Plasticity in Flower Number and Abortion Shape Soybean ( <i>Glycine max</i> (L.) Merr.) Yield Under Different Environmental Stress

ABSTRACT Flower abortion in soybeans is a natural process that intensifies under adverse environmental stress conditions, particularly under high temperatures and water‐deficit conditions, leading to significant yield loss. This study aimed to evaluate the extent of flower abortion across a genetically diverse panel (MG III—IV) and quantify flower abortion under two different irrigation regimes. Two field experiments were conducted with a panel of 206 genotypes evaluated under 80% ET in 2023. In 2024, a representative sub‐set of 48 genotypes was tested under two irrigation regimes (80% and 40% ET). Flower number, pod number, flower abortion, and grain yield were recorded in both years, while plant height, node number, and seed number per pod per plant were recorded only in 2024. In 2023, atypical extreme heat events (&gt; 40°C) led to elevated flower abortion rates (26%–80%). In contrast, under cooler conditions (&lt; 35°C) in 2024, flower abortion ranged between 25% and 53% (80% ET) and 21%–51% (40% ET). Genotypes were classified on flower abortion and yield to identify high‐yielding genotypes with either high or low flower abortion. Soybean genotypes exhibited distinct flowering plasticity strategies, with some compensating for high abortion through increased flower production, while others maintained yield stability through higher flower retention. LG05‐4317 and PI506862 were identified as promising candidates having differential mechanisms for breeding high‐yielding cultivars with optimised abortion rates. Combined analysis highlighted that phenotypic plasticity in flower number and flower abortion can be exploited to increase soybean yield under diverse environmental conditions.