Laboratory Protocol for Induction of Sporulation in Phytophthora cajani causing Phytophthora Blight in Pigeonpea

Background: Phytophthora blight (PB), caused by Phytophthora cajani is a prominent disease in the low laying areas combined with intermittent rainfall. Induction of zoospores and sporangia of P. cajani in culture plate is troublesome and also limited information is available on the protocol for sporulation of sporangia and zoospores in the laboratory, The study developed and validated the protocol for induction of sporangia and zoospore of P. cajani. Methods: The Protocol using 5-7 days old culture, diluted tomato extract broth and other culture conditions like the temperature of 30oC, alternate 12 hours of fluorescent light (2000 Lx) and dark can induce abundant sporangia and zoospores in vitro. Result: The study developed and validated the new protocol for uniform and profuse induction of sporangia and zoospores of P. cajani. Diplanetism mechanism of Phytophthora spp. was recorded with P. cajani the findings are the first of its kind. Additionally, the study revealed the concentration of 1x10-5 zoospores/ml is optimum to develop the infection in plants with the shortest incubation period of 24 hours.