Fennel morphological traits and yield as affected by sowing date and plant density

In order to study the effect of sowing date and plant density on morphological traits and yield of fennel, an experiment was conducted in research field of Islamic Azad University, Birjand branch, Iran in 2009 as a splitplot experiment based on a randomized complete block design with nine treatments and three replications. The main plot was sowing date at three levels of March 19, April 9 and April 30. The sub-plot was plant density at three levels of 6.7, 10 and 20 plants/m2. The results showed that sowing date and plant density significantly affected fennel morphological traits at 1% level. Plant height decreased by 48.2% at third sowing dates as compared with that at the first sowing date. 21-day delay in sowing decreased auxiliary branch number per plant by 59.2% and stem diameter from 5 to 1.8 mm. In addition, the increase in plant density from 6.7 to 20 plants/m 2 decreased auxiliary branch number per plant and stem diameter by 26.4 and 26%, respectively. According the results, single-plant seed and biomass yield and seed yield per hectare were significantly affected by sowing date, plant density and their interaction at 1% level and harvest index was only affected by plant density. As means comparison showed, the delay in sowing from March 19 to April 30 led to 86.7, 86.8 and 85.6 % loss of seed yield per plant, single-plant biomass, seed yield, respectively. Also, the increase in density from 6.7 to 20 plants/m 2 led to the decrease in single-plant biomass and seed yield by 42.5 and 45.8%, respectively. In total, according to the results, it is recommended to use sowing date of March 10 with the density of 20 plants/m2 for the cultivation of fennel in Birjand, Iran.