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East African diploid cooking bananas, commonly called Mchare, are a staple crop for millions of subsistence farmers in Tanzania, particularly in the Pangani region in northern Tanzania. Several pathogens constrain Mchare production significantly and threaten food security. Sources of resistance to these pathogens have been identified; however, partial male and female sterility impedes successful resistance introgression, complicating the breeding process. Mchare cultivars are also the only known surviving representatives of a diploid banana subgroup that contributed unreduced gametes to many of the most widely grown and successful triploid dessert bananas (‘Cavendish’, ‘Gros-Michel’, ‘Silk’, and ‘Prata’). As such, they represent an essential intermediate step in the conventional improvement of bananas worldwide. We assess the amount and viability of pollen among Mchare and wild genotypes to identify the most fertile Mchare cultivars that can be used in conventional banana improvement. Pollen was collected from 14 banana genotypes for quantification and viability testing over 7 months, and the optimal time for pollen collection was determined to be 0800 HR. Significant variation among banana genotypes in terms of both overall pollen production and percentage of pollen viability was observed. The wild-type bananas ‘Calcutta 4’ (International Musa Germplasm Transit Center (ITC) 0249] and ‘Borneo’ (ITC0253) had the greatest overall pollen production (> 31,000 pollen grains/anther) and viability (~74%), whereas ‘Ijihu Inkundu’ (ITC1460; Mchare genotype) was the least productive (almost completely sterile), with an average pollen production of a few hundred grains per anther and a viability of 7%. There were significant differences among months in terms of pollen viability, with the greatest average viability observed in May, April, and February (> 51%), and the lowest average pollen viability in July (41%). Significant differences were observed among the Mchare genotypes, with ‘Huti-White’, ‘Huti green bell’ (ITC1559), and ‘Mchare Laini’ consistently producing more substantial amounts of total pollen and an overall more significant proportion of viable pollen. This information is vital to improve Mchare bananas and the global breeding of dessert bananas. The choice of Mchare banana used in improvement programs could affect fertility and the likelihood of breeding success. [ABSTRACT FROM AUTHOR]

Reproductive barriers are the single largest impediment in breeding of Solanum aethiopicum (Shum and Gilo cultivars). Knowledge of these barriers is important for prudent germplasm utilization and genetic improvement of the species. This study investigated compatibility barriers between S. aethiopicum and its relatives. A randomized complete block design and a full diallel mating method were used to evaluate crossability and floral traits of six genotypes of four different species (S. aethiopicum, S. macrocarpon, S. anguivi and S. incanum) across two seasons. Parameters assessed were petal opening time, stigma receptivity, anther dehiscence, pollen quantity, pollen viability and crossing success. Most flowers for all parental genotypes were opened by 08:00 am. Mean number of open flowers was higher (12 ± 6) for S. aethiopicum Shum (N11) and lowest (n = 3 ± 1) for S. macrocarpon (E12; (p < 0.001), with other genotypes being intermediate. Stigma receptivity differed (p < 0.001) among genotypes and seasons and was highest for N11 at 3.31 ± 1.32 and lowest for S. incanum (In1) at 2.24 ± 1.27; other genotypes were intermediate. All genotypes possessed high pollen viability (µ > 80%) though species differed (p < 0.01). All genotypes exhibited self-compatibility to varying degrees with N11 showing the highest fruit success (67.9 ± 15.6%), seeds per fruit (82 ± 51), and F1 germination rate (79 ± 18%). Interspecific crosses using S. macrocarpon, S. anguivi and S. incanum as females showed poor or no fruit and seed. N11 (S. aethiopicum Shum) was the top performer as a female; crosses with S. macrocarpon (N11xE12) showed highest fruit success (65.9 ± 26.5), with S. anguivi (N11xA1) showing the highest seed set (n = 56 ± 34) and S. incanum (N11xIN1) showing the highest F1 germination (64 ± 19). The F1 intraspecific cross between S. aethiopicum Shum (N4) and S. aethiopicum Gilo (G4) did not germinate. Female parent functioning may be a key feature for the failure of interspecific crosses where S. aethiopicum is a donor as observed by the unilateral incompatibility. [ABSTRACT FROM AUTHOR]

