scholarly journals Extreme Drought Affects Visitation and Seed Set in a Plant Species in the Central Chilean Andes Heavily Dependent on Hummingbird Pollination

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1553
Author(s):  
Mary T. K. Arroyo ◽  
Valeria Robles ◽  
Ítalo Tamburrino ◽  
Jaime Martínez-Harms ◽  
René D. Garreaud ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Plant Species ◽  
Standing Crop ◽  
Seed Set ◽  
Austral Summer ◽  
Flower Head ◽  
Floral Longevity ◽  
Visitation Frequency ◽  
Nectar Standing Crop ◽  
Nectar Concentration

Rising temperatures and increasing drought in Mediterranean-type climate areas are expected to affect plant–pollinator interactions, especially in plant species with specialised pollination. Central Chile experienced a mega drought between 2010 and 2020 which reached an extreme in the austral summer of 2019–2020. Based on intensive pollinator sampling and floral studies we show that the subalpine form of Mutisia subulata (Asteraceae) is a specialised hummingbird-pollinated species. In a two-year study which included the severest drought year, we quantified visitation frequency, flower-head density, flower-head visitation rates, two measures of floral longevity, nectar characteristics and seed set and monitored climatic variables to detect direct and indirect climate-related effects on pollinator visitation. Flower-head density, nectar standing crop and seed set were significantly reduced in the severest drought year while nectar concentration increased. The best model to explain visitation frequency included flower-head density, relative humidity, temperature, and nectar standing crop with highly significant effects of the first three variables. Results for flower-head density suggest hummingbirds were able to associate visual signals with reduced resource availability and/or were less abundant. The negative effect of lower relative humidity suggests the birds were able to perceive differences in nectar concentration. Reduced seed set per flower-head together with the availability of far fewer ovules in the 2019–2020 austral summer would have resulted in a major reduction in seed set. Longer and more intense droughts in this century could threaten local population persistence in M. subulata.

scholarly journals Pollinator importance networks illustrate the crucial value of bees in a highly speciose plant community

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Gavin Ballantyne ◽  
Katherine C. R. Baldock ◽  
Luke Rendell ◽  
P. G. Willmer
Keyword(s):  
Plant Species ◽  
Community Level ◽  
Taxonomic Resolution ◽  
Pollen Deposition ◽  
Pollinator Effectiveness ◽  
Flower Visitors ◽  
Pollinator Importance ◽  
Visitation Frequency ◽  
Pollinator Performance ◽  
Number Of Plant Species

AbstractAccurate predictions of pollination service delivery require a comprehensive understanding of the interactions between plants and flower visitors. To improve measurements of pollinator performance underlying such predictions, we surveyed visitation frequency, pollinator effectiveness (pollen deposition ability) and pollinator importance (the product of visitation frequency and effectiveness) of flower visitors in a diverse Mediterranean flower meadow. With these data we constructed the largest pollinator importance network to date and compared it with the corresponding visitation network to estimate the specialisation of the community with greater precision. Visitation frequencies at the community level were positively correlated with the amount of pollen deposited during individual visits, though rarely correlated at lower taxonomic resolution. Bees had the highest levels of pollinator effectiveness, with Apis, Andrena, Lasioglossum and Osmiini bees being the most effective visitors to a number of plant species. Bomblyiid flies were the most effective non-bee flower visitors. Predictions of community specialisation (H2′) were higher in the pollinator importance network than the visitation network, mirroring previous studies. Our results increase confidence in existing measures of pollinator redundancy at the community level using visitation data, while also providing detailed information on interaction quality at the plant species level.

scholarly journals How does timing of flowering affect competition for pollinators, flower visitation and seed set in an early spring grassland plant?

