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Cytoplasmic male-sterility (CMS) is the primary source for the production of commercially viable onion F1 hybrids. The molecular interplay of the cytoplasmic-nuclear genes propels the restoration of fertility in the CMS system, making it cost-effective and stable. The use of the molecular markers that can determine the cytoplasm type and nuclear genotype reduces the amount of time and labour required. This study characterized the morphology of male sterile and fertile plants based on anther colour and pollen viability. Additionally, the molecular characterization of the organellar DNA differentiating cytoplasm and nuclear genotypes in 35 commercially grown open-pollinated varieties of Indian short-day onion was attempted. Our results revealed that morphological and microscopic observations for the identification of male sterile and fertile plants were not 100% corroborative. Markers located in the chloroplast (accD) and mitochondrial DNA (MKFR) revealed that Indian cultivars exhibited a greater frequency of N (normal) cytoplasm, lower frequency of S (sterile) cytoplasm and no occurrence of T (sterile) cytoplasm. All three markers viz., AcPMS1, AcSKP1, and jnurf13 revealed that 93 to 99% of the plants of all the varieties had homozygous recessive (msms) alleles at the Ms locus. The OPT marker classified the plants as having 38% msms, 39% Msms and 21% MsMs genotypes and needs further investigation. This underscores the pressing need for additional markers to precisely discern the Ms locus, facilitating the identification of male sterile and maintainer plants within open-pollinated populations of Indian short-day onions. Notably, male sterile cytoplasm was identified in eight commercial varieties, marking a pioneering revelation in Indian onion cultivation. [ABSTRACT FROM AUTHOR]

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

• 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]

Androgenesis is reported in a few tree crops such as citrus and papaya; however, there is little information available about guava. Different modified Chu (N6) media and cold pretreatments of floral buds were tested to induce embryogenic calli in the anthers of two white flesh guava cultivars, 'Round' and 'Pyriform'. Four modified Chu (N6) media formulations, i.e., M1 (400 mgL-1 casein hydrolysate, 200 mgL-1 glutamine, 0.2 mgL-1NAA, 1.0 mgL-1 KIN, 0.5 mgL-1 6-BAP, 0.5 mgL-1 zeatin and 5% coconut water), M2 (400 mgL-1 casein hydrolysate, 200 mgL-1 glutamine, 0.2 mgL-1NAA, 1.0 mgL-1 KIN, 0.5 mgL-1 6-BAP), M10 (0.5 mgL-1 2,4-D), and M11 (0.5 mgL-1 2,4-D and 50 mgL-1 PVP) enhanced anther swelling and callus formation. Genotypic variability was found in pollen viability, phenolic exudation, and anther tissue browning after cold pretreatment for 0-72 hrs. intervals. Anthers of 'Round' showed more pollen viability across cold pretreatment intervals with less phenolic exudations and tissue browning than 'Pyriform'. On both M10 and M11 media, anthers with uni-nucleate microspores developed embryogenic calli; however, anthers of 'Pyriform' resulted in more calli induction (69.58%) on M10 media, whereas anthers of 'Round' developed more calli (66.60%) on M11 media. The proliferating calli in white flesh 'Round' and 'Pyriform' cultivars and pink flesh 'Round' cultivar formed more embryogenic masses upon transfer to growth hormone-free Chu (N6) media under light conditions; however, embryos showed delayed maturity with limited germination. More genotypes shall be explored to enhance embryo germination, and embryogenic media shall be further fine-tuned. This study provides the foundation for the generation of homozygous lines in guava using androgenesis. [ABSTRACT FROM AUTHOR]

Background: The research was conducted to screen rice cultivars with resistance ability to high-temperature conditions and analyze the relationship between pollen viability and filled grain of native Indonesia rice cultivars. Methods: The rice seeds were germinated, sown into a tray and then transplanted into pots filled with sandy loam and compost 3:1. After 20% of flowering, four pots of each cultivar were kept under ambient temperature (28-32°C) and the other four pots were transferred to high-temperature (33-38°C) conditions. Pollen stainability and pollen germination were conducted using IKI solution and by germinating them under in vitro conditions respectively before being viewed under the light microscope. Yield characters were analyzed to obtain a relationship with pollen viability. Result: Percentage of pollen germination, filled and empty grains of rice cultivars significantly differed between the two conditions by t-test. Ciherang and Sigeudop were two resistant cultivars for high-temperature treatment, with filled grain percentage more than 85%. There was a strong relationship between pollen germination and filled grains at ambient temperature (r=0.95; p<0.01) and high temperature (r=0.94; p<0.01). Rice cultivars that show high pollen germination under high-temperature conditions would produce a high percentage of filled grains. [ABSTRACT FROM AUTHOR]

