Pollen Viability Rate Research Articles

Pollen Characteristics of Diploid and Tetraploid Grape Cultivars

For a successful grapevine breeding program, pollen viability, germination ability, and cultivar compatibility information are of vital importance. In this study, pollen viability, germination rates, pollen tube lengths, and pollen tube diameters of three grape cultivars [Kyoho (4n), Ekşi Kara (2n), and Gök Üzüm (2n)] were investigated. Pollen viability rates were determined using the IKI (iodine potassium iodide) staining test. In vitro, pollen germination rates were determined using a semi-solid medium containing 20% ​​sucrose and 1% agar. As a result, significant differences were detected in pollen viability, germination rates, and pollen tube lengths of the examined grape cultivars. The first germination started at the 48th hour in all three grape cultivars. In cv. Ekşi Kara had the highest pollen viability while the lowest (3.05%) value in terms of pollen germination was determined. Pollen tube length and pollen tube diameter of the cv. Kyoho had higher values ​​than the other two diploid cultivars. Pollen tube formation started in the first 48th hours, while pollen tube growth continued to increase until the 96th hours. As a result, it was confirmed that the flower structure of the cv. Ekşi Kara was functionally female. In suitable ecologies, diploid cv. Gök Üzüm and tetraploid cv. Kyoho were found to be usable as pollinators.

Effects of Putrescine and Spermine on Pollen Germination Levels of Some Olive Cultivars

In this study, it is aimed to determine the effects of putrescine and spermine on pollen germination levels of 8 olive cultivars. Arbequina, Gemlik, Halhalı, Karamani, Kozan yerli, Saurani, Sayfi and Şami olive cultivars were used as material. In the study, 5 spermine doses (0,25mM, 0,125 mM, 0,025 mM, 0,05 mM and 0,005 mM) and 5 putrescine doses (0,20 mM, 0,10 mM, 0,05 mM, 0,025 mM and 0,1 mM) added to basal germination medium (15% sucrose + 1% agar + 100 ppm Boric acid) were tested for determining the effects on pollen germination of olive cultivars. Basal media was used for Control treatment. In terms of pollen germination media, pollen germination levels were increased with lower putrescine and higher spermine levels. In Sayfi olive cultivar, while pollen viability rate was 42,74%, pollen germination was 0,00% in control treatments. However, pollen germination was increased for Sayfi olive cultivar with 0,20 mM and 0,10 mM putrescine (3,64% and 3,40%, respectively) and 0,25 mM, 0,125 mM and 0,05 mM Spermine (12,56%, 4,73% and 3,40%, respectively). In conclusion, polyamine treatments were increased the low germinated cultivars. So, polyamine treatments reveal the potential of the pollen especially in low-germinated pollens.

Genomic and Cytogenetic Analysis of Synthetic Polyploids between Diploid and Tetraploid Cotton (Gossypium) Species.

Cotton (Gossypium spp.) is the most important natural fiber source in the world. The genetic potential of cotton can be successfully and efficiently exploited by identifying and solving the complex fundamental problems of systematics, evolution, and phylogeny, based on interspecific hybridization of cotton. This study describes the results of interspecific hybridization of G. herbaceum L. (A1-genome) and G. mustelinum Miers ex Watt (AD4-genome) species, obtaining fertile hybrids through synthetic polyploidization of otherwise sterile triploid forms with colchicine (C22H25NO6) treatment. The fertile F1C hybrids were produced from five different cross combinations: (1) G. herbaceum subsp. frutescens × G. mustelinum; (2) G. herbaceum subsp. pseudoarboreum × G. mustelinum; (3) G. herbaceum subsp. pseudoarboreum f. harga × G. mustelinum; (4) G. herbaceum subsp. africanum × G. mustelinum; (5) G. herbaceum subsp. euherbaceum (variety A-833) × G. mustelinum. Cytogenetic analysis discovered normal conjugation of bivalent chromosomes in addition to univalent, open, and closed ring-shaped quadrivalent chromosomes at the stage of metaphase I in the F1C and F2C hybrids. The setting of hybrid bolls obtained as a result of these crosses ranged from 13.8-92.2%, the fertility of seeds in hybrid bolls from 9.7-16.3%, and the pollen viability rates from 36.6-63.8%. Two transgressive plants with long fiber of 35.1-37.0 mm and one plant with extra-long fiber of 39.1-41.0 mm were identified in the F2C progeny of G. herbaceum subsp. frutescens × G. mustelinum cross. Phylogenetic analysis with 72 SSR markers that detect genomic changes showed that tetraploid hybrids derived from the G. herbaceum × G. mustelinum were closer to the species G. mustelinum. The G. herbaceum subsp. frutescens was closer to the cultivated form, and its subsp. africanum was closer to the wild form. New knowledge of the interspecific hybridization and synthetic polyploidization was developed for understanding the genetic mechanisms of the evolution of tetraploid cotton during speciation. The synthetic polyploids of cotton obtained in this study would provide beneficial genes for developing new cotton varieties of the G. hirsutum species, with high-quality cotton fiber and strong tolerance to biotic or abiotic stress. In particular, the introduction of these polyploids to conventional and molecular breeding can serve as a bridge of transferring valuable genes related to high-quality fiber and stress tolerance from different cotton species to the new cultivars.

