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Heat stress negatively affects pollination, fertilization, and consequently, the development of strawberry fruits. It was proved that foliar application of titanium organic complex improved pollination and fertilization processes of some plant species, which resulted in better fruit development. Therefore, a three-year experiment was designed to determine the effect of the titanium organic complex on pollination and fertilization processes and consequently on fruit development of three remontant strawberry cultivars grown under canopies, under conditions of high temperature. The experiment demonstrated that high temperature disrupted the flowering physiology of strawberry. Under such conditions, the viability and germination of pollen as well as the receptivity of stigma were significantly reduced. The application of titanium organic complex during flowering had a beneficial effect on the pollination and fertilization processes of strawberries. Plants treated with the titanium organic complex were characterized by higher pollen viability, better pollen germination, a higher number of achenes in fruit, and a higher weight of individual fruit, compared to the not treated plants. The obtained results suggest that application of titanium organic complex during flowering may alleviate the stress caused by high temperature and contribute to the improvement of the quantity and quality of a crop. [ABSTRACT FROM AUTHOR]

Pollen is the first choice of germplasm curator, geneticist, breeder and physiologist for conservation and crop improvement programs. A pollen palynological attributes and pollen germination study of Lilium longiflorum cv. 'Pavia' was conducted using scanning electron microscope (SEM). Various morphological characteristics were studied. The results showed that pollens were much alike in ultramorphology with elliptical to ellipsoidal shape, reticulate exine and single germination ditch. The pollen viability was tested by the wet room method with 3 dyes: Acetocarmine, TTC, Lugol's iodine. 49.66% pollen viability was recorded with Acetocarmine dye, which suggested acetocarmine stain can be used as a quick test method for pollen viability. The pollen germination ability was examined at set intervals, thereby establishing the dynamics of this process for 72 hours. Pollens collected just 1 h after anthesis were recorded with the highest germination (85%) compared to pollen harvested before or one day after. The suitable medium for pollen germination was 3% sucrose and 15% PEG, which was recorded with the highest pollen germination (95%) after 72 h of inoculation. Understanding evolutionary ecology and the sterility problem and designing hybridization programmes in cross-breeding necessitates a thorough understanding of pollen morphology and viability. Pollen ultra-morphology traits could be useful in determining the evolutionary relationship of lilies. [ABSTRACT FROM AUTHOR]

Programmed cell death (PCD) is an important factor to reduces the viability of plant germplasm after cryopreservation. However, the pathways by which PCD occurs is not fully understood. To investigate whether there is a mitochondrial pathway for pollen PCD after cryopreservation, the pollen of Paeonia lactiflora two cultivars with different PCD levels after cryopreservation was used as test material and the changes of mitochondrial calcium ions (Ca2+), structure, function and their relationship with PCD were compared. The results showed that compared with fresh pollen, the PCD of 'Feng Huang Nie Pan' was significantly reduced after cryopreservation. Their mitochondrial Ca2+ content decreased by 74.27%, mitochondrial permeability transition pore (MPTP) opening reduced by 25.41%, mitochondrial membrane potential slightly decreased by 5.02%, cardiolipin oxidation decreased by 65.31%, and oxygen consumption remained stable, with a slightly ATP production increase. On the contrary, compared with fresh pollen, 'Zi Feng Chao Yang' showed severe PCD after cryopreservation. The decline in mitochondrial Ca2+-ATPase activity led to an accumulation of excessive Ca2+ within mitochondria, triggering widespread opening of MPTP, significantly affecting mitochondrial respiration and energy synthesis. These results suggest the mitochondrial pathway of PCD exists in pollen cryopreservation. • After cryopreservation, the imbalance of mitochondrial homeostasis leads to the occurrence of PCD. • The opening of MPTP plays an indispensable role in the occurrence of PCD during pollen cryopreservation. • Mitochondrial Ca2+ signaling is a pivotal regulatory factor in PCD occurrence. • For the first time established the measurement method for respiratory metabolism (OCR and ECAR) of pollen. [ABSTRACT FROM AUTHOR]

Background. Studying the reproductive ability of black currant cultivars after long-term cryopreservation of their pollen in liquid nitrogen is very important for plant diversity conservation and for the effectiveness of breeding efforts.Materials and methods. Five black currant cultivars served as the material for the research. The viability of black currant pollen after cryopreservation in liquid nitrogen was analyzed. Pollen viability was tested on an artificial medium containing 10% of sucrose and 0.8% of agar. The viability of pollen was tested on the black currant collection at Pushkin and Pavlovsk Laboratories of VIR. The cultivar ‘Andreevskaya’ (k-15630) was pollinated with pollen stored for one year in liquid nitrogen (–196°C) as well as with fresh pollen (control test).Results and conclusion. After 12 months of conservation under ultralow temperatures there was a change in the level of pollen viability depending on the genotype: it varied from 10.4% (cv. ‘Pozdnyaya poslevoennaya’, k-7654) to 50.4% (cv. ‘Kriviai’, k-42517), while its mean value was 0.9% higher than the mean initial viability. The fruit setting rate in the control option was 81.3–94.2%. When pollinated with pollen kept in liquid nitrogen for one year, the fruit setting rate varied from 69.2% (‘Kacha’, k-44185) to 93.3% (‘Belorusochka’, k-41978); the remaining cultivars (‘Pozdnyaya poslevoennaya’; ‘Chereshneva’, k-42481; and ‘Kriviai’) demonstrated intermediate values of this indicator, i.e., the reproductive ability of pollen after cryopreservation was high even despite its low viability. As for the fruit weight, no differences were shown by cvs. ‘Kacha’, ‘Chereshneva’ and ‘Kriviai’ in both pollination options, while this indicator in cvs. ‘Belorusochka’ and ‘Pozdnyaya poslevoennaya’ was lower than the control by 0.31 and 0.24 g, respectively.

Triticum aestivum is a self-pollinated species with a high proportion of cleistogamous flowers constituting a blockade for out-crossing. Therefore, male parent characteristics are the main goal in the production of hybrid wheat seeds. In a two-year study conducted in Lublin (Poland), the features of flowering biology that can be relevant for the cross-pollination ability of the pollen donor were investigated in winter wheat genotypes. In particular, the anther extrusion capacity, pollen production at the anther and spike levels, and pollen biological value were examined. The pollen production in the anthers was established using an electronic particle counter. The pollen biological value was assessed based on viability (acetocarmine staining) and in vitro pollen germination (raffinose medium) assays. The inter-genotype effect for anther extrusion was significantly correlated to the post-anthesis filament length. The anther extrusion for the individual genotypes fluctuated significantly between the years of the study; however, the interaction with meteorological factors was not assessed. The considerable inter-genotype variability in the pollen donor capability for cross-pollination was highly significantly correlated with the proportion of extruded anthers rather than pollen production, indicating that anther extrusion plays a more important role in the contribution to the final amount of pollen available for cross pollination. The pollen viability determined by staining was high (between 97.5% and 100%), while the in vitro pollen germination varied substantially among the genotypes (between 17.3% and 87.8%). The pollen dispersal ability for cross-pollination in wheat can be improved mainly by increasing the proportion of extruded anthers; however, the pollen production and pollen germination potential cannot be ignored if complete characterization of the ideal male idiotype is to be achieved. [Display omitted] • Proportion of extruded anthers plays substantial role for cross-pollination in wheat. • Anther extrusion is mainly related to the post-anthesis filament length. • Pollen production and pollen germination are important for the ideal male idiotype. [ABSTRACT FROM AUTHOR]

