Study on infestation rate of new cotton lines to important pests-sucking in Golestan province

Cotton plant is invaded by several sucking insect such as thrips ,aphid ,whitefly ,bugs and leaf hopper in northern part of Iran ,Golestan province. As introduction of in proved cotton cultivar with higher yield is the main object of cotton research institute,so it is important to screen the supreme lines with suitable tolerance to sucking insect. This study was carried out in cotton research station of Hashemabad (Gorgan) in during 2007and 2008 as complete randomized block design (CRBD) with 17 treatments and 4 replicationsin plots without pesticide spraying by 110 ×30 meters areas. Samplings was done weekly on 10 plants which were selected randomly and in each plant 3 leaves from top ,middle and bottom were inspected for counting and reading of important sucking insects including thrips,aphid and whiteflyand leaf hopper) was counted and rerecorded. The data was analysis by Excel. Bases on mean comparison of infestation rate of new cotton lines to sucking pests and also regarding to yield and earliness percent, tolerant lines includedTtabladila×Sahel-180,N200×Gukorova-80, Tabladila×Sahel-60,Siokra×Tabladila-133, Tabladila×Sahel-174,Siokroa×Tabladila-134were selected and future breeding programwill be done in view.