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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]

• Comprehensive phenology from the onset of the primordial bud to the senescence phase, is documented for Macrotyloma uniflorum. • Floral organs exhibits ultrastructural variation in Macrotyloma uniflorum. • Macrotyloma uniflorum accessions from Republic of Benin are non-echinate; other accessions exhibit spinuliferous pollen. • There is a positive correlation between days to flowering and most floral traits. • Pollens of Macrotyloma uniflorum are viable during the day. The absence of information on the reproductive biology of some nutritive legumes has been an obstacle to their genetic improvement. Gathering information on reproductive biology contributes significantly to the interest of breeders to have adequate tools for initiating the improvement program through crosses among high performing genotypes. To contribute to this, we examined the flowering phenology, pollen biology, stigma receptiveness at bud dehiscence and anthesis phases, and the in-vitro germination of the pollens in horsegram (Macrotyloma uniflorum). Pollens of horsegram were found to be either tricolporate or triporate, echinates in all accessions except in the collections from Benin. Ovaries in horsegram showed great variation in the number of ovules and activities of peroxidase indicated the receptiveness of stigma at bud dehiscence phase and during anthesis. A high number of ovules per ovary was found in accessions from Australia (Leichardt 1 and 2), Mali (LeichardtMali) and India (CPI22679). Pollen viability analysis implies the possibility of better results when pollinating during the day and immediately after the flower opens. The study provides information on the reproductive biology of horsegram for future hybridization program in order to enhance the performance of the crop and increase production. It also reveals differences in accessions from Benin compared with all other accessions from Mali, India or Australia. [ABSTRACT FROM AUTHOR]

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]

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]

Raspberry bushy dwarf virus (RBDV) is one of the major pollen-borne pathogens of the genus Rubus that causes drastic reduction of yield and degradation of berry quality. The aim of the study was to evaluate the quality of raspberry pollen and the effect of RBDV on pollination process. The research was carried out at the Institute of Horticulture. Within two years, 2017 and 2018, the pollen viability and pollen germination capacity of nine raspberry cultivars were analysed. The cross-pollination was done and the pollination quality of 31 crossing combinations was evaluated. The study found that although the pollen viability of cultivars infected with RBDV was higher than that of uninfected cultivars, there were no statistically significant differences. The viral contamination of the mother plant played a more important role in the pollination process. Pollination was better on uninfected mother plants and pollen germinated was faster than on infected plants. However, when the virus-infected cultivars were pollinated with infected pollen, the virus had an effect on the growth rate of pollen tubes, that decreased and the pollen tubes did not reach the ovary. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate flowering, pollen, and fruit set characteristics of locally registered pomegranate cultivars between two consecutive years. 'Dr. Ercan 35', 'Efenar 35', 'Kamilbey 35', and 'Tezeren 35' cultivars have been developed by cross-breeding programs. Open-, cross-, and self-pollination studies were performed with these cultivars using three trees in each replicate in the field. Number of anthers per flower, number of pollen grains per anther, viability, and germination tests were conducted in the laboratory. Fruit set ratio of self-pollinated combinations were lower than open-pollination. The fruit set ratio from self-pollination was obtained from 'Dr. Ercan' (60.3%), 'Efenar 35' (62.4%), 'Kamilbey 35' (50.5%), and 'Tezeren 35' (25.2%). The highest fruit set ratio (49.7%) was obtained from 'Kamilbey 35' × 'Dr. Ercan 35' combination. The highest number of characteristics was as follows: 'Tezeren 35' (402 anthers/hermaphrodite flowers), 'Kamilbey 35' (8550 pollen/anther, male flowers in the beginning of flowering), 'Efenar 35' (84.7% pollen viability, hermaphrodite flowers), 'Kamilbey 35' (71.2%, pollen germination, hermaphrodite flowers). In conclusion, at least one, two or more, pollinator cultivars are necessary for commercial plantations using with these recently released pomegranate cultivars. [ABSTRACT FROM AUTHOR]

Pollen viability affects the probability that a pollen grain deposited on a plant's stigma will produce a viable seed. Because a mature seed is needed before a gene flow event can occur, pollen viability will influence the risk of escape for genetically engineered (GE) crops.Pollen viability was measured at intervals for up to 2 h following removal of the pollen from the anthers. It was quantified at three temperatures and for different alfalfa varieties, including both conventional and Roundup Ready (RR) varieties. Pollen viability was assessed using in vitro germination.Time since removal from the anthers was the most prevalent factor affecting pollen viability in alfalfa. Pollen viability declined with increasing time at all three temperatures and for all varieties tested. Pollen viability was not affected by temperatures ranging between 25 and 37 °C and did not vary among plant varieties, including conventional and RR varieties.Bee foraging behaviour suggested pollen viability within the first 10 min following pollen removal from a flower to most affect seed production. Pollen longevity was predicted to have little impact on seed set and gene flow. Linking pollinator behaviour to pollen viability improved our understanding of its impact on gene flow risk. [ABSTRACT FROM AUTHOR]

