Seed longevity as influenced by post harvest processing: delay, fumigation, and drying temperature

Jawad, R. (2026) Seed longevity as influenced by post harvest processing: delay, fumigation, and drying temperature. PhD thesis, University of Reading. doi: 10.48683/1926.00129287

Abstract/Summary

Genebanks are recommended to transfer freshly-harvested seeds to controlled drying environments (cool and dry) promptly after harvest, in order to maintain seed quality and provide good seed longevity in storage; but is this correct? The impact of sequential harvesting and immediate or delayed post-harvest processing (fumigation, threshing, cleaning, drying) on subsequent seed longevity was examined in wheat, its wild relatives, and wild lentil in Lebanon. The effect of (a) initial post-harvest drying temperature on subsequent longevity of durum wheat and wild lentil and (b) fumigation (to control insects) on subsequent seed longevity in wild lentil were also investigated. Delayed processing (seeds kept in cloth bags in the field ex planta for different periods) resulted in equal or often greater seed longevity than immediate processing across all accessions for wheat, its wild wheat, and wild lentil. In durum wheat, subsequent seed longevity increased greatly between 21 and 41 days after heading but declined thereafter. Similarly, longevity increased greatly between 19 and 27 days after 50% flowering in L. nigricans and between 27 and 35 days in L. ervoides. Initial seed drying temperature affected subsequent longevity, but effects varied with harvest date: in durum wheat, 30°C was optimal for the earliest harvests, whereas 15°C was superior at harvest maturity and beyond; in wild lentil species some harvests showed a slight benefit at 15°C (cf. 30°C), while others showed no difference. Fumigation of wild lentil seeds either improved subsequent seed longevity or was no less (or in a few cases only slightly less) than samples not fumigated. The research shows that immature seeds can continue to develop in quality ex planta under the warm, dry conditions of Lebanon, challenging conventional recommendations for immediate post-harvest processing and suggesting a potential role for the delayed processing of seeds in optimizing seed longevity.

Item Type	Thesis (PhD)
URI	https://centaur.reading.ac.uk/id/eprint/129287
Identification Number/DOI	10.48683/1926.00129287
Divisions	Life Sciences > School of Agriculture, Policy and Development
Date on Title Page	September 2025
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