Metallic mercury is considered as an extremely toxic, persistent, non essential as well as non-biodegradable metal that experience several changes during transfer through various trophic levels of the food chain1.
Heavy metals can lead towards irreparable damage of important metabolic constituents and vital bio molecules. Moreover, they are also known to cause permanent injury to the plants cell membrane, particularly vascular bundles2.
Additionally, they also act as growth inhibitors by restraining the proper development of plant. In their presence, the number of open stomata gets decreased and ultimately causes deficiency of oxygen in plants3. It is also reported that heavy metals produce anatomical modifications in primary leaves therefore, treatment induced changes in the shape of pallisade cells4.
Furthermore, heavy metals affect the plant badly as they are also found to lessen almost all growth parameters5 as well as disturbance in the metabolic processes of living organism6. Accordingly, cadmium and mercury were also noticed for bringing out severe effects at elevated concentration and longer duration regarding seedling growth as well as metabolism7.
This situation urged scientists in order to study the effect of mercury (Hg) on germination and histomorphology of the hypocotyls of Cymopsis tetragonoloba (guar or cluster bean). For this purpose, scientists collected the data after fifteen days and then compared with control8.
During this experiment, mercury was found to inhibit the growth parameters of tested plant. Moreover, tissue structure of hypocotyls also got altered. It was also noticed that mercury decrease the area of stem as well as leaves. In addition, Transverse Section (T.S.) of treated hypocotyl with amplified amount of Hg showed abridged cell size in comparison with control. Development of xylem also affected, straight T-shaped tissues were formed and phloem was of small patch in cortical region.
Conclusively, accumulation of mercury influence the structure of the cell and damage the root system because of which transportation of water from the roots to the tips of new leaves also gets decreased that ultimately leads towards drastic effect on germination, growth and development of the plant.
Key words: metallic mercury, non-biodegradable metal, irreversible injury, vascular bundles, growth inhibitors, germination, hypocotyls, Cymopsis tetragonoloba
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- Stoyanova, D., 1998. Effects off acid rain on the anatomy of the leaves of Phaseolus vulgaries L. Biol. Plant, 40: 587-588.
- Dalal, T. and P. Baiyain, 1985. Effect of mercury, arsenic and lead on germination and seedlings growth of two jute varieties. Environ. Ecol., 3: 403-407.
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- Rafia Azmat, Shabana Askari and Saba Haider , 2006. Effect of Toxic Metal Mercury on Histomorphology of Cymopsis tetragonoloba. Asian Journal of Cell Biology, 1: 34-39.