Journal articles: 'Stigmatic surfaces'

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Carmo-Oliveira, Renata, and Berta Lange de Morretes. "Stigmatic surface in the Vochysiaceae: reproductive and taxonomic implications." Acta Botanica Brasilica 23, no. 3 (September 2009): 780–85. http://dx.doi.org/10.1590/s0102-33062009000300018.

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The Vochysiaceae are Neotropical trees and shrubs, common in the savanna areas in Central Brazil (Cerrados). The family has been traditionally divided into two tribes: Erismeae, with three genera, and Vochysieae, with five genera. We investigated the stigmatic surface of six Vochysiaceae species, belonging to four genera of Vochysieae: Vochysia, Salvertia, Callisthene and Qualea. Flowers and buds at different developmental stages were collected. Morphological features were observed on fresh material and stigmatic receptivity was inferred based on esterasic activity. Pistils were fixed and embedded in paraplast and sectioned on a rotary microtome; the sections were stained before histological analysis. Stigmas of open flowers were also observed by scanning electron microscopy. Stigmas of all species were wet and showed esterasic activity at pre-anthesis and anthesis stages. Stigmatic surface was continuous with transmitting tissue of glandular nature. Vochysia and Salvertia stigmatic surfaces were formed by multicelular uniseriate hairs, and species of the remaining genera showed papillate surface. The exudate over mature stigmas in all species flowed without rupture of stigmatic surface and pollen tubes grew down between hairs or papillae. Differences on the stigmatic surface agreed with a phylogenetic reconstruction that separated two clades and indicated that Vochysieae is not monophyletic. Stigmatic features could not be associated with pollination and breeding systems.

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Wetzstein, Hazel Y., and S. Edward Law. "Enhanced Visualization of the Fine Structure of the Stigmatic Surface of Citrus using Pre-fixation Washes." Journal of the American Society for Horticultural Science 137, no. 5 (September 2012): 290–93. http://dx.doi.org/10.21273/jashs.137.5.290.

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Stigma characteristics and morphology can be useful in taxonomic and phylogenetic studies, indicate relationships in stigma function and receptivity, and be valuable in evaluating pollen–stigma interactions. Problematic is that in some taxa, copious stigmatic exudate can obscure the fine structural details of the stigmatic surface. Such is the case for Citrus, which has a wet stigma type on which abundant exudate inundates surface papillae. The components of stigmatic surface compounds are highly heterogeneous and include carbohydrates, proteins, lipids, glycoproteins, and phenolic compounds. This study evaluated the efficacy of several pre-fixation wash treatments on removing surface exudate to visualize the underlying stigmatic surface. Wash treatments included various buffer solutions, surfactants, dilute acids/bases, and solvents. Stigmas prepared using conventional fixation methods in glutaraldehyde had considerable accumulations of reticulate surface deposits with stigmatic cells obscured. Pre-fixation washes containing solvents such as methanol, chloroform, and ethanol left accumulations of incompletely removed exudate and crystalline deposits. Alkaline water washes produced a crust-like deposit on stigma surfaces. Buffer washes left residues of plaque-like deposits with perforated areas. In contrast, excellent removal of stigmatic exudate was obtained with a pre-fixation wash composed of 0.2 M Tris buffer, pH 7.2, containing 0.2% Triton X-100 surfactant and allowed clear imaging of the stigma and surface papillae morphology. A central sinus and radially arranged openings on the stigmatic surface were clearly visible and shown for the first time using scanning electron microscopy (SEM).

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Courtial, Johannes, Stephen Oxburgh, and Tomáš Tyc. "Direct stigmatic imaging with curved surfaces." Journal of the Optical Society of America A 32, no. 3 (February 25, 2015): 478. http://dx.doi.org/10.1364/josaa.32.000478.

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Wetzstein, Hazel Y., and Darrell Sparks. "Stigma-Pollen Interactions in Pecan." Journal of the American Society for Horticultural Science 114, no. 2 (March 1989): 355–59. http://dx.doi.org/10.21273/jashs.114.2.355.

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Abstract Early pollen-stigma responses were observed microscopically in controlled pollinations of pecan [Carya illinoensis (Wangenh) C. Koch]. Receptive stigmatic surfaces have rounded, basally attached projecting papillae with an irregularly patterned, noncopious exudate. Polarly flattened pollen, characteristic of grains at anthesis, becomes rounded and hydrated by 1 hr after pollination. Pollen tube emergence is visible within 3 hr of pollination, and extensive pollen tube growth on the stigma is apparent after 8 to 12 hr. Tube growth generally occurs along the stigmatic surface and between adjacent cells. Stigmatic cells collapse after pollen hydration and germination, with collapse extensive 24 hr after pollination. By 48 hr after pollination, stigmatic cells are flattened, and pollen grains and emerged pollen tubes have contents discharged with a similar collapse.

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Cui, Zhouqi, Regan B. Huntley, Neil P. Schultes, Kaleem U. Kakar, Ching-Hong Yang, and Quan Zeng. "Expression of the Type III Secretion System Genes in Epiphytic Erwinia amylovora Cells on Apple Stigmas Benefits Endophytic Infection at the Hypanthium." Molecular Plant-Microbe Interactions® 34, no. 10 (October 2021): 1119–27. http://dx.doi.org/10.1094/mpmi-06-21-0152-r.

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Erwinia amylovora causes fire blight on rosaceous plants. One of the major entry points of E. amylovora into hosts is flowers, where E. amylovora proliferates epiphytically on stigmatic and hypanthium surfaces and, subsequently, causes endophytic infection at the hypanthium. The type III secretion system (T3SS) is an important virulence factor in E. amylovora. Although the role of T3SS during endophytic infection is well characterized, its expression during epiphytic colonization and role in the subsequent infection is less understood. Here, we investigated T3SS gene expression in epiphytic E. amylovora on stigma and hypanthium of apple flowers under different relative humidities (RH). On stigma surfaces, T3SS was expressed in a high percentage of E. amylovora cells, and its expression promoted epiphytic growth. On hypanthium surfaces, however, T3SS was expressed in fewer E. amylovora cells than on the stigma, and displayed no correlation with epiphytic growth, even though T3SS expression is essential for infection. E. amylovora cells grown on stigmatic surfaces and then flushed down to the hypanthium displayed a higher level of T3SS expression than cells grown on the hypanthium surface alone. Furthermore, E. amylovora cells precultured on stigma had a higher potential to infect flowers than E. amylovora cells precultured in a T3SS-repressive medium. This suggests that T3SS induction during the stigmatic epiphytic colonization may be beneficial for subsequent infection. Finally, epiphytic expression of T3SS was influenced by RH. Higher percentage of stigmatic E. amylovora cells expressed T3SS under high RH than under low RH. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

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Zietsman, P. C. "Reproductive biology of Stomatium bolusiae (Aizoaceae: Ruschioideae)." Bothalia 43, no. 1 (January 13, 2013): 23–28. http://dx.doi.org/10.4102/abc.v43i1.83.

