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Globally, agricultural crops are often dependent on insect pollination. Blueberries are an example of such a crop and owing to their proposed health benefits they are grown around the world, including locations where their native bumble bee pollinators do not occur. In the absence of bumble bees, blueberry pollination in South Africa and many other parts of the non-native, commercial range is performed primarily by honey bees. Despite this, the effectiveness of honey bee pollination on blueberries remains understudied. This study determined the effect of honey bee pollination on components of fruit yield (fruit set and mass) of five blueberry varieties that are extensively planted in South Africa. For each variety, two metrics were calculated: 1) the benefit of bees — a comparison of fruit yields after exposure to honey bees and fruit yields after honey bee exclusion, 2) the pollination deficit — the difference in yield between hand pollination (maximum yield potential) and yields after exposure to honey bee pollinators. Honey bee pollination consistently resulted in improved yields, although the magnitude of this improvement (i.e., the benefit of bees) was dependent on the variety considered. Similarly, the pollination deficit also varied considerably across varieties and while some varieties appeared to perform close to maximum potential (small pollination deficit), others yielded well below their maximum potential under honey bee pollination. This study demonstrates that honey bees are functional pollinators of blueberries in areas where native blueberry pollinators are absent. However, in such areas, it is important that special focus be given to selecting blueberry varieties that perform well with honey bees as their sole pollinator. Further research is necessary to determine how the pollination deficit of blueberry varieties can be decreased as well as how to increase the effectiveness of honey bee pollination.

Global pollinator declines and land-use change can lead to pollination limitation with implications for agricultural productivity. Hand pollination is used in agricultural production as a technique to manually pollinate crops. But the prevalence of hand pollination, as well as benefits and costs, remain unknown. We systematically reviewed the literature for examples, methods, drivers, and economic motivations of hand pollination. Furthermore, we discuss the risks, constraints, and opportunities of hand pollination. We found evidence for 20 hand-pollinated crops, including minor but also economically important crops (e.g. apple, oil palm, cacao). The lack of pollinators was the most important reason for the application of hand pollination (50% of crops), while insufficient proportion or proximity of pollinizers (8% of crops) and skewed sex ratio or dichogamy (8% of crops) were second most important. The main economic motivations for practicing or recommending hand pollination were to increase fruit set, and/or fruit quality (78% of crops). Hand pollination is practiced in large- and small-scale farming, home gardens, and greenhouses. Opportunities of hand pollination are the control of pollen origin and quantity, pollination timing and frequency as well as independence from environmental fluctuations. Farmers can increase yields, improve fruit quality, avoid fruit abortion, increase employment, and secure subsistence food. The main constraints of hand pollination are high labor inputs, high material costs, and required skills. Major risks of hand pollination include management ignoring pollinator conservation, high food prices, over-pollination, labor accidents, and unfair labor. We conclude that in the face of global change, hand pollination allows improved control of pollination and is likely to increase in importance. The benefits of hand pollination need to outweigh the costs and fair labor is essential. Altogether, hand pollination can be a valuable tool for crop systems where pollinators are absent or are not reliable for sustaining high-quality crop production.

Flowers of Meliaceae are traditionally described as bisexual, but functionally unisexual flowers have been reported for many genera. For Trichilia, several reproductive systems have been previously reported: subdioecy, gynodioecy, polygamy and hermaphroditism. The aim of this study was to analyze the occurrence of floral dimorphism and sexual-functional aspects of the flower of Trichilia claussenii. Structural and developmental analyses of flowers of Trichilia claussenii were performed using light and electron microscopy. In addition, male and female function of flowers was investigated through pollen viability and stigma receptivity tests, hand pollination and seed germination. Two floral morphotypes were identified in Trichilia claussenii: one morphologically male with a reduced gynoecium and the other morphologically female with anthers which do not release pollen. In the supposedly male flower, anthers are well developed and produce viable pollen grains. A conspicuous nectary disk differentiates at the base of the gynoecium, and the ovary has small ovules; however, our study proved that this ovary develops into a fruit, which contains viable seeds. In contrast, the supposedly female flower has larger gynoecium and ovules, and the nectary is smaller and inconspicuous. The stamens of female flowers have inviable pollen grains due to a tapetal necrotic product that keeps them united into an amorphous mass within the anthers. Male flowers are geitonogamous. Our results demonstrate that Trichilia claussenii exhibits subtle sexual floral dimorphism with female flowers and bisexual flowers distributed in different individuals. Our results indicate that male sterility occurs in only one morphotype; therefore, the species is gynodioecious.

Sterility and low seed set in bananas is the main challenge to their conventional genetic improvement. The first step to seed set in a banana breeding program depends on pollination at the right time to ensure effective fertilization. This study aimed at determining bract opening time (BOT) to enhance efficient pollination and seed set in bananas. A Nikon D810 digital camera was set-up to take pictures of growing banana inflorescences at five-minute intervals and time-lapse movies were developed at a speed of 30 frames per second to allow real-time monitoring of BOT. Genotypes studied included wild banana (1), Mchare (2), Matooke (4), Matooke hybrid (1), and plantain (1). Events of bract opening initiated by bract lift for female flowers (P P P P

Herbivory in plant reproductive tissues can severely reduce the fitness of the species, especially for those threatened with extinction. We investigated aspects of the reproductive ecology of Neoregelia ibitipocensis (Leme) Leme, an endangered species restricted to a few cloud forests sites in the Brazilian Atlantic Forest. Data on breeding systems, fertility, and viability of its populations are provided, as well as alternatives for development of strategies for ex situ conservation. Hand pollination experiments revealed that N. ibitipocensis is partially self-incompatible. Fruit and seeds were affected by intense herbivory caused by Tipulidae (Diptera) larvae. The predation reached 100% of the analysed infructescences during the first year of the study. We observed the production of parthenocarpic fruit both through controlled pollination experiments and under natural conditions. The potential for self-pollination and autogamy probably compensate for the reduced ability of the species to attract pollinators due to its small floral display. In the same way, parthenocarpy seems to represent a strategy to enhance the fitness of N. ibitipocensis, mitigating the effects of the predation. We developed an efficient protocol of in vitro multiplication, which represents a viable alternative for ex situ conservation of the species.

