Low Fruit Set Research Articles

Pistil Biology of ‘WA 38’ Apple and Effect of Pollen Source on Pollen Tube Growth and Fruit Set

‘WA 38’ (‘Enterprise’ × ‘Honeycrisp’) is an apple variety that is characterized by a peculiar self-thinning trait in which most of the fruitlets naturally shed within the first 8 weeks after bloom, leaving some clusters empty, but most with 1–2 apples. This study aimed to investigate potential causes for the relatively low fruit set observed in ‘WA 38’ by investigating its flower biology. This study comprised three objectives: (1) To characterize the effective pollination period (EPP) of ‘WA 38’ by studying stigmatic receptivity, pollen tube growth, and ovule longevity in ‘WA 38’ flowers, (2) to compare the pollen tube growth of 5 fully compatible pollinizer varieties in ‘WA 38’ pistils, and (3) to evaluate fruit and seed set resulting from controlled pollinations with 5 fully compatible pollinizer varieties. The results showed ‘WA 38’ EPP was approximately 3.2 days in 2019 and 1.4 days in 2020, and that differences in pollen sources did not attribute significant differences in fertility in ‘WA 38’ flowers. The results of this study suggest mechanisms other than pollination and fertilization, such as competition among fruitlets within a cluster or hormone signaling, may have a stronger impact on ‘WA 38’ fruitlet abscission.

Rarity up in the mountain: Ecological niche modeling, phenology, and reproductive biology of the most commercialized Masdevallia species

Knowledge of how natural and anthropogenic factors can limit the distribution of rare species is key to develop conservation strategies. We show data on how both factors potentially affect the distribution of a rare high Andean orchid. We chose Masdevallia coccinea as a model because it is endangered and the most commercialized species of the entire genus. Using ecological niche modeling, we confirm its rarity, with a restricted potential occurrence equivalent to only 0.00005 % of South America, 0.0003 % of the Andes, and 0.0009 % of Colombia. We projected the future potential occurrence of M. coccinea and found that it can have a reduction of 43.49 % in the best-case scenario and 89.06 % in the worst-case scenario in 2100. We describe the flowering and fruiting phenologies and demonstrate that the precipitation two months before may determine the first one. Masdevallia coccinea is a rewardless species and, unlike most Pleurothallidinae species, we show that it is self-compatible but non-autonomous selfer. Thus, it is dependent on biotic pollination, performed only by Leucophenga sp. (Drosophilidae: Diptera) which has low efficiency (8.6 % of fruit set). This is the first pollinator report for the genus. While self-compatibility may be related to reproductive assurance, apparently inbreeding depression may affect populations since selfed fruits had less viable seeds. Nevertheless, self-pollination can be avoided by the retention of the anther cap on pollinia, giving more time until the pollinator flies away to another flower. We consider that the rarity of M. coccinea may be a result of both anthropogenic (habitat loss, climate change, and overcollection) and natural factors (high elevation distribution, self-compatibility, rewardless strategy, pollinator specificity, and low fruit set). The several new facets investigated here can be used for future conservation strategies of this emblematic species as well as other high Andean threatened species.

Pollination biology and reproductive success in four Brazilian species of Gomesa (Orchidaceae: Oncidiinae): Specific pollinators, but high pollen loss and low fruit set

