I= A STUDY OF MORPHO-PHYSIOLOGICAL EFFECTS OF GAMMA IRRADIATION ON SHOOT APLCAL MERISTEM AND TISSUE DIFFERENTIATION IN STEM AND LEAF OF CAPSICUM ANNUM L.
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Title of Thesis
A STUDY OF MORPHO-PHYSIOLOGICAL EFFECTS OF GAMMA IRRADIATION ON SHOOT APLCAL MERISTEM AND TISSUE DIFFERENTIATION IN STEM AND LEAF OF CAPSICUM ANNUM L.

Author(s)
Javed Iqbal
Institute/University/Department Details
University Of The Punjab
Session
1968
Subject
Botany
Number of Pages
235
Keywords (Extracted from title, table of contents and abstract of thesis)
gamma irradiation, capsicum annum, gamma rays, internal morphology, shoot apical meristem, external morphology

Abstract
Seedlings of capsicum annum were irradiated at cotyledonary, 4‚€”leaf , 8‚€”and 12‚€”leaf stages of development with gamma-rays (co60) at doses of 1 kr, 2kr, 3kr, 4kr, 5kr, 7.5 kr and 10 kr. Effects of irradiation were studied both on external and internal morphology of the seedlings

External morphology. One of the most characteristic stem Reponses is death of the shoot apex at 3 kr-10 kr doses. Growth in length remains retarded due to the failure of internodes to elongate. Fascination of stems is also very common. In leaves dwarfing, thickening, margin and petiole curling and mottling are common anomalies. Flowering and fruiting is reduced and changes also occur in the form of the fruit.

Internal morphology. The central region of the shoot apex and tunica 1 are most radiosensitive and on account of this outline of the shoot apex is changed. Periclinal divisions in central most cells of tunica 1 and 11 are occasionally observed. Mitotic intensity is greatly reduced. Abnormal isolated vessels are found in some of the shoot apices irradiated at higher doses. Recovery is either by direct healing or by the formation of new ‚€œgrowth centres‚€Ě, or there is a formation of a substitute meristem. No healing takes place at higher doses of 5 kr-10 kr. Rate of respiration decreases at all doses. Similarly nucleic acid content shows a linear decrease except at 1kr doses where a slight increase is noticed.

Tissue differentiation is also markedly affected. First procambium, phloem and xylem are initiation earlier than in the control. Similarly the initiation of metaphase and met xylem takes place earlier ( in terms of distance form the apex). The number of sieve elements and vessel elements in the foliage leaves and stem show a pronounced increase with the increasing dose and time after irradiation. At higher doses, however, the initiation of new leaves is completely suppressed.

Present study reveals that the percentage of cell death at different doses and at different stages of development is one of the most important immediate causes underlying the changes in morphology resulting from irradiation. There are also reasons to believe that important biochemical and physical changes must precede the cell death. Changes in synthesis of nucleic acid resulting form radiations become more meaningful when viewed in terms of cell number. These results are discussed in relation to the precious information available in this field.

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9115.92 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
348.37 KB
2 1 Introduction 1
184.49 KB
3 2 Materials And Methods 5
119.45 KB
  2.1 Effects Of Gamma Rays On Shoot Apical Meristem 7
4 3 Method Of Study 8
477.39 KB
  3.1 External Morphology 8
  3.2 Internal Morphology 9
5 4 Literature Survey 16
782.44 KB
6 5 Results 29
3841.04 KB
  5.1 External Morphology 29
  5.2 Internal Morphology 40
7 6 Discussion 115
1497.67 KB
  6.1 External Morphology 116
  6.2 Internal Morphology 122
8 7 Method Of Study 154
135.4 KB
  7.1 Stem 154
  7.2 Leaf 156
9 8 Literature Survey 158
367.37 KB
10 9 Results 167
693.18 KB
  9.1 Stem 167
  9.2 Leaf 181
11 10 Discussion 190
60.07 KB
12 11 Summary 192
135.35 KB
13 12 Acknowledgement 198
23.88 KB
14 13 Literature Cited 199
699.01 KB
15 14 Plates 215
20.18 KB