scholarly journals Pollination and Seed Production in Viola

HortScience ◽  
2006 ◽  
Vol 41 (3) ◽  
pp. 633-639
Author(s):  
Daiichiro Miyajima
Keyword(s):  
Seed Set ◽  
Pollen Grains ◽  
Germination Percentage ◽  
Fertilization Success ◽  
The Other ◽  
Flowering Period ◽  
Flower Longevity ◽  
Ovule Number ◽  
Germination Of Pollen ◽  
Mature Seeds

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.

scholarly journals Pollen adaptation to ant pollination: a case study from the Proteaceae

2020 ◽  
Vol 126 (3) ◽  
pp. 377-386 ◽  
Author(s):  
Nicola Delnevo ◽  
Eddie J van Etten ◽  
Nicola Clemente ◽  
Luna Fogu ◽  
Evelina Pavarani ◽  
...  
Keyword(s):  
Seed Set ◽  
Germination Rate ◽  
Pollen Grains ◽  
Relative Effect ◽  
The Other ◽  
Pollen Load ◽  
Pollination Services ◽  
Ant Pollination ◽  
Negative Effect ◽  
Floral Visitors

Abstract Background and Aims Ant–plant associations are widely diverse and distributed throughout the world, leading to antagonistic and/or mutualistic interactions. Ant pollination is a rare mutualistic association and reports of ants as effective pollinators are limited to a few studies. Conospermum (Proteaceae) is an insect-pollinated genus well represented in the south-western Australia biodiversity hotspot, and here we aimed to evaluate the role of ants as pollinators of C. undulatum. Methods Pollen germination after contact with several species of ants and bees was tested for C. undulatum and five co-flowering species for comparison. We then sampled the pollen load of floral visitors of C. undulatum to assess whether ants carried a pollen load sufficient to enable pollination. Lastly, we performed exclusion treatments to assess the relative effect of flying- and non-flying-invertebrate floral visitors on the reproduction of C. undulatum. For this, we measured the seed set under different conditions: ants exclusion, flying-insects exclusion and control. Key Results Pollen of C. undulatum, along with the other Conospermum species, had a germination rate after contact with ants of ~80 % which did not differ from the effect of bees; in contrast, the other plant species tested showed a drop in the germination rate to ~10 % following ant treatments. Although ants were generalist visitors, they carried a pollen load with 68–86 % of suitable grains. Moreover, ants significantly contributed to the seed set of C. undulatum. Conclusions Our study highlights the complexity of ant–flower interactions and suggests that generalizations neglecting the importance of ants as pollinators cannot be made. Conospermum undulatum has evolved pollen with resistance to the negative effect of ant secretions on pollen grains, with ants providing effective pollination services to this threatened species.

Certation between euploid and aneuploid pollen grains from a tertiary trisomic of rye, Secale cereale L.

Genome ◽  
1987 ◽  
Vol 29 (2) ◽  
pp. 353-356 ◽  
Author(s):  
J. Janse
Keyword(s):  
Secale Cereale ◽  
Seed Weight ◽  
Genetic Factors ◽  
Seed Set ◽  
Transmission Rate ◽  
Extra Chromosome ◽  
Pollen Grains ◽  
Decisive Role ◽  
Germination Percentage ◽  
Secale Cereale L

Male transmission of the translocated extra chromosome 5R3R was studied in a tertiary trisomic of rye (Secale cereale L.) using two pollination densities. With abundant pollen, male transmission reached 4%. When a mean of four pollen grains were brought on every stigma (restricted pollination), a transmission rate of 20% was obtained. Seed set, mean seed weight, germination percentage, and the percentage of plants finally surviving were lower in the case of restricted pollination. It was concluded that certation between euploid and aneuploid pollen grains plays a decisive role in male transmission of the translocated chromosome. Although it was previously shown that aneuploid microspores have a delayed development, a large proportion must have reached maturity before anthesis. Therefore, genetic factors determining male transmission rate will primarily be expressed during pollen germination and tube growth rather than before anthesis. Key words: rye, tertiary trisomic, euploid pollen grains, aneuploid pollen grains, certation.

scholarly journals Storage of Flowering Dogwood (C. florida) Seed

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 786D-787
Author(s):  
Sandra Reed*
Keyword(s):  
Seed Set ◽  
Control Sample ◽  
Seed Storage ◽  
Germination Percentage ◽  
The Other ◽  
Seedling Vigor ◽  
Germplasm Preservation ◽  
Flowering Dogwood ◽  
Reliable Source ◽  
Percent Germination

