Effect of silicon fertilizer on resilience against the fall armyworm and maize (Zea mays L.) yield

Abstract

Silicon nutrition is known to enhance plant resistance against insect pests and thus can be used as a tool to improve management of the fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), on maize. The FAW is the most destructive invasive species of pest that has impacted every corner of the Africa, causing significant harm to major crops such as maize, sorghum, millet, and legumes.Multi- location experiments were conducted in the districts of Mayuge, Tororo (eastern Uganda) and Wakiso (central Uganda). The experiments were arranged in a Randomized Complete Block Design (RCBD) with eight replications and Longe 5 maize variety was used as the test crop. In part one of the experiment, the treatments were silicon [Si (OH)4] alone, silicon in combination with pesticide Eminent, pesticide Eminent alone and control. In part two of the experiment, five rates (mL/20L) of silicon (0, 5, 10, 15, 20) were the treatments. Both treatments were applied 21 days after planting (DAP) after natural infestation of FAW and 31 DAP for seasons 2019A and 2019B. Data were collected on the number of FAW larvae, FAW damage severity, and number of lady birds, larvae population growth rate,leaf strength and yield. Silicon application negativelyaffected fall armyworm. Plants that received Silicon were less damaged. Application of silicon alone or in combination with pesticide Eminent reduced fall armyworm damage and FAW larvae in maize (56% and 36%). Silicon reduced FAW larvae (26%) and negatively impacted FAW larvae population growth rate. Silicon rate 15ml/20L (1L/Ha) gave the highest maize yield response. Application of Si to maize proved to be effective in controlling the FAW, probably due to induction of a biochemical defense line but also the creation of physical barriers that increase plant tissue hardness not necessarily the leaf strength.