POPULATION TREND OF APHID (Lipaphis erysimi Kalt) ON CANOLA (Brassica spp.) CULTIVAR IN PESHAWAR

Four canola cultivars viz, (durre-nifa, abasin, raya-nifa and bulbul) were tested for their resistance/tolerance against aphid (lipaphis erysimi) attack in randomized complete block design (rcbd) at the new developmental farm of khyber pakhtunkhwa agricultural university peshawar, during the rabi season of 2011. the results of overall mean revealed that minimum aphid infestation (25.48) leaf^-1 was recorded on canola cultivar bulbul and maximum aphid infestation (58.67) leaf^-1 was recorded on raya-nifa. similarly the highest aphid (30.19) infestation per 2.8 cm of inflorescence was recorded on the raya-nifa and the lowest number (12.19) of aphids/2.8 cm of inflorescence was recorded on bulbul. the cultivar raya-nifa could not tolerate aphid attack and resulted in stunted growth. bulbul resulted in maximum yield (3085.56), oil content (49.1), siliqua plant-1(117.96), 1000-seed weight (14.17), seed siliqua^-1 (22) and low aphid infestation. raya-nifa presented better result to plant height (127.215), protein content (23.5) and moisture content (4.0). it was concluded from the study that aphid population on all the tested cultivars fluctuated and non of the cultivar showed complete resistance to aphid during most of the season probably due to lack of antixenosis or antibiosis. however, the data on yield and other agronomical characteristics indicated that the cultivar bulbul possess some levels of resistance.