Passion fruit plants are self-incompatible and fruiting is exclusively dependent on cross-pollination, which in nature is performed by carpenter (mamangava) bees, especially Xylocopa spp. (family Apidae). To ensure satisfactory productivity, daily manual pollination is a common practice among passionflower growers. Therefore, we studied whether manual pollination mechanically transmits the cowpea aphid-borne mosaic virus (CABMV), the causal agent of the passion fruit woodiness disease. None of the eight healthy passion fruit plants manually pollinated with pollen from CABMV field-infected plants were infected, as confirmed by PTA-ELISA and RT-PCR. Healthy passion fruit plants mechanically inoculated with extracts of pollen collected from flowers of CABMV field-infected plants were not infected. CABMV was only detected by RT-PCR in groups of three anthers, and in pollen from groups of 20 anthers collected from flowers of infected passion fruit plants. RT-qPCR conducted with different amounts of pollen grains and anthers indicated extremely low virus titers. In addition to low virus titers, transmission failure may be associated with an absence of virus particles outside the pollen grains and/or absence of enough wounding produced on the stigmas by the fingertips. The improbability of CABMV transmission via pollen during manual pollination showed that this widely used cultural practice is a negligible factor in the epidemiology of passion fruit woodiness disease.

Interspecific hybrids between pearl millet (Pennisetum glaucum) and napier grass (Pennisetum purpureum) give rise to perennial fodder crops characterized by high biomass, broad clumps and good palatability. These hybrids are triploid and developed by hand pollination of napier grass pollen on pearl millet panicles. The progeny shows a high percentage of pearl millet genotype due to self-pollination in the female parent. Identification of hybrids at a young stage based on morphological characters is difficult. DNA-based molecular markers have high discriminating power and were used to assess genetic differences between hybrids and their parents. Genetic diversity was studied in 18 pearl millet × napier grass hybrids along with their parents and two released national checks using inter simple sequence repeat (ISSR) markers. Eight ISSR primers gave rise to 125 bands, of which 120 bands were polymorphic. Polymorphic information content and ISSR primer index ranged from 0.40 to 0.49 and 8.88 to 11.14, respectively. The hybrids showed the presence of unique bands, besides those shared with male and female parents. Female (pearl millet) parents formed a separate group in the dendrogram constructed based on ISSR polymorphism. The male (napier grass) parents formed a separate group along with hybrids, indicating a higher similarity of hybrids with the male parents. Principal component analysis and STRUCTURE analyses showed a similar grouping. The close resemblance of hybrids to the male parents confirmed their interspecific origin. The study revealed that ISSR marker analysis could be a quick and reliable method to identify interspecific hybrids at an early stage of growth.

The reproductive biology of the cassava genus (Manihot, Euphorbiaceae) remains unknown, despite its relevance to humanity. Here, we investigated the pollination system of two cassava wild relatives concerning the filtering of visitors in unisexual flowers, the specialization–generalization degree, and verified the dependency on pollinators for seed production. We studied two monoecious species M. violacea and M. oligantha on floral traits differences and visitors during flowering periods in natural conditions. For specialization–generalization degree analysis, we grouped pollinators into functional groups. We performed hand pollination treatments to verify the mating system. About half of floral visitors visited a floral type exclusively. The sexually dimorphic floral display contributed to filtering abundant pollinators, whereas nectar traits acted as attractant filter. In addition to polysaccharides, a remarkable presence of alkaloids and terpenes was observed in the nectary tissue of both male and female flowers. The species exhibited specialization associated with distinct functional groups, M. violacea with bees and M. oligantha with flies. The two Manihot species presented self-compatibility and depend on pollinators to produce seeds and the threatened species M. oligantha manifested pollen limitation. Our findings evidence conspicuous filtering of visitors and consequently, a specialized pollination system emerged for the two Manihot species despite the apparent generalist flowers. The reproductive success relying on groups of abundant pollinators suggests a threatening scenario to cassava wild relatives due to the worldwide decline of insect abundance.

Habenaria is one of the largest terrestrial genera in the family Orchidaceae. Most field studies on Habenaria species with greenish–white and nocturnal scented flowers are pollinated by nocturnal hawkmoths and settling moths. However, H. rhodocheila presents reddish flowers lacking a detectable scent and fails to fit the moth pollination syndrome. We investigated the pollinators, breeding system, and functional traits of H. rhodocheila in South China and found that two diurnal swallowtail butterflies Papilio helenus and Papilio nephelus (Papilionidae) were the effective pollinators. When butterflies foraged for nectar in the spur, the pollinia became attached between the palpi. A triangular projected median rostellar lobe was found at the entrance (sinus) of the spur of H. rhodocheila. This lobe divided the spur opening into two entrances forcing butterflies to enter their proboscides through the left or right side. When the projection of median rostellar lobe was removed, the site of pollinium attachment changed to the eyes of the butterflies, leading to a higher rate of pollinium removal but lower rate of pollinium deposition. Our quartz glass cylinder choice experiment suggested that visual rather than olfactory cues provided the major stimuli for butterflies to locate these flowers. Hand pollination experiments suggested this species was self‐compatible but pollinator‐dependent. However, the proportion of seeds with large embryos produced in self‐pollinated fruits was significantly lower than in cross‐pollinated fruits, indicating a significant inbreeding depression. Unlike many other orchid species, fruit set was higher than rates of pollinium removal, indicating a high level of pollination efficiency in a species with friable pollinia. Shifts from moth to butterfly pollination in the genus Habenaria parallel other orchid lineages providing insights into the potential for pollinator‐mediated floral trait selection., Two diurnal swallowtail butterflies Papilio helenus and Papilio nephelus (Papilionidae) were the effective pollinators of Habenaria rhodocheila. Visual rather than olfactory cues provided the major stimuli for butterflies to locate these flowers. The proportion of seeds with large embryos produced in self‐pollinated fruits was significantly lower than in cross‐pollinated fruits, indicating a significant inbreeding depression.

