of the spadix length), and most probably by the fertile male part. Within the spadix, average temperatures gradually increased from the base of the female part and reached the first peak at the midpoint of the differentiated sterile area below the fertile male part (36.11 ± 1.54 °C). After that, they gradually decreased towards the midpoint of the fertile male part and increased again, reaching a second (main) peak at 1/4 of the sterile appendix height (44.83 ± 1.87 °C). From 1/4 to 1/2 of the appendix height they remained at more or less the same level, and then they decreased towards the tip of the spadix. During the male phase, heat was generated only within the fertile male part.

Thermogenic flowering of taro (Colocasia esculenta, Araceae)

2004 ◽  
Vol 82 (11) ◽  
pp. 1557-1565 ◽  
Author(s):  
Anton Ivancic ◽  
Vincent Lebot ◽  
Olivier Roupsard ◽  
José Quero Garcia ◽  
Tom Okpul
Keyword(s):  
Ambient Air ◽  
Early Morning ◽  
Colocasia Esculenta ◽  
Critical Periods ◽  
Final Phase ◽  
Inflorescence Development ◽  
Air Temperatures ◽  
Female Phase ◽  
Male Phase ◽  
The Mean

Thermogenesis and its association with taro (Colocasia esculenta (L.) Schott) flowering was studied during the warmest period of the year (December 2002 – February 2003) within a large collection of heterogeneous plant material on Espiritu Santo, Vanuatu. On each studied inflorescence, temperatures of the three main parts of the spadix and the ambient air were recorded during a period of 38 h. The investigation indicates that significant thermogenic activity of taro inflorescences takes place during two successive nights: (1) during the night when an inflorescence becomes odorous (the female phase) and (2) a night later, when microsporogenesis approaches its final phase (the male phase). The highest average difference between mean temperatures of the ambient air and inflorescences were documented during the female phase, at 0500 hours (the mean temperature of the sterile appendix was 29.1 ± 0.9 °C (P = 0.05) and this was 6.8 °C above the temperature of the ambient air). Thermogenic activity is synchronized with the protogynous nature of the species and insect pollination in the early morning hours. Its main putative functions are (1) to reduce the deviations of ambient air temperatures during the most critical periods of flowering, and (2) to promote cross-pollination. It stops 1–1.5 h after pollen has been released.Key words: taro, Colocasia esculenta, thermogenesis, inflorescence development, pollination.

Respiration and temperature patterns in thermogenic flowers of Magnolia ovata under natural conditions in Brazil

2010 ◽  
Vol 37 (9) ◽  
pp. 870 ◽  
Author(s):  
Roger S. Seymour ◽  
Ilse Silberbauer-Gottsberger ◽  
Gerhard Gottsberger
Keyword(s):  
Ambient Temperature ◽  
Respiration Rate ◽  
Energy Savings ◽  
Ambient Air ◽  
Pollination Biology ◽  
Specific Rate ◽  
Maximum Mass ◽  
Natural Conditions ◽  
Female Phase ◽  
Male Phase

The roles of floral thermogenesis in pollination biology include attraction and reward of insects. Magnolia ovata (A.St.-Hil.) Spreng. produces ~56 g, bisexual, protogynous and scented flowers. Two distinct episodes of thermogenesis occur during anthesis: one beginning at about sunset and lasting ~3 h in the female phase and another that occurs synchronously 24 h later and lasting 4 h in the male phase. Female stage flowers produce up to 0.36 W to reach 27.3°C, which is 3.9°C above ambient air. In the male stage, corresponding values are 0.79 W, 29.7°C and 5.4°C, respectively. Most heat is generated in the petals in both phases (74 and 65%). Maximum, mass-specific rate of respiration is 23 nmol s–1 g–1 in the petals and 100 nmol s–1 g–1 in the anthers. The flowers are apparently not thermoregulatory, because respiration rate decreases, rather than increases, with decreasing ambient temperature. Scarab beetles, Cyclocephala literata, enter the floral chamber created by the petals in the female phase, mate, consume floral parts (mainly petals) and then depart in the male phase. Temperatures maintained in the floral chamber are sufficient to provide beetles with significant energy savings during their activities in both phases. Thermogenesis is, therefore, consistent with volatilisation of floral fragrances and energy rewards to beetle visitors.