Flowering dogwood (Cornus florida) is a popular flowering tree that is a mainstay of the southeastern U.S. nursery industry. Because cultivars of this species are primarily propagated through budding onto seed-propagated rootstock, a reliable source of seeds is needed. Disease- and weather-related problems may sometimes result in a shortage of dogwood seed. The objective of this study was to develop a method of storing dogwood seed that would allow growers to save seed during years in which good flowering and seed set occur for use when insufficient seed is available. Open-pollinated seeds were collected in Fall 1999, dried to 6%, 10%, and 14% moisture, and stored at -20, 5, and 22 °C. After 1, 2 and 3 years of storage, seed was stratified for 3 months and then planted in the greenhouse. Percent germination was compared to that of a subsample of the seed lot that had been stratified and planted following collection in Fall 1999. After 1 year in storage, seed dried to 10% and 14% moisture and stored at 22 °C failed to germinate; germination of the other samples ranged from 55% to 97% of that of the control sample. After 2 or 3 years in storage, all seed stored at 22 °C and the seed dried to 14% moisture and stored at 5 °C failed to germinate. Germination of the remaining samples ranged from 76% to 97% of the control in year 2, and from 72% to 109% in year 3. After 3 years in storage, seed dried to 6% moisture and stored at 5 °C and seed dried to 10% moisture and stored at -20 °C had the highest germination percentage and best seedling vigor. Development of a seed storage method for dogwood will benefit both dogwood producers and germplasm preservation efforts.

scholarly journals Some Unresolved Issues of Measuring the Efficiency of Pollinators: Experimentally Testing and Assessing the Predictive Power of Different Methods

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Ram Chander Sihag
Keyword(s):  
Foraging Behavior ◽  
Seed Set ◽  
Reproductive Potential ◽  
Pollen Grains ◽  
The Other ◽  
Transfer Efficiency ◽  
Optimum Number ◽  
Pollen Transfer ◽  
Pollen Transfer Efficiency ◽  
Northwest India

Knowledge of efficiency of pollinators is valuable in the derivation of (i) the degree of mutualism specialization of a flower visitor in the natural plant communities, (ii) the optimum number of pollinators needed for the maximum pollination in a plant population, and (iii) the pollinator risk assessment in the sustainable agriculture. Earlier researchers used many direct and indirect methods for measuring the pollination efficiency (PE) of flower visitors. However, a great ambiguity exists in the usage of this terminology that necessitated its fresh scrutiny. I tested the available three standard methods afresh to find the efficiency of pollinators. These included comparing the (i) number of pollen grains removed and deposited by the visitors; (ii) seed set resulting from a single and the multiple visits of the visitors; and (iii) “pollen transfer efficiency (PTE)” derived from the foraging behavior and abundances of the visitors. Observations were recorded on the visitors of four plant species in an agroecosystem of Northwest India. These plants represented a wide variety of the floral types across the angiosperms. The first two methods, namely, the “number of pollen grains removed and deposited” and the “seed set resulting from a single and the multiple visits,” were appropriate in finding differences between the efficiency ranks of the pollinators of those flowers where the number of deposited pollen grains was less than the number of ovules in the ovary. However, these two methods completely failed in situations where exactly reverse condition of pollen grains and ovules existed. Thus, these two methods of measuring the PE of visitors had limited approach and lacked a universal application over the entire angiosperm taxa. On the other hand, use of “pollen transfer efficiency”, derived from the foraging behavior and abundance of the visitors, seemed to have an edge over the other two methods as this was helpful in finding differences between the efficiency ranks of the pollinators of plants in all the three situations tested in this study. However, validation of all the three methods through the plant reproductive potential seemed to be an integral confirmatory step for drawing inferences about the efficiency of pollinators.

INFLUENCE OF CYTOPLASM ON SEED SETTING IN ALFALFA

1978 ◽  
Vol 58 (2) ◽  
pp. 341-346 ◽  
Author(s):  
R. MICHAUD ◽  
T. H. BUSBICE
Keyword(s):  
Seed Set ◽  
Pollen Grains ◽  
The Other ◽  
Seed Setting ◽  
Positive Effects ◽  
Male Function ◽  
Reciprocal Differences ◽  
Negative Effect ◽  
Medicago Sativa L ◽  
Partial Hybrid

Differences in cross-fertility were observed when four alfalfa (Medicago sativa L.) clones designated A, B, C, and D were used reciprocally as male or female. The clone C cytoplasm was determined to be the source of these reciprocal differences. Plants with clone C cytoplasm performed poorly as male parents, but normally as female parents. The mode of action of the clone C cytoplasm on the male function was not determined, but it appeared to be different from that which causes incomplete pollen development. Plants containing clone C cytoplasm produced an abundance of normal appearing pollen grains. In general, clone C cytoplasm had a negative effect on seed set, clone A and D cytoplasms had positive effects, and clone B cytoplasm had no effect relative to the other three. Selection among cytoplasms in alfalfa for improved seed set and for use in the production of partial-hybrid varieties was discussed.

