Seed biofortification with Azospirillum spp. for improvement of seedling vigour and productivity in rice (Oryza sativa L.)

Seeds of two vigour lots of rice cv. ASD 18, viz; high vigour (stored for three weeks) and low vigour (stored for 56 weeks under ambient conditions) were treated with mixed cultures of Azospirillum lipoferum and Azospirillum brasilense, a diazotrophic bacteria, to determine the efficacy on seedling vigour and productivity. Seed treatment with Azospirillum, increased the amylase activity, during germination. The enzyme level was more in high vigour seeds. Secretion of gibberellins by the bacterium may be the reason for this increase and subsequent hydrolysis, resulting in enhanced seedling vigour encompassing speed of germination, seedling length and dry weight. The positive effect of Azospirillum seed treatment observed on seedling vigour in the nursery has not improved the yield parameters significantly. The advantage observed on seedling vigour may enable the seeds to overcome stresses and can be recommended as a pre-sowing treatment.