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Flowers of Stomatium bolusiae are self-incompatible. The species exhibits crepuscular and nocturnal anthesis, exploiting two different pollination mechanisms. The structure of the hermaphroditic flower appears not to favour cross-pollination. The stigmata are never exposed to pollinating agents, which gain access to the floral rewards by forcing their way between the anthers. Clogging of the stigmatic surfaces by self-pollen is common. Nocturnal anthesis, concomitant with the nocturnal release of attractants and the offering of rewards, indicates that this species is primarily phalaenophilous and secondarily melittophilous, exhibiting a bimodal pollination system.

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Silva-Lora, Alberto, and Rafael Torres. "Explicit Cartesian oval as a superconic surface for stigmatic imaging optical systems with real or virtual source or image." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2235 (March 2020): 20190894. http://dx.doi.org/10.1098/rspa.2019.0894.

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Cartesian ovals, also known as rigorously stigmatic surfaces, are the simplest optical systems capable of producing a perfect point image. Exist both implicit and explicit expressions to represent these surfaces, but they treat both refractive and reflective surfaces independently. Because of the complexity of explicit expressions, the ray-tracing techniques for these surfaces are implemented using third-party software. In this paper, we express Cartesian ovals as a degenerated superconic curve and get a new explicit formulation for Cartesian ovals capable of treating image formation using both object and image points, either real or virtual, and in this formulation can deal with both reflective and refractive rigorously stigmatic surfaces. Finally, using the resultant expressions and the vector Snell–Descartes Law, we propose a self-contained analytical ray-tracing technique for all these surfaces.

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PANDA, SAURIS, and J. J. F. E. DE WILDE. "Diversity and taxonomic value of stigmatic surfaces in Begoniaceae: SEM analysis." Acta Botanica Neerlandica 44, no. 2 (June 1995): 139–50. http://dx.doi.org/10.1111/j.1438-8677.1995.tb00776.x.

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Doskolovich, L. L., D. A. Bykov, G. I. Greisukh, and Y. S. Strelkov. "Design of a stigmatic lens with minimal Fresnel losses." Computer Optics 45, no. 3 (June 2021): 350–55. http://dx.doi.org/10.18287/2412-6179-co-813.

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A method for designing double aspheric lenses enabling minimal Fresnel losses in the class of stigmatic lenses is considered. Minimization of the Fresnel losses is provided by ensuring equal ray-deviation angles on both aspheric surfaces of the lens. The design of the lens is reduced to the integration of an explicit ordinary differential equation. Simple analytical approximations for the lens profiles are also presented.

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Wood, Bruce W. "Flavonoids, Alkali Earth, and Rare Earth Elements Affect Pecan Pollen Germination." HortScience 52, no. 1 (January 2017): 85–88. http://dx.doi.org/10.21273/hortsci11426-16.

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The factors regulating pecan [Carya illinoinensis (Wangenh.) K. Koch] pollen grain germination are poorly understood for both in vitro pollen viability tests and on receptive stigmatic surfaces of pistillate flowers. Potential regulating factors include flavonols, calcium (Ca), Ca-like alkali earth elements (AEEs), and rare earth elements (REEs). When various concentrations of certain naturally occurring simple flavonols (e.g., quercetin, kaempferol, myricetin, naringenin, and hesperetin) were tested in vitro by adding to standard pecan pollen germination medium, hesperetin, myricetin, and kaempferol functioned as a strong agonist at low concentration (0.12–2.0 µm for hesperetin and kaempferol, and 0.25 µm for myricetin), increasing pollen germination 2- to 3.9-fold over flavonol-free media. Hesperetin and myricetin were antagonistic at 16 µm. Kaempferol was not antagonistic at any concentration up to and including 16 µm. Naringenin was an antagonist at concentrations from 0.12 to 16 µm; whereas, quercetin was an antagonist at 8–16 µm, but tended to function as an agonist at low concentration (0.12–0.50 µm). The equal molar replacement of Ca2+ in standard pecan pollen germination media by single REEs, resulted in certain REEs [e.g., yttrium (Y), gadolinium (Gd), and thulium (Tm)] partially replacing the obligate need for Ca2+; thus, functioning as agonists in absence of Ca. All non-Ca AEEs [beryllium (Be), magnesium (Mg), strontium (Sr), expect for barium (Ba)], also partially substituted for Ca2+ at equivalent molar concentrations, but none were as efficacious as Ca2+. Results are suggestive that a) pollen germination in in vitro test can be improved by incorporation of certain flavonols, and b) pollen germination on stigmatic surfaces of flowers in orchards might be influenced or regulated by flavonol composition and Ca-like metals in the liquid matrix of the wet (receptive) stigmatic surface.

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Bellver-Cebreros, C., E. Gomez-Gonzalez, and M. Rodriguez-Danta. "Obtention of meridian caustics and catacaustics by means of stigmatic approximating surfaces." Pure and Applied Optics: Journal of the European Optical Society Part A 3, no. 1 (January 1994): 7–16. http://dx.doi.org/10.1088/0963-9659/3/1/002.

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Ito, Shuto, and Stanislav N. Gorb. "Attachment-based mechanisms underlying capture and release of pollen grains." Journal of The Royal Society Interface 16, no. 157 (August 2019): 20190269. http://dx.doi.org/10.1098/rsif.2019.0269.

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Successful insect pollination can be achieved by a sequence of numerous attachment and detachment events at various biological surfaces. However, the quantitative measurements of pollen adhesion on biological surfaces have been poorly studied so far. We performed atomic force microscopy adhesion measurements of pollen on two most important floral parts for Asteraceae in a course of pollination: the stigma and style of Hypochaeris radicata plant . The results indicated distinct adhesive properties of them—the pollen adhesion on stigmatic surfaces drastically increased over prolonged contact time, while the pollen adhesion increase on stylar surfaces was rather restrained. Based on the observation with cryo-scanning electron microscopy, we explained the experimental results by the presence of morphological features in form of flexible stigmatic papillae that may play a crucial role in enhancing both capillary attraction and van der Waals forces. The distinct adhesive properties seemingly originate from the unique adhesive tasks that each of the floral parts requires to achieve successful pollination. The insights into the adhesive interaction between pollen and the floral parts, obtained in the present study, may lead to better understanding of pollination mechanisms, which are strongly related to our food production. Additionally, the novel pollen adhesive mechanisms learned from the stigma of the studied Asteraceae plant can inspire biomimetic designs of spontaneous gripping systems.

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Wetzstein, Hazel Y. "Stigmatic Surface Degeneration and Inhibition of Pollen Germination with Selected Pesticidal Sprays during Receptivity in Pecan." Journal of the American Society for Horticultural Science 115, no. 4 (July 1990): 656–61. http://dx.doi.org/10.21273/jashs.115.4.656.