Reproductive-stage heat stress (RSHS) poses a major constraint to cereal crop production by damaging main plant reproductive structures and hampering reproductive processes, including pollen and stigma viability, pollination, fertilization, grain setting and grain filling. Despite this well-recognized fact, research on crop heat stress (HS) is relatively recent compared to other abiotic stresses, such as drought and salinity, and in particular, RSHS studies in cereals are considerably few in comparison with seedling-stage and vegetative-stage-centered studies. Meanwhile, climate change-exacerbated HS, independently or synergistically with drought, will have huge implications on crop performance and future global food security. Fortunately, due to their sedentary nature, crop plants have evolved complex and diverse transient and long-term mechanisms to perceive, transduce, respond and adapt to HS at the molecular, cell, physiological and whole plant levels. Therefore, uncovering the molecular and physiological mechanisms governing plant response and tolerance to RSHS facilitates the designing of effective strategies to improve HS tolerance in cereal crops. In this review, we update our understanding of several aspects of RSHS in cereals, particularly impacts on physiological processes and yield; HS signal perception and transduction; and transcriptional regulation by heat shock factors and heat stress-responsive genes. We also discuss the epigenetic, post-translational modification and HS memory mechanisms modulating plant HS tolerance. Moreover, we offer a critical set of strategies (encompassing genomics and plant breeding, transgenesis, omics and agronomy) that could accelerate the development of RSHS-resilient cereal crop cultivars. We underline that a judicious combination of all of these strategies offers the best foot forward in RSHS tolerance improvement in cereals. Further, we highlight critical shortcomings to RSHS tolerance investigations in cereals and propositions for their circumvention, as well as some knowledge gaps, which should guide future research priorities. Overall, our review furthers our understanding of HS tolerance in plants and supports the rational designing of RSHS-tolerant cereal crop cultivars for the warming climate. [ABSTRACT FROM AUTHOR]

A study was conducted to investigate the effect of different storage periods and temperatures on pollen viability in vitro and in vivo in plum genotypes 'Valerija', 'Čačanska Lepotica' and 'Valjevka'. In vitro pollen viability was tested at day 0 (fresh dry pollen) and after 3, 6, 9 and 12 months of storage at four different temperatures (4, −20, −80 and −196 °C), and in vivo after 12 months of storage at distinct temperatures. In vitro germination and fluorescein diacetate (FDA) staining methods were used to test pollen viability, while aniline blue staining was used for observing in vivo pollen tube growth. Fresh pollen germination and viability ranged from 42.35 to 63.79% ('Valjevka' and 'Čačanska Lepotica', respectively) and 54.58 to 62.15%, ('Valjevka' and 'Valerija', respectively). With storage at 4 °C, pollen viability and germination decreased over the period, with the lowest value after 12 months of storage. Pollen germination and viability for the other storage temperatures (−20, −80 and −196 °C) were higher than 30% by the end of the 12 months. Pollination using pollen stored at 4 °C showed that pollen tube growth mostly ended in the lower part of the style. With the other storage temperatures, pollen tube growth was similar, ranging between 50 and 100% of the pistils with pollen tubes penetrated into the nucellus of the ovule in the genotype 'Čačanska Lepotica'. The results of these findings will have implications for plum pollen breeding and conservation. [ABSTRACT FROM AUTHOR]

Alfalfa (Medicago sativa L.) is an important forage in intercropping or rotation ecosystem, and shading is the principal limiting factor for its growth under the crop or forest. Agronomic studies showed that shading would systematically reduce the biomass of alfalfa. However, little is known about the reproduction of alfalfa under shading conditions. In order to study the effect of shading on the reproductive characteristics of alfalfa, two alfalfa cultivars ("Victoria" and "Eureka") were used to study the effect of shading levels (full light, 56.4% shade, and 78.7% shade) on alfalfa flowering phenology, pollen viability, stigma receptivity, and seed quality. Results showed that shading delayed flowering phenology, shortened the flowering stage, faded the flower colors, and significantly reduced pollen viability, stigma receptivity, the number of flowers, quantity, and quality of seeds. Under shading conditions, seed yield per plant was obviously positively correlated with germination potential, germination rate, pollen viability, and 1,000-seed weight. The number of flower buds, pollen viability, 1,000-seed weight, and germination rate had the greatest positive direct impact on seed yield per plant. Our findings suggested that delayed flowering and reducing reproduction growth were important strategies for alfalfa to cope with shading and pollen viability was the key bottleneck for the success of alfalfa reproduction under shading. However, given that alfalfa is a perennial vegetative-harvest forage, delaying flowering in a weak light environment was beneficial to maintain the high aboveground biomass of alfalfa. Therefore, this should be taken into account when breeding alfalfa cultivars suitable for intercropping. Future research should further reveal the genetic and molecular mechanism of delayed flowering regulating the accumulation and distribution of assimilates between vegetative and reproductive organs of alfalfa under shading, so as to provide a theoretical basis for breeding of shade-tolerant alfalfa cultivars. [ABSTRACT FROM AUTHOR]

Pollen pistil interaction studies were carried out in six sunnhemp genotypes. Pollen viability percentage of the six genotypes ranged from 0.0 to 93.5% and pollen germination ranged from 0.0 to 84.0% at four different floral stages starting from bud to opening of a flower. The viable pollen grains were present at the later three stages of flower for globose type anthers, while the pollen grains were viable at the later two floral stages for heart shaped anthers. Stigma receptivity was high to very high during S3 and S4 stages. Artificial self-pollination and sib pollination with a mixture of pollen grains were carried out and in vivo pollen tube growth in the style was investigated using fluorescence microscopy. In self-pollinated pistils, eight hours after pollination, callose wall development was seen around the nucellus cell. However, under sib pollinated pistil, eight hours after pollination, pollen tube penetrated into embryo sac of an ovule. The formation of callose in self-fertilized pistil prevented fertilization and seed set. But sib pollinated flowers were fertilized normally and a seed set could be observed. The investigation proved the existence of selfincompatibility. [ABSTRACT FROM AUTHOR]

Roses are one of the most highly produced and purchased ornamental plants worldwide. Procurement and preservation of pollen is essential for the production of diverse rose varieties. In this study, we analyzed pollen management conditions, such as the pollen collection stage, drying time, and storage temperature, to determine optimal conditions for rose pollen management. Pollens were stored under different conditions and the pollen vitality and germination rate were investigated through an optical microscope. The vitality of pollen was an essential factor for rose breeding and depended on the storage conditions. Collecting pollen in the seventh flowering stage resulted in a relatively higher pollen yield. Drying the flower for 5 h after the anther opened improved pollen germination. The germination rate of freshly collected pollen was similar to that of pollen stored at temperatures between −20 °C and −72 °C for up to 30 days, indicating the efficacy of pollen storage at sub-zero temperatures. Since the rate of fruiting increases when pollination is performed three times, considering the time and cost of breeding, it is appropriate to pollinate three times to increase the number of seeds. This study provides an efficient pollen management method to collect and store pollen for breeding. [ABSTRACT FROM AUTHOR]

Orchids are fascinating for many reasons: their reproductive strategies, their pollination systems and the various morphological adaptations they have evolved, including the presence of pollen grains agglomerated into two masses, called pollinia, which form a structure known as a pollinarium. After withdrawal from a flower, the pollinarium undergoes a bending movement such that the pollen masses become correctly orientated to strike the stigma. We evaluated the duration of pollinator visits to inflorescences and the effects of temperature on pollinaria reconfiguration in eight orchid species in order to analyze the effects of increasing air temperature on the changes in bending time, and thus on geitonogamy levels. The impact of temperature on insect behavior was not assessed because our priority was to understand the effects of temperature on the process of pollinaria reconfiguration. All the examined species showed natural reconfiguration times that were 1.7–3.0 times longer than the pollinator residency times. A higher temperature showed a reduction in bending time regardless of the species tested. However, the bending time was never shorter than the residence time of the insects on the flower. Our data showed that high temperatures had a limited effect on the pollinarium reconfiguration time, thus indicating that high temperatures had a limited effect on folding compared to the effect that it had on the viability of the pollen. [ABSTRACT FROM AUTHOR]

