Irrigation Schedule Affects Onion (Allium cepa L.) Growth, Development, and Yield

ABSTRACT Field experiments were conducted at Bugri and Binduri in northern Ghana in the 1996–97 and 1997–98 onion growing seasons, to determine the optimal irrigation regime for onion: morning and evening daily, morning daily, evening daily, morning and evening alternate days, morning or evening alternate days on bulb yield and yield components of onion cv. Bawku Red. Bulb yield of onion and yield components were significantly (P < 0.05) influenced by irrigation interval. Mean height of onion plants that received irrigation morning and evening, or morning or evening daily were about 39 cm while plants in other treatments were only 34 cm in height. Mean foliage weight when onion was irrigated morning and evening daily was 1.7 kg/plot compared to 1.4 kg/plot when onion was irrigated every other day. The highest bulb yields of 39.8 Mt·ha−1 were obtained when transplants received irrigation morning and evening. Onion bulb yield and yield components generally decreased significantly (P < 0.05) with increase in irrigation regime. Irrigation regime did not have any significant (P < 0.05) effect on the percent total sugar in onion bulb. Over 50% of the farmers in the trial preferred irrigating their onion crop once daily in the morning, thereby confirming the agronomic results obtained in the study.