Silicon uptake and accumulation as a nutrition in sugarcane for resistance against top borer Scirpophaga excerptalis Walker (Crambidae: Lepidoptera), its influence on larval mandibles and commercial cane traits

Abstract Top borer is a major pest of sugarcane which adversely affects the cane yield and sugar recovery. However, the mineral nutrient status of plants plays a crucial role in providing resistance to herbivores since they are quite sensitive to changes in host plant nutrition. In the current finding, the effect of various silicon sources (silicon material (SM) 50% @ 15, 12, 10 and 8 kg/acre, rice husk ash (RHA) @ 200 and 400 kg/acre and bagasse ash (BA) @ 200 and 400 kg/acre) at varied doses on the % incidence of top borer, cane yield and quality traits in sugarcane cultivar Co 238 was studied. The addition of silicon significantly (p ≤ 0.05) enhanced the silicon concentration in sugarcane stalk and soil (available form). The incidence of top borer (TB) was reduced significantly (p ≤ 0.05) up to a maximum of -37.62%. Cane yield and its attributes were significantly (p ≤ 0.05) increased with the application of silicon except for germination (p ≥ 0.05). Juice quality traits such as Brix (% soluble solids in juice), Sucrose (%), Commercial cane sugar (CCS q/acre) and Pol% cane were also improved significantly (p ≤ 0.05) in a tested cultivar with the addition of silicon. With the increase in the number of days after planting the stalk silicon content increased maximum up to 2.48% (T4) and the available soil silicon level decreased. The correlation analysis revealed that stalk silicon content has a significant (p ≤ 0.05) strong negative association (r= -0.959) with % infestation of TB and a strong positive (0.86 < r > 0.95) association with all cane yield and juice traits (brix, sucrose, CCS and pol% cane). The TB larvae feeding on silicon-rich tissues with deposited silicon as phytoliths (SEM images) have worn-out mandibles. Economic analysis showed that SM 50% @ 12 kg/acre was sufficient for reducing the infestation of TB up to 35.67% along with enhancing cane yield (50.82%) and CCS (56.73%). Hence, silicon could be used as a vital component for the integrated management of TB.