COMPARISON OF CANOLA (BRASSICA NAPUS L.) GENOTYPES UNDER DIFFERENT FARMING SYSTEMS FOR RESISTANCE AGAINST APHID SPECIES, BREVICORYNE BRASSICAE (L.), MYZUS PERSICAE (SULZER) AND LIPAPHIS ERYSIMI KALT. (HOMOPTERA: APHIDIDAE)

The hypothesis that plants supplied with organic fertilizers are better defended against insectherbivores than those supplied with synthetic fertilizers was tested over two field seasons. the study was carried out in the farm area of university of agriculture, faisalabad on 11 canola genotypes grown under three farming systems i.e. synthetic fertilizer, farm yard manure and control laid out in randomize complete block design. sampling for aphids was done weekly from late february to late march from top 10 cm inflorescence of plant. three aphid species i.e. brevicoryne brassicae, myzus persicae and lipaphis erysimi were recorded on genotypes. none of the genotype was completely free from aphids infestation. number of aphids among canola genotypes was not different, however highest aphid population was recorded on the genotype cyclone while minimum population was on the genotype hyola 401 and rainbow and rest of genotypes showed intermediate response against aphids. different farming systems showed significant effect on the aphids infestation. the highest aphid attack was recorded on the canola grown under fertilizer application followed by those genotypes that were grown under farm yard manure application and control. our result suggests that application of synthetic fertilizer could increase aphid population while farm yard manure application may have the potential to reduce the aphid attack in the long term.