AbstractFour species of Gomesa (Gomesa flexuosa, Gomesa ranifera, Gomesa cornigera, and Gomesa riograndensis), a horticulturally important, albeit scarcely studied orchid genus, were investigated. Pollination biology was studied through fieldwork in Rio Grande do Sul in Southern Brazil during two flowering seasons. Breeding systems were studied through controlled pollinations in cultivated plants. All studied species secrete floral oils through elaiophores and are exclusively pollinated by native, oil‐collecting bees of the Centridini or Tapinotaspidini tribes. Pollinarium reconfiguration after withdrawal, a feature likely promoting cross‐pollination, was recorded in G. cornigera and G. riograndensis. All studied species are pollinator‐dependent and either predominantly or fully self‐incompatible, that is, unable to set fruit following self‐pollination. The used indexes of pollination efficiency consistently scored values below 1, indicating that in all studied species less than one flower is pollinated per pollinarium removed. Accordingly, pollen loss was high, ranging from 40% to 75%. Furthermore, inflorescences in natural populations displayed low fruit sets (below 13%). Gomesa flexuosa presented the highest values of pollinarium removal (36.24%) and deposition (15.34%). Significantly, this is the only studied species bearing a tabula infraestigmatica, a column swelling that bees hold to stabilize themselves while gathering the floral oils. Since pollinators were observed in all studied species spending considerable time (up to 3 min 46 s) and visiting several (up to 19) flowers, we propose that the observed low fruit set is the result of a combination of self‐incompatibility, pollinator‐mediated self‐pollination, and pollen loss.

Microclimate suitability for green and coloured sweet pepper hybrids in open and protected structures in sub-tropical humid climate of West Bengal

A study was undertaken for two consecutive seasons (autumn-winter) to evaluate the performance of three green, red and yellow-fruited sweet pepper hybrids in open field and under two protected structures (50% green shade net house and naturally-ventilated polyhouse) to understand the microclimate suitability for maximizing the productivity of these hybrids under sub-tropical humid climatic condition of eastern India. In this climatic condition, naturally-ventilated polyhouse was most suitable for enhancing fruit yieldof both green and coloured fruited hybrids. Open field condition was not suitable for both yellow and redfruited hybrids. Though green-fruited hybrids could be grown in open field condition, fruit yield was more than double under polyhouse. Shade net house could not be considered as a suitable protected structure for sweet pepper in this climatic condition because of reduced light intensity and high relative humidity inside it causing low fruit set and high incidence of bacterial wilt disease. Maximum/minimum temperature30oC to 33oC / 14oC to 17oC with comparatively reduced light intensity of 35,000 to 55,000 lux, prevention of adverse effect of low night temperature during winter and  60 per cent relative humidity condition during flowering, fruit set and fruit development period inside the naturally ventilated polyhouse were most suitable growing conditions for getting maximum productivity of both green and colour-fruited hybrids of sweet pepper.

Pollinator supplementation mitigates pollination deficits in smallholder avocado (Persea americana Mill.) production systems in Kenya

Avocado (Persea americana Mill.) is a major horticultural crop that relies on insect mediated pollination. In avocado production, a knowledge gap exists as to the importance of insect pollination, especially in East African smallholder farms. In this study, conducted in a leading smallholder avocado production region in Kenya, we assessed the dependence of avocado fruit set on insect pollination and whether current smallholder production systems suffer from a deficit in pollination services. Furthermore, we assessed if supplementation with colonies of the Western honey bee (Apis mellifera L.) to farms mitigated potential pollination deficits. Our results revealed a very high reliance of avocado on insect pollinators, with a significantly lower fruit set observed for self- and wind-pollinated (17.4%) or self-pollinated flowers (6.4%) in comparison with insect-pollinated flowers (89.5%). We found a significant pollination deficit across farms, with hand-pollinated flowers on average producing 20.7% more fruits than non-treated open flowers prior to fruit abortion. This pollination deficit could be compensated by the supplementation of farms with A. mellifera colonies. Our findings suggest that pollination is limiting fruit set in avocado and that A. Mellifera supplementation on farms is a potential option to increase fruit yield.

