scholarly journals Secondary pollen presentation and foral traits of Heliconia psittacorum

2018 ◽  
Vol 24 (4) ◽  
pp. 451-458
Author(s):  
Talita Oliveira Nascimento ◽  
Patricia Campos Silva ◽  
Vivian Loges ◽  
Sandra Mariotto ◽  
Willian Krause ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Temporal Dynamics ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Pollen Deposition ◽  
Pollen Transfer ◽  
Stigma Receptivity ◽  
Secondary Pollen Presentation ◽  
Self Pollination ◽  
Pollen Presentation

The secondary presentation of pollen consists of a foral mechanism where the presentation of pollen occurs in other foral structures in addition to the anther, in order to increase the precision of the dispersion of the pollen by the vectors. This study aims to describe the temporal dynamics of secondary pollen presentation, and morphological and morphometric characteristics in stages of pre- anthesis and anthesis in genotypes of fve natural Heliconia psittacorum populations. For the study of foral morphometry traits of length of the fower, stamen, stigma and height of flament insertion in the petal in bud and fower were measured. The foral morphology of pre-anthesis buds and fowers in anthesis, the presence or absence of characteristics such as herkogamy, region of flament insertion in the petal, region of stylar hairs, and of secondary pollen deposition were evaluated. Treatments of controlled pollinations, self-pollination, geitonogamy, cross-pollination, natural pollination and growth to pollen tube were sampled. Floral herkogamy and pollen transfer to the adhered hairs in the stylar region were clearly observed during anthesis, constituting the frst record of occurrence of secondary pollen presentation in Heliconiaceae. Pollen tube growth was inhibited in the stigmatic, style and basal regions of the pistil. Natural fruiting produced little or no fruit. The positioning of the stamens above the stigma, pollen viability and stigma receptivity during anthesis of H. psittacorum fowers may favor self-pollination. The stylar hairs observed in all H. psittacorum populations’ help in the retention of pollen grains. The low fruiting rate in controlled and natural pollinations suggest that the main propagation form of H. psittacorum in the study areas is based on asexual reproduction.

scholarly journals Electrostatic Processes Underlying Natural and Mechanized Transfer of Pollen

1998 ◽  
Author(s):  
Edward Law ◽  
Samuel Gan-Mor ◽  
Hazel Wetzstein ◽  
Dan Eisikowitch
Keyword(s):  
Electric Fields ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Basic Knowledge ◽  
Pollen Deposition ◽  
Average Charge ◽  
Pollen Transfer ◽  
Transfer Vectors ◽  
Pollination Systems ◽  
Relaxation Characteristics

The project objective was to more fully understand how the motion of pollen grains may be controlled by electrostatic forces, and to develop a reliable mechanized pollination system based upon sound electrostatic and aerodynamic principles. Theoretical and experimental analyses and computer simulation methods which investigated electrostatic aspects of natural pollen transfer by insects found that: a) actively flying honeybees accumulate ~ 23 pC average charge (93 pC max.) which elevates their bodies to ~ 47 V likely by triboelectrification, inducing ~ 10 fC of opposite charge onto nearby pollen grains, and overcoming their typically 0.3-3.9 nN detachment force resulting in non-contact electrostatic pollen transfer across a 5 mm or greater air gap from anther-to-bee, thus providing a theoretical basis for earlier experimental observations and "buzz pollination" events; b) charge-relaxation characteristics measured for flower structural components (viz., 3 ns and 25 ns time constants, respectively, for the stigma-style vs. waxy petal surfaces) ensure them to be electrically appropriate targets for electrodeposition of charged pollen grains but not differing sufficiently to facilitate electrodynamic focusing onto the stigma; c) conventional electrostatic focusing beneficially concentrates pollen-deposition electric fields onto the pistill tip by 3-fold as compared to that onto underlying flower structures; and d) pollen viability is adequately maintained following exposure to particulate charging/management fields exceeding 2 MV/m. Laboratory- and field-scale processes/prototype machines for electrostatic application of pollen were successfully developed to dispense pollen in both a dry-powder phase and in a liquid-carried phase utilizing corona, triboelectric, and induction particulate-charging methods; pollen-charge levels attained (~ 1-10 mC/kg) provide pollen-deposition forces 10-, 77-, and 100-fold greater than gravity, respectively, for such charged pollen grains subjected to a 1 kV/cm electric field. Lab and field evaluations have documented charged vs. ukncharged pollen deposition to be significantly (a = 0.01-0.05) increased by 3.9-5.6 times. Orchard trials showed initial fruit set on branches individually treated with electrostatically applied pollen to typically increase up to ~ 2-fold vs. uncharged pollen applications; however, whole-tree applications have not significantly shown similar levels of benefit and corrective measures continue. Project results thus contribute important basic knowledge and applied electrostatics technology which will provide agriculture with alternative/supplemental mechanized pollination systems as tranditional pollen-transfer vectors are further endangered by natural and man-fade factors.