DETERMINATION OF POLLEN VIABILITY AND POLLEN GERMINATION CHARACTERISTICS OF SOME SHARKA DISEASE RESISTANT APRICOT CULTIVARS

Turkey is leading the apricot production in the world and also has an important genetic diversity. With the advantage of having different ecological conditions, apricots are produced for different purposes (early table, table, jam, dry). Biotic and abiotic stress factors affect the apricot production of important value, causing yield and quality losses. Apricots’ most important problems in breeding are low fruit yield, spring late frosts, and self-incompatibility in some cultivar, diseases and pests. In these factors, Plum Pox Virus (PPV) the agent of the sharka disease is the most important disease in the apricot and stone fruits with the lost odf production and social effects it made. The best solution for this disease is using resistant cultivars in production. At this point, breeding programs especially including the sharka resistant cultivars are important. For breeding programs, determining pollinator cultivars' pollen quality parameters is important. In this study, pollen viability and pollen germination parameters are determined for “Stark Early Orange” (SEO), “Harleyne”, “Harcot” and “Zard” cultivars. These cultivars are resistant to sharka and may be used in breeding studies as pollinators. Pollen viability was determined with 2,3,5-Triphenyltetrazolium chloride (TTC) and pollen germination was determined with agar in the Petri (1% Agarose and 10% sucrose) method. The cultivar with the highest pollen viability rate (57.8%) is SEO. “Harcot” had the least amount of pollen viable with 28.3%. “Harleyne” cultivar had the best germination rate with 69.8%. Harcot had the lowest pollen germination rate (19.8%). According to the results, there were significant differences among cultivars in the pollen viability and germination rates.

Pollen Viability and Germination Levels with Amount of Pollen Production of Some Important Olive Cultivars in Türkiye

This research was carried out to determine the pollination abilities of Domat, Gemlik and Sarı Ulak olive cultivars. Pollen viability rate, germination rate and amount of pollen production were examined during the periods when 25%, 50% and 75% of the flowers were opened. According to the results obtained from three years’ experimental study, the highest percentages of pollen viability were found in Gemlik (81.51%) and Domat (81.50%), whereas Sarı Ulak cultivar (77.41%) showed the lowest viability. In pollen germination percentages, the highest values on the basis of cultivars were determined 59.85% (Domat), 59.74% (Gemlik) and 52.12% (Sarı Ulak). The highest amount of pollen production in a flower was found in the Sarı Ulak cultivar (329,046) while it was followed by Domat (319,693) and Gemlik (306,385). Despite the high pollen production in Sarı Ulak cultivar, the pollen viability and germination rates were found to be low. In Gemlik and Domat cultivars, all values were obtained relatively near. In addition, it had been noted that the values related to pollen viability, germination and production amount were higher during 50% and 75% flowering periods than 25%.

