Variability in seed longevity and viability of two Acacia tortilis subspecies under artificial burial soil storage from three provenances

The aim of this study was to examine the variability in seed longevity and viability of artificially buried seeds of Acacia tortilis subspecies raddiana and subspecies spirocarpa in soil for 18 months among and within three provenances. Burial technique was used to examine seed viability and longevity of two subspecies from three provenances in Sudan. The seeds were collected from three provenances, White Nile, Kassala and River Nile states. 2000 viable sound seeds of both subspecies of the three provenances were buried in soil at 5 cm depth in plastic container in open yard. Artificially buried seeds were followed by 6 months periodic exhumation and germination test during 18 months. The provenance did not show significant differences after 6, 12 and 18 month test time, but the subspecies showed significant differences (P?0.003) at 6 month test. Both Acacia tortilis subspecies had persistent soil seed banks in the three provenances. The seeds can remain viable in the soil for two rainy seasons and reach its maximum germination after 12 month and viability started to decline with increasing burial time in soil. Both subspecies in the three provenances showed above 50% of decayed seeds from total seeds buried in soil during 18 month. The seed viability decreased with increased burial time in soil for the second year and most seeds lost its viability by 18 month burial time. Very little differences was observed between the rate of seed germination, viability and decayed seed between the Acacia tortilis subspecies.