• Volume 98, Issue 6

      December 1988,   pages  425-522

    • Plant tissue culture: Perceptions and realities

      Abraham D Krikorian

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      There is a perception that phenomenal progress has been made in so-called tissue culture technologies as they apply to non-woody plants. Moreover, many also seem to think that while temperate woody species have yielded toin vitro manipulation, tropical and subtropical ones have generally remained recalcitrant. An attempt has been made to place all this in context, and to allow for emergence of a realistic conclusion of where we really seem to be. Much progress has been made but plant tissue culture procedures still have a long way to go before they can collectively qualify, by the most rigid criteria, as a routine tool. If a technology is, in fact, a means to amplify our ability to do something in a relatively, if not virtually, risk-free manner, anyone who has done much serious plant tissue culture will know that in most cases it does not yet meet the criterion. When we can predictably control things—with maximal certainty, risk-free, or at least with minimal or acceptable risk, we will have a biotechnology. It sounds very modern to use the word ‘biotechnology’ but one does not achieve the status of a biotechnology merely by many or most agreeing to use the term. My belief is that we work against ourselves by doing so. Basic scientific inquiry is stifled. We still need to provide an appropriate framework and vehicle for basic investigations that will enable many important unanswered questions to be addressed. From a practical perspective these include: Why does progress seem to be slow in woody plants—especially in the case of tropical and subtropical species; what are some of the constraints imposed on the systems being worked with; how much of a gap is there between knowledge at the research level and application; how can one accelerate activities to improve both our perspective and still make positive basic and practical contributions to this area? A major problem has been that some systems are quite for along in their development; others are in their infancy. It is hoped that supporters of plant tissue culture efforts will not abandon basic research programs in favor of applied initiatives just because some species seem to be more difficult to work with initially than others and hence will require much more time at the basic research level, and well before one can begin to develop and ultimately exploit. Basic botanical and plant cell biology research must be fostered. Those dedicated to studying plant biology from anin vitro perspective have a greater role now than ever to play. Responsible action is crucial. Resistance must be given to those who prematurely insist that integration into practical schemes should predominate our thinking and setting of priorities. At the same time there is a delicate path that must be taken so that opportunities for learning and making basic contributions are not missed. Plant scientists clearly have a challenge to meet. Decision making must take into account the state of the science from the scientists’ perspective—not merely an administrative perspective.

    • Oedogoniales of Uttar Pradesh, India—Oedogonium Link

      H M Shukla G L Tiwari U C Pandey Iqbal Habib

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      Seven species ofOedogonium Link collected from Mauri lake, Pratapgarh, Uttar Pradesh during July 1984 to August 1986. Of theseOedogonium boscii (Wittr.) Hirn var.minor var. nov. is new for Phycology; two species viz.Oedogonium grande (Kuetz.) Hirn andOedogonium praelongum Hall.ex And. are first records for India and the remaining 4 species viz.Oedogonium mexicanum (Wittr.) Hirn,Oedogonium exocostatum Tiffany var.jodhpurense Goyal,Oedogonium costatosporum Jao var.longisporum Gonzalveset Sonnad andOedogonium epiphyticum (Trans.et Tiffany) Tiffany are new records for northern part of India.

    • Leaf architecture in Tamaricaceae

      A K Gupta Y S Murty

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      The leaf architectural pattern in 6 species ofTamarix and two species ofMyricaria has been investigated. The leaves are simple, alternate and sessile. InTamarix aphylla, Tamarix dioica, Tamarix gracilis andTamarix troupii the leaves are completely or partially sheathing. In these species only the primary vein is distinguishable, the secondaries and the further orders of venation being not distinguishable from one another. In the other two species ofTamarix and inMyricaria the major venation pattern is pinnatecamptodromous type. The intercostal venation is of random reticulate type, and the marginal ultimate venation is incomplete. The areoles are polygonal to irregular in outline and randomly oriented. They may contain one or more veinlets or none. There is no direct correlation between the size of an areole and the number of vein endings. Hence, these characters cannot be said to be taxonomically significant as far as the species ofTamarix andMyricaria are concerned.

    • Properties of phosphatases from green algaScenedesmus incrassatulus Bahlin and blue-green algaSynechococcus aeruginosus Nag.

      T R K Reddy R Lakshminarayana

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      Studies on phosphatases (acid and alkaline) inSynechococcus aeruginosus, a prokaryotic blue-green alga, andScenedesmus incrassatulus, an eukaryotic green alga under different conditions revealed that the acid phosphatase exhibited maximum activity to pH 4·7 and 37°C in both the algae while alkaline phosphatase displayed greatest activity at 37·5°C and 10 pH inSynechococcus aeruginosus and at 10·6 pH and 37·5°C inScenedesmus incrassatulus. TheKm values were found to be 50 and 17 mM for acid phosphatase and 4·2 and 8·3 mM for alkaline phosphatase in blue-green and green algae respectively. The inhibitory effect of metal ions (Cu2+, Fe2+, Hg2+, Zn2+) on acid phosphatase activity is similar in both the algae whereas on alkaline phosphatase, their influence varies. Sodium fluoride and EDTA inhibited both the phosphatases activity with the increased concentrations in both the algae. Benzene hexachloride (50%) retarded these enzyme’s activities at higher concentrations in these algae.