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Commercial pesticide formulations of triphenyltin hydroxide, benomyl plus triphenyltin hydroxide, and phosalone completely inhibited pollen germination of pecan [Carya illinoensis Wangenh C. Koch] when incorporated in in vitro germination media at one-fourth to one times the recommended rates. Scanning electron microscopic evaluations of spray effects on receptive stigmatic surfaces showed varying degrees of injury, ranging from minor surface wrinkling with triphenyltin hydroxide to severe collapse and degeneration of stigma papillae with phosalone treatments. Controlled pollinations 1 hour after pesticide sprays resulted in an inhibition of pollen germination and tube growth. Water sprays followed by pollination resulted in normal pollen adherence, hydration, and germination. Chemical names used: methyl[1-[(butylamino)carbonyl]-1H-benzimidazol-2-yl]carbamate (benomyl); S-[(6-chloro-2-oxo-3-(2H)-benzoxazolyl)methyl] 0,0-diethyl phosphorodithioate (phosalone).

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Ioanoviciu, D., C. Cuna, A. Pamula, CI Fatu, and D. Vonica. "Partial pressure gauge proposal based on a stigmatic double focusing mass spectrometer design." Vacuum 43, no. 5-7 (May 1992): 559–62. http://dx.doi.org/10.1016/0042-207x(92)90077-a.

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Schueler, Bruno, and Robert W. Odom. "Applications of Time-OF-Flight Secondary Ion Mass Spectrometry (TOF-SIMS)." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 308–9. http://dx.doi.org/10.1017/s0424820100135149.

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Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides unique capabilities for elemental and molecular compositional analysis of a wide variety of surfaces. This relatively new technique is finding increasing applications in analyses concerned with determining the chemical composition of various polymer surfaces, identifying the composition of organic and inorganic residues on surfaces and the localization of molecular or structurally significant secondary ions signals from biological tissues. TOF-SIMS analyses are typically performed under low primary ion dose (static SIMS) conditions and hence the secondary ions formed often contain significant structural information.This paper will present an overview of current TOF-SIMS instrumentation with particular emphasis on the stigmatic imaging ion microscope developed in the authors’ laboratory. This discussion will be followed by a presentation of several useful applications of the technique for the characterization of polymer surfaces and biological tissues specimens. Particular attention in these applications will focus on how the analytical problem impacts the performance requirements of the mass spectrometer and vice-versa.

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Sakamoto, Naoya, Shoichi Itoh, and Hisayoshi Yurimoto. "Discovery of 17,18O-rich material from meteorite by direct-imaging method using stigmatic-SIMS and 2D ion detector." Applied Surface Science 255, no. 4 (December 2008): 1458–60. http://dx.doi.org/10.1016/j.apsusc.2008.05.052.

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Law, S. Edward, and Harald Scherm. "Electrostatic application of a plant-disease biocontrol agent for prevention of fungal infection through the stigmatic surfaces of blueberry flowers." Journal of Electrostatics 63, no. 5 (May 2005): 399–408. http://dx.doi.org/10.1016/j.elstat.2004.11.008.

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Anderson, Jay F., Hema S. N. Duddu, Steven J. Shirtliffe, and Arthur R. Davis. "Structure of floral nectaries and comparison of reproductive and vestigial organs in the staminate and pistillate flowers of dioecious Silene latifolia (Caryophyllaceae)." Botany 97, no. 1 (January 2019): 1–21. http://dx.doi.org/10.1139/cjb-2018-0120.

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Silene latifolia Poiret of Eurasia has established in North America, prompting this structural study of its mature unisexual buds and flowers. Floral nectaries, anther and stigma changes, and vestigial reproductive structures were studied using light and scanning electron microscopy. In staminate flowers, anthers dehisced before anthesis and >90% of their pollen was liberated within 36 h. Accumulated in the tubular calyx, nectar descended an anthophore from the stomatal-bearing nectary at the stamen bases. Nectary tissue surrounded the pistillode, a central filamentous organ lacking ovules but tipped by hairs resembling stigmatic papillae. In pistillate flowers, nectar flowed into an inflated calyx. The annular nectary had 10 regularly spaced, stomatal-lined craters and was continuous with the adaxial surfaces of the infertile antisepalous and epipetalous staminodes. Key elements of entomophilous pollination leading to successful sexual reproduction of this invasive species include secondary nectar presentation from disparate floral nectaries that, for pistillate flowers, also incorporate the staminodes; rapid pollen release from anthers; and elongation of papillae by tip growth that enhances each stigma’s receptive surface. Context is also provided for future studies of floral nectary development in this model dioecious species.

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Olsen, J. L., S. A. Mehlenbacher, and A. N. Azarenko. "Hazelnut Pollination." HortTechnology 10, no. 1 (January 2000): 113–15. http://dx.doi.org/10.21273/horttech.10.1.113.

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Hazelnuts, (Corylus avellana L.), are wind-pollinated, monoecious, mostly dichogamous, and self-incompatible. About 90% of the cultivars studied are protandrous. Anthesis of the pistillate flower is temperature-dependent and occurs December through February, peaking in January. Stigmatic surfaces may remain receptive for up to 3 months. Four to 5 months separate pollination and fertilization of the ovule; the latter usually occurring between mid-May and the end of June in Oregon. A 10% pollinizer density has been the standard, with a recommended distance of 66 ft (20 m) or less between the main cultivar and the nearest pollinizer. Two or three different pollinizer cultivars, with different times of pollen shed, are recommended. The Oregon hazelnut industry is presently combating the fungal disease, eastern filbert blight, caused by Anisogramma anomala (Peck). Current management recommendations suggest reducing risk of infection are to reduce the most susceptible pollinizer cultivars to a density 5%, then gradually replace those left with immune or more resistant genotypes.

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Correia, Maria Célia Rodrigues, Maria Célia B. Pinheiro, and Heloísa Alves de Lima. "Biologia floral e polinização de Anemopaegma chamberlaynii Bur. & K. Schum. (Bignoniaceae)." Lundiana: International Journal of Biodiversity 7, no. 1 (July 30, 2006): 39–46. http://dx.doi.org/10.35699/2675-5327.2006.22183.

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The present work deals with the floral biology, reproductive system and phenological events of Anemopaegma chamberlaynii Bur. & K. Schum. (Bignoniaceae), in the coastal strand vegetation (restinga) of Maricá RJ., between 1997 and 2000. The flowers display daytime anthesis, are yellow, very attractive, tubulous, hermaphrodite, odoriferous and produce nectar as the floral reward. The nectar is secreted by a nectariferous disk and accumulated in a chamber. The stigmas are bifid, wet and papillous. The stigmatic lobes are receptive to pollen only on the inner surfaces and are sensitive to disturbance. If the stigma is touched but no pollen is deposited, the lobes close and soon reopen. The same occurs when self-pollen is deposited on the receptive surface. However, after manual pollination with cross-pollen the lobes close permanently, enabling to estimate levels of pollination by monitoring stigma closure. Euglossa cordata L., Epicharis dejeanii Lepeletier and E. semiflava Moure are potential pollinators. Xylocopa ordinaria Smith is the primary nectar robber. The species is self-incompatible and has a low fruit set (Fruit/Flower=4.86%). The flowering pattern is the “multiple bang”, showing five episodes per year, with the same intensity, all of them occurring in the most hot and rainy months. Keywords: Anemopaegma chamberlaynii, floral biology, reproduction, restinga, phenology.