Brinjal hybrid seed production primarily utilizes the seed-to-seed method. Optimal results require synchronized stigma receptivity and pollen viability, timing of emasculation and pollination along with the appropriate quantity of pollen on the female parent's stigma. With this perspective, the research was carried out, employing the parents of the GJBH 4 brinjal hybrid. The study involved 18 experiments, considering two emasculation options namely emasculation on same day as flower opening, emasculation on a day prior to flower opening, three pollination times namely 8-9 am, 9-10 am and 10-11 am and three cross-pollination ratios namely two female flowers per male flower, four female flowers per male flower, six female flowers per male flower. The results revealed that for better hybrid seed yield, emasculation on the day prior to flower opening, pollination between 9-10 am and using one male flower to pollinate four female flowers could be adopted. [ABSTRACT FROM AUTHOR]

The production of melons (Cucumis melo L.) in greenhouses relies on pollination. Extreme temperature and insufficient light reduce not only flower visitation by pollinators but also pollen viability, resulting in inefficient pollination. In this study, we investigated the effects of forchlorfenuron [(N-(2-chloro-4-pyridyl)-N0-phenylurea (CPPU)] on the fruit setting and growth of oriental melons (C. melo L. var. makuwa Makino). The primary objective was to devise a new strategy for the management of oriental melons. Treatment with 5 mg·L21 CPPU a day before flowering (T1), on the day of flowering (T2), and a day after flowering (T3) increased the fruit setting rate (by 20.1% to 30%) in melons subjected to artificial pollination (AP) or no pollination (NP) compared with the rate in those subjected to only artificial pollination without CPPU (CK). CPPU treatment induced unfertilized seeds; in addition, a tendency toward parthenocarpy was noted. The highest fruit setting rate (~95%) was noted in plants subjected to the following treatments: AP+T1 and NP+T3. The rates of abnormal fruit formation decreased from 45.2% of CK group to 9.4% in plants subjected to AP+T1 and to 19.4% in those subjected to NP+T3. Elevated exogenous concentrations of CPPU markedly increased fruit weight. Plants subjected to NP+10 mg·L21 CPPU bore the heaviest fruits (541.0 g), which were heavier than those borne by plants subjected to AP+10 mg·L21 CPPU. CPPU treatment reduced the fruit cavity ratio in a concentration-dependent manner from 47.3% to 33.6% and increased the pulp thickness from 1.5 to 2.5 cm. Notably, supplementary CPPU treatment exerted no significant effects on fruit traits. Regarding taste, inconsistent results were obtained for sugar accumulation. Although the content of cucurbitacin B increased immediately after the initial CPPU treatment, it markedly decreased after 15 days of CPPU treatment. Therefore, mature melons did not have a bitter taste. [ABSTRACT FROM AUTHOR]

Fig types such as "Smyrna" and "San Pedro" require pollination (called caprification in fig cultivation) to produce a commercial crop, based on the crop and pollination characteristics of figs. Caprification is the process of hanging caprifig (male fig) fruits on female fig trees to ensure the transfer of pollen from the female fig to the caprifig by a wasp (Blastophaga psenes) that lives within the caprifig. It is necessary to extend the caprification period by using caprifig genotypes that ripen at different times, as female fig fruits ripen gradually. However, as caprifigs may not be continuously available for pollinating female figs, storing suitable caprifigs is necessary. The aim of this study was to assess changes in Blastophaga psenes, the duration of Blastophaga's exit, and the viability of pollen from caprifigs of different genotypes (16 08 05, 16 08 09, 16 08 10, 16 09 10, and 16 ZF 08) stored for caprification. These stored caprifig genotypes were subsequently used for pollination three times at 8-day intervals, after which their impact on the set and quality of the edible fig fruits was evaluated. According to the average data, at the end of storage, the least B. psenes loss was obtained from the 16 08 05 (61.03%) genotype, and the highest was obtained from the 16 09 10 (67.00%) genotype. Pollen germination tended to increase with the storage of caprifig fruits, but this increase was not linear. After storage, the 16 08 09 and 16 09 10 genotypes exhibited greater pollen germination. The highest fruit set and quality were obtained when the 16 08 09 and 16 09 10 genotypes were used as pollen sources. Furthermore, since the 16 08 10 genotype is the latest ripening caprifig genotype, it has been determined that it can pollinate late-ripening "Bursa Siyahı" fruits. Principal component and path analysis demonstrated that pollen viability and germination rate were crucial in selecting caprifig genotypes for fruit set and quality. [ABSTRACT FROM AUTHOR]