Evaluation of Growth and Pollen Viability (Fertility) in Relation to Fruit Set among Five Varieties of Tomato

The evaluation of pollen viability and fruit setting capacity are two essential criteria for pollinator’s characterization. This study was carried out to evaluate pollen Fertility/ viability in five Varieties of Tomatoes. We analyzed the viability of pollen grains of five different varieties of tomatoes grown in ITM University, Gwalior, Madhya Pradesh, India. Aceto- carmine method is used to estimate pollen viability. The germination percentage, pollen viability and Fruit setting rate were recorded at different stages respectively. Pollen viability in relation to fruit set was analyzed while growth parameters and fruit yield per plant of each variety were also collected and analyzed. Results displayed that the highest pollen viability rate (100%) was obtained in SWEAKAR-448 Variety followed by Arka Vikas (95%), ARJUN-135 (93%), 9005-SIRI (90%) and PKM-1 (80%). The highest percentage of germination (95%) was shown by 9005-SIRI Variety and maximum fruit setting (15-20 Fruits per plant) was recorded in the SWEAKAR-448 Variety. The results showed significant vegetative growth variations and correlations between pollen viability and fruit setting characters. In addition, it was found a noticeable variation in Pollen viability/fertility, was not proportional to fruit setting percentage. In general Pollen viability was directly linked to fruit set, whereas formation and fruit set were not in the tomato varieties that were investigated. Pollen viability was high, which was accompanied through a reduction in the number of fruit sets, fruit size and pollen viability in the field is highly variable, indicating that differences in microenvironment may have a profound effect on fruit setting and pollen viability.

Determination of Self-Compatibility of the 'Arsel' Olive Cultivar Obtained by Hybridization Breeding

This study was aimed to determine the fertilization biology of the 'Arsel' olive cultivar obtained by hybridization breeding. For this reason, treatments of open pollination, cross pollination, and self-pollination were performed for 2 years and self-compatibility and appropriate pollinators of this new cultivar were investigated. Among the varieties included as pollinators (‘Memecik’, ‘Gemlik’, ‘Uslu’, ‘Ayvalık’ and ‘Eğriburun Nizip’), the highest fruit set was achieved with ‘Memecik’ and ‘Gemlik’ varietes in both years (2.64%, 1.37% and 1.75%, 1.39%). For this reason, ‘Memecik’ and ‘Gemlik’ cultivars were the best pollinator for ‘Arsel’ olive was thought. On the other hand, considering the statistical analyzes and productivity index values, ‘Arsel’ variety was found to be self-incompatible. However, the data also indicated that cross pollination was effective in increasing fruit set. Therefore, it is thought that the use of pollinator cultivar in orchard establishment would be beneficial in terms of yield. Pollen viability and germination tests were performed by using 2,3,5 Triphenyl Tetrazolium Chloride (TTC) and agar in petri (15% sucrose + 1% agar + 100 ppm H3BO3) methods in the study. The highest pollen viability rate was observed in ‘Memecik’ cultivar in 2020 and there isn’t statistical differences between olive cultivars in 2018. The highest pollen germination rate was observed in ‘Arsel’ cultivar in 2018. Accordingly, differences were determined between pollen viability and germination rates of examined olive cultivars in terms of years.

Diferentes temperaturas e tempos de armazenamento na qualidade do pólen em variedades de rosas para corte

Abstract Pollen parent is one of the most important factors affecting the seed set in conventional breeding. Pollen quality of pollen parents must be known for success in breeding programs. Breeders also must know how long pollen grains keep their viability to overcome geographical distance and the difference in blooming times among parents. This study was conducted to find out the viability, germination rate, and duration of the keeping viability of pollen of rose varieties being kept for 0, 4, 8, 16, 24 hours at 24 ºC and 0, 1, 2, 3, 4, 5 days at 4 ºC. The pollen of the Inferno, Layla, First Red, and Myrna varieties were used as plant material. The IKI and petri dishes methods were used to determine pollen quality. The results showed that the viable pollen rate of varieties varied between 41.1% and 49.9%, whereas the germination rate was 3.8% and 29.9% and morphological pollen rate was 71.8% and 88.7%. In all varieties, viability, germination rate and morphological normal pollen rate decreased over time both kept at 24 ºC and 4 ºC, but fresh pollen lost its quality faster than pollen stored. Fresh pollen viability rate decreased by 11.9% and 25.6% at the end of 24 hours, whereas only it decreased by 10.4%-22.6% on 1st day of storage. The reduction in germination ability in Layla, Inferno and Myrna was over 60.0% on the 5th day, while it was found less than 50.0% in First Red. The decrease in morphologically normal pollen ratio was found statistically significant in both temperature treatments, except for Layla. As it is clear, the pollen quality was significantly affected by variety, storage/holding time, and conditions. It’s recommended to use stored pollen in breeding programs. Although it varies according to the varieties, the rose pollen should be use by keeping at 4 ºC between 2-5 days.