scholarly journals Temporal variability, sources, and sinks of C<sub>1</sub>-C<sub>5</sub> alkyl nitrates in Coastal New England

2009 ◽  
Vol 9 (6) ◽  
pp. 23371-23418 ◽  
Author(s):  
R. S. Russo ◽  
Y. Zhou ◽  
K. B. Haase ◽  
O. W. Wingenter ◽  
E. K. Frinak ◽  
...  
Keyword(s):  
New England ◽  
New Hampshire ◽  
Dry Deposition ◽  
Ambient Air ◽  
Early Morning ◽  
Secondary Source ◽  
Alkyl Nitrates ◽  
Mixing Ratios ◽  
Alkyl Nitrate ◽  
Marine Source

Abstract. Seven C1-C5 alkyl nitrates were measured both on the mainland and off the coast of New Hampshire using gas chromatographic techniques. Five separate data sets will be presented to characterize the seasonal and diurnal trends and the major sources and loss processes of these compounds. In situ measurements were conducted at the University of New Hampshire (UNH) Atmospheric Observing Station at Thompson Farm (TF) located in southeast NH during winter (January–February) and summer (June–August) 2002 and summer (July–August) 2004. The median (±standard deviation) total alkyl nitrate mixing ratio (ΣRONO2) was 25 (±7) in winter and 16 (±14) pptv in summer. Furthermore, daily canister samples collected at midday and later analyzed in the laboratory from January 2004–February 2008 gave median ΣRONO2 of 23 (±8) in winter and 14 (±10) pptv in summer. Alkyl nitrate mixing ratios increased throughout the morning and were highest in the afternoon reflecting mixing of remnant boundary layer air toward the surface and photochemical production during the day. During summers 2002 and 2004, MeONO2 decreased overnight and reached minimum hourly average mixing ratios in the early morning (05:00–07:00 LT). Comparison with wind speed and trace gas (i.e., hydrocarbons, ozone, carbon monoxide, total reactive nitrogen) trends suggested that dry deposition contributed to the early morning MeONO2 minimum which is a previously unaccounted for removal mechanism. The mean dry deposition rate and velocity of MeONO2 was estimated to be −0.5 nmol m−2 hr−1 and 0.13 cm s−1, respectively. Results from ambient air and surface seawater measurements made onboard the NOAA R/V Ronald H. Brown in the Gulf of Maine during the 2002 New England Air Quality Study and from ambient canister samples collected throughout the Great Bay estuary in August 2003 are also presented. Comparisons between the alkyl nitrate trends with anthropogenic and marine source fingerprints and tracers suggest that a marine source of alkyl nitrates is not significant in coastal New England. Given the apparent prominence of a secondary source, comparisons between observed and predicted alkyl nitrate/parent hydrocarbon ratios were made which demonstrated that background mixing ratios have a continuous and prevalent influence on the alkyl nitrate distribution.

Pollination of Amorphophallus johnsonii (Araceae) by carrion beetles (Phaeochrous amplus) in a Ghanaian rain forest

1996 ◽  
Vol 12 (3) ◽  
pp. 409-418 ◽  
Author(s):  
Daniel D. N. Beath
Keyword(s):  
Rain Forest ◽  
Rainy Season ◽  
Male Inflorescence ◽  
Large Numbers ◽  
Female Phase ◽  
Male Phase ◽  
Carrion Beetles ◽  
Main Rainy Season

ABSTRACTAmorphophallus johnsonii (N. E. Brown) flowers during April in the main rainy season in Ghana. Anthesis starts at dusk with fluid oozing from the upper spadix accompanied by a strong aminoid odour. Just after dark large numbers of carrion beetles (Phaeochrous amplus) and occasional dung fly species (Hemigymnochaeta unicolor and Paryphodes tigrinus) visit the inflorescences. The beetles become trapped in the lower spathe overnight and remain in the spadix until the following evening. Between 1630 and 1645 h the following day, the anthers produce long threads of sticky pollen. The trapped beetles escape just after dark by crawling up the spadix, past the dehisced anthers and fly away from the spadix tip. Marked beetles were seen to transfer pollen from male phase to female phase inflorescences. Successful fertilisation was only effected if pollen was transferred on the same night from a male inflorescence 30 m or less away. Pollen is psilate and typical of beetle pollinated Araceae. Berries ripen approximately 70 d after fertilization and ripen basisetally in the infructescence.