Animal-mediated pollination is an essential ecosystem service on which over a third of the world's agricultural crops depend. Blueberry fruit production is highly dependent on animal pollination and although visited by a range of bee species in their native range and agricultural settings, bumble bees are thought to be their primary native pollinators. Demand for blueberries has increased in recent years due to their perceived health benefits. Consequently, blueberry cultivation has expanded well beyond their native and original agricultural range, including several regions where bumble bees are not present. In South Africa, like many areas in the world, honey bees are the only commercially available pollinators for blueberries because many countries ban the importation of bumble bees. This study aimed to determine the benefits of honey bee pollination on blueberry fruit yield for the variety Ventura by comparing yields of honey bee-pollinated flowers to flowers where pollinators were excluded. Our results show that honey bees significantly increased berry mass and diameter. We conclude that Ventura in South Africa can be pollinated by honey bees, and that honey bee pollination can be an effective substitute for bumble bees in areas where bumble bees are unavailable. We also determined the extent to which blueberry yields could be improved by comparing fruit yield under honey bee pollination to fruit yield achieved through hand pollination. We found that honey bee pollinated blueberry yields were lower than yields achieved through hand pollination, suggesting that there is potentially room to improve honey bee pollination. Furthermore, we offer a conceptual figure to demonstrate how yield obtained through pollinator exclusion, open pollination, and hand pollination relate to each other. Additional research is required to study how beneficial honey bees are to fruit yield on other blueberry varieties as the benefits of honey bees are likely to vary depending on the variety.

The present study was carried out on eleven year old vines of Hayward (female cultivar) and Tomuri and Matua (male cultivars) at Zangam orchard of Department of Horticulture (J&K) trained on T bar trellis system. The fruit set and yield characteristics of Hayward were signifcantly infuenced by the pollen source. Among the various treatment combinations irrespective of the source of pollen, hand pollination at 90% bloom + spray of 0.1% borax (Na2B4O7.10H2O) and 0.4% ZnSO4 enhanced both fruit set and yield characteristics. Tomuri cultivar proved to be a good pollen source for desired fruit characteristic, and hand pollination supplemented with boron and zinc exhibited benefcial effects on all the afore-mentioned parameters of pistillate cv. Hayward.

The importance of wild insects as pollinators of tropical tree crops has rarely been tested. Across 18 small-scale lychee orchards in northern Thailand, we evaluated the roles of different wild insects as pollinators and predators of pests in fruit production. Quantitative assessments showed that bees (Family Apidae) were strongly dominant (83%) among insect flower visitors, comprising four species in tribes Apini and four in Meliponini. Experimental manipulations of inflorescences showed that fruit production in these orchards was: (1) dependent on flower visits by wild insects because enclosure of inflorescences in mesh bags decreased fruit set (to one-fifth) and (2) not greatly limited by pollinator deficiencies, because hand pollination of unbagged flowers did not enhance fruit set. Pollination success, as indicated by the proportion of unmanipulated flowers setting fruit, correlated positively across orchards with the abundance of large-bodied Apidae (>7 mm; most were Apis species) and of Apini, and negatively with abundance of small-bodied Apidae and of all Meliponini, despite the latter being the commonest flower visitors. We conclude that larger-bodied bees are most likely to travel sufficiently far to import genetically diverse pollen, in this landscape-scale mosaic where non-orchard habitats (both agriculture and treed patches) were sufficient to sustain wild pollinators.

We investigated the fruit set and quality of yellow passion fruit subjected to hand and natural pollination by carpenter bees (Xylocopa spp.) in the Philippines. We also recorded the foraging behav...

Theory predicts that herbivory should primarily determine the evolution of herbivore-induced plasticity in plant defenses, but little is known about the influence of other interactions such as pollination. Pollinators may exert negative selection on the herbivore-induced plasticity of chemical defenses when floral signals and rewards are indirectly affected, provoking deterrent effects on these mutualists. We investigated the influence of constant herbivory and pollination on the evolved patterns and degree of herbivore-induced plasticity in chemical plant defenses and floral morphometry and volatiles in fast-cycling Brassica rapa plants. To do this, we used plants from an evolution experiment that had evolved under bee/hand pollination and herbivory manipulated in a 2 × 2 factorial design during six generations, producing four selection treatments. We grew sibling plant pairs from each of the four selection treatments of the last generation and infested one group with herbivores and left the other uninfested. Herbivore-induced plasticity was analyzed within- and between-selection treatments. We found support for the hypothesis that constant herbivory favors the evolution of higher constitutive yet lower herbivore-induced plasticity in defenses. However, this only occurred in plants that evolved under hand pollination and constant herbivory. Bee pollination had a strong influence on the evolution of herbivore-induced plasticity of all traits studied. Plants that evolved under bee pollination, with and without constant herbivory, showed remarkably similar patterns of herbivore-induced plasticity in their defense- and floral traits and had a higher number of plastic responses compared to plants with hand pollination. Such patterns support the hypothesis that bee pollination influenced the evolution of herbivore-induced plasticity, most likely via indirect effects, such as links between defense- and floral traits. We conclude that interactions other than herbivory, such as pollination, may impact herbivore-induced plasticity, through indirect effects and metabolic trade-offs, when it contributes to trait evolution in plants.

The production of fruits and seeds of many crops is increased when external pollination occurs. Although self pollination is a widespread biological process in cultivated grapevines, there are still some uncertainties about the consequences of cross fertilization regarding productivity and quality of grapevines. Fertilization biology of grapevines becomes an essential issue when protected cultivation in particular is considered. The present investigations were therefore performed to clarify the possible effects of different pollination treatments on the agronomic features of 'Perle de Csaba' and 'Trakya Ilkeren' table grape cultivars. Before the anthesis, clusters of self-pollination treatment were enclosed within cheesecloth frames to avoid extraneous pollination. For the free pollination group, flowers of twelve similar clusters were allowed to bloom and pollinate spontaneously, while hand pollination was performed by transporting the mixture of external pollens gathered from different cultivars at bloom stage. In 'Perle de Csaba' cultivar, hand pollination and free pollination treatments significantly increased the overall agronomic parameters on berry set rate, berry development, cluster size, seed weight and seed size in comparison to self pollination. Treatments had similar effects in 'Trakya Ilkeren', except for a few parameters such as cluster length, berry diameter and seed thickness. Overall results indicated that cross pollination would considerably increase the quantity and quality of table grapes when cultivated under protected conditions such as glass or greenhouses.

