scholarly journals Pollination of two species of Vellozia (Velloziaceae) from high-altitude quartzitic grasslands, Brazil

2007 ◽  
Vol 21 (2) ◽  
pp. 325-333 ◽  
Author(s):  
Claudia Maria Jacobi ◽  
Mário César Laboissiérè del Sarto
Keyword(s):  
High Altitude ◽  
Pollen Limitation ◽  
Cross Pollination ◽  
Se Brazil ◽  
Self Compatibility ◽  
Leaf Cutting ◽  
Pollen Theft ◽  
Floral Displays ◽  
Facultative Xenogamy ◽  
And Control

The pollinators and breeding system of two species of Vellozia (Velloziaceae) from high-altitude quartzitic grasslands in SE Brazil were studied. Vellozia leptopetala is shrubby and grows solely on rocky outcrops, V. epidendroides is herbaceous and grows on stony soils. Both bear solitary, hermaphrodite flowers, and have massive, short-lasting annual blooms. We evaluated the level of self-compatibility and need for pollinators of 50 plants of each species and 20-60 flowers per treatment: hand self- and cross-pollination, spontaneous pollination, agamospermy and control. The behavior of floral visitors on flowers and within plants was recorded. Both species are mostly self-incompatible, but produce a small number of seeds by self-fertilization. The pollen-ovule ratio suggests facultative xenogamy. They were visited primarily by bees, of which the most important pollinators were two leaf-cutting bees (Megachile spp.). Vellozia leptopetala was also pollinated by a territorial hummingbird. Low natural seed production compared to cross-pollination seed numbers suggests that pollen limitation is the main cause of low seed set. This was attributed to the combined effect of five mechanisms: selfing prior to anthesis, enhanced geitonogamy as a result of large floral displays, low number of visits per flower for the same reason, pollen theft by many insect species, and, in V. leptopetala, delivery of mixed pollen loads on the stigma as a consequence of hummingbird promiscuity.

scholarly journals Autonomous pollination alleviates pollen limitation in the endemic Cienfuegosia yucatanensis Millsp. (Malvaceae)

2020 ◽  
Vol 99 (1) ◽  
pp. 80-91
Author(s):  
Víctor Parra-Tabla ◽  
Conchita Alonso
Keyword(s):  
Seed Production ◽  
Inbreeding Depression ◽  
Seed Weight ◽  
Pollen Limitation ◽  
Pollen Tubes ◽  
Pollen Deposition ◽  
Cross Pollination ◽  
The North ◽  
Hand Pollination ◽  
Self Compatibility

Background: Self-compatibility is common on endemic plant species, but pollen limitation and self-pollination could be risk factors. Study species: The endemic Cienfuegosia yucatanensis (Malvaceae), whose distribution is mainly restricted to the north coast of the peninsula of Yucatán, México. Questions: a) Are flowers of C. yucatanensis autonomous for pollination? b) Are C. yucatanensis fruit or seed-set limited by pollen deposition? and, c) Is there evidence of early inbreeding depression in C. yucatanensis? Study sites and dates: Two sites in the north of the peninsula of Yucatán in a seasonally dry scrubland, in the rainy season of 2013 and 2014. Methods: Number of flowers and fruits were weekly recorded. Flowers were collected to count the number of conspecific pollen load and the number of pollen tubes. Autonomous pollination and pollen limitation were evaluated with a hand-pollination experiment. Inbreeding depression on fruit and seed production, and seed weight was evaluated. Results: Flower and fruit production occur simultaneously and last from August to October. Conspecific pollen deposition on stigmas occurred through the whole flowering season and a maximum of pollen tubes was observed in August. Autonomous pollination treatment lead to similar fruit and seed production than cross-pollination, but open pollination produced significantly more seeds. No significant differences among self- and cross-pollination treatments on fruit and seed production or seed weight, were found.  Conclusions: Our results suggest that self-compatibility combined with a relatively efficient autonomous pollination, are suitable mechanisms for the reproductive assurance in C. yucatanensis, with no apparent effects of early inbreeding depression.