Climate change is being felt in all vineyards around the world, opening up new perspectives for regions with a growing winemaking industry. In this study, 11 hybrid grapevines grown in cold climates were assessed in terms of flowering biology and pollination efficiency. The flowers were evaluated for the number of anthers and pollen grains in the flower; pollen viability and pollen grain size, the number of ovules in the ovary, and, consequently, the size and the weight of berries and the number of seeds in the berries were also analyzed. The flowers of Vitis vinifera L. usually have 5 stamens and 5 petals in their structure; this number for hybrid varieties ranged from 4 to 7, and in the case of the variety 'Seyval Blanc', it was 4 to 11 stamen and petals. Pollen grain size varied and ranged from 17.01 to 22.25 μm, while pollen grain pro-duction in flowers ranged from 5073 to 34,976 grain, which was calculated using a Bürker hemocytometer. The number of ovules in the ovary for the cultivars in question was highly variable, ranging from 3 to 7. One of the most important factors affecting flower pollination is stigma receptivity. Stigma receptivity appeared when the cap starts to fall off and disappeared at the browning of the cap. In connection with climatic changes, grapevine production is expanding to cool-climate countries. The aim of this study was to expand our knowledge about the flower morphology of 11 hybrid grapevine varieties most commonly cultivated in Poland. Knowledge of the flowering process can be important for improving yield and its quality. [ABSTRACT FROM AUTHOR]

A key step in the pre-breeding stage of plant breeding is the selection of cultivars with desirable characteristics for use as parents to develop new crop varieties. With the development of technology, numerous laboratory techniques have emerged as key tools for breeding programs to save time and resources. For these reasons, the aim of this review was to describe techniques based on cytological and cytogenetic studies that are feasible for the selection of parents during the pre-breeding stage. Among the cytological techniques addressed in this review are: pollen viability and quality, stigmatic receptivity to know how long the stigma is receptive, and pollen tube growth to study incompatibility events. Another key step in pre-breeding is to determine the chromosomal number of the parents, which is possible by different techniques of classical cytogenetics (studies during mitosis and meiosis) and molecular cytogenetics (flow cytometry, Fluorescent in situ Hybridization and Genomic in situ Hybridization) that are discussed in this review. [ABSTRACT FROM AUTHOR]

The reproductive traits of alien plants are an important factor contributing to their successful invasion. Xanthium italicum (Compositae) is a widespread invasive weed in China. In this study, we compared the reproductive traits of this species with those of its native relative X. sibiricum, with the aim to provide a scientific basis for characterizing the invasion mechanisms of X. italicum. The traits compared were flowering phenology, stigma receptivity, pollen viability, pollination agent, male and female inflorescence functions, and breeding system, based on field investigations, experimental observations, and controlled pollination treatments. Xanthium italicum presented a longer flowering period and stigma receptivity stage, higher pollen viability, higher average number of male and female inflorescences per plant, and larger amount of pollen, which increase the probability of stigma pollination and seed setting, than X. sibiricum. Although both species are wind pollinated, the pollen grains of X. italicum are more widely dispersed than those of X. sibiricum. Moreover, whilst X. sibiricum is strictly wind pollinated, X. italicum is characterized by insect pollination. The dual pollination mechanism and longer pollination distance of X. italicum constitute advantageous pollination strategies of this invasive plant. Controlled pollination studies revealed that the breeding systems of the two plants are mixed, including both outcrossing and selfing, although the amount of seeds produced by X. italicum was higher than that by X. sibiricum. Overall, compared with the native species, the successful invasion of X. italicum can be attributed to the differences in reproductive strategies. [ABSTRACT FROM AUTHOR]

Fragmented ash populations due to ash dieback may lead to a limited gene flow and pollination success. Therefore, the viability of ash pollen plays a major role for the survival of the species. The extent to which the long-distance transport of pollen affects pollen viability was investigated with experiments in a climate chamber using ash pollen samples from a seed orchard in Emmendingen, Germany. Furthermore, experiments with a volumetric pollen trap were conducted. A suitable storage temperature for ash pollen was determined by using four viability tests; TTC test, pollen germination, Alexander's stain and Acetocarmine. An optimization of the germination medium was performed. We found a strong influence of prevailing temperatures on pollen viability, which decreased faster under warmer conditions. At moderate temperatures, viable pollen could still be observed after 28 days. Thus, a possible successful pollination can also be associated to long-range transported pollen. Storage experiments showed that pollen viability could be maintained longer at temperatures of −20 °C and −80 °C than at 4 °C. In particular, the TTC test has proven to be suitable for determining viability. Therefore, properly stored pollen can be used for breeding programs to support the survival of Fraxinus excelsior. [ABSTRACT FROM AUTHOR]

Chloroxylon swietenia DC. (Rutaceae) is widely used in folk medicine and provides a commercial timber. In the present study, phenological events such as flowering and fruiting phenology, pollinator visitation, anthesis, pollen viability, and pollen tube germination tests were analyzed in 11 populations, in Tamil Nadu, India. The number of flowers was recorded as 82.6 ± 1.4 to 162.2 ± 4.2 during flower bud formation and reduced to 25.4 ± 0.5 to 61.8 ± 1.0 at maturity. The number of fruits per twig was 21.0 ± 0.8 to 47.2 ± 0.7 in initial stages and slightly reduced to 16.2 ± 1.8 to 34.6 ± 1.4 at maturation. Sixty-two species of insects were visiting the flowers with bees/ants as effective pollinators. The 2,5-diphenyltetrazolium bromide assay revealed more viable pollen grains in five populations, and fluorescence dye assay revealed maximum viable pollen grains in six populations. In the pollen tube germination test, the 60% sucrose concentration provides significant results, with a high number of germinated pollen grains. Principal component analysis of flowering and fruiting phenology, floral visitors, and pollen viability showed 79.5%, 79.3%, 56.7%, and 41.7% for the first factor, respectively. Our results indicated that C. swietenia depends heavily on pollinators for its reproduction. Hence, there is a need to expand this study to related species which are having agronomic, pharmacological, and economic potential.

• 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]

In order to provide early selection indicators for the breeding of plants used for producing tea seed oil or harvesting tea, we investigated the relationships between flower morphology and fruit yields in tea plants. We analyzed 106 tea varieties to determine the relationships between flower morphological traits and fruit yields. Notably, the homogeneity of flower traits within the same tea plant variety was found to be very high. The average length and width measurements of certain phenotypic traits of tea plants, including pistil length, stamen length, stamen bundle inner width, stamen bundle outer width, and stigma width, were 11.8, 10.9, 2.5, 15.0, 3.7 mm, respectively. In this study, the flower traits that affect fruit yield appear to be related to the difficulty of pollination by insects (e.g., bees), in terms of their contacting the stigma. In 2013, three phenotypic trait variables showed significant effects on yield; namely, the stamen bundle outer width (negative), stigma width (positive), and stigma width minus the stamen bundle inner width (positive). In 2015, only the stamen bundle outer width had a significant negative effect on yield. Regarding pollen viability, in the TTC (2,3,5-triphenyl tetrazolium chloride) staining test, about 84% of the considered tea varieties presented pollen viability exceeding 70%. This indicates that most tea pollen has the ability to germinate normally after contact with the cross-pollinated stigma. The yields of all of the tea varieties exhibited a positively skewed distribution in 2013 and 2015. Although our results indicate that flowers in the anther superior group tend to produce fewer fruits than flowers in the stigma superior group in 2013, in the analysis of the effect of traits on yield, there were no significant differences in the relative positions of stigmas and anthers. In conclusion, we determined that the main trait affecting fruit yield is stamen bundle outer width, while the secondary trait affecting fruit yield is stigma width. However, the efficacy of the stigma width may also be affected by the position of the stigma relative to the anther and the stamen bundle inner width. These two traits have the potential to be used as reference indicators for early selection in future breeding programs.

