Manual Self-pollination Research Articles

Temporal variation in coffee flowering may influence the effects of bee species richness and abundance on coffee production

Accurately estimating the contribution of pollinators to production in crop species is important but could be challenging for species that are widely cultivated. One factor that may influence the pollinator-production relationship across regions is phenology, or the timing of recurring biological events, because crop phenology can be proximately controlled by climatic variables and phenology can affect plant reproductive success. For the economically important crop, coffee (Coffea arabica), at least three aspects of flowering phenology (onset, density and frequency) are influenced by precipitation, which varies across coffee’s cultivated range. Of these aspects of flowering phenology, flower density may particularly impact production in coffee because high-density flowering can severely limit outcrossing which is a major contributor to high yields and larger, high quality beans. We studied the C. arabica coffee plant-pollinator interaction over 3 years and across two distinct types of coffee blooms: (1) low-density, synchronous flowering and (2) high-density, synchronous (mass) flowering. Bee species richness was similar for four out of five flowering periods (9.8 ± 2.7 95% CI), but nearly tripled during one high-density flowering period (26 ± 8.6 95% CI). During low-density flowering coffee fruit set rates were varied, but when coffee flowered at high-density, initial fruit set rates remained close to 60% (the rate obtained from manual self-pollination of coffee flowers in pollination experiments). We discuss how changing precipitation patterns may alter coffee flowering phenology and the coffee plant-pollinator relationship, providing insight into how climate change may influence this interaction as well as the resultant coffee production.

Pollination biology and reproduction of Seemannia sylvatica (Kunth) Hanstein (Gesneriaceae) in the Serra da Bodoquena National Park, Mato Grosso do Sul

In Brazil, the family Gesneriaceae is represented by 23 genera and approximately 200 species. Seemannia sylvatica is an herb that occurs in dense populations in the riverbeds at Serra da Bodoquena. Goals of this study were to report the floral biology (on the first five days of anthesis), as well as to determine the breeding system and the pollinators of S. sylvatica. Data collection was conducted from June 2005 to July 2006 through monthly field trips, lasting for five days. Data on floral biology, breeding system and on the floral visitors were taken from individuals located along a track 2500 m long, in riparian forest of Salobrinha river. Flowers of S. sylvatica are tubular, red, with no perceptive odor and lasted more than five days (ca. 10 - 20 days in individuals transferred to an urban garden and kept in vases). Seemania sylvatica is protandrous, and the male phase occurred between the first and the fourth days of anthesis, while the female one started in the fifth day. Mean nectar volume secreted was 4.77 ± 3.2 µl, with a significative variation among flowers of different ages. Otherwise, nectar concentration average was 9.71 ± 4.41%, and did not varied significantly in flowers of different ages. The flowers of S. sylvatica were pollinated mainly by the hummingbirds Phaethornis pretrei and Thalurania furcata, and pierced by the bee Ceratina chloris. The butterfly Parides anchises orbygnianus was considered an occasional pollinator of these flowers. Seemannia sylvatica is self-compatible, since fruit set occurred on the experiments of spontaneous self-pollination, manual self-pollination, cross-pollination and open pollination (control). The protandry, coupled with the pattern of nectar production, characterized by low volume and solute concentration, which induces the pollinators to visit different flowers in a given circuit foraging, act maximizing the likelihood of cross-pollination in S. sylvatica. Moreover, the high proportion of fruit set by autogamy is an important strategy considering that S. sylvatica is visited by few species, being pollinated mainly by P. pretrei. Therefore, in the absence of these visitors, the formation of fruits may be achieved.