Strategies in Forestry to Combat Global Climate Change

Populations with little genetic variation are more vulnerable to the arrival of new pests or diseases, pollution, changes of climate and habitat destruction or other catastrophic events. Biological diversity is the best tool to counter environmental changes and combat climate change in uncertain future. Spatial isolation, fragmentation, increased in-breeding, low fruit set in disturbed natural forests necessitates more population sizes to generate enough variability through mutation and recombination's. Planting a diverse array of species and seed sources is a hedge in the face of global climate change. The best plantation strategy is to maintain diversity, breed for generalists, and deploy intimate mixtures of seed sources or progeny-tested families. Flowering time and seed maturation in plants could be altered in the scenario of climate change; so, should be understood and taken care off. In the era of climate change, conservation of forest genetic resources and their management is necessary to maintain required biodiversity to combat climate change. Seed banking is also a tool in combating the loss of global plant diversity.

BASF with very strong second quarter supported by higher prices and volumes: Surface Technologies

Avocado (Persea americana Mill.) is a major horticultural crop that relies on insect mediated pollination. In avocado production, a knowledge gap exists as to the importance of insect pollination, especially in East African smallholder farms. In this study, conducted in a leading smallholder avocado production region in Kenya, we assessed the dependence of avocado fruit set on insect pollination and whether current smallholder production systems suffer from a deficit in pollination services. Furthermore, we assessed if supplementation with colonies of the Western honey bee (Apis mellifera L.) to farms mitigated potential pollination deficits. Our results revealed a very high reliance of avocado on insect pollinators, with a significantly lower fruit set observed for self- and wind-pollinated (17.4%) or self-pollinated flowers (6.4%) in comparison with insect-pollinated flowers (89.5%). We found a significant pollination deficit across farms, with hand-pollinated flowers on average producing 20.7% more fruits than non-treated open flowers prior to fruit abortion. This pollination deficit could be compensated by the supplementation of farms with A. mellifera colonies. Our findings suggest that pollination is limiting fruit set in avocado and that A. Mellifera supplementation on farms is a potential option to increase fruit yield.

Intensity and mode of Lindera melissifolia reproduction are affected by flooding and light availability.

We studied the impact of flooding and light availability gradients on sexual and asexual reproduction in Lindera melissifolia (Walt.) Blume, an endangered shrub found in floodplain forests of the Mississippi Alluvial Valley (MAV), USA. A water impoundment facility was used to control the duration of soil flooding (0, 45, or 90 days), and shade houses were used to control light availability (high = 72%, intermediate = 33%, or low = 2% of ambient light) received by L. melissifolia established on native soil of the MAV. Sexual reproductive intensity, as measured by inflorescence bud count, fruit set, and drupe production, was greatest in the absence of soil flooding. Ninety days of soil flooding in the year prior to anthesis decreased inflorescence bud counts, and 45 days of soil flooding in the year of anthesis lessened fruit set and drupe production. Inflorescence bud development was the greatest in environments of intermediate light, decreased in high‐light environments, and was absent in low light environments. But low fruit set diminished drupe production in intermediate light environments as compared to high light environments. Asexual reproduction, as measured by development of new ramets, was greatest in the absence of soil flooding and where plants were grown in high or intermediate light. Plants exhibited plasticity in reproductive mode such that soil flooding increased the relative importance of asexual reproduction. The high light environment was most favorable to sexual reproduction, and reproductive mode transitioned to exclusively asexual in the low light environment. Our results raise several implications important to active management for the conservation of this imperiled plant.

High fruit setting rate without male participation: A case study of obligate apomixis in Rhomboda tokioi (Orchidaceae)

Seed production is the key factor for maintaining plant population renewal and development. Because of pollination limitations and other factors, orchids, especially rewardless ones, generally have low fruit set rates. In Rhomboda tokioi, however, the natural fruit setting rate is very high, more than 90%. Common reasons for such a high natural fruit setting rate include high pollinator efficiency, autonomous selfing, seed formation through apomixis and so on. To test these possibilities, we carried out field observations, morphological examinations, and breeding system experiments. The results showed no migration of pollinia into or out of flowers and suggested that the structure of the floral organs hinder autonomous selfing. Interestingly, the fruit setting rate of this orchid was still higher than 90% when the gynostemium was removed prior to flowering. Additionally, after hand pollination, the pollen tube stopped growing at a late stage and could not enter the ovule, indicating the seeds were produced by obligate apomixis. Morphological experiments showed that a megasporocyte first forms a chain tetrad and then develops into a mature embryo sac, while the embryo of the offspring developed from unfertilized egg cells. More interestingly, the offspring had the same number of chromosomes as the female parent. According to the existing theory of apomixis, we can infer that the reproductive model of R. tokioi is Allium-type apomixis.

