Effect of silicon against pink bollworm, (Pectinophora gossypiella ) in Bt cotton

Abstract

Cotton (Gossypium hirsutum L.) stands as the primary fibre crop globally, particularly vital for the textile industry across numerous nations. However, cotton is notorious for its susceptibility to various insect pests and diseasesand Bt cotton, in particular faces challenges from pink bollworm. Addressing this issue, the application of silicon-basedfertilizers has gained attention for enhancing plant tolerance to insect feeding, thereby reducing damage. Although, Silicon(Si) is the second most abundant element in the earth’s crust, to benefit plants, it must be absorbed in the form of silicic acid,which, upon absorption, forms hard structures known as phytoliths within plant tissues. These phytoliths fortify cellwalls throughout the plant, increasing toughness and defending against both biotic and abiotic stressors. Thus, investigationon the impact of silicon on pink bollworm incidence in cotton during the kharif 2023-24 was conducted at Main Agricultural Research Station, Dharwad. The results revealed that among the silicon-based treatments, soil application of calciumsilicate at a rate of 200 kg/ha followed by foliar application of silicic acid at 0.50 per cent, showed less significant effect witha mean average of 8.37 per cent flower damage, 41.28 per cent green boll damage and 10.88 number of larvae per ten bolls. Conversely, soil application of calcium silicate at 100 kg/ha and foliar application of silicic acid at 0.25 per cent were foundto be the least effective with respect to pink bollworm incidence. However, there was higher reduction of pink bollwormincidence in chemical treatments compared to silicon-imposed treatments. Notably, soil application of calcium silicate at arate of 200 kg/ha followed by foliar application of silicic acid at 0.50 per cent exhibited the highest silicon content in flower(1.52 g/kg) and cotton boll rind (1.65 g/kg), while the control and chemical check treatments showed lower silicon levels.