scholarly journals Occurrence and Prevention of Delayed Autonomous Selfing in Salvia umbratica (Lamiaceae)

2021 ◽  
Vol 12 ◽  
Author(s):  
Han-Wen Xiao ◽  
Yan-Bo Huang ◽  
Yu-Hang Chang ◽  
Yun Chen ◽  
Richard J. Abbott ◽  
...  
Keyword(s):  
Fruit Set ◽  
Seed Set ◽  
Pollen Limitation ◽  
Pollen Grains ◽  
Flower Longevity ◽  
Plant Resources ◽  
Floral Longevity ◽  
Hand Pollination ◽  
Pollen Vector ◽  
Highly Correlated

Delayed autonomous selfing (DAS) provides reproductive assurance under conditions of pollinator and/or pollen-limitation. Few plant species have been investigated to determine if DAS is terminated when a flower is sufficiently pollinated by a pollen vector, thereby saving plant resources for other purposes. We examined this possibility in bumblebee-pollinated Salvia umbratica. We first showed that DAS resulting in high fruit set (100%) and seed set (>80%) per flower occurred in the absence of insect pollinators by means of style recurvature and was completed in 94% of flowers 72 h after they opened. In contrast, in flowers pollinated immediately after opening, DAS was prevented by corollas dropping away before styles recurve toward the upper thecae. We next showed that hand-pollination of flowers immediately after they opened resulted in high fruit set (100%) and seed set (>80%) when 5–10 pollen grains or more were deposited on their stigmas, whereas fruit set and seed set were reduced to 45.00 and 22.50%, respectively, when pollen loads were reduced to 1–3 pollen grains. Finally, we showed that on average single pollinator visits deposited 26 pollen grains on stigmas of flowers that had just opened, which is more than enough to ensure high fruit and seed set. Our results indicate that flower longevity is highly correlated with the pollinator environment and female fitness of S. umbratica, with extended flower longevity allowing DAS to occur being advantageous when pollinators are absent, while reduced floral longevity and prevention of DAS being favored when flowers are pollinated by pollinators. Thus, flower longevity in S. umbratica varies so as to optimize reproductive output and resource efforts, and is dependent on the availability and effectiveness of pollinators to pollinate flowers.

POLLEN PRODUCTION AND DISSEMINATING PROPERTIES OF TRITICALE RELATIVE TO WHEAT

1972 ◽  
Vol 52 (4) ◽  
pp. 569-574 ◽  
Author(s):  
K. C. YEUNG ◽  
E. N. LARTER
Keyword(s):  
Seed Set ◽  
Marker Gene ◽  
Pollen Grains ◽  
Triticum Aestivum L ◽  
Hybrid Seed Production ◽  
Pollen Production ◽  
Hexaploid Triticale ◽  
Anther Length ◽  
Anther Extrusion ◽  
Wide Range

A study of the pollen production properties of three hexaploid triticale strains (Triticale hexaploide Lart.) showed that their anther length was significantly greater than that of wheat anthers (Triticum aestivum L. em Thell.) and the estimated number of pollen grains per anther ranged from 15,000 to 21,000. In comparison, a total of 8000 grains per anther was estimated for wheat, cult Manitou. Eighty-nine percent anther extrusion occurred in triticale cult Rosner, while Manitou averaged 70% anther extrusion. The period of anthesis of triticale varied according to strain but generally was of longer duration than in Manitou and thereby promoted outcrossing. Using a triticale strain carrying a dominant marker gene, 50% seed-set was obtained at a distance of 12 m leeward of the pollen source; however, a small percentage was still obtained at a distance of 30 m. It would appear from the limited number of triticales used in this study that a wide range of variability exists within this species in its pollen production and disseminating properties. With appropriate selection pressures, strains with an outbreeding habit could be developed for the purpose of hybrid seed production.

scholarly journals Asymbiotic germination of Vanilla planifolia in relation to the timing of seed collection and seed pretreatments

2021 ◽  
Vol 62 (1) ◽  
Author(s):  
Chih-Hsin Yeh ◽  
Kai-Yi Chen ◽  
Yung-I. Lee
Keyword(s):  
Seed Germination ◽  
Seed Development ◽  
Seed Coat ◽  
Germination Percentage ◽  
Vanilla Planifolia ◽  
Outermost Layer ◽  
Seed Collection ◽  
Seed Pretreatment ◽  
Immature Seeds ◽  
Mature Seeds

