• J G Oke

      Articles written in Proceedings – Section B

    • Chromosome numbers in some species ofDichanthium Willemet, andBothriochloa O. Ktze

      J G Oke

      More Details Abstract Fulltext PDF

      Cytological examination ofD. annulatum, D. caricosum, D. nodosum andB. intermedia was undertaken.

      Meiotic and somatic chromosome numbers observed namelyn = 20 and2n = 40 inD. annulatum are in confirmation with the observations of the previous workers.

      Meiotic and somatic chromosome numbers inD. caricosum have been observed as 20 and 40 respectively for the first time as the somatic number reported by Krishnaswamy (1939) does not agree with the number reported here.

      The somatic chromosome number inD. nodosum is 2n = 40. This is being reported for the first time.

      No polyploidy was observed in the forms of the three species ofDichanthium studied.

      InB. intermedia 40 chromosome type is being reported for the first time and the existence of 60 chromosome type is confirmed.

      The existence of polyploidy has been observed inB. intermedia and the increase in chromosome number is associated with the increase in size and other characters.

    • Flowering habits ofDichanthium annulatum, Stapf.,Dichanthium caricosum, A. Camus andBothriochloa intermedia (Br.) A. Camus

      J G Oke

      More Details Abstract Fulltext PDF

      The time interval between the various stages commencing with the appearance of flag-leaf of the boot to complete anthesis of panicle inD. annulatum, D. caricosum andB. intermedia was studied. Detailed study of blooming of florets and dehiscence of anthers ofD. annulatum was also carried out.

      InD. annulatum andD. caricosum a period of two days elapses between complete emergence of panicles out of the boots and the commencement of anthesis thus allowing sufficient time to self and treat number of panicles at a time. InB. intermedia anthesis and dehiscence take place as the panicles emerge out of the boots and thus it is necessary to bag or treat the panicles immediately three or four days after the appearance of flag-leaf.

      A period of 11 days inD. annulatum andD. caricosum and 9 days inB. intermedia is required from the appearance of flag leaf to completion of anthesis.

      InD. annulatum anthesis and dehiscence take place as a rule, during night and early morning between 9p.m. and 4a.m.

      InB. intermedia anthesis of florets and emergence of the panicles out of the boots take place simultaneously bit by bit and takes about 4 days for completion of these two processes. Blooming and dehiscence, however, take place during night and early morning as inD. annulatum.

      D. annulatum, D. caricosum andB. intermedia appear to behave as self-pollinated grass species.

      Laboratory experiments showed thatD. caricosum blooms and dehisces during night and early morning at about the same time asD. annulatum.

    • Natural tetraploidy inCicer arietinum L.

      J G Oke

      More Details Abstract Fulltext PDF

      Cytological observations on the naturally occurring mutant gram have been described. The mutant was found to be an autotetraploid with 2n=32. Some seedlings with one extra chromosome were observed. Occurrence of such extra chromosomes is common in the progenies of autotetraploids.

      Detailed and critical analysis of morphology of the individual chromosomes in the somatic complements of the diploid as well as tetraploid types has been given for the first time.

      Decrease in size of chromosomes with increase in chromosome number was not observed in the case of the mutant studied.

      The coefficient of multivalency was found to be fairly high in the mutant which indicated that continuous selection in the selfed progenies would be necessary for some years.

      Maximum germination of pollen grain was obtained on 12% sugar solution in the case of tetraploid gram and on 71/2% in the case of diploid gram which indicates that the tetraploid gram has higher osmotic pressure indicative of higher concentration of water-soluble cell contents.

    • Chromosome numbers in some species ofIschaemum linn- andSehima forsk. In parts of Western India

      J G Oke

      More Details Abstract Fulltext PDF

      Somatic and meiotic chromosome numbers in 13 species ofIschaemum and two species ofSehima have been reported. Most of these numbers either constitute new reports or a revision of the earlier reports. Basic chromosome number seemed to be 10 inIschaemum andSehima with incidence of polyploidy ranging from diploid to hexaploid forms inIschaemum and diploid to tetraploid forms inSehima.

    • Flowering habits of some species ofIschaemum linn., andSehima forsk., found in parts of western India

      J G Oke

      More Details Abstract Fulltext PDF

      In the 12 species ofIschaemum and two ofSehima studied, anthesis and dehiscence take place between 9 and 10a.m. and again between 4 and 5p.m. each day. Periods and modes of boot and panicle emergence as also the anthesis and dehiscence, however, vary in some detail in different species and their biotypes. These have been presented. Such data are of considerable value in breeding as also in seed production.

    • Biotype differentiation in some species ofDichanthium willemet,Ischaemum linn.,Chrysopogon trin.,Sehima forsk.,Iseilema hack., andHeteropogon pers. found in parts of Western India

      J G Oke

      More Details Abstract Fulltext PDF

      An analysis of intraspecific variations in more important forage grasses of Western India, belonging to the generaDichanthium, Ischaemum, Chrysopogon, Sehima, Iseilema andHeteropogon of the tribeAndropogoneae has been presented. Under the above six genera 23 species were examined which resulted in isolation of 95 biotypes.

    • Karyotypic variations, meiotic behaviour and phylogenetic interrelationships in some species ofIschaemum Linn. andSehima forsk. In parts of Western India

      J G Oke

      More Details Abstract Fulltext PDF

      Observations on the chromosome morphology and standardization of karyotypes of 13 species ofIschaemum and two species ofSehima have been presented. Purely on the basis of comparative morphology these genera seemed to be closely allied. This close affinity is further reflected in respect of their common basic number, general homologies in karyotypes as also broad correspondence in meiotic features. In both the genera there is incidence of polyploidy ranging from diploid (2n=20) to hexaploid (2n=60) forms inIschaemum and diploid (2n=20) to tetraploid (2e=40) forms inSehima. Comparative analysis of meiotic behaviour has suggested high incidence of intraspecific as well as interspecific autopolyploidy. In spite of high polyploidy and irregular meiosis, species in both these genera have retained their constancy and taxonomic individuality through apomixis.

  •  

© 2017-2019 Indian Academy of Sciences, Bengaluru.