Long-term storage of forage legumes greatly alters the hard seed breakdown pattern in situ

Knowledge of the hard seed content of annual legumes, and its pattern of breakdown, is critical to the understanding of their ecology and management within farming and natural ecosystems. For logistical reasons, seed that has been stored for varying lengths of time is often used for pasture establishment and agronomy experiments. However, the implications of storage on hard seed physiology are unknown. The aim of this study was to explore the impact of seed storage on its subsequent pattern of hard seed breakdown when exposed to field conditions. Experiments examined seed from six different annual legume genotypes that had been either produced the prior year or stored under ambient conditions for 11-22 years. Comparisons were then made between the two seed sources on hard seed breakdown patterns in situ. Although initial hard seed levels were mostly unaffected by storage (seed of five genotypes remained over 93% hard after more than 11 years of storage), the patterns of release from dormancy during exposure to hard seed breakdown conditions of stored seed differed greatly (p < .05) from freshly produced seed. Hard seed in thestoredseed of most genotypes was reduced from >90% to <10% within 68 days over autumn, with shallow burial, whereasfreshseed remained >90% hard during the same period. Given this large and consistent impact, it is recommended that studies of the patterns of hard seed breakdown in legumes compare seed stored under consistent and well-defined conditions.

Automated summary

The storage time of seeds significantly affects the pattern of hard seed breakdown in annual legumes, with stored seeds showing a substantial reduction in hard seed content after exposure, while fresh seeds remain mostly unaffected.