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Stockwell, V. O., R. J. McLaughlin, M. D. Henkels, J. E. Loper, D. Sugar, and R. G. Roberts. "Epiphytic Colonization of Pear Stigmas and Hypanthia by Bacteria During Primary Bloom." Phytopathology® 89, no. 12 (December 1999): 1162–68. http://dx.doi.org/10.1094/phyto.1999.89.12.1162.

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Pear blossoms were sampled during various stages of bloom in 1991 and 1992 from orchards at Cashmere, WA, and Corvallis and Medford, OR, for epiphytic populations of culturable bacteria. On stigmatic surfaces, bacteria were isolated from 2 to 32% of blossoms prior to petal expansion and from 47 to 94% of blossoms by petal fall. In general, a lower percentage of hypanthia than stigmas supported bacterial populations. Randomly selected bacteria isolated at population levels of ≥104 CFU/tissue were identified by fatty acid methyl ester analysis. Diverse genera of gram-negative and -positive bacteria were identified from the Medford and Cashmere field sites. Pseudomonas syringae and Pseudomonas viri-diflava were isolated from all sites and were the predominant species detected at Corvallis, where they were isolated from 28% of the blossoms sampled on a given date. Because most pear blossoms do not support detectable populations (≥102 CFU/tissue) of culturable bacteria prior to petal expansion, we speculate that introduced biocontrol agents may become established with minimal competition from indigenous epiphytes at early bloom stages.

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MONNÉ, MIGUEL A., ANTONIO SANTOS-SILVA, and MARCELA L. MONNÉ. "Key to Mexican and Central American genera of Acanthocinini (Coleoptera, Cerambycidae, Lamiinae) with erect setae on elytral surface, excluding the Caribbean Islands." Zootaxa 4885, no. 1 (November 24, 2020): 1–26. http://dx.doi.org/10.11646/zootaxa.4885.1.1.

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A key for identification of the 34 genera of Acanthocinini with erect setae on the elytra occurring in Mexico and Central America (excluding the Caribbean Islands) is provided. Leptrichillus Gilmour, 1960 is synonymized with Lepturgotrichona Gilmour, 1957, and Leptrichillus minutus Gilmour, 1960 is synonymized with Lepturges stigmaticus Bates, 1881 (currently, Lepturgotrichona stigmatica).

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Cady, S. W., and H. C. Wien. "302 POLLINATION AND FRUITSET PATTERNS OF FIELD-GROWN PUMPKINS." HortScience 29, no. 5 (May 1994): 473e—473. http://dx.doi.org/10.21273/hortsci.29.5.473e.

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Investigations of varietal differences in pumpkin flowering and fruitset patterns were initiated in response to reports of poor fruitset by NYS growers. In addition, pollination requirements for marketable fruit were explored in one cultivar. Flowering date, fruitset, and fruit characteristics were recorded for 2 consecutive years in a RCBD of six popular Cucurbita pepo cultivars (Wizard, Happy Jack, Autumn Gold, Ghost Rider, Howden and Baby Bear). On average, female blossoms opened 38 days after 3-wk-old seedlings were transplanted into the field. Flowering period lasted for 3 to 4 weeks. No consistent pattern was found in female flower production nor fruitset until the last week when significant declines occurred. Each blossom only opens for one day and typically closes between 10 am and noon, limiting pollination opportunities. H and-pollination of Wizard' with various dilutions of pollen revealed that a minimum of approximately 2000 grains of pollen is necessary for fruitset. Removal of 66-75% of the stigmatic surfaces did not affect seed number or their location in the fruit, nor fruit shape or size. Fruit size was not correlated with seed number, although no fruit developed with less than 100 seed.

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Olsen, J. L., S. A. Mehlenbacher, and A. N. Azarenko. "Hazelnut Pollination." HortScience 33, no. 3 (June 1998): 555d—555. http://dx.doi.org/10.21273/hortsci.33.3.555d.

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Hazelnuts are wind-pollinated, monoecious, mostly dichogamous, and self-incompatible of the sporophytic type. About 90% of the cultivars studied are protandrous. Anthesis of the pistillate flower is temperature-dependent and occurs from December through February, with its peak in January. Stigmatic surfaces may remain receptive for up to 3 months. Four to 5 months separate pollination and fertilization of the ovule, which usually occurs between mid-May and the end of June in Oregon. A 10% pollinizer density has been the standard, with a recommended distance of <20 m between the main cultivar and the nearest pollinizer. Two or three different pollinizer varieties with different times of pollen shed are recommended. The Oregon hazelnut industry is presently combating the fungal disease, Eastern Filbert Blight, Anisogramma anomala. Part of the current management recommendations are to reduce the susceptible pollinizer varieties to a density of around 5%, and then gradually replace those left with immune or more-resistant genotypes. Recent research by S.A. Mehlenbacher refined methods of using fluorescense microscopy to quickly determine genotype compatibility. The self-incompatiblity is controlled by a single gene with multiple alleles. The biochemical, physiological, and molecular aspects of sporophytic self-incompatiblity are being research by A.N. Azarenko.

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Pusey, P. Lawrence, Virginia O. Stockwell, and Mark Mazzola. "Epiphytic Bacteria and Yeasts on Apple Blossoms and Their Potential as Antagonists of Erwinia amylovora." Phytopathology® 99, no. 5 (May 2009): 571–81. http://dx.doi.org/10.1094/phyto-99-5-0571.

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Apple blossoms were sampled for indigenous epiphytic populations of culturable microorganisms during different stages of bloom at two locations in central Washington State and one site in Corvallis, OR. Frequencies and population sizes of bacteria on stigmas of apple were lower in Washington than at Corvallis, where average relative humidity was higher and possibly favored greater colonization; however, bacteria at Corvallis were mainly pseudomonads, whereas those in Washington were diverse, composed of several genera. In Washington, yeast as well as bacteria were isolated from both stigmatic and hypanthial surfaces. Sampled blossoms were processed immediately to assess microbial populations, or after a 24-h incubation at 28°C and high relative humidity, which broadened the range of detectable taxa evaluated as potential antagonists. Identifications were based on fatty acid methyl ester profiles and rDNA sequence analyses. Yeasts or yeastlike organisms were detected at frequencies similar to or greater than bacteria, particularly in hypanthia. When microbial isolates were tested for their capacity to suppress Erwinia amylovora on stigmas of detached crab apple flowers, many were ineffective. The best antagonists were the bacteria Pantoea agglomerans and Pseudomonas spp. and a few yeasts identified as Cryptococcus spp. Further evaluation of these taxa on flowers could lead to the discovery of additional biocontrol agents for fire blight.

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Wood, Bruce W. "Idiosyncrasies of Pecan Pollination." HortScience 33, no. 3 (June 1998): 555e—556. http://dx.doi.org/10.21273/hortsci.33.3.555e.

