• Volume 98, Issue 2

      April 1988,   pages  67-156

    • A new species ofSpegazzinia from Western Australia

      C V Subramanian

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      Hyphomycete collected onXanthorrhoea preissii Endl. (Xanthorrhoeaceae) in western Australia is described as a new species ofSpegazzinia Sacc.,Spegazzinia xanthorrhoeae.

    • Uptake and assimilation of nitrogen by marine diatoms—I. Kinetics of nitrogen uptake

      V Sivasubramanian V N R Rao

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      Axenic cultures of marine diatoms,Achnanthes hauckiana Grun.,Amphora coffeaeformis (Agardh) Kütz.,Fragilaria pinnata Ehr.,Synedra tabulata (Agardh) Kütz.,Thalassiosira weissflogii (Grun.) Fryxell et Hasle (=Thalassiosira fluviatilis Hustedt) andTriceratium dubium Brightwell isolated from tropical waters were used for a comparative study of kinetics of NO3, NO2 and NH4+ uptake. Nitrogen uptake by diatoms in this study followed the classical kinetics reported by previous workers. Diatoms which showed highK3 for NO3 uptake had highK3 for NH4+ and NO2 uptake. But no correlation could be obtained between cell size andK3 for nutrient uptake and an inverse relationship between specific growth rate andK3 was also not obtained. However, there was good correlation between the observedK3 and nutrient status of the habitats from which the diatoms were isolated. Studies on the interactions between NO3, NO2 and NH4+ revealed that NH4+ inhibited both NO2 and NO3 uptake non-competitively whereas NO3 of NO2 inhibited each other in a competitive manner. Inhibition by NO3 of NO2 uptake was greater than the reverse situation.

    • Uptake and assimilation of nitrogen by marine diatoms—II. Kinetics of nitrogen assimilation

      V Sivasubramanian V N R Rao

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      A comparison ofKM values for nitrate and nitrite reductases with uptake capacities of 6 marine diatoms indicated that intracellular accumulation of NO3 and NO2 is necessary for efficient functioning of the enzymes.Amphora coffeaeformis, Thalassiosira weissflogii andSynedra tabulata accumulated very little NO3 whereasTriceratium dubium, Achnanthes hauckiana andFragilaria pinnata accumulated 0·02 to 1· 5mM NO2. Studies with inhibitors of nitrate and nitrite reductase indicated that nitrite reductase could be located i in a different compartment such as chromatophores as in higher plants. NH4+ was also accumulated by the diatoms. Studies on the kinetics of glutamine synthetase and glutamate dehydrogenase indicated that the primary enzyme involved in NH4+ assimilation could be glutamate dehydrogenase, because of its lowKMNH4+ and relatively greater activity than glutamine synthetase. Intracellular analysis of NH4+ revealed that its concentration was well below theKMNH4+ for glutamine synthetase.

    • Diurnal and seasonal variations in the phytoplankton production of lake Kondakarla

      K S N Murthy V Seshavatharam

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      Variations in the phytoplankton production of lake Kondakarla were estimated at two levels (surface and at 1 m depth) during a period of 12 months. The gross production values ranged from 0·10–1·40 mg O2l−1 h−1 at surface and from 0·06–0·73 mg O2l−1 h−1 at 1 m depth. Peak values of gross production occurred between 9–12 h or from 12–15 h during the different months at both the levels. The seasonal variation in gross primary production ranged from 2·70 mg O2l−1 day−1 during January 1984 to 9·42 mg O2l−1 day−1 in September 1983 for surface waters and from 1·60 mg O2l−1 day−1 during September 1983 to 5·40 mg O2l−1 day−1 in February 1984 in waters at 1 m depth. The depth intergrated production varied from 4·08–13·05 g O2m−2 day−1 while the photosynthetic efficiency ranged from 0·580–4·301%.

    • Chemotaxonomic characters in twelve species of the genusPennisetum (Poaceae)

      M V Subba Rao D M Sujatha Y Saideswara Rao V Manga

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      The present study reports some chemotaxonomic characters in 12 species of the genusPennisetum (Poaceae). Distribution pattern of 3 biochemical constituents, viz. phenolic compounds, proteins and esterase isozymes were studied in the leaves of the 12 species, using paper chromatography and polyacrylamide gel electrophoresis. A total of 15 phenolic compounds, 23 protein bands and 19 esterase bands were observed in all these species. Data on these 3 chemotaxonomic characters were subjected to cluster analysis which resulted in grouping the 12 species into 5 clusters.