scholarly journals Male flowers of Aconitum compensate for toxic pollen with increased floral signals and rewards for pollinators

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
A.-L. Jacquemart ◽  
C. Buyens ◽  
M.-F. Hérent ◽  
J. Quetin-Leclercq ◽  
G. Lognay ◽  
...  
Keyword(s):  
Larval Food ◽  
Chemical Defences ◽  
Toxic Nectar ◽  
Pollen Transfer Efficiency ◽  
Aconitum Napellus ◽  
Female Phase ◽  
Male Phase ◽  
Male Flowers ◽  
Nectar Rewards ◽  
Toxic Pollen

Abstract Many plants require animal pollinators for successful reproduction; these plants provide pollinator resources in pollen and nectar (rewards) and attract pollinators by specific cues (signals). In a seeming contradiction, some plants produce toxins such as alkaloids in their pollen and nectar, protecting their resources from ineffective pollinators. We investigated signals and rewards in the toxic, protandrous bee-pollinated plant Aconitum napellus, hypothesizing that male-phase flower reproductive success is pollinator-limited, which should favour higher levels of signals (odours) and rewards (nectar and pollen) compared with female-phase flowers. Furthermore, we expected insect visitors to forage only for nectar, due to the toxicity of pollen. We demonstrated that male-phase flowers emitted more volatile molecules and produced higher volumes of nectar than female-phase flowers. Alkaloids in pollen functioned as chemical defences, and were more diverse and more concentrated compared to the alkaloids in nectar. Visitors actively collected little pollen for larval food but consumed more of the less-toxic nectar. Toxic pollen remaining on the bee bodies promoted pollen transfer efficiency, facilitating pollination.

scholarly journals Linking pollinator efficiency to patterns of pollen limitation: small bees exploit the plant–pollinator mutualism

2018 ◽  
Vol 285 (1880) ◽  
pp. 20180635 ◽  
Author(s):  
Matthew H. Koski ◽  
Jennifer L. Ison ◽  
Ashley Padilla ◽  
Angela Q. Pham ◽  
Laura F. Galloway
Keyword(s):  
Pollen Limitation ◽  
Pollen Deposition ◽  
Pollinator Efficiency ◽  
Flower Visitation ◽  
Female Phase ◽  
Male Phase ◽  
Single Flower ◽  
Floral Visitation ◽  
Low Efficiency ◽  
Plant Pollinator

Seemingly mutualistic relationships can be exploited, in some cases reducing fitness of the exploited species. In plants, the insufficient receipt of pollen limits reproduction. While infrequent pollination commonly underlies pollen limitation (PL), frequent interactions with low-efficiency, exploitative pollinators may also cause PL. In the widespread protandrous herb Campanula americana , visitation by three pollinators explained 63% of the variation in PL among populations spanning the range. Bumblebees and the medium-sized Megachile campanulae enhanced reproductive success, but small solitary bees exacerbated PL. To dissect mechanisms behind these relationships, we scored sex-specific floral visitation, and the contributions of each pollinator to plant fitness using single flower visits. Small bees and M. campanulae overvisited male-phase flowers, but bumblebees frequently visited female-phase flowers. Fewer bumblebee visits were required to saturate seed set compared to other bees. Scaling pollinator efficiency metrics to populations, small bees deplete large amounts of pollen due to highly male-biased flower visitation and infrequent pollen deposition. Thus, small bees reduce plant reproduction by limiting pollen available for transfer by efficient pollinators, and appear to exploit the plant–pollinator mutualism, acting as functional parasites to C. americana . It is therefore unlikely that small bees will compensate for reproductive failure in C. americana when bumblebees are scarce.

scholarly journals Terpenes and their oxidation products in the French Landes forest: insights from Vocus PTR-TOF measurements