Insect pollination plays a vital role for the yield of many crops, such as apples, strawberries and coffee, which are economically significant commodities on the global market. Yet, knowledge about the role of insect pollination is lacking for many cash crops that support the livelihoods of small-scale farmers in developing countries. To assess if yields of watermelon are pollen limited, we conducted a supplemental hand-pollinated experiment (using a pollen mixture of cross and self-pollen) in 13 small-scale farms in an agricultural landscape in the Kilimanjaro and Arusha regions in northern Tanzania. We assessed fruit set, fruit abortion and weight of the mature fruits stemming from hand pollinated and control flowers. To check if differences in yield responses between hand-pollinated and control treatments depended on resource availability, we also accounted for local soil conditions. We found that hand pollination (i) increased the probability of fruit initiation by 30%, (ii) reduced the probability of fruit abortion by 13%, (iii) increased the probability of flowers developing into mature fruits by 42% and (iv) increased average fruit weight by 1.3 kg (±0.15 SE). Our results indicate that our system is pollen limited, due to insufficient visitor frequency and/or inefficient pollinator species. Fruit initiation and fruit weight were positively related to soil carbon, irrespective of treatment. The influence of soil moisture was not consistent across the measured responses, and differed between hand-pollinated and the control treatments. We suggest that farmers in our focal area should focus on improving the quality of the landscape to sustain and enhance healthy pollinator communities ultimately improving yields. We also suggest that farmers should continue current practices with respect to fertilization. The role of soil moisture on fruit initiation and maturation should be investigated to ensure that the positive effects of pollen is not hindered by soil moisture conditions.

Sinocalycanthus chinensis Cheng et S. Y. Chang (Calycanthaceae), which has a unique systematic status, is listed as a national second‐class protected plant of China. In this study, the genetic diversity, performance, and fitness of F1 progeny from crosses between the Damingshan (DMS) population of S. chinensis and pollen parents from the Daleishan (DLS) and Longxushan (LXS) populations were examined. The DLS population has a relatively small population size, low genetic diversity, and considerable geographical and genetic distances from the DMS population relative to the LXS population. Compared with naturally occurring seeds, DLS‐sired seeds had the highest thousand‐seed weight, starch content, fat content, germination rate, germination index, and emergence rate, but the lowest protein content. Naturally occurring, open‐pollinated seeds had the lowest thousand‐seed weight, starch content, and fat content, but the highest protein content. Compared with natural F1 progeny, DMS × DLS seedlings had the highest genetic diversity, photosynthetic parameters, and growth characteristics, except for leaf mass ratio and stem mass ratio. Under strong light, DMS × DLS seedlings exhibited a Fv/Fm value of 0.75, while the other two seedling types exhibited Fv/Fm values of 0.65. DLS‐sired seeds had the most vigorous growth characteristics except for leaf mass ratio and stem mass ratio. These results suggest that genetic rescue by transplanting seedlings from the DLS population or hand pollination with pollen from the DLS population would be effective methods to reduce inbreeding depression and obtain strong offspring with high genetic diversity and fitness in the DMS population.

The family Cactaceae possesses considerable floral diversity and is exclusively zoophilic. Cipocereus crassisepalus is an endangered species of columnar cactus, whose floral characteristics fit the chiropterophily syndrome. This study aimed to assess the correspondence between floral traits and pollinators and whether the pollination system of C. crassisepalus is specialized, as suggested by the hypothesis of geographical dichotomy. Hand pollination treatments demonstrated that C. crassisepalus depends on cross-pollen flow mediated by pollinators to set fruit and seeds. Nocturnal film recordings, diurnal observations, analyses of pollen loads of flower visitors and visitor exclusion experiments provided strong evidence that bats are the sole pollinators of this cactus. During two flowering seasons, pollen grains of C. crassisepalus were found only on the bodies of the bat Anoura caudifer. Cipocereus crassisepalus possesses a pollination system specialized on nectar-feeding bats, which corroborates the geographical dichotomy hypothesis.

Nature in Singapore, Supplement 1, 219-230

A study was conducted in a yard long bean (Vigna unguiculata sup/ssp. sesquipedalis) hybrid VS 50 (Kakkamoola Local) x VS 26 (Vellayani Jyothika) to assess the percentage fruit set at two time intervals and to identify the best time interval for pollination in yard long bean hybrids. Hand pollination was done using VS 50 as female parent and VS 26 as male parent for seven consecutive days at two time intervals, 6.30 – 7.30 am and 7.30 – 8.30 am. Higher percentage of fruit set (36.8 %) was observed between 6:30 – 7:30 a.m. as compared to the time interval 7:30 – 8:30 am. (23.8%). Pollen viability was determined for the parents VS 50 (Kakkamoola Local) and VS 26 (Vellayani Jyothika) at 6.30, 7.30 and 8.30 am. Highest pollen viability for both the parents VS 50 and VS 26 was observed during 7.30 am. The present study shows that the best time interval for crossing in yard long bean is 6.30- 7.30 a.m.

Aims: This field experiment was conducted to determine if hand and open pollination methods affected performances of Musa progenies from 4x - 2x crosses and to identify promising progenies for recurrent selection. Study Design: The experimental design was a randomized complete block design with two replications of 6 plants per genotype. Place and Duration of Study: International Institute of Tropical Agriculture (IITA) High Rainfall Station, Onne (4º51’N, 7º03’E, 10 m above sea level), in Rivers State, South-south Nigeria for 24 months. Methodology: Two-month old seedlings of hand pollinated (6 diploid, 6 tetraploid) and open pollinated (6 diploid, 6 tetraploid) progenies, along with parental clones (2x) and (4x) of each genotype were planted at 3 m x 2 m spacing. Data on phenology, vegetative growth, yield and yield characters were collected at flowering and harvest over three crop cycles. Genotypes were partitioned into 5 clusters assayed by means of orthogonal contrasts to compare the performance of progenies from both pollination methods. Results: Pollination methods produced no significant (P = .05) differences, unfavourable effects or reduction in performance of economically important yield and yield components of 4x and 2x progenies of similar genotype. Some significant (P = .05) linear correlations and relationships between phenological and vegetative traits; and yield and yield components changed with pollination methods and ploidy levels but did not affect final outcomes. Promising open pollinated diploids include the early maturing TMP2x 2829-62OP; and for high yield and yield components measured, TMB2x 8084-2OP and TMP2x 1448-1OP. Promising open pollinated tetraploids include TMP4x 7002-1OP and TMP4x 2796-5OP. Conclusion: Open pollination did not result in unfavorable effects or reduction in performance of economically important yield and yield components in progenies of similar genotypes. Therefore, open pollination could be considered for Musa breeding. This will reduce cost, labour, time and stress involved in Musa improvement.