Ipomoea triloba L., an annual twining herb, is considered an alien invasive species and is distributed all around the globe including tropical Asia. It affects the yield of various economically important crops. Studies on floral phenology and reproductive biology are fundamental for the development of management strategies and the conservation of plants. Hence, we investigated the phenology, floral biology, pollen viability, stigma receptivity, pollination mechanism, and reproductive success of I. triloba at two different locations in one of the global biodiversity hotspots. Floral anthesis was diurnal, starting at 6:30 a.m. and lasting until 7:00 a.m. Pollen viability and stigma receptivity were found to coincide, thus suggesting the species was homogamous. The flowers were mostly visited and pollinated by sweat bees (Halictidae), blue‐banded bees (Amegilla sp.), flies (Mesembrius sp.), and butterflies (Appias olferna, Pelopidas agna, and Zizina otis). Further, the pollinator visitation frequency showed a moderately positive correlation with the number of open flowers in both study populations. The plant produced fruits in the absence of pollinators in self‐pollination treatments, indicating a self‐compatible breeding system and dependency on insect pollination for reproductive success. Further, pollen supplementation significantly enhanced the fruit setting and mean seed per fruit at both study sites, suggesting pollen limitation. Additionally, pollen production and pollen/ovule ratio also indicated the facultative autogamous breeding system in I. triloba. Overall, these reproductive characteristics such as mixed mating systems and generalist insect visitation may allow the invasive I. triloba to establish new populations from low numbers of propagules. [ABSTRACT FROM AUTHOR]

Flowers of most Piperales do not reward pollinators. However, a few mutualistic pollination relationships have been proposed among the perianth-bearing species. To test the hypothesis of a mutualistic relationship between Prosopanche and beetle pollinators, we studied the pollination biology of three species (P. americana , P. bonacinae , P. panguanensis). For all three species, we recorded flower visitors and flower volatile organic compounds (VOCSs). In addition, for P. americana we investigated flower phases, thermogenesis, visitors' behaviour, and viability of transported pollen. Using a behavioural experiment, we identified the role of flower heat and fragrance in pollinator attraction. We recorded Neopocadius nitiduloides and Lasiodactylus sp. sap beetles (Nitidulidae) as main pollinators and Hydnorobius hydnorae and H. helleri weevils (Belidae) as occasional pollinators. Thermogenic female flowers heat up to 8°C above the ambient temperature. Flowers only trap the small-sized sap beetles. Methyl-3-methyl-2-butenoate dominated the VOC profile. This was a powerful attractant for sap beetles in controlled bioassays. We conclude that pollination in Prosopanche is mutualistic. This was observed through a pollinator-size-based access limit to the stigmatic chamber and a strong olfactory attractant. Mutualism in Prosopanche therefore contrasts with that of most perianth-bearing Piperales, suggesting it is a novel pollination relationship in early-diverging angiosperms. [ABSTRACT FROM AUTHOR]

Ottelia cordata is a kind of rare and endangered submerged plant that grows in freshwater wetlands in northern Hainan Island, from Haikou to Wenchang in China. This species is known for its beautiful appearance and the distinct “flower river” landscape, which makes it a high ornamental value. With the intensification of human activities, the habitat of O. cordata has been sharply reduced and fragmented, leading to its endangerment. In order to explore the reproductive characteristics and reproductive laws of O. cordata, the flower morphology, sex ratio, pollen viability, stigma receptivity, reflectance spectrum, pollen limitation and apomixis, and the types and behaviors of pollinators in O. cordata were analyzed. That is, the pollination biology of O. cordata were studied for its further in-situ and ex-situ conservation. The results were as follows:(1)The flowers were dioecism, and the sex ratio of female and male individuals was about 1:2; the morphologies of male and female flowers were similar, and the female flowers were slightly larger than the male.(2) O. cordata had high pollen viability and stigma receptivity in budding and blooming phases.(3)Apis cerana was the main pollinator of Ottelia cordata, which visited male flowers more frequently than female flowers, with higher pollination efficiency.(4)The distance between the color loci of pistils and stamens was significantly higher than the discrimination threshold of Apis cerana.(5)The fruit setting percentage under natural pollination was similar to that under artificial pollination(95.29% and 98.42%, respectively), and there was no apomixis and low pollen limitation in the natural population of Ottelia cordata. In conclusion, the deceptive pollination of O. cordata simulated by both sexes is imperfect. Pollinators can visually distinguish female and male flowers. However, the large number of male flowers of O. cordata attracted many insects to visit flowers, which increases the probability of “mistake” pollination and is enough for the reproductive needs of female flowers. Therefore, future ex-situ conservation and artificial population restoration should pay more attention to population size, sex ratio and the number of local pollinators. [ABSTRACT FROM AUTHOR]

