Silicon Retention in Soil and Sugarcane Cultivar and its Impact on Stalk Borer (Chilo auricilius Dudgeon), Yield and Quality Indices in Northwest India

Sugarcane is a long duration important cash crop in India which is harvest after 10–18 months. Amongst various biotic and abiotic stressors affecting sugarcane, sugarcane stalk borer Chilo auricilius causes huge economic losses in yield and quality parameters. No synthetic chemical is effective against stalk borer due to its internally feeder habitat. Therefore, one ecologically sound best management practice in sugarcane is application of silicon to mitigate against stalk borer. Various sources of silicon viz. T1, T2, T3 and T4 were of silicon material (SM) 50% @ 8, 10, 12 and 15 kg/acre, respectively; T5 and T6 were of rice husk ash (RHA) @ 200 and 400 kg/acre; T7 and T8 were of bagasse ash (BA) @ 200 and 400 kg/acre; T9 Trichogramma chilonis @ 20,000 eggs per card (12 releases) and T10 untreated control were evaluated for retention in soil, plant and impact on stalk borer, cane yield and quality traits in sugarcane cultivar CoPb 98. In soil, silicon persistence decreased over the time in T4 at 0 (209.82 ± 1.28 mg kg−1) and 300 days after planting (DAP) (126.94 ± 4.49 mg kg−1), respectively. In sugarcane stalks, the uptake of silicon increased over days (T4) 1.84 ± 0.07 and 2.50 ± 0.32 mg kg−1 at 0 and 300 DAP, respectively. Stalk borer incidence (%) reduced significantly in T4 (12.89 ± 0.77%) compared to control (21.33 ± 1.33%) (p ≤ 0.000). Cane traits viz. cane length, per cent germination, number of millable cane/clump, single cane weight, yield increased significantly with the application of silicon. Juice quality traits such as Brix, Sucrose, Commercial cane sugar, CCS and CCS %, were also enhanced significantly in CoPb 98. As observed in the scanning electron microscope (SEM), third instar stalk borer larvae on the Si+ stalks eroded their mandibles with feeding on silicon enriched tissues. The cost-benefit ratio showed that among the SM the highest B:C ratio 1.74 in (T4) SM 50% @ 15 kg/acre was at par 1:73 with 12 kg/acre (T3) in terms of reducing stalk borer infestation and significantly increase cane yield and quality traits. Therefore, SM 50% @ 12 kg/acre can be used for the management of stalk borer and also be vibrant part of integrated pest management in sugarcane crop.