2020 ◽  
Vol 20 (4) ◽  
pp. 1941-1959 ◽  
Author(s):  
Haiyan Li ◽  
Matthieu Riva ◽  
Pekka Rantala ◽  
Liine Heikkinen ◽  
Kaspar Daellenbach ◽  
...  
Keyword(s):  
Gas Phase ◽  
Detection Efficiency ◽  
Ambient Air ◽  
Reaction Rates ◽  
Early Morning ◽  
Oxidation Products ◽  
Atmospheric Oxidation ◽  
Organic Nitrates ◽  
Reaction Products ◽  
Wide Range

Abstract. The capabilities of the recently developed Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF) are reported for the first time based on ambient measurements. With the deployment of the Vocus PTR-TOF, we present an overview of the observed gas-phase (oxygenated) molecules in the French Landes forest during summertime 2018 and gain insights into the atmospheric oxidation of terpenes, which are emitted in large quantities in the atmosphere and play important roles in secondary organic aerosol production. Due to the greatly improved detection efficiency compared to conventional PTR instruments, the Vocus PTR-TOF identifies a large number of gas-phase signals with elemental composition categories including CH, CHO, CHN, CHS, CHON, CHOS, and others. Multiple hydrocarbons are detected, with carbon numbers up to 20. Particularly, we report the first direct observations of low-volatility diterpenes in the ambient air. The diurnal cycle of diterpenes is similar to that of monoterpenes and sesquiterpenes but contrary to that of isoprene. Various types of terpene reaction products and intermediates are also characterized. Generally, the more oxidized products from terpene oxidations show a broad peak in the day due to the strong photochemical effects, while the less oxygenated products peak in the early morning and/or in the evening. To evaluate the importance of different formation pathways in terpene chemistry, the reaction rates of terpenes with main oxidants (i.e., hydroxyl radical, OH; ozone, O3; and nitrate radical, NO3) are calculated. For the less oxidized non-nitrate monoterpene oxidation products, their morning and evening peaks have contributions from both O3- and OH-initiated monoterpene oxidation. For the monoterpene-derived organic nitrates, oxidations by O3, OH, and NO3 radicals all contribute to their formation, with their relative roles varying considerably over the course of the day. Through a detailed analysis of terpene chemistry, this study demonstrates the capability of the Vocus PTR-TOF in the detection of a wide range of oxidized reaction products in ambient and remote conditions, which highlights its importance in investigating atmospheric oxidation processes.

scholarly journals Intraspecific Seasonal Variation of Flowering Synchronization in a Heterodichogamous Tree

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1509
Author(s):  
Noemi Tel-Zur ◽  
Tamar Keasar
Keyword(s):  
Genetic Diversity ◽  
Seasonal Variation ◽  
Phase Duration ◽  
Male And Female ◽  
Flowering Synchrony ◽  
Flowering Season ◽  
Hand Pollination ◽  
Female Phase ◽  
Male Phase ◽  
Phase Differences

Heterodichogamous reproduction in plants involves two flowering morphs, reciprocal in their timing of male and female sexual functions. The degree of synchrony in floral sex phase, within and between individuals of each morph, determines the flowers’ potential fertilization partners. Complete within-morph synchrony enables across-morph mating alone, whereas unsynchronized floral sex phases may allow fertilization within a plant individual (geitonogamy) or within a morph. We documented the disruption of flowering synchrony in the heterodichogamous Ziziphus spina-christi towards the end of its seven-month flowering season. This desert tree has self-incompatible, protandrous, short-lived (2-day) flowers that open before dawn (‘Early’ morph) or around noon (‘Late’ morph). We counted flowers in the male and female phase on flowering branches that were sampled monthly during the 2016–2018 flowering seasons. In 2018, we also tagged flowers and followed their sex-phase distributions over two days at the start, middle, and end of the season. The switch to the female phase was delayed at the end-season (November-December), and 74% of the flowers did not develop beyond their male phase. Differences in male-phase duration resulted in asynchrony among flowers within each tree and among trees of both flowering morphs. Consequently, fertilization between trees of the same morph becomes potentially possible during the end-season. In controlled hand-pollination assays, some within-morph fertilizations set fruit. The end-season breakdown of synchronous flowering generates variability within morphs and populations. We suggest that this variability may potentially enable new mating combinations in a population and enhance its genetic diversity.