Climate change alters environmental conditions in ways that directly and indirectly affect plants. Flowering plants, for example, modify reproductive allocation in response to heat and drought stress, and such changes can in turn affect pollinator visitation and, ultimately, plant reproduction. Although the individual effects of warming and drought on plant reproductive allocation are well known, these factors may interact to influence reproduction. Here, we conducted a fully crossed temperature by irrigation manipulation in squash (Cucurbita pepo) to test how temperature and soil moisture variation affect pollinator‐mediated reproduction. To tease apart the direct and indirect effects of temperature and soil moisture, we compared hand‐pollinated plants to bee‐pollinated plants and restricted bee foraging (i.e., pollen transfer) to one experimental group per day. Temperature and soil‐moisture limitation acted independently of one another: warming decreased flower size and increased pollen production, whereas the effects of soil‐moisture limitation were uniformly inhibitory. While treatments did not change squash bee (Xenoglossa spp.) behavior, floral visitation by the honey bee (Apis mellifera) increased with temperature in male flowers and decreased with soil moisture in female flowers. Pollen deposition by bees was independent of plant soil moisture, yet reducing soil moisture increased pollen limitation. This result stemmed at least in part from the effects of soil‐moisture limitation on pollen viability; seed set declined with increasing deposition of fluorescent pigment (a proxy for pollen) from plants experiencing decreased soil moisture. These findings suggest that the transfer of lower‐quality pollen from plants experiencing soil‐moisture limitation led to drought‐induced pollen limitation. Similar effects may occur in a wide variety of flowering plant species as climate warming and drought increasingly impact animal‐pollinated systems. [ABSTRACT FROM AUTHOR]

Pollen allelopathy positively or negatively influences the fertilization of plants and has great significance from ecological perspectives. The release of allelochemicals from foreign pollen grains on the stigmatic surface obstructs the processes of fertilisation, seed establishment, tube formation, stigma receptivity, and pollen germination. So far, pollen allelopathy has received little attention and still a growing topic of ecological studies. Therefore, a literature review was undertaken to provide the valuable information regarding the ecological and reproductive implications of pollen allelopathy, heterospecific pollen transfer mechanisms of allelopathic anemophilous and entomophilous plants, and to shed light on the biochemistry and mode of action of allelochemicals. The majority of entomophilous plants share pollinators within communities, and heterospecific pollen transfer by both anemophilous and entomophilous plants causes a reduction in their reproductive success, like pollen germination, tube development, ovule maturation and seed set. For detailed study of pollen allelopathy, a few factors should be considered like metrological parameters, distance travelled by pollen, pollen viability, and stigma receptivity during foreign pollen deposition. A thorough understanding of the biochemical and enzymatic processes that occur after foreign pollen is deposited on the native stigma will open up new perspectives on plant reproduction. Pollen allelochemicals, which have important significance as biocontrol agents for the maintenance of agroecosystems, need to be identified and characterised. The ecological aspects of pollen allelopathy may be well understood with the help of field studies. [ABSTRACT FROM AUTHOR]