Abstract Background Vanilla planifolia is an important tropical orchid for production of natural vanilla flavor. Traditionally, V. planifolia is propagated by stem cuttings, which produces identical genotype that are sensitive to virulent pathogens. However, propagation with seed germination of V. planifolia is intricate and unstable because the seed coat is extremely hard with strong hydrophobic nature. A better understanding of seed development, especially the formation of impermeable seed coat would provide insights into seed propagation and conservation of genetic resources of Vanilla. Results We found that soaking mature seeds in 4% sodium hypochlorite solution from 75 to 90 min significantly increased germination. For the culture of immature seeds, the seed collection at 45 days after pollination (DAP) had the highest germination percentage. We then investigated the anatomical features during seed development that associated with the effect of seed pretreatment on raising seed germination percentage. The 45-DAP immature seeds have developed globular embryos and the thickened non-lignified cell wall at the outermost layer of the outer seed coat. Seeds at 60 DAP and subsequent stages germinated poorly. As the seed approached maturity, the cell wall of the outermost layer of the outer seed coat became lignified and finally compressed into a thick envelope at maturity. On toluidine blue O staining, the wall of outer seed coat stained greenish blue, indicating the presence of phenolic compounds. As well, on Nile red staining, a cuticular substance was detected in the surface wall of the embryo proper and the innermost wall of the inner seed coat. Conclusion We report a reliable protocol for seed pretreatment of mature seeds and for immature seeds culture based on a defined time schedule of V. plantifolia seed development. The window for successful germination of culturing immature seed was short. The quick accumulation of lignin, phenolics and/or phytomelanins in the seed coat may seriously inhibit seed germination after 45 DAP. As seeds matured, the thickened and lignified seed coat formed an impermeable envelope surrounding the embryo, which may play an important role in inducing dormancy. Further studies covering different maturity of green capsules are required to understand the optimal seed maturity and germination of seeds.

Aspidistra revoluta, a new species from limestone areas in Chongqing, China

Phytotaxa ◽  
2016 ◽  
Vol 257 (3) ◽  
pp. 280 ◽  
Author(s):  
Hao Zhou ◽  
Si-rong Yi ◽  
Qi Gao ◽  
Jie Huang ◽  
Yu-jing Wei
Keyword(s):  
New Species ◽  
Chromosome Number ◽  
Average Length ◽  
Chromosome Complement ◽  
Pollen Grains ◽  
The Other ◽  
Morphological Comparison ◽  
Chongqing Municipality ◽  
Karyotype Asymmetry ◽  
A New Species

Aspidistra revoluta (Asparagaceae) is described and illustrated as a new species from limestone areas in southern Chongqing Municipality, China. The new species can be distinguished from the other Aspidistra species by its unique umbrella-like pistil with large revolute stigma lobes that bent downwards and touch the base of the perigone. A detailed morphological comparison among A. revoluta, A. nanchuanensis and A. carnosa is provided. The pollen grains of A. revoluta are subspherical and inaperturate, with verrucous exine. The chromosome number is 2n = 38, and the karyotype is formulated as 2n = 22m + 6sm + 10st. The average length of chromosome complement is 4.50 μm, and the karyotype asymmetry indexes A1 and A2 are respectively 0.37±0.03 and 0.49±0.01.

CYTOLOGY OF 2n POLLEN FORMATION IN DIPLOID ALFALFA, MEDICAGO SATIVA

1979 ◽  
Vol 21 (4) ◽  
pp. 525-530 ◽  
Author(s):  
Nicholi Vorsa ◽  
E. T. Bingham
Keyword(s):  
Medicago Sativa ◽  
Seed Set ◽  
Pollen Grains ◽  
Genetic Constitution ◽  
2N Pollen ◽  
Diploid Parent ◽  
2N Gamete ◽  
Medicago Sativa L ◽  
Pollen Formation ◽  
Mother Cells

Four diploid (2x) clones of alfalfa, Medicago sativa L., which produced good seed set when used as male parents in 4x-2x crosses were selected for study. The 2x clones descended from 2x haploids of cultivated 4x alfalfa. Fertility in the 4x-2x cross was due to the production of pollen with the unreduced chromosome number (2n pollen) from the 2x parent. The cytological mechanism of 2n pollen formation was found to be disorientation of spindles at metaphase II in up to 38% of the pollen mother cells. Thus, both n and 2n pollen were produced by all four diploids examined. Normal spindles at metaphase II were oriented such that they defined the poles of a tetrahedron and resulted in normal tetrads in a tetrahedral arrangement. Disoriented spindles were basically parallel to each other and resulted in formation of dyads and occasionally a triad. Dyads developed into two 2n pollen grains; triads developed into one 2n and two n pollen grains. Since both n and 2n pollen grains are produced by the diploids, they can be maintained as diploids or they can be used as male parents in crosses to tetraploids. The genetic constitution of 2n pollen resulting from parallel spindles is similar to that expected after first division restitution of meiosis and much of the heterozygosity of the diploid parent is conserved in the gametes. The 2n gamete mechanism has potential application in germplasm transfer and in maximizing heterozygosity in tetraploid hybrids.

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