In the intense solar radiation of an alpine climate, small black bees often experience extremely high thoracic temperatures when they are foraging on flowers, but flies forage at lower temperatures. To explore the hypothesis that seed set could be depressed by transient dehydration of pollen at the high temperatures reached by hot bees foraging in sunshine, we compared the effectiveness of single visits by different pollinators to a bowl-shaped flower Potentilla lancinata in alpine meadows, SW China. The ratio of seed set to pollen transferred in individual flowers was monitored over 2 years, indicating that pollen deposited on stigmas by halictid bees produced lower seed set than pollen carried by flies. Scopal pollen applied to stigmas by hand gave good seed set, but in germination tests it burst more frequently than pollen from anthers, implying dehydration. Pollen grains freshly taken from the scopae of solitary bees foraging in sunshine were smaller than those taken from anthers or foraging bees in early-morning overcast conditions, implying dehydration. The effect was reversible: hand pollination showed that scopal pollen was no less effective than fly pollen after removal from the bee. Pollen carried by such bees foraging in intense sunlight in flowers became dehydrated, causing an osmotic mismatch between the pollen and the stigmas. Transient heat-induced dehydration of pollen represents a novel pathway by which climate warming may disrupt plant reproduction, and helps us understand why flies could be more effective pollinators than bees in cool, high-radiation arctic or high-altitude sites.

Premise Most plants interact with mycorrhizal fungi and animal pollinators simultaneously. Yet, whether mycorrhizae affect traits important to pollination remains poorly understood and may depend on the match between host and fungal genotypes. Here, we examined how ericoid mycorrhizal fungi affected flowering phenology, floral traits, and reproductive success, among eight genotypes of highbush blueberry, Vaccinium corymbosum (Ericaceae). We asked three overarching questions: (1) Do genotypes differ in response to inoculation? (2) How does inoculation affect floral and flowering traits? (3) Are inoculated plants more attractive to pollinators and less pollen limited than non-inoculated plants of the same genotype? Methods To examine these questions, we experimentally inoculated plants with ericoid mycorrhizal fungi, grew the plants in the field, and measured flowering and floral traits over 2 years. In year 2, we conducted a hand-pollination experiment to test whether plants differed in pollen limitation. Results Inoculated plants had significantly higher levels of colonization for some genotypes, and there were significant floral trait changes in inoculated plants for some genotypes as well. On average, inoculated plants produced significantly larger floral displays, more fruits per inflorescence, and heavier fruits with lower sugar content, than non-inoculated, control plants. Hand pollination enhanced the production of fruits, and fruit mass, for non-inoculated plants but not for those that were inoculated. Conclusions Our results demonstrate that inoculation with ericoid mycorrhizal fungi enhanced flowering and altered investment in reproduction in genotype-specific ways. These findings underscore the importance of examining belowground symbionts and genotype-specific responses in their hosts to fully understand the drivers of aboveground interactions.

Distyly is a genetic polymorphism composed of long-and short-styled flowers in a population. The evolutionary breakdown of distyly has been reported in many taxa, and mainly involves a shift toward monomorphism or dioecism. However, a shift toward monoecism has not been reported in distylous species. Psychotria (Rubiaceae), one of the world largest genera, consists of distylous species and their derivatives. In our preliminary study, however, we identified some monoecious individuals in a population of Psychotria manillensis. To understand the breeding system and reproductive biology of P. manillensis, we investigated floral traits, open fruit set, and flower visitors, and performed hand pollination and bagging experiments in five populations of Okinawa and Iriomote islands, Ryukyu Islands, Japan. The populations of P. manillensis were composed mainly of monoecious individuals (54%), followed by female (30%), male (14%), and hermaphroditic (2%) individuals at the time of flower collection. Of the collected flowers, 93% were functionally unisexual (male or female), whereas only 6.5% were perfect (hermaphroditic). However, some individuals changed sex mainly towards increasing femaleness during the flowering period. Moreover, 35% of the studied plants changed their sexual expression over the years. P. manillensis showed self-compatibility and no agamospermy. The fruit set under open pollination varied among populations and years (1.8–21.9%), but it was significantly higher than that of auto-selfing (0.68–1.56%). Wasps and flies were the main flower visitors and probably the main pollinators of the species. In conclusion, P. manillensis was revealed to be polygamous, involving monoecious, female, male, and hermaphroditic individuals. This is the first report of the polygamous breeding system not only in the genus Psychotria, but also in all heterostylous taxa.

Inadequate quantity and quality of pollen reaching the stigmas decreases the sexual reproductive output of plants, compromising yield. Still, the current extent of pollen limitation affecting yield (i.e., pollination deficits) is poorly quantified. This study is aimed at quantifying pollination deficits in kiwifruit orchards, a dioecious plant with a fruit caliber and market value largely dependent on pollination services. For that, we set up a pollination experiment and quantified services and yield provided by current pollination vectors, and under optimal pollination, over two years in a total of twenty-three orchards covering the kiwifruit production range in Portugal. We characterized nine fruit traits and used: (1) fruit weight to calculate pollination deficits and relate them with pollinator diversity and abundance, and environmental variables, and (2) production values, fruit caliber, and market values to calculate economic impact of pollination deficits. Results showed that pollination deficits were variable in time and space and were significantly and negatively correlated with pollinator abundance, while the opposite pattern was obtained for production, supporting the notion that a higher pollinator’s abundance is related to lower pollination deficits and higher yields. Understanding the factors affecting pollination deficits is crucial to depict the need for nature-based solutions promoting pollinators and to resort to management practices assisting pollination.

