Bahram Dehdar Masjedlou 1 Alireza Motallebi Azar 2 Partial Root-zone Drying Irrigation Comparison of two method to evaluate pollen fertility of potato(S.tuberosum L.) cultivars Summary The main obstacle in breeding potato (Solanum tuberosum L.) tetraploids is the sever limitation of male fertility. In potato breeding programs, determining pollen viability is crucial to start crossing plants , achieve successful hybridizations and obtain hybrid seeds. Two methods were used to determine pollen viability: Acetocarmine glycerol gelly test to pollen staining and in vitro pollen germination test. The results showed Acetocarmine glycerol gelly test is appropriate method for male fertility screening in studied cultivars. Results of experiment showed that average percentage of ‘good’ pollens in staining with acetocarmine treatment was 32% higher than in vitro germination method. Among genotypes kizer Cvs with 55% in staining with acetocarmine and 18% in in vitro germination methods was the best genotypes. In this method abnormalities such as tetrads or grains with four cores indicates that infertile. Results Results of experiment showed that average percentage of ‘good’ pollens in staining with acetocarmine treatment was 32% higher than in vitro germination method. This method is very quick and suitable for large numbers of routine observations(Fig.2). The results of pollen staining by CAA correlated with pollen tube growth in vitro germination. A significant difference at 1% level was obtained among genotypes, pollen viability treatments, cultivars and interaction between them. Among genotypes kizer Cvs with 55% in staining with acetocarmine and 18% in in vitro germination methods was the best genotypes(Fig.2).   Bahram Dehdar Masjedlou 1 Alireza Motallebi Azar 2 Panahandeh Jaber2 Introduction Pollen sterility is the most important obstacle to sexual recombination of potato (Solanum tuberosum L.) Indirect methods to estimate the germination power of pollen samples are important for a quick prediction of results from crosses (Ross,1986).In vitro culture of pollen tubes is a convenient way to distinguish inviable pollen from stylar incompatibilities which prevent pollen tube growth in vivo(Bamberg and Hanneman,1991).Determination of pollen germination in vitro is one of the most important direct methods, giving results which as a rule correspond with actual crossing results. But this method is more time-consuming than staining methods while the medium used mostly is sub-optimal. On the other hand, in vitro germination depends on the environmental condition, pollen maturity, composition and PH of the medium, thus it is necessary to determine optimum conditions for pollen germination. As an indirect method, staining with acetocarmine is a common pollen viability test (Gastelo and Bastos,2014).It is recommended simultaneously use several tests to reflect pollen performance.The present study aimed to improve techniques for obtaining higher quantity and quality of potato pollen with low inputs.So this study was done to compare the effects of in vitro germination and pollen staining methods. 1Phd student of Olericulture, Dept of Horticulture, Faculty of Agricultue, University of Tabriz, 51666-14766, Tabriz, Iran 2 Assos,Assist Prof,Dept of Horticulture, Faculty of Agricultue, University of Tabriz, 51666-14766, Tabriz, Iran good pollen% Figure 2 - Effect of two method on the percentage of good pollen in 6 genotypes of S.tuberosum L. Conclusions When microscopic observation of styles indicates that pollen tube do not penetrate,it is desirable to know whether this is due to stylar incompability or to otherwise inviable pollen. In potato breeding work, quick information is often needed about the fertility of pollen samples available for pollination. In these cases staining with acetocarmine test is recommended for use in screening pollen fertility via pollen viability. Figure 1. Comparing -Observation of pollen germination in the culture medium (left) and pollen stains using Acetocarmine Gelycerol Jelly(right and center). Materials and Methods The pollen used in this experiment was 5 commercial cultivars (Agria, Arnova, Sinora, Satina, Kizer and 397045100 hybrid clones from Solanum tuberosum L. The pollen viability tests were performed as follows: a) Assessment of pollen Stainability by acetocarmine (CAA-Test).Pollen samples of each genotype were stained with aceto carmine solution (0.2 g carmine and 100ml 45% glacial acetic acid in distilled water) and observed under an light microscope (100X). More than 300 grains were counted in at least four randomly taken visual fields. Pollen grains that were fully stained, plump and well-defined contours were considered as viable, whereas those that were poorly (or not) stained, and/or irregularly shaped were considered as unviable. Average viability was calculated for each evaluated genotypes. b) Assessment of rates of in vitro germination of pollen (PG- test). The culture medium used for germination and growing of the pollinic tubes in potato contains sucrose, boric acid and polysorbate 20 (Tween 20). Medium distributed in the 5.5 centimeter petri dish and small amounts of pollen spreaded. Humidity chamber prepared, by covering the petri dishes with the lid and a filter paper moistened with distilled water, then placed at room temperature 20-24 overnight. A pollen grain was considered to have successfully germinated when the pollen tube length reaches a size equal to or greater than the diameter of the pollen grain. Results are expressed as the pereentage of the total number of pollen grains per each 10 microscope fields(Fig 1) Bibliography Bamberg,JB. and RE,Hanneman.1991.An effective method for culturing pollen tubers of potato.American Potato Journal.68:373-379. Gastelo, M and G Bastos. 2014. Pollen viability assessment. CIP publication. 5 pp. Ross,H.1986. Potato breeding – problem and prespectives.Ed.Paul parey ,Berlin,Hamburg (advanced in plant breeding,13) .132 pp.