Late-acting self-incompatibility in Acca sellowiana (Myrtaceae)

Acca sellowiana (Berg) Burret is a predominantly allogamous species with hermaphrodite flowers that has barriers to self-fertilisation such as dichogamy by protogyny and self-incompatibility. This study aimed to identify when self-incompatibility occurs in A. sellowiana flowers submitted to self-pollinations. Pollinations were made using nine known self-incompatible accessions in several treatments including manual cross-pollination, manual self-pollination, no pollination and natural pollination. Flowers were pollinated and pistils collected at times ranging from 1 to 30 days after pollination (DAP). In both cross- and self-pollinations the fertilisation occurred from 18 DAP and the zygote was visualised at 24 and 26 DAP, respectively. The abscission of the self-pollinated flowers increased from 26 DAP onwards, when significant differences (P < 0.05) were found for the percentage of abscission among self-pollinated and cross-pollinated flowers. At 30 DAP, 72% of self-pollinated flowers were abscised. The size of ovules and ovaries of self-pollinated flowers showed no significant difference from those of non-pollinated flowers throughout 30 DAP, while those from cross-pollinated flowers were significantly larger (P < 0.05) than the other treatments from 22 and 24 DAP, respectively. After 40 DAP, there was no fruit development in self-pollination and non-pollination treatments. Our study brings greater clarity to the mechanism of self-incompatibility in A. sellowiana, indicating late-acting self-incompatibility occurring through the rejection/abscission of self-pollinated flowers precisely after syngamy and zygote formation.

Biologia reprodutiva de Pyrostegia venusta (Ker-Gawl) Miers (Bignoniaceae) e comportamento de forrageamento dos visitantes florais predominantes

Pyrostegia venusta (Ker-Gawl) Miers is a semiwoody liana of dense foliage, and considerable one of the main plants invading of pastures in the Cerrados. This study aimed at to describe the breeding fenology, to analyze the foraging activity of the floral visitors, and to evaluate the system of predominant breeding in P. venusta in an area of urban-rural bordering zone. Therefere, the flowers characteristics were registered, accomplished pollination controlled tests were, collections of the flowers visitors and studied the behavior of the predominant species. Pyrostegia venusta flowered between April and September. The largest breeding successes occured with geitonogamy (66.7%), cross-pollination (63.3%) and manual self-pollination (36.7%), defining the presence of self-compatibly and necessary of animals pollinators. In the flowers, 1,085 specimens of insects were captured, of which Apis mellifera L., 1758 (Apidae), Camponotus sp.1 (Formicidae), and Trigona spinipes (Fabr. 1793) (Apidae) were the predominant species. It is here suggested that the plant presents ornitofily syndrome, as the hummingbirds Phaethornis eurynome Lesson, 1832 (Phaethornidae) e Hylocharis chrysura Shaw 1812 (Throchilidae) the possible pollinator species of that plant in the studied area.

Study on the mating compatibility of part pear varieties and wild types of Pyrus ussuriensis

To understand the mating compatibility of Pyrus ussuriensis Maxim., we studied the fertility of pollen and conducted a hand-pollination trial in the field on some pear varieties and wild types. The results showed that about 53% of varieties among 32 tested genotypes were male sterile. Not only did the pollen vitalities in normal varieties show distinct differences, but pollen vitalities from flower forcing in a glasshouse were found to be lower than those from natural flowering in the field, which had no apparent effect on fruit setting of tested varieties. Most of the tested genotypes such as Nanguoli, Pingxiangli, and Hanxiangli showed selfincompatibility (SI). Honghuagaili could bear fruit after hand pollination, but there were abnormal seeds in its fruits. So we suggested it was a recessive SI that happened during embryo development. Longxiangli has the capacity of self-compatibility (SC) to some extent, its fruit setting rate of inflorescence could reach 23.3%. Manual self-pollination during bud flowering could improve the fruit setting rate of part tested genotypes with SI, but had no effect on the fruit setting rate 3 days after flowering. Mating between female parents with the variety selected from F1 generation showed that the majority of their combinations were compatible. There was one-way SC when Nanguoli was crossed with Hanhongli, while no fruits could be found after Hanhongli was crossed with Nanguoli. It may be related to the S-genotype or haplotype of Nanguoli. In addition, mating between the varieties derived from bud mutation with the female parent appeared incompatible. We concluded that P. ussuriensis Maxim. is similar to other grown pear systems with the characteristics of SI, the fruit setting rate of self pollination in some varieties and wild types can be improved by artificial self-pollination during bud flowering, and fruit cannot be developed through pollination between the varieties from bud mutation and the female parent.