The Effect of Temperature and Growth Regulators on Callus Induction in Watermelon Anthers

Callus induction is one of the pathways required for haploid plant regeneration through anther culture. Pollen viability, as well as the effect of growth regulators and cold pretreatment on anthers of two watermelon lines (Smile and Sugar Baby) to induce callus formation were herein evaluated. Pollen viability was estimated through the staining technique using 2% acetic carmine. Male flower buds were collected and disinfested to allow removal anthers. These anthers were placed on Murashige and Skoog medium, which was supplemented with 2,4-dichlorophenoxyacetic (2,4-D) at 0.0, 0.5, 1.0, 2.0 or 5.0 ?M or with 6-benzylaminopurine at 0.0, 0.5, 1.0, 1.5, or 2.0 ?M, in combination with 2.0 ?M of 2,4-dichlorophenoxyacetic. Anthers were pretreated at 4 °C, for two days and then placed in vitro. Both watermelon lines provided high pollen viability rates (from 93 to 98%). The 2.0 and 5.0 ?M concentrations of 2,4-D stimulated higher friable callus formation. The optimal concentration of 2,4-D was estimated at 3.78 ?M and 4.17 ?M, which had callus induction rates of 64% and 52%, respectively. The combination of 2.0 ?M of 2,4-D and 6-benzylaminopurine did not lead to increased anther response to callus induction. The pre-treatment applied to flower buds at 4 °C enabled callus induction and the anther response to callus induction was genotype-dependent.

Reproductive biology, phenology, pollen viability and germinability in Kersting's groundnut (Macrotyloma geocarpum (Harms) Maréchal & Baudet, Fabaceae)

Knowledge gap on the reproductive biology of orphan crops is a major challenge to their cultivar development and genetic improvement. This study described the reproductive organs and phenology, assessed receptivity of stigma versus anther dehiscence, and examined pollen viability and germination in Kersting's groundnut. Experiments were conducted on nine morphotypes in a randomized complete block design with three replications in a screenhouse. Phenological observations were made on 1026 flower buds. Anther dehiscence was determined through microscopic observations while receptivity of the stigma was assessed using the hydrogen peroxide test. Pollen viability was assayed using histochemical staining. In vitro germination and pollen tube growth were assessed for up to 72h. Flowers were bisexual and incompletely protogynous, and spontaneous self-pollination was favoured by style bending. Flowering and fruiting were classified into six developmental stages each. Timing of all stages differed significantly (P<0.001) among morphotypes. The stigma was receptive 1-2 days before anther dehiscence and remained so until each flower wilted. Anthesis started 3 days from young bud appearance and lasted between 2–4 days depending on the morphotype. Pollen viability rates were very high (88–98%) and differed among morphotypes (P<0.001). Pollen germination rates were low (8–37%) and varied among morphotypes and anthesis stages (P<0.05). Pollen tube growth varied significantly among morphotypes, anthesis stages and incubation time. The morphotype ZHLA-2 exhibited the highest reproductive vigour and could be recommended as pollen donor for hybridization. The study provides information on the best time and stage for emasculation and is expected to help breeders optimise a hybridisation protocol.

