Efficacy of exogenous glycine betaine application on sorghum plants grown under salinity stress
2004
Ibrahim, A. H.
A pot experiment was conducted to evaluate the beneficial effect of glycine betaine application on salinity tolerance of sorghum plants subjected to two salinity levels (125 and 250 mM) for 18 days. Salinity greatly reduced sorghum growth and this effect was more pronounced at 250 mM than at 125 mM NaCl. Foliar application of glycine betaine at 75 mM mitigated to some extent the adverse effects of salinity on sorghum growth. The measured osmotic pressure and solutes concentration (Na, K, Ca, Mg, QACs, total soluble sugar and betaine) increased while K/Na ratio decreased in sorghum sap with increasing salinity level. The major contributors to the measured osmotic pressure were found to be soluble sugars and K, however, this effect decreased with increasing salinity level while that of Na, proline and betaine increased. The obtained results clearly showed that betaine application reduced proline accumulation in sorghum sap under salinity treatments. It was appeared that the expanding leaf had more osmolality, K, sugars, proline and betaine concentrations than the fully expanded leaf. Conversely, Na, Ca and Mg concentrations were higher in the fully expanded leaf than the expanding leaf. Total N concentration increased, while that of C decreased with increasing salinity level. Hydrogen concentration slightly affected by salinity treatments. Stomatal conductance was markedly reduced with increasing salinity level; the main effect of foliar application of glycine betaine was not significant for this criterion.
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