• V K Singhal

      Articles written in Proceedings – Plant Sciences

    • Cytopalynology of some members of Rutaceae

      V K Singhal B S Gill S S Bir

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      Cytopalynology of 13 species of the family Rutaceae from North and Central India do not reveal any correlation between polyploidy and pollen size. Partial pollen malformation in certain species does not seem to be due to detectable cytological reasons. Multivalent formation in some trees ofCitrus jambhiri (2n=18) is due to reciprocal translocations. The newly counted species,C. jambhiri (2n=18) and the monotypic genusLimonia (L. crenulata,n=9) and all other species except forZanthoxylum armatum (n=33) are based onx=9. Though the family is polybasic,x=9 appear to be its original based number. The chromosomal heterogeneity in the family (2n=14–162) coupled with dysploid series of base numbers (x=7–19) confirm that polyploidy and aneuploidy have played a considerable role in speciation.

    • Cytology of woody species

      V K Singhal B S Gill S S Bir

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      Cytological studies have been made on 59 woody species of Polypetalae. Two genera (Gynocardia odorata,n=23;Pahudia martabanica,n=12) and 9 species (Talauma candollei,n=19;Cratoxylon polyanthum,n=11;Sterculia villosa,n=20;Grewia hirsuta,n=9;Millettia brandisiana, 2n=22+0−2B;Phanera glauca,n=14;Terminalia oliveri,n=12;Psidium coriaceum, 2n=77;P. pumilum,n=11) are counted for the first time. Additional and/or varied chromosome numbers are recorded for 8 species. Presence ofB-Chromosomes has been detected inCrataeva nurvala (n=13+0−3B),Erythrina caffra (n=21+0−3B) andMillettia brandisiana (2n=22+0−2B). Existence of some multivalents in the tetraploid taxa ofEugenia jambolana (2n=44) andHydnocarpus laurifolia (2n=48) indicates their segmental alloploid nature. But the presence of cent per cent trivalents (11III) in the triploid cytotype ofEugenia uniflora (2n=33) reveals the autotriploid nature. Presence of some univalents in diploid taxa ofMillettia brandisiana (2n=22) may be due to asynapsis and/or desynapsis. Variation in chromosome number inPMCs and some pollen sterility inHydnocarpus kurzii seems to be the consequence of cytomixis. Abnormalities in microsporogenesis in one of the cultivated trees ofFirmiana pallens (2n=40) are due to spindle irregularities.

    • Cytology of woody members of Rosaceae

      V K Singhal B S Gill M S Sidhu

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      Meiotic counts have been made on 16 woody species of the family Rosaceae from Indian forests. Of these,Photinia notoniana (n=17),Rubus gardnerianus (n=28) andSorbus foliolosa (2n=68) are counted for the first time. Besides, the Indian populations ofChaenomeles japonica (n=17),Cotoneaster acuminata andEriobotrya japonica (n=17) are also worked out for the first time. Intraspecific polyploid cytotypes are recorded inPyrus communis (2x, 3x) andRosa leschendultiana (2x, 4x). On the basis of chromosomal associations, the tetraploid cytotypes ofSorbus foliolosa appears to be alloploid in nature whereas the triploid ofPyrus communis show autoploid behaviour. Variation in chromosome number and some pollen sterility in pollen mother cells of meiotically normal diploid individuals ofCotoneaster acuminata (n=17),Prunus domestica ssp.insititia (n=8) andRosa leschenaultiana (n=7) seems to be due to chromatin transfer during cytomixis.

    • Cytological explorations of Indian woody legumes

      V K Singhal B S Gill M S Sidhu

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      Cytological exploration of 47 woody leguminous species have been made from the forests of northern, central and southern India. Of these,Acacia canescens (n=13),Dichrostachys cinerea (n=26),Erythrina caffra (n=21),Millettia brandisiana (n=11),Mucuna hirsuta (n=11),Pahudia martabanica (n=12) andPhanera glauca (n=14) are explored for the first time. Additional and/or variable cytotypes are recorded inBauhinia acuminata (n=13) andProsopis glandulosa (n=28). Existence of B-chromosomes has been recorded inErythrina caffra (n=21+0−3B),Millettia brandisiana (n=11+0−2B),Pongamia pinnata (n=11+0−7B) andTamarindus indica (n=13+0−4B). Besides these cytomorphological variabilities, structural heterozygosity for translocations/inversions (Ougeinia oojeinensis, Pongamia pinnata, Saraca indica) and cytomixis (Caragana brevispina) are also existent.

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