A cytogenetic and pollen study of annual Medicago species from Soummam Valley (Northeastern of Algeria)

Abstract This paper reports a cytogenetic study of eight Medicago L. species sampled from the Soummam Valley (northeastern Algeria). Chromosome numbers and meiosis irregularities during microsporogenesis were explored. Pollen viability rate and pollen size were also examined. The studied taxa are diploid and display biva-lent pairing and regular chromosome segregation during meiosis. Although meiosis appears regular, some anomalies were detected in relatively high cumulated rates (14.66%–26.14%). The most common meiotic abnormality examined here is related to cytomixis (from 14.66% in M. littoralis to 25.83% in M. laciniata). Other anomalies were also detected, including chromatic bridges, asynchronous divisions, micronuclei and multipolar cells. Consequently, the species exhibited varying percentages of pollen viability (from 70.11% in M. laciniata to 99.14% in M. littoralis). Pollen viability was negatively correlated with meiotic abnormalities (Pearson correlation coefficient R = −0.72, p = 0.043). The pollen grains were also heterogeneous in size. Medicago truncatula Gaertn. and M. laciniata (L.) Miller presented the most variable pollen size (relative standard deviation exceeding 19%). Medicago littoralis is distinguished from other species by possessing homogeneous and large sized pollen (relative standard deviation RSD = 6.73 %). The cytogenetic and pollen data provided by this study are discussed in the context of species systematics and in the perspective of genetic improvement.

Adana Ekolojik Koşullarında Yetiştirilen Bazı Pikan Cevizi Çeşitlerinde Çiçeklenme Zamanları ve Çiçek Tozu Özelliklerinin Belirlenmesi

Bu çalışmada çiçeklenme açısından monoik bitki özelliği gösteren pikan cevizinde, Adana ekolojik koşullarında dişi ve erkek çiçeklerin fonksiyonel olma zamanlarının belirlenmesi ve çiçek tozu canlılık düzeyleri, normal gelişmiş çiçek tozu oranları ve çiçek tozu üretim miktarlarının saptanması amaçlanmıştır. Çalışmada Coctaw, Comanche, Harris Super, Hastings, İdeal, Mahan, Royal, Shawnee, Texhan, Western ve Wichita olmak üzere 11 pikan cevizi çeşidi kullanılmıştır. Çiçeklenme zamanı yönünden denemeye alınan çeşitlerde homogami, protandri, kısmi protandri ve kısmi protogini özellikleri görülmüştür. Erkek ve dişi çiçeklerde çiçeklenme zamanları 2016 yılında 3-20 Mayıs, 2017 yılında ise 30 Nisan-18 Mayıs tarihleri arasında gerçekleşmiştir. Çiçek tozu canlılık değerleri tüm çeşitlerde oldukça yüksek düzeylerde bulunmuş, ancak 2017 yılında 2016 yılına göre biraz daha düşük düzeylerde olduğu belirlenmiştir. Çiçek tozu canlılık değerlerinin her iki yılda da en düşük Hastings çeşidinden (%60,0 ve %61,6), en yüksek ise 2016 yılında Shawnee (%89,1) ve 2017 yılında Mahan (%87,7) çeşitlerinden elde edildiği saptanmıştır. Tüm çeşitler için normal gelişmiş çiçek tozu oranları yeterli bulunmuş olup, söz konusu değerlerin 2016 yılında %92,30 ile %98,42 arasında, 2017 yılında ise %90,20 ile %97,24 arasında değişim gösterdiği belirlenmiştir. Çiçek tozu üretim miktarları bakımından ise çeşitlere göre önemli düzeyde farklılıklar bulunmuştur. Bir salkımdaki çiçek tozu sayısı 2016 yılında 3.512.382 ile 11.097.407 adet arasında, 2017 yılında ise 6.101.233 ile 14.958.453 adet arasında değişmiştir.