scholarly journals Elaborated pollen packaging and dispensing mechanism induced by petal architecture from a Papaveraceae species

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7066
Author(s):  
Shanlin Yang ◽  
Guangming Chu ◽  
Xiang Shi ◽  
Shaoming Wang
Keyword(s):  
Mating System ◽  
Pollen Grains ◽  
Middle Lobe ◽  
Mixed Mating ◽  
Pollination Efficiency ◽  
Pollen Transfer ◽  
Mixed Mating System ◽  
Secondary Pollen Presentation ◽  
Pollen Presentation ◽  
Total Pollen

Secondary pollen presentation (SPP) is a reproductive strategy that enhances the efficiency of pollen transfer, which has been explored for more than 200 years, resulting in 10 identified types of SPP. The ephemeral plant Hypecoum erectum L. (Papaveraceae) has an elaborate petal structure. The middle lobe is a key functional organ in SPP. To explore the importance of the middle lobe structure, we measured the flowering process, the curling movement and growth of the middle lobe, pollination characteristics, pollination efficiency, and the mating system in H. erectum in the field. The yellow middle lobe structure had an important role in attracting pollinators. The middle lobes on the inner petals function as a redundant cucullate structure and wrapped about 84% of the total pollen grains as soon as the anthers dehisced. These then grew upward and gradually presented pollen to pollinators via the roll out of the middle lobes. One bee species, Colletes vestitus from Colletidae, was the only effective pollinator of H. erectum. The SPP mechanism increased the efficiency of pollen transfer by C. vestitus. The middle lobes, which wrapped pollen and grew upward, contacted the stigma and provided an advantage for self-pollination and outcrossing by growing upward higher than the corolla. Hypecoum erectum L. has a mixed mating system with selfing and outcrossing. Thus, the SPP mechanism plays a key role during the pollination process and is necessary for improving pollination efficiency and promoting reproductive success.

scholarly journals Flowering Biological Characteristics of Camellia weiningensis Y.K. Li.

HortScience ◽  
2021 ◽  
pp. 1-9
Author(s):  
Hongli Wei ◽  
Chao Gao ◽  
Jie Qiu ◽  
Li Long ◽  
Biao Wang ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Polar View ◽  
Floral Organ ◽  
Biological Characteristics ◽  
Flowering Plant ◽  
Flowering Period ◽  
Stigma Receptivity ◽  
Full Flowering

This study aimed to investigate the flowering biological characteristics, floral organ characteristics, and pollen morphology of Camellia weiningensis Y.K. Li. These features of adult C. weiningensis plants were observed via light microscopy and scanning electron microscopy (SEM). Pollen viability and stigma receptivity were detected using 2,3,5-triphenyltetrazole chloride (TTC) staining and the benzidine–hydrogen peroxide reaction method. C. weiningensis is monoecious, with alternate leaves and glabrous branchlets. Its flowering period lasts 2 to 4 months, and the flowering time of individual plants lasts ≈50 days, with the peak flowering period from the end of February to the middle of March. It is a “centralized flowering” plant that attracts a large number of pollinators. Individual flowers are open for 12 to 13 days, mostly between 1230 and 1630 hr, and include four to six sepals, six to eight petals, ≈106 stamens, an outer ring of ≈24.6-mm-long stamens, an inner ring of ≈13.4-mm-long stamens, one pistil, and nine to 12 ovules. The flowers are light pink. The style is two- to three-lobed and 16.6 mm long, showing a curly “Y” shape. The contact surface of the style is covered with papillary cells and displays abundant secretory fluid and a full shape, facilitating pollen adhesion. The pollen is rhombohedral cone-shaped, and there are germ pores (tremoids). The groove of the germ pore is slender and extends to the two poles (nearly reaching the two poles). The pollen is spherical in equatorial view and trilobate in polar view. The pollen vitality was highest at the full flowering stage, and the stigma receptivity was greatest on days 2 to 3 of flowering. The best concentration of sucrose medium for pollen germination was 100 g/L. The number of pollen grains per anther was ≈2173, and the pollen-to-ovule ratio was 23,034:1. C. weiningensis is cross-pollinated. Seventy-two hours after cross-pollination, the pollen tube reached the base, and a small part entered the ovary. The time when the pollen tube reached the base after pollination was later than that in commonly grown Camellia oleifera. The results of this study might lay an important foundation for the flowering management, pollination time selection, and cross-breeding of C. weiningensis.