• Zygotic quiescence prolongation is the main reason for the long reproductive cycle of Berchemia. sinica. • The young fruits of Berchemia. sinica entered dormancy in the form of "overwintering complex", and it is the result of convergent evolution. • Androdioecy in Berchemia is reported for the first time. More than two-thirds of the species in Berchemia exhibit remarkable reproductive phenology, characterized by prolonged fruit ripening and the occurrence of overlapping fruit ripening and flowering. However, the underlying reasons for these phenomena remain unknown. Therefore, this study employed routine paraffin section technology, histochemical technique and scanning electron microscopy to investigate embryo sac development, differences between male and hermaphroditic flowers, as well as the overwintering strategy in Berchemia sinica. The findings of this study revealed a significant reduction in pollen viability and the number of pollen grains per flower in hermaphroditic compared to male flowers. Following fertilization, the ovary of hermaphroditic flowers does not undergo significant enlargement but gradually enters the state of zygotic quiescence. Zygotic quiescence prolongation is the main reason for the long reproductive cycle of B. sinica , and it takes approximately 14 months for the entire cycle from flower bud differentiation to fruit ripening to complete. Long reproductive cycle and complex overwintering mechanism exhibited by B. sinica resemble those seen in species belonging to Betulaceae, Fagaceae, Tapisciaceae, and Theaceae, suggesting convergent evolution during Earth's glacial period resulted in similar adaptive structures among these groups delayed fruit ripening leads to overlap between current year's flowers with previous year's fruits. The trade-off between flower and fruit for reproductive resources may have driven evolutionary transition from ancestral hermaphroditism towards androdioecy in Berchemia. [ABSTRACT FROM AUTHOR]

The effects of individually applied heat or drought stress on cotton's pollen fertility, and consequently on yield formation, have been extensively studied. In contrast, the effects of their compound stress have received minimal attention. To address this, a pond experiment was conducted using a cotton cultivar, Yuzaomian 9110 and the treatments consisted of control (CK), drought stress (DS), elevated temperature (ET), and the combination of elevated temperature and drought stress (ET+DS). Results revealed that ET+DS resulted in larger decreases in cottonseed number per boll and boll weight than DS or ET, which were attributed to the lower pollen fertility under the combined stress compared to either single stress. The decreases in pollen fertility under all stress conditions were further associated with disturbances in anther carbohydrate and energy metabolism. Pollen viability was negatively correlated with sucrose content, but was positively correlated with starch and ATP contents under different conditions. Specifically, DS increased anther sucrose content by increasing sucrose phosphate synthetase (SPS) activity to enhance sucrose synthesis, and by decreasing sucrose synthetase (SuSy) and acid/alkaline INV activities to restrict sucrose hydrolysis to fructose and glucose. Similar to DS, ET+DS increased anther sucrose content, which was attributed to the restricted sucrose hydrolysis, due to the reduced activities of SuSy and acid/alkaline INV, and acid INV activity even was lower under ET+DS than DS. However, ET enhanced acid invertase (INV) activity to promote sucrose hydrolysis, and down-regulated the expression of GhSUT3A/D (sucrose transporter gene), GhSUT4 (sucrose transporter gene) and GhSWEET55 (encoding Sugars Will Eventually Be Exported Transporters proteins) to inhibit sucrose transport into anthers, so the anther sucrose content was decreased. Furthermore, ET, DS and ET+DS treatments significantly decreased starch synthesis by down-regulating the expression of GhAGP , GhGBSS and GhSSS ; however, the ET+DS treatment had a lower GhSSS expression than any single stress, which further inhibited amylopectin synthesis and resulted in lower anther starch content compared to CK and either of the individual stresses. In addition, significant reductions were observed in anther pyruvate content under all stress conditions, which inhibited the ATP production in the tricarboxylic acid cycle. Nevertheless, different pathways were involved in the response of energy metabolism to single and combined stresses. In particular, single ET or DS down-regulated GhHK1 and GhPK to decrease pyruvate formation, while the downregulation of GhHK1 and GhPGK were responsible for the decreased pyruvate content under combined stress. Additionally, either single stress resulted in the upregulation and downregulation of GhATP α subunit and GhATP β subunit of ATP synthase, respectively, the opposite was observed under the condition of combined stress, indicating that differential response mechanisms of ATP synthase are activated between the combined stress and any individual stresses. All these confirmed that elevated temperature combined with drought stress have a unique effect on carbohydrate and energy metabolism of anthers, resulting in larger decreases in pollen fertility, cottonseed number per boll and boll weight than either of the stresses alone. • Compound stress had lower seed boll−1 and boll weight due to lower pollen fertility. • Pollen viability was negatively related to sucrose content, but positively related to starch and ATP contents. • Compound stress further disrupted carbohydrate metabolism, showing as higher sucrose and lower starch. • Compound stress had lower ATP to further disrupt energy metabolism. [ABSTRACT FROM AUTHOR]