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Sandra Kehrberger ◽  
Andrea Holzschuh
Keyword(s):  
Species Interactions ◽  
Seed Set ◽  
Weather Conditions ◽  
Early Spring ◽  
Flowering Plants ◽  
Early Flowering ◽  
Flower Visitation ◽  
Floral Longevity ◽  
Visitation Rates ◽  
Phenological Shifts

Abstract Knowledge on how the timing of flowering is related to plant fitness and species interactions is crucial to understand consequences of phenological shifts as they occur under climate change. Early flowering plants may face advantages of low competition for pollinators and disadvantages of low pollinator abundances and unfavourable weather conditions. However, it is unknown how this trade-off changes over the season and how the timing affects reproductive success. On eight grasslands we recorded intra-seasonal changes in pollinators, co-flowering plants, weather conditions, flower visitation rates, floral longevity and seed set of Pulsatilla vulgaris. Although bee abundances and the number of pollinator-suitable hours were low at the beginning of the season, early flowers of P. vulgaris received higher flower visitation rates and estimated total number of bee visits than later flowers, which was positively related to seed set. Flower visitation rates decreased over time and with increasing number of co-flowering plants, which competed with P. vulgaris for pollinators. Low interspecific competition for pollinators seems to be a major driver for early flowering dates. Thus, non-synchronous temporal shifts of co-flowering plants as they may occur under climate warming can be expected to strongly affect plant-pollinator interactions and the fitness of the involved plants.

INFLUENCE OF MOISTURE STRESS, RELATIVE HUMIDITY AND OXYGEN DIFFUSION RATE ON SEED SET AND YIELD OF WHEAT

1969 ◽  
Vol 49 (1) ◽  
pp. 29-37 ◽  
Author(s):  
C. A. Campbell ◽  
D. S. McBean ◽  
D. G. Green
Keyword(s):  
Soil Moisture ◽  
Relative Humidity ◽  
Oxygen Diffusion ◽  
Seed Set ◽  
Diffusion Rate ◽  
Moisture Stress ◽  
Morphological Examination ◽  
Hand Pollination ◽  
Growth Chamber Studies ◽  
Oxygen Diffusion Rate

The influence of oxygen diffusion rate (ODR) and relative humidity (RH) on seed set and yield of wheat was investigated in two growth chamber studies. In one study, plants grown at 80% RH were compared with those grown at 60%. In the other, plants grown in pots without supplemental aeration were compared with plants grown in aerated pots.Wheat grown at low soil moisture stress (between 25 and 16%) produced significantly poorer seed set and grain yield than those grown at higher stress (between 25 and 10%). Seed set was less severely reduced in Manitou than in Chinook. Plants grown at low moisture stress and 60% RH gave better seed set than those grown at 80%. However, even at 60% RH, seed set was less than 65%.The oxygen diffusion rates in unaerated pots were 28 × 10−8, 100 × 10−8 and 200 × 10−8 g cm−2min−1 at 25%, 16% and 10% soil moisture (by weight). In aerated pots, ODR at 25% and 16% soil moisture were 82 × 10−8 and 180 × 10−8 g cm−2min−1, respectively.Seed set and grain yields of Chinook wheat grown at low moisture stress were increased from 54 to 82% and from 11.5 to 26.7 g/pot by improving the soil aeration.The anthers, especially the pollen, were the main reproductive components damaged by poor aeration. This was demonstrated by morphological examination and by hand-pollination experiments. Poor seed set was confined primarily to the top two-thirds of the head.

Anthracnose of Florida Beggarweed (Desmodium tortuosum) Caused byColletotrichum truncatum

Weed Science ◽  
1988 ◽  
Vol 36 (3) ◽  
pp. 329-334 ◽  
Author(s):  
John Gardina ◽  
Robert H. Littrell ◽  
Richard T. Hanlin
Keyword(s):  
Relative Humidity ◽  
Host Specificity ◽  
Plant Species ◽  
Fungal Pathogen ◽  
Disease Development ◽  
Colletotrichum Truncatum ◽  
Optimum Conditions ◽  
Cotyledon Stage ◽  
Chamber Studies ◽  
Growth Chamber Studies

