Tolerance of bio-fertilized Delonix regia seedlings to irrigation intervals

This work aims to investigate the effect of different bio-fertilizers (Arbascular mycorrhizae fungi, Azotobacter chroorcoccum, yeast strains and mixture of all inoculum) and irrigation intervals (3, 6 or 12 days) on the growth and chemical composition of Delonix regia seedlings grown in sandy soil. Pot experiments were conducted using a randomized complete blocks design with three replicates during two successive seasons of 2013 and 2014. The results indicated that dual bio-fertilizers led to significant increase in growth characters  (plant height, root length, number of branches/plant, total fresh and dry weights/plant), microbial populations and AM fungi colonization (%), enzymatic activities, chemical composition (plant pigments, total carbohydrates, proline content, N, P, K) besides antioxidant enzymes such as catalase (CAT),and peroxidase (POD) compared to the un-inoculated seedlings (as control) at the recommended dose of NPK chemical fertilizers under the same conditions. Generally, these results undoubtedly confirm that dual bio-fertilizers could replace the use of chemical fertilizers and consequently improve the quality and quantity of D. regia.   Key words: Delonix regia, Arbascular mycorrhizae fungi, Azotobacter chroorcoccum, yeast strains - growth characters, chemical composition.