author(s)
Siddhartha Shankar Sharma, Bablu Paul, Pratik Saha, Shyamal Kumar Sahoo, Kashinath Mandal, Tapan Kumar Hath and Hossain Ali Mondal

abstract
The present study aimed to identify parameters for probing the elevated levels of resistance among the Brassica genotypes in the field condition at the early time of aphid infestation. Four Brassica genotypes (abbreviated as B2, B3, B3 and B12) having elevated levels of resistance (B2≤B3˂B4˂B12) were considered. In the field condition, differential aphid inoculum, unsynchronized timing of aphid infestation, movement of aphid within field, and no competition of space & food in the host plant made elusive to probe the elevated levels of resistance. A few parameters can probe the elevated levels of resistance in open field condition at the early period of aphid infestation. These parameters are ‘Comparison of water content in aphid itself’ collected from genotypes having elevated levels of resistance, ‘Comparison of water content between aphid probed twig and aphid unprobed twig’, and ‘Comparison of water content in aphid probed twig and aphid itself’ could potentially differentiate the elevated levels of resistance at the early time point of aphid infestation. The present study identified few novel parameters that could be potentially explored in Brassica-Aphid interaction biology from the early time of infestation to probe the resistance level in temporal scale.