Impact of Light Quality on Accelerating Soybean Speed Breeding Efficiency Using LED-Based Systems

Abstract Traditional soybean (Glycine max (L.) Merr.) breeding is time-consuming, often requiring 6–12years to develop new cultivars due to lengthy cycles and low efficiency. Speed breeding offers a promising solution to accelerate genetic advancement; however, studies optimising light quality for soybean remain limited. This study evaluated two light-emitting diodes (LEDs) setups, blue (BL) LED light in a growth room and red-white (RW) LED in a speed breeding chamber, on soybean growth, reproductive traits, and yield parameters. Four accessions were tested under 8-hour light (31.6 ± 4.7°C) and 16-hour dark (24.5 ± 2.3°C) cycles. The BL LED light provided an intensity of 231.1 μmol photons m⁻² s⁻¹, while the RW LED delivered a light intensity of 513-μmol photons m⁻² s⁻¹. RW significantly reduced time to flowering (29–33 days) and maturity (66–72 days), compared to BL LEDs (33–38 days) to flowering, (90–95 days) to maturity, and field conditions (~91–103 days). RW LED reduced generation time by 24–31 days compared to field conditions. Moreover, significant differences were observed in plant height, pod number, and seed yield between treatments, while stem thickness and number of trifoliate leaves remained unchanged. Additionally, freshly dried seeds exhibited high germination rates (83.33–100%), confirming seed viability under rapid cycling. This optimised protocol, utilising RW LED light with an 8-hour photoperiod and harvesting at the R6 growth stage (pod-filled), highlights the critical role of light quality in accelerating soybean breeding and provides a refined strategy to enhance breeding efficiency in controlled environments.摘要 传统大豆（Glycine max (L.) Merr.）育种耗时漫长，受限于育种周期长、效率低下，培育新品种通常需要6~12年。快速育种（speed breeding）为加速遗传改良提供了极具潜力的解决方案，但针对大豆光质优化的相关研究仍较为有限。本研究评估了两种发光二极管（Light-emitting diodes, LED）光照配置对大豆生长、生殖性状及产量参数的影响：其一为生长室中的蓝光（BL）LED光照，其二为快速育种箱中的红白光（RW）LED光照。实验设置8小时光照（温度31.6±4.7℃）、16小时黑暗（24.5±2.3℃）的周期，共测试4份种质材料。蓝光LED的光照强度为231.1 μmol photons m⁻² s⁻¹，红白光LED的光照强度为513 μmol photons m⁻² s⁻¹。相较于蓝光LED组（开花期33~38天，成熟期90~95天）与大田条件（成熟期约91~103天），红白光LED组显著缩短了开花时间（29~33天）与成熟期（66~72天）；相较于大田条件，红白光LED将大豆世代时间缩短了24~31天。此外，两组处理间的株高、荚果数与种子产量均存在显著差异，而茎粗与三出复叶数无显著变化。值得注意的是，收获的新鲜干燥种子发芽率可达83.33%~100%，证实了快速循环育种下的种子活力。本优化方案采用红白光LED光照、8小时光周期，并于R6生长阶段（鼓粒期）收获，阐明了光质在加速大豆育种中的关键作用，为可控环境下提升大豆育种效率提供了精细化策略。