author(s)
Ratan Lal Sharma and RR Ahir

abstract
Tomato (Solanumly copersicum L.) ranks first among processing crops. Tomato is the world’s second most consumed vegetable after potato. Alternaria blight of tomato caused by Alternaria alternata is one of the most important fungal diseases prevalent in tomato growing areas of India particularly in Rajasthan state and is considered as one of the limiting biotic factor for successful cultivation of tomato. Physiological studies were conducted in the laboratory of Department of Plant Pathologyat SKNAU, Jobner on Alternaria alternata. Results revealed different levels of relative humidity and temperature play a significant role in my celial growth of Alternaria alternata. In vitro studies of different levels of relative humidity reveals that, 90 to 100 per cent relative humidity produce maximum my celial growth 88.70 mm and 85.10 mm, respectively. In temperature studies maximum mycelium growth of Alternaria alternata was observed at 25ºC followed by 30 and 35 ºC.