Synergistic effect of Azotobacter and phosphate solublizing bacteria (PSB) inoculation on yield of Rabi sunflower under dryland conditions

A field experiment was conducted for four consecutive years to study the effect of seed inoculation of Azotobacter and phosphate solubilizing bacteria (Bacillus megaterium var. phosphaticum) on growth, yield and uptake of nutrients for rabi sunflower under dryland conditions. Among different treatments, seed inoculation with liquid Azotobacter and PSB @ 25 ml each kg⁻¹ seed recorded significantly highest plant height (149.6 cm), seed yield (11.36 q/ha), 100 seed weight (6.70 g), N uptake (46.35 kg/ha) and P uptake (8.75 kg/ha). As regards the effect of fertilizer levels, 75% recommended N and P₂O₅ recorded significantly higher plant height (150.0 cm), seed yield (11.45 q/ha), 100 seed weight (6.73 g), N uptake (47.68 kg/ha) and P uptake (9.02 kg/ha). Further, among the interactions, seed treatment with liquid Azotobacter and PSB @ 25 ml each kg⁻¹ seed coupled with 75% recommended N and P₂O₅ recorded highest seed yield (12.73 q/ha), benefit: cost ratio (1.75) and Azotobacter (16.50 x 10⁴/g soil) and PSB count (12.54 x 10⁴/g soil) in soil. The overall results showed that seed inoculation of liquid Azotobacter and phosphorus solubilizing bacteria significantly improved growth and yield parameters of rabi sunflower coupled with saving of 25% of recommended N and P₂O₅ dose of chemical fertilizers.