ABSTRACT

Induced host plant resistance plays significant role in reducing insect pest pressure on plants. Application of silicon-based fertilizers has gained attention for enhancing plant tolerance to insect feeding, thereby reducing damage. Thus, investigation on the impact of silicon on major sucking pests and pink bollworm in cotton during the kharif 2023-24 was conducted at Main Agricultural Research Station, Dharwad.
Results revealed that, soil application of calcium silicate (Ca2O4Si) @ 200 kg/ha followed by foliar application of silicic acid (H4O4Si) @ 0.50 per cent, rendered superior efficacy with a higher reduction in thrips, leafhoppers, whitefly and aphids over control (68.56%), (64.12%), (65.69%) and (54.98%) with mean average of 14.20 thrips, 8.94 leafhoppers, 8.45 whitefly, 9.41 aphids per three leaves, respectively. In contrast, it could not be significant against pink bollworm and mirid bugs. Notably, highest silicon content in leaf (2.66 g/kg), flower (1.52 g/kg) and cotton boll rind (1.65 g/kg) were observed, while the control and chemical check treatments showed lower silicon levels (0.68 g/kg and 0.70 g/kg), respectively.
Conversely, soil application of calcium silicate at 100 kg/ha and foliar application of silicic acid at 0.25 per cent was found to be the least effective with respect to sucking pests and pink bollworm. Soil application of Ca2O4Si @ 200 kg/ha followed by foliar application of H4O4Si @ 0.50 per cent recorded higher yield of 11.57 q/ha, net returns of Rs. 29,177 per ha and B:C ratio of 1.51. Silicon induced resistance could be exploited in cotton IPM with confirmation.