Rice husk ash and imidazole application enhances silicon availability to rice plants and reduces yellow stem borer damage

Abstract

Silicon (Si) has been implicated to reduce damage by rice pests. In this study we validate the field efficacy of rice husk ash (RHA) and imidazole, alone and in combination, against damage by yellow stem borer (YSB) under field conditions for two seasons in five rice cultivars. Field application of RHA and imidazole, either alone or in combination, enhanced Si deposition (43–59.8 mg g−1) in stem tissues of rice plants as compared to untreated control (30.2 mg g−1). Deposited Si caused significant wearing of mandible incisors, and lowered larval density, thereby decreasing YSB damage and increasing the grain yield significantly. RHA and imidazole did not alter the total sugars and total phenol content in rice cultivars. Field application of imidazole along with RHA at vegetative phase and again at booting stage was on par with insecticidal treatment (carbofuran 3G) with respect to per cent damage, larval density and grain yield. The B: C ratio in the Si treatments varied from 1.16 to 1.31 and T4-RHA + imidazole (applied twice) was at par with one granular insecticide application (1.32) but higher than the untreated control (1.0). RHA and imidazole can be integrated as one of the eco-friendly components in the present scenario of climate change for the management of YSB in rice.