Allelopathic Effects of Wheat Plant Roots (Intisar) Treated with Gibberellin under Different Age on Germination ,Seedling Growth of two Wheat Cultivars (Abu-Graib 3, Mexipack) Triticum aestivum L.

Laboratory, Greenhouse experiments were conducted to study the root aqueous extract effect of wheat (Intisar) that the shoot system of wheat was treated with four concentrations of Gibberellic acid (0,1,5,10) mg/L under three growth stages (20,40,60) days. The effect of soil previously was swon with the wheat (Intisar) with the same treatment on germination and seedling growth of two wheat cultivars (Abu-Graib 3,Mexipack).The results showed that the cultivar Mexipack was better than Abu-Graib 3 in the most characters studied (germination percentage, length and dry weight of coleoptile and radical) ,also the results indicated that the Gibberellin caused a significant increase in the most of the characters when compared with the control such as (germination, length, seedling-leaf area, longest root length). On the other hand aqueous extract of roots and soil previously sown caused inhibition germination and seedling growth of two wheat cultivars but the inhibition percentage decrease with increasing plant age.