• Volume 76, Issue 2

      August 1972,   pages  39-84

    • Germination regulating mechanism in arid-zone plants: High temperature stimulus and germination ofRhynchosia seeds

      P Mullick U N Chatterji

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      Constant high temperature pretreatment given to the seeds ofRhynchosia minima D.C. andRhynchosia arenaria Blatt. and Hall., beside breaking hard seedcoat dormancy, tends to stimulate germination as well as seedling growth.

      Favourable results as regards germination and seedling growth have been obtained by taking recourse to high temperature pretreatment in the range of 60° C. to 90°C. for periods of 12 to 24 hours; the seeds ofR. minima needed pretreatment at 90° C. for 12 hours, and the requirement forR. arenaria was observed to be 24 to 36 hours at the same temperature.

      Pretreatment at temperatures between 80°C. to 90°C. rendered the seeds capable of water absorption at somewhat higher rates than the untreated controls. It also led to an increase in dry weight of the seeds as a higher protein nitrogen value was recorded in the treated seeds as compared to that in controls.

    • Life-history ofCycas circinalis L - Part V. Seedling anatomy

      L N Rao

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      The paper deals with the germination of the seeds ofCycas circinalis L, the growth and structure of the different parts of the seedling in the stem, root, cotyledons and plumule. The anatomy of four different types of roots, is given. The anatomy of the stem, cotyledonary plate, procambial strands and their orientation in the stem and root are described. The origin and development of stomata found on the hypocotyledonary region of the embryo are given in detail. The cotyledons, their vasculature and final fate are described.

    • Feldspars from the granitic rocks of chipurupalle-razam area, srikakulam district, andhra pradesh

      R Dhana Raju J S R Krishna Rao

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      Potassium feldspars from the granitic rocks of Chipurupalle-Razam area of Srikakulam District, Andhra Pradesh were studied by optical, chemical and X-ray diffraction methods. Most of the potassium feldspars occur both as porphy roblasts and in the groundmass in both orthopyroxene-bearing and garnetiferous granitic rocks. Potassium feldspars of the opx bearing granitic rocks are more or less homogeneous, while those of the garnetiferous granitic rocks and pink granite are mostly perthitic. The perthites are classified as stringlets, strings, rods and beads, and it is suggested that the perthite formation was due to exsolution.

      Chemical analysis and X-ray study showed that some of the feldspars are ferriferous orthoclasses. Qualitative spectrographic analysis indicates that Ba, Sr, Cr, Ga, Cu, Pb and Mn are present, while other elements such as Rb, Li, V, Be, Co, Ni, Ag, Ge and Sn were not detected. X-ray diffraction studies have shown the microcline to be of intermediate type with Δ=0·59. The structural equivalents of the feldspars studied are P50–56F, SH 1070 and Spencer ‘U’ of Wright and Stewart (1968). It is claimed that ferriferous orthoclase represents high temperature and pressure form, while intermediate microcline represents low temperature and pressure form in this series. Twin law studies on plagioclase feldspars indicated a metamorphic origin for the granitic rocks in the area.

    • Foetal membranes and placentation in the Indian leaf-nosed bat,Hipposideros fulvus fulvus (Gray)

      K B Karim

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      1.Hipposideros fulvus fulvus breeds once a year in a restricted season. The uterus is bicornuate and is morphologically symmetrical. However, the left side shows a slight physiological dominance over the right side. During each cycle a single young is produced.

      2. The foetal membranes at advanced pragnancy are described.

      3. The amnion is a thin bilaminar membrane closely adhering to the body of the foetus.

      4. The yolk-sac splanchnopleure lies as a collapsed bag near the placental disc. Both endodermal and mesodermal elements undergo hypertrophy.

      5. The chorio-allantoic placenta is mesometrial. A deep cleft in the centre of the placental disc separates it into two moieties. The placenta is labyrinthine and vasodichorial.

    • Studies on cotton stenosis—I. Auxin metabolism of the diseased plant

      P Narayanasamy T Jaganathan K Ranganathan A Palaniswami

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      Cotton plants infected by stenosis disease show growth abnormalities which may possibly be due to an abnormal reduction in the IAA-contents of the diseased plants. The accelerated activity of peroxidase might be responsible for the oxidation of IAA. The activity of IAA-oxidase was reduced in infected plants. This may be due to the higher concentrations of phenolics induced by higher activity of polyphenolase.

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