Effect of soil amendments on growth, physiology and productivity of rice under moisture stress

Abstract

Increasing water scarcity and erratic rainfall pose major challenges to rice productivity, particularly during critical growth stages. Soil amendments that improve soil water availability and plant water relations may help sustain crop productivity under moisture stress. A pot culture study was conducted at the Instructional Farm, College of Agriculture, Vellanikkara, Kerala, to evaluate the effectiveness of soil amendments in mitigating moisture stress and improving rice productivity. The experiment was conducted in a factorial completely randomized design with three replications, comprising five soil amendments and three moisture regimes. The amendments included silica @ 100 kg ha-1, biochar @ 5 t ha-1 (rice hull ash), hydrogel @ 2.5 kg ha-1 (Pusa hydrogel), 25% additional potassium over the recommended dose (45 kg ha-1) applied in two splits, and an unamended control. The moisture regimes were 50% field capacity (FC) throughout crop growth, moisture stress at maximum tillering and panicle initiation, and no moisture stress. Soil amendments significantly influenced growth, physiological responses and grain yield. Under 50% FC, silica application resulted in higher plant height, fresh shoot weight and dry matter production, while hydrogel improved relative water content and chlorophyll content. Under no moisture stress, 25% additional potassium recorded the highest grain yield (27.13 g plant-1). Under 50% FC and stress at maximum tillering and panicle initiation, silica @ 100 kg ha-1 recorded the highest grain yield, followed by biochar @ 5 t ha-1. The findings indicate that appropriate soil amendments can help sustain rice productivity under moisture stress, with their effectiveness varying according to the moisture regime.