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Pecan orchard productivity and yields often suffer due to pollination problems despite copious pollen produced within or near orchards. The problem is most acute in large block-type orchards of one or two varieties and can be due to pollen not being present at time of stigma receptivity or due to selfing. Fruit-set problems do not appear to be due to excessive pollen on stigmatic surfaces, as is the case in walnut. Pistillate flowers set best when pollen is received within about 1 day after becoming receptive. While stigma receptivity appears to lasts several days, pistillate flowers usually fail to complete development if pollinated after ≈2 days. Flowering dichogamy of given varieties varies with tree age and spring temperatures, thus often leading to poor pollination and low fruit-set. Orchards are therefore likely to benefit from the presence of two complementary pollinizers for the main crop variety. Trees in block-type orchards and are beyond about three rows or 50 m from pollinizers are likely to exhibit pollination related yield losses. Many orchards exhibit pollination problems because adherence to the standard two-class Type I/II flowering system often caused planting of noncompatible varieties. A recently developed 30-class Type I/II system allows for greater probability of avoiding pollination problems. Removal of “off-genotype” trees from orchards may reduce yields in block-type orchards.

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Parrie, E. James, and Gregory A. Lang. "Self- and Cross-pollination Affect Stigmatic Pollen Saturation in Blueberry." HortScience 27, no. 10 (October 1992): 1105–7. http://dx.doi.org/10.21273/hortsci.27.10.1105.

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Pollen deposition on the stigmatic surface of blueberry pistils was studied with regard to maximum pollen load and stigmatic fluid production (stigma receptivity). Three hybrid southern highbush cultivars (Vaccinium corymbosum L. with V. darrowi Camp, V. ashei Reade, and/or V. angustfolium Aiton), two northern highbush cultivars (V. corymbosum), and one hybrid half-high cultivar (V. corymbosum with V. angustifolium) were selfand cross-pollinated with counted pollen tetrads until saturation of the stigmatic surface occurred. Stigmatic saturation generally required 200 to 300 tetrads and was characterized by the cessation of stigmatic fluid production and the inability to absorb further tetrads. The loss of stigmatic receptivity was irreversible. Cross-pollination resulted in cessation of stigmatic fluid production at lower levels of tetrad deposition than did self-pollination, suggesting a potential pollen-stigma recognition phenomenon. Northern highbush, half-high, and southern highbush cultivars required 7% to 10%, 12% to 17%, and 14% to 21%, respectively, more self-pollen to develop the stigmatic saturation condition. The potential relation of the pollenstigma phenomenon to self-incompatibility mechanisms is discussed.

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Park, Su-Hyoung, Ki-Taek Kim, Sun-Hyoung Lim, Moo-Kyoung Yoon, Soo-Seong Lee, Changhoo Chun, and Hyo-Geun Park. "Classification and Identification of S-haplotypes Using PCR-RFLP and Measuring the Self-incompatibility Activity in Radish (Raphanus sativus L.)." HortScience 40, no. 4 (July 2005): 1113C—1113. http://dx.doi.org/10.21273/hortsci.40.4.1113c.

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Self-incompatibility (SI) in Brassicaceae vegetables prevents self-pollination by recognizing self-pollens and rejecting them at the stigmatic surfaces. The S-haplotypes of 47 hybrid radish cultivars that are commercially available in Korea were classified and identified using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Twelve kinds of S-haplotypes were identified from the cultivars: S1, S8, S11, S17, S18, S30, and S31 haplotypes in class-I S-haplotype and S4, S5, S13, S21, and S26 haplotypes in class-II S-haplotypes. Even though the class-II S-haplotypes are supposed to exhibit weak and/or leaky SI activity, the class-II S-haplotypes showed the same allele frequency of class-I S-haplotypes in 38 fully classified commercial cultivars. The SI activity was examined using the pollen tube germination test, flower pollination test, and the seed set ratio analysis. The pollen tube test showed low correlation (R2 = 0.13) with the flower pollination test, a conventional method. The results of seed set ratio analysis varied from 0% to 159%, and thus could distinguish the weak and strong SI activity clearly and showed high correlation with the flower pollination test (R2 = 0.69). The seed set ratios of the cultivars possessing the class-I/class-I, class-I/class-II, and class-II/class-II genotypes were 0.6%, 17.4%, and 38.1%, respectively. Among the eight class-II/class-II cultivars, three cultivars showed strong SI activity. The SI activity of the S4S17, S5S8, and S4S26 genotypes varied among cultivars, but the S1S17, S5S17, and S8S26 genotypes showed constant strong, intermediate, and strong activity, respectively, among the cultivars. Results indicate that the SI activity of Brassicaceae vegetables depends not only on the S-haplotypes, but also on the genetic background of cultivars.

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Marcellán, O. N., and E. L. Camadro. "Self- and cross-incompatibility in Asparagus officinalis and Asparagus densiflorus cv. Sprengeri." Canadian Journal of Botany 74, no. 10 (October 1, 1996): 1621–25. http://dx.doi.org/10.1139/b96-196.

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Garden asparagus, Asparagus officinalis L. (off), is dioecious and reproductively isolated from a related ornamental, monoecious Asparagus densifiorus (Kunth) Jessop cv. Sprengeri (spr). Since the latter is a potentially valuable source of germplasm, a study was initiated to identify hybridization barriers. Intra- and inter-specific crosses were made using 32 plants of two commercial cultivars of off and 17 plants of three introductions of spr. Part of the pollinated pistils were fixed and examined via fluorescence microscopy. In some combinations of genotypes, incompatibility reactions were detected: (i) off × off: in the stigmatic tissue, (ii) spr × spr: on the stigmatic surface and in the style, and (iii) spr × off: on the stigmatic surface, in the stigmatic tissue, and in the style. Although pollen tubes reached the ovules in most combinations of genotypes, seeds were only produced in intraspecific crosses. It is concluded that two types of internal barriers are acting: cross-incompatibility at the pollen–stigma and pollen–style levels, and stronger post-stylar barriers that had not been determined yet. Keywords: Asparagus densifiorus cv. Sprengeri, Asparagus officinalis, cross-incompatibility, reproductive isolation.

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Teixeira, Simone de Pádua, Liana Carneiro Capucho, and Sílvia Rodrigues Machado. "Two novel reports of semidry stigmatic surface in Asteraceae." Flora - Morphology, Distribution, Functional Ecology of Plants 206, no. 4 (April 2011): 328–33. http://dx.doi.org/10.1016/j.flora.2010.08.001.

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Silvério, Adriano, and Jorge Ernesto de Araujo Mariath. "The formation of the stigmatic surface in Passiflora elegans (Passifloraceae)." Rodriguésia 61, no. 3 (September 2010): 569–74. http://dx.doi.org/10.1590/2175-7860201061316.

