Production of Plant Growth Regulators by Some Fungi Isolated under Salt Stress

Abstract

Fifty-eight fungal isolates were isolated from salt soil, whey and salt fish on medium supplemented with 0.5% NaCl. Out of 58 isolates, 49 were capable to grow on medium supplemented with 1 % NaCl. These halo-tolerant isolates were tested to produce plant growth regulators (PGR) on solid or in broth medium. On solid medium, 9 halo-tolerant isolates out of 58 isolates were gave indole acetic acid (IAA) which appeared red zone around growth zone with index ranged from 0.25 to 0.56. While in broth medium, 9 isolates were tried to produce IAA and gibberellic acid (GA) in presence of NaCl at 0.5 or 1%. The maximum IAA and GA production were obtained by FS12 isolate (4.32 and 4.52 mg/100ml) and by FW2 isolate (2.71 and 2.92 mg/100ml) at 0.5% and 1% NaCl, respectively. FS12 was selected as the most efficient isolate for plant growth regulators (PGR) production and identified as Aspergillus niger. Carbon and nitrogen sources were studiedfor PGR optimization by the tested strain. Whey and peptone were used as a sole carbon and nitrogen source, where increased the IAA and GA production about 15.4% and 71.3% as compared to control (basal medium).