Effects of time of water stress on flowering, seed yield and seed quality of common onion (Allium cepa L.) under the arid tropical conditions of Sudan

► Reproductive stage is the most critical stage for drought stress during crop growth. ► Bolting was the most sensitive stage during the reproductive development of onion. ► Seed yield and quality of onion can be reduced by water stress. ► Frequent irrigation during reproductive stages improves seed yield and quality.