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Abstract The stigma surface is a complex multicellular structure where the development of the pollen tube begins. This development is necessary for sucess in fertilization and depends on recognition processes that involve the anatomy of the stigma. Passiflora is an economically important genus because of its edible fruits. Many authors have described the stigma of Passiflora but nothing is known about the ontogenesis of this structure. This work aimed to describe the formation of the stigmatic surface of Passiflora elegans. Results showed that, in bud, the stigmatic surface of this species is flat with small cells. The cells in the subdermal layer have large vacuoles and the nucleus, near to the external periclinal walls. During its development the stigma surface becomes uneven due to the elongation of cells in the subdermal layer. Elongation results in an increase of external secretory surface area of the stigmas, and probably plays an important role in pollen recognition. The polysaccharide content found in the inner walls of these structures might be involved in the signal process for pollen tube growth during its early development. The morphological evidence presented here shows that, as the stigma of Passiflora is formed by dermal and subdermal cells, it should not be characterized as colleters or papillae and, therefore, it is defined here as stigma emergences.

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Hampson, Cheryl R., Anita Nina Azarenko, and Al Soeldner. "Pollen-Stigma Interactions following Compatible and Incompatible Pollinations in Hazelnut." Journal of the American Society for Horticultural Science 118, no. 6 (November 1993): 814–19. http://dx.doi.org/10.21273/jashs.118.6.814.

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Scanning electron microscopy was used to describe pollen-stigma interactions during compatible and incompatible pollinations of hazelnut (Corylus avellana L.), a species possessing sporophytic self-incompatibility. The stigmatic surface is of the dry type and was covered with elongated, rounded papillae. Compatible and incompatible pollen hydrated within 2 hours of pollination. Compatible pollen tubes emerged by 4 hours and grew into the style by 12 hours after pollination. Penetration of stigmatic papillae appeared to be intracellular in some cases. In incompatible pollinations, however, pollen tube emergence was delayed until at least 8 hours. The pollen tubes were distorted and did not penetrate the stigma.

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Ladd, P. G., I. Nanni, and G. J. Thomson. "Unique Stigmatic Structure in Three Genera of Proteaceae." Australian Journal of Botany 46, no. 4 (1998): 479. http://dx.doi.org/10.1071/bt97038.

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In three closely related genera of the Proteaceae, namely, Lomatia R.Br., Stenocarpus R.Br. and Strangea Meisn. the pollen presenter and stigma at anthesis are covered by specialised cells. The cells are spiral-walled, contain polyphenolic material and are produced from the stigma, and in Lomatia from the pollen presenter. The spiral wall-thickenings are formed on the inside of the primary wall late in the development of the cells when they are budded off from the stigma or presenter surface. Pollen from the anthers is placed onto these cells from where it is taken to other flowers for cross-pollination. The spiral-walled cells prevent contact between self-pollen and the stigma and provide a method whereby cross-pollen can only reach the stigma if self-pollen has been removed. The form of the cells and the mechanism for preventing autogamy is not found in any other plant group.

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Rozier, Frédérique, Lucie Riglet, Chie Kodera, Vincent Bayle, Eléonore Durand, Jonathan Schnabel, Thierry Gaude, and Isabelle Fobis-Loisy. "Live-cell imaging of early events following pollen perception in self-incompatible Arabidopsis thaliana." Journal of Experimental Botany 71, no. 9 (January 14, 2020): 2513–26. http://dx.doi.org/10.1093/jxb/eraa008.

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Abstract Early events occurring at the surface of the female organ are critical for plant reproduction, especially in species with a dry stigma. After landing on the stigmatic papilla cells, the pollen hydrates and germinates a tube, which penetrates the cell wall and grows towards the ovules to convey the male gametes to the embryo sac. In self-incompatible species within the Brassicaceae, these processes are blocked when the stigma encounters an incompatible pollen. Based on the generation of self-incompatible Arabidopsis lines and by setting up a live imaging system, we showed that control of pollen hydration has a central role in pollen selectivity. The faster the pollen pumps water from the papilla during an initial period of 10 min, the faster it germinates. Furthermore, we found that the self-incompatibility barriers act to block the proper hydration of incompatible pollen and, when hydration is promoted by high humidity, an additional control prevents pollen tube penetration into the stigmatic wall. In papilla cells, actin bundles focalize at the contact site with the compatible pollen but not with the incompatible pollen, raising the possibility that stigmatic cells react to the mechanical pressure applied by the invading growing tube.

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35

Giordano, Luiz Carlos da Silva, and Claudia Petean Bove. "Taxonomic considerations and amended description of Humiriastrum spiritu-sancti, Humiriaceae." Rodriguésia 59, no. 1 (January 2008): 151–54. http://dx.doi.org/10.1590/2175-7860200859109.

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ABSTRACT An amended description of Humiriastrum spiritu-sancti is presented, highlighting characters of the ovary, style, stigmatic surface, intrastaminal disk and fruit, alongside with the analysis of the pollen morphology. The species is illustrated and several new records increase the extent of its distribution.

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Salomón, Luciana, Marcelo Paulo Hernández, Daniel Alejandro Giugliano, and Susana Edith Freire. "Floral Microcharacters in South American species of Senecio s.str. (Asteraceae) with considerations on the circumscription of this genus." Phytotaxa 244, no. 1 (January 15, 2016): 1. http://dx.doi.org/10.11646/phytotaxa.244.1.1.

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Senecio L. s.str. is the largest genus in the tribe Senecioneae (Asteraceae) and it has been commonly characterized by its truncate, penicillate stylar tips, separated stigmatic lines, and stamens usually with ecaudate anther bases and balusterform filament collar. A micromorphological study was carried out to determine if South American species of Senecio s.str. present these diagnostic micromorphological characters, as a contribution towards a circumscription of this genus supported by morphology. The study included 72 South American Senecio species from eight sections and 16 series, as well as species from six other genera of subtribe Senecioninae (Delairea, Dendrophorbium, Dendrosenecio, Graphistylis, Lomanthus, Pentacalia), three genera of subtribe Tussilagininae (Aequatorium, Nordenstamia, Roldana), and one of subtribe Brachyglottidinae (Acrisione). The studied characters include: style branches (stigmatic surface, and apices), anthers (filament collar, bases, and appendages), as well as pollen features (shape, size, and sculpture). Analyses of these characters suggested that Senecio s.str. can be defined only by the presence of balusterform filament collars, which are present in 61 out of the 72 studied Senecio s.str. species (vs. cylindrical collar in remaining species). The genera Graphistylis and Delairea also show this trait, however, Graphistylis presents some microcharacters (e.g. “banded” stigmatic surface) that are rather infrequently found in Senecio s.str. Senecio grandis showed cylindrical collars and sagittate anther bases and should be excluded from the genus. The other microcharacters analyzed appeared to be taxonomically uninformative, since their predominant states were found in Senecio s.str. as well as in other genera of Senecioneae.

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Wien, H. Chris, and Dale Riggs. "Pollination and Fruit Set of Pumpkins in Growers' Fields in New York's Capital District." HortScience 32, no. 3 (June 1997): 462D—462. http://dx.doi.org/10.21273/hortsci.32.3.462d.

