• Volume 100, Issue 2

      April 1990,   pages  85-152

    • A new species ofJubula Dumort. from Milam in Kumaon (western Himalaya)

      S C Srivastava Deepak Sharma

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      A new species ofJubula Dum.,Jubula himalayensis sp. nov. has been described from the western Himalaya (on way to Milam glacier). The species is characterized by plants having monoecious sexuality, entire bracts and bracteoles, oval to spherical, homogenous and refracting 4–7 oil bodies per cell.

    • Cytology of hardwoods

      Y S Bedi

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      Cytology of 51 woody species including 7 commercial timbers, belonging to Gamopetalae and Monochlamydeae have been carried out. Two genera (Melodinus monogynous, n=11 andHomonoia riparia, n=22) and 8 species (Gardenia latifolia, n=11;Ixora barbata, n=11;Ligustrum sinense, 2n=46;Strophanthus wallichii, n=11;Dolichandrone cynanchoides, n=20;Beilschmiedia roxburghiana, n=12;Persea gratissima, n=12 andPhyllanthus discoides, n=13) have been counted for the first time. Variable chromosomes have been recorded for 7 species. In addition phenomena of cytological interest like structural hybridity due to reciprocal translocations (Rauvolfia serpentina, 2n=22 andBroussonetia papyrifera, 2n=26), B-chromosomes (Breynia rhamnoides, n=26+0−2B andJoannesia princeps, n=11+0−2B) and cytomixis (Serissa foetida, 2n=22) have been detected. Abnormal microsporogenesis in a diploid tree ofCleistanthus collinus (n=10) might be attributed to the disfunction of spindle apparatus.

    • Effect of L-methionine sulphoximine on the enzymes of nitrogen metabolism in barley leaves

      P A Kumar Y P Abrol

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      L-methionine sulphoximine, a potent inhibitor of glutamine synthetase decreased nitrate reductase activity by 50% at the end of 12h of treatment while nitrite reductase was insignificantly affected. By 3 h the inhibition of glutamine synthetase activity was complete. Elevated levels of ammonia induced by L-methionine sulphoximine did not influence glutamate dehydrogenase. It is inferred that ammonia accumulation does not affect photosynthetic electron transport which supplies reducing power to nitrite reductase. The failure of glutamate dehydrogenase activity to be induced by high ammonium levels shows that it is not involved in the process of ammonia assimilation in the leaves.

    • Stability of pollen sterility in cytoplasmic-genetic male sterile lines in rice

      S B Pradhan S N Ratho P J Jachuck

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      On the basis of the shape and staining pattern of pollen grains, 22 cytoplasmicgenetic male sterile lines of 5 different cytosterility systems in rice could be classified into 4 categories, viz., unstained withered sterile, unstained spherical sterile, stained round sterile and stained round fertile. Using this system, the cytoplasmic-genetic male sterile lines were classified into 5 groups, characterised by relative frequency of the different classes of pollen grains.

      These cytoplasmic-genetic male sterile lines were grown during 6 seasons (1984 and 1985 wet, 1986 and 1987 dry and wet) to study the stability of pollen sterility. Six cytoplasmicgenetic male sterile liens (V 20 A, Zhenshan 97 A, IR 54753 A, IR 54754 A, IR 54757 A and IR 54758 A) having wild abortive type cytoplasm were found to be stable for pollen sterility.

    • Changes in the phenolic contents of rice cultivars towards air pollution exposure

      M Anbazhagan R Krishnamurthy K A Bhagwat

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      Three cultivars of rice (Oryza sativa L.) were exposed to the polluted environment of a fertilizer plant to evluate the changes in the phenolic contents due to air pollution. Two soil N regimes under normal watering and water stressed (half-field capacity) conditions were imposed on 30-day old plants. Controls were maintained 10 km away from the factory in an unpolluted area using the same cultural practices. As the main effects, air pollution decreased the levels of phenolic content at 55 days and increased at 70 days. The cv. GR 3 appeared to accumulate high phenolic contents at the later stage while cv. CO 43 decreased the same. The cv. TKM 9 showed the similar pattern as that of cv. GR 3. The interaction of cultivar with nitrogen and cultivar with water produced no significant effect. It was concluded that the main effect of air pollution appeared to be the increased amount of phenolic contents towards growth and the accumulation was high only in tolerant cultivars.

