| Pak. J. Bot., 38(2): 341-351, 2006. | Back to Contents | ||||
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Updated: 09-07-09 | ||||
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INFLUENCE OF EXOGENOUSLY APPLIED GLYCINEBETAINE ON THE PHOTOSYNTHETIC CAPACITY OF TWO DIFFERENTLY ADAPTED WHEAT CULTIVARS UNDER SALT STRESS SYED HAMMAD RAZA, HABIB-UR-REHMAN ATHAR** AND M. ASHRAF*
Abstract:
Ameliorative effect of exogenously applied glycinebetaine (GB) on photosynthetic
capacity of two wheat cultivars differing in salt tolerance grown under
salt stress was assessed. Plants were grown under field conditions at
2.84, 15 dS/m in split-split plot design. Different levels of GB (no
spray NS, 0.1% Tween 20 solution, 50 and 100 mM GB in 0.1% Tween 20
solution) were exogenously applied as a foliar spray to salt tolerant
(S-24) and moderately salt sensitive (MH-97) wheat cultivars under saline
and non-saline conditions. Salt stress reduced the photosynthetic capacity
of both cultivars. Reduction in photosynthetic rate was primarily due
to stomatal limitations. Cultivar S-24 excelled MH-97 under salt stress
with respect to photosynthetic rate and leaf turgor potential. Salt-induced
reduction in photosynthetic capacity was ameliorated by exogenous application
of GB. High accumulation of GB mainly contributes to OA, which is one
of the factors for improving photosynthetic capacity under salt stress.
Better osmotic adjustment or plant water status due to GB application
increased the stomatal conductance and thus favored higher CO2 fixation
rate. The protective effect of GB on photosynthetic pigments and GB
induced reduction in transpiration rate are additional factors which
might have contributed to better growth of wheat cultivars under salt
stress. However, cv. S-24 was higher in photosynthetic capacity and
plant water status or osmotic adjustment than MH-97, which could explain
the ability of the salt tolerant S-24 to show higher salt tolerance
than the moderately sensitive MH-97.
Department of Botany, University of Agriculture, Faisalabad, Pakistan. |
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