Bazı Kayısı Çeşitlerinin Çiçek Tozu ve Döllenme Performanslarının Belirlenmesi

In fruit species, suitable pollinator variety and its pollen quality are effective on fruit setting and as a result, increase the productivity can be provided. For this purpose, some apricot varieties (Iğdır, Tokaloğlu, Precoce de Tyrinthe, Şekerpare, Kabaaşı and Hacıhaliloğlu) were investigated in two different ecology. According to this, pollen viability rates of Precoce de Tyrinthe and Şekerpare varieties were found high, while Kabaaşı variety was low. The pollen production was determined to be high in Malatya although it differed according to the varieties. In İzmir ecology, it was found out that Precoce de Tyrinthe cultivar is appropriate in addition Iğdır variety with appropriate pollinators (Şekerpare and Tokaloğlu) will be possible to grow in high altitude regions that meet chilling requirements. In Malatya ecology, productivity can be increased with all varieties examined depending on pollinators.

Ionizing Radiation from Chernobyl and the Fraction of Viable Pollen

Pollen viability is an important component of reproductive success, with inviable pollen causing failure of reproduction. Pollen grains have evolved mechanisms to avoid negative impacts of adverse environmental conditions on viability, including the ability to sustain ionizing radiation and repair DNA. We assessed the viability of 109,000 pollen grains representing 675 pollen samples from 111 species of plants in Chernobyl across radiation gradients that spanned three orders of magnitude. We found a statistically significant but small and negative main effect of radiation on pollen viability rates across species (Pearson’s r = 0.20). Ploidy level and the number of nucleate cells (two vs. three) were the only variables that influenced the strength of the effect of radiation on pollen viability, as reflected by significant interactions between these two variables and background radiation, while there were no significant effects of genome size, pollen aperture type, life cycle duration, or pollination agent ...

&lt;b&gt;Intra-inflorescence pollen viability in accessions of &lt;i&gt;Brachiaria ruziziensis&lt;/i&gt;

Knowledge about the pollen viability is important to ensure success in controlled hybridizations and, consequently, support breeding programs. The aims of this study were to evaluate the pollen viability in progenies of artificially induced tetraploid accessions of Brachiaria ruziziensis , and to verify if the position of the flower buds on the raceme affects the pollen viability rate. Staining of aborted and non-aborted pollen (Alexander’s technique) was used to determine the viability of the pollen grains. Tetraploid accessions of B. ruziziensis plants had high pollen viability (x = 76.8% to x = 99.6%). Some of these plants had viability rates similar to diploid B. ruziziensis , showing that the induction of chromosome duplication by colchicine did not result in abnormalities in production and morphology of pollen grains. Pollen grains from middle and apical regions of the raceme presented higher viability rates (x = 97.9% and x = 97.7% respectively). The viability of pollen grains in artificially induced tetraploid accessions of B. ruziziensis plants was high, which may favor obtaining fertile descendants in possible crosses

An improved method to obtain novel mutants in Cucurbita pepo by pollen viability

A new genetic resource for Cucurbita pepo has been developed with chemically induced mutagenesis. The seeds of the zucchini cultivar MU-CU16 were treated with 40mM–80mM ethyl methanesulfonate (EMS), reaching high germination rates between 70 and 85%. However, most plants of those M1 populations did not produce offspring, and the fertility rates were lower in plants treated with higher concentrations of EMS. Once we established that visual flower abnormality rates were not sufficient to explain low fruit yield, pollen viability was analysed with fluorochromatic reaction. Compared with untreated plants, treatment with EMS produced a substantial decrease in pollen viability, and only the group of plants with pollen viability rates higher than 45% yielded nearly 70% of fruits with seeds. Therefore, the main issues to be addressed for developing mutant lines in this species are to increase the number of mutations in the genome and to increase the number of mutant lines with sufficient fertility. In this case, the early plantlet selection for high pollen viability carried out as part of this work represents a useful tool for use in future breeding programs by mutagenesis, allowing an increase of up to 40% in the production of mutant lines for a dosage of 65mM EMS.

