Volume 81, Issue 3
March 1975, pages 101-144
pp 101-110 March 1975
The anatomy of the mature embryo and 34-day old seedling ofPicea smithiana (Wall) Boiss. has been described. The organization of the shoot and root apices in both is similar. The shoot apex shows five cytohistological zones, where the entire surface layer shows periclinal divisions and a small subapical initials zone. In the radicular and root apices there is a common initiating zone for the stele and columella in the centre surrounded by another common initiating zone for the cortex and peripheral region of the root cap. In the mature embryo thekappe divisions of the protoderm resulting in the peripheral region of the cap can be noted, which, however, disappear in the root of the seedling. The 34-day old seedling shows a root-hypocotyl-cotyledon vasculature without any connection with the shoot, where no vasculature has yet developed.
pp 111-117 March 1975
Epidermal morphology ofJasminum pubescence Willd.,J. arborescence Roxb.,J. malabaricum Wight,J. grandiflorum L., andJ. mesnyi Hance is described.
pp 118-126 March 1975
The cytological effects of penicillin and streptomycin have been studied on the meiotic cells of the grasshopper,Poecilocerus pictus. The interesting observations included a reduction in the Meiotic Index (Me.I.) at various concentrations and different durations, the occurrence of stickiness, breakage, fragmentation, lagging and groupings of the chromosomes and translocations. These results have been discussed and representative photomicrographs are provided. Some of these effects indicate the possible hazardous nature of the antibiotics on the genetic system.
pp 127-130 March 1975
Different varieties of bananas,viz., Basrai, Harichal, Lalkel (variety ofMusa cavendishii), and Rajeli, Safed Velchi (variety ofMusa paradisiaca) were studied for pectin-methyl-esterase (PME) activity at various stages of ripening. The highest activity was found at colour stage 4 (skin colour turning yellow). There was a continuous increase in PME activity of fraction III whereas fraction I and II reached a maximum after colour stage 4. PME activity of fraction I varied from 9 to 62 units × 102, fraction II 4 to 31 units × 102 and fraction III 5 to 49 units × 102 respectively. The activity was highest at colour stage 4 and then fell sharply in the advanced ripening stages.
pp 131-144 March 1975
Karyotype and meiosis were studied in several clones ofSaccharum spontaneum with chromosome numbers 2n=40 to 2n=126. Differences in the karyotype was observed between different clones with the same chromosome number. Karyotype symmetry/asymmetry has been indicated. The number of chromosomes in different cells of the same plant varied in many clones at meiosis and first pollen grain mitosis. Occurrence of B chromosomes in pollen mother cells and pollen grains were noticed in a few clones. At meiosis univalents, heteromorphic bivalents, secondary association of bivalents, etc., were noticed and their importance discussed.