Effect of Irrigation Frequency on the Productivity of Onion in Plateau State

Onion production in the cool highlands of Plateau State depends on efficient irrigation scheduling to maximise yield while conserving scarce water resources, and empirical data on optimal irrigation frequency are needed to guide smallholder farmers in the region. This study examined the effect of irrigation frequency on the growth and yield of onion (Allium cepa L.) at the Jos Plateau, Plateau State, North Central Nigeria. A randomised complete block design experiment with four irrigation frequencies (daily, every 2 days, every 3 days, and every 5 days) and three replications was conducted during the 2023 dry season. Red Creole onion variety was transplanted at 4 weeks after sowing. Plant height, number of leaves, bulb diameter, bulb weight, and total bulb yield were measured. Irrigation water applied was metered per plot. Results showed that irrigating every 2 days produced the highest bulb yield of 18.4 tonnes per hectare with a water use efficiency of 3.84 kg m-3. Daily irrigation produced comparable yield (18.1 t ha-1) but at significantly higher water consumption and lower water use efficiency. Irrigation every 5 days led to moisture stress symptoms and a 42 percent yield reduction compared to every 2 days. The study concludes that irrigation every 2 days is the most productive and water-efficient schedule for dry season onion production on the Jos Plateau and recommends this frequency be incorporated into Plateau State Agricultural Development Programme irrigation advisory services.

Keywords: irrigation frequency, onion, water use efficiency, Jos Plateau, dry season production