Assessment of Pollen Viability, Germination, and Tube Growth in Eight Tunisian Caprifig (Ficus caricaL.) Cultivars

The evaluation of pollen viability and its germination capacity are two essential criteria for pollinator’s characterization. This study was carried out to evaluate pollen quality of eight caprifigs grown in the center-east and north-west of Tunisia. Two colorimetric tests 2,3,5-triphenyl tetrazolium chloride (TTC) and acetocarmine were used to estimate pollen viability. Germination rate and pollen tube growth in a culture medium containing 5% sucrose, 5 ppm boric acid (H3BO3) and 1% agar were registered after 24, 48, and 72 hours (H) of incubation. Results showed that the highest pollen viability rate (84%) was obtained by TTC test in caprifig Assafri, followed by Jrani (80.2%), Djebba 2 (77.8%), and Djebba 1 (73.6%). That of other caprifigs did not exceed 50% for the two tests. In all caprifig types, germination rate and pollen tube growth varied according to the incubation period. The highest percentage of germination (72%) and maximum pollen tube length (960 μm) were recorded after 72 H of incubation in caprifigs Assafri and Jrani, respectively. Among the caprifigs studied, four types (Assafri, Jrani, Djebba 1, and Djebba 2) appeared to be suitable pollinators with respect to the criteria investigated.

Biophysical characteristics of maize pollen: Variability during emission and consequences on cross-pollination risks

Modelling of cross-pollination risks using physical-based model of pollen dispersal requires estimations of pollen viability rate as well as settling velocity distribution of viable pollen grains at emission. These two biophysical characteristics are mainly determined by pollen water content. Three years of experiments were carried out to measure biophysical characteristics of pollen at different times of emission within the day. In a first part, we proposed a simple model to predict pollen water content at emission as a function of air vapour pressure deficit. We found that by setting a constant duration of pollen dehydration in the anthers the model predicts accurately pollen water content variations at emission. In a second part, we related pollen water content and settling velocity distribution of viable and non-viable pollen grains. We used with success settling velocity distribution as a proxy to estimate fraction of spheroid pollen, water content distribution of spheroid pollen and pollen viability rate. In addition, we validated with success the estimations of viability rate. In a third part, based on above models, we estimated the effects of air humidity on cross-pollination risks.

English

The fertilization biology of eight sweet cherry cultivars (0900 Ziraat, Lambert, Sunburst, Lapins, Starks Gold, Bing, Chelan and Summit) was studied. Pollen viability was determined with triphenyl tetrazolium chloride (TTC) and fluorescein diacetate (FDA) tests. Pollen germination tests were carried out by hanging drop method on 0, 5, 10, 15 and 20% sucrose solutions. Pollen quantity and pollen morpholo-gical homogeny were determined by hemocytometry method. Pollen tube growth and fruit set ratios of open-pollinated and self-pollinated flowers were also explored. Using TTC and FDA tests, the highest pollen viability rate was obtained with cultivar Sunburst; however, higher pollen germination ratios were obtained with cultivar Lapins and Bing. Starks Gold and Summit cultivars produced more amount of pollen than the other cultivars. A high pollen morphological homogeny was found for all the cultivars. In self, cross and open pollinations, pollen tubes reached the ovules in 2 to 5 days. The pollen tubes of the self pollinated self-fertile cultivars reached the ovule in a less time. Fruit set ratios of the cross-pollinated combinations varied between 0 and 40%. In comparison with self-incompatible cultivars, fruit set ratios of self-fertile cultivars were higher. &nbsp; Key words:&nbsp;Sweet cherry, pollination, pollen tube growth, fruit set.

Investigations of suitable pollinator for 0900 Ziraat sweet cherry cv.: pollen performance tests, germination tests, germination procedures, in vitro and in vivo pollinations

The objective of this study was to determine suitable cultivars to be used as pollinators for 0900 Ziraat. 0900 Ziraat was used as a female cultivar; Bigarreu Gaucher, Bing, Noble, Starks Gold, Stella, Van, and Vista were used for pollination in the experiments. Starks Gold had the highest values in terms of anther number, average number of pollens per anther, number of pollen per flower and the morphological homogeneity. The pollen viability rates showed significant differences according to stain tests. &lt;i&gt;In vitro&lt;/i&gt; pollen germination in 0.5% agar + 15% sucrose + 5 ppm boric acid medium increased with increasing incubation period, and the highest germination was obtained after 48 hours for all cultivars. In orchard trials parallel to pollen tube growth experiments in the laboratory, 0900 Ziraat &amp;times; Starks Gold combination gave the best fruit set results.