Pollination is the process by which pollen grains are exchanged in plant flowers to allow for fertilisation and production to take place. However, challenges occur when crops are grown under protected structures where there are minimal activities of natural pollination agents such as wind and animals which are responsible for transferring pollen grains from the anther to the stigma. Therefore, the study objective was to determine the effect on hand pollination on the yield of African horned cucumber grown under greenhouse and shade net environment. A factorial experiment with two factors (hand pollinated and non-hand pollinated/control) was conducted under two different growing environments (greenhouse and shade net). African horned cucumber plants were hand self-pollinated in the morning. Pollen were manually transferred with a hand using the new earbud from the male to the female flowers on the same plant (selfing). Results showed that hand pollinated African horned cucumber plants increased total biomass from 0.93 to 2.23 kg under greenhouse environment. Hand pollinated plants increased harvest index from 0.07 to 0.35 under shade net environment. It can thus, be deduced that hand pollination increases African horned cucumber yield in the greenhouse and shade net environments.

In red clover seed production, low seed yield is limiting the commercial exploitation of tetraploid red clover. To explore if pollination is the limiting factor for the seed yield in tetraploid red clover, we investigated pollinator behaviour and plant reproductive success in diploid (2x) cultivar ‘Rajah' and tetraploid (4x) cultivar ‘Amos' using honey bee and hand pollination approaches. We measured the seed set at the flower head level with the increasing visitation rate of honey bees (one bee, two bees and open pollination) and pollen diversity (one and two pollen donors) of hand pollination. We found no difference in honey bee pollination behaviour (visitation rate) between the diploid and tetraploid red clover. Surprisingly, the seed set in two bees was significantly lower than that of one bee in ‘Rajah'. We suggest that honey bees prefer to visit already tripped florets or to visit fewer florets due to scent marks left by the previous honey bees. In open pollination, seed number per flower head in ‘Amos' (on average 11) was half of ‘Rajah' (on average 20). Seed set in ‘Amos' was lower than 50% of ‘Rajah' in honey bee (one bee treatment) and hand pollination (one and two pollen donors treatments). There were no differences in stigma receptivity whereas pollen viability in ‘Amos' was lower than ‘Rajah' after the peak pollen viability was reached (six days after the onset of flowering). We suggest that the fertility problems such as low pollen viability may be the reason for the low seed set in tetraploid red clover. This conclusion should be verified by investigating other fertility traits during the ovary, embryo and seed development with a broader range of diploid and tetraploid cultivars.

The societal and economic benefits of ecosystem services are both immense and multi-faceted. To holistically quantify the contribution of pollinators to agriculture requires measuring multiple indices of crop production beyond crop yield. Here, we conduct a field-based hand pollination experiment to measure the effects of self and outcross pollen on fiber yield and quality in conventionally managed cotton crops. First, we determine how different pollination treatments affect specific indices of fiber yield and fiber quality, including fiber length and fineness. Second, we investigate the suggested tradeoff between fiber yield and quality. We find that flowers receiving outcross pollen produce larger, heavier bolls than either self-crossed or non-crossed flowers. However, contrary to expectation, flowers of different treatments are indistinguishable in terms of fiber quality. Overall, we find that pollination treatment has no discernable effect on either fiber length or fiber fineness. Understanding the contribution of ecosystem services across multiple axes provides growers with information concerning potential tradeoffs or synergies, and offers insight into management decisions.

During the breeding program studies, the pollen donor parents (pollinizers) were observed to be characterized by a strong flowering rate and very low fruit set, even after hand pollination. Then the notion of pollinizers in the argane species was born, first mentioned, checked, documented and confirmed like other conventional tree species. Since the argane tree is completely self-incompatible, the presence of compatible pollinizers is necessary for the fruit set. Indeed, pollinizers need to be selected accurately based on the synchronization of bloom periods and compatibility to receiver trees (female). The pollinizer is essential in any breeding program and for new orchard plantations. The current study was conducted on 13 argane genotypes including two pollinizers. The flowering period, bloom phenology, floral structure and fruit set of crossed genotypes were monitored, illustrated and a season phenogram was established. The pollen viability and germination were also evaluated. In order to test compatibility, the hand pollination using two selected pollinizer pollens was compared to open pollination. Then, the compatibility system was monitored and evaluated through analysis of crossing diallel programs and through the index of self-incompatibility. The flowering periods are genotype depending and one to three blooms have been observed during the two years study (2018-2019) and the argane tree is a tristylous species (Mesostylous, brevistylous and longistylous flowers). Thein vitrotests showed that the pollen originated from crossed genotypes were viable and able to germinate. The cross-compatibility rate depends on cross associations and it varies from 39 to 84 %. In fact, this study showed that the effect of pollen-parent (xenia) occurs in all fruit components of argane tree. It was observed, for the first time, that both compatible pollinizers and xenic effects of pollen on argane fruit have occurred. Artificial pollination is currently feasible for breeding programs and the screening of elite genotypes. Then the selected pollinizer is quite required for the development of argane tree cropping.HighlightsPollinizers in the argane species first mentionedPollinizer is essential in any breeding program and for new orchard plantationsArgane tree is self-incompatiblePollen-parent effect, (xenia) occurs in all fruit components of argane tree

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.

When plants are removed from their native habitat, reproduction can be compromised if pollinators are absent, especially when plant-pollinator interactions are species-specific and the plant is self-incompatible. To avoid these pitfalls, botanic gardens often use hand pollination to ensure reproductive success of their living collections, an important aspect of ex-situ conservation. The nipa palm, Nypa fruticans, presents an interesting case study of pollination in a botanic garden and a plant’s ability to successfully reproduce outside its native range without assisted pollination. Nypa fruticans has been growing at Montgomery Botanical Center (MBC) in South Florida since 1984, but for years required hand pollination to produce viable fruit. A recent shift from hand pollination to unassisted pollination suggests that this palm has found an alternative to fertilize its flowers. We investigate possible pollinators and new opportunities for pollination outside the palm’s native range. Rather than the insects typically associated with N. fruticans pollination in its native range in Southeast Asia (i.e., flies and beetles), ants, specifically Paratrechina longicornis, were overwhelmingly the most abundant visitors to nipa palm inflorescences at MBC and likely represent an important pollinator or facilitator of pollination at the garden. Pollination research at botanic gardens complements in-situ field studies and provides important insights into the flexibility of pollination systems to achieve reproductive success outside a plant’s native range.

