• Volume 92, Issue 5

      October 1983,   pages  373-441

    • Developmental morphology ofNitellopsis obtusa (Desv.) Groves

      S Bharathan

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      The structure and development ofNitellopsis obtusa have been studied in culture. The main features are compared with those of the other members of the Chareae.

    • 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.

    • Hazardous species ofAspergillus ochraceus group in the air of working environments at Mysore

      K B Jayaprakash A Ramalingam

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      Species of theAspergillus ochraceus group were most abundant in the air of a coffee curing works of the seventeen environments studied at Mysore. They also occurred in large numbers in coffee dust, husk samples, sorghum and paddy. Incubating at room temperature (20–25°C) was found most suitable for enumeration of these species. Only 6.6% of the air-borne isolates of the group produced ochratoxin-A. A. ochraceus was the most common species of the group isolated from air and also yielded a greater proportion of toxic isolates.

    • Nitrate and nitrite reduction as influenced by S-(4-chlorobenzyl)-N, N-diethyl thiocarbamate in two tropical weed species

      N V R Reddy K R Ramaiah K B Reddy K R Rao

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      An increase in nitrate reductase activity was observed with a concomitant decrease in nitrite reductase activity in the herbicide treated leaves ofAcalypha indica Linn. andDactyloctenium aegyptium Bauv. This non-photosynthetic selective herbicide has an uncoupler effect similar to that of DNP which in turn enhances the nitrate reductase activity. The generation of NADH linked to the glycolytic process, provides higher levels of NADH for nitrate reduction and its accumulation in treated plants over the control even in darkness.

    • Gibberellin-like substances in seed and leachates of black gram (Phaseolus mungo L.)

      A V Kumar S V Prasad K N Rao G R Rao

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      Gibberellin-like substances of black gram at different periods after soaking were extracted from seed and leachates into neutral, acidic and bound fractions. Five different factors in the acidic, four factors in the neutral and eight factors in bound fractions have been located based on their biological activity in the seed and their leachates. The effect of leaching of gibberellin-like substances at different intervals is correlated with the growth of performance of the seedlings at the end of each soaking period.

    • Cucurbitacins in relation to somatic embryonyin vitro

      Akhilesh Tewari N S Rangaswamy

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      Effects of four cucurbitacins, which occur mostly in seeds of Cucurbitaceae, and of cucurbitaceous tissue extracts on somatic embryony in tissue cultures of carrot,Citrus microcarpa andRanunculus sceleratus are described. Thin layer chromatographic analyses showed that the nucellar extract and the integuments ofLuffa cylindrica contain cucurbitain B. Studies with the extracts on all the three tissue culture systems have corroborated the observed inhibitory effect of cucurbitacins on somatic embryony. The role of cucurbitacins in plant embryogeny, and in the control of zygotic or adventive embryony in crop species is discussed.

    • Structure, distribution and classification of plant trichomes in relation to taxonomy III. Papilionoideae

      P Leelavathi N Ramayya

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      A detailed structure, organographic distribution, classification and taxonomic significance of trichomes in 42 species in the subfamily Papilionoideae is presented. In all, 28 trichome types are recognised in the taxon, of which 9 are newly described. The trichome types fit into four categories in accordance with the classification by Ramayya (1975). Based on the distribution of trichome categories, the Papilionoideae seems more related to the subfamily Mimosoideae than to the Caesalpinioideae. A key is provided for the identification of the species, based on the foliar trichomes.

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