scholarly journals An Evaluation of Fertility in Arkansas Primocane-fruiting Blackberries

HortScience ◽  
2010 ◽  
Vol 45 (7) ◽  
pp. 1000-1005 ◽  
Author(s):  
Alisha L. Ruple ◽  
John R. Clark ◽  
M. Elena Garcia
Keyword(s):  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Fruit Set ◽  
Pollen Viability ◽  
Tube Growth ◽  
Stigma Receptivity ◽  
Cross Pollination ◽  
Self Pollination ◽  
Selection Of

Floral fertility of five primocane-fruiting (PF) blackberry (Rubus L. subgenus Rubus Watson) genotypes (‘Prime-Jim’®, APF-31, ‘Prime-Ark® 45’, APF-59, and APF-77) and three floricane-fruiting (FF) genotypes (‘Navaho’, ‘Natchez’, and ‘Ouachita’) were tested under field conditions using floricane flowers with four pollination treatments: undisturbed open-pollinated, emasculated self-pollinated, emasculated and cross-pollinated with pollen from a similar fruiting type (PF × PF or FF × FF), and emasculated and cross-pollinated with pollen from a different fruiting type (PF × FF or FF × PF). During primocane flowering, three pollination treatments (undisturbed open-pollinated, emasculated selfed, and emasculated cross-pollinated) were used to further test the fertility of the five PF genotypes. Significant differences between cross-pollination treatments and self-pollination were seldom noted with more differences seen in ‘Prime-Jim’® than any other genotype. Cross-pollinating primocane flowers on ‘Prime-Jim’® resulted in significantly higher fruit set, drupelet set, and average berry weight compared with self-pollination. Fruit set among genotypes ranged from 68.5 to 96.7%, and drupelet set rating ranged from 4.3 to 6.9 for floricane flowers. For open-pollinated primocane flowers, fruit set ranged from 63.9 to 92.1%, and drupelet set rating ranged from 4.3 to 7.2. The genotypes APF-31, APF-59, and APF-77 showed a marked improvement over ‘Prime-Jim’® in both percent fruit set and drupelet set of floricane and primocane flowers. The results indicated that fertility appears to be sufficient in all the genotypes evaluated and that the later-generation PF genotypes show improvement in fertility over ‘Prime-Jim’®. Pollen viability (using both chemical viability testing and in vitro germination testing), stigma receptivity, and pollen tube growth (using florescence) were evaluated in a controlled environment to determine if any improvements could be noticed when comparing a selection of later-generation PF genotypes (APF-31,' Prime-Ark® 45', APF-59, and APF-77) with ‘Prime-Jim’® and ‘Prime-Jan’®. Genotypes APF-31, APF-59, and APF-77 had significantly more viable pollen and pollen germination than ‘Prime-Jan’®. Stigma receptivity was observed in all genotypes. Pollen tube growth did not appear to be inhibited after self-pollination in any genotype studied, although significantly greater florescence resulting from pollen tube growth was seen after cross-pollination compared with self-pollination for APF-59. There were no significant differences in pollen tube growth between cross- and self-pollination for any other genotype.

scholarly journals Corolla Abscission Triggered by Nectar Robbers Positively Affects Reproduction by Enhancing Self-Pollination in Symphytum officinale (Boraginaceae)

Biology ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 903
Author(s):  
Qin-Zheng Hou ◽  
Nurbiye Ehmet ◽  
Da-Wei Chen ◽  
Tai-Hong Wang ◽  
Yi-Fan Xu ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Pollen Deposition ◽  
Nectar Robbing ◽  
Positive Effects ◽  
Symphytum Officinale ◽  
Self Pollination ◽  
Nectar Robbers ◽  
The Impact

