Infusing Microbial Consortia for Enhancing Seed Germination and Vigour in Pigeonpea ( Cajanus cajan (L.) Millsp.)

Use of plant growth promoting bacteria for seed treatment is in trend nowadays as it is beneficial to the plants and environment. But, carrier-based inoculants have short shelf life and difficult to use for large quantities of seed. Therefore, in the present study we used liquid microbial cultures for seed infusion in pigeonpea and assessed their compatibility with seed treating chemicals. The results showed that the soaking of pigeonpea seeds in liquid cultures like pink pigmented facultative methylotroph (PPFM) @ 1 : 100 dilution for 3 h or Rhizobium or phosphobacteria @ 1 : 50 dilution for 4 h have showed increased germination and vigour. In the microbial infused seeds, Rhizobium (13 × 10⁴ cfu g^–1 of seed) and phosphobacteria (20 × 10⁴ cfu g^–1 of seed) populations observed, were slightly reduced during three months storage. Nevertheless, the population was drastically reduced in PPFM (11 × 10⁴ to 2 × 10⁴ cfu g^–1 of seed). Conversely, PPFM has performed better in seed quality enhancement amongst cultures. Also, consortia of Rhizobium @ 1 : 50 dilution + PPFM @ 1 : 100 dilution (1 : 1) for 3 h increased seed vigour with better microbial populations (14 × 10⁴ and 2 × 10⁴ cfu g^–1 of seed). Also, seed infusion with PPFM liquid culture @ 1 : 100 dilution for 3 h followed by polymer coating @ 5 ml kg^–1 + carbendazim treatment @ 2 g kg^–1 of seed recorded increased germination and vigour with the PPFM population of 1 × 10⁴ cfu g^–1 of seed.