Fruit Set in Avocado: Pollen Limitation, Pollen Load Size, and Selective Fruit Abortion

Avocado is a woody perennial fruit crop originating in Central America and Mexico domesticated and cultivated in the Americas since pre-Columbian times, currently cultivated in subtropical, tropical, and Mediterranean climates worldwide, with increasing importance in international trade. Avocado shows an exuberant flower production that, however, results in a very low fruit set reflected in a massive abscission of flowers and fruitlets. Several factors are involved in this behavior, and, in this work, we have focused on pollination limitation. The results obtained show that pollen deposition takes place at the female and male stages during the avocado flowering season and that the percentage of flowers with pollen on the stigma varies along the flowering season, probably due to changes in temperature that affect not only the floral behavior but also pollinator activity. However, no embryo or endosperm development took place when pollination occurred during the male flowering phase. Thus, the low number of pollen grains landing on the stigmas of female stage flowers observed under natural pollination conditions might not be enough to ensure a good yield. The production of an excess of flowers and subsequent flower drop of most of the flowers provides the opportunity of a selective fruitlet drop depending on the genotype of the embryo since fruits derived from outcrossing showed higher chances of reaching maturity. Moreover, an important competition for resources occurs among developing fruits and new vegetative growth, conferring importance to the time of flower fertilization for effective fruit set.

Effect of growth regulators on African pear (Dacryodes Edulis (G. don) H.J. Lam) flowering, fruiting and fruit set

Many tropical fruit trees flower profusely. Majority produce many fruits at the onset. Most of these fruits if not all, may be aborted. African pear is a typical example. In this research, four fruit abortion-prevention treatments were evaluated namely: Distilled water, Urea, Giberellin and Coconut water. Floral and pomological parameters were compared and averaged over a period of three consecutive years. At fruit maturity, number of fruits/inflorescence/branches was counted and compared to test the effects of the various treatments on fruit retention and enhancing its pomological characteristics. The design was Randomized complete block design. Regression and correlation in Statgraphic 16.0 software package were used to compare the effects of the various treatments on flowering, fruiting and fruit retention. Application of growth regulators significantly enhanced flowering, fruiting and fruit set. The best fruit retention of 76.56 % was obtained by Coconut water which was however, not significantly (P=0.05) different from 72.75% fruit set obtained by Giberellin. Distilled water gave the lowest fruit-set of 21.41 % which was however significantly (P=0.05) different from 66.48% obtained by Urea. There was no significant difference (P=0.05) in some of the pomological attributes measured. Application of Giberellin and Coconut water significantly (P=0.05) enhanced flowering, fruiting and fruitset in African pear.

Integrated SMRT Technology with UMI RNA-Seq Reveals the Hub Genes in Stamen Petalody in Camellia oleifera