Pollen limitation commonly exists in the alpine species, yet, experimental estimates on the changeable trajectory of pollen limitation along elevational changes are rarely. We used field observations and supplemental hand pollination treatment to estimate the variation in pollen limitation among five different altitudes populations (from 3600 m.a.s.l. to 4400 m.a.s.l.) in Meconopsis integrifolia in two consecutive years. Correlation analysis was used to estimate which factor incurred the pollen limitation. Hand supplemental pollination indicated that pollen limitation occurred in the studied populations in both years. Pollen limitation was similar among low-elevation populations but doubled in the highest elevation population (4452 m.a.s.l.). The number of pollinators and visitation rate of pollinators were negatively related to the pollen limitation. Our results indicated that number of pollinators and visitation rate of pollinators were the main factors which incurred variation in pollen limitation of M. integrifolia among different altitudes.

Male–male competition for mating or fertilization opportunities may in theory select for male manipulative adaptation that can harm males’ mates, leading to sexual conflict. Evolutionary theory predicts that selection will favor the manipulation by pollen of the duration of its recipients’ receptivity. However, there is insufficient evidence to show that pollen can exert effects on the duration of receptivity, a prerequisite for the evolution of pollen manipulative adaptation. Using a sexual diploid dandelion, Taraxacum japonicum, we conducted hand pollination experiments within and between populations to examine the effects of pollen on the timing of inflorescence (flower head) closure. We also examined the potential fitness consequences to the pollen recipients by field observation of seed production in populations with different inflorescence closure timing. Within-population experiments showed that pollination induced inflorescence closure even when some of the florets in the inflorescence were not yet pollinated with compatible pollen. Furthermore, between-population crosses revealed that pollen donors, recipients, and their interaction all influenced the timing of inflorescence closure. Different populations differed in the timing of inflorescence closure, which could affect the availability to the recipients of pollen for fertilization and thereby seed production. However, there were no significant differences in the rates of natural seed production in these populations. Our results demonstrate that pollen donors, as well as recipients, contribute to the duration of floral receptivity. We discuss the implications of our findings to the evolutionary theory of plant reproduction.

The main aim of the peach breeding program in the Steppe branch of Nikitsky Botanical Gardens developed in 1975 was to obtain new adapted cultivars, which combine most valuable biological and economic traits. Standard breeding techniques such as crossing, hand pollination, self-pollination and open pollination, were employed. Best foreign and domestic cultivars were used as parents. Mother cultivars were ‘Valiant’, ‘Veteran’, ‘Laureate’, ‘Red Haven’, ‘Santarine’, ‘Start’, and ‘9251’, fathers cultivars were: ‘Cardinal’, ‘Kudesnik’, ‘Miryanin’, ‘Sanrise’, ‘Favourite Morettiny’ and ‘Kievskiy Ranniy’. A large hybrid fund was created and studied. As a result distinguished peach hybrids were identified and selected. This paper focuses on some biological and economic features of 42 selected elite forms of 12 peach hybrid combinations of F1 and F2. They are characterized by high productivity, good quality of fruits and excellent taste. Some of these elite forms are superior to existing national standards by crop yield, winter hardiness, appearance and fruit quality. So they were registered as cultivars, such as: ‘Vavilovskiy’, ‘Demerdzhinskiy’, ‘Kandidatskiy’, ‘Posol Mira’, ‘Osvezhayuschiy’ and ‘Jubilejnyiy Ranniy’. Some biological and economic characteristics (fruit size, skin, colour and over colour, flesh firmness, taste of the fruit, yield, etc.) of these cultivars are presented.

Experiment was conducted in the rainforest agro-eco-zone of Southeastern Nigeria under rain fed condition at the sweet potato breeding ground of National Root Crops Research Institute, Umudike, Nigeria to generate 10,000 botanical seeds for further evaluation for high root yield, dry matter and micro-nutrient content, to identify high flowering parent(s) and to select compatible parent(s) for further genetic recombination. The treatment which consisted of 14 parents of bi-parental crossing was laid out in a randomized complete block design with seven parents, each per plot per block and replicated three times while the other seven parents were maintained in different plots as pollen donors. Data collected were on: total number of emerged flowers visually counted, total number of flowers covered, total number of flowers pollinated, total number of capsules formed, total number of flowers aborted, total number of seeds obtained from crosses, number of good seeds, number of unfilled seeds, percentage of good seeds. Data collected were statistically analyzed using Statistical Package for Social Sciences (SPSS, version 15.0). Differences between means were tested using analysis of variance (ANOVA) while means separation was done using standard error of difference means at 5% probability. The results obtained showed that despite the seemingly high total number of flowers produced from the controlled crosses (14520), only 17.4% of this figure yielded good seeds. The objective of realizing 10,000 botanical seeds through the hand pollination was not achieved as a result of high flower abortion arising probably from moisture stress which was severe during seed filling. The variety Tio-joe gave the highest flower production of 2334. The relatively high number of capsules of 347obtained from the cross between UMUSPO 3 and NRSP/2 indicated high compatibility between the two parents which suggested that the two parents could be used for further recombination for micro-nutrient enhancement.

