Influence of Poultry Manure and NPK Fertilization on Growth, Yield and Storability of Onion (Allium cepa L.) Grown Under Rain-fed Conditions

Aim: To evaluate the growth, yield and storability response of two onion varieties to different levels of poultry manure and NPK fertilizer application.
Study Design: The design used was a 2 x 5 factorial arranged in a Randomized Complete Block Design (RCBD) with four replications.
Place and Duration of Study: Field experiments were conducted at the University of Education, Winneba, Mampong-Ashanti campus research fields from October 2009 to February 2010 and March to July 2010.
Methodology: Two onion varieties (Bawku Red and Texas Grano) and five soil amendments (10 t ha-1poultry manure (PM); 15 t ha-1 PM; 20 t ha-1PM; 450 kg/ha NPK fertilizer and no fertilizer) were studied.
Results: The results showed that, on the average, Texas Grano produced higher number of leaves per plant, plant height, total dry biomass, bulb dry biomass, mean bulb weight, bulb diameter and 40-72% greater fresh bulb yield than Bawku Red in both seasons. The soil amendments also had higher number of leaves per plant, 43-83%, 38-90%, 40%, 42-63% and 13-73% greater total dry biomass, dry bulb biomass, mean bulb weight, bulb diameter and fresh bulb yield, respectively, than the control. On the average, the PM treatments produced 7-60% higher fresh bulb yield than the NPK treatment. The Bawku Red variety had lower percentage sprouted and rotten bulbs than Texas Grano, while the control unfertilized check onions stored better than the soil amended treatments. There was no difference between storing onions on the bare concreted floor and in a cane basket.
Conclusion: Growing Bawku Red with application of 10 t ha-1PM or 450 kg ha-1 NPK and Texas Grano with application of 15-20 t ha-1PM are recommended for possible adoption by farmers or further testing on-farm in the transition agro-ecological zone or similar environments.