Ecologia da polinização de Raphiodon echinus (Nees & Mart.) Schauer (Lamiaceae) em Petrolina, PE, Brasil

Raphiodon echinus é uma espécie de hábito rasteiro, que ocorre espontaneamente em áreas de caatinga. No presente trabalho foram observados a biologia reprodutiva desta espécie com o objetivo de contribuir com informações sobre sua ecologia da polinização. As observações foram feitas em áreas de caatinga da Embrapa Semi-Árido, em Petrolina, PE. Para os experimentos de autopolinização espontânea, autopolinização manual, apomixia, geitonogamia, xenogamia, botões foram ensacados, emasculados e polinizados, quando necessário. Flores foram marcadas para estimar a polinização em condições naturais. Os visitantes florais foram observados das 7h30 min às 16h00, totalizando 45 horas de observações. As flores de R. echinus são infundibuliformes, de coloração violeta, exalam odor adocicado e estão reunidas em glomérulos. A antese é diurna, assincrônica, sendo mais freqüente no período da manhã, por volta das 07h00. A duração das flores é de aproximadamente 10 horas e cada inflorescência apresenta número variado de flores/dia. As flores são visitadas por abelhas e borboletas. Centris hyptidis foi responsável por 26% do total das visitas e, de acordo com o comportamento e freqüência de visitas, foi considerada como polinizador efetivo desta espécie. Quanto ao sistema de reprodução, R. echinus é autógama facultativa, produzindo frutos por autopolinização manual (70%), geitonogamia (63%) e xenogamia (40%).

Floral biology ofPilosocereus tuberculatus(Werderm.) Byles & Rowley: a bat pollinated cactus endemic from the “Caatinga” in northeastern Brazil

Brazil is the third major centre of diversity for the family Cactaceae, with approximately ¾ of the species found in the country being endemic, and a total of 162 native species, including around 20 belonging to Pilosocereus. This family is exclusively pollinated by animals, varying widely between beetles, bees, butterflies, moths, hummingbirds and bats. Pilosocereus tuberculatus is a tree-like cactus with candelabriform branching, with a relict distribution restricted to a few localities in the states of Pernambuco, Bahia, Sergipe and probably southern Piauí. The present work reports observations of bat-pollination in natural populations of the species in an area of dryland woody vegetation (‘caatinga’) in the municipality of Buíque, state of Pernambuco, Brazil. The slightly zygomorphic flowers have olive-green outer perianth-segments and white inner perianth-segments with purplish spots, and a straight, almost cylindric flower tube 3.5–4.0 cm long. Nocturnal anthesis, a strong smell and internally white flowers with abundant nectar (23–309µl) of relatively low sugar content (9.5–17.0%) are characteristic of the bat-pollination syndrome. Pollen is available and the stigma is functional during anthesis as a whole, from between 18:00–18:20h and 8:20–8:50h the following morning. Visits were recorded during the day by bees (Apis mellifera, Trigona spinipes and Xylocopa grisescens) and a hummingbird (Heliomaster squamosus) and during the night by bats (Glossophaga soricina and Lonchophylla mordax). The bats were observed at intervals varying between 5 seconds and 55 minutes, during 18 nights (i.e. 270 hours of observation). In P. tuberculatus spontaneous self-pollination did not produce fruits. The ratio of fruits formed by cross-pollination (69%) compared with manual self-pollination (0%) indicates that the predominant reproductive system in P. tuberculatus is allogamy, and that its reproduction depends on the efficiency of the pollen-vectors. Based on behaviour displayed during bat, bee and hummingbird visits, and the ratio of natural fruit formation, P. tuberculatus depends mostly on its nocturnal visitors for pollination. Bat-pollination, which is predominant for the genus Pilosocereus, has been interpreted as a mechanism of parallel evolution between cacti and bats, and it is possible to consider P. tuberculatus as an example of this close relationship, including a the new record of the glossophagine bat L. mordax as a cactophilic bat.

