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TIME COURSE OF ION ACCUMULATION AND ITS RELATIONSHIP WITH THE SALT TOLERANCE OF TWO GENETICALLY DIVERSE LINES OF CANOLA (BRASSICA NAPUS L.)

M. QASIM AND M. ASHRAF*

Abstract: A greenhouse experiment was conducted to examine the time course of ion accumulation in two genetically diverse lines of canola (Brassica napus) viz., Dunkeld (salt tolerant) and Cyclon (salt sensitive) subjected to 2.4 (control), 4, 8, and 12 dS m^-1 of NaCl. Plants were harvested every 10-day interval after the initiation of salt treatment and harvesting continued until 5^th harvest i.e., 50 days after the initiation of salt treatment. An age-dependent accumulation of Na⁺ and Cl- occurred in both lines and the discrimination in the two lines with respect to ion accumulation was discernable at the last three harvests, Dunkeld was significantly lower in shoot Na⁺ and Cl^- as compared to Cyclon. The salt tolerant line Dunkeld maintained higher K⁺/Na⁺ and Ca²⁺/Na⁺ ratios than those of the salt sensitive line Cyclon under saline conditions. However, the discrimination between the two canola lines with respect to K⁺/Na⁺ ratio was discernable at the later growth stages, whereas that of Ca²⁺/Na⁺ ratio at all stages. Discrimination between the two genetically diverse lines of canola with respect to accumulation of toxic ions was only possible at the later stages of vegetative growth rather than at the early stages.
 

Department of Botany, University of Agriculture, Faisalabad 38040, Pakistan.
Corresponding Author: email: ashrafm@fsd.paknet.com.pk