Background and Aims In plants, the spatial and genetic distance between mates can influence reproductive success and offspring fitness. Negative fitness consequences associated with the extremes of inbreeding and outbreeding suggest that there will be an intermediate optimal outcrossing distance (OOD), the scale and drivers of which remain poorly understood. In the bird-pollinated Anigozanthos manglesii (Haemodoraceae) we tested (1) for the presence of within-population OOD, (2) over what scale it occurs, and (3) for OOD under biologically realistic scenarios of multi-donor deposition associated with pollination by nectar-feeding birds. Methods We measured the impact of mate distance (spatial and genetic) on seed set, fruit size, seed mass, seed viability and germination success following hand pollination from (1) single donors across 0 m (self), Key results Inter-mate distance had a significant impact on single-donor reproductive success, with selfed and nearest-neighbour ( Conclusions Collectively, single- and multi-donor pollinations indicated evidence for a near-neighbour OOD within A. manglesii. A survey of the literature suggests that within-population OOD may be more characteristic of plants pollinated by birds than those pollinated by insects.

Bee-pollinated crops in landscapes with a low abundance of bees suffer from insufficient pollination. The present study investigates the effect of wild bee pollination on fruit and seed production in okra, Abelmoschus esculentus (L.) Moench. The study was conducted in a home garden, where an okra field was established for three pollination trials each to include 40 okra plants. For each trial, three sets of 25 flower buds were selected and tagged. One set was covered to deter bees, another set was kept open to enable bee visits and the other set was cross-pollinated by hand. Of the two species of bees, Tetragonula iridipennis (Smith) visited flowers for nectar while Lithurgus atratus Smith collected and carried pollen grains. The period of stigma receptivity and pollen availability coincided with the highest activity of L. atratus from 10.00 a.m. to 12.20 p.m. Bee-pollinated flowers had significantly enhanced okra pod length and diameter, seed number and seed germinability compared to the trial with flowers covered to deter bees. Hand pollinated flowers also produced significantly longer pods and a higher number of seeds with higher germinability. Although there was no significant difference in pod length and diameter and seed number between hand pollination trial and bee-pollinated trial, germinability of bee-pollinated seeds was significantly higher. Present study highlights the importance of the wild bee, L. atratus to enhance pod size, seed number and seed germinability in okra in Kurunegala, Sri Lanka.

Background and Aims Reproductive interference may reduce fitness of either of the involved species, with potentially important ecological and evolutionary consequences. Except for the effect of shared pollinators on reproductive success, however, mechanisms underlying reproductive interference have been little studied, even though the severity of its impact may depend on the specific mechanism. The aim of this study was therefore to explore the mechanisms of reproductive interference between Taraxacum japonicum (native to Japan) and Taraxacum officinale (alien). Methods In a field survey, the association between alien species density and seed set in T. japonicum, and whether pollinator behaviour indicated a preference for the alien, were examined. Effects of heterospecific pollen deposition were measured in a series of hand pollination experiments, including mixed pollination experiments in which the order of application of conspecific and heterospecific pollen was varied. Finally, to investigate hybridization frequency, the parentage of seedlings produced following natural, mixed or heterospecific pollination was compared. Key Results Alien species density did not negatively affect native seed set, nor did pollinators appear to have a preference for alien flowers. The hand pollination experiments showed that heterospecific pollen deposition adversely affected native seed set, especially when alien pollen was applied before conspecific pollen. No viable hybrids were found following natural pollination, which suggests that hybridization might be a rare event. Conclusion Among the examined mechanisms, heterospecific pollen deposition might have the largest deleterious effect on the native species. This effect is frequency dependent; thus, a positive feedback loop may cause the effect on the population dynamics to increase over time, with the result that the alien might eventually displace the native in a population. Effects of the examined mechanisms on population dynamics should be investigated further to improve understanding of the impact of reproductive interference on the structure of plant communities.

Breeding systems have been associated with polyploidization and genomic change, which have a central role in the diversification of Angiosperms. Polyploidy commonly leads to isolated populations and species, and sometimes to apomixis, as observed for some woody plants of Cerrado, the Neotropical savannas in Central Brazil. Eriotheca gracilipes and E. pubescens are common trees in this region, and present both sexual and sporophytic apomictic individuals. We studied here how morphological features and breeding systems are linked to ploidy and genome size differences, and how these features may help to understand cytotypes distribution. We confirmed breeding systems by hand pollination experiments and complemented histological analyses to describe the apomixis and sexual process for individuals with previously defined ploidy levels. We used flow cytometry and morphometry data to verify the relationships among cytotypes. Fruit and seed features were also measured for extensive samples of both species to observe environmental correlates such as altitude of occurrence and distribution of each embryony pattern and cytotypes. In both species, agamic complexes included individuals with nucellar polyembryony associated to putatively neopolyploid, hexaploid cytotypes, while lower ploidy individuals were sexual and self-sterile. Higher genome sizes were also associated with larger pollen grains and stomata, besides other more complex morphological trends. Embryonic patterns were consistent for each site, individuals, and along years, although the percentage of polyembryonic seeds and number of embryos per seed varied. Monoembryonic sexual individuals were associated with higher elevation, allegedly last glacial maximum Cerrado refuges, while polyembryonic sporophytic apomicts appeared in lower areas.

In most parts of the world pepper has become a popular spice that makes food hot in addition to its much needed nutrients of carotenoids and vitamins. This report has its objective to evaluate the parents and hybrid of three Nigerian pepper genotypes (Shombo, Tatase and Nsukka yellow pepper) for growth and yield; and to estimate their genetic parameters. Conventional breeding by hand pollination was adopted. The mean performance of the parents and hybrids for morpho-agronomic characters were evaluated. Heterosis and inbreeding depression were estimated. The F1 hybrids showed superiority over the parental genotypes with Sho x Nsky-rw having significantly (P ≤ 0.05) the highest value in most of the traits. In morphological traits, Sho x Nsky-rw hybrid had highest values in canopy diameter, number of leaves, number of nodes and number of branches per plant, while in fruit traits, it also had significantly the highest values in the number of fruits, fruit length and weight of fruits per plant. Sho x Nsky – rw had positive heterobeltiosis over the better parent in most of the yield and yield component characters. While Sho x Nsky – rw had the highest yield, Tat x Sho had the highest fruit wall thickness. The combinations of these traits are important to both the farmers and consumers. Having appropriate parents with genetic variability F1 pepper plants having distinct superiority above the mid and better parents could be developed. Key words: Capsicum annuum, chili pepper; heterosis, hybrid, inbreeding depression.