Nitrogen Fertilizer Rate and Time of Application Affected Yield and Quality of Turmeric (Curcuma longa L.) at Tepi, Southwestern Ethiopia

摘要

Turmeric is one of the most widely grown spice crop in southwestern part of Ethiopia. However, the yield and quality of this crop is low due to many factors. In 2016/2017 main cropping season, an experiment was conducted to determine the effects of nitrogen rate and time of application on yield and quality of turmeric at Tepi. The study consists of five nitrogen rates (0, 46, 69, 92, 115 kg ha~(-1)) and five split applications time (full dose at emergence, half at emergence + half at lag growth stage, 1/3rd at emergence + 1/3rd at lag growth stage + 1/3rd at tillering stage, 1/4th at emergence + 1/4th at lag growth stage + 1/4th at tillering stage + 1/4th at slow growth stage, and 1/5th at emergence + 1/5th at lag growth stage + 1/5th at tillering stage + 1/5th at slow growth stage + 1/5th at maturity stage). A split plot design with three replications was used by assigning nitrogen rate as main plot factor while time of application as sub-plot factor. The result revealed that mother and finger rhizome number, mother and finger rhizome weight, fresh rhizome yield and oleoresin content were significantly affected by the interaction effects of nitrogen rate and time of application. The highest value for the variables measured was recorded at three equal split application of 115 kg N ha~(-1) (1/3rd at emergence + 1/3rd at lag growth stage + 1/3rd at tillering stage). Three times split application of nitrogen produced more yield and better quality as compared to the two times of application in turmeric; the most commonly known time of nitrogen application in many crops. Therefore, turmeric producer in southwestern Ethiopia should apply 115 kg N ha~(-1) nitrogen in three times split application to maximize their turmeric yield and quality.