Validation of Screening Technique for Cotton Bacterial Blight Resistance under Controlled Condition

Abstract

Seven different methods of artificial inoculation such as 1. Carborundum injury, 2. Pin prick injury 3. Sand paper injury, 4. Syringe inoculation on lower surface of leaf without needle, 5. Syringe inoculation of veins on lower surface of leaf with needle, 6. Tooth picks inoculation on collar region and 7. Pressurized spray inoculation were evaluated to find out the efficient and precise screening method for cotton bacterial blight caused by Xanthomonas citri pv. malvacearum under controlled conditions (plant growth chamber). Inoculated seedlings were incubated at 28°C, 90% RH and 3000 LUX light intensity during day time and 22°C, 90% RH and absence of light during night time for symptom development. Among them, pin prick injury recorded maximum PDI (64.25) in 20-24 days post inoculation followed by sand paper injury (56.50 PDI) in 23-27 days post inoculation on 20 day old LRA 5166 cotton seedlings compared to other methods. Both these methods developed all types of symptoms. Initial symptom of water soaked lesion was appeared in 7-8 days post inoculation in pin prick injury while it was 9-10 days in sand paper injury.