Seed collection and processing practices affect subsequent seed storage longevity in durum wheat and wild relatives

Potential seed storage longevity is influenced by environment during seed development and maturation but postharvest processing may also affect longevity, particularly in accessions with variable maturity or seed shedding. The impact of sequential harvesting and post-harvest processing was examined in durum wheat (Triticum turgidum subsp. durum) and its wild relatives, Triticum turgidum subsp. dicoccoides and T. monococcum subsp. boeoticum. Spikes were collected in sequential harvests as they matured and either processed immediately (fumigated, threshed, cleaned, dried) or delayed (remaining in the field until all plots were harvested). A separate study with durum wheat assessed seed quality throughout development and maturation and the effects of initial post-harvest drying temperatures. Delayed processing resulted in equal or greater seed longevity than immediate processing across all accessions. In durum wheat, longevity improved considerably between 21 and 41 days after heading but declined thereafter. Initial seed drying temperature affected longevity: 30°C was optimal for the earliest harvests, whereas 15°C was superior at harvest maturity and beyond. These findings demonstrate that immature seeds can continue to develop in quality ex planta under warm, dry conditions, challenging conventional recommendations for immediate post-harvest processing and suggesting a potential role for delayed processing in optimising seed longevity.