Modulation of growth,photosynthetic capacity and water relations in salt stressed wheat plants by exogenously applied 24-epibrassinolide |
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Authors: | Qasim Ali Habib-ur-Rehman Athar M Ashraf |
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Institution: | (1) Department of Botany, University of Agriculture, Faisalabad, 38040, Pakistan;(2) Department of Botany, Institute of Pure and Applied Biology, Bahauddin Zakariya University, Multan, 60800, Pakistan |
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Abstract: | Brassinosteroids promote the growth of plants and are effective in alleviating adverse effects of abiotic stresses such as
salinity and drought. Under saline conditions, improvement in grain yield is more important than simple growth. Previously
it was found that although foliar application of brassinosteroids improved growth of wheat plants, it did not increase grain
yield. In present study, influence of root applied 24-epibrassinolide was assessed in improving growth and yield of two wheat
cultivars. Plants of a salt tolerant (S-24) and a moderately salt sensitive (MH-97) were grown at 0 or 120 mM NaCl in continuously
aerated Hoagland’s nutrient solution. Different concentrations of 24-epibrassinolide (0, 0.052, 0.104, 0.156 μM) were also
maintained in the solution culture. Exogenous application of 24-epibrassinolide counteracted the salt stress-induced growth
and grain yield inhibition of both wheat cultivars. Of the varying 24-epibrassinolide concentrations used, the most effective
concentrations for promoting growth were 0.104 and 0.052 μM under normal and saline conditions, respectively. However, root
applied 0.052 μM 24-epibrassinolide enhanced the total grain yield and 100 grain weight of salt stressed plants of both cultivars
and suggested that total grain yield was mainly increased by increase in grain size which might have been due to 24-epibrassinolide
induced increase in translocation of more photoassimilates towards grain. Growth improvement in both cultivars due to root
applied 24-epibrassinolide was found to be associated with improved photosynthetic capacity. Changes in photosynthetic rate
due to 24-epibrassinolide application were found to be associated with non-stomatal limitations, other than photochemical
efficiency of PSII and photosynthetic pigments. Leaf turgor potential found not to be involved in growth promotion. |
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Keywords: | Brassinosteroid Growth Gas exchange Photochemical efficiency Triticum aestivum |
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