Caprification is the process of hanging caprifig fruits on edible fig trees to transfer the pollen inside the caprifig to the edible fig via the wasp (Blastophaga psenes) living in the caprifig. It needs to be repeated several times for the proper fruit set of edible figs. The present study was conducted to determine the change in the number of Blastophaga psenes, the duration of Blastophaga’s exit, and pollen viability in case the caprifigs to be used in the caprification process are stored until use. The number of Blastophaga and in vitro pollen viability were tested at day 0 (harvest day) and after 4, 8, 12, 16 and 20 days of storage at three different temperatures (0, 4, and 8 °C). Afterwards, the effect of pollination frequency on the edible fig fruit set and quality was determined by using Blastophaga psenes as a vector in the pollination of stored caprifig fruits, pollinating five times with 4-day intervals and three times with 8-day intervals. Approximately a 50% reduction in the number of B. psenes was detected after 4 (180.22), 12 (174.11) and 16 (192.66) days of caprifigs storage at 0, 4, and 8 °C, respectively. The pollen germination percentage of the caprifigs increased with storage and was higher in those stored at 8 °C (43.96%) and 4 °C (41.70%). The highest fruit set was obtained when the caprifigs stored at 4 °C (76.41%) and 8 °C (71.38%) five times with 4-day intervals were used for pollination. The pollination practice repeated five times with 4-day intervals resulted in a lower proportion of extra-large fruits with a weight of >100 g, a higher proportion of fruits with no or slight ostiole damage and early ripening of fruits. These results suggest that B. psenes and pollen viability can be preserved by storing caprifigs at 4 or 8 °C and that fruit set and fruit characteristics would be positively affected with the use of stored caprifigs in the pollination practice repeated five times with 4-day intervals.

[ Objective] The presnet paper aimed to understand flowering habits and pollen fenility of Pueraria lobata, and provide reference for improving the success rate of P. lobata cross pollination. [ Method] In Longzhou county, Guangxi, the bud development process of P. lobata inflorescences were observed every day after it was formed, marked the inflorescences that were about to open in the full bloom period, continuously observed the blooming process of the flowers and recorded the blooming time and weather conditions of the day. Triphenyl tetrazolium chloride (TIC) staining and 12 -KI staining were used to detect pollen activity of P. lobata at different bud stages ( half stretch period, presentation period, half period and blooming period), and the pollen with the strongest pollen viability was selected to carry out the pollen germination test according to the pollen viability measurement results. [ Result] In Longzhou county, Guangxi, P. lobata began to flower on October 16, reached the flowering stage on October 20, and the last flowering stage was from November 2 to November 5. The flowering time of P. lobata was mainly from 15: 10 to 15 :40 every day, and the flowering powder was affected by the weather conditions. Flowering was early when the weather was clear and the temperatute was high, while flowering was delayed when the temperature was low and cloudy and rainy. The pollen activity of P. lobata in different bud stages ( half stretch period, presentation period, half period and blooming period) detected by 12 -KI staining method were 82. l %,95. 3%,93. 5% and 92. 7%,respectively, which were significantly higher than TIC staining method ( P <0. 05, the same as below), and it was more suitable for the detection of the pollen activity of P. lobata. Most of the anthers of the P. lobata flower have already loosened their powder at the beginning of the presentation period, and the stigma was wrapped with large amount. The pollen vitality in the presentation period detected by 12-KI staining was the highest, reaching 95. 3%, which was significantly higher than the other three stages. The pollen quantity and pollen vitality remained at a high level from half stretch period to blooming period. In the medium containing 15 % sucrose, the germination rate of P. lobata pollen was the highest( 36. 23 % ), which was significantly higher than that of the other three sucrose concentrations. [ Conclusion]The 12 -KI staining method can quickly detect the pollen viability of P. lobata. The pollen viability of P. lobata was maintained at a high level from half period to blooming period, and the germination rate was the highest in the medium containing 15% sucrose in sunny weather. 12 -Kl staining method can be used to detect pueraria pollen viability rapidly. Pollen viability of P. lobata remained at a high level from bud opening stage to blooming stage, and pollen at a suitable period could be selected for cross-pollination according to weather conditions to improve the success rate of cross-pollination. [ABSTRACT FROM AUTHOR]

Success artificial pollination with viable pollen is crucial process in the production chain of date palms. This study evaluated the impact of pollen storage temperature and duration, pollination time following spathe cracking, and the hour of daytime on pollen viability, germinability, fruit set and yield of 'Deglet Nour' date palm cultivar. In in vitro tests, fresh pollen showed the maximum viability (96.3%) and germination (85%) but it decreased thereafter upon the storage temperature (28, 4 and −30 °C) and duration (3, 6, 9 and 12 months). In this respect, pollen stored at −30 °C retained highest viability and germinability followed by those stored at 4 and then at 28 °C. In filed experiments, fruit set was 85, 75, 65, and 45% with pollination using fresh pollen, or pollen stored at −30, 4 and 28 °C, respectively. Fruit set was 95%, 75%, and less than 50%, for pollination performed on the same day of spathe cracking, 6 and 12 days later, respectively. The highest fruit set percentage and yield/bunch were obtained with pollination performed between 12.0 pm and 15.0 pm in contrast to 8.0–11.0 am or 16.0–17.0. [ABSTRACT FROM AUTHOR]

Genus Garcinia shows high diversity of sexual systems; most of them are dioecious in nature. The other reported sexual systems of Garcinia include gynodioecious, androdioecious, monoecious, and andromonoecious. Garcinia indica (Thouars) Choisy was reported as facultative apomictic polygamodioecious species. There is a large diversity in floral types. Hence, a detailed study of various floral types found on different types of plants of G. indica and to correlate its functionality with sexual reproduction was undertaken. The study at Kokum Plot, BSSKVV, Dapoli, revealed that the male plants could be categorized into four types – androecious, functional males, andromonoecious, and hermaphrodites. The female plants displayed large variation in number and viability of stamens/staminodes. Each category showed significant difference in phenology, floral morphology and pollen types. In December, the percentage of staminate flowers (79.13 ± 2.93%) in androecious trees was significantly higher than functional males (58.61 ± 8.60%) or andromonoecious trees (56.36 ± 2.77%) (p ≤.01). As female plants started flowering, all male morphotypes bore significantly higher numbers of staminate flowers and carpellate flowers were significantly reduced. Pollen viability was highest in androecious flowers at 90.11 ± 1.10% and lowest at 64.70 ± 2.09% in hermaphrodite trees. Earlier studies reported female flowers bore well-developed female gametophyte, but the embryo development was not observed. Thus, the fruit formation might be apomictic, but in present embryological investigation; more than 60% of female and andromonoecious flowers, a well-developed embryo was formed between 8 and 24 h after anthesis. Thus, the embryo formation might be sexual or apomictic. Floral types favoring sexual reproduction are essential for conservation of highly endemic species. [ABSTRACT FROM AUTHOR]

