Effect of inoculation of strains with ACC deaminase isolated from vermicompost on seed germination and some physiological attributes in maize (zea mays l.) exposed to salt stress

Bacterial inoculation containing 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity can induce stress tolerance in maize. Vermicompost is a rich source of growth promoting microbes, probably with a unique source for bacteria having ACC deaminase activity. The present investigation aimed to isolate strains with ACC deaminase activity from vermicompost and quantify their effects on seed germination and seedling growth of maize under salt stress. The ACC deaminase-producing strains were isolated from the vermicompost by the directional enrichment screening method. The 16S rDNA gene sequence homology analysis combined with physio-biochemical characteristics were used to identify the taxonomic status of. SB was identified as Stenotropho monas sp., RC and RF were Raoultella sp., and KE was Klebsiellas sp. Maize seeds were germinated under varying level of salinity stress (level of salt stress in 0, 50, 100, 150 and 200 mM NaCl solution). Salinity stress reduced seed germination rate, embryo length and root lengths of seedlings of maize. The results showed that inoculation with four isolated bacterial strains improved seed germination and the growth of maize seedlings under the level of salinity stress in 150 mM NaCl solution. Growth improvement in maize seedlings was associated with increase in proline, chlorophyll content. Therefore, strains with ACC deaminase activity can effectively alleviate the damage to corn seeds and seedlings under salt stress. (author)