Genotypic Characterization of Azotobacteria Isolated from Argentinean Soils and Plant-Growth-Promoting Traits of Selected Strains with Prospects for Biofertilizer Production

Table 3

Effect of pure IAA solutions and Azotobacter inoculation on the number of seminal roots, and root colonization of 8-day-old wheat seedlings.

Treatment	IAA concentration μg mL^−1	Number of seminal roots per plant	Root colonization (cfu root^−1)
Water		4.33±0.12^c	—
Low-IAA	2	4.69±0.11^b	—
High-IAA	20	5.03±0.12^a	—
A. salinestris AT18	2.2	4.68±0.10^b	4.38 × 10^4 ± 1.68 × 10^4c
A. salinestris AT37	2.5	4.74±0.16^b	6.94 × 10^5 ± 2.67 × 10^5b
A. chroococcum AT25	14.8	5.18±0.18^a	1.26 × 10^6 ± 4.67 × 10^5a
A. chroococcum AT31	14.2	5.33±0.15^a	8.41 × 10^5 ± 1.87 × 10^5b
A. salinestris AT19	18.2	5.39±0.06^a	3.01 × 10^6 ± 1.12 × 10^6a

Pregerminated seeds were treated with water (Control), IAA pure solutions of 2 μg mL⁻¹ (Low-IAA) and 20 μg mL⁻¹ (High-IAA), or were inoculated with A. salinestris strains (AT18, AT19, and AT37) or A. chroococcum strains (AT25 and AT31). Values are means ± standard error of two independent experiments with three replicates (𝑁=6). Different letters in a column indicate significant differences between means as determined by the DGC test (𝑃=0.05).