Categories of resistance in national uniform wheat yield trials against Schizaphis graminum (Rondani) (Homoptera: Aphididae)

An effort was made to evaluate the categories of resistance in National uniform wheat yield trials (NUWYT) Normal (N) 2002-03 against green bug Schizaphis graminum, under controlled conditions. Aphids were collected from grasses and wheat field of National Agricultural Research Centre and their culture was established. Out of twenty NUWYT wheat cultivars six cultivars, MAW-I, SKID-I, V-99022, PR-76, 99-B-2237 and TD-I, were resistant. In seedling bulk test, twelve cultivars proved to be moderately resistant and two were susceptible. Components of resistance like antixenosis, antibiosis and tolerance were conducted to determine the nature of resistance in NUWYT (N) cultivars. In antixenosis test 99132460, MAW-I, D-98627 and V-5 were least preferred cultivars. In antibiosis three cultivars SD-66, Local Check (Wafaq-2001) and D 98627 sustained high fecundity and three cultivars 991324460, SKID-I and 99132237 showed high tolerance.