Fikre Demis’s research while affiliated with Ethiopian Institute of Agricultural Research and other places

Onion is one of the most important vegetable crops in the world including Ethiopia. The field experiment was conducted in Arsi zone at Kulumsa Agriculture Research Center and Ziway Dugda districts under irrigation condition. A total of five improved onion varieties were evaluated in Randomized Complete Block Design with three replications with the objectives of studying the performance and adaptability of improved onion varieties for bulb yield and yield related traits in 2017 during off season. The combined Analysis of variance (variety by location) revealed that significant difference between improved onion varieties for maturity date, marketable and unmarketable bulb yield tons per hectare, bulb length in centimeter, and bulb weight in gram was observed. But non-significant difference for plant height in centimeter, total bulb yield tons per hectare and average bulb diameter in centimeter were observed between improved onion varieties. Except variety Adama Red all the tested improved onion varieties (Melkam, Nafis, Nasik Red and Bombay Red) was well performed and adapted. These varieties were gave more than 40 marketable bulb yield t ha-1. So those improved onion varieties were recommended for the study area and areas of similar agro-ecological zones under off season growing condition.

The experiment was conducted at Kulumsa, South East Ethiopia, using four levels of nitrogen (N) (0, 50,100 and 150 kg N ha À1) and four levels of phosphorus (P) (0, 35, 70 and 105 kg P 2 O 5 ha À1) fertilizers arranged in 4 Â 4 factorial arrangements in randomized complete block design with three replications. The available P was increased after harvest due to the application of N and P fertilizer at the rates of 100 or 150 kg N ha À1 and 70 or 105 kg P 2 O 5 ha À1. More specifically, nutrients concentration and nutrient uptake were significantly (p < .01) varied among treatment combinations and nutrient use efficiency was declined by increasing N and P after optimum rates. The higher physiological efficiency of N (53.47 kg kg À1) and P (580.41 kg kg À1) and the highest apparent recovery of N (19.62%) and P (2.47%) was recorded from application of 50 kg N ha À1 and P at 70 kg P 2 O 5 ha À1 and the highest agronomic efficiency of N (10.78 kg kg À1) and P (15.25 kg kg À1) was recorded from N at the rate of 50 kg N ha À1 and P at 35 kg P 2 O 5 ha À1 , respectively. The combination of N at 100 kg N ha À1 and P at 70kg P 2 O 5 ha À1 was promising combination that generated highest net benefit 488,878.5 ETB (Ethiopian birr) ha À1 with the highest marginal rate of return (36638%) and gave the highest seed yield (1858.82 kg ha À1) with yield increment of about 57.72% over the control. ARTICLE HISTORY