Greenhouse and growth chamber studies were conducted to determine conditions for infection of the fungal pathogenColletotrichum truncatum(Schw.) Andrus and Moore on Florida beggarweed (Desmodium tortuosum(Sw.) DC. # DEDTO and to determine the host specificity of this fungus. Optimum conditions for disease development were 14 to 16 h incubation in 100% relative humidity (RH) at 24 to 29 C. Control of Florida beggarweed with 105to 107C. truncatumspores/ml was greatest in the cotyledon stage and decreased with plant age. Ten of 18Desmodiumspecies tested were susceptible to the Florida beggarweed isolate ofC. truncatumbut 13 other plant species and varieties were resistant and 61 were immune.

scholarly journals Identification and Evaluation of Factors Affecting Nectar Volume and Concentrations of Croton Macrostachyus Hochst.ex Delile

2021 ◽  
Author(s):  
Kasim Roba Jilo ◽  
Getachew Sime
Keyword(s):  
Relative Humidity ◽  
Sucrose Concentration ◽  
Abiotic Factors ◽  
Time Of Day ◽  
Factors Affecting ◽  
Nectar Volume ◽  
Biotic And Abiotic Factors ◽  
Honey Production ◽  
Nectar Concentration ◽  
Croton Macrostachyus

Abstract Background: Secretion of nectar is highly influenced by many factors and the objective of the study was also to evaluate factors affecting concentrations of nectar of Croton macrostachyus Hochst.ex Delile. Age of plants highly affect nectar concentration and volume. Honey quality and its medicinal values depends on plants species variety and their sucrose concentration quality and quantity which is governed by many biotic and abiotic factors as well micro climate of the area. Wholesale of nectar and concentration of tend to show more differences in time of day for species study undertaken.Results: As results publicized that nectar concentration and volume of youngest age was not more affected by temperature and relative humidity like that of medium and oldest ages. Temperature and age have significant effect on volume (p = 0.0001) and their interactions is also significant (p = 0.01145). Temperature has significant effects on nectar concentration (p = 0.000). Interaction of relative humidity, time, and layers has significant effects on nectar concentration (p = 0.0024012). The oldest plants had the highest concentration of 10.1 w/w mornings and afternoon 36.5 w/w at 4:00 PM for whereas medium plants had nectar concentration of 5.7 w/w morning and afternoon 16.7 w/w and the smaller or younger plants had nectar concentration of 2.7 w/w mornings and afternoon 9.1 w/w and this shows age significantly affect nectar concentration and volume.Conclusions:Concentration and volume were affected by many biotic and abiotic factors. I conclude imminent fever intensification could harm nectar production since for croton also no nectar could be collected at 30 C⁰ and no nectar recreation was observed after this peak temperature this indicates environmental change can increase the temperature which will have negative influences on honey production in the future unless we combat against climate change which will affect honey production and productivity for the country and we will lose honey and its medicinal values also.

The Timing and Patterning of Flowering

2011 ◽  
Author(s):  
Pat Willmer
Keyword(s):  
Reproductive Success ◽  
Plant Species ◽  
Flowering Phenology ◽  
Flowering Period ◽  
Flower Longevity ◽  
Pollen Transfer ◽  
Flowering Pattern ◽  
Floral Longevity ◽  
Pollen Receipt

This chapter examines the factors that affect the timing and patterning of flowering, as well as the effects of different flowering patterns on pollination outcomes. Plants should flower in ways that maximize their own reproductive success. The “flowering pattern” is a composite of the timing and frequency of individual flowers opening, and also of floral longevity. These phenological factors vary between and within species. Flowering phenology can influence the plant’s manipulation of its visitors in ways that should increase either or both of pollen transfer and pollen receipt. The chapter first considers the frequency of flowering and the shape of the flowering period before discussing flower longevity and flowering period. It also explores the question of how big a flower should be, how many flowers a plant should have at any one time, what determines the phenological parameters for a particular plant species, and where the flowers should be placed.