Pollen grains, the male gametophytes for reproduction in higher plants, are vulnerable to various stresses that lead to loss of viability and eventually crop yield. A conventional method for assessing pollen viability is manual counting after staining, which is laborious and hinders high-throughput screening. We developed an automatic detection tool (PollenDetect) to distinguish viable and nonviable pollen based on the YOLOv5 neural network, which is adjusted to adapt to the small target detection task. Compared with manual work, PollenDetect significantly reduced detection time (from approximately 3 min to 1 s for each image). Meanwhile, PollenDetect can maintain high detection accuracy. When PollenDetect was tested on cotton pollen viability, 99% accuracy was achieved. Furthermore, the results obtained using PollenDetect show that high temperature weakened cotton pollen viability, which is highly similar to the pollen viability results obtained using 2,3,5-triphenyltetrazolium formazan quantification. PollenDetect is an open-source software that can be further trained to count different types of pollen for research purposes. Thus, PollenDetect is a rapid and accurate system for recognizing pollen viability status, and is important for screening stress-resistant crop varieties for the identification of pollen viability and stress resistance genes during genetic breeding research. [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]

The purpose of this study was to select the suitable broad-spectrum stain for the determination of walnut pollen viability, determine the pollen viability of walnut, screen the suitable storage temperature for maintaining walnut pollen viability, and study the pollen morphology, which can provide a basis for walnut cross breeding and variety identification. In this study, six walnut cultivars mainly grown in Shaanxi were used as materials, the staining effect of TTC, MTT and I2-IK stains on walnut pollen was studied by single factor experimental design with medium method as control, the changes of walnut pollen viability were compared at room temperature of 20 °C, 4 °C and -20 °C, and the pollen morphological differences of 6 walnut cultivars were studied by scanning electron microscopy. The results showed that active and inactive pollen could be identified by MTT but TTC and I2-IK could not. The pollen variability determined by MTT and medium method was consistent among 6 walnut cultivars. The initial pollen viability of 6 walnut cultivars was divergent greatly, and the pollen viability of ‘Zhonglin 5’ and ‘Xiangling’ was significantly higher than that of other 4 cultivars. The pollen viability of walnut could only be maintained for 4-5 days at room temperature of 20 °C with 20% water content. The pollen life can be effectively prolonged for 5- 9 days at 4°C, and the pollen viability of most cultivars can only be maintained for 2 days at -20 °C . The pollen grains of 6 walnuts were nearly spherical, and the size of pollen grains was significantly differences among cultivars, in which the polar axis ranged from 39. 15 μm to 44. 35 μm, and the equatorial axis ranged from 33. 58 μm to 42. 86 μm. The pollen grains of ‘Qingxiang’ and ‘Shaanhe’ were relatively large. The pollen grains of walnuts had 13 to 20 round or oval germ pores with the long axis ranging from 3. 26 μm to 3. 75 μm, and the short axis ranging from 2. 75 μm to 3. 35 μm. The germ pores number differed significantly among cultivars. This study estimated that the stain MTT had low selectivity and broad spectrum in pollen staining of walnut cultivars, which can be used as the preferred dye for walnut pollen viability determination. The pollen life of 6 cultivars was short in natural circumstance, the initial pollen viability was relatively low ( less than 40%) besides there was great diversity among cultivars. The storage at 4 °C was favorable for walnut pollen storage whereas -20 °C was unfavorable. There were significant differences in pollen grain size and germ pore number among 6 walnut cultivars. [ABSTRACT FROM AUTHOR]

• Hemerocallis are plants found all over the world. • Pollen viability allows success in breeding programs. • The suitable culture medium allows greater germination percentage of the pollen grain. • There is diversity in pollen germination among Hemerocallis genotypes. • The maximum percentage of pollen germination depends on the time after incubation. Hemerocallis is a floriferous species, which presents numerous genotypes that are constantly crossed, generating new cultivars. The germination and viability of pollen are influenced both by factors that are intrinsic and extrinsic to the pollen. In view of the above, the purpose of this study was to establish a growth medium for the germination of pollen grains. Cultivar Morgana was used in the experiments performed to establish the growth medium, in which four pH ranges were tested alongside four agar concentrations. For the next test, five sucrose concentrations were tested. Afterwards, four boric acid concentrations were added to the medium, finally followed by four calcium nitrate concentrations. After the definition of the growth medium, the incubation time for pollen grains germination of the species was evaluated. The results were then applied to four cultivars in order to verify the respective germination percentages. It was noted that the highest percentage of in vitro germination occurred with the concentrations of 4 g L−1 agar, 74.6 g L−1 sucrose, 800 mg L−1 boric acid and 590 mg L−1 calcium nitrate, with a pH of 5.74 and ideal incubation time of 3 h. Regina being to cultivar with the highest germination percentage. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is one of the major cereal crops worldwide with wheat and maize. A total of two field experiments were performed to evaluate the response of some rice cultivars to various foliar zinc (Zn) concentrations based on different measurements, such as agronomic, yield, yield compounds, and grain technological parameters. The experimental layout was a split plot in three replicates; the five rice cultivars (Skaha 101, Giza178, Yasmeen, Fourate, and Amber 33) were distributed in the main plots while the four foliar applications of Zn (1,500, 2,000, 2,500 mg/L besides spray water) were occupied the sub-plots. The findings showed significant differences among the five rice cultivars regarding plant height, grain yield, straw yield, biological yield, harvest index, 1,000-grain weight, panicle length, protein percentage, and grain Zn content. There is a significant effect of Zn on all plant attributes. A significant interaction between rice cultivars and foliar application of Zn was observed, whereas fertilizing Giza 178 with foliar application of Zn at the rate of 2,500 mg/L achieved the highest mean values of grain yield and straw yield, biological yield, harvest index, 1,000-grain weight, panicle length, protein %, and Zn content followed by Sakha 101 with Zn application at the rate of 2,000 mg/L, respectively, in both seasons. The rice cultivars significantly differed in hulling (%), broken (%), hardness, grain length, shape, amylose (%), gel consistency, and gelatinization temperature. Unfortunately, the commercial Zn product used was genotoxic to pollen grains with a higher rate of Zn. Aberrations were observed such as stickiness, ultrastructural changes in the exterior and interior walls, partially or fully degenerated grains, and shrunken and unfilled grains. This study concluded that using Zn application at the rate of 2,000 mg/L to protect human and environmental health, the side effects and toxicity of the local commercial Zn product market should be investigated before making recommendations to farmers. [ABSTRACT FROM AUTHOR]