The study evaluated the microsporogenesis of olive trees subjected to different agricultural pesticide applications during flowering. Inflorescences of cultivars Arbequina and MGS GRAP541 were subjected to agricultural pesticides: mineral oil, neem oil, dimethoate and deltamethrin. The floral buds were fixed in Carnoy for the microsporogenesis analysis and in Karnovsky for scanning electron microscopy. The slides were prepared by squash technique and staining with propionic carmine. The pollen viability was determined by Alexander's stain and in vitro germination. Results show that the quantification of abnormalities in meiosis in the two cultivars caused significant effect among the treatments, being that all differed statistically from the control group. Both methods showed a higher percentage of viable pollens in the control treatment and lower percentage of viability with the agricultural pesticides. The method of pollen viability by staining presented the highest averages of viable pollens, but when compared together, both methods presented a strongly related positive linear correlation. It was concluded that the used chemical products increased the percentage of chromosomal abnormalities during microsporogenesis, which interfered in the pollen viability of the two analyzed cultivars. The product deltamethrin caused the strongest effect on meiosis and on pollen viability. [ABSTRACT FROM AUTHOR]

The reproductive strategies and resources available in the flower are characteristics that stimulate research studies on the genetic improvement and fruit yield of commercial cultivars. In this sense, this study aimed to study the floral biology aspects of passion fruit cultivars in Tangará da Serra region, Mato Grosso State, Brazil at different evaluation times. The experiment was carried out with eight cultivars of yellow passion fruit from an ex situ germplasm bank of the State University of Mato Grosso. The floral resources (pollen and nectar) were evaluated in a completely randomized, factorial arrangement (8 cultivars x 5 evaluation times), with five replications. Throughout anthesis, the pollen viability, stigma receptivity, and sugar volume and concentration in the nectar were evaluated. The evaluations were carried out in 1-h intervals, between 1:30 and 5:30 p.m. The highest nectar volume production was at 2:30 p.m., decreasing gradually thereafter at the later evaluation times, for all cultivars. Pollen viability increased from the first to the second evaluation time and then decreased gradually until the last evaluation. Stigma receptivity was higher than 90% in all cultivars, at all evaluation times. BRS Rubi do Cerrado and FB 200 were the most promising cultivars for nectar volume and concentration, pollen viability, and stigma receptivity characteristics. [ABSTRACT FROM AUTHOR]

Asian pears have become increasingly popular in the European market, but their cultivation history in Europe is rather short. Pear is a demanding species in terms of pollen - donor cultivar. The self-fertility phenomenon in Asian pear cultivars is not currently known. The study was conducted in a 6-year pear orchard (of 23 Asian and 5 European cultivars) at the Mendel University in Lednice (Czech Republic). The following traits were assessed: number of pollen grains, pollen viability, pollen grain germination, self-fertility and the pollen germination index (PGI). European cultivar - 'Clapp's Favourite' and Asian cultivars - 'Zao Su Li', and 'Shinko' were characterized by the highest number of pollen grains (over 50,000 grains). Asian cultivar 'Dangshansu Li' had the lowest number of pollen grains (less than 10,000 grains). The pollen viability of Asian pears ranged between 90 and 100%. Among European pears, 'Williams Bon Chrétien' and 'Clapp's Favourite' exhibited the highest pollen viability (90%), while the lowest viability was observed for the pollen of cultivars 'Beurré Bosc' and 'Alexander Lucas' pear (60-70%). Additionally, it was found that the germination capacity of the latter two cultivars was very weak (40-70%). After open- pollination all investigated cultivars exhibited greater pollen germination index (PGI) comparing to selfpollination. After the cross-pollination the percentage of pollen tubes below the 20% value at half the length of the pistil suggested a strong incompatibility between the crossed cultivars. The results clearly showed that none of the Asian cultivars are self-fertile, and they require a pollen - donor to produce fruits. [ABSTRACT FROM AUTHOR]

