SURVIVAL AND DEVELOPMENT OF AMERICAN BOLLWORM, Helicoverpa armigera (HUBNER) ON BT COTTON HYBRIDS OF DIFFERENT BT EVENTS

No. Poster–73 IMPACT OF COTTON LEAF CURL DISEASE (CLCuD) ON YIELD AND QUALITY OF FIBRE IN Bt COTTON IN PUNJAB Daljeet Singh, J.S. Gill, R.K. Gumber and Ramandeep Singh Punjab Agricultural University, Regional Station, India Cotton is one of the most important cash crops in India. Cotton leaf curl disease (CLCuD) , caused by a single stranded circular Gemini virus consisting of DNA A and two satellites i.e DNA-1 and DNA beta and transmitted by white fly (Bemisia tabaci) is a serious problem in northern India. During the last three years, the productivity of cotton has suffered to a great extent due to CLCuD in Punjab. The initiation of disease is characterized by SVT type symptoms on young upper leaves of plants. Upward /downward leaf curling followed by formation of cup shaped leaf laminar out growth of veinal tissue on the abaxial side of the leaves are other important symptoms. In severe cases reduction of internodal length leads to stunting growth and reduced flowering /fruiting. Depending upon the severity of infection in the susceptible varieties, the disease caused 90.0% losses in seed cotton yield. Besides reduction in seed cotton yield, this malady deteriorates quality characters of the fibre remarkably. Therefore, the present study was conducted to estimate the losses in seed cotton yield and fibre characters of Bt-cotton hybrids due to CLCuD. The experiment was conducted for two years from kharif 2009 to kharif 2010 seasons at Punjab Agricultural University, Regional Station, Faridkot. The pooled data over two years indicated that the CLCuD has resulted in a reduction of 52.7% in number of bolls and 54.2% in boll weight in Bt cotton hybrid RCH 134. Similarly, it reduced the fibre length from 29.1 mm to 26.2 mm (9.9%); fibre uniformity from 68.9% to 68.1% (1.1%); fibre strength from 29.1 g /tex to 26.9 g /tex (7.5%) and miconaire value from 5.2g /inch to 5.0 g /inch (3.8%). Similar results were reported in another Bt cotton hybrid MRC 6304, where the disease reduced the boll number by 46.1% and boll weight 43.4%. With regard to fibre quality, the disease decreased the fibre length from 29.6 mm to 29.4 mm (0.67%); fibre uniformity from 66.9% to 65.8% (1.6%); fibre strength from 31.0 g /tex to 29.5 g /tex (4.8%) and micronaire value from 4.5 g /inch to 4.3 g /inch (4.4%). Therefore considering the impact of disease on yield and fibre quality, it must be managed using integrated disease management (IDM) strategies, to avoid huge quantative and qualitative losses in upland cotton.