• Volume 92, Issue 4

      August 1983,   pages  313-371

    • Population dynamics ofImperata cylindrica (L.) Beauv. var. major related to slash and burn agriculture (jhum) in North Eastern India

      SPS Kushwaha PS Ramakrishnan RS Tripathi

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      Imperata cylindrica (L.) Beauv. var. major is an early successional weed coming up in abandoned fallows after slash and burn agriculture in the north-eastern hill region of India. This study is concerned with the population dynamics and reproductive potential of this species in successional communities. Natural regeneration through seeds occurred only in freshly burnt or cüpped fallows though none of the seedlings survived. Natural regeneration was mainly through tillers which declined sharply in older fallows. As a result the species was completely eliminated in fallows older than 5 yrs. This pattern of behaviour of the species has been related to the changing micro-environmental conditions in the developing communities.

    • Influence of potassium nutrition on stomatal behaviour, transpiration rate and leaf water potential of pigeon pea (Cajanus cajan (L.) Millsp.) in sand culture

      K Venkateswara Rao K xxxV Madhava Rao

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      Pipeon pea seedlings were grown in sand culture using Hoagland solution with four levels of potassium. All measurements were made up to 37-day old seedlings. The influence of potassium nutrition on stomatal behaviour, transpiration rate and leaf water potential were observed and results are reported here.

    • Interspecific differences in the constituents of essential oils ofCymbopogon

      G Rajendrudu V S Rama Das

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      Gas chromatography of essential oils ofCymbopogon showed striking interspecific differences in their major constituents. The two species of lemongrass,C. flexuosus andC. pendulus contained large amounts of citral while the citronella grass species,C. nardus andC. winterianus showed comparable amounts of geraniol, citronellal and citronellol. The essential oil ofC. martini was composed only of geraniol and citronellol and was therefore quite different to the other species. The gas chromatography profiles enable the identification of various species yielding essential oils characterised by their specific constituents.

    • Microbiota from the early precambrian of south India: Evolutionary significance and perspectives of biostratigraphy

      Alexander S Lopuchin S Sambe Gowda

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      Paleobiological study of the Dodguni chert and quartzite-like sandstone from the Dharvar Sedimentary Complex has shown the presence of numerous microorganisms of bacterial appearance. The possibility of contamination is doubtful as the rocks are characterized by great compactness without any joints. The microbiota is syngenetic. Morphologically they are represented by two varieties—coccoidal and filamentous forms which are found as typical colonial groupings. In some of the microorganisms the stages of development from reproductive cells to mature colony are seen. The symbiosis of filamentous forms of life with the colonies of coccoidal organisms is observed. Microfossils are reported from the light-coloured cherts and grey quartzite-sandstones. They are represented by 3 new genera which include 4 new species. Besides 3 new species referred to the generaGunflintia Barghoorn,Eoastrion Barghoorn andVeteronostocale Schopf et Blacic are described. One species is identified withGunflintia minuta Barghoorn. In the light coloured cherts the alga-like microfossils represented by one new genusDodgunia are prevailing. In grey quartzite-sandstone microfossils are more diverse and are represented by two new genera hypothetically of bacterial nature. The complex of Dodguni microflora is of great interest for Precambrian palaeonthology since it occupies more ancient position when compared to Gunflint microbiota. The existence of representatives of genusGunflintia in the Dodguni microbiota indicates certain evolutionary succession between these microbiotas.

    • Notes on the genusGlochidion JR and G Forst. (Euphorbiaceae)

      N P Balakrishnan T Chakrabarty

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      An interesting new species,Glochidion subsessile Balakr. and T. Chakrab. and a new subspecies,G. brunneum Hook. f. ssp.andamanicum Balakr. and T. Chakrab. (Euphorbiaceae) are described from the Andaman and Nicobar Islands.g. sumatranum Miq. is reported for the first time from India.

    • Notes on the genusCroton L. (Euphorbiaceae)

      T Chakrabarty N P Balakrishnan

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      The paper describes two new speciesCroton calderi andC. meeboldianus as well as a new variety and a new record from Burma. Another newC. chittagongensis from Bangladesh is also described.

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