    • Architectural plasticity of two bamboo species (Nehouzeua dulloa A Camus andDendrocalamus hamiltonii Nees and Arn.) in successional environments in north-east India

      K S Rao P S Ramakrishnan

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      Two bamboo species,Neohouzeua dulloa A Camus andDendrocalamus hamiltonii Nees and Arn. show plasticity in architecture, biomass and nutrient allocation patterns over a successional gradient of up to 60 yr for the former and 25 yr for the latter. However, optimal biomass accumulation rate was attained in a 15 yr old fallow for both species. Maximum elongation and thickness of the zero-order branch (main axis) is attained in a 15 yr old fallow forNeohouzeua dulloa and in a 25 yr old fallow forDendrocalamus hamiltonii. The lower order branches produced on the zero-order branch ofNeohouzeua dulloa are generally sylleptic whereas those ofDendrocalamus hamiltonii are proleptic. Maximum elongation and thickness for the zero-order branch, and least bud dormancy on them occurred in a 15 yr old fallow forNeohouzeua dulloa and in a 25 yr old fallow forDendrocalamus hamiltonii. Dendrocalamus hamiltonii in a 5 yr old fallow had a well developed first-order branch system with diffusely placed lower order branch clusters appearing as if borne on the first-order branch, unlike in older fallows where first-order branch production was continuous and lower order branch clusters appeared as if borne on the zero-order branch itself. In older fallows both species tend to allocate more biomass and nutrients to the below-ground rhizomatous component, as an adaptation for survival and vegetative regeneration after slash and burn disturbance. The growth and architecture of both species are generally geared to capitalize upon the high light regime of the early successional environment, but with a limited ability byNeohouzeua dulloa to tolerate shade.

    • Suitable level of zinc, copper and manganese for mass production of the vesicular arbuscular mycorrhizal fungus,Glomus fasciculatum

      M N Sreenivasa D J Bagyaraj

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      There is no information on the role of micronutrients on the mass production of the vesicular arbuscular mycorrhizal fungi. Hence zinc, copper and managanese at 4 different levels in Ruakura plant nutrient solution viz. 1/4, 1/2 and double the recommended level were studied to select the suitable level for mass production ofGlomus fasciculatum inoculum raised inChloris gayana (Rhodes grass) using perlite: soilrite mix (1:1 by volume). Percentage root colonization, extramatrical chlamydospore number and number of infective propagules per unit weight of the inoculum were maximum at half the recommended level i.e. 0·18, 0·04, 0·73 mM of Zn, Cu and Mn respectively.

    • Cytology and distribution pattern of woody species of Verbenaceae in Palni hills

      G S Chatha S S Bir

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      Studies on the cytology and distribution pattern of 16 woody species of Verbenaceae from Palni hills have shown that: (i) in case ofLantana, the chromosome size is not influenced by increase or decrease in chromosome numbers, (ii) there is no correlation of chromosome size with the habits of different species ofVitex, (iii) transmigration of chromatin material inGmelina arborea, Lantana aculeata andSymphorema polyandrum results in encoutering of abnormal chromosome numbers, (iv) inLantana camara loose or compact association of various groups of chromosomes indicates that genomic constitution of the species is made up of intermingling of different genomes, (v)L.camara (4x) andL. indica (6x) do show the presence of multiple associations in some pollen mother cells which indicate their autoalloploid nature, and (vi) inNyctanthes arbortristis, the correct recorded number is 18 bivalents and the earlier reports of n=22 and n=24 cannot be explained easily.

      The distribution pattern of various species in Palni hills as worked out here shows that in case of theLantana, tetraploid species have widers range of distribution as compared to 2x and 6x ones. The maximum representation of the presently studied species is between 900–1400 m altitudinal zone illustrating that each species is represented in more than one type of forests while overlapping of distribution in different forests is not a rare phenomenon of the investigated taxa.

    • Development of gametophytes, embryogeny and pericarp inGoodyera repens (Orchidaceae, Neottieae)

      Sarvesh Kumar Sood

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      The gametophytes, embryogeny and pericarp of the orchidGoodyera repens are described. The anther wall consists of an epidermis, fibrous endothecium, middle layer and a uniseriate tapetum of binucleate cells. Meiosis is normal. Decussate, isobilateral, linear and tetrahedral pollen tetrads are formed. At shedding the massulae are 2-celled. Ovules are anatropous, bitegmic and tenuinucellate. The inner integrument alone forms the micropyle. Development of the female gametophyte is monosporic. The primary endosperm nucleus degenerates without and division. Development of embryo corresponds to the Asterad type. the mature embryo lacks differentiation. The seeds are minute and nonendospermic. The seed coat is formed entirely by the outer layer of testa.


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