A method for breaking physical dormancy in seeds of the endemic Tibetan plateau shrub Sophora moorcroftiana var. moorcroftiana (Fabaceae) and implications for restoration

Our purpose was to find a practical, easy, and economical method to break physical dormancy (PY) in seeds of Sophora moorcroftiana var. moorcroftiana from the Qinghai-Xizang (Tibet) Plateau of China and thus to facilitate use of this species in restoration. Mechanically-scarified seeds germinated to 100%, but neither dry heat, wet heat, chilling in ice water, nor freezing broke PY. However, 90-100% of the seeds were made water-permeable by subjecting them to wet heat (90 or 100 degrees C)/ice water (0 degrees C) cycles. Water uptake in wet heat/ice water-treated seeds was through the lens in 86% of the seeds that imbibed. Seeds made permeable by wet heat/ice water cycles and then stored dry at 22-24 degrees C for 69 wk germinated to 79%. Thus, seeds can be made water-permeable, stored dry, and then sown later at a restoration site. In trying to germinate seeds of other legumes with PY, wet heat/ice water cycles should be tried when neither wet nor dry heat treatments will make seeds water-permeable.