    • Factors affecting germination ofPeronospora parasitica in radish

      P Jang K M Safeeulla

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      Oospores ofPeronospora parasitica are found to be dependent on environmental factors such as temperature, light, pH of the medium and age of oospores. Optimum temperature of 23°C is required for their germination. Drying and chilling had no marked effect on oospore germination. At pH 7·5, 42% germination was recorded while at pH 4·5 only 1% of oospores germinated. Oospore germination increased with increase in their age.

    • Production and viability ofPeronospora parasitica in radish

      P Jang K M Safeeulla

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      InPeronospora parasitica the inoculum load is found in the form of oospores in the leaf and seed tissues of radish. Out of 400 seeds tested, 10% showed the presence of oospores in the pericarp and 0·1% in the embryo. The 2,3,5-triphenyltetrazolium chloride test is a quick method of determining the viability of the oospores. Viability of oospores based on infection capacity after storage, though a long process, is effective and reliable. Results ofin vitro andin vivo experiments show that the oospores need natural weathering, under field conditions, for a period of one year for maximum infection in radish and those stored for two years under the same conditions, has an adverse effect on their infection capacity. Infection capacity was higher among oospores exposed to weathering than those retained in laboratory.

    • Raft cultivation ofGracilaria edulis (Gmel.) Silva

      K Subbaramaiah P C Thomas

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      The single-rope floating raft cultivation ofGracilaria edulis was tried at Krusadai Island for one year. In 3 harvests mean biomass annual yield of 4 kg (wet) m-1 was obtained which is the highest recorded for the alga. The raft cultivation of the alga at different levels has shown that maintaining the cultivation ropes at the top level will give better yield

    • Speculations on niches occupied by fungi in the sea with relation to bacteria

      S Raghukumar

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      The significance of fungi in the marine environment is poorly known when compared with the bacteria. Based on information available on bacteria and fungi in the sea and their structural characteristics, the various niches where the latter may play important roles is speculated upon in this article. Among the 3 niches discussed, the fungi, including thraustochytrids may be significant endobionts in substrates such as dead and living plants and calcareous shells. Substantial information is already available on fungi in decaying salt marsh grass and mangrove leaves, seedlings and wood and on parasites in macro- and microalgae. The need to investigate fungi as epibionts on surfaces of various organic and inorganic substrates and also sediments has been stressed. While bacteria are known to be significant as planktonic forms, thraustochytrids and yeasts in this and other niches have not been studied in detail.

    • Litter production and seasonality in tropical moist forest ecosystems of Uttara Kannada district, Karnataka

      D M Bhat

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      Microlitterfall, ground litter and large wood litterfall were quantified in differently managed forest ecosystems of Uttara Kannada district (lat. 13°55′ to 15°31′N; long. 74°9′ to 75°10′E) with an annual rainfall of 2500 mm largely restricted to 5 months from June–October. Total microlitter produced ranged from 5–10 t/ha/year, ground litter produced ranged from 12–21 t/ha/year and largewood litterfall values ranged from 0·15–1·24 t/ha/year. In all the forest sites leaflitter was found to be major component which constituted 65–92% of the total microlitterfall and 75–94% of the total groundlitter produced. There appeared to be little seasonality in the total microlitterfall in the forest sites with a greater diversity of species, but the seasonal variation was distinct in monoculture and few species dominated vegetation types. Microlitterfall and ground litter production were highest in the dry season and they were negatively correlated with mean monthly rainfall.

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