Nectar robbers, which affect plant fitness (directly or indirectly) in different degrees and in different ways, potentially constitute a significant part of mutualistic relationships. While the negative effects of nectar robbing on plant reproductive success have been widely reported, the positive effects remain unknown. The target of our study was to evaluate the effects of nectar robbers on the reproductive success of Symphytum officinale (Boraginaceae). We observed the behavior, species and times of visitors in the field, and we assessed the effect of nectar robbers on corolla abscission rate and time. To test the fitness of corolla abscission, we detected the changes in stigma receptivity, pollen viability, pollen amount and appendage opening size along with the time of flower blossom. The flowering dynamics and floral structure were observed to reveal the mechanism of self-pollination. Finally, pollen deposition seed set rate and fruit set rate were determined to estimate the effect of nectar robbers on reproduction success. We observed 14 species of visitors and 2539 visits in 50 h of observation; 91.7% of them were nectar robbers. The pressure and nectar removal of nectar robbers significantly promoted corolla abscission during a period when pollen grains are viable and the stigma is receptive. In addition, corolla abscission significantly increased the pollen deposition and seed setting rate. Our results demonstrate that nectar robbing contributes to enhancing seed production and positively and indirectly impacts the reproductive success of S. officinale. This mechanism involved the movement of anthers and indirect participation by nectar robbers, which was rarely investigated. Considering the multiple consequences of nectar robbing, understanding the impact of nectar robbers on plant reproduction is essential to comprehend the evolutionary importance of relationships between plants and their visitors.

The mating system of Acrotriche serrulata (Ericaceae)

2010 ◽  
Vol 58 (2) ◽  
pp. 124 ◽  
Author(s):  
Melanie Schneemilch ◽  
Emma Steggles
Keyword(s):  
Mating System ◽  
Pollen Viability ◽  
Seed Viability ◽  
Corolla Tube ◽  
Morphological Features ◽  
Stigma Receptivity ◽  
Pollination Experiments ◽  
Controlled Pollination ◽  
Cross Pollination ◽  
Self Pollination

Controlled pollination experiments were conducted on Acrotriche serrulata R.Br. (Ericaceae) to determine the mating system for this species. Pollen viability and stigma receptivity were investigated to ensure effective timing and sourcing of material for maximum fertilisation. Stigmas were found to be receptive in mature buds, with receptivity maintained while nectar remained within the corolla tube. Germination testing showed that pollen from within mature buds was viable. The mating system of A. serrulata was found to be predominantly outcrossing, with 49.8% of cross-pollinated flowers developing to fruit, compared with 8.7% of self-pollinated flowers. Seed viability did not differ significantly between fruits produced by cross-pollination and those produced by self-pollination, although this may be attributable to low sample sizes available for self-pollinated fruits. These results in combination with morphological features of the flower suggest that a pollinator is required for this species.

scholarly journals 529 Pollen Tube Growth in Stage 2 Pollinated Avocado Flowers

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 486C-486
Author(s):  
Thomas L. Davenport
Keyword(s):  
Pollen Tube ◽  
Pollen Dispersal ◽  
Pollen Tubes ◽  
Persea Americana ◽  
Pollen Deposition ◽  
Direct Proportion ◽  
Egg Apparatus ◽  
Self Pollination ◽  
Potential Success ◽  
Stage 1

Individual avocado (Persea americana Mill.) flowers are perfect, opening two times to display two distinct reproductive stages on consecutive days. Stage 1 focuses on presentation of pistils and Stage 2 on presentation of pollen. The Stage 1 opening offers the greatest opportunity for outcrossing due to the absence of available pollen in that stage. Stage 2 flowers, however, are self-pollinated within flowers in direct proportion to the number of white stigmas present at the time of pollen dispersal. The potential success of these self-pollination events was examined in orchard trees of seven commercial Florida cultivars: Booth 7, Brooks Late, Choquette, Monroe, Simmonds, Tonnage, and Tower 2 and compared with hand-pollinations from complementary cultivars (cross pollination) and from flowers of the same cultivar (close pollination). The furthest advancement of pollen tubes down styles and into the ovaries on their way to the egg apparatus was noted in hundreds of individual flowers 24 and 48 h after pollen deposition on receptive white stigmas of the Stage 2 flowers. Virtually none of the seven cultivars exhibited pollen tubes reaching the egg apparatus by 24 h after deposition. By 48 h, however, pollen tubes had reached the egg apparatus in 25% to 85% of the pollinated flowers, depending upon cultivar. Pollen source was inconsequential. The results demonstrate the success of self-pollination in avocados. It is especially important for cultivars growing in humid climates, which display a high proportion of receptive white stigmas in Stage 2.