Simulation of thermal stress and control measures for rock-filled concrete dam in high-altitude and cold regions

2021 ◽  
Vol 230 ◽  
pp. 111721
Author(s):  
Yuxiang Zhang ◽  
Jianwen Pan ◽  
Xinjian Sun ◽  
Jijun Feng ◽  
Dengqiang Sheng ◽  
...  
Keyword(s):  
Thermal Stress ◽  
High Altitude ◽  
Control Measures ◽  
Concrete Dam ◽  
Cold Regions ◽  
And Control

Pollen limitation and xenia effects in a cultivated mass-flowering tree, Macadamia integrifolia (Proteaceae)

2021 ◽  
Author(s):  
Stephen J Trueman ◽  
Wiebke Kämper ◽  
Joel Nichols ◽  
Steven M Ogbourne ◽  
David Hawkes ◽  
...  
Keyword(s):  
Food Production ◽  
Fruit Set ◽  
Pollen Limitation ◽  
Pollination Services ◽  
Mass Flowering ◽  
Shell Mass ◽  
Cross Pollination ◽  
Macadamia Integrifolia ◽  
Kernel Yield ◽  
Flowering Tree

Abstract Background and Aims Pollen limitation is most prevalent among bee-pollinated plants, self-incompatible plants, and tropical plants. However, we have very little understanding of the extent to which pollen limitation affects fruit set in mass-flowering trees despite tree crops accounting for at least 600 million tons of the 9,200 million tons of annual global food production. Methods We determined the extent of pollen limitation in a bee-pollinated, partially self-incompatible, subtropical tree by hand cross-pollinating the majority of flowers on mass-flowering macadamia (Macadamia integrifolia) trees that produce about 200,000–400,000 flowers. We measured tree yield and kernel quality and estimated final fruit set. We genotyped individual kernels by MassARRAY to determine levels of outcrossing in orchards and assess paternity effects on nut quality. Key Results Macadamia trees were pollen limited. Supplementary cross-pollination increased nut-in-shell yield, kernel yield and fruit set by as much as 97%, 109% and 92%, respectively. The extent of pollen limitation depended upon the proximity of experimental trees to trees of another cultivar because macadamia trees were highly outcrossing. Between 84% and 100% of fruit arose from cross-pollination, even at 200 m (25 rows) from orchard blocks of another cultivar. Large variations in nut-in-shell mass, kernel mass, kernel recovery and kernel oil concentration were related to differences in fruit paternity, including between self-pollinated and cross-pollinated fruit, thus demonstrating pollen-parent effects on fruit quality, i.e. xenia. Conclusions This study is the first to demonstrate pollen limitation in a mass-flowering tree. Improved pollination led to increased kernel yield of 0.31–0.59 tons per hectare, which equates currently to higher farm-gate income of approximately US3,720–US7,080 per hectare. The heavy reliance of macadamia flowers on cross-pollination and the strong xenia effects on kernel mass demonstrate the high value that pollination services can provide to food production.

Analysis of emissions from various driving cycles based on real driving measurements obtained in a high-altitude city

2020 ◽  
Vol 234 (6) ◽  
pp. 1563-1571 ◽  
Author(s):  
Meng Lyu ◽  
Xiaofeng Bao ◽  
Yunjing Wang ◽  
Ronald Matthews
Keyword(s):  
High Altitude ◽  
Real World ◽  
Vehicle Emissions ◽  
Control Strategies ◽  
Driving Cycle ◽  
Specific Power ◽  
Test Cycle ◽  
Light Duty ◽  
And Control ◽  
Light Duty Vehicles