Reduced seed production, inbreeding, and pollen shortage in a small population of a threatened tree, Magnolia stellata

We investigated how genetic factors and pollen shortage affect seed production in a small population of Magnolia stellata, a threatened insect-pollinated tree. We used microsatellite and manual pollination techniques, and compared a small population to a large one. Compared to the large population, the small population showed low allelic variation and had an F IS significantly greater than 0 in adults, indicating that genetic deterioration, including genetic drift and inbreeding, may have occurred in adults. Manual self-pollination lowered seed production relative to manual cross-pollination to a different extent between populations: δ (the magnitude of inbreeding depression due to self-fertilization) was lower in the small population than in the large population. However, under natural pollination, the estimated embryo mortality rates after ovules self-fertilized were similar between the two populations because the primary selfing rate was higher in the small population. The ovule mortality rate due to pollen shortage and that due to factors independent of pollen shortage and selfing were both approximately 10% higher in the small population, suggesting that pollen transfer may have decreased and genetic deterioration effects may have increased in that population. These factors reduced seed production in the small population (female reproductive success = 0.3%) compared to the large population (2.6%). Our results suggest that seed production in the small population of M. stellata is strictly limited by elevated pollen shortage, selfing, and genetic deterioration in adults, which accelerate the risk of extinction.

Reproductive Ecology of Rhynchanthus beesianus W. W. Smith (Zingiberaceae) in South Yunnan, China: A Ginger with Bird Pollination Syndrome

Rhynchanthus beesianus W. W. Smith (Zingiberaceae) is an epiphytic tropical ginger with a very conspicuous floral display, but almost no fruit set under field conditions. The reproductive ecology encompassing phenology, floral biology, and pollination and breeding systems was investigated in an evergreen broad-leaved forest in Yunnan Province, Southwest China. The flowers possess a typical bird pollination syndrome, but no effective pollinators were observed during 138 h of observation. Female Black-breasted Sunbird (Aethopyga saturata) and bumblebees visited R. beesianus regularly, but they all played roles as nectar robbers. No fruit was found in the bagging treatment, and fruit set following manual self-pollination ((57.55 ± 4.08)%) was comparable with cross-pollination ((64.32 ± 4.42)%), suggesting that R. beesianus is self-compatible but spontaneous self-pollination in this species does not occur. Seed set of open-pollination ((26.42 ± 3.11)%) was significantly lower than manual self-pollination ((73.41 ± 4.16)%) and cross-pollination ((75.56 ± 4.52)%), confirming that R. beesianus was dependent on animals for fertilization and suffered a serious pollinator-limitation. (Managing editor: Wei Wang)

A interação entre Cuphea brachiata Koehne (Lythraceae) e seus visitantes florais nas dunas litorâneas de Abaeté, Salvador, Bahia.