Sodium Bicarbonate Antagonism of 2,4-D Amine

1990 ◽  
Vol 4 (3) ◽  
pp. 588-591 ◽  
Author(s):  
John D. Nalewaja ◽  
Zenon Woznica ◽  
Frank A. Manthey
Keyword(s):  
Relative Humidity ◽  
Low Temperature ◽  
Sodium Bicarbonate ◽  
Plant Species ◽  
Water Source ◽  
Water Spray ◽  
Spray Volume

2,4-D diethanolamine control of kochia was influenced by the source of water used as the spray carrier. Sodium bicarbonate in one water source related to the reduced kochia control. Sodium bicarbonate in a water spray carrier antagonized 2,4-D control of all plant species evaluated. Antagonism increased with the tolerance of a species to 2,4-D, concentration of sodium bicarbonate, and spray volume. Sodium bicarbonate antagonism of 2,4-D phytotoxicity was greatest with low temperature and relative humidity.

Effectiveness of diurnal and nocturnal pollination of two milkweeds

1980 ◽  
Vol 58 (16) ◽  
pp. 1744-1746 ◽  
Author(s):  
Robert I. Bertin ◽  
Mary F. Willson
Keyword(s):  
Reproductive Success ◽  
Plant Species ◽  
Seed Set ◽  
Relative Effectiveness ◽  
Asclepias Syriaca ◽  
Nectar Production ◽  
Selective Abortion ◽  
Nocturnal Pollinators ◽  
Diurnal Species

The relative effectiveness of diurnal and nocturnal pollinators of two milkweed species, Asclepias syriaca and A. vcerticillata, was assessed experimentally and related to patterns of nectar production. Nocturnal pollinators inserted and removed fewer pollinia than diurnal vectors but caused equal pod set, and in A. syriaca, caused greater seed set. We suggest that observed peak nectar production patterns are adaptive in attracting nocturnal pollinators that may be of higher quality than diurnal species. This is one of the first attempts to compare the relative effectiveness of diurnal and nocturnal pollinators of any plant species. The excess of vector visits over that needed to obtain maximum pod set may allow selective abortion and (or) be adaptive in increasing reproductive success through pollinia donation.

scholarly journals Notes on the flowering and pollination of the endemic grassland Aloe reitzii var. reitzii (Asphodelaceae)

Bothalia ◽  
2017 ◽  
Vol 47 (2) ◽  
Author(s):  
Craig T. Symes
Keyword(s):  
South Africa ◽  
Standing Crop ◽  
Bird Species ◽  
Camera Trap ◽  
Camera Traps ◽  
Pollination Biology ◽  
Nectar Volume ◽  
Invertebrate Species ◽  
Nectar Standing Crop ◽  
Insight Into

Background: Aloe reitzii var. reitzii is a succulent with a restricted distribution in the montane grassland of eastern South Africa. It is a summer (late January–March) flowering succulent that grows on rocky outcrops at 1000 m–1600 m, and the conspicuous inflorescences suggest a pollination system focused towards birds.Objectives: To understand more about the pollination biology of A. reitzii var. reitzii.Methods: Nectar standing crop (flower volume and concentration) and the proportion of plants flowering were recorded. Camera traps and observations were used to record visitors to A. reitzii var. reitzii inflorescences.Results: Nectar volume was 36 μL ± 27 μL per flower (range 6 μL–93 μL; n = 27) and concentration was 16.5% ± 1.7% (range 13.5% – 19.5%). Camera trap observations, where 18.9% of all plants were observed flowering, recorded the three bird species Cape Weaver, Ploceus capensis, Malachite Sunbird, Nectarinia famosa and Greater Double-collared Sunbird, Cinnyris afer (60.4%, 27.1% and 12.5% of plant visits, respectively) visiting inflorescences.Conclusion: Because birds are important pollinators for many Aloe species, it is assumed that the bird species detected visiting A. reitzii var. reitzii are similarly important pollinators. At least 10 invertebrate species and sengi (Elephantulus sp.) were also recorded as visitors to flowers, but they may be less important pollinators than specialist and generalist avian nectarivores. This study provides further insight into the pollination biology of a diverse, and ecologically important, succulent genus in Africa.

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