Vehicle emissions standards and regulations remain weak in high-altitude regions. In this study, vehicle emissions from both the New European Driving Cycle and the Worldwide harmonized Light-duty driving Test Cycle were analyzed by employing on-road test data collected from typical roads in a high-altitude city. On-road measurements were conducted on five light-duty vehicles using a portable emissions measurement system. The certification cycle parameters were synthesized from real-world driving data using the vehicle specific power methodology. The analysis revealed that under real-world driving conditions, all emissions were generally higher than the estimated values for both the New European Driving Cycle and Worldwide harmonized Light-duty driving Test Cycle. Concerning emissions standards, more CO, NOx, and hydrocarbons were emitted by China 3 vehicles than by China 4 vehicles, whereas the CO2 emissions exhibited interesting trends with vehicle displacement and emissions standards. These results have potential implications for policymakers in regard to vehicle emissions management and control strategies aimed at emissions reduction, fleet inspection, and maintenance programs.

Leaf-cutting ants revisited: Towards rational management and control

2012 ◽  
Vol 58 (3) ◽  
pp. 225-247 ◽  
Author(s):  
James Montoya-Lerma ◽  
Carolina Giraldo-Echeverri ◽  
Inge Armbrecht ◽  
Alejandro Farji-Brener ◽  
Zoraida Calle
Keyword(s):  
Leaf Cutting ◽  
Rational Management ◽  
And Control

Fuel Systems For Supersonic Engines

1958 ◽  
Vol 62 (573) ◽  
pp. 654-658
Author(s):  
E. A. Simonis
Keyword(s):  
Combustion Chamber ◽  
High Altitude ◽  
Control Problems ◽  
Fuel System ◽  
Complex Control ◽  
Supersonic Aircraft ◽  
Engine Combustion ◽  
Main Engine ◽  
And Control

The advent of the high altitude supersonic aircraft has brought in its train a whole host of complex control problems. As far as the engine manufacture is concerned, these are perhaps best indicated in the diagrammatic layout shown in Fig. 1It is not my intention however, to go into the question of multiplicity of controls and their proper co-ordination, nor will I venture into the abstruse province of stability. I should like instead to concentrate on the fuel system itself, i.e. the supply and control of fuel to the main engine combustion chamber.

Very Low Fruit : Flower Ratios in Grevillea (Proteaceae) are Independent of Breeding System

1998 ◽  
Vol 46 (4) ◽  
pp. 465 ◽  
Author(s):  
Luise Hermanutz ◽  
David Innes ◽  
Andrew Denham ◽  
Robert Whelan
Keyword(s):  
Fruit Set ◽  
Pollen Limitation ◽  
Breeding Systems ◽  
Mature Fruit ◽  
Closely Related Species ◽  
Woody Perennials ◽  
The Family ◽  
Self Compatibility ◽  
Species Specific

Members of the family Proteaceae have extremely low mature fruit : flower (FR : FL) ratios (range 0.001–0.163) compared with other temperate, hermaphroditic, woody perennials. Sutherland’s (1986) survey of FR : FL ratios indicated that compatibility was an important factor explaining levels of fruit set. The role of compatibility in regulating FR : FL ratios was tested in five closely related species of Grevillea (Proteaceae). Species-specific compatibility was compared using the self-compatibility index (SI = ratio of selfed fruit set to crossed fruit set) calculated at fruit initiation to minimise the confounding effect of other post-fertilisation fruit losses, such as inbreeding depression and pre-dispersal predation. Fruit : flower ratios at initiation ranged from 0.041–0.249, and at maturity 0.015–0.096. Grevillea species showed highly variable breeding systems: G. linearifolia was self-incompatible (SI = 0.003), G. sphacelata, G. mucronulata, and G. oleoides were partially self-compatible (SI = 0.07–0.28) and G. longifolia was self-compatible (SI = 0.61). Intrapopulation variability in the level of self-incompatibility was high in all species but G. linearifolia. The correlation between SI and FR: FL ratios was non-significant, indicating that compatibility has a minimal effect on fruit set in the Grevillea species studied, and that these data, together with other data on proteaceous species do not support trends observed in Sutherland’s survey. Low FR : FL ratios resulted from of a combination of pollen limitation, and high levels of flower and fruit predation.

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