Response of sorghum (Sorghum bicolor L.) to plant growth hormones produced by Aspergillus sp.

 In this study, 10 isolates of Aspergillus fungus were isolated from the soil of the rhizosphere and roots of rice, sorghum and barley plants that were cultivated in the areas of Thi-Qar Governorate, Iraq. The types of isolates were identified by studying their biochemical, morphological, and microscopic characteristics. The results showed that all isolates belong to the genus Aspergillus. The study also estimated the quantity of growth hormones produced by the studied isolates. The study found that 5 isolates, labeled as P1, P2, P5, P7 and P9, had a high efficiency in secreting growth hormones. To determine the effect of growth hormones of Aspergillus fungus on plant growth, a potted experiment was conducted using a completely randomized design (CRD) with three replications. The bio-inoculation increased the plant height, dry weight of the vegetative/root parts and root length by 34.15%, 45.77% and 34.97%, respectively compared to control treatment. Likewise, the percentage of nitrogen in bio-inoculated sorghum leaves, vegetative roots and root parts increased by 26.39%, 29.56% and 33.15%, respectively compared to the control treatment where no inoculation was done.