    • N2-fixation (N2-ase activity) inAzospirillum strains

      V M Rao Jayshree Banwari Lal P Shailaja H S Narayana

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      The nitrogenase activity (N2-fixation) ofAzospirillum isolated from the root region of C4Digitaria, Chloris, Cynodon, Dichanthium, Lasiurus andCenchrus growing in different tracts of Rajasthan, was studied in spot batch cultures on sodium malate medium both under air and 1% oxygen at regular intervals of 24 h for a span of 7 days. The morphological and cultural characteristics ofAzospirillum strains belonging tolipoferum andbrasilense group (both nir+ and nir) have also been studied. The strains oflipoferum group performed better and exhibited more N2-ase activity on agar surface under 1% O2 and associated with the roots compared to the strains ofbrasilense group.

    • Response to radiation andin vitro growth of two species ofLuzula with non-localised centromere

      Jayanti Sengupta A K Sharma

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      In vitro growth preceded by gamma-radiation was studied in two species with non-localised centromere, namelyLuzula elegans andLuzula pediformis. Seed germination was affected by radiation doses. Cytological investigation revealed dose dependent chromosomal aberration and spindle disturbances. Chromosome break and fragments were present inLuzula elegans but absent inLuzula pediformis. The growth of the callus was affected at higher doses in both the species. The radiosensitivity of the two species ofLuzula with diffuse centromere has been discussed.

    • Transformation of the grain legumeVigna aconitifolia Jacq Marechal byAgrobacterium tumefaciens, regeneration of shoots

      Ravinder Gill S Eapen P S Rao

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      Hypocotyl, stem, leaf and shoot-apex of one-week-old seedlings ofVigna aconitifolia were inoculated with the nopaline wild type (T37) ofAgrobacterium tumefaciens to induce tumours. Hypocotyl segments of 1 cm length fromin vitro grown plants were also co-cultivated with a bacterial suspension to obtain transformed tissue. Axenic cultures obtained from both the experiments when cultured on basal medium proliferated into callus which differentiated into shoot buds on the same medium after, repeated subcultures. The transformed nature of the shoots was confirmed by their failure to produce roots, growth on hormone-free medium and the presence of nopaline and nopaline dehydrogenase.

    • Wind-tunnel estimation of fungi colonizing sorghum seed from field to storage

      P Shankara A Ramalingam

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      Microbial loads of sorghum seeds were estimated using a wind tunnel at 3 successive stages; mid ripe, threshing and storage. Very high concentration of field fungi viz.,Curvularia, Drechslera, Fusarium, Phoma andSphacelotheca sorghi were recorded from seeds at threshing stage, whereas their populations decreased during storage. Storage fungi such asPenicillium andAspergillus increased considerably after storage. High concentration of microbes were released even with least agitation.

    • Growth and foliar variation among provenances ofEucalyptus camaldulensis Dehn. grown at Dehradun

      R K Vakshasya

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      Results of provenance trial ofEucalyptus camaldulensis, established at New Forest, Dehradun, are discussed. Highly significant differences were observed among the provenances for growth (P=0·001) and foliar (P=0·01) characteristics. The provenances of Katherine, NT (S3); Hughendon, Queensland (S7) and Petford, Queensland (S1) from Australia proved best at the site of introduction with mean height 12·97, 13·63 and 12·69 m and mean diameter 10·39, 9·47 and 8·49 cm respectively. Selection of provenances has been advocated on the basis of their comparative performance and within provenance variability. Overall performance of northern and southern populations, having a line of discrimination somewhere between 21°S and 23°S latitude, has been discussed. For the first time statistically significant provenance difference has been explored at stomatal level. Significant negative correlations were obtained between provenance latitude and height (r=−0·64), diameter (r=−0·73) and stomata length (r=0·84). The impact of maximum temperature of the provenance on height and leaf length was observed to be positive and significant (r=0·824 and 0·710 respectively).

    • Seasonal nutrient status of Banjara lake, Hyderabad

      G Narender Reddy M N V Prasad

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      Seasonal and diel variations of nutrients viz. nitrate, nitrite, ammonia, soluble reactive phosphorus and silica in Banjara lake (identified by Andhra Pradesh Fisheries Department for pisciculture) during August 1986 to July 1987 were reported. Nitrate, nitrite and ammonia reached highest concentrations in March (3·76±1·74 mg l−1), July (575±77 μg l−1) and April (404·6±127 μg l−1) respectively. However, fish kills through nitrite toxicity was not observed at the reported nitrite concentrations. Ammonia decreased during summer mainly due to utilization by phytoplankton blooms. The highest value of soluble reactive phosphorus was observed in April (956±44 μg l) attributed to sewage, domestic effluents and also release from sediments. Silica was at a maximum in October and decreased during diatom blooms in December. Clear pattern of diel variation was not observed for nitrate, nitrite and phosphorus. However, ammonia showed diel variation having higher concentrations at 6 h than 12, 18 and 24h due to its slower uptake by phytoplankton during nights. Chlorophylla was at a maximum in May (32 mg m−3) at N/P ratio of 5·3 with the dominance of cyanophyceae and chlorophyceae.

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