To test for pollination syndrome and to complement records of foraging visitors of an associate mangrove, Barringtonia racemosa (L.) Spreng., aspects of its floral biology were investigated. Phenology and floral rewards (pollen viability, pollen histochemistry and nectar sugar concentration) were focused on owing to their role in plant-pollinator interaction. During the floral opening at 19:00, pollen viability, lipid presence and nectar sugar concentration were highest at 88.05 ± 0.98%, 80.69 ± 10.51%, and 68.98 ± 1.09% mg flower--1, respectively. Starch presence in pollen was rather low (mean 24.95 ± 14.58%), due to hydrolysis of starch occurring during anthesis. These floral characteristics, which reflected the highest reproductive activity, coincided with nocturnal foraging of previously recorded moth visitors. Although bats were rarely observed in previous studies, nocturnal anthesis complemented with the recorded large amount of sugar in nectar (68.98 ± 1.09% mg flower--1 = 1158 J) might be sufficient to provide the average needs of nocturnally foraging bats. Investigation of floral characteristics to complement observation of floral visitors is highly recommended to give a better understanding of the pollination system. Moreover, this study supports the pollination syndrome concept, emphasizing the need for investigation of the role of floral rewards in plant-pollinator relationships. [ABSTRACT FROM AUTHOR]

While no significant differences in initial ovule number were found among oilseed rape Brassica napus genotypes, there was a large variation in effective ovule number (EON), which determines the final seeds per silique (SPS), a critical component of yield. In this study, we selected 18 oilseed rape Brassica napus genotypes with contrasting nitrogen utilization efficiency (NUtE) to unravel the main factors responsible for different EON and determine the critical period of EON formation under both a field and a pot experiments from 2016–2018. The high NUtE genotypes displayed significantly higher NUtE by 14.3%, along with greater yield per plant (29.4%) and SPS (21.1%) than the low NUtE genotypes. The greater productivity of the high NUtE genotypes was associated with 44.1% higher pollen grain number, 23.5% greater pollen viability, and 39.3% lower ovule abortion rate, compared to the low NUtE genotypes. In addition, the heart stage was the critical ovule development period for delineating the variability of EON among contrasting NUtE oilseed rape Brassica napus genotypes, when the high NUtE genotypes displayed higher silique net photosynthetic rate, surface area, biomass, and RNA expression levels. Taken together, this study indicated the pollen grain number, pollen viability and ovule abortion rate contributed to the final variation in EON and the heart stage was the critical period of determining the EON differences among contrasting NUtE genotypes. Increasing pollen grain number and pollen viability, and decreasing ovule abortion rate before heart stage should be the prerequisite for breeders to improve yield and NUtE of oilseed rape Brassica napus genotypes. [ABSTRACT FROM AUTHOR]

Temperature is the major factor in global warming and strongly influences the success of plant sexual reproduction. Therefore, there is an urgent need to assess the vulnerability of species for breeding and planning effective actions. In this study, effects of different temperatures and storage duration on pollen viability and in vivo pollen tube growth were analysed in Citrus sinensis 'Kozan yerlisi'. The pollens were obtained before anthesis and stored at 10 °C, 20 °C and 30 °C for 1, 2 or 3 days before analysis. The pollen viability decreased with increasing temperatures and storage duration from 61.3% to 5.8%. In vivo pollen germination results showed that for one day storage, the pollen growth rates were similar to the control treatment while storing pollens two or three days differed from the control. Pollen germination after storage at 10 °C was lower and not efficient, while after storage at 30 °C no pollen tube germination at all was seen on the stigma. At the same time, storing pollen in low temperature caused delay in pollen tube germination and pollen tube growth, suggesting that pollen that are stored in low temperatures pass into a dormancy process for three to five days. In conclusion, this study indicated that pollen storage in 30 °C for a long time causes loss of pollination ability while storage in 10 °C causes dormancy in pollen. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the flowering biological characteristics, floral organ characteristics, and pollen morphology of Camellia weiningensis Y.K. Li. These features of adult C. weiningensis plants were observed via light microscopy and scanning electron microscopy (SEM). Pollen viability and stigma receptivity were detected We investigated the possibility of either exogenous ethylene or endogenous ethylene production having an association with the increase in shoot number when nodal explants of Gentiana spp. 'Little Pinkie' were cultured in an in vitro medium supplemented with ethephon (10 mg.L-1). For the first time within an in vitro system, we report the application of laser ethylene detector technology, and optimization of the methodology to quantify concentrations of ethylene (in the part-per-billion range) released from ethephon decomposition within the atmosphere of gas-exchangeable culture vessels including nodal explants. Compared with continuous (continuous measurements on the same replicate of vessels) and repeated (sampling same replicate of vessels every 48 hours) sampling methodologies, the nonrepeated (sampling fresh replicate of vessels every 48 hours) method of measurement of ethylene concentration was more representative of the actual condition within vessels. Although no prior published data exist showing the positive or negative effect of gaseous ethylene in the headspace of culture vessels on bud outgrowth in gentian, our study shows gaseous ethylene in the headspace of culture vessels was not effective in increasing shoot formation in gentian explants cultured in vitro, whereas ethephon supplementation in agar was effective. Plant material in culture vessels did not have a significant effect on ethylene production regardless of the presence or absence of ethephon. Therefore, although ethephon supplementation in the medium produced gaseous ethylene in the headspace, it was unlikely to cause endogenous ethylene production in explants, but it did trigger shoot formation in 'Little Pinkie', perhaps through decomposition to ethylene within the explant tissue, enhancing the internal ethylene level possibly at a locally high concentration. [ABSTRACT FROM AUTHOR]

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

Artificial hybridization in Phaseolus lunatus L. is still little used in genetic improvement programs in Brazil due to the low establishment percentages. This work aimed to evaluate pollen viability and stigma receptivity in different Lima bean genotypes throughout the day. Accessions 'Roxinha -MT' and 'Cana Longa-PB' were used in the experiment. Five flower buds were collected from each genotype at 6:00 a.m., 10:00 a.m., 2:00 p.m., and 6:00 p.m. The stigma receptivity was determined using 3% hydrogen peroxide, whereas pollen viability was determined with 2% acetocarmine colouration. The genotype and time factors acted independently on the percentage of viable and non-viable pollen grains and stigma receptivity. The genotype 'Roxinha' presented 88.54% viable pollen grains, a value 84.27% higher than that of the 'Cana Longa' genotype. This percentage varied as a function of time, with the highest means observed at 6:00 a.m. Stigma receptivity was influenced only by the time of the day, undergoing a great reduction in receptivity, from 88% in the early morning to slightly more than 40% around noon. These results indicate that 6:00 a.m. is the most suitable time to perform artificial crosses in Lima bean plants. [ABSTRACT FROM AUTHOR]

The present study aimed at evaluating the genetic variability of different germplasms and comparative effectiveness of morphological descriptors, floral and reproductive biology of three CPTs of annatto viz.,Tamil Nadu (green fruited), Kerala (red fruited), Karnataka (dark red fruited) at department of Forest Biology and Tree improvement, Forest College and Research Institute, Mettupalayam during 2017-19. A record on sequence of flowering ascends along the latitudes. The sequence of flowering is top to bottom (basipetal) that is the development, maturation or opening from the apex towards the base in the sequence. It commenced from the southern side to the south eastern side. The colour of the flower is whitish pink in Tamil Nadu, moderate pink in Karnataka and dark pink in Kerala and this floral colour polymorphism suggests that pollinators (mainly bumble bees and ants) are the primary selective agents which influence flower colour. The stain I-KI showed 95 % pollen viability and it is found that the viability of the pollen grains decreased after four hours from pollen dehiscence and tricolporate pollen was observed in annatto. The observation on fruit set indicated that bixa plant can have both self- and cross-pollination. Fruit maturity takes place 80 – 95 days counting from the day of pollination to fruit dehiscence. The shape of the fruit resembles rounded oblong pyriform. Maximum seed production was recorded in the red fruited (collected from Karnataka) (113.12 g) plant followed by the dark red fruited plant (Kerala) and the green fruited variant (TN).

