Effect of seawater salinity and gibberellic acid on abscisic acid, amino acids and water-use efficiency by wheat plants

A pot experiment was carried out to investigate the effect of presoaking wh eat grains (Triticum aestivum L.) in gibberellic acid at 50 mM on cumulativ e leaf area, relative water content and abscisic acid level in developing l eaves as well as on amino acids in harvested grains and on the water-use ef ficiency of wheat plants irrigated with 10 or 25% seawater. At various stag es of leaf development, irrigation of wheat plants by seawater at 10 or 25% generally decreased cumulative leaf area, relative water content and water -use efficiency (WUE) in grain (WUEG) and biomass (WUEB), and at the same t ime induced accumulation of free and bound-ABA and amino acid content in ha rvested grains. In the majority of cases presoaking grain in GA(3) alleviat ed the inhibition of the cumulative leaf area, improved water status of lea ves by increasing their relative water content and, at the same time, reduc ed the accumulated free-ABA in developing leaves as well as the amino acids in harvested grains of seawater-treated plants. Furthermore, grain pretrea tment with GA(3) induced a dramatic increase in proline relative to total a mino acids.