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Reports of sharply reduced feral bee populations (Apis mellifera) due to harsh winters and prevalence of several bee diseases have raised concerns that pollination and fruit set in pumpkin fields will be adversely affected. In 1995 and 1996, five and eight pumpkin (Cucurbita pepo) fields, respectively, were inventoried on three occasions per season for pollinator activity and percent fruit set. Pollen removal from male flowers was determined visually using a rating scale, while deposition of pollen on stigmata of female flowers was judged by rating fluorescence of pollen on the stigmatic surface under a “black light.” Samples were taken from 15 to 30 locations in each field, and female flowers tagged. These were considered set if they had enlarged to fist size within 14 days. In both years, the amount of pollen remaining on male flowers was negatively correlated with female flower fluorescence ratings. Neither pollen on male flowers nor stigma fluorescence were significantly correlated with percent fruit set. Fifty-two percent of tagged flowers set fruit in both years, with a range of 24% to 84%, and 17% to 78% in 1995 and 1996, respectively. Presence of bee hives in or near the fields had no effect on fruit set. The results indicate that the pollen removal and deposition ratings used were not reliable for predicting fruit set in farmers' fields. In these 2 years, bee hives were not needed in the sampled fields.

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YI, W. "Fungicide Sprays Can Injure the Stigmatic Surface During Receptivity in Almond Flowers." Annals of Botany 91, no. 3 (December 19, 2002): 335–41. http://dx.doi.org/10.1093/aob/mcg019.

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Shimizu-Yumoto, Hiroko, and Kazuo Ichimura. "Senescence of Eustoma Flowers as Affected by Pollinated Area of the Stigmatic Surface." Journal of the Japanese Society for Horticultural Science 75, no. 1 (2006): 66–71. http://dx.doi.org/10.2503/jjshs.75.66.

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Luu, D. T., P. Heizmann, C. Dumas, M. Trick, and M. Cappadocia. "Involvement of SLR1 genes in pollen adhesion to the stigmatic surface in Brassicaceae." Sexual Plant Reproduction 10, no. 4 (August 25, 1997): 227–35. http://dx.doi.org/10.1007/s004970050091.

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Winsor, James A., and Andrew G. Stephenson. "Demographics of pollen tube growth in Cucurbita pepo." Canadian Journal of Botany 73, no. 4 (April 1, 1995): 583–89. http://dx.doi.org/10.1139/b95-061.

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Pollen tube growth rates and pollen tube attrition were examined in Cucurbita pepo plants grown in an experimental garden. Two separate studies were performed utilizing controlled hand-pollinations. First, female flowers were hand-pollinated and collected at intervals over a 22-h period. Examination of stained pollen tubes in these pistils under reflected UV light revealed variation in growth rate: after approximately 7 h, the fastest growing pollen tubes grew at nearly twice the rate of the mass of the pollen tubes. The faster growing tubes reached the top of the ovary well ahead of most of the pollen tubes. Second, density of pollen application was varied and counts of germinated pollen and pollen tubes were made at four points from the stigmatic surface to the receptacle. Attrition was high for all pollen densities, but significantly higher rates occurred at high and medium densities just below the stigmatic surface. Pollen tube attrition at other points in the pistil was associated with constrictions in the stylar tissue and possibly with levels of nutrients in the pistil. Key words: Cucurbita pepo, pollen competition, pollen tube attrition.

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Leitão, Carlos André E., and Angelo L. Cortelazzo. "Structure and histochemistry of the stigmatic and transmitting tissues of Rodriguezia venusta (Orchidaceae) during flower development." Australian Journal of Botany 58, no. 3 (2010): 233. http://dx.doi.org/10.1071/bt09178.

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Stigma and transmitting tissue are floral structures essential for sexual reproduction of angiosperms and can be useful features in taxonomic studies. Rodriguezia venusta (Lindl.) Rchb. f. is an epiphytic orchid belonging to the large subfamily Epidendroideae. The present study describes the structure and histochemistry of the stigmatic and transmitting tissues of R. venusta during flower development. The differentiation and the secretory activity of the stigmatic and transmitting tissues are already visible in the initial stages of development of the flower bud studied. These tissues, which have a reticulated appearance, predominantly secrete mucilaginous material that is accumulated in the intercellular spaces. The stigma is covered by a cuticle that extends over the internal surface of the central canal in the transmitting tissue in this apical portion. In the stigma, the cuticle appears to have micropores, and in the intercellular spaces, there are small spherical bodies that stain for lipids, proteins and total carbohydrates. The functions of these bodies still remain unknown.

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Pansarin, Ludmila Mickeliunas, Emerson Ricardo Pansarin, and Marlies Sazima. "Facultative autogamy in Cyrtopodium polyphyllum (Orchidaceae) through a rain-assisted pollination mechanism." Australian Journal of Botany 56, no. 4 (2008): 363. http://dx.doi.org/10.1071/bt07135.

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Cyrtopodium includes ~42 species, among which is Cyrtopodium polyphyllum (Vell.) Pabst ex F. Barros that occurs in a rainforest in south-eastern Brazil. Its non-rewarding flowers, which attract Centridini bees by deceit, are rain-assisted self-pollinated, a phenomenon rarely found in orchids and other plant families. In addition, self-pollination has never been reported in Cyrtopodiinae and data on the pollination of South American orchids are scarce. Flowers were observed at different times of the day, on both sunny and rainy days, to record floral morphology, visitors and the effects of rainfall on flowers. On rainy days, water accumulates on the stigma and dissolves the adhesive substance of the stigmatic surface. A viscous drop thus forms, which contacts the pollinarium. When evaporation makes the viscous drop shrink, the drop moves the pollinarium with the anther onto the stigmatic surface and promotes self-pollination. Fruit set in natural habitat was low, with 2.4% at one study site, where a similar value (2.2%) was recorded in flowers self-pollinated by rain. In C. polyphyllum, facultative self-pollination assisted by rain is thus an important strategy that guarantees fruit set when pollinator’s visits are scarce, which is common in species pollinated by deceit.

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Buszard, Deborah, and W. W. Schwabe. "Effect of Previous Crop Load on Stigmatic Morphology of Apple Flowers." Journal of the American Society for Horticultural Science 120, no. 4 (July 1995): 566–70. http://dx.doi.org/10.21273/jashs.120.4.566.

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`Cox's Orange Pippin' apple (Pyrus domestics Berth.) trees, which were previously heavily cropped compared to previously defruited trees, had smaller flowers, lower initial fruit set, and a shorter effective pollination period (EPP) than defruited trees. The morphology of apple flower styles and stigmas was studied using scanning and transmission electron microscopy. Virgin stigmas from previously unstressed trees had fully expanded papillae, but 7 days after pollination the papillae were collapsed and distinct pollen tubes penetrated the stigmatic surface. Virgin stigmas from flowers of previously heavily cropped trees were smaller than those from previously defruited trees. The virgin stigmas of the flowers of heavily cropped trees showed collapsed papillae, and differences were observed in the intercellular material in the subtending transmitting tissue. These differences may explain the poor fruit setting characteristics of apple flowers on trees that have borne a heavy crop in the previous year.

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Kowalkowska, Agnieszka K., and Hanna B. Margońska. "Notes on the self-pollination in Dendrobium biflorum (Orchidales, Dendrobiinae)." Acta Societatis Botanicorum Poloniae 81, no. 3 (2012): 223–28. http://dx.doi.org/10.5586/asbp.2012.024.

