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ROLE OF MERCURY AND EXOGENOUS IAA ON XYLEM VESSELS AND SIEVE ELEMENTS IN CUCUMIS SATIVUS L.

NAJMA YAQUB CHAUDHRY¹* AND AISHA SALEEM KHAN

Abstract: High concentration of Hg i.e., 50 ppm and 100 ppm HgCl₂ was used to find the deleterious effects in internode of Cucumis sativus L. Xylem vessels and sieve tube members showed inhibition with mercury in both transverse and longitudinal planes. All data was compared with control plants grown under same conditions. When Hg was applied with IAA, there was less inhibition in growth as compared to plants treated with Hg alone, revealing the dominant role of IAA. Therefore, IAA can be beneficial in reducing the inhibition caused by mercury stress. The arrangement of vascular tissues within the bundle is bicollateral and hence the development of phloem region on both sides was studied. Xylem vessels and phloem cells showed more inhibition with Hg in large inner vascular cylinder (IVC) as compared with cells in smaller outer vascular cylinder (OVC).
 

Punjab University, Botany Department, Lahore, Pakistan. ¹ Tel: 042-5889564, ²Tel: 042-7514264
Correspondence E-mail: dr.najmayaqoob@hotmail.com, aishasaleemkhan@hotmail.com