scholarly journals Photosynthetic performance of rock-colonising lichens in the Mountain Zebra National Park, South Africa

Koedoe ◽  
1993 ◽  
Vol 36 (1) ◽  
Author(s):  
Dirk Wessels ◽  
Ludger Kappen
Keyword(s):  
South Africa ◽  
Volcanic Rock ◽  
National Park ◽  
Ambient Air ◽  
Early Morning ◽  
Photosynthetic Performance ◽  
The Other ◽  
Air Temperatures ◽  
Desert Regions

The photosynthetic behaviour of endolithic andepilithic lichens characteristic of sedimentary and volcanic rock was investigated in situ in the Mountain Zebra National Park, South Africa. The park forms part of an inland semi-desert known as the Karoo, in the Cape Province. Temperatures within Balfour sandstone were monitored, the results showing that during the early morning, temperatures within the sandstone were nearly 5@C lower than ambient air temperatures. This may enhance the frequency of water condensing on the sandstone, which may be particularly important for the endoliths Leciclea aff. sarcogynoides and Sarcogyne cf. austroafricana. Maximum photosynthetic rates of the investigated species were found at temperatures between 20@C and 30@C, far higher than the recorded optimum temperatures for lichens from temperate and desert regions. Parmelia chlorea was the most productive species. Compared to the other epiliths, Peltula capensis was found to be a moderately productive species. The photosynthetic gain of Leciclea aff. sarcogynoides and Sarcogyne cf. austro-africana was low, but the photosynthetic gain of these two species still exceeded that of Acarospora sp.

scholarly journals Temporal variability, sources, and sinks of C<sub>1</sub>-C<sub>5</sub> alkyl nitrates in coastal New England

2010 ◽  
Vol 10 (4) ◽  
pp. 1865-1883 ◽  
Author(s):  
R. S. Russo ◽  
Y. Zhou ◽  
K. B. Haase ◽  
O. W. Wingenter ◽  
E. K. Frinak ◽  
...  
Keyword(s):  
New England ◽  
New Hampshire ◽  
Dry Deposition ◽  
Gulf Of Maine ◽  
Ambient Air ◽  
Early Morning ◽  
Secondary Source ◽  
Alkyl Nitrates ◽  
Mixing Ratios ◽  
Alkyl Nitrate

Abstract. Seven C1-C5 alkyl nitrates were measured both on the mainland and off the coast of New Hampshire using gas chromatographic techniques. Five separate data sets are presented to characterize the seasonal and diurnal trends and the major sources and loss processes of these compounds. Based on in situ measurements conducted at the University of New Hampshire (UNH) Atmospheric Observing Station at Thompson Farm (TF) located in southeast NH during winter (January–February) 2002, summer (June–August) 2002, summer (July–August) 2004, and on daily canister samples collected at midday from January 2004–February 2008, the median total alkyl nitrate mixing ratio (ΣRONO2) was 23–25 pptv in winter and 14–16 pptv in summer. During summers 2002 and 2004, MeONO2 decreased overnight and reached minimum hourly average mixing ratios in the early morning. Comparison with wind speed and trace gas trends suggested that dry deposition contributed to the early morning MeONO2 minimum which is a previously unaccounted for removal mechanism. The mean dry deposition rate and velocity of MeONO2 was estimated to be −0.5 nmol m−2 hr−1 and 0.13 cm s−1, respectively. Results from ambient air and surface seawater measurements made onboard the NOAA R/V Ronald H. Brown in the Gulf of Maine during the 2002 New England Air Quality Study and from ambient canister samples collected throughout the Great Bay estuary in August 2003 are also presented. Comparisons between the alkyl nitrate trends with anthropogenic and marine tracers suggest that a marine source of alkyl nitrates is not significant in coastal New England. Given the apparent prominence of a secondary source, comparisons between observed and predicted alkyl nitrate/parent hydrocarbon ratios were made which demonstrated that background mixing ratios have a continuous and prevalent influence on the alkyl nitrate distribution.

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