Potassium nutrition of cotton (Gossypium hirsutum L.) in relation to cotton leaf curl virus disease in aridisols

A greenhouse experiment was conducted using four cotton (Gossypiuln hirsutuln L.) cultivars (CIM-448, CIM- 1100, NIAB-Karishma, S-12), four rates of potassium (0, 62.5, 125.0, 250.0 kg K ha-1) and two sources of potassium [sulphate of potash (K2SO4) and muriate of potash (KCl)] to determine response of potassium fertilizer in relation to infestation of cotton leaf curl virus disease (CLCuV), a whitefly (Bemisia tabaci Germadius) transmitted geminivirus (genus Begomovirus) at the Central Cotton Research Institute, Multan, Pakistan. There were significant differences among the cultivars in incidence and intensity of CLCuV disease. The cultivars CIM-448 and CIM-1100 showed complete resistance to CLCuV, whereas cv. S-12 was highly susceptible and cv. Karishma moderately tolerant to the disease. There was 12 to 38% reduction in the disease incidence as a result of addition of 250 kg K ha(-1). The incidence and intensity of CLCuV disease were little affected due to the different sources of potassium fertilizer. The mild intensities of CLCuV disease in cv. NIAB-Karishma at day 30, 60 and 90 after planting were negatively correlated with increasing doses of potassium fertilizer. The relationship between intensity of CLCuV disease at day 90 after planting and potassium doses for cv. S-12 could be described by the regression equation (Y= 60.40-0.064x, r= -0.46**).