Temperature rise in March induces forced maturity in wheat (Triticum aestivum L.), which generally reduces the grain-filling period under North Indian conditions. A field experiment was conducted at the Punjab Agricultural University, Ludhiana, India, during 2015–16 and 2016–17 to evaluate the effect of salicylic acid on plant growth, physiological parameters, and grain yield of two wheat cultivars sown at different dates. A split-split-plot design was used, with sowing dates (November 5, November 20, and December 5) as main plots, wheat cultivars (WH1105, PBW677) as sub-plots, and salicylic acid foliar treatments (control, water spray, salicylic acid 75 and 100 mg l−1) as sub-sub plots. The highest tiller count, atLEAF-chlorophyll index, pollen viability, number of grains ear−1, 1000-grain weight, biological and grain yield were recorded for the November 5 sowing date. Salicylic acid foliar application at 75 and 100 mg l−1 increased the grain-filling period, improved the normalized difference vegetative index (NDVI), pollen viability, number of grains ear−1, proline content, 1000-grain weight, and grain yield. We concluded that wheat cultivars WH1105 and PBW677 can be grown successfully by sowing early (November 5) and that foliar application of salicylic acid at 75 mg l−1 can improve the wheat grain yield under north Indian conditions. [ABSTRACT FROM AUTHOR]

High temperatures and increasing CO2 concentrations are a major threat to global wheat (Triticum aestivum L.) production, demanding the development of heat‐tolerant wheat cultivars. Plant physiological traits are potential surrogates for evaluating genetic variation for crop stress tolerance. This research evaluated 23 Australian wheat cultivars and two breeding lines for heat‐tolerance by characterising the associated physiological traits. The interactive effects of heat‐stress and elevated CO2 were studied under controlled greenhouse conditions and delayed sowing in the field with exposure to higher temperature. Physiological changes, pollen viability and grain yield were assessed. A significant correlation was observed between physiological and agronomical traits under high temperature at 35°C and elevated CO2 at 800 µl L−1, providing evidence of adaptation to high temperatures in some genotypes. Variation in stomatal conductance, transpiration rate, canopy temperature, leaf chlorophyll and photosynthesis were associated with maintenance of pollen viability and grain yield at high temperatures. Of the genotypes assessed, seven were classified as heat tolerant at both ambient and elevated CO2 and nine were heat susceptible while the remainder showed a variable response to CO2 at high temperatures. Field data confirmed the heat responses of the most heat‐tolerant and susceptible genotypes. The heat tolerant genotypes identified are candidates for further breeding and selection to improve adaptation to a changing climate. [ABSTRACT FROM AUTHOR]

High temperatures and increasing CO2 concentrations are a major threat to global wheat (Triticum aestivum L.) production, demanding the development of heat‐tolerant wheat cultivars. Plant physiological traits are potential surrogates for evaluating genetic variation for crop stress tolerance. This research evaluated 23 Australian wheat cultivars and two breeding lines for heat‐tolerance by characterising the associated physiological traits. The interactive effects of heat‐stress and elevated CO2 were studied under controlled greenhouse conditions and delayed sowing in the field with exposure to higher temperature. Physiological changes, pollen viability and grain yield were assessed. A significant correlation was observed between physiological and agronomical traits under high temperature at 35°C and elevated CO2 at 800 µl L−1, providing evidence of adaptation to high temperatures in some genotypes. Variation in stomatal conductance, transpiration rate, canopy temperature, leaf chlorophyll and photosynthesis were associated with maintenance of pollen viability and grain yield at high temperatures. Of the genotypes assessed, seven were classified as heat tolerant at both ambient and elevated CO2 and nine were heat susceptible while the remainder showed a variable response to CO2 at high temperatures. Field data confirmed the heat responses of the most heat‐tolerant and susceptible genotypes. The heat tolerant genotypes identified are candidates for further breeding and selection to improve adaptation to a changing climate. [ABSTRACT FROM AUTHOR]

