author(s)
Ruidar Ali Shah,Imtiaz Ali Khan

abstract
The experiment to evaluate the onion cultivars against Thrips tabaci infestation was conducted at Agricultural Research Institute Tarnab Peshawar, Pakistan during 2011-12. Eight onion cultivars (Ambika, Swat-1, Trichmir, Barkel, Macarena, Red ball, Granada Red and Sunset were assessed to determine the most tolerant cultivar against T. tabaci infestation. T. tabaci populations were monitored on weekly basis on onion plants under natural field condition. T. tabaci infested all the cultivars more or less, however highest numbers of thrips plant-1 were recorded in Trichmer (10.99 thrips plant-1) and lowest (5.98 thrips plant-1) were recorded in Swat-1. Highest plant height (64.35 cm) was recorded in cultivar Trichmir and lowest (38.40 cm) was recorded in Macarena. Highest (13.07) number of leaves plant-1 was recorded in Trichmir and lowest (7.66 leaves plant-1) was recorded in Granada red. Trichmir was (94.04%) the most succulent cultivar followed by Sunset (91.38%), Ambika (87.21%) and (86.49%) in cultivar Swat-1. The maximum yield (18.56 tons ha-1) was obtained from cultivar Swat-1 and minimum was from Ambika (9.34 tons ha-1). Number of leaves, plant height, high succulency and color favored high infestation.