Induction of Systemic Resistance in Cotton by the Neem Cake and Pseudomonas Aeruginosa under Salinity Stress and Macrophomina Phaseolina Infection

Induction of systemic resistance by neem cake (Azadirachta indica) and endophytic Pseudomonas aeruginosa, a plant growth promoting bacterium, was evaluated in cotton (Gossypium hirsutum L.) under salinity stress and fungal infection. The combination of biocontrol agent and organic matter induced tolerance against fungal infection (Macrophomina phaseolina) and salinity stress (EC= 17.3 dS, m) by producing salicylic acid 6.9–8.6 mg/ mL as compared to 2.8–4.6 mg/mL in control plants in field experiment, while polyphenols was found 3.1–3.7 mg/mL in neem cake + bacteria treated plants as compared 2.7–2.9 mg/mL in control plants. Cotton plants inoculated with M. phaseolina showed maximum infection in control plants (75%), while 37.5% plants were found infected in neem cake + P.aeruginosa treatment in field experiments. A significant (p<0.05) increase in shoot length was observed in combined treatment of neem cake + P.aeruginosa (30.5– 31.7 cm) compared to control plants (25.7–26.7 cm) kept under biotic or salinity stresses. Similarly, free radical scavenging activity was found highest in plants received P.aeruginosa in neem cake amended soil in both DPPH (2, 2-diphenyl-2picrylhydrazyl) and ABTS (2,2 –azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) methods. Similar results were also observed in screen house experiment. Application of endophytic P.aeruginosa in neem cake amended soil hold promise for the induction of systemic resistance in cotton.