Climate change is causing temperature increment in crop production areas worldwide, generating conditions of heat stress that negatively affect crop productivity. Tomato (Solanum lycopersicum), a major vegetable crop, is highly susceptible to conditions of heat stress. When tomato plants are exposed to ambient day/night temperatures that exceed 32 °C/20 °C, respectively, during the reproductive phase, fruit set and fruit weight are reduced, leading to a significant decrease in yield. Processing tomato cultivars are cultivated in open fields, where environmental conditions are not controlled; therefore, plants are exposed to multiple abiotic stresses, including heat stress. Nonetheless, information on stress response in processing tomatoes is very limited. Understanding the physiological response of modern processing tomato cultivars to heat stress may facilitate the development of thermotolerant cultivars. Here, we compared two tomato processing cultivars, H4107 and H9780, that we found to be constantly differing in yield performance. Using field and temperature-controlled greenhouse experiments, we show that the observed difference in yield is attributed to the occurrence of heat stress conditions. In addition, fruit set and seed production were significantly higher in the thermotolerant cultivar H4107, compared with H9780. Despite the general acceptance of pollen viability as a measure of thermotolerance, there was no difference in the percentage of viable pollen between H4107 and H9780 under either of the conditions tested. In addition to observations of similar pollen germination and bud abscission rates, our results suggest that processing tomato cultivars may present a particular case, in which pollen performance is not determining reproductive thermotolerance. Our results also demonstrate the value of combining controlled and uncontrolled experimental settings, in order to validate and identify heat stress-related responses, thus facilitating the development of thermotolerant processing tomato cultivars. [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]

Hippeastrum sp. is a popular cut flower and a popular potted plant, currently occupying the 11th position among cut flowers sold on the Dutch flower auctions. Hippeastrum × chmielii was bred by Henryk Chmiel at the Warsaw University of Life Sciences (WULS), Poland. The aim of this study was designed to test the ability of two clones of H. × chmielii to reproduce generatively by pollinating by three cultivars of Hippeastrum hybridum – 'Gervase', 'Rio Negro' and 'Royal Velvet'. Pollen viability was tested by germination on the medium and by acetocarmine staining. The receptiveness of the stigmas and ovules of H. × chmielii and thus their ability to possibly accept compatible pollen were checked by staining with red alizarin. The viability of pollen grains of tested cultivars was estimated at 66.4–83.0% and their high ability to develop pollen tube was found. It was determined that the embryos of both H. × chmielii clones were fully receptive. A total of 72 crossings were performed in 6 combinations. Seeds collected about 1 month after pollination were germinated immediately after harvest either on moist tissue paper on Petri dishes or in jars with distilled water. After 28 days the percentage of germinated seeds ranged between 48.3% and 77.9%, for different crosses. In the case of seeds obtained from crossing H. × chmielii clone 18 × H. hybridum 'Gervase' a higher average percentage of germinated seeds was obtained in jars while no differences were noted between the germination methods in other cases. [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 study was conducted to examine the effect of storage temperature and duration on the viability and in vitro germination of pollen grains of seven pistachio cultivars. Pollens were stored at room temperature (24±2 oC), refrigerator (4 oC) and freezer (-5 oC) for 0, 1, 2, 3 and 4 weeks. Pollen viability was estimated by using staining methods including tetrazolium test (TTC), iodine and potassium iodine (IKI) and safranin solutions, and using an in vitro pollen germination. The results showed that at all storage methods and durations, pollen viability and in vitro pollen germination were significantly the highest for Batouri and Ashouri cultivars and the lowest for Marawhi and Elemi cultivars. The highest pollen viability as estimated by safranin staining was attained when pollens were stored under freezer condition. However, pollen viability by TTC was the lowest at room temperature storage. In addition, in vitro pollen germination and viability significantly decreased as storage duration increased. This study revealed no differences between in vitro germination percentages in refrigerated and freezer stored pollen up to 2 weeks. Meanwhile, in vitro germination of room-stored pollen gradually decreased when storage duration increased. At the end of storage period, pollen viability was reduced slightly under freezer conditions, whereas, the reduction in viability was the highest for refrigerated and room-stored pollen with no differences between them. This study showed a significant interaction effect of cultivar x storage temperature x storage duration on pollen viability but not for in vitro pollen germination. [ABSTRACT FROM AUTHOR]

