Late seed maturation improves the preservation of seedling emergence during storage in soybean

Abstract: Long-term survival during dry storage or longevity is a pre-requisite to avoid deterioration, leading to loss of vigor. Longevity is routinely evaluated by the ability to germinate after storage. It increases progressively during seed maturation, after the acquisition of desiccation tolerance. However, the capacity to germinate represents only a part of the success of crop establishment. How seed maturation affects the resistance of several traits, as vigor, associated with seedling establishment, against deterioration was evaluated during seed filling and post-abscission phase of soybean BRS 284 seeds. Three new phenological stages between 7.1 and 7.2 (7.1.1, 7.1.2 and 7.1.3) were introduced to capture the rapid increase in seed longevity. Germination speed started to be affected at 7-14 days after storage depending on the stages. The delay on germination increased with maturation from 7.1.3 to dry mature seeds. The time to 50% loss of elongation capacity of both organs during storage was similar to that of loss of germination. Also, it increased steadily during seed maturation after mass maturity and harvest maturity stages, highlighting the importance of the late phase of seed maturation for building seed vigor.摘要：种子在干燥贮藏过程中的长期存活能力（即种子寿命）是避免种子劣变、防止活力丧失的必要前提。种子寿命通常通过贮藏后的发芽能力进行常规评估。在获得脱水耐性（desiccation tolerance）后，种子寿命会随种子成熟进程逐步提升。然而，发芽能力仅能反映作物建植成功的部分维度。本研究以大豆BRS 284品种的种子为材料，在种子灌浆期及脱落后期，探究了种子成熟过程对与幼苗建植相关的多项性状（包括活力）的抗劣变能力的影响。研究新增了7.1至7.2阶段间的3个新物候期（phenological stages）：7.1.1、7.1.2和7.1.3，以精准捕捉种子寿命的快速提升过程。根据不同物候期，贮藏后的7~14天内，发芽速度开始受到影响。从7.1.3阶段至干燥成熟种子，发芽延迟程度随种子成熟度逐步加剧。贮藏期间，两种器官的伸长能力丧失50%所需的时间与发芽率丧失50%所需的时间相近。此外，该指标在生理成熟期（mass maturity）和收获成熟期（harvest maturity）后的种子成熟阶段持续升高，凸显了种子成熟后期对构建种子活力（seed vigor）的重要性。