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The conditions favouring self-pollination are determined for a species of Dendrobium Sw. A survey of gynostemium micromorphology in collected flowers of Dendrobium biflorum revealed two stages of a unique form of autogamy: on germination of pollen tetrads, pollen tubes reached the stigmatic region without the pollen being displaced from the anther locules. This is the first time for this type of autogamy to be reported in Dendrobium biflorum. Pollen grains germinated directly from the locules, bypassing the stigma or falling or sliding down onto the stigmatic surface. The pollen tubes were long and reached the stylar canal. On The Society Islands, differences in exposure of the habitats to weather conditions and altitude gradients influence both composition and form of the vegetation, as well as the occurrence of pollinators. The form of autogamy described here may be the usual method of pollination found on The Society Islands (and even the whole of French Polynesia), where suitable pollinators are absent and/or growth conditions stressful.

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46

Zuberi, M. I., and H. G. Dickinson. "Pollen-stigma interaction in Brassica. III. Hydration of the pollen grains." Journal of Cell Science 76, no. 1 (June 1, 1985): 321–36. http://dx.doi.org/10.1242/jcs.76.1.321.

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A method is described by which the changes in shape that accompany hydration of Brassica pollen grains may be rapidly measured. Using this technique it has proved possible to chart the small amount of hydration that takes place on anthesis, in addition to the response of pollen to a range of relative humidities in vitro and in vivo. Such measurements, together with pollen transfer experiments, indicate that under normal field conditions self-pollen undergoes a brief period of hydration followed by some loss of water and that, in the course of this hydration, many pollen grains are inhibited from further growth. Raised levels of atmospheric water cause a variety of responses in self-pollen, ranging from tube growth through the pistil to the ovary, to tubes inhibited at the stigmatic surface, accompanied by the formation of callose. Surprisingly, compatible cross-pollen is also affected by high humidity, often developing extended tubes that are incapable of penetrating the stigmatic cuticle. The development of stigmatic callose is also stimulated by these tubes, as also occurs when other members of the Cruciferae are induced to germinate on Brassica stigmas by high levels of atmospheric water. This formation of callose in response to challenge by all types of pollen tube suggests models for the self-incompatibility response in Brassica that involve a direct linkage between S (incompatibility) gene products and the formation of callose may require some reexamination. Close study of the operation of the self-incompatibility system in a number of individuals has revealed all aspects of the response to be heavily dependent on the particular S genes possessed by the plant.

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Ayres, T. R. "Thermal bifurcation as a driver of stellar surface inhomogeneities It's Probably Not Too Important, But Read On!" Symposium - International Astronomical Union 176 (1996): 371–84. http://dx.doi.org/10.1017/s0074180900083388.

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Cool gas in the heart of the hot solar chromosphere betrays itself through anomalously strong absorptions of 4.7 μm CO lines at the extreme limb, and off-limb emissions. The origin of the “cool clouds” is thought to be a thermal instability driven by the CO itself. Questions concerning the pervasiveness and detailed structure of the “thermally-bifurcated” zones are being addressed through stigmatic spectroscopy of the solar CO bands with the NSO McMath-Pierce telescope. Here, I report recent progress, and implications for surface thermal inhomogeneities on other stars.

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Kon, Thomas M., Melanie A. Schupp, Hans E. Winzeler, and James R. Schupp. "Screening Thermal Shock as an Apple Blossom Thinning Method. I. Stigmatic Receptivity, Pollen Tube Growth, and Leaf Injury in Response to Temperature and Timing of Thermal Shock." HortScience 55, no. 5 (May 2020): 625–31. http://dx.doi.org/10.21273/hortsci14615-19.

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The use of short-duration applications of thermal energy (thermal shock; TS) as an apple blossom thinning strategy was investigated. Effects of TS temperature and timing on stigmatic receptivity, pollen tube growth in vivo, and visible leaf injury were evaluated in multiple experiments on ‘Crimson Gala’. TS treatments were applied to blossoms and spur leaves using a variable temperature heat gun. TS temperatures ≥86 °C had a strong inhibitory effect on pollen tube growth on the stigmatic surface and in the style. TS temperatures >79 °C reduced average pollen tube length to less than the average style length. Timing of TS treatment (0 or 24 hours after pollination) was not an influential factor, indicating that effective TS temperatures reduced pollen tube growth up to 24 hours after the pollination event. The onset of thermal injury to vegetative tissues occurred at similar TS temperatures that inhibited pollen tube growth in vivo. Excessive leaf injury (>33%) was observed at 95 °C, suggesting relatively narrow differences in thermal sensitivity between reproductive and vegetative tissues. Inconsistent TS temperatures and/or responses were observed in some experiments. Ambient air temperature may have influenced heat gun output temperatures and/or plant susceptibility. While results suggest some promise, additional work is required to validate and further develop this concept.

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Jusaitis, Manfred. "Floral Development and Breeding System of Swainsona formosa (Leguminosae)." HortScience 29, no. 2 (February 1994): 117–19. http://dx.doi.org/10.21273/hortsci.29.2.117.

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Flowers of Swainsona formosa (G. Don) J. Thompson (syn. Clianthus formosus) developed through seven floral stages from buds to open flowers in 17 days. Floral stages were correlated with the sigmoidal growth pattern of the peduncle. Self-pollination was prevented in the species by the presence of a stigmatic cuticle that precluded pollen germination until ruptured, exposing the receptive surface below. Cuticular rupture occurred in nature during bird-pollination and was emulated manually by lightly rubbing a pollen-covered finger across the stigma. The species was self-compatible, and to ensure cross-fertilization when breeding, emasculation before anther dehiscence was essential.

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Miyajima, Daiichiro. "Pollination and Seed Production in Viola." HortScience 41, no. 3 (June 2006): 633–39. http://dx.doi.org/10.21273/hortsci.41.3.633.

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The seed producing system in viola (Viola ×cornuta) was investigated to improve seed yield and to save labor. In a flower five anthers sequentially dehisced; pollen grains were continuously supplied to the anterior petal, which played a significant role in pollination, throughout the flowering period. Evidence from pollen and ovule number suggests that the species is facultative autogamy. Each flower opened more than 10 days was independent of the success in fertilization and kept seed producing ability during the flower longevity period. Pollen grains also maintained viability during the flower longevity period. Pollinators were indispensable for pollination of viola, but pollination in viola was done by a different mechanism from the typical insect-mediated pollination that sticky pollen grains adhere to the exposed stigmas. Pollen grains, accumulated around the entrance of the stigmatic cavity, entered into the cavity by the movement of pollinators. Although the visitation of pollinators was occasional, solitary bees primarily contributed to the pollination of viola. On the other hand, germination of pollen grains on the stigmatic surface was under 50%. Seed set was much lower than the germination percentage of pollen grains. A viola flower had the ability for additional pollinations and fertilization for some days after the fertilization success in some ovules in the flower. This characteristic suggested that repeated pollination is effective to increase the number of mature seeds in a capsule.

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Journal articles on the topic 'Stigmatic surfaces'

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