The interspecific hybridization was performed between five tulip cultivars, including 'Judith Leyster,' 'World's Favorite,' 'Heart of Poland,' 'Crispa Fabio' and 'Jumbo Pink,' and five wild species, including Tulipa thianschanica Regel, T. sinkiangensis Z. M. Mao, T. altaica Pall. ex Spreng, T. buhseana Boiss. and T. schrenkii Regel., to explore the cross-compatibility between tulip cultivars and wild species. In this experiment, pollen size and germinability, pollen storage life, stigma receptivity, fruit-setting, hybrid seed germination and bulblet formation were observed. The chromosome count and karyotype of hybrids were also examined. The results showed that T. altaica and five cultivars had closer genetic relationship than the other four wild species. Among the five wild Tulipa species T. altaica has the largest pollen and the highest germination rate (65.23%) compared with any other four species. The pollen viability of all five pollen parents decreased slowly across all stages at − 20 °C and decreased rapidly at 25 °C and 4 °C. A total of 1066 hybrids were obtained from interspecific hybridization combinations, including 'Heart of Poland' × T. thianschanica, 'Heart of Poland' × T. altaica, 'Crispa Fabio' × T. altaica, 'Jumbo Pink' × T. altaica, 'Crispa Fabio' × T. schrenkii and 'Jumbo Pink' × T. schrenkii. According to the chromosome count, approximately 20% and 12% aneuploidy hybrids were produced from 'Heart of Poland' (2n = 3x = 36) × T. thianschanica (2n = 2x = 24) and 'Heart of Poland' (2n = 3x = 36) × T. altaica (2n = 2x = 24), respectively, and the any other hybrids were diploid (2n = 24) in these two crosses. All the hybrids from crosses of diploid parents were diploid (2n = 24). Meanwhile, the karyotype characteristics of six parents and their six progenies were also elaborated, which had similar 3A and 3B karyotypes. The results of this study may facilitate tulip interspecific hybridization in the future. [ABSTRACT FROM AUTHOR]

The determination of viability and the preservation of pollen grains are useful tools for breeding of ornamentals, especially when the synchronization of flowering between species or cultivars does not occur naturally. Thus, the objective of this study was to characterize the flowering and to evaluate the preservation and maintenance of the viability of pollen grains in cultivars of amaryllis (Hippeastrum sp.) subjected to three storage temperatures. Anthers of five cultivars of amaryllis were collected from 12 to 24 hours after anthesis. One part of the anthers was immediately used for germination tests using in vitro germination in culture medium and the other part was stored at temperatures of 25, 8 and -20 °C. Pollen grains were germinated in culture medium at 0, 20, 75, 125, 165, 205 and 245 days after storage. All cultivars of amaryllis showed an accelerated loss of viability at 25 °C storage temperature. The 'Bull' cultivar showed higher recalcitrance to cold-storage, while 'Intokazie' and 'Pink Panther' cultivars showed higher longevity and higher percentage of germination along storage. The temperature of -20 °C resulted in the best responses for the maintenance of the integrity and preservation of the viability of pollen grains of different cultivars of amaryllis. [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]

This study was conducted on six pistachio cultivars (Lazaourdi, Nab-El Jamal, Boundiki, Batouri, Marawhi and Aschouri) to investigate the percentage of pollen viability and in vitro pollen germination under stored and non-stored (fresh) conditions. The results indicated that there was a significant interaction between pollen viability of pistachio cultivars and storage period. This study showed that the non-stored (fresh) pollen of cultivars Batouri and Lazaourdi had significantly the highest viability (87%) and in vitro pollen germination (69.7%), respectively; indicating that such cultivars could be used as best pollinators. On the other hand, cultivar Nab-El Jamal had the lowest viability (43.7%) and in vitro pollen germination (40.3%). It was found that pollen viability for all stored pollen cultivars were significantly reduced by 30% when compared with non-stored (fresh) pollen. However, stored pollen germination for one month was zero for all pistachio cultivars. In addition, the results of viability for all fresh pollen cultivars were poorly linearly correlated (r2=0.149) with the results of in vitro germination of fresh pollen. Further research is required to examine both pollen viability and in vitro pollen germination under different short and long-term storage periods and methods. [ABSTRACT FROM AUTHOR]

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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 objective of this study was to analyze the effects of low storage temperatures on the quality of pollen obtained from the sweet cherry cultivars 0900 Ziraat, Regina, Starks Gold, and Sweet Heart. The pollen was stored at 4 °C, -20 °C, and -80 °C for 12 months, and its viability and germinability were determined at 3-month intervals. The results demonstrated that the initial pollen viability varied between 73.62% and 79.37%, while pollen germinability varied between 41.24% and 53.56%. The percentage of pollen viability declined remarkably from the third to 12th month by almost 3% in 4 °C storage. The pollen viability for the other two storage temperatures (-20 °C and -80 °C) was greater than 50% by the end of the 12th month. It can be concluded that the pollen quality of these cultivars can be preserved sufficiently at temperatures less than -20 °C. [ABSTRACT FROM AUTHOR]

A study on floral biology of black pepper cultivars that cover anther dehiscence, pollen viability and stigma receptivity was carried out with the aim to improve the efficiency of intervarietal hybridisation in black pepper breeding work. In this study, 10 black pepper cultivars were used, namely 'Semongok Aman', 'Kuching', 'Semongok Emas', 'Semongok Perak', 'Semongok 1', 'Nyerigai', 'India', 'Lampung Daun Lebar', 'Sarikei' and 'Yong Petai'. The results show that anthesis in the 10 black pepper cultivars occurred between 10.25 pm and 10.50 pm. In the pollen viability study, results suggest that pollen are more viable between five and 10 hours after anther dehisced. However, there are variations among the cultivars for the optimum viable stage. For stigma receptivity, the results show that stigmas at Stage 2 (elongation and spreading of stigmata) and Stage 3 (complete emergence and wide spreading of stigmata) had better receptivity than Stage 1 (first appearance of stigmata). There was no difference in stigma receptivity stages among the 10 cultivars. This study thus, shows the most suitable time for intervarietal hybridisation via artificial pollination. [ABSTRACT FROM AUTHOR]