Male sterility caused by stamen petalody is a key factor for a low fruit set rate and a low yield of Camellia oleifera but can serve as a useful genetic tool because it eliminates the need for artificial emasculation. However, its molecular regulation mechanism still remains unclear. In this study, transcriptome was sequenced and analyzed on two types of bud materials, stamen petalody mutants and normal materials, at six stages of stamen development based on integrated single-molecule real-time (SMRT) technology with unique molecular identifiers (UMI) and RNA-seq technology to identify the hub genes responsible for stamen petalody in C. oleifera. The results show that a large number of alternative splicing events were identified in the transcriptome. A co-expression network analysis of MADSs and all the differentially expressed genes between the mutant stamens and the normal materials showed that four MADS transcription factor genes, CoSEP3.1, CoAGL6, CoSEP3.2, and CoAP3, were predicted to be the hub genes responsible for stamen petalody. Among these four, the expression patterns of CoAGL6 and CoSEP3.2 were consistently high in the mutant samples, but relatively low in the normal samples at six stages, while the patterns of CoSEP3.1 and CoAP3 were initially low in mutants and then were upregulated during development but remained relatively high in the normal materials. Furthermore, the genes with high connectivity to the hub genes showed significantly different expression patterns between the mutant stamens and the normal materials at different stages. qRT-PCR results showed a similar expression pattern of the hub genes in the RNA-seq. These results lay a solid foundation for the directive breeding of C. oleifera varieties and provide references for the genetic breeding of ornamental Camellia varieties.

Low fruit set in an endangered tree: pollination by exotic bumblebees and pollen resource for relictual native bees

Low fruit set in an endangered tree: pollination by exotic bumblebees and pollen resource for relictual native bees

A primary study of breeding system of Ziziphus jujuba var. spinosa

Ziziphus jujuba var. spinosa has been used as a windbreak and for soil conservation and water retention. Previous studies focused on pharmacological effects and extraction of chemical components in this species, and very few explored the breeding system. The present study combined the analysis of floral morphology, behavior of flower visitors, and artificial pollination to reveal reproductive characteristics of the species. Its flowers are characterized by dichogamy, herkogamy, and stamen movement, which are evolutionary adaptations to its breeding system. There were more than 40 species of visiting insects, mainly Hymenoptera and Diptera, and the characteristics of dichogamous and herkogamous flower adapted to the visiting insects. The breeding system is outcrossing, partially self-compatible, and demand for pollinators. The fruit setting rate after natural pollination was 2%. Geitonogamy and xenogamy did not significantly increase the fruit setting rate, indicating that the low fruit setting rate was not due to pollen limitation by likely caused by resource limitation or fruit consumption. The fruit setting rate of zero in emasculated and in naturally and hand self-pollinated individuals suggested the absence of apomixis and spontaneous self-pollination. The above results can be utilized in studies on evolution and cultivation of Z. jujuba var. spinosa.

Reproductive biology of Mimosa microphylla and Albizia julibrissin (Fabaceae: Caesalpinioideae) with a new explanation for the evolution of polyads, restricted stigmas, and polycarpelly in the mimosoid clade1

Although it is yet to be conclusively established, floral features of many legumes of the mimosoid clade suggest the existence of a highly wasteful late-acting form of genetic self-incompatibility. We evaluated the role this may have played in the evolution of aggregated pollen, restricted stigmas, and polycarpelly in these plants by first investigating the reproductive biology of two species from the southeastern United States: Mimosa microphylla and Albizia julibrissin. Insights gained from detailed study of their reproductive biology informed a wider, critical review of reproductive characters in other members of the clade. Descriptions of the flowers and inflorescences of the two southeastern U.S. species fail to define clearly the functional situation, including that both species are andromonoecious. Pollen of M. microphylla is released as tetrads, whereas polyads of 16 pollen grains characterize A. julibrissin. Diameters of the cup-like stigmas are constrained so that typically only one or a few tetrads or one polyad will fit. These features are consistent with a syndrome involving, in its fullest manifestation, low fruit set, restriction of stigmatic surfaces, pollen aggregation, reduction of ovule number, and polycarpelly. We interpret all of these unusual features as adaptations to circumvent a highly wasteful (of pollen and ovules) form of late-acting self-incompatibility in which rejection of self-pollen occurs in the ovary. These adaptations reduce the likelihood of a mixed load of self- and cross-pollen being delivered. Enhanced efficiency of pollen transfer may also contribute to the evolution of aggregated pollen, but this explanation fails to account for the other unusual features of this syndrome.

