One experiment was conducted in Suweiri Research farm in Wadi Hadhramout during two seasons (2000/2001 and 2001/2002) to study the effect of sowing dates and spacing on yield and quality of onion using the best variety in the area Bafteem improved–1. The design followed in the experiments was the split – plot with four replications. Sowing dates was carried out in the main plots at 4 and 18 September; 4 and 18 October; and 4 November. While the spacing used in the sub–plots were 20, 30 and 40 cm between bulbs and 70 cm between rows. The results for the two seasons indicated that late sowing date (4 and 18 October and 4 November) gave higher seed yield and long flower holder with no significant differences. The sowing date of November 4th gave significantly higher seed yield in the two season (1.651 and 1.627 t/ha respectively) as compared with the sowing date of September 4th. Sowing spacing of 20 cm between bulbs resulted in significantly higher seed yield (1.870 and 1.854 t/ha during the two season respectively). However, the interaction gave no significant results.

Key Words :Sowing date, Spacing, Yield Quality, Onion, Seiyun