[Objective] The aim of this study was to understand the flowering biological characteristics of different varieties Prunus domestica L. in Aksu Jiamu Experiment Station. [Method] Three varieties of plum as Prunus domestica L. cv.'French', Prunus domestica L. cv. 'Victoria' and Prunus domestica L. cv. 'Stanley' were the research subjects. The phenophases of blooming, and the morphological and developmental characteristics of floral organs were observed. The amount and viability of pollen and the stigma receptivity were measured. [Result] Three varieties of plum all blossomed in early April, and the florescence had lasted for 9-10 d. The average number of anthers was 28.48%. The average number of pollen grains in each flower was 28 700.0. The pollen germination rate was 27.4%.86.75% of the flowers were medium-styled or long-styled. There was no significant difference in the petal shape, color, anther number, calyx color, and flower ovary among the three varieties of plum. The stigma receptivity was strongest on the first day of flowering, and then dropped gradually. Therefore, the flowers of plum were manual pollinated on the first day of flowering. The duration time of stigma receptivity of Prunus domestica L. cv. 'Victoria ' was longer than the other cultivars, the duration time of stigma receptivity was about 5 d. [Conclusion] The pollen number and pollen germination rate of Prunus domestica L. cv. 'Stanley' were higher than the other cultivars, which be considered the most suitable pollinizer for plum. In contrast, the complete flower rate of Prunus domestica L. cv. 'French' and Prunus domestica L. cv. 'Victoria' was relatively high, but the pollen number and pollen germination rate of Prunus domestica L. cv. 'French' and Prunus domestica L. cv.'Victoria' were lower than Prunus domestica L. cv. 'Stanley', which are not suitable to use as a pollinizer for plum. [ABSTRACT FROM AUTHOR]

• The study describes a method for creating novel germplasm combining the rich flower color of tropical water lilies with the cold resistance of hardy cultivars. • The use of stigmatic secretion culture is an efficient method to measure the pollen viability of water lilies. • The optimal time for pollination was in the cup phase with extension for one-day of the flat period, shown by optimal stigma morphology, stigma receptivity, and stigmatic secretion. • Serious pre-fertilization barriers were found in the crosses between hardy and tropical water lilies, and overcoming the pre-fertilization barrier is an important way to improve the cross efficiency of these water lily cultivars. An improved germplasm combining the advantageous traits of tropical and hardy water lilies was assembled by cross-breeding. The pollen viability, stigma receptivity, and pollen tube behavior were assessed to avoid potential developmental problems resulting from cross-breeding. This is the investigation using the measurement of water lily pollen viability by culturing stigmatic secretions in vitro. Germination rates measured by this method were consistent with those found using 2,3,5 triphenyl-tetrazolium chloride staining. Pollen growth in vitro was the same on both the stigma and the style. Stigma morphology, stigma receptivity, and stigmatic secretions showed that the optimal time for pollination was in the cup phase with extension for one-day of the flat period. Three crosses in tropical water lilies all resulted in seeds (73.33%, 86.67%, and 100%) with the pollen tube growing normally in the style. Two out of three hardy water lily crosses produced seeds (16.67% and 65.38%); the third cross produced no seeds and little pollen germination, and it was found that the pollen tube was bent and the pollen was not able to enter the ovule smoothly. There were serious pre-fertilization barriers in the crosses between hardy and tropical water lilies, including low pollen germination, abnormal growth of the pollen tube in the style, showing bending at the apex or expansion in the middle, or the production of a callose, preventing the pollen tube from entering the ovule effectively. Overcoming the pre-fertilization barrier is an important way to improve the cross efficiency of tropical and hardy water lilies. [ABSTRACT FROM AUTHOR]

Ten self-fertile commercial sunflowers cultivars were evaluated for seed set with anti without exposure to bees. In the first planting, the number of foraging honey bees was smaller than in the second, and seed set for most cultivars did not differ between those bagged to exclude bees and ones that were open pollinated. In the second planting, however, a majority of cultivars had significantly greater seed set when capitula were exposed to bees compared with when they were not. The weight of seeds from open-pollinated capitula was greater than from those where bees were excluded. Environmental conditions also played a role in seed set as evidenced by differences between plantings in set on bagged capitula. In the first planting, average maximum and minimum temperatures were significantly higher than in the second, and overall seed set was significantly lower in capitula where bees were excluded compared with the second planting, Under the high temperature conditions, however, some cultivars set four times more seed on open-pollinated capitula compared with those that were bagged. These results suggest that foraging activity and cross-pollination by bees might mitigate reductions in seed set caused by high temperatures. [ABSTRACT FROM AUTHOR]