Hormonal and carbohydrate control of fruit set in avocado ‘Lamb Hass’. A question of the type of inflorescence?

The avocado tree (Persea americana Mill.) has two types of shoots, indeterminate, which maintain vegetative development from an apical bud, and determinate, which do not have vegetative growth. Indeterminate shoots set fewer fruits than determinate ones, and significantly hasten physiological fruitlet abscission. The competition between vegetative and flower development is accepted as the most reasonable hypothesis to explain the differences. However, our results show that from anthesis until fruit set flowers of indeterminate inflorescences, both those remaining on the tree and those abscised, had a higher sucrose and C6 carbohydrate content than flowers of determinate ones and no differences between them were found for C7 carbohydrates, which disagrees with this hypothesis, and indicates that factors other than carbohydrate content are responsible for fruit set in avocado.At anthesis and fruit set stage, gibberellin and cytokinin concentrations (mainly GA1 and tZ, respectively) were significantly higher in flowers of determinate inflorescences than in those of indeterminate ones, indicating their higher ability to set.We conclude that fruit set is hormonally regulated in avocado, irrespective of vegetative growth. The lower fruit set of the indeterminate inflorescences does not depend on the competition for photosynthates due to the apical vegetative growth, since C6 and C7 carbohydrate availability is enough to ensure fruit set, but on their lower content of GA1 and tZ.

Effects of Grape NAC Transcription Factor DRL1 on Floral Organogenesis in Tobacco

Grape (Vitis vinifera) is among the world’s most important fruit crops and is a commonly used woody plant for genomics and post-genomics research. NAC transcription factors play central roles in plant growth and development, floral organ morphogenesis, and responses to biological stress. It is therefore important to identify key transcription factors from grape and clarify their mechanisms of action to generate genetic resources for grape molecular improvement. Our research group previously cloned a NAC transcription factor from V. vinifera ‘Yatomi Rosa’ [drought and leaf roll gene 1 (DRL1)] and demonstrated that it caused dwarfing of tobacco (Nicotiana benthamiana) plants when overexpressed. In the present work, we demonstrate that overexpression of DRL1 in transgenic tobacco delays flowering time and markedly reduces pollen viability. Furthermore, crosses between male DRL1 transgenic tobacco and female wild-type tobacco exhibit substantially lower fruit set, fruit and seed weights, fruit and seed shape indices, and seed germination rates than selfed wild-type plants or crosses with a transgenic female parent. DLR1 overexpression strongly influences flowering time and reproduction in transgenic tobacco, primarily through its effects on pollen development. These results provide a foundation for further functional characterization of DLR1 in grape.

Branched Secondary Alcohol Ethoxylate, Ammonium Thiosulfate, Calcium polysulfides-thiosulfate, and Fish Oil Effects on Blossom Thinning, Fruit Set and Quality of Peaches and Nectarines

Abstract Total crop load has an inverse relationship with fruit size, while larger fruit size is often demanded by the peach and nectarine markets. Hand-thinning is extremely expensive, and thus, crop load adjustment, using blossom thinners is a crucial practice to ensure production of commercially acceptable fruit size and yield efficiency in stone fruit. In this study, the influence of branched secondary alcohol ethoxylate (Tergitol TMN-6), ammonium thiosulfate (ATS), Crocker Fish Oil, (FO) and a mixture of calcium polysulfides and thiosulfate (lime sulfur) on fruit set and quality attributes in peaches (Prunus persica) and nectarines (P. persica var. nectarina) were studied. All blossom thinners reduced fruit set in 'Summer Lady' peach in both 2016 and 2017. Fruit sets in 'Summer Lady' peach trees with a double application of Tergitol TMN-6 at the rate of 7.5 or 10 mL.L-1, each rate applied at 40% and 80% bloom, were lower than those receiving the same rates of this chemical only at 80% bloom, but they were similar to those receiving a single Tergitol TMN-6 spray at 15 mL.L-1 at 80% or 100% bloom. 'Summer Lady' peach trees receiving Fish Oil at 20 mL.L-1 plus lime sulfur at 25 mL.L-1, once at 40% bloom and again at 80% bloom had lower fruit set as compared to Un-treated Control but the fruit set was higher than those with any Tergitol-TMN-6 spray. Tergitol TMN-6 at 12m.L-1 at 100% bloom or 10 mL.L-1 all stages of bloom reduced fruit set in 'Zee Lady and Snow Giant' peaches. Total yield was proportional to the severity of thinning and final fruit weight. In 'Snow Giant' peach, trees receiving Tergitol TMN-6 at all concentrations and blossom stages had significantly higher fruit weight as compared to the trees of Un-treated Control. Applications of Tergitol TMN-6 at all concentrations at 80% bloom reduced fruit set in 'Red Globe' and 'Elberta' peaches in Utah comparing with Un-treated Control. Overall, it is concluded that efficacy of blossom thinners depends on the rate of thinners, cultivar and stage of bloom development.