In the present study, 11 lentil (Lens culinaris Medik) genotypes including heat tolerant and heat sensitive genotypes identified after a screening of 334 accessions of lentil for traits imparting heat tolerance, were characterised based on physiological traits and molecular markers. Results showed a higher reduction in pollen viability among sensitive genotypes (up to 52.3%) compared with tolerant genotypes (up to 32.4%) at 43°C. Higher photosynthetic electron transport rate was observed among heat tolerant genotypes and two heat tolerant lentil genotypes, IG 4258 (0.43) and IG 3330 (0.38) were having highest Fv/Fm values. However, membrane stability was significantly higher in only one heat tolerant genotype, ILL 10712, indicating that different mechanisms are involved to control heat tolerance in lentil. The molecular characterisation of lentil genotypes with 70 polymorphic SSR and genic markers resulted into distinct clusters in accordance with their heat stress tolerance. A functional marker ISM11257 (intron spanning marker) amplifying an allele of 205 bp in size was present only among heat tolerant genotypes, and could be further used in a breeding program to identify heat tolerant lentil genotypes. The findings of this study will contribute to the development of heat tolerant lentil cultivars. [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]

The effect of selected sex steroids on plant morphology, flowering and sex expression in Cucumis sativus cultivar Kmicic F1 was investigated. Plants were cultured on the medium with the addition of progesterone, testosterone and estrone at concentrations of 0.1 and 1.0 μM. All tested steroids caused shortening in the main stem over the control, while the number of main stem nodes was similar to the control. Testosterone and progesterone stimulated female flower, decreasing male flower production. Plants cultured on the medium with estrone had shortest stems and the total number of flowers produced was more than four-fold lower compared to the control; however, a shift toward femaleness was observed. Application of the tested sex steroids in vitro altered flower morphology. Pollen viability in the anthers of male flowers developed on plants cultured on the media with steroids was decreased, compare to control, suggesting their effect on pollen development. [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]

• Anthesis and pollen functionality were compared in an apricot germplasm collection. • Early, intermediate, late-flowering cultivars showed high initial pollen viability. • Pollen germination was assessed within the effective pollination period. • Pollen germination was differently affected by 5 °C, 15 °C, and 25 °C treatments. • High temperature significantly decreased pollen germination in most cultivars. Prunus armeniaca L. is widely cultivated in the Mediterranean area including Southern Italy where local cultivars are recognized for their excellent quality. Gradual warming and abrupt variations of seasonal temperatures are expected to significantly impact the Mediterranean area with potential implications on many crops including apricot. In this scenario, the identification of physiological processes involved in heat-stress responses and the selection of genotypes resilient/tolerant to high temperatures and heat waves are necessary. The aim of this study was to investigate possible differences in flowering phenology and the effect of different temperatures on pollen functionality of 13 apricot cultivars traditionally cultivated in the Campania region (Southern Italy). According to phenological data collected in the field, the studied cultivars were grouped in early, intermediate, and late flowering cultivars. Single flower anthesis was on average 4.9 days in early and intermediate flowering cultivars, whereas late flowering cultivars showed a shorter duration (4.0 days). Pollen of flowers at balloon stage showed a uniformly high viability among all cultivars. To investigate on possible effects of temperature during the effective pollination period (EPP), pollen from the different cultivars was pre-incubated at 5 °C, 15 °C, and 25 °C for 48-h and germinability was then assessed after further 24 h in-vitro germination at the same temperature treatments. The first two temperature values correspond respectively to the minimum and maximum average temperatures of the local area; whereas 25 °C simulated the heat waves recently recorded in the farm during apricot flowering periods. As regard pollen germinability, 15 °C revealed to be the most suitable temperature for apricot pollen to germinate within the EPP. Conversely, 5 °C and 25 °C significantly reduced pollen germination in most cultivars and particularly in intermediate flowering cultivars. Noticeably, a few cultivars showed no difference in pollen germination under the different temperature treatments, preserving high pollen germinability (>70%) even at high temperatures. Overall, our findings highlighted that pollen germination is extremely sensitive to temperature with significant variations among apricot genotypes. Results confirmed that reproductive traits such as pollen germinability represent an important parameter to consider for monitoring fruit production, in the processes of cultivar selection for new orchard plantations and in breeding projects. Moreover, traditional apricot cultivars as those of the Campania region confirmed to be a precious source of genetic diversity possessing a significant pollen resilience to temperature changes. [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]

Reproductive barriers exist in some water lily crosses that result in low seed set and low breeding efficiency. We investigated pollen morphology, pollen viability, microspore development, pistil receptivity, and embryo and endosperm development in six water lily crosses using paraffin section as well as light and scanning electron microscopy (SEM) techniques. The results indicated that the percentage of pollen with normal morphology ranged from 8.9% to 55.2%. The pollen viabilities o f 'Fen Zhuang', 'Bai Lu', and 'Hong Ying' were 33.9%, 3.3%, and 20.7%, respectively. Stigmatic pollen germination peaked at 12 h after pollination and varied from 0.3 to 65.7 grains per stigma among the crosses. The production of embryos with normal morphology ranged from 0% to 43.6% at 5 days after pollination, from 0% to 31.4% at 15 days after pollination, and from 0% to 19.7% by 20 days after pollination. The seed sets of the six crosses were from 0% to 10.9%. Our results suggest that the low seed set in some crosses is the result of low pollen viability, low pistil receptivity, and embryo abortion. [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]

