Cytologia 43: 717-725, 1978 Studies on Bulbous Ornamentals I. Karyomorphology of diploid and triploid taxa of Pancratium triflorum Roxb. M. G. Ponnamma Department of Botany, University of Kerala, Kariavattom, Trivandrum, India Received April 25, 1977 Pancratium, a genus belonging to the family Amaryllidaceae is a native of West Indies, Canary Islands and Mediterranean region (Chittenden 1951). Most species of the genus are widely cultivated in the Indo-Bangladesh sub-continent and abroad as horticultural plants (Zaman and Nessa 1974). According to Hooker (1894) and Chittenden (1951) the genus Pancratium contains 12 species. Traub (1962) has reported 20 species in the genus. The cytology of various species of this genus has been worked out previously by Heitz (1926), Fernandes (1930), Inariyama (1937), Sato (1938), Brumfield (1941), Martinoli (1949, 54), Sharma and Ghosh (1954), Sharma and Bal (1956), Con tandriopoulos (1957), Reese (1957), Morton (1965), Kozuharov et al. (1968), Borgen (1969), Fernandes and Queiros (1971) and Zaman and Nessa (1974). The present paper deals with somatic chromosome studies on two cytotypes of Pancratium triflorum of which there is no previous record. Materials and methods Bulbs from wild materials of Pancratium triflorum were collected from Man nady in Quilon District. Root tips were pretreated with .002M. 8 hydroxyquinoline for 2-3 hours, washed and fixed in acetic alcohol (1:3) mixture. A trace of ferric acetate was added to the fixative for better staining. The squash preparations were made in acetocarmine. For meiotic and pollen mitotic studies flower buds taken from the underground bulbs by cutting them open were fixed in 1:3 acetic alcohol mixture and smeared in acetocarmine. Several preparations for each taxa have been studied, but for making idio grams, 5 cells were analysed in detail. Photoidiograms were prepared from photo micrographs by cutting out individual chromosomes, matching them in pairs or triplets as the case might be, on the basis of morphology and arranging in descending order of their length. For the study of chromosome morphology the terminology used by Levan et al. (1964) has been followed. Observations Somatic chromosomes of diploids Root tip cells of plants of Pancratium triflorum collected from Mannady in 718 M. G. Ponnamma Cytologia 43 Figs. 1-3. Mitosis in Pancratium trif1orum. •~1000. 1-2, root tip mitosis (2n=22), pollen mitosis (n=11) of diploid taxon. 3, root tip mitosis of triploid taxon (2n=33). 1978 Studies on Bulbous Ornamentals I 719 Quilon District showed 22 chromosomes (Fig. 1). This is a diploid based on x=11 reported earlier for this genus and is the first report for this species. The chromo somes range in length from 33ƒÊ to 13.4ƒÊ (Table 1) and could be grouped into 11 pairs-four long (33ƒÊ-25ƒÊ), four medium (18.5ƒÊ-15.5ƒÊ) and three comparatively short (15ƒÊ-13.4ƒÊ) (Figs. 4 and 6). The somatic chromosomes were found to belong to the following types: 1. A pair of long chromosomes with median constriction (33ƒÊ). 2. Two pairs of long chromosomes with median constriction (26.5ƒÊ and 25ƒÊ). 3. A pair of long chromosomes with submedian constriction (25ƒÊ). 4. A pair of medium sized chromosomes with submedian constriction (18.5ƒÊ). 5. A pair of medium sized chromosomes with subterminal constriction, having terminal satellite on the short arm (17.5ƒÊ). 6. A pair of medium sized chromosomes with terminal constriction (15.5ƒÊ). 7. A pair of medium sized chromosomes with subterminal constriction and a secondary constriction on its short arm (15.5ƒÊ). Table 1. Details of haploid chromosome set in Pancratium triflorum Roxb. 2n=22 8. Two pairs of comparatively short chromosomes with terminal constriction (15ƒÊ). 9. A pair of chromosomes, shortest of the group with median constriction (13.4ƒÊ). Though a large number of bulbs were dissected and flowers fixed, meiosis could not be studied due to non availability of flower buds in the correct stage. Pre parations of pollen mitosis were obtained showing 11 chromosomes (Fig. 2). Somatic chromosomes of triploids Certain plants collected from the same population showed 33 chromosomes in the somatic cells (Fig. 3). These are triploids based on x=11. A triploid taxon is being reported for the first time in this species as is also the case with the diploid. The basic karyotype of four long, four medium and three comparatively short chromosomes could be recognized in the triploid also. The chromosomes range in length from 25.5ƒÊm to 11ƒÊ (Table 2). The chromosome morphology was 720 M. G. Ponnamma Cytologia 43 exactly similar to that of the diploid taxon, four having median, two with sub median, two with subterminal and three with terminal constrictions. The position of the satellite and secondary constriction was also similar to that in the diploid Figs. 4-5. 