The floral biology, flowering behavior and plant breeding system of C. brachiata were investigated in a coastal sand dune ecosystem (12º55’33”S e 38º20’08”W) in Salvador, Bahia state, Northeast Brazil. The behavior of the predominant visiting bees Xylocopa (Neoxylocopa) cearensis Ducke 1910 and Centris (Centris) leprieuri Spinola 1841 was recorded with the aim of identifying their role as potential pollinators. The corolla is yellow, small, zigomorphic and homogamic. Anthesis is diurnal and longevity reaches ca 2 d (n=58); flowering synchrony is low (0.43) at the population level, resulting in a long flowering period. Mean nectar volume for first (2.13 ± 0.93 mL, n=27) and second day (0.96 ± 0.60 mL, n=26) flowers differed significantly (t=5.741, p<0.0001). Nectar concentration was lower in first day flowers (20%) than in second day flowers (26%), probably due to the reduction in volume caused by evaporation. Fruit formation was low in manual self-pollination (7%) and absent for spontaneous self-pollination. The highest percentage of fruit formation (89%) was found in control (natural conditions), suggesting that pollen vectors are important for the reproduction of C. brachiata. X cearensis and C. leprieuri collect nectar by landing on the four lower petals and introduicng their head into the corolla tube. Pollen adheres to the bee’s forehead at the same place that contact the reproductive structures of the flower. X. cearensis is the most efficient pollinator of C. brachiata, considering its local abundance, pattern of foraging activity, frequency of contact with reproductive structures and pollen transport.

Tracking Papaya Pollen Movement with the GUS Transgene Marker

Genetically engineered (GE), virus-resistant papaya cultivars in Hawaii are easily identified by a colorimetric assay for the β-glucuronidase (GUS) marker transgene. We used GUS to track pollen movement from a central 1-acre plot of gynodioecious GE `Rainbow' plants into seeds on surrounding border rows of non-GE `Sunrise' papaya. GUS evidence of cross-pollination occurred in 70% of female plants (43% of assayed seeds), compared with only 13% of the predominantly self-pollinating hermaphrodite plants (7% of seeds) segregating in the gynodioecious `Sunrise' border rows. The percentage of GUS+ seeds in border row plants showed a weak negative correlation (r = –0.32) with distance from the nearest GE tree (30 m maximum). In a non-GE papaya field located less than a mile downwind from the `Rainbow' source, no evidence of GUS was found in 1000 assayed seeds. In a separate study, the origin of GUS+ seed discovered in papaya fruits from an organic farm was investigated. Leaf GUS assays revealed that 70% of trees were GE, indicating that the grower had planted GE seed. The impact of pollen drift from GE trees in the same field was determined by screening seed samples from 20 non-GE hermaphrodites for GUS expression. Only three hermaphrodites (15%) showed GUS+ seeds, at low levels ranging from 3% to 6% of contaminated samples. These data indicate that the major source of GE contamination in organic fields is seeds of unverified origin, rather than pollen drift from neighboring GE fields. Organic growers are advised to: 1) plant only seed that is known to be non-GE, preferably obtained by manual self-pollination of selected non-GE hermaphrodites; 2) avoid open-pollinated seed; and 3) grow only hermaphrodite (self-pollinating) trees, removing any female or male plants from production fields.

Reproductive biology of Butea monosperma (Fabaceae).

The reproductive biology encompassing phenology, floral biology, pollination and breeding systems, of Butea monosperma, a beautiful tree of the Indian subcontinent, was investigated in a protected dry, deciduous forest located in New Delhi. Phenological studies indicated that although the species shows a regular flowering season, all trees do not flower every year. Flowers are typically papilionaceous; the stigma is wet papillate and the style is hollow. The flowers show characteristics of bird pollination being large and bright orange-red in colour with copious amounts of nectar, and exhibiting diurnal anthesis. Although the flowers are frequented by as many as seven species of birds belonging to six families, only one species, the purple sunbird (Nectarinia asiatica), is the effective pollinator. The flowers are also pollinated by the three-striped squirrel (Funambulus tristiatus). Unlike other flower visitors, these two pollinators forage the nectar from the open side of the keel (legitimate path) during which pollen grains are deposited on their body parts. After the first visit of a sunbird or a squirrel, virgin flowers showed pollen load on the stigma and developed into fruits. B. monosperma shows a weak form of self-incompatibility. Fruit set following manual self-pollination (5.25 %) was comparable with open-pollination (approx. 5 %) but was significantly lower than manual cross-pollination (22.51 %). This indicates that there is a high degree of geitonogamous pollination in this species, which may lead to a weakening of self-incompatibility as a means of reproductive assurance. The results are analysed in the light of prevailing discussions on specialized vs. generalized pollination systems.

