ÖZETDiploid Ingiliz çiminden tetraploid Ingjfiz çiminin elde edilmesi,bunların sitolojik ve morfolojik karakterlerinin mukayesesi gayesiile yapılan bu araştırmada %O,2'lik Kolkisinle 24°C'de muamele edilen1500 fideden % 1.6 oranında tetraploid bitki elde edilmiştir. DiploidL. perenne 2n=14, tetraploidlerde 2n=28 olduğu tesbit edilmiştir.Diploidlerin her genomunda 3 satelitli kromozom bulunmuştur.Kromozomlarm 3 tanesi median, 4 tanesi ise submedian se~lromerlidir.Tetraploid Ingiliz çiminin kromozom yapılan ve büyüklükleri diploidIerdenfarklı olmayıp sadece tetraploidlerde kromozom sayılandiploidlerin iki mislidir.Diploidlerde diakinez devresinde kromozomlar nı (yedi bivalan),meydana getirmesine karşılık, tetraploidlerde çok karışık kromozombağlantıları bulunmuştur. Kromozomlarm multivalanlar meydanagetirmesi meiozun ,düzensiz seyretmesine sebep olmaktadır, Meiozungayrimuntazamlığı neticesinde fertilite düşmüş ve tohum tutmaoram" azalmıştır.Morfolojik karakterler arasmdaki farklarm ö'nemli olup olmadıklarmıtesbit için "t" kontrolleri yapılmış, genelolarak tetraploidlerinmorfolojik karakterler yo'nünden üstün oldukları tesbit edilmiştir.POSSIBILITIES OF OBTAINING TETRAPLOID PERENNIAL RYEGRASS (Lolium perenne L.) FROM DIPLOID PERENNIAL RYEGRASS AND COMPARISON OF MITOTIC AND MEIOTIC CHROMOSOMES AND SOME MORPHOLOGICAL CHARACTERISTICS OF THESE PLANTSThe results of these experimentsconducted to obtaine tetrapIoid perennialryegrass (lLJlium pereııne L.),and to compare mitotic, meiotic chromosomesand morphologicaI charactersof these two plant types, can be summarizedas folIows::' ı. To ,obtaine tetrapIoids, 1500diploid perennia) ryegrass seeds weregenninated at 24°C, in gerıninationchamber. Before the emergence of firstleaf from coleoptile, seedlings were putinto 0.2 %aquecus colchicine solution,at 25Co, for three hours, After then,the seedlings which had been washed6 times, were put in the germinationchamber for }-4 days -and then transferedtonat boxes. At the end of twomonths, the survivors wer traasplantedto pots. Consequent1y, 1.6 % of theoriginal seeds employed, were obtainedas tetrapIoid 'perennial rye gıass.2. it was determined tha~ <tiploidperennia) ryegrass had a chfomosomenumber of 211 =14. In each genome.three chfomosomes had satellites. Threechromosomes had median and fourchfomosomes had submedian centromeres.3. No differences couId be foundbetween the caryotypes of diploidsand artificial tetıaploids. But, the numberof chromosomes in artificial tetrapIoidswere doubled (2n = 28).4. In <tiploids, at the stage~, diakinesisand metaphase I, chromosomes were128found to be in the form of 7 II. Thus, the the meiotic division was normal;conceqauntely normal poııen grainswere produced, and fertility was high.5 In diakninesis and metaphase istages of the tetraploıds, paiıing ofthe chromosomes varıed very muchThe multi:valent formations causedabnorlmalities in meiotİc divisionsThe pairing forms of the 165 poIlenmotheı cell~ studied, were as fol1ows:15 %2 II + 6 LV, 48 % 4 II + 5 ıv.16 % 6 II + 4 IV, 16 % 8Il + 3 IVIn addition t9 these uni and multivalent chıomosames were found in theratio of 5 % Because of the abnormalities in the meiotic division, feıtilityand seed set were low6 The differences between themorphological characters were tested,using "t" test As a result, length andwidth of polIen grains, of the stomata,of glumes, of paleas, the number ofnowers p~r spikelet, thickness andwidth ot leaves of the tetraploid weregreater than that of the diploids andthe differences were significant at 1 'voleveL. The length of the leaves oftetraploids significant1y greater than thatof <tiploids, at 5 % leveL. The numberof spikelets and tillers were significantlyhigher in <Jiploids, at 5 % level Nosignificant <tifferences were found inthe length of rachis and compactnessof the spike between diploids and tetrapıoidswere faund.