Dioecious plants are obligate outcrossers with separate male and female individuals, which can result in decreased seed set with increasing distance between the sexes. Wind pollination is a common correlate of dioecy, yet combined wind and insect pollination (ambophily) could be advantageous in compensating for decreased pollen flow to isolated females. Dioecious, ambophilous gymnosperms Ephedra (Gnetales) secrete pollination drops (PDs) in female cones that capture airborne pollen and attract ants that feed on them. Plant sugary secretions commonly reward ants in exchange for indirect plant defense against herbivores, and more rarely for pollination. We conducted field experiments to investigate whether ants are pollinators and/or plant defenders of South American Ephedra triandra , and whether their contribution to seed set and seed cone protection varies with distance between female and male plants. We quantified pollen flow in the wind and assessed the effectiveness of ants as pollinators by investigating their relative contribution to seed set, and their visitation rate in female plants at increasing distance from the nearest male. Ants accounted for most insect visits to female cones of E. triandra , where they consumed PDs, and pollen load was larger on bigger ants without reduction in pollen viability. While wind pollination was the main contributor to seed set overall, the relative contribution of ants was distance dependent. Ant contribution to seed set was not significant at shorter distances, yet at the farthest distance from the nearest male (23 m), where 20 times less pollen reached females, ants enhanced seed set by 30% compared to plants depending solely on wind pollination. We found no evidence that ants contribute to plant defense by preventing seed cone damage. Our results suggest that, despite their short-range movements, ants can offset pollen limitation in isolated females of wind-pollinated plants with separate sexes. We propose that ants enhance plant reproductive success via targeted delivery of airborne pollen, through frequent contact with ovule tips while consuming PDs. Our study constitutes the first experimental quantification of distance-dependent contribution of ants to pollination and provides a working hypothesis for ambophily in other dioecious plants lacking pollinator reward in male plants. [ABSTRACT FROM AUTHOR]

Background and aims: Paspalum lilloi (Poaceae) is a diploid species, endemic of Iguazú Waterfalls and nearby areas. The reproductive biology and current geographical distribution of this species are poorly known. The aims of this work were to determine the genetic system and to delimit the endemism area and conservation status of the species. M&M: The genetic system was determined by cytoembryological analysis of ovules, viability and in vivo germination of pollen grains, pollen-pistils compatibility, fertility and flow cytometry of single seeds. Herbarium specimens and our collection sites delimited the geographical distribution. Results: Meiotic embryo sacs of Polygonum type were observed in all analyzed ovules. No evidence of apomixis was detected. The mean pollen viability and in vivo pollen germination was 95.2% and 41.8%, respectively. The pollen tube growth in the selfed stigmas was 59.2 ± 6.39 µm / 3h. Seed set in self-pollination was 93.6 % and decreased to 52.7 % when there was heterospecific pollen available. Seeds analyzed by flow cytometric seed screen showed an embryo: endosperm ratio 2:3 indicated a sexual origin. Paspalum lilloi is a reophile and rupicolous species, specialized in fast-moving waters of waterfalls and it is a critically endangered endemism of Iguazu Waterfalls, in South America. Conclusions: P. lilloi is sexual, self-compatible and self-fertile species. Has a highly specialized habitat, which conservation will be a key step to avoid its extinction. [ABSTRACT FROM AUTHOR]

Artificial pollination of vegetable crops necessitates the knowledge of crop's floral biology. In this aspect present investigations were carried out, to gather the information on the floral biology of monoecious (K-75 and UHF-CUC-101) and gynoecious (GYNO-1 and GYNO-2) varieties of cucumber at the Experimental Research Farm, Department of Vegetable Science, Dr. YSPUHF Nauni, Solan (HP) during Kharif, 2016. The experiment was laid out in a RCBD with three replications. The observations were recorded on time of anthesis, dehiscence, pollen viability (%), stigma receptivity and node number bearing first female flower. The experimental results showed that anthesis started at 6AM and completed by 8AM with the maximum anthesis between 6AM to 7AM in monoecious varieties whereas, in gynoecious varieties it was maximum upto 6:00AM in both open and controlled conditions and similar pattern was observed for dehiscence. Dehiscence occurs soon after anthesis. Maximum pollen viability was recorded on the day of anthesis and viability of pollen under refrigerated condition did not decrease as rapidly as it was under room temperature condition with the duration of pollen storage. Maximum stigma receptivity was noticed at anthesis time and pollination during this interval recorded maximum fruit-set. Gynoecious lines were earlier in flowering and fruiting than monoecious varieties. [ABSTRACT FROM AUTHOR]

Date palm is a dioecious fruit tree that permits cross pollination for fruit-setting. The germination of viable pollens to fertilize ovule is influenced by environmental cues such as temperature. The germination and viability of pollen grains collected for pollination purpose also varied with the male pollinizer source and the male spathe opening time. An in vitro study performed to determine the percentage of pollen germination at different temperatures (10, 15, 20, 25 and 30 °C) and germination times (4, 8, 12 and 24 h) taken from different male sources and to identify any variations in the germination and viability of pollen grains collected from spathes opened at different dates (20th February, 1st and 10th March). Pollens from different male sources showed a significant difference regarding germination percentage when incubated at different temperatures and for different germination times. Pollens incubated at 30 (81.07%) and 25°C (78.17%) had the highest germination percentage which decreased to 51.04, 16.23, and 5.90% when incubation temperature dropped to 20, 15, and 10 °C, respectively. Similarly, 71.11% pollens germinated after 4 h of incubation at 30°C, which decreased to 63.26 and 25.40% when incubation temperature decreased to 25 and 20°C, respectively after same time interval. Pollen germination and viability significantly differed when they were collected from spathes opened at three different dates. Early opened spathes had lowest germination (57.58%) and viability percentages (81.19%) than the middle (81.11 and 91.53%) or late (80.71 and 93.05%) opening spathes. It is therefore, concluded that the optimum temperature for date palm pollen grains germination is 25-30°C and at these temperatures maximum pollens germinated within 4 h. Moreover, pollen grains from early opened spathes were less superior compared to the middle or late opening ones. [ABSTRACT FROM AUTHOR]

Studies on the selection of floral traits usually consider pollinators and sometimes herbivores. However, humans also exert selection on floral traits of ornamental plants. We compared the preferences of bumblebees (Bombus terrestris), thrips (Frankliniella occidentalis), and humans for flowers of snapdragon. From a cross of two species, Antirrhinum majus and Antirrhinum linkianum , we selected four Recombinant Inbred Lines (RILs). We characterised scent emission from whole flowers and stamens, pollen content and viability, trichome density, floral shape, size and colour of floral parts. We tested the preferences of bumblebees, thrips, and humans for whole flowers, floral scent bouquets, stamen scent, and individual scent compounds. Humans and bumblebees showed preferences for parental species, whereas thrips preferred RILs. Colour and floral scent, in combination with other floral traits, seem relevant phenotypes for all organisms. Remarkably, visual traits override scent cues for bumblebees, although, scent is an important trait when bumblebees cannot see the flowers, and methyl benzoate was identified as a key attractant for them. The evolutionary trajectory of flowers is the result of multiple floral traits interacting with different organisms with different habits and modes of interaction. [ABSTRACT FROM AUTHOR]