4, photoidiogram of diploid taxon of P. triflorum. 5, photoidiogram of triploid taxon of P. triflorum. (Figs. 5 and 7). The total chromatin of the haploid set in the triploid was found to be less than that of the diploid (Fig. 8). 1978 Studies on Bulbous Ornamentals I 721 Discussion Available data on the cytology of the genus Pancratium so far known are sum marised in Table 3. It is seen from the table that most of the investigated species of Table 2. Details of haploid chromosome set in Pancratium triflorum Roxb. 2n=33 Table 3. The chromosome numbers of the genus Pancratium Pancratium are diploids with 2n=22. The present finding of 2n=22 in P. triflorum is in agreement with previous observations of 2n=22 made by Brumfield (1941), 722 M. G. Ponnamma Cytologia 43 Battaglia (1949), Martinoli (1949, 1954), Sharma and Bat (1956), Contandriopoulos (1957), Morton (1965), Borgen (1969), Battacharyya et al. (1971) and Fernandes and Queiros (1971). Heitz (1926) has observed 80-100 somatic chromosomes in P. zeylanicum while Sharma and Bhattacharyya (1960) counted 48 chromosomes for the same species. Inariyama (1937) reported 46 chromosomes in P. speciosum. Battaglia (1949) has found 33 chromosomes in the somatic cells of P. lutea. Sharma Figs. 6-8. 6, idiogram of diploid taxon of P. triflorum. 7, idiogram of triploid taxon of P triflorum. 8, histogram showing length of haploid complement. and Ghosh (1954) have recorded 48 chromosomes for an unidentified Indian species of Pancratium. According to Sharma and Bal (1956) 11 could be considered as constituting the haploid set in this genus; 46 and 48 being derived from 44 (4n). Bose (1962) has suggested 11, 12 and 23 as the basic numbers for Pancratium. Start ing with 11 one gets upto hexaploid types and only diploid and tetraploid types in the 12 series. According to him the somatic number of 46 found in P. speciosum 1978 Studies on Bulbous Ornamentals I 723 by Inariyama (1937) could have originated from a basic number of 23. Zaman and Nessa (1974) have reported 2n=44 chromosomes for P. verecundum and they consider it as a tetraploid based on x=11. The presence of another pentaploid cytotype in the same population with 2n=55 according to them supports the con tention of x=11 for P. verecundum. Reese (1957) has found 66 chromosomes in P. saharae. Thus a polyploid series based on x=11 from diploid to hexaploid with 2n=22, 33, 44, 55 and 66 chromosomes could be traced from previous reports. Present observation of 2n=22 and 33 in members of P. triflorum supplements and confirms the presence of the basic number x=11 in this genus. Sharma and Ghosh (1954) found that the length of individual chromosomes in an unidentified species (2n=48) of Pancratium ranged from 15ƒÊ to 3.3ƒÊ. Zaman and Nessa (1974) observed a range in chromosome length of 14.40ƒÊ to 2.8ƒÊ is in P. verecundum (2n=55) from Bangladesh. According to them although the chro mosomes of the above species differed in morphology from those reported by Sharma and Ghosh (1954), they showed close resemblance in length and therefore the species studied from India and Bangladesh are very closely related. In the case of P. triflorum investigated in the present study, the chromosomes range in length from 33ƒÊ to 13.4ƒÊ in diploids and 25.5ƒÊ to 11ƒÊ in the triploids. The progressive reduction in size of chromosomes in the 2n=33, 2n=48 and 2n=55 species compared to the diploid might be associated with increase in the ploidy level. Reduction in chromosome size with increase in ploidy has been observed in other genera of the family like Hymenocallis (Sharma and Bal 1956, Raina and Khoshoo 1971), and Zephyranthes (Raina and Khoshoo 1971). Zaman and Nessa (1974) observed that all the five chromosomes in the third group of P. verecundum (2n=55) studied by them had secondary constrictions and they took it as an evidence of autopolyploidy. In the present study the satellites were seen in the sixth pair and secondary constrictions in the eighth pair both in the diploid and triploid. This and the complete morphological identity of chromo somes in the two taxa might indicate autoploid nature of the triploid taxon. Summary Somatic chromosomes of two cytotypes of P. triflorum are reported (2n=22 and 2n=33). This is the first report of chromosome number for this species. The position of the satellites and secondary constrictions are the same in both diploids and triploids and on the basis of this and complete morphological identity of the chromosomes an autoploid origin of the triploid is suggested. Acknowledgment The author is deeply indebted to Dr. C. A. Ninan, Professor and Head of the Department of Botany, University of Kerala, Trivandrum, for valuable guidance and encouragement. Financial assistance from U. G. C. is gratefully acknow ledged. 724 M G.