Effects of Plant Growth Regulators on Fruit Set and Yield of Taiwan Morus macroura

In recent years, it is a common phenomenon that Taiwan Morus macroura has low fruit set in different mulberry planting areas that occurred popularly in China. This study aims to study the effects of plant growth regulators on fruit set and quality of Taiwan Morus macroura. Field experiments were carried out to investigate ten plant growth regulators, treated with 3 concentration gradients. The result shows that six plant growth regulators had better fruit preservation effect, the yield of mulberry which treated with plant growth regulators were significantly higher than that of control groups. To reserve fruit in fruit mulberry production, 85% 2,4-DNa SP with 400000~600000 dilution, 99.9% Boron fertilizer SL with 1500~2500 dilution, Amino acid soluble fertilizer SP with 35000 dilution, 80% DA-6 SL with 50000 dilution, 0.03% NAA SL with 50000 dilution and 8% Chlorophenoxyacetic acid sodium salt SP with 3000~6000 dilution are the best from the standpoint of food safety and economics.

Population structure and reproductive biology of peyote (Lophophora diffusa, Cactaceae), a threatened species with pollen limitation1,2

Threatened species frequently have a J-shaped population structure, which indicates a reduction in seed set and poor or nonexistent recruitment. Altered population structures may be due to disrupted demographic processes that result in low reproductive success or small population size. Peyote—Lophophora diffusa Croizat (Bravo)—is a rare, threatened cactus species that is subject to overexploitation because of psychedelic tourism and medicinal and religious uses that decrease its effective population size. We analyzed peyote population structure and identified attributes of its reproductive biology that may limit population persistence. The population's size structure (based on plant size in square centimeters) was determined by census in 2014 and 2015 (n = 420 individuals). Determination of the breeding system of peyote was based on floral morphology and evaluation of herkogamy, dichogamy, and pollen/ovule ratio, and controlled pollination experiments were used to determine the outcrossing rate and whether the species was pollen limited. Additionally, behavior and frequency of floral visitors were recorded to establish the pollinator guild. Peyote's population structure showed the presence of seedlings, juveniles, and adults in both years, indicating some recruitment and low adult mortality. Flowers were herkogamous, homogamous, and diurnal, with a 2-day longevity and high pollen/ovule ratios. These floral traits suggest that peyote is xenogamous, and pollination experiments indicated that it is a facultative outcrossing species, which needs pollinators to set fruit. The time of pistil receptivity coincided with the maximum activity of floral visitors (small solitary bees and small beetles) searching for floral rewards. Evidence indicates that peyote has an outcrossing system with partial self-incompatibility and is pollen limited. Positive factors, such as moderate seedling recruitment, a similar population structure during the two study periods, and a large number of reproductive individuals (close to 50%), indicate natural regeneration and increase the likelihood of population persistence. However, low fruit set and strong dependence upon efficient pollinators reduce reproductive success and increase species vulnerability.