UNVEILING THE IMPACT OF ABIOTIC STRESSES ON ONION YIELD: A COMPREHENSIVE REVIEW

Onion (Allium cepa L.) is a globally significant spice and economic crop, valued for its substantial role in foreign exchange due to high export demand. Onion growth, production, and yield are influenced by different types of abiotic stresses, including salinity, waterlogging, heat, cold, and drought. Insufficient water availability leads to reduced productivity, making a consistent water supply essential for enhancing onion yield. Onions are vulnerable to salt stress particularly, which affects bulb height, the number of bulbs per unit area, and fresh weight, as well as the quality of the harvested bulbs. Waterlogging also significantly impacts bulb development and bulb yield at different growth stages, potentially hindering the movement of nutrients from the source to the sink, thereby decreasing yield. Additionally, the surrounding climate can influence the flavor and taste of onions. Temperature plays a key role in bulbing, with its effects varying among different onion varieties. As temperatures rise, the number of leaves per bulb typically decreases, while bulb weight, bulb diameter, and bulbing index (the ratio of bulb to neck diameter) generally increase. Onions are also affected by salinity, which significantly impacts both bulb yield and quality. This review offers a comprehensive overview of how abiotic stresses affect onion yield.