Effect of population levels of Thrips tabaci on different plant characters in cotton

摘要

A field experiment was conducted to study the losses in cotton due to Thrips tabaci during 2013 at Entomological Research Farm, Punjab Agricultural University, Ludhiana. The nature and extent of losses due to T. tabaci, were determined at seven initial levels viz., 0, 50, 100, 150, 200, 250 and 300 thrips per plant were kept as treatments. Observations recorded to estimate the nature and extent of losses were number of leaves per plant, number of damaged leaves per plant, leaf size, internodal length, plant height, number of sympods, number of monopods, number of squares, number of flowers, number of bolls, number of pickable bolls, seed cotton yield and root size. All the plant characters tended to decrease with increasing population level except the number of damaged leaves, which kept on increasing with increasing population level. Different levels of thrips population caused significant effect on all the characters except on the number of monopods. Yield loss of 2.4, 4.6, 5.2, 7.1, 9.4 and 11.9per cent were observed in case of treatments with 50, 100, 150, 200, 250 and 300 thrips per plant, respectively.