Highlights: [•] Piriformospora indica enhanced P content and growth of Cyclamen persicum at standard P supply. [•] Numbers of flowers and unfolded leaves increased, while cultivation period decreased. [•] The proportion of homogeneous microspores and viable pollen and ovules was elevated. [Copyright &y& Elsevier]

The aim of this study was to evaluate the viability and longevity of the pollen grains of the olive cultivar ‘Picual’, the most extensive and important olive cultivar in the Iberian Peninsula. Over a 3-year period (2007–2009), viability of the pollen grains of 15 ‘Picual’ cultivar trees was measured using the Fluorochromatic Reaction (FCR). These olive trees were distributed along different altitudinal areas of the province of Jaen (southeast Iberian Peninsula). The percentages of viability did not show any geographical variability. In general, the percentage of viability did not vary from one year to another. With an average value of 49%, the viability of the pollen in the cultivar ‘Picual’ could be classified as medium-range. ‘Picual’ pollen grains have the highest viability after 24 hours of anther dehiscence. Viability declines rapidly with time. The longevity of the pollen grains was about seven days. The first three days after anthesis are the most important for fertilisation. A rapid decline in pollen viability may considerably reduce effective fertilisation and could negatively influence fruit production. For this reason, these findings should be considered for the improvement of olive fruit yields. [ABSTRACT FROM PUBLISHER]

Abstract: An improved in vitro pollen germination method was developed for avocado (Persea americana Mill.). The effect of different concentrations of sucrose, polyethylene glycol (PEG), Mg and Ca on pollen germination was evaluated in order to determine the optimal pollen germination medium, i.e. that maximizing the percentage of pollen germination and minimizing the percentage of bursted pollen grains. Once the germination medium was optimized we used it to study the effect of temperature on in vitro pollen germination and tube growth in different cultivars from the three botanical varieties of avocado, that differ in their adaptation to environmental conditions. Significant differences in percentage of pollen germination and in pollen tube growth were observed among cultivars. These results could have implications not only for optimizing pollen management in avocado but also to select the best pollinizers for a particular cultivar. [Copyright &y& Elsevier]

The genetic diversity among H. macrophylla (Thunberg) Seringe taxa is limited as a result of the restricted native distribution and multiple breeding programs that used the same taxa and targeted similar breeding goals. This study assessed the compatibility of interspecific crosses between Hydrangea macrophylla and H. angustipetala Hayata as a source of genetic diversity. Two lacecap cultivars of H. macrophylla, 'Lady in Red' and Midnight Duchess® ('HYMMAD II'), were compatible with H. angustipetala. Hybridity of progeny was confirmed by simple sequence repeat markers and morphological comparisons. Some hybrids had red- or purple-pigmented stems, which are characteristic of 'Lady in Red' or Midnight Duchess®, respectively. All hybrids had white lacecap inflorescences. Some of the hybrid flowers were fragrant. Winter leaf retention of the hybrids ranged from deciduous to semievergreen. Male fertility of progeny was evaluated by. fluorescein diacetate staining of pollen. 'Lady in Red', Midnight Duchess®, and H. angustipetala had 62%, 58%, and 79% stainable pollen, respectively, whereas the 'Lady in Red' x H. angustipetala and Midnight Duchess® x H. angustipetala hybrids had means of 48% and 47% stainable pollen, respectively. Selected progeny were used to develop F2 and BC1 populations. The interspecific hybrids produced in this study were attractive, fertile plants that are being used in further breeding to develop new cultivars. [ABSTRACT FROM AUTHOR]

We investigated the responses of staminate and pistillate floral components of Prime-Jan and Prime-Jim primocane-fruiting blackberry (Rubus L. subgenus Rubus Watson) to three different growth chamber temperature regimens, 35.0/23.9 °C (HT), 29.4/18.3 °C (MT), and 23.9/12.8 °C (LT). Temperature was negatively related to flower size, and morphologically abnormal floral structures were evident in 41% and 98% of the MT- and HT-grown plants, respectively. Anthers of LT- and MT-grown plants dehisced. The viability of pollen (as deduced through staining) from Prime-Jan grown at LT or MT exceeded 70%, whereas that of Prime-Jim pollen was significantly reduced (<40%) by the MT regimen. In vitro pollen germinability (typically <50%) was negatively influenced by temperature but was unaffected by cultivar. Pollen useful life was diminished under HT conditions; LT-grown pollen held at 23.9 °C retained 63% of its original germinability over a 32-h period, while the germinability of that held at 35.0 °C for 16 hours decreased by 97%. Virtually all flowers cultured under HT conditions were male sterile, exhibiting structural or sporogenous class abnormalities including petaloidy and malformation of tapetal cells or microspores; HT anthers that were present, failed to dehisce. Stigma receptivity, pistil density, and drupelet set were also negatively influenced by increased temperature; values for these parameters of floral competency among control plants were reduced by 51%, 39%, and 76%, respectively, in flowers cultured under HT conditions. In this study, flowering and fruiting parameters, and presumably the yield potential of Prime-Jan and Prime-Jim, were adversely affected by increased temperature. However, their adaptive response to heat stress under field conditions awaits assessment. [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]