Objective: To explore the influence of biological characteristics on the yield of Amomum villosum Lour. and Amomum longiligulare T. L. Wu, to find an effective pollen viability evaluation method and storage method to solve the problem of the low yield of Amomum plants. Methods: Five germplasm of Amomum plants were used to investigate the effects of the phenological phase, pollen viability, and stigma receptivity on natural and artificial fruit set. Results: Amomum longiligulare T. L. Wu showed late flowering, and its natural pollination rate is higher than that of Amomum villosum Lour. In all germplasm, the artificial pollination rate and fruit setting rate are more than 3 times higher than that under natural conditions. Fruits begin to drop seven days after successful pollination, and the fruit drop is basically stable after one month. The hybridization verification showed that TTC method was simpler and more accurate than in vitro germination method. Optimal storage conditions for pollen are 4°C and high humidity. After 36 h of storage, pollen can still be used for artificial cross-pollination or as hybrid parents. Conclusion: The special biological characteristics are the fundamental reason for the low natural pollination rate of Amomum plants. The accurate measurement method of Amomum plants pollen is the TTC method, and storage at 4°C and high humidity can increase the yield, which was six times that of the natural yield. [ABSTRACT FROM AUTHOR]

Tephrosia purpurea and T. villosa display vegetative growth and sexual reproduction throughout the year. T. purpurea produces resupinate and non-resupinate flowers with an explosive pollination mechanism, while T. villosa produces exclusively non-resupinate flowers with a valvular pollination mechanism. Flower-tripping is essential for the function of pollination mechanism and occurrence of self- or cross-pollination; tripping is effected by wind, rain, temperature, thrips, bees and wasps. Both species are facultatively xenogamous. Empty pods, ill-formed seeds and variation in the number of produced seeds has been attributed to the internal regulation by plants, in order to allow cross-pollinated flowers to produce more seeds and abort selectively the genetically inferior pollen resulting from self-pollination. The low fruit and seed set rates recorded in open-pollinated flowers of both Tephrosia species have been attributed to the presence of untripped flowers, extent of cross-pollination rate, short tenure of pollen viability, number of foraging visits made by pollinating insects, flower closure by the end of the day of anthesis, and availability of energy resources. Both species are autochorous, with short-range seed dispersal. Seeds germinate if the soil has moisture and nutrients but their continued growth and development is largely related to their efficiency in utilizing the available nutrients over other co-occurring seedlings or plants growing simultaneously with them. The plants also sprout from the perennial root stock, usually during rainy season. Therefore, the dual modes of propagation ensure these species' recolonizing of the same habitat and invading new habitats. [ABSTRACT FROM AUTHOR]

[Objective] In order to provide theoretical basis for pollen viability identification, artificial pollination and cross breeding of large- fruited yellow passion fruit, the effects of different culture medium in vitro and storage conditions on pollen germination were analyzed. [ Method] Pollens were collected from newly blooming flowers of large-fruited yellow passion fruit The suitable concentrations of sucrose, boric acid, calcium nitrate and suitable pH for pollen in vitro culture were screened by Li, (5 4) onhogonal design. The effects of sampling time of flowers, storage humidity and temperature on pollen viability were studied by using the most suitable pollen culture medium. The suitable storage condition for pollen of large-fruited yellow passion fruit was determined. [Result] The results of onhogonal test showed that the order of influencing factors on pollen germination rate of large-fruited yellow passion fruit was calcium nitrate > sucrose > boric acid > pH. The optimum medium for pollen germination in vitro was 100. 00 g/L sucrose + 0. 02 g/L boric acid + 0. 40 g/L calcium nitrate, and the medium pH was 5. 0. The pollen germination rate in the optimum medium was 85. 55 % . The pollen germination rate of large-fruited yellow passion fruit was more than 80. 00% when the sampling time was from 11 :30 to 17 :30. The pollen viability was the highest in the third hour ( 16: 30) after flowering, which was significantly higher than the germination rate of pol- lens collected at other times except 13 : 30 and 15 : 30 (P <0. 05, the same as below). The results of storage test showed that, the pollen germination rate of natural air drying on sulfur paper treatment for 3 - 48 hours was significantly higher than that of sealed centrifugation tube storage at room temperature and storage in desiccator on sulfur paper for the same time, and the pollen germination rate of 48 h storage was still 34. 28%. The pollen germination rate was 61. 49% after natural air drying for 5 hours and sealed in centrifugal tube at 4 °C for 24 hours, which was significantly higher than that (55. 22%) after natural air drying for 5 hours and sealed in centrifuge tube at - 20 °C for 24 hours. [Conclusion] The optimum medium for pollen germination in vitro of large-fruited yellow passion fruit is 100. 00 g/L sucrose+ 0. 02 g/L boric acid+ 0. 40 g/L calcium nitrate, and pH is 5. 0. The best storage condition is that the pollens collected on the day are dried naturally for 5 hours and sealed in centrifuge tube at 4 °C [ABSTRACT FROM AUTHOR]

The present investigation was conducted to evaluate the pre-fertilization barriers affecting interspecific hybridization between C. pepo and C. moschata at Punjab Agricultural University, Ludhiana during the year 2018. The different pollen and pistil parameters were compared among genotypes of both the species. The non-significant differences were recorded for pollen viability (87.60 to 91.26%), pollen germination (50.08 to 66.60%) and stigma receptivity among all the evaluated genotypes. However, significant variations were observed for the in vitro pollen tube growth and flower style length. C. pepo genotypes possessed the shorter pollen tubes (480.73 to 625.61 pm) and style length (12.00 to 14.00 cm) in comparison to larger pollen tubes (603.32 to 1588.18 pm) and style length (12.50 to 20.00 mm) of C. moschata, which accounted the failure of interspecific crosses. The fertilization of larger style length genotypes of C. moschata with shorter pollen tubes of C. pepo resulted the limited success in hybridization, whereas the reciprocal crosses were more successful. In addition, the pollen tube and flower style length were positively and significantly correlated with each other (r= 0.918), suggesting that these might be the major contributing factors involved in the present hybridization study. These findings provide new insights for the development of methods to overcome reproductive barriers. [ABSTRACT FROM AUTHOR]

Globalization has drastically reduced the number of autochthon apple cultivars in the Serbian market and most of them have nearly disappeared; however, some of these cultivars, such as Petrovača, Budimka, Kolačara Pozna, and Kožara, have extraordinary quality, good pomological characteristics, and pest and disease resistance. The present study was conducted to develop a protocol for the storage of pollen for further use in the conservation and breeding of these cultivars. Viability and germination of the mature pollen were tested in vitro , at four storage temperatures (20, 4, −20, and −80°C), right after harvest or 1, 2, 3, 4, 5, and 6 months after storage. Differences in fresh pollen viability and germination between cultivars were statistically significant and ranged from 60 to 88% and 59 to 98%, respectively. Fresh pollen of cv. Budimka showed the highest viability and germination in comparison with other cultivars, especially cv. Kožara. Pollen viability and germination decreased over the storage period, and it was the lowest after 6 months of storage at room temperature in all tested cultivars. Storage at 4°C prolonged the pollen viability and germinability of 1–5 fold, depending on the cultivar and treatment duration; however, the pollen longevity of all cultivars was significantly extended when stored at −20 or −80°C. After 6 months, pollen of cv. Budimka stored at −20 and −80°C showed 14–15 fold higher germination rates in relation to pollen storage at room temperature for the same period. The results of the present study suggest that the pollen of these apple cultivars could be efficiently maintained at −20°C and could be further used for breeding purposes, e.g., for crossings between cultivars that flower at different times of the year. [ABSTRACT FROM AUTHOR]

