INDOLE ACETIC ACID (IAA) PRODUCTION POTENTIAL OF PGPR BACTERIAL ISOLATES AND THEIR EFFECT ON SEED GERMINATION IN ZEA MAYS L.

The study was conducted to determine the presence of indole-3-acetic acid (IAA) in PGPR isolates using PCR reactions and biochemical tests. Positive isolates were tested under in-vitro conditions for germination efficiency on maize (Zea mays L.) seeds. Salkowski method was used for IAA tests on 30 bacterial isolates with PGPR properties. The KH14.3 and KH24.1.2 isolates were biochemically active in terms of IAA test. The absorbance readings were made at 595 nm using microplate reader and resultant values were compared to an IAA standard. IAA production of isolates varied between 0.42-6.37 μg/ml. For germination experiments, 20 maize seeds were coated with IAA- positive isolates (1.3x107 cfu/ml) in petri dishes in triplicates according to the randomized plot design. The germination test was monitored for 7 days in an incubator at 25°C. Experimental data were subjected to analysis of variance (one-way ANOVA). The difference between the bacterial coating and control group was significant at the level of P≤0.05. Germination efficiency was determined as 99.9% for KH14.3 and 2.7% for KH24.1.2. Present findings revealed that KH14.3 was ACC deaminase, phosphatase, and siderophore-positive and KH24.1.2 was positive for ACC deaminase and phosphatase. These two isolates were also biochemically active in terms of IAA and could increase germination success by coating on seeds.