Seed Coating with Bacteria-producing Indole-3-Acetic Acid (IAA) on Germination, Seedling Growth and Nutrient Contents of Vegetable Soybean [Glycine max (L.) Merrill]

Background: Several types of bacteria capable of producing indole-3-acetic acid (IAA) are commonly used for seed coating to enhance seed germination, vigor and seedling growth. This experiment aimed to study the effects of seed coating with three IAA-producing bacterial isolates on germination, vigor, seedling growth and nutrient content in seedlings. Methods: The experiment employed a completely randomized design (CRD) with four replications and five treatments: no coating (T1), coating with Carboxymethyl Cellulose (CMC) only (T2), coating with Enterobacter kobei (isolate 1) (T3), coating with Enterobacter kobei (isolate 2) (T4) and coating with Burkholderia paludis (isolate 3) (T5). Laboratory and greenhouse tests were conducted to evaluate the effects on germination and seedling growth. Result: The results revealed that three bacterial isolates Enterobacter kobei (isolate 1), Enterobacter kobei (isolate 2) and Burkholderia paludis (isolate 3) produced high levels of IAA. Seed coating with these isolates significantly enhanced germination and mean germination time under laboratory and greenhouse conditions. Seeds coated with E. kobei (isolate 1) showed significantly greater shoot and root lengths at 10 days than non-coated seeds and higher accumulation of nitrogen, phosphorus, potassium and calcium in the seedlings. Consequently, seed coating with E. kobei (isolate 1) is recommended for vegetable soybean seeds to improve germination, vigor and seedling growth.