The chromosome number of Abutilon ranadei Woodr. et Stapf.(a winter flowering Abutilon) was 2n=42 diploid (n=21) reported here for the first time.

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As a part of our programme to explore and evaluate genetic diversity of flowering plants of Western Himalayas, at present 180 species of Polypetalae have been cytologically worked out for the first time from District Sirmaur of Himachal Pradesh in the Western Himalayas. New/ varied chromosome numbers are recorded for 37 species (39 cytotypes) belonging to 25 genera of 15 families of polypetalous plants. The taxa being cytologically worked out for the first time on world-wide basis include eight species as Caltha alba (2n=32), Corydalis ramosa (2n=16), Geum elatum (2n=28), Heracleum canescens (2n=22), Pleurospermum brunonis (2n=22), Rhodiola wallichiana (2n=28), Saxifraga parnassifolia (2n=16), and Stellaria semivestita (2n=26). New intraspecific cytoypes have been recorded at present against previously known cytotypes of some soecies on world-wide basis in case of 15 species as, Cassia mimosoides var. wallichiana (2n=32), Duchesnea indica (2n = 28), Geum roylei (2n=28), Impatiens bicornuta (2n=14), I. laxiflora (2n=14, 16), Nasturtium officinale (2n=16), Pimpinella acuminata (2n=18), Potentilla atrosanguinea (2n=28), P. gerardiana (2n=28), Sibbaldia cuneata (2n=28), Sibbaldia micropetala (2n=14, 28), Sida cordifolia (2n=16), Saxifraga diversifolia (2n=16), Stellaria monosperma (2n=26) and Stellaria media (2n=26), Likewise, ten species have been cytologically worked out for the first time from India as: Berberis vulgaris (2n=28), Bergenia ciliata (2n=34), Chaerophyllum aromaticum (2n=22), Epilobium palustre (2n=36), Geranium ocellatum (2n=36), Potentilla argyrophylla (2n=56), Saxifraga brunonis (2n=16), Saxifraga sibirica (2n=16), Sedum multicaule (2n=28), and Thalictrum minus (2n=14) . Moreover for 4 species, varied cytotypes are being reported on India basis as: Potentilla kleiniana (2n=14), Sida cordata (2n=16) Silene vulgaris (2n=48), and Trifolium repens (2n=16).

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Original chromosome counts are reported in 16 populations of Tanactum parthenium Schultz Bip. (Asteraceae) collected from west of Iran. Chromosome numbers in the species were varied from 2n=2x=18 to 2n=4x=36. Ten diploid populations (2n=2x=18) were detected in the studied areas that are accordance with the few prior reports. Three populations with both diploid and tetraploid chromosome number (2n=2x=18 and 36) were identified that is the first report for this species. The results indicated that intraspecific polyploidy was confirmed as the most significant evolutionary trend in chromosome number within this species.

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Autotetraploid Osmunda lancea (2n=4x=88) was produced artificially by apospory. The meiotic chromosome configulation of the autotetraploid O. lancea showed the maximum 21 quadrivalent chromosomes at prophase I, in most of the spore mother cells. Their metaphase I plates additionally showed univalent, bivalent and multivalent chromosomes. Anaphase I and II plates showed frequently laggards. To make the meiosis regularly, the suppression system of multivalent chromosome formation might be obtained in the process of evolution in autoploid ferns in nature. Aposporous sporophytes could not be induced from the autotetraploid O. lancea anymore.

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The present study was undertaken to study the effect of nicotinamide at different concentrations viz.0.5%, 1.0%, 1.5%, 2.0% on root meristems of Cyamopsis tetragonoloba L. Mitotic study reveals various types of chromosomal aberrations like scattering(C-metaphase), precocious, unorientations, laggard, stickiness, bridges etc. Among these scattering was most prominent followed by precocious movement at metaphase and stickiness at anaphase. The AMI is expressed in terms of RDR while the chromosomal abnormalities in terms of RAR. The RDR considerably became more negative and RAR was increased along with increasing doses of nicotinamide. Increase in the negative value of RDR was directly proportional to the severity of the mitotic inhibition. Thus it was found that along with increasing treatment doses of nicotinamide the total abnormality percent increased and the active mitotic index decreased which shows potential toxicity of nicotinamide at their higher doses in this plant.

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