• The flower visitation and seed set of S. daiguii in the TNFP was scarcely affected by biotic factors. • Seed set in the ZEFR was affected by serious pollen limitation. • Presence of fountains and increased humidity reduced the pollinator types, visitation frequency, and natural seed set of TNFP. • Higher daily temperatures reduced the pollinator abundance and visitation frequency in ZEFR. Salvia constitutes one of the largest genera in the Lamiaceae, with approximately 1,000 species found worldwide, and is recognized for its high ornamental and medicinal value. Salvia daiguii is a multipurpose perennial herb that grows on cliffs in the Zhangjiajie City, Hunan Province, China. Nevertheless, the pollination biology of vulnerable plants on cliffs, specifically the effects of abiotic factors on flower visitation and seed set, remains poorly understood. In this study, we observed the effects of biotic factors: flowering phenology and flower characteristics, flower longevity, nectar volume and concentration, pollen viability and stigma receptivity, pollinator visitation frequency, pollen remaining and deposition, and breeding systems, as well as abiotic factors: habitat fountain, temperature, and humidity, on the pollination and seed production of S. daiguii in two populations in Zhangjiajie City. The pollination biology results reveal that S. daiguii has a mixed mating system that depends on pollinators. The flower visitation and seed set of S. daiguii in the absence of natural fountain areas in Tianmenshan National Forest Park was scarcely affected by biotic factors. However, we observed a significant reduction in pollinator types, visitation frequency, and natural seed set of this population owing to abiotic factors, including the presence of a fountain habitat and increased humidity. Further, seed set in the Zhangjiaxi Ecological Forest Reserve was affected by both biotic (serious pollen limitation) and abiotic (higher population temperature) factors. We considered that pollinators types, flower visitation frequency, and natural seed set are vulnerable to the influence of ecological factors in fragmented habitats. Our results reveal the mechanisms contributing to the endangerment of species exemplified by S. daiguii and underscore the significance of conservation efforts for the sustainable use of other endangered species. [ABSTRACT FROM AUTHOR]

• Aids breeding initiatives and medicinal plant species preservation. • Supports forest conservation and management. • Facilitates human-facilitated cross-pollination for fruit/seed set cross-pollination. • Crucial for evolutionary ecological study, conservation strategies, and habitat restoration. Understanding a species' reproductive biology, which encompasses floral biology, pollination biology, and breeding system, is necessary for the restoration of endangered plant species. Buchanania lanzan is a vulnerable evergreen tree in IUCN Red Data Book due to excessive deforestation and over-exploitation. Light and scanning electron microscopy and histochemical analysis were used to study floral and pollination biology. Experiments were conducted to study floral and pollination biology, including pollen viability, stigma receptivity, and pollen-pistil interactions. Bisexual, pentamerous, complete yellowish-white flowers have an annual growth of 11 months and are arranged in terminal and axillary panicles. Anthers dehisce between 10.30 and noon, 9–10 h after anthesis. Stigmas were receptive at the time of anther dehiscence and remained receptive for two days. The flowers contain sucrose-rich nectar and emit a mild scent to attract visitors, including Musca domestica, Apis cerena indica, and black ants. None of these visitors appeared to be an effective pollinator. The results of pollination trials showed that the species outcrosses with low levels of selfing. Cross-pollinated flowers had a higher percentage of fruit sets (74.4 %) compared to self-pollinated (43.4 %) and open (3 %). The index of self-incompatibility (ISI) indicates partial self-incompatibility. Due to the probable loss of pollinators or the lack of efficient pollinators, the natural population of B. lanzan has not yet been restored. To achieve the required fruit or seed set cross-pollination facilitated by humans would be a feasible technique. Therefore, to prevent the extinction of this species, human management is required in terms of cross-pollination. As a result, the scientific knowledge produced by the current study may prove helpful in various breeding initiatives and the preservation of this medicinal plant species. Further, this knowledge forms the basis for taking measures for the conservation and management of forests. [ABSTRACT FROM AUTHOR]