Drip-applied rhamnolipid ameliorates soil physicochemical properties and enhances cotton yield under dry sowing with wet emergence cultivation

Abstract

Water scarcity and soil salinization are pivotal challenges constraining the sustainable development of the cotton industry. The synergetic application of dry sowing with wet emergence irrigation technology and rhamnolipid mediated technology has shown remarkable potential in reducing pre-sowing water requirements and mitigating soil salinity, while concurrently enhancing cotton growth and yield formation. This study investigates the impact of three irrigation frequencies high (F3), medium (F5), and low (F7) and three rhizomiclipid concentrations 0 (CK), 200 (RL), and 400 mg ·L⁻¹ (RH) on soil physicochemical properties, cotton emergence rates, and yields under dry sowing with wet emergence irrigation conditions (DSWE). The results demonstrate that irrigation frequency and rhamnolipid concentration significantly influence soil characteristics and cotton growth (P < 0.05). Specifically, under dry sowing with wet emergence irrigation conditions with a 5-day irrigation interval (F5) and 200 mg ·L⁻¹ rhamnolipid concentration (RL), soil salinity indicators such as electrical conductivity (EC) and pH, along with sodium ion (Na⁺) content, were substantially reduced. Concurrently, soil potassium ion (K⁺) content and enzymatic activities, including catalase (CAT), alkaline phosphatase (AKP), sucrase (SC), and urease (UE), were notably elevated. These modifications contributed to enhanced cotton emergence rates and increased yields. The partial least squares path modeling (PLS-PM) analysis demonstrated that both irrigation frequency and rhamnolipid (RL) drip concentration could directly and significantly affect the soil environment, which in turn directly or indirectly influenced cotton germination rate, biomass, and yield. This research underscores the potential of integrating dry sowing with wet emergence irrigation with rhamnolipid applications to address water scarcity, achieve high water-use efficiency in cotton cultivation, and support sustainable agricultural practices. The findings provide both theoretical underpinnings and practical guidance for advancing water-efficient and sustainable cotton production systems.