Yield and yield components of coriander under different sowing dates and seed rates in tropical environment

Coriander makes use of favorable environmental conditions when it is sown at optimum time and rate. However, this information is very limited in the southeastern mid-highlands of Ethiopia. Field experiments were, therefore, conducted between 2011 and 2014 at three different research stations to determine optimum sowing dates and rates. The experiment had split plot design in randomized complete block with three replications, in which sowing dates and seed rates were the main and sub-plot treatments, respectively. The four sowing date treatments were June 20, July 10, July 30 and August 20 while the four seeding rate treatments were 30, 40, 50 and 60 kg ha-1. Coriander sowed in the third decade of July at Arsi Robe and from the first to the third decades of July at Kulumsa and Sagure gave the highest fruit and biomass yields. Earlier sowing in the second decade of June, and delayed sowing in the second decade of August brought fruit yield reductions of 37-66 and 37% at Arsi Robe, 27-45 and 58-66% at Kulumsa, and 24-40 and 26% at Sagure, respectively. However, coriander did not respond to seed rates. Owing to the enhanced yields of coriander, intermediate cultivation at a seed rate of 30 kg ha-1 was found optimum