Storage studies were carried out at seed Technology Unit Lab. Mansoura, Dakahlia during  November 2005 till April 2008 on sorghum (Sorghum bicolor L. Mench) seed produced from field experiment which was conducted at the Experimental farm of El-Serw Agriculture Research Station, Dakahlia Governorate in 2005 and 2006 seasons, to study the effect of three irrigation intervals i. e. 14, 21 and 28 days, three potassium fertilizer i. e. 0, 24 and 48 Kg K₂O/fed and four storage periods i. e. 0, 6, 12 and 18 months on germination percentage, seed viability and seedling vigor . The results revealed that prolong irrigation intervals and storage period reduced germinability (as measured by germination percentage, germination after aging, first count, germination index, germination energy and germination rate) and seedling vigor (seedling length, seedling dry weight and its vigor index), meanwhile, increased mean germination time. Increasing potassium fertilizer rates improved seed viability and seedling vigor traits, on the contrast, decreased mean germination time. High significant effect for the interaction between storage period x irrigation intervals, storage periods x potassium fertilizer rates and irrigation intervals x potassium fertilizer rates were obtained for all studied traits. The results suggested that sowing grain sorghum (c.v. Dorado) under limited irrigation conditions and fertilized with 48 Kg K₂O/fed plays a prominent role in increasing seed quality under impact of storage periods.