scholarly journals Reproductive barriers in cassava: Factors and implications for genetic improvement

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0260576
Author(s):  
Massaine Bandeira e Sousa ◽  
Luciano Rogerio Braatz de Andrade ◽  
Everton Hilo de Souza ◽  
Alfredo Augusto Cunha Alves ◽  
Eder Jorge de Oliveira
Keyword(s):  
Population Structure ◽  
Pollen Tube ◽  
Pollen Tube Growth ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Tube Growth ◽  
Reproductive Barriers ◽  
Fertilization Rates ◽  
Flower Abortion ◽  
Hand Pollination

Cassava breeding is hampered by high flower abortion rates that prevent efficient recombination among promising clones. To better understand the factors causing flower abortion and propose strategies to overcome them, we 1) analyzed the reproductive barriers to intraspecific crossing, 2) evaluated pollen-pistil interactions to maximize hand pollination efficiency, and 3) identified the population structure of elite parental clones. From 2016 to 2018, the abortion and fertilization rates of 5,748 hand crossings involving 91 parents and 157 progenies were estimated. We used 16,300 single nucleotide polymorphism markers to study the parents’ population structure via discriminant analysis of principal components, and three clusters were identified. To test for male and female effects, we used a mixed model in which the environment (month and year) was fixed, while female and male (nested to female) were random effects. Regardless of the population structure, significant parental effects were identified for abortion and fertilization rates, suggesting the existence of reproductive barriers among certain cassava clones. Matching ability between cassava parents was significant for pollen grains that adhered to the stigma surface, germinated pollen grains, and the number of fertilized ovules. Non-additive genetic effects were important to the inheritance of these traits. Pollen viability and pollen-pistil interactions in cross- and self-pollination were also investigated to characterize pollen-stigma compatibility. Various events related to pollen tube growth dynamics indicated fertilization abnormalities. These abnormalities included the reticulated deposition of callose in the pollen tube, pollen tube growth cessation in a specific region of the stylet, and low pollen grain germination rate. Generally, pollen viability and stigma receptivity varied depending on the clone and flowering stage and were lost during flowering. This study provides novel insights into cassava reproduction that can assist in practical crossing and maximize the recombination of contrasting clones.

scholarly journals Viability of pollen grains and stigma receptivity in Desert Rose

2022 ◽  
Vol 28 (1) ◽  
pp. 92-98
Author(s):  
Cristiane Gonçalves Souza ◽  
Sabrina Maihave Barbosa Ramos ◽  
Silvia Nietsche ◽  
Clivia Carolina Fiorilo Possobom ◽  
Elka Fabiana Aparecida Almeida ◽  
...  
Keyword(s):  
Abiotic Factors ◽  
Pollen Viability ◽  
Oxygen Demand ◽  
Pollen Grains ◽  
Floral Biology ◽  
Effect Of Temperature ◽  
In Vitro Germination ◽  
Stigma Receptivity ◽  
Flower Opening

Abstract Adenium obesum (Forssk.) Roem. & Schult., popularly known as desert rose, has become a valuable ornamental plant. In floriculture, the production of hybrids is prioritized. Hence, knowledge on floral biology and sexual reproduction of the target species is fundamental. The objectives of this study were: (1) to test sucrose concentrations and temperatures for in vitro germination of A. obesum pollen grains; (2) to identify the effect of temperature on the viability of A. obesum pollen grains; and (3) to evaluate the viability of pollen grains and stigma receptivity in pre-anthesis, at flower opening, and 72 h post-flower opening in three accessions of A. obesum. A significant relationship between temperatures and sucrose concentrations was observed in the in vitro germination test. The highest percentage of in vitro germination of pollen grains, 39.81%, was observed at an estimated temperature of 26.05 °C. Desert rose accessions maintained in biochemical oxygen demand (BOD) chambers at 30 °C during a 16-h light photoperiod showed faster flowering, and temperatures ≥ 25 °C induced pollen grain viability percentages above 69%. Temperature is one of the most important abiotic factors, influencing mainly in pollen germination, pollen tube growing and in efficiency fertilization. The ICA-wd accession stood out and can be considered a pollen donor in artificial pollination. The stigmas of flowers were receptive from a day before flower opening until three days after. The two parameters presented above, stigma receptivity and pollen viability, allow inferences about the appropriate time for successful pollination and subsequent fertilization in desert roses.

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