Soybean genotype performance and seasonal stability in relay cropping with chili on coastal sandy soils

Soybean production in Indonesia is constrained by land competition, yet coastal sandy soils planted with high-value chili offer a niche for soybean via relay cropping. We evaluated five varieties (Anjasmoro, Dena 1, Demas 1, Malika, Grobogan) in an irrigated soybean–chili relay at Samas, Indonesia, across two seasons in 2023 (CS1: January–May; CS2: July–October) using a randomized complete block design with three replications. Analysis of variance (ANOVA) and genotype-by-environment (GGE) biplots assessed genotype × environment interaction (GEI), and a Random Forest model with permutation importance identified agronomic predictors of seed weight per plant (SWP). Results showed that ANOVA detected significant GEI for SWP and several traits, and GGE grouped varieties as: (1) high-to-moderate yield with stability (Anjasmoro, Dena 1), (2) high yield with lower stability (Malika, Demas 1), and (3) low yield with relative stability (Grobogan). Random Forest ranked predictors as plant height >100-seed weight > pods per plant > seeds per plant > leaf area, indicating that canopy architecture and seed mass, supported by number components, underpin performance. Under the tested irrigated coastal-sand conditions (CS1–CS2 at one site-year), Anjasmoro was the most promising, whereas Dena 1 exhibited the greatest stability at moderate yield; broader recommendations require multi-location, multi-year validation. Copyright © 2025. Published by Elsevier Inc.