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Title of Thesis

Ali Zafar Jafri
Institute/University/Department Details
University of Karachi/ Department of Botany
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
salt tolerance, cotton, b557, niab78, sarmast, qalandari, rohi

Effects of four levels of soil salinities (viz. 0.25, 0.5, 0.75 and 1.0% by weight on growth and development of different cotton cultivars were investigated. These studies were started with sixteen cotton cultivars at germination stage, out of which five cultivars (viz. B557, Niab78, Sarmast, Qalandari and Rohi) which showed better performance, were selected for further work. A delay in the duration of germination, proportional to the increasing salinity levels, was observed in all the cotton cultivars. Since emergence of seedlings was very poor at higher levels of salinities, ten days old seedlings raised on normal soil and hardened by saline water irrigation, were transplanted directly in the pots containing above mentioned levels of soil salinities

On the basis of their vegetative biomass production, these cultivars were graded as Rohi> Sarmast> Qalanderi> B557> Niab78 on the different levels of salinities. Lower rate of relative growth (RGR) during early period under salt stress prolonged the vegetative growth period as a result the reproductive growth was carried the plants to relatively colder season. This change of climate brought a decrease in pollen germination, inhibition in fertilization and reduction in yield. Germination of pollen grains in vitro also demonstrated adverse effects of low temperatures

Anatomical adaptations as effects by salinity stresses were seen in the form of increased mesophyll surface area and relatively large size of stomata, which could be helpful in maintaining exchange rate of CO2 under saline environment

Ionic distribution indicated greater transportation of Na+ to the aerial parts of the plants. They were still capable of maintaining this ratio above one even under higher salinity regimes

Reproductive potential of these cultivars was studied by recording monopodial and sympodial branchings, total fruiting points (squares), flowers and bolls in cotton plants under normal and saline conditions. If percent reduction in yield is taken as criteria of salt tolerance, these cultivars could be graded as B557> Nib78> Qalanderi> Sarmast> Rohi respectively. It was interesting to note that inspite of being susceptible to salinity, some cultivars due to growth vigour give such a good yield that the amount of their produce excelled than that of salt tolerant cultivars. On the basis of the tonnage, the comparative performance of the cultivars under study was as Qalandari> Niab78> B557> Sarmast> Rohi even under the highest level of salinity. Keeping in mind the total produce at the soils of different salinity regimes one can select a cotton cultivar for his fields on the basis of this research work

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents 0
61.33 KB
2 1 Introduction 7
101.84 KB
3 2 Material And Methods 13
81.45 KB
4 3 Observations And Results 23
1204.43 KB
  3.1 Vegetative Growth 23
  3.2 Reproductive Growth 65
  3.3 Analytical Studies 78
5 4 Discussion 116
425.32 KB
  4.1 Conclusions 144
  4.2 Literature Cited 146
  4.3 Acknowledgement 165