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Abstract

Two host plant resistance trials were conducted at Central Cotton Research Institute, Sakrand Sindh during 1997 cotton season to assess in-built tolerance of sucking as well as bollworm complex in new varieties developed by different brecders of Pakistan. The results demonstrated minimum population per leaf of thrips and jassid on CRIS-7A the densely hairy varicty, whereas minimum population per leal of whitefly was recorded on CRIS-83 the glahrous varicty proving negative correlation between jassid and hairiness. The maximum per leaf population of thrips. jassid and whitely was observed on CRIS-105, CRIS-5A and CRIS-7A respectively. The maximum bollworm damage was noted in CRIS-56 and minimum in CRIS-5A. Highest seedeotton yield (2296 kg ha") was produced by CRIS-9 whereas lowest (1435 kg ha") by CRIS-78. Results of second trial revealed that thrips and whitefly population was below economic injury level and non-significant in all the varieties. However, jassid population was above economic injury level and significantly higher on MNH-427 variety whereas CRIS-82 recorded minimum. Variety MNH-465 recorded highest bollworm damage percent and CRIS-133 lowest. Highest seedeotton yield of 4555 kg hat was produced by CRIS-134 whereas lowest (1531 kg ha") by DNH-40.

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