Pollination of Angelonia cornigera Hook. (Scrophulariaceae) by Long‐Legged, Oil‐Collecting Bees in NE Brazil

Abstract: The pollination of Angelonia cornigera Hook. (Scrophulariaceae) was studied in Caatinga vegetation, in the municipality of Buíque, Pernambuco state, northeastern Brazil. The plant is a perennial of open areas. Up to 60 flowers are produced in terminal, leafy racemes. The flowers are violet, strongly zygomorphic, of gullet type, with a pair of posterior pockets. Each pocket contains a patch of oil‐producing glandular hairs (elaiophore). The flowers were only visited, and pollinated, by oil‐collecting female bees of the Apidae‐Apinae: Centris hyptidis and Tapinotaspis spec. nov. 1. These two bees differ considerably in size but they share the peculiarity of possessing one pair of disproportionately elongate legs suitable to gain access to the concealed elaiophores. In C. hyptidis, it is the front pair, whereas in T. spec. nov. 1 the mid pair of legs is elongated. T. spec. nov. 1 exhibited two modes of visiting behaviour. Angelonia cornigera is self‐incompatible; it does not set fruits from spontaneous or manual self‐pollination. This is the fifth observed species of the genus Angelonia whose flowers are adapted to oil‐collecting bees in the Caatinga formation. Its flowers deviate in several aspects from the other studied Angelonia spp. regarding pollination relationships. New data on A. hirta and A. tomentosa are appended.

Mating systems in two species ofPotentilla from Alaska

Aspects of reproductive ecology have been studied in two species ofPotentilla (Rosaceae) from interior Alaska. Data were collected to determine mating system traits such as seed: ovule and pollen: ovule ratios, and experiments were carried out in the field in order to study the effect of caging, emasculation, and manual self-pollination on seed set and seed quality. Mating system strategies differ between the two species in the populations examined. High pollen: ovule ratio, high seed: ovule ratio, good autodeposition ability, and unpredictable pollination in concert with self-incompatibility indicate thatP. hookeriana in the population studied has adopted a more or less pseudogamous mating system. In contrast, the data suggest thatP. uniflora in the studied population is approaching a sexual, facultatively outbreeding species. Because both species exhibit ploidy variation, a trait common among agamospermous plants, it is concluded that both species are likely to be facultatively agamospermous but that sexual reproduction is much more important in the population ofP. uniflora than it is inP. hookeriana.

Independence of self-compatibility and potentiality for self-pollination in peach x almond hybrids

The almond of commerce (Prunus dulcis (Mill.) D.A. Webb) is self-incompatible (SI) and requires honey-bees to effect the transfer of pollen among cultivars that flower simultaneously. Four year old trees from the F2 generation of several peach x almond hybrids were studied to determine whether self-compatibility (SC) and the potentiality for natural, i.e., abiotic, self pollination (NSP) are genetically related or are inherited independently. Both SC and the high potentiality for NSP are characteristic of peach (Prunus persica (L.) Batsch) but not almond. Forty percent of SC genotypes exhibited adequate NSP (SC, +NSP) for good fertility i.e., without insect-mediated pollination. The remaining 60% of SC genotypes (SC,-NSP) exhibited an average 61% reduction in fruit set on limbs bagged to exclude honeybees during anthesis relative to fruit set on open pollinated limbs. Our data are consistent with the concept that fertility is dependent upon the load of compatible pollen deposited on the stigma. Fruit set reduction on bagged limbs, compared with bagged and self-pollinated limbs, was presumably due to a) lack of/insufficient pollination for fertilization and/or b) post-zygotic abortion of genetically inferior recombinants. Selection following manual self-pollination may result in SC genotypes with or without the capacity for NSP. In contrast, significant fruit set on limbs enclosed during pistil receptivity necessitates that the genotype selected express both SC and the potentiality for NSP.