Four pepper cultivars were grown under winter low night temperature (LNT) conditions (night temperature of 10±2 °C and day temperature which did not exceed 24 °C) in a greenhouse in Bet Dagan, Israel. In all four cultivars, LNT conditions caused a decrease in the number of pollen grains and a reduction in their germinability, in comparison with pollen of control plants grown in another greenhouse under higher temperature conditions (night temperature of 20±2 °C and similar day temperatures). Analysis of carbohydrates content in the later stages of pollen development revealed that LNT caused a reduction in starch concentration 4 days before anthesis (A-4), and in the concentrations of sucrose and reducing sugars (glucose and fructose) at anthesis (A). It is suggested that low temperatures hinder pollen functioning in pepper, by interfering with starch accumulation at A-4, thereby decreasing the concentrations of soluble sugars in the mature pollen grains. The fruits of the LNT-grown plants, except for cv. Devilla, were smaller, seedless and misshapen. The reason for the ability of cv. Devilla to set seeds and normal fruits under LNT conditions need further investigation. [Copyright &y& Elsevier]

In vitro germination assays are frequently used in screening trials to evaluate the pollen viability of pollinizers. To be effective, screening trials must have defined threshold criteria, from which individuals can then be assessed. However, despite decades of research on pollen viability, no established threshold is available to categorize apple cultivars based on their in vitro pollen tube lengths. This study aimed to identify and characterize the subgroups of cultivars based on their pollen tube growth performance. In vitro pollen tube lengths of 41 individuals were determined by incubating samples on artificial germination media at 15 and 25 °C. A six-number summary statistic was calculated, and hierarchical clustering on principal component (HCPC) analysis was used to determine and characterize subgroups. Furthermore, a decision tree model was used to predict class membership for future datasets. HCPC analysis partitioned the 41 individuals into three subgroups with different performances. The decision tree quickly predicted the cluster membership based on the second quartile at 15 °C and the third quartile at 25 °C. The thresholds from the decision tree can be used to characterize new observations. The use of the methods will be demonstrated using a case study with 29 apple accessions. [ABSTRACT FROM AUTHOR]

• The studied cultivars had medium-sized and subspheroidal-shaped pollen grains. • The exine ornamentation was defined as reticulate with a heterobrochate reticulum. • L. 'Rosabeth' was sterile due to meiotic abnormalities associated with triploidy. • The studied cultivars had small genomes and basic chromosome numbers of x = 7. The genus Lachenalia J. Jacq. ex Js. Murray (Asparagaceae) comprises 136 species endemic to South Africa and Namibia. These bulbous geophytes are considered to have excellent horticultural potential due to their morphological and genetic diversity, and thus have been chosen for the initiation of a breeding program to develop new cultivars that suitable for commercial use. From breeding perspective, studies on pollen viability and morphology are of great importance, since pollen quality represents an essential factor that influences crossbreeding processes. Therefore, to comprehensively characterize the pollen of selected Lachenalia cultivars, we conducted a multi-level analysis in which we investigated the processes of microsporogenesis and pollen grain development, as well as evaluated pollen morphology and viability. We also performed somatic chromosome counts and flow cytometry, thereby providing, for the first time, valuable cytogenetic data on the chromosome numbers and nuclear DNA contents of these cultivars. Morphologically, all the pollen grains were classified as medium-sized, subspheroidal in shape, and monosulcate with a single elongated aperture. Their exine ornamentation was categorized as reticulate with a heterobrochate reticulum. The pollen viability analysis revealed one of the cultivars to be nearly completely sterile, however, we were able to explain this phenomenon and found that this cultivar was affected by meiotic abnormalities associated with its triploid nature. Based on the obtained results, three of the studied cultivars may be considered as suitable pollinizers. From the perspective of applied research, the findings of our research offer important information for selecting appropriate donors for cross-pollination in the development of new Lachenalia cultivars. [ABSTRACT FROM AUTHOR]

The breeding system consists of mulberry (Morus spp.) cultivars such as Mysore local and Sujanpur 1 (Females) and S34, S13, DD, RFS 135, Ber.S1, Ber.C776 and V1 (males) were examined. In the month of March, the maximum seed set percentage ranges from 65.54 to 74.81 was observed in cross combinations using V1, S13, RFS135 as male parents. Whereas in September, the maximum seed set ranges from 62.82 to 68.40 was observed in cross combinations using Ber.S1, S13 and DD as male parents. The environment or a particular period such as temperature, humidity influenced on the rate of seed set. Pollen fertility is maximum in S34, S13, and V1 (97.0, 95.50 and 95.0). March month is better for crossability than in the month of September. [ABSTRACT FROM AUTHOR]