Agriculture is the backbone of Indian nation. Climate and technology are the parents for agriculture. Agriculture in Tamil Nadu is unique in its character, with respect to climate. It has varied agro-climatic zones which favors for the growth of various types of crops in the country. On the other hand it also depends on technology. Hence the present study was planned to analyse the performances of selected crops with respect to the technology. For this study, blackgram crop was purposively selected. Similarly out of five agro climatic zones, one district in each zone were purposively selected. Secondary data from the period 1990-1991 to 2009 -2010 were employed for the study. The result shows that area and production was increasing in the selected districts except in Salem and Erode districts. The productivity of blackgram was decreasing in post introduction period in the selected districts except in Erode district. For area under blackgram crop the instability decreased except in Thanjavur and Virudhu Nagar districts. In production the instability was increased in post-introduction period when compared to pre-introduction period. In productivity, the instability was increased in the selected districts except in Villupuram and Salem districts. Based on the agro climatic zone categorization, North Eastern Zone - Villupuram district and Western Zone - Erode district were identified as safe zone for blackgram.