To study the effect of boron deficiency and toxicity on the reproductive development and pollen-stigma interaction in sunflower (Helianthus annuus var. Sungold), plants were raised in sand culture under glass house condition till maturity at 0.033 (deficient), 0.33 (sufficient) and 3.3 (toxic) mg B L−1 supply. The effect of deficiency and toxicity of boron on the number, size and weight of inflorescence, anther size, pollen producing capacity (PPC) of an anther and pollen viability were determined. Enzymes peroxidase, acid phosphatase and esterase and protein were cytochemically localized on the stigmatic surface of disk floret. As compared to control plants (0.33 mg B L−1 supply) development of inflorescence was not only delayed but also poor under boron deficiency and toxicity. Pollen grains produced under boron deficiency and toxicity had reduced size with low viability. Histochemical localization of proteins showed marked decrease in concentration on the stigmatic surface of plants receiving deficient and toxic boron supply. Cytochemical localization of peroxidase enzymes on the stigmatic surface showed increased activity whereas a decrease in acid phosphatase and esterase activity was observed suggesting poor pollen stigma interaction under boron stress condition which might be the cause of poor fertilization. [ABSTRACT FROM AUTHOR]

Cross-pollination in cultivated rice (Oryza sativa L.) is rarely reported to exceed 2%. This low crosspollination frequency (CPF) is conducive to successfully maintaining the purity of rice landraces for many generations. We were therefore surprised to notice a dramatic loss of genetic purity in some of the pure line landraces in many farmers' fields. Having ruled out the possibility of mixing of seeds from different varieties, we surmised this rapid loss of genetic purity to be due to a somewhat higher degree of crosspollination, and conducted a carefully designed experiment with suitably chosen pairs of landraces. We report here an unusually high (>81%) CPF seen in a pair of landraces whose flower opening times (FOTs) were coincident. Our control experiment on a pair of landraces with non-overlapping FOTs failed to detect any cross-pollination. This preliminary report suggests that the crucial importance of FOT diversity in landraces in determining CPF has not been recognized in designs of previous reports of crossing experiments, resulting in a severe underestimation of CPF in cultivated rice under natural conditions. [ABSTRACT FROM AUTHOR]

Background: In order to reveal the pollination biological characteristics of Lespedeza davurica, wild L.davurica from eight regions of Shanxi Province was used as test materials to study their floral dynamic, pollen storage and other aspects. Methods: During 2019, the flowering dynamics of wild L. davurica collected from eight regions of Shanxi Province were observed by selecting the better-grown L.davurica. Freshly bloomed flowers were picked, and their pollen was set up for two treatments, dry and undried, for pollen storage experiments. Pollen viability was determined by the TTC (expand for first instance) and MTT (expand for first instance) methods and stigma receptivity was determined by the hydrogen peroxide-benzidine method. Result: The results showed us the following points: the flowers of L. davurica were pale yellow, large and fragrant; it usually opens from the base to the top with distinctly asymmetrical petals; it opens during the day and closes at night; the number of flowers reached its peak between 12:00 and 14:00. After measuring the pollen viability of L. davurica, we found that dry storage at -20ï,°C was the most effective treatment. And with the increase of temperature and decrease of humidity, the pollen viability and stigma receptivity of L. davurica increased continuously and the highest viability value occurs between 12:00 and 14:00. [ABSTRACT FROM AUTHOR]

China is one of the five major distribution regions of Impatiens in the world, with more than 270 species distributed all over the country, especially in limestone areas such as Yunnan, Guizhou and Guangxi. In order to explore pollination ecology of Impatiens uliginosa, we conducted the following experiments: observing the floral traits and floral phenology, measuring the nectar volume and sugar concentration, counting pollen viability, deposition and removal, carrying out pollination treatments and recording floral visitors and their behavior. Results show that the average life span of a single flower is 3.23±0.68 d. The male and female phase lasted for 1.70±0.06 d and 1.53±0.63 d. The amount of nectar per flower is 6.97±0.47 ul and sugar concentration of nectar is 36.58±0.82%, respectively. Stigma is receptive on the first day of anthesis. Pollen viability is strongest on the second day of anthesis. The pollen-ovule ratio (P/O) is 3974.28±105.07. We investigated the contributions of different floral visitors. Bombus sp., Apis dorsata, Lobocla proxima, Ant sp. and Ephydra sp. are diurnal visitors. However, Bombus sp. is the most effective pollinator of I. uliginosa. Pollination treatments indicated that I. uliginosa is self-compatible but completely relies on pollinators for pollination. There is no restriction on pollination in the field and I. uliginosa can avoid inbreeding depression. This study is of great significance to enrich the biological data of pollination and protect the biodiversity of Impatiens. [ABSTRACT FROM AUTHOR]

Apomixis, the asexual formation of embryos and seeds, occurs in approximately 18% of angiosperm families. Melastomataceae exhibits a remarkable number of apomictic species, distributed among different tribes. This mode of reproduction has been elucidated in Miconieae, but remains unclarified for other groups, such as Microlicieae. Although apomixis has been previously described for Microlicieae species, the cytological basis for this phenomenon is entirely unknown in this group. Thus, populations of Microlicia fasciculata and M. polystemma were used in order to (a) investigate the presence of autonomous apomixis; (b) verify if this mode of reproduction leads to polyembryony; and (c) investigate whether apomixis may occur in parallel with the sexual process. We tested these species for autonomous fruit set and polyembryony, and pollen viability, and analyzed pollen tube growth. Anatomical techniques were used to elucidate the micro‐ and megasporogenesis and gametogenesis. The species showed autonomous fruit and seed formation and exhibited polyembryony. Apospory and adventitious embryony were the developmental mechanisms of apomixis in M. fasciculata and M. polystemma, respectively. Both species exhibited low pollen viability. However, some viable pollen, reduced embryo sac formation, natural pollination and pollen tube growth enable sexual reproduction and characterize these species as facultative apomicts. The independence of pollinators for fruit set, uniparental reproduction and the possibility of sexual reproduction, confer reproductive assurance and flexibility, bringing together advantages of sexual and asexual reproduction. In this sense, apomixis may have played an important role in the evolution and diversification of Microlicia, a widely distributed genus in the Brazilian Cerrado. [ABSTRACT FROM AUTHOR]

Parmentiera cereifera Seem. is an endangered species in the family Bignoniaceae. Related to the conservation effort, information about the reproductive biology of this species is very limited. Based on that, the objectives of this study were to provide knowledge about the reproductive properties such as floral biology and breeding system of P. cereifera. The research was conducted at Purwodadi Botanic Garden, from October 2019 to February 2021. Several important aspects of reproductive biology, including flower biology, pollen viability and stigma receptivity, pollen morphology and breeding system were investigated. The viability was tested with TTC (2, 3, 5-triphenly tetrazolium chloride) and stigma reseptivity was tested with hydrogen peroxide. The breeding system was determined based on outcrossing index (OCI) using Cruden's method. The results showed that P. cereifera flower was monoecious, had morphological character that supported nocturnal pollination. Stigma and anthers spatially separated, but there was no temporal separation of stigma receptivity and anther dehiscence. Based on the flower biology, the pollen ornamentation (reticulate type), and the Out-Crossing Index (OCI=4), the breeding system was outcrossing but partially self-compatible, required pollinators (zoophily). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]