| Pak. J. Bot., 38(4): 1127-1136, 2006. | Back to Contents | ||||
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Updated: 09-07-09 | ||||
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EFFECT OF SALICYLIC ACID APPLIED THROUGH ROOTING MEDIUM ON DROUGHT TOLERANCE OF WHEAT MUHAMMAD WASEEM, HABIB-UR-REHMAN ATHAR** AND MUHAMMAD ASHRAF*
Abstract: An experiment was conducted to assess whether exogenously applied SA
through the rooting medium could mitigate the adverse effects of water
stress on plant growth, photosynthesis and nutrient status of two wheat
genotypes. For this purpose, salicylic acid @ 0, 5, and 10 mg L-1
was applied through the rooting medium to plants of two wheat lines
growing in plastic beakers (250 mL) filled with Hoagland's nutrient
solution containing 0 or 19% PEG8000 to represent two water
regimes of control (0 MPa) and -0.6 MPa respectively. Different levels
of SA applied through the rooting medium increased photosynthetic rate
in both cultivars under non-stress conditions but only in S-24 under
water stress conditions. Exogenous application of 5 or 10 mg L-1SA
caused an increase in stomatal conductance, transpiration rate, and
sub-stomatal of water stressed plants of cv. S-24 whereas it was true
for droughted plants of MH-97 only when 5 mg L-1 SA applied. Cultivar
S-24 was generally higher in N and P contents of shoot and root than
that in genotype MH-97 under both normal and water stress conditions.
A decrease in shoot and root N contents of both genotypes and shoot
and root P contents of genotype S-24 only was observed in stressed plants
when 5 mg L-1 of SA was applied through the rooting medium,
whereas the same was true for root P and shoot Ca2+ contents
in the non-stressed plants of both cultivars. Application of salicylic
acid through the rooting medium significantly reduced the root K+
of two cultivars under both normal and water deficit conditions. Although,
exogenously applied SA through the rooting medium had growth promoting
effects under non-stress conditions, it did not mitigate the adverse
effects of drought stress on growth of both cultivars, though genotype
MH-97 showed some recovery